Scielo RSS <![CDATA[Revista de Ciências Agrárias]]> http://www.scielo.mec.pt/rss.php?pid=0871-018X20100001&lang=en vol. 33 num. 1 lang. en <![CDATA[SciELO Logo]]> http://www.scielo.mec.pt/img/en/fbpelogp.gif http://www.scielo.mec.pt http://www.scielo.mec.pt/scielo.php?script=sci_arttext&pid=S0871-018X2010000100001&lng=en&nrm=iso&tlng=en <![CDATA[<b>Heavy metals in wild mushrooms from contaminated areas</b>]]> http://www.scielo.mec.pt/scielo.php?script=sci_arttext&pid=S0871-018X2010000100002&lng=en&nrm=iso&tlng=en Los hongos, saprobios y micorrícicos, desempeñan un papel importante en los eco­sistemas forestales, en especial en los ciclos biogeoquímicos. Los saprobios actúan en los procesos de degradación y mineraliza­ción de la materia orgánica, mientras que los micorrícicos son esenciales en la adquisi­ción y translocación de los nutrientes a las plantas huéspedes. En lugares contaminados por metales pesados la simbiosis micorrícica confiere resistencia a la plantas; en algunos casos se ha demostrado que plantas infecta­das pueden sobrevivir más fácilmente a la contaminación que las no micorrizadas. El micelio secuestra la fracción asimilable de los metales pesados disminuyendo la trans­locación a las plantas. Los cuerpos fructífe­ros de los hongos son consumidos por una gran cantidad de animales y también por el hombre. Algunas setas silvestres tienen un alto valor nutricional y son un recurso natu­ral con un valor económico importante. Sin embargo, la acumulación de metales pesa­dos por los hongos puede representar un riesgo para la salud tanto para humanos como para otros seres vivos. Suelos, hongos y hojarasca fueron mues­treados en una zona contaminada con meta­les pesados en las proximidades de una mina de Pb-Zn (Cd), actualmente abando­nada (Loma Charra, Soria). Los contenidos de metales en suelos, hojarascas y hongos indican un elevado grado de contaminación en relación a áreas cercanas, utilizadas como control, no afectadas por actividad minera. En el suelo los contenidos de Zn: 797-3540 mg/kg, Cd: 2,1-10 mg/kg y Pb: 1485-8166 mg/kg, en hojarasca (Zn: 92­1475 mg/kg; Cd 0,9-4,2 mg/kg; Pb: 54­2756 mg/kg) y en setas (Zn 118-915 mg/kg; Cd: 1,2-45,2 mg/kg y Pb 12-1475 mg/kg). Los factores de bioacumulación indican alto riesgo medioambiental.<hr/>Saprotroph and mycorrhizal fungi play an important role in forest ecosystem, particu­lary in the biogeochemical cycles. Sapro­ troph fungi are crucial for degradation of the organic matter. Mycorrhizal improve their hosts mineral nutrition. The mycorrhizal as­sociations give resistance in contaminated areas to the plants. Sometimes inoculated plants hold up better the contamination that non-inoculated plants. The mycelia absorbs (extracts) the soil available fraction and de­crease the heavy metal concentration in the plants. The fruit-bodies can be eaten by many animal specie as well as by humans. Some specie wild fungi have a high nutri­tional value and represent an important eco­nomical resource. Soil, mushrooms and litter were sampled in a lead (Pb)-zinc (Zn) mine (Soria prov­ince, Spain). The distribution of metals in soil, litter and fungi shows a high concentra­tion of metals in relation to the control ar­eas. The Zn soil contents ranges are 797­3540 mg/kg, Cd: 2.1-10 mg/kg and Pb: 1485-8166 mg/kg, Litter content ranges: (Zn: 92-1475 mg/kg; Cd 0.9-4.2 mg/kg; Pb: 54-2756 mg/kg) and fruit-bodies ranges: (Zn 118-915 mg/kg; Cd: 1.2-45.2 mg/kg and Pb 12-1475 mg/kg). The bioacumula­tion factors show high environmental and toxicological risks. <![CDATA[<b>Using LEACHM model for evaluation and optimization of the use low quality water in citrus</b>]]> http://www.scielo.mec.pt/scielo.php?script=sci_arttext&pid=S0871-018X2010000100003&lng=en&nrm=iso&tlng=en Para evaluar el riesgo de salinizacion en suelos con cultivo de cítricos se utilizó el modelo LEACHM que fue calibrado y vali­dado en 7 perfiles de la cuenca sedimentaria de Torreblanca (Castellón, España). Se apli­có un análisis de escenarios mediante la combinación de: cultivos, clima, suelos, tipo de riego y calidad de las aguas y se analiza­ron estrategias alternativas mediante la utili­zación de mezclas de aguas. Los índices estadísticos mostraron un buen ajuste del modelo en la zona radicular entre 200-600 mm y una sobreestimación de la humedad en los horizontes inferiores. En cuanto al riesgo de salinización los resulta­dos confirmaron el uso inapropiado de las aguas con CE>3 dS/m. Se recomienda el uso de aguas con 2-3 dS/m únicamente en el riego por goteo y se propone una alternativa que disminuya el riesgo de salinización mediante la aplicación de diferentes tipos de agua en función de la estación.<hr/>To evaluate the risk of salinization in soils with citrus crop we use the model LEACHM calibrated and validated in 7 pro­files of the Torreblanca's sedimentary basin (Castellón, Spain). An analysis of scenes was applied by means of the combination of: crop, climate, soils, type of irrigation and waters quality and analyzed alternative strategies by means of the utilization of wa­ter mixtures. The statistical index indicates a better ad­justment of the model in the rootzone be­tween the 200-600 mm and a light up-estimation of the moisture content in the lower layers. As for the risk of salinization the results confirm the inappropriate use of the waters with CE > 3 dS/m. The water use with 2-3 dS/m is recommended only in the drip irrigation and there proposes an alterna­tive that diminishes the risk of salinization by means of the application of different types of water depending on the season. <![CDATA[<b>Comparison of amendments applied to an arsenic contaminated soil from a mining area and their effect on plant growth</b>]]> http://www.scielo.mec.pt/scielo.php?script=sci_arttext&pid=S0871-018X2010000100004&lng=en&nrm=iso&tlng=en Estudou-se o efeito de correctivos (óxido de ferro, Fe; matéria orgânica, MO; fosfato de cálcio, PCa), aplicados a um solo da área mineira de Penedono contaminado com As, no crescimento de tomateiro e salsa. Usa­ram-se, como controlos, este solo sem cor­rectivos e um solo não contaminado. Duran­te o crescimento mediu-se a altura das plan­tas, comprimento foliar e teor relativo de clorofila. Na colheita final determinaram-se os pesos frescos e secos. Os correctivos influenciaram a disponibi­lidade de As no solo, relativamente ao ori­ginal: Fe manteve-a enquanto MO e PCa a aumentaram. Ambas as espécies foram afec­tadas pelo arsénio, porém a resposta aos tra­tamentos foi diferente. A altura, compri­mento dos folíolos, teor de clorofila, peso seco e número de frutos dos tomateiros foi significativamente superior em MO do que em Fe e controlo. O correctivo MO apresen­tou resultados promissores relativamente ao crescimento e produtividade do tomateiro. Contudo, o PCa (12 g kg-1) foi o melhor cor­rectivo para o crescimento da salsa.<hr/>Three amendments (iron oxides, Fe; or­ganic matter, MO; calcium phosphate, PCa) were applied to a naturally contaminated soil with arsenic and their effect on the growth of tomato plants and Italian parsley was studied. The results indicate differences associated with the availability of arsenic in the soil in the presence of amendments: Fe had no influence on arsenic availability compared with the unamended soil, while MO and PCa increased the availability of arsenic. Though both plant species have been affected by arsenic toxicity, the re­sponse to treatments relatively to plant growth was different. Tomato plants pre­sented greater growth in terms of height, leaf length, relative chlorophyll content, dry weight and fruit production when MO was used as amendment. By the contrary, the Italian parsley presented the best growth when PCa (12 g kg-1) was added to the con­taminated soil. <![CDATA[<b>Effect of controlling competing vegetation and fertilization on maritime pine (<i>Pinus pinaster</i> Ait.) growth and nutrient concentration</b>]]> http://www.scielo.mec.pt/scielo.php?script=sci_arttext&pid=S0871-018X2010000100005&lng=en&nrm=iso&tlng=en Para determinar o interesse do controle da vegetação do sob coberto e da aplicação de N, P e K no crescimento e concentração de nutrientes em pinheiro bravo (Pinus pinas­ter Ait.) escolheu-se um pinhal com seis anos onde, em Julho de 2002, foram aplica­dos cinco tratamentos: testemunha (T); corte e remoção da vegetação (CR); corte, remo­ção da vegetação e fertilização (CRF); corte e destroçamento da vegetação (CD); corte, destroçamento da vegetação e fertilização (CDF). Entre 2002 e 2007, e em relação a todos os parâmetros dendrométricos considerados, altura, diâmetro, área basal e volume, verifi­cou-se que os acréscimos ocorridos no tra­tamento CDF foram superiores (p<0,05) aos dos outros tratamentos. Os menores cresci­mentos ocorreram na Testemunha e/ou no tratamento CR. Em geral, não houve dife­renças significativas entre os tratamentos CD e CRF. Os resultados indicam, assim, que a remoção da vegetação do sob coberto deverá ser considerada apenas se forem adi­cionados fertilizantes (tratamento CRF) a fim de se evitarem efeitos negativos no crescimento. A concentração de N, P e K nas agulhas só aumentou em 2003 e 2004 com a aplicação dos adubos, embora de forma não significativa.<hr/>To study the interest of controlling the understory vegetation and the addition of N, P and K on the growth and nutrient concen­tration in maritime pine (Pinus pinaster Ait.), a field trial was established in a 6-year old pine forest. Five treatments were tested: control (T); cutting and removal of compet­ing vegetation (CR); cutting, removal of competing vegetation and fertilization (CRF); cutting and chipping of competing vegetation (CD); cutting, chipping of com­peting vegetation and fertilization (CDF). Between 2002 and 2007, growth in the CDF treatment was higher (p <0.05) than in the other treatments. The lowest growth oc­curred in control and/or in the CR treatment. In general, there were no differences between CD and CRF treatments. Therefore, these re­sults point out that removal of competing vegetation should be considered only if fertil­izers are added (CRF treatment) in order to avoid negative effects on pine growth. Ap­plying fertilizers increased N, P and K con­centrations only in 2002 and 2003, although the increase was not significant. <![CDATA[<b>Model of irrigation management on green spaces</b>]]> http://www.scielo.mec.pt/scielo.php?script=sci_arttext&pid=S0871-018X2010000100006&lng=en&nrm=iso&tlng=en Este Modelo de Gestão de rega foi con­cebido para aplicação aos Espaços Verdes de Lazer. O Modelo reconhece a água como um factor de produção e optimiza a sua aplica­ção na rega de Espaços Verdes, dando espe­cial atenção e cuidado à variação temporal e espacial dos factores intervenientes. O Modelo envolve diversas matérias: as espécies vegetais implantadas ou a plantar, fases fenológicas, os solos existentes, sua localização e características físicas, a topo­grafia, os elementos e factores do clima. Os métodos a utilizar são os preconizados em Allen et al. (1998): o método da FAO Penman-Monteith para o cálculo da evapo­transpiração de referência, a técnica dos coeficientes culturais duais para a obtenção da evapotranspiração cultural, e a oportuni­dade de rega pelos balanços hídricos. O Modelo integra a programação de algo­ritmos implementados em Visual Basic 6, VB6 e um Sistema de Informação Geográ­fica (SIG). O Modelo determina os parâme­tros de rega em tempo real, momento da rega, dotação, tempo de rega, intervalo de tempo entre regas, bem como, para a asper­são, a intensidade média de precipitação e grau de pulverização. A utilização do Modelo é feita associada à estação meteorológica automática e ao sis­tema de rega também automático.<hr/>The presented Model of Irrigation Man­agement was designed for application on green spaces and leisure areas. The Model recognizes water as a produc­tion key-factor and optimizes its use on the irrigation of green spaces, giving particular attention to the temporal and spatial varia­tion of input variables. Variables entered in the Model included existing or future target plant species, phenological phases, type of soil (i.e. loca­tion and physical characteristics), topogra­phy and climate factors. Model construction was similar to the methods outlined in FAO Report 56, namely: the method of Penman-Monteith for the calculation of reference evapotran­spiration, the use of dual cultural coeffi­cients to obtain cultural evapotranspiration and the opportunity of irrigation according to the hydric balance. The Model integrates the programming of algorithms implemented in Visual Basic 6, VB6 and a Geographic Information System (GIS). The Model provides the irrigation pa­rameters in real-time scale, the timings for irrigation, depth per irrigation, the period of irrigation, time between two irrigation epi­sodes, and for the sprinkle irrigation, the mean application rate and the degree of pul­verization. The Model is used in association with an automatic weather station and irrigation sys­tem. <![CDATA[<b>Soil, phosphorus and organic matter loss by water erosion in revege­tated plots with autoctonous shrubs under semi-arid climate</b>]]> http://www.scielo.mec.pt/scielo.php?script=sci_arttext&pid=S0871-018X2010000100007&lng=en&nrm=iso&tlng=en Se ensayan arbustos (Atriplex halimus (Ah)y Thymus zygis (Tz)) en laderas del centro peninsular. Se estudia la erosión y la contaminación difusa, analizando el contenido de materia orgánica (MO)y fósforo (P2O5) en suelo y sedimentos. En comparación con el control, Ah presentó un descenso significativo de escorrentía de un 47% y un 24% menos de erosión, pero Tz presentó un 12% más de escorren­tía y un 152% más de pérdida de suelo. Se evidencian cocientes de enriquecimiento de MO y P2O5 en sedimentos erosionados y relaciones entre la erosión y el conteni­do en MO y P, observándose ecuaciones de regresión con coeficientes de correla­ción elevados, R=0,91 y 0,87 respectiva­mente.<hr/>Two treatments with shrubs (Atriplex halimus (Ah) and Thymus Zygis (Tz)) were tested on hillsides from central Spain. It was studied the erosion and dif­fuse contamination by analyzing organic matter content (OM) and phosphorus (P2O5) in soil and sediments. Compared with the control treatment, Ah presented a significant decrease of runoff and erosion, 47% and 24% lower respectively, but Tz showed 12% more runoff and 152% more erosion than control. Enrichment ratios of OM and P2O5 are evident in eroded sedi­ment and also a strong relation between erosion and OM and P2O5 content was found, showing regression equations with high correlation coefficients, R=0.87 and 0.91 respectively. <![CDATA[<b>Effects of irrigation with injection of air in soil moisture, nitrate avail­ability, electrical conductivity and lettuce productivity grown in plastic greenhouse</b>]]> http://www.scielo.mec.pt/scielo.php?script=sci_arttext&pid=S0871-018X2010000100008&lng=en&nrm=iso&tlng=en Este trabalho teve como objectivo veri­ficar se a injecção de ar junto a água de rega gota-a-gota enterrada, afecta a humi­dade do solo, a disponibilidade de azoto nítrico, a condutividade eléctrica e o cres­cimento e produtividade da alface. Para tal realizou-se um ensaio com a alface variedade “Mention” cultivada em estufa plástica e localizada na Herdade Experi­mental da Mitra-ICAAM, da Universida­de de Évora -Portugal. Utilizou-se o deli­neamento experimental blocos ao acaso com quatro repetições, com os tratamen­tos: rega com injecção de ar (CAR), e rega sem injecção de ar (SAR). O ar foi introdu­zido na água de rega por meio de um injector “Mazzei”. O teor de humidade na camada superficial (0-0,05 m) foi seme­lhante para os dois tratamentos, alcançan­do valores em torno de zero. Em termos de concentração de azoto nítrico (NO 3-) os valores observados na camada 0,10­0,20 m, aos 35 e 47 dias após a transplan­tação, foram mais elevados no tratamento CAR. Aos 47 dias após a transplantação, os níveis médios de NO3-foram de 95,33 e 67,94 ppm nos tratamentos CAR e SAR, respectivamente. A densidade radical no tratamento CAR na camada de 0-0,10 m do solo foi 34 % superior em relação ao SAR. A produção comercial não foi afectada pelo tratamento. A falta de resposta da cultura ao acréscimo de azoto nítrico e da densidade radical pode estar relacionada com o curto ciclo da cultura e/ou com o elevado teor de azoto presente no solo, ou ainda com a profundidade que os goteja­dores foram instalados e não com a fun­cionalidade do injector de ar.<hr/>The objective of the present study was to evaluate the effect of the air injection through subsurface drip irrigation (oxyga­tion) in soil moisture, availability of nitro­gen oxide, and electrical conductivity, plant growth and yield of lettuce, variety "Men­tion", cultivated in plastic greenhouse. The experiment was carried out at the Mitra-ICAM, an Experimental Station of the Uni­versity of Évora -Portugal. The experiment was arranged in a randomized block design with four replications and the treatments were: irrigation with (CAR) and without (SAR) air injection. The air was introduced into irrigation water through a jet "Mazzei". The soil moisture in the surface layer (0­0.05 m) was similar for the two treatments, reaching values around zero. Concerning NO3-concentration in 0.10-0.20 m soil layer at 35 and 47 days after planting was higher in the treatment CAR. At 47 days after plant­ing, the average levels of NO3-were 95.33 and 67.94 ppm respectively in treatments CAR and SAR. Air injection increased root length density at 0-0.10m depth. The com­mercial yield was not affected by air injec­tion. The lack of response by the crop to the increase of the soil nitrate concentration and root length density could be related with the short cycle of the crop and/or with high con­tents of nitrogen present in the soil, or result of the dripline setting depth. <![CDATA[<b>Effects of soil application of olive mill waste water, solid olive mill waste and a compost on total and mineral nitrogen and on organic carbon</b>]]> http://www.scielo.mec.pt/scielo.php?script=sci_arttext&pid=S0871-018X2010000100009&lng=en&nrm=iso&tlng=en A aplicação ao solo, dos resíduos dos lagares de azeite, em bruto ou após um pro­cesso de compostagem, poderá assegurar um destino final para estes resíduos e ao mesmo tempo permitir a valorização agríco­la de alguns dos seus componentes. Neste estudo, avaliaram-se os efeitos da aplicação ao solo de uma água-ruça (AR) e de um bagaço (B) provenientes de um lagar com sistema de extracção de três fases, bem como de um composto (C) sobre os teores de azoto total e mineral, de carbono orgâni­co e sobre a relação C/N no solo. Estabeleceram-se dois ensaios em vasos utilizando Hordeum vulgare var. Sereia como cultura teste e dois solos distintos: um Cambissolo calcárico -CMca e um Cambissolo dístrico -CMdy. Os ensaios foram delineados em blocos completos casualizados com três repetições, considerando dez tratamentos experimentais: uma testemunha e três níveis de aplicação de cada um dos três produtos mencionados, equivalentes a 80, 160 e 240 m³/ha. Os resultados obtidos revelaram que a aplicação de B e de C ao solo provocou um aumento significativo (p≤0,05) nos teores de carbono orgânico, de azoto total e também na razão C/N de ambos os solos. A aplicação de AR e de B provocou um decréscimo significativo (p≤0,05) inicial, nos teores de azoto nítrico, no CMca. Tal efeito não se verificou com a aplicação do composto, o que sugere que, a técnica da compostagem poderá ser benéfica relativamente àqueles subprodutos.<hr/>Olive mill wastes application to agricultural soils, directly or after composting, could represent a valuable option for their disposal and a good strategy for their valorization. The aim of the experiment was to evaluate the effects of soil application of olive mill wastewater (OMW) and solid olive mill waste (SOMW) from a three phases olive mill, as well of a compost (C) obtained from a mixture of these byproducts with organic matter residues from gardens and croplands, on soil total and mineral nitrogen, on organic carbon and on carbon/nitrogen ratio. Two factorial pot experiments were established using Hordeum vulgare var. Sereia as test crop and two soils - a Calcaric cambisol (CMca) and a Dystric cambisol (CMdy). The experiment was arranged into completely randomized blocks, with three replications, performing ten treatments. Four levels - 0, 80, 160 and 240 m³/ha - of each product were applied. The obtained results showed a significative increase (p≤0,05) on organic carbon, total nitrogen and C/N ratio, in both soils by SOMW and C application. An initial significative decrease (p≤0,05) on NO3-N was verified with the application of OMW and SOMW on the CMca soil. Results showed that composting avoid initial nitrogen immobilization can be a better alternative to those by-products. <![CDATA[<b>Influence of soil grinding degree on the determination of total nitrogen, total carbon and organic carbon concentrations.</b>]]> http://www.scielo.mec.pt/scielo.php?script=sci_arttext&pid=S0871-018X2010000100010&lng=en&nrm=iso&tlng=en A Norma ISO 11464, relativa à prepara­ção de amostras de terra para análise físico­química, preconiza, para tomas de material inferiores a 2 g, que as mesmas sejam sujei­tas a moenda fina (< 0,250 mm) de modo a permitir que a homogeneidade da amostra seja tal que a variabilidade dos resultados seja minimizada. A fim de avaliar a possibi­lidade de dispensar este moroso passo na determinação dos teores de azoto total e carbono total e orgânico, procedeu-se à quantificação destes elementos em sub­amostras apenas moídas manualmente e cri­vadas (< 2 mm) e noutras que, posterior­mente à crivagem, foram sujeitas a uma moenda fina. Utilizaram-se, para o efeito, amostras de sete solos de Portugal Conti­nental, derivadas de diferentes materiais: (a) arenitos (Podzol - PZ); (b) complexo deri­vado de xistos e “rañas” (Luvissolo férrico - LVfr); (c) dioritos ou gabros (Vertissolo pélico - VRpe); (d) granitos (Cambissolo dístrico -CMdy); (e) calcários (Cambissolo calcárico - CMca); (f) aluviões (Fluvissolo - FL) e (g) xistos (Luvissolo háplico - LVha). A determinação do carbono total foi efec­tuada pelo método da combustão seca num analisador elementar segundo a Norma ISO 10694, o teor de carbono orgânico foi calcu­lado a partir do carbono total deduzindo a quantidade deste elemento que está presente na forma de carbonatos e a determinação do azoto total foi efectuada por combustão seca da amostra num analisador elementar segundo a Norma ISO 13878. Os resultados obtidos revelaram que o grau de moenda não afectou significativa­mente (p>0,05) os resultados e a moenda fina da amostra não aumentou significati­vamente (p>0,05) a precisão dos mesmos, quer em termos do teor de azoto total quer de carbono total e orgânico, sugerindo ser dispensável a moenda fina das amostras.<hr/>According to ISO Standard 11464 (Soil quality -Pretreatment of samples for physico­chemical analyses) for test samples below 2 g, the air dried soil sample must be ground to a particle diameter ≤ 0.25 mm, in order to have a homogeneous test sample and, there­fore, minimize the variability of results. This is quite a time consuming task. The aim of this study was to compare the influence of two different degrees of grinding (<2mm and < 0.15 mm) on the determination of total ni­trogen, total carbon and organic carbon, with test samples of 0,5 g. These elements were analyzed in 7 different soils from Continental Portugal, derived from different parent mate­rial. Five representative samples were taken from each soil and manually crushed to pass a 2 mm plastic sieve. Each sample was then split in two portions: in one of them, nitrogen and carbon were analyzed directly on the fine earth fraction (< 2 mm); on the other portion, the analyses were carried out only after grind­ing the soil sample on a agate mill till it just passed a plastic sieve of < 0.15 mm. Total ni­trogen and carbon were determined by dry combustion on a CNS elemental analyzer, according to ISO Standards 13878 and 10694, respectively. Organic carbon was de­termined indirectly after correction of the to­tal carbon content for the carbonates present in the soil sample. Results suggest that the soil grinding degree had no significant (p>0.05) effect on C and N concentrations. Grinding the soil to 0.15 mm didn’t increase significantly (p>0.05) the precision of results suggesting that, for the determination of total nitrogen or total and organic carbon, it is not necessary to grind the soil to a fraction less than 2 mm. <![CDATA[<b>Characterization of pedological parameters that influence almond productivity</b>]]> http://www.scielo.mec.pt/scielo.php?script=sci_arttext&pid=S0871-018X2010000100011&lng=en&nrm=iso&tlng=en Several almond orchards have been studied in south-eastern Spain to characterize and evaluate the soils dedicated to the cultivation of different cultivars in order to identify the parameters that most affect yield. The percentage of gravels, high in several of the soils studied, correlated negatively with the clay content and Water Holding Capacity (WHC) as did the percentage of CaCO3 with available potassium. The greatest yield corresponded to soils with higher surface porosity and lower subsurface porosity, enaulic or gefuric related distribution in the surface horizons and porphyric related distribution in the subsurface horizons. Both for the Fertility Capability Classification as well as for the Agricultural Productivity Evaluation (FAO), the soils with the best characteristics for the crop did not coincide with those in which the greatest yield was found (Ferragnès registering the highest yield), due to the flowering period of the rest of the cultivars selected, which was more influenced by the climatic characteristics of the zone, especially temperature.<hr/>Estudaram-se vários pomares de amendoeira situados no Sudeste de Espanha com o objectivo de caracterizar e avaliar os solos dedicados à cultura de diferentes cultivares de forma a identificar os parâmetros que mais afectam a produtividade. A percentagem de cascalho, presente em quantidades elevadas, em alguns dos solos estudados, está negativamente correlacionada com o teor de argila e a capacidade máxima de retenção de água, bem como a percentagem de CaCO3 com o teor de potássio disponível no solo. As maiores produções corresponderam aos solos que apresentaram uma maior porosidade superficial e uma menor porosidade sub superficial, com uma distribuição enáulica ou gefúrica nos horizontes superficiais e uma distribuição porfírica nos horizontes sub superficiais. Os solos que melhores características apresentam para este tipo de cultura, quer no que se refere à sua fertilidade (Fertility Capability Classification), quer em termos da sua aptidão agrícola (FAO), não foram os que permitiram obter as maiores produções (tendo-se registado a maior produção para a cultivar Ferragnès), uma vez que o período de floração das restantes cultivares seleccionadas foi mais influenciado pelas condições climáticas da zona, nomeadamente pela temperatura, do que pelas características do solo. <![CDATA[<b>Soil solution in soils under <i>Erica andevalensis </i>formations in the Riotinto mining area (Huelva, SW Spain)</b>]]> http://www.scielo.mec.pt/scielo.php?script=sci_arttext&pid=S0871-018X2010000100012&lng=en&nrm=iso&tlng=en Erica andevalensis es un brezo endémi­co de la Faja Pirítica Ibérica, catalogado en peligro de extinción por la Junta de Andalucía (Decreto 104/1994, Ley 8/2003), que crece espontáneamente en áreas mineras. El estudio de la disolución de los suelos puede ser una herramienta útil para caracterizar las condiciones geo­químicas de su hábitat. Hemos analizado la disolución del suelo en 11 parcelas de dos áreas mineras de Riotinto. La espe­ciación de iones solubles se estimó me­diante el programa SOLMIN88. Los resultados indican que crece adecua­damente en un amplio rango de condicio­nes, tolerando bien fuerzas iónicas de hasta 10-2 M, disoluciones de reacción hiperácida (3,43) a neutra (6.97) y con concentraciones variables de iones (sulfato 4-376, Ca 0,3-25 y Mg 0,1-25 mg L-1) y metales (Al 0,1-10, Cu 0,01-3,94, Pb 0,01-0,23, Zn 0,01-1,88 y Mn 0,02-2,81 mg L-1). E. andevalensis parece indiferente al catión que domina la disolución del suelo, confirmándose su carácter Al-tolerante.<hr/>Erica andevalensis is an endemic heather in the Iberian Pyrite Belt listed as endan­gered species by Junta de Andalucía (De­cree 104/1994, Law 8/2003) which grows spontaneously in mining areas. The study of soil solution may be a useful tool to charac­terize the geochemical conditions of its habitat. We analyzed the soil solution of 11 plots from two mining areas in Riotinto. Ion speciation was obtained using the SOL­MIN88 software. Our results indicate that it grows ade­quately under a wide range of conditions, being tolerant to ionic strength until up to 10-2 M, soil solutions ranging from hyper­acid (3.43) to neutral (6.97) and with vari­able ions (sulphate 4-376, Ca 0.3-25 and Mg 0.1-25 mg L-1) and metals (Al 0.1-10, Cu 0.01-3.94, Pb 0.01-0.23, Zn 0.01-1.88 y Mn 0.02-2.81 mg L-1) concentrations. This spe­cies seems to be indifferent to the dominant cation of the soil solution. The Al-tolerant character of this species was also confirmed. <![CDATA[<b>Study of the application of SMC as fertilizer and as organic amendment on a vineyard soil</b>]]> http://www.scielo.mec.pt/scielo.php?script=sci_arttext&pid=S0871-018X2010000100013&lng=en&nrm=iso&tlng=en La Rioja genera anualmente 306.000 Tm de Sustrato Postcultivo de Hongos (SPCH), los cuales se depositaban en ver­tederos que constituyen una fuente de contaminación de aguas subterráneas. En la agricultura actual, los SPCH son am­pliamente utilizados para reponer pérdidas de materia orgánica, aumentar la disponi­bilidad de fósforo y potasio, mejorar la capacidad de retención de agua y la poro­sidad del suelo. En este trabajo se evalúa la aplicación anual de SPCH como enmienda orgánica y/o fertilizante en un ensayo con tres blo­ques y cinco tratamientos sobre Haploxe­repts típico, en una parcela vitícola. Se estu­dian dos tipos de SPCH: “Fresco” (sin tra­tamiento tras su utilización) y “Recompos­tado”; y tres cantidades netas: Testigo, 8.000 y 25.000 kg·ha-1 (m.s.). Se determinó la distribución en el perfil del suelo de la materia orgánica, N (N-org+N-NH 4+), pH, conductividad eléctrica, P, K+, Ca2+, Mg2+ , Na+, SO4(2-), Fe, Mn, Cu, Zn, y B, entre otros elementos. Tras dos aplicaciones no se ha observado un aumento del contenido de la mayoría delos nutrientes. Únicamente los tratamientos con mayor dosis de aplicación han incre­mentado el contenido K+ y sulfatos extraí­bles en el horizonte superficial (0-30 cm) así como los valores de C.E, aunque éstos no han alcanzado niveles que supongan un riesgo para el cultivo. Sin embargo, y dado las cantidades aportadas, se debe realizar un seguimiento de la CE y del contenido en nu­trientes del suelo para calibrar el potencial fertilizante del SPCH, velocidad de libera­ción y las pérdidas que podrían generar. El SPCH podría estar actuando como un ferti­lizante de liberación lenta, por lo que aplica­ciones sucesivas podrían conducir a un aporte excesivo de nitrógeno y otros nu­trientes que afectarían a la producción y/o la calidad del mosto, además de agravar el problema de lixiviados en zonas vulnera­bles.<hr/>At present, 306.000 Tm of Spent Mush­room Substrate (SMC) are yearly produced at La Rioja. These SMC have been accumu­lated at opencast dumping sites, which are a serious contamination source. Nowadays, in the agriculture, different SMC are widely used to replace the soil organic matter losses, to enhance the exchangeable phos­phorus and potassium, and to improve the soil porosity and its water retention. In this work, the annual application of SMC is evaluated as fertilizer and as or­ganic amendment for vineyard soil. A ex­perimental assay is performed with three blocks and five treatments on a Typic Hap­loxerepts. Two SMC: Recomposted SMC, and “Fresh” SMC (No recomposted SMC) were evaluated for three SMC total amounts: 0, 8.000 and 25.000 kg·ha-1 (d.m.). The Organic matter, N (N-org+N-NH4+), pH, electrical conductivity, extractable P, K+, Ca2+, Mg2+, Na+, SO4(2-), Fe, Mn, Cu, Zn, and B, among other elements, were evalu­ated in the soil profile. Nutrient content was not increased after two annual SMC applications on the soil for the most of nutrients. Only the higher amounts of SMC increased the available K+ and extractable sulphate in the upper hori­zon (0-30 cm). CE was also increased, al­though its values don’t represent a risk for the crop. However, considering the SMC amounts applied, it is neccessary the moni­toring of the CE and nutrient content in the soil to evaluate the SMC potential as a fertil­izer; velocity of the nutrient liberation; and the possible loss of nutrients. The SMC be­haviour could be simmilar to the behaviour of a low-liberation fertilizer. Therefore, con­tinuous applications could produce an ex­cessive amount of nitrogen and other nutri­ents in the soil, which will affect the crop yield and must quality. In addition, an ex­cessive liberation could agravate the nutrient lixiviation in vulnerable areas. <![CDATA[<b>Quantitative parameters for assessing susceptibility to erosion in tropical Dominican soils</b>]]> http://www.scielo.mec.pt/scielo.php?script=sci_arttext&pid=S0871-018X2010000100014&lng=en&nrm=iso&tlng=en La capa superficial de los suelos de dife­rentes tipos de bosques tropicales húmedos y secos presentes en la provincia de Peder­nales (República Dominicana), ha sido eva­luada mediante diferentes parámetros rela­cionados con el proceso de erosión: tamaño de partículas, cociente limo/arcilla y un es­timador de la posibilidad de pérdida de sue-lo. Algunos de los ecosistemas más valiosos están amenazados por talas y quemas y por la implantación de cafetales, de ahí el interés y objetivo de este trabajo, para ver como es­tos usos y manejos afectan a los suelos. Los resultados se presentan comparando los pa­rámetros estudiados en 79 muestras analiza­das según las unidades paisajísticas (bos­ques con y sin usos agropascícolas), así co­mo según las litologías predominantes en las mismas: calizas cristalinas, calizas car­bonatadas sobre alteritas y calizas coralinas. El trabajo muestra por vez primera para esta región, parámetros cuantitativos respecto a procesos edáficos vinculados a la erosión en dicho territorio. Otro dato relativamente no­vedoso es el utilizar la metodología láser para los análisis del tamaño de partículas.<hr/>The topsoil layers (0-20 cm) of different types of wet and dry tropical forests of the Pedernales province (Dominican Republic), both natural and cultivated, were assessed in terms of different parameters related to the erosion processes: particle size, silt/clay ra­tio, and an estimate of the possible soil loss. Some of the soils of the most valuable eco­systems are threatened by the introduction of coffee and hence the interest and objec­tive of this work. We present these data for 79 soil samples according to the corresponding landscape units (forests) along with their dominant lithologies (crystalline limestones, carbon­ated limestones on alterites and coral lime­stones). The novelty of this study is that it uses quantitative variables to describe ed­aphic processes linked to erosion in this re­gion, that had never been quantitatively studied the soils. Another relatively new fact is the methodology uses of the laser for par­ticle size analysis. <![CDATA[<b>Impact of sewage sludge and mineral fertilizers application in soils un­der pasture from the Alentejo region</b>]]> http://www.scielo.mec.pt/scielo.php?script=sci_arttext&pid=S0871-018X2010000100015&lng=en&nrm=iso&tlng=en Avaliaram-se as alterações nos indicado­res do solo pH em água, MO e N totais, catiões de troca, P, K, Cu e Zn “assimilá­veis”, metais pesados (Cd, Cr, Cu, Ni, Pb e Zn) e bactérias de origem fecal, entre 2004 e 2007, em dois campos experimentais com pastagens, por efeito da aplicação de lama residual urbana (LRU) e da fertilização mineral. As modalidades incluíram as com­binações de dois tipos de pastagem (natural e semeada) com três tratamentos (0, LRU e Adubação), na Herdade do Revez (Luvisso­los e Leptossolos Háplicos) e com quatro tratamentos (0, LRU, LRU+Calagem e Adubação+Calagem), na Herdade da Cri­méia (Luvissolos Férricos). Foram os teores médios de MO total e P “assimilável” as características químicas, comuns aos solos dos dois campos, em que o efeito benéfico das LRU na camada super­ficial foi significativo (P ≤ 5%). A aplicação de LRU também induziu os maiores acrés­cimos significativos de N total e de Mg de troca no solo da Herdade do Revez. A cala­gem elevou o pH e o teor de Mg de troca do solo, na Herdade da Criméia. As LRU não contaminaram os solos com metais pesados. Os níveis populacionais de coliformes e de enterococos fecais aumentaram, logo após a aplicação das LRU, para decrescerem pro­gressivamente ao longo do tempo, igualan­do-se aos das testemunhas.<hr/>We evaluated the changes in the soil indi­cators pH in water, total OM and N, ex­changeable cations, available P, K, Cu, and Zn, heavy metals (Cd, Cr, Cu, Ni, Pb, and Zn), and faecal origin bacteria, between 2004 and 2007, as affected by sewage sludge (SS) application and mineral fertili­sation in two field experiments with pas­tures. The treatments were the combinations of two types of pasture (natural and sown) with three fertilisation treatments (0, SS, in­organic fertilisers) in the experiment of Herdade do Revez (Haplic Luvisols and Haplic Leptosols), and four fertilisation treatments (0, SS, Liming+SS, and Lim­ing+inorganic fertilisers) in Herdade da Criméia (Ferric Luvisols). The OM and available P contents were the chemical properties that significantly in­creased (P ≤ 5%) in the soil surface layer of both field experiments. The SS application also caused the highest significant increases in soil total N and exchangeable Mg con­tents in Herdade do Revez. Liming in­creased soil pH and exchangeable Mg, in Herdade da Criméia. The SS did not pollute the soils with heavy metals. The bacterial populations of faecal origin increased im­mediately after the SS application, but pro­gressively decreased as time went by, reach­ing values similar to the controls. <![CDATA[<b>Fertility and heavy metal contents of soils in the tropical agroecosys­tems of the Dominican Republic-Haiti frontier zone</b>]]> http://www.scielo.mec.pt/scielo.php?script=sci_arttext&pid=S0871-018X2010000100016&lng=en&nrm=iso&tlng=en Se exponen los datos referidos a la cuanti­ficación de la fertilidad, MO. y metales pe­sados en la capa superficial de los suelos de 30 agroecosistemas tropicales en tres tipos de bosques (nublado, latifoliado y seco), co­rrespondientes a un territorio de marcada pobreza (suroeste de la República Domini­cana-Haití). El desarrollo de una agricultura sostenible en la zona requiere evaluar la fer­tilidad de los suelos; problema fundamental debido al cambio que sufren sus caracterís­ticas físicas y químicas cuando se talan y queman los bosques y luego se cultivan. La información respecto a los suelos del territo­rio es prácticamente nula, por lo que este trabajo constituye una aportación, especial­mente para la cuenca hidrográfica transfron­teriza del río Pedernales. Los agroecosistemas estudiados se en­cuentran mayoritariamente comprendidos entre los 1200 m de altitud y el nivel del mar y constituyen las fuentes esenciales pa­ra la alimentación humana y animal: pastos y cultivos de habichuela, maíz, sorgo, café, plátano-guineo, frutales y tubérculos.<hr/>This paper reports fertility, organic matter and heavy metal data obtained in topsoil samples from 30 tropical agroecosystems in three types of forest (rain, latifoliated and dry) in an area of extreme poverty (SE Do­minican Republic-Haiti). For sustainable ag­ricultural practice in this zone, soil fertility needs to be first assessed since this factor has been severely compromised by changes in the physical and chemical properties of the soil induced by the felling and burning of trees to make way for crops. Information on the soils of the region is practically null. This study focuses mainly on the transfrontier basin of the Pedernales River. The agroecosystems examined occur from an altitude of 1200 m to sea level and are the main food sources for human and animal consumption: bean, corn, sorghum, coffee, Guinea banana, fruit trees and tu­bers. <![CDATA[<b>Dynamics of organic matter in the Nature Reserve El Hondo de Elche-Crevillente (Spain)</b>]]> http://www.scielo.mec.pt/scielo.php?script=sci_arttext&pid=S0871-018X2010000100017&lng=en&nrm=iso&tlng=en Se estudió la variabilidad espacio­temporal de carbono orgánico en suelos del Parque Natural El Hondo de Elche-Crevillente en relación con la evolución en el tiempo y con el tipo de cubiertas vegetales. A su vez, se analizan los posi­bles cambios en el tiempo asociados al uso y a la gestión del territorio. Los resul­tados mostraron diferencias significativas (ANOVA p<0,05) entre cubiertas superfi­ciales y periodos de muestreo. La gran diversidad de cubiertas y el uso antrópico de las mismas deja de manifiesto las gran­des diferencias espacio-temporales en los contenidos de carbono orgánico de estos suelos y las posibilidades de secuestro de carbono que presentan los distintos medios edáficos en un mismo entorno natural.<hr/>The space-temporary organic carbon variability was studied in soils from Na­ture Reserve El Hondo in relation with its time evolution and with the vegetation covers. At the same time, the possible changes produced along the time associ­ated with the use and management of the territory were analyzed. The results re­vealed significant differences between su­perficial covers and periods of sampling (ANOVA p<0.05). The great diversity of covers and the anthropic use manifested the great space-temporary differences in the organic carbon content of these soils and the possibilities of sequestration of carbon in different soils present at the same environment. <![CDATA[<b>Assessment of soil vulnerability to erosion by a fuzzy logic model</b>]]> http://www.scielo.mec.pt/scielo.php?script=sci_arttext&pid=S0871-018X2010000100018&lng=en&nrm=iso&tlng=en Se presenta un modelo simplificado para evaluar la vulnerabilidad de suelos a proce­sos degradativos, tales como la erosión. Es­tá basado en el empleo de la lógica borrosa para operar con variables predictivas con­tinuas estimadas a partir de imágenes de te­ledetección y modelos digitales de eleva­ciones. Combina variables explicativas re­lativas al estado de la cubierta vegetal y di-versos parámetros topográficos. Las esti­maciones se realizan mediante un sistema de decisión implementado en un sistema de información geográfica (SIG), obteniéndo­se mapas de vulnerabilidad que pueden ser actualizados con nuevas imágenes de saté­lite. La zona estudiada se localiza en el su­reste peninsular, caracterizado por un clima Mediterráneo semiárido. Se estimaron altas tasas de vulnerabilidad para todas las esti­maciones realizadas, en relación a los um­brales máximos y mínimos esperables. Se estudio la respuesta de los cambios de vul­nerabilidad en relación a los cambios de clases de erosión actual a potencial según el modelo USLE. Se estimó una alta corre­lación entre los cambios de clases de ero sión y los cambios de estimaciones de vul­nerabilidad.<hr/>A simplified fuzzy logic model to assess soil vulnerability to degradation processes, such as soil erosion, is presented. The model is based on the use of fuzzy logic to operate with explanatory continuous variables esti­mated from remote sensing images and digi­tal elevation models. It combines explana­tory variables concerning the state of vege­tation cover and topographic parameters. The estimations are made by a decision sys­tem implemented in a geographic informa­tion system (GIS). Output vulnerability maps can be updated with new satellite im­ages. The study area is located on the south­east Iberian Peninsula, characterized by a semiarid Mediterranean climate. It was found high vulnerability for all estimations in relation to the expected maximum and minimum thresholds. Responses of the vulnerability changes in relation with changes of existing classes of potential erosion (based on the USLE) were analysed. It was considered a high correlation between changes in classes of soil erosion and changes in vulnerability estimations. <![CDATA[<b>Making use of mud from marble cutting and polishing to recuperate rubble marble</b>]]> http://www.scielo.mec.pt/scielo.php?script=sci_arttext&pid=S0871-018X2010000100019&lng=en&nrm=iso&tlng=en En la regeneración de las escombreras de las explotaciones de Mármol de Macael (Almería), las elevadas pendientes (> 60%) y el marcado contraste textural entre los fragmentos de estériles (Φ medio ≈ 2 cm) y el suelo aportado en superficie (Φ medio ≈ 30 µm), condiciona que los gruesos poros de los estériles carezcan de capacidad de succión, lo que hace que se comporten como impermeables, y en el suelo adiciona­do se origina un flujo en embudo que, cuan­do aflora en superficie, erosiona y rompe la manta orgánica de protección. Para evitar dicha erosión, los gruesos poros de la escombrera se rellenaron con lodo de corte y pulido del mármol. El nuevo sistema incrementó la succión y el agua retenida por unidad de superficie, y disminuyó el déficit hídrico de la vegetación implantada y el flu­jo en embudo y, por tanto, los procesos de erosión.<hr/>In the regeneration of the rubble marble quarrying in the region of Macael (Almería), the steep slopes (>60%) and marked textural contrast between the pores of the sterile fragments (average Φ≈ 2 cm) and those of the superficial soil (average Φ ≈ 30 µm), determine that the extremely large pores of the sterile materials lack suc­tion capacity and are therefore impermeable. As a result, in the superficial soil funnel flow occurs, causing erosion when it comes to the surface, and breaking the organic protection. To avoid this phenomenon, the large pores of the slag heap are filled with the sludge arising from marble cutting and polishing. This new system increased suction capacity and water retention by surface unit, and di­minished the hydric deficit of the vegetation and the funnel flow effect, thus reducing the erosion process. <![CDATA[<b>Biomass production model for lime amended acid <i>raña-</i>soils</b>]]> http://www.scielo.mec.pt/scielo.php?script=sci_arttext&pid=S0871-018X2010000100020&lng=en&nrm=iso&tlng=en Se han realizado unos ensayos de campo de dos años de duración encaminados a la corrección de la acidez de un Typic Palexe­rult, de las formaciones de raña de la mese­ta norte de la provincia de León (España). El cultivo ensayado fue una variedad local de centeno, empleándose como materiales calizos en la enmienda del suelo el yeso, do­lomita, caliza y espumas de azucarería, con dosis de 6000 kg ha-1 de CaCO3 equivalente. Además de la analítica general, se determi­naron las formas de Al solubles y fácilmente intercambiables (Al-CaCl2), además del Al extraído con KCl y con BaCl2. Los modelos de regresión lineal múltiple de la producción total de biomasa demuestran que durante el primer año son el Al-CaCl2, pH y CICE los parámetros más explicativos de la varianza (R² = 0,82). Por el contrario, durante el segundo año de cultivo son el Al-KCl y el porcentaje de saturación de bases las varia­bles más correlacionadas con la producción (R² = 0,80).<hr/>Field trials were carried out over a pe­riod of two years, aimed at correcting the acidity of a Typic Palexerult in raña for­mations in the northern mesa of León province (Spain). Gypsum, dolomite, limestone and sugar foam waste were em­ployed as liming materials to correct soil acidity, incorporating 6000 kg of CaCO3 equivalent per ha-1, and crop trials were carried out using a local variety of rye. In addition to carrying out a general analy­sis, soluble and easily exchanged forms of A1 were identified (Al-CaCl2), as was A1 extracted using KC1 and BaCl2. Multiple linear regression models for total biomass production show that in the first year, variance (R² = 0.82) was largely ex­plained by the parameters Al-CaCl2, pH and CECE. However, in the second year of crop trials, production was most closely correlated with the variables Al-KCl and base saturation percentage (R² = 0.80). <![CDATA[<b>Soil environmental quality related to different soil uses in a semiarid zone (Murcia SE Spain)</b>]]> http://www.scielo.mec.pt/scielo.php?script=sci_arttext&pid=S0871-018X2010000100021&lng=en&nrm=iso&tlng=en La agricultura intensiva y las activida­des mineras se encuentran entre las prin­cipales fuentes de contaminación del sue-lo ocasionando con frecuencia la acumu­lación en el mismo de sales solubles, nu­trientes, metales pesados, etc., con la con­siguiente pérdida de calidad del mismo. Este trabajo plantea conocer la situación de los suelos de un área de Murcia (SE España) bajo diferentes usos y parcial­mente afectada por residuos mineros. Los resultados apuntan a que los usos conside­rados, provocan una disminución de cali­dad del suelo. Así, hay una mayor presen­cia de sales solubles (Conductividad Eléc­trica: 3,3-1,9 dS m-1), NO3 (126,5-51,1 mg kg-1) y P asimilable (29,6-2,4 mg kg-1) en los suelos cultivados frente a los no cultivados. Además, gran parte de las muestras presentan niveles de metales pe­sados que superan, ampliamente en oca­siones, los valores de referencia maneja­dos habitualmente: Cd: 10,2 mg kg-1; Cu: 85,2 mg kg-1; Mn: 2307,8 mg kg-1; Pb: 6793,0 mg kg-1; Zn: 4610,0 mg kg-1<hr/>Intensive agriculture and mining activi­ties are among the soil uses that cause soil contamination because of the accumula­tion of soluble salts, nutrients, heavy met­als, etc. and consequently a loss of soil quality. This study set out to assess the condition of some cultivated and unculti­vated soils in an area of Murcia (SE Spain), known to be partially affected by mine acid materials. The results confirm that the cited activities have lead to a loss of soil quality, limiting their future use. Higher soluble salt (Electrolytic Conduc­tivity: 3,3-1,9 dS m-1), NO3 (126,5-51,1 mg kg-1) and available P (29,6-2,4 mg kg­1) concentrations were measured in the cultivated soils. In addition, many of the soil samples studied presented high levels of heavy metals which exceeded the val­ues usually taken as reference values: Cd: 10,2 mg kg-1; Cu: 85,2 mg kg-1; Mn: 2307,8 mg kg-1; Pb: 6793,0 mg kg-1 and Zn: 4610,0 mg kg-1 . <![CDATA[<b>Study of the effect of olive mill waste "alperujo" addition on the persis­tence of diuron in olive groves</b>]]> http://www.scielo.mec.pt/scielo.php?script=sci_arttext&pid=S0871-018X2010000100022&lng=en&nrm=iso&tlng=en El objetivo de este trabajo ha sido estu­diar el efecto de la aplicación de alperujo (residuo de almazara) sobre la persisten­cia y el movimiento del herbicida diuron [3-(3,4-diclorofenil)-1,1-dimetilurea] en un olivar en Mengíbar (Jaén, España). La parcela se dividió en 2 subparcelas, un en la que no se aplicó enmienda al suelo y otra donde se aplicó alperujo (18000 kg ha-1). Tras la aplicación del herbicida a una dosis de 2 kg/ha se tomaron muestras de suelo por triplicado en cada subparce­la, a distintas profundidades y distintos días desde la aplicación de diuron. Des­pués de secar, limpiar las muestras de sue-lo y tamizarlas, se procedió a la extrac­ción de diuron con metanol y se analizó por HPLC. Se observó una mayor canti­dad de diurón en el suelo enmendado que en el suelo no enmendado en todas las muestras. Sin embargo, la movilidad de diuron no aumentó con el tiempo en el suelo enmendado.<hr/>The aim of this work was to study the ef­fect of "alperujo" (olive mill waste) on the persistence and the mobility of the herbicide diuron [3-(3,4-dichlorophenyl)-1,1-dime­thylurea] in an olive grove from Mengíbar (Jaén, Spain). The plot was divided in two subplots, one where no amendement was applied and another one where "alperujo" was applied to the soil (18.000 kg ha-1). Af­ter herbicide application at a rate of 2 kg/ha, three replicates of soil were sampled at each subplot, at different depths and different days after diuron application. After drying, cleaning and sieving samples diuron was extracted with methanol and the extracts were analyzed by HPLC. Higher amounts of diuron were recovered from amended soil than from non amended soil in every sam­ple. However, diuron mobility in amen-ded soil did not increase with time. <![CDATA[<b>Uranium concentration in plants developed on agricultural soils and waste dumps in Cunha Baixa mine site (Mangualde)</b>]]> http://www.scielo.mec.pt/scielo.php?script=sci_arttext&pid=S0871-018X2010000100023&lng=en&nrm=iso&tlng=en Neste trabalho avalia-se e comparara-se a concentração e capacidade de bioconcentra­ção (CB) do urânio em diversas espécies vegetais (parte aérea) que se desenvolveram em solos de escombreira (Pinus pinaster, Cytisus striatus, Cytisus multiflorus) e culti­vadas (Zea mays L., Phaseolus vulgaris L., Lactuca sativa L.) em solos da zona agríco­la, envolvente à área mineira da Cunha Bai­xa (Mangualde). As espécies colonizadoras da escombreira estão bem adaptadas ao substrato, sendo o Pinus pinaster aquela que mais urânio concentrou na parte aérea (13,9 mg kg-1) podendo, juntamente com as espé­cies do género Cytisus, contribuir para a estabilização dos resíduos mineiros, ainda com elevada concentrações em urânio total e disponível (118 mg kg-1 e 43 mg kg-1, res­pectivamente). Entre as espécies cultivadas destaca-se a Lactuca sativa que concentrou, em média, 5,37 mg kg-1 de urânio (peso seco). Nenhuma das espécies estudadas se revelou acumuladora deste elemento (CB < 1), mesmo em situação de água de rega e solo ainda bastante contaminados.<hr/>The uranium concentration and the bioco­centration capacity (BC) in several plant species (aboveground part) were evaluated and compared among species grown on soils developed on waste materials (Pinus pinaster, Cytisus striatus, Cytisus multiflo­rus) and agricultural soils (Zea mays L., Phaseolus vulgaris L., Lactuca sativa L.) from the surrounding area of Cunha Baixa mine (Mangualde). The species colonizing waste materials are well adapted to the substratum, which contains high total and available uranium concentration (118 mg kg-1 and 43 mg kg-1 , respectively). Pinus pinaster concentrated more uranium (13.9 mg kg-1) than the spe­cies of genus Cytisus. As a consequence, and also due to the effective vegetation cover these plants can contribute to the sta­bilization of mining wastes dumps. Lactuca sativa concentrated more uranium (on ave­rage, 5.37 mg kg-1 dry weight) than the other cultivated plants. None of the studied species was uranium accumulator (BC <1), even if they are growing in high-contaminated soils and irrigated with con­taminated water. <![CDATA[<b>Biogeochemistry evaluation of soils and arbutus trees in the Panasqueira mine area</b>]]> http://www.scielo.mec.pt/scielo.php?script=sci_arttext&pid=S0871-018X2010000100024&lng=en&nrm=iso&tlng=en As Minas da Panasqueira são uma das mais importantes minas em laboração em Portugal. Ao longo de 100 anos de explora­ção de tungsténio, cobre e estanho produzi­ram-se resíduos que foram amontoados à superfície, em escombreiras, provocando impactos ambientais elevados. Este trabalho teve como objectivo o estudo biogeoquími­co da envolvente das Minas da Panasqueira através da avaliação de solos e plantas de medronheiro (Arbutus unedo L.). Os solos apresentam-se contaminados (mg kg-1) em As (922), Cd (3), Cu (215), Pb (77), W (138) e Zn (260). Nas plantas, apenas o cádmio ocorre em concentrações médias (1,53 mg kg-1) acima do limite tolerável pela generalidade das plantas, no entanto, nenhuma planta apresentava sinais de toxi­cidade. O medronheiro parece ser tolerante às elevadas concentrações totais e da frac­ção disponível (solução DTPA) desses ele­mentos nos solos, podendo por isso, ser usado em programas de fitoestabilização e para aproveitamento dos frutos com o objectivo de produzir aguardente.<hr/>Panasqueira mine is one of the most im­portant mines in Portugal. Over the last cen­tury exploration of tungsten, copper and tin has contributed to produce many waste ma­terials that constitute tailings with huge di­mensions generating high visual and chemi­cal impacts. The objective of this work was to study the biogeochemical impact of min­ing on the soils and arbutus trees (Arbutus unedo L.) in this area. Soils developed on waste materials or hosted rocks are contaminated with (mg kg-1) As (922), Cd (3), Cu (215), Pb (77), W (138) and Zn (260). In plants, cadmium is the only element that exceeded the vege­tation tolerant limit, but none of the sampled plants showed visual signs of toxicity. Ar­butus tree seems to be tolerant to the high soil concentrations (total and available frac­tion) of the hazardous elements. Therefore arbutus trees can be used in phytostabiliza­tion as a soil remediation strategy. Further studies could also allow the use of their fruits for alcohol production. <![CDATA[<b>Use of PESERA and MEDALUS models to assess soil erosion risks and land desertification in Vale do Gaio watershed</b>]]> http://www.scielo.mec.pt/scielo.php?script=sci_arttext&pid=S0871-018X2010000100025&lng=en&nrm=iso&tlng=en Neste trabalho testaram-se duas metodo­logias de avaliação dos riscos de erosão do solo e de desertificação na bacia hidrográfi­ca de Vale do Gaio (513 km²), localizada no Alentejo. Os solos dominantes na bacia são os Cambissolos, Luvissolos e Regossolos. Os sistemas de Montado de Azinho e Sobro e os sistemas agrícolas de sequeiro domi­nam, por sua vez, a ocupação dos solos. O risco de erosão foi avaliado por estimativas das perdas do solo por erosão hídrica, atra­vés do modelo PESERA. As áreas em risco de desertificação foram determinadas com base na metodologia MEDALUS. As três classes mais representativas de perdas do solo por erosão hídrica, com base nos dados meteorológicos de 2001-2006, foram: <0,5 t/ha/ano em 32,1% da área; 5-10 t/ha/ano em 23,3% da área; e 10-20 t/ha/ano em 16,9% da área. Quanto ao risco de desertifi­cação, considerando o mesmo período de tempo, a área da bacia foi assim classifica­da: 1,8% como não ameaçada; 3,9% como potencial; 68,4% como frágil; e 25,9% como crítica à desertificação.<hr/>In this study two methodologies were tested to assess soil erosion and land deserti­fication risks in Vale do Gaio watershed (513 km²), located in the Alentejo region. Cambisols, Luvisols, and Regosols are the dominant soils in the watershed. Oak tree Mediterranean woodland, Agricultural crops and pastures are the major land uses. Soil erosion risks were assessed by estimating soil loss by water erosion with the PESERA model. Land area at risk of desertification was determined based on the MEDALUS methodology. Based on meteorological data from the period 2001-2006, the three most representative classes of soil loss by water erosion were: <0.5 t/ha/year in 32.1% of the area; 5-10 t/ha/year in 23.3% of the area; and 10-20 t/ha/year in 16.9% of the area. Considering the same time period, the land area at risk of desertification was classified: 1.8% as none threatened; 3.9% as potential; 68.4% as fragile; and 25.9% as critical to desertification. <![CDATA[<b>Tillage techniques impact on soil conservation and on maize yield irri­gated by center pivot in a Fluvisol</b>]]> http://www.scielo.mec.pt/scielo.php?script=sci_arttext&pid=S0871-018X2010000100026&lng=en&nrm=iso&tlng=en Num Fluvissolo com textura mediana e declive <0,2 %, compararam-se, entre 2002 e 2004, os valores da humidade do solo, escoamento superficial, perda de solo e pro­dução de grão, numa área com milho regado por rampa rotativa e sob diferentes técnicas de mobilização do solo (convencio­nal+covachos, convencional e reduzida). Nas modalidades sujeitas a mobilização convencional+covachos observaram-se valores médios da humidade do solo mais elevados (P<0,001), um menor escoamento superficial, menor perda de solo e acrésci­mos de produção de milho-grão de 4 Mg/ha (P<0,05). Nas modalidades sujeitas a mobi­lização convencional e a mobilização redu­zida, os valores médios de escoamento superficial variaram entre 46 a 57 % das dotações aplicadas, respectivamente. As perdas de solo foram cerca de 100 kg/ha por rega, não se verificando diferenças entre aquelas modalidades. A metodologia CRESP (Classes de Risco de Escoamento Superficial) permitiu obter previsões razoá­veis do escoamento superficial potencial associado às condições de aplicação de água e de solo.<hr/>In a maize growing area, with a medium textured Fluvisol, a slope <0.2 %, irrigated by center-pivot, and subjected to different soil tillage techniques (conventional tillage, reduced tillage, and tillage reservoirs) soil water content, runoff, soil loss, and yield production values were compared, from 2002 to 2004. The plots with tillage reser­voirs presented significantly (P<0.001) higher soil water content, minimal runoff and soil loss, and a yield production 4 Mg/ha higher (P<0.05) than in the other plots. Runoff medium values in the plots with conventional and reduced tillage were 46 and 57 % of the water application, re­spectively. Soil loss was very similar in these two tillage practices, presenting me­dium values per irrigation, during the 3 years, of 100 kg/ha. CRESP methodology provided reasonable predictions of potential runoff considering the water application conditions and soil type. <![CDATA[<b>Advantages of Information and Communication Technologies (ICT) use in the teaching/learning process of Soil Pollution subject</b>]]> http://www.scielo.mec.pt/scielo.php?script=sci_arttext&pid=S0871-018X2010000100027&lng=en&nrm=iso&tlng=en Se pusieron de manifiesto las ventajas de la enseñanza de la materia Contamina­ción de Suelos mediante el uso de las TIC, adaptando la metodología al espacio europeo de educación superior, respecto al sistema tradicional. Este evidenció un 20% de abandono, gran inasistencia a las clases teóricas, seminarios y tutorías, conduciendo a que el 35% no superasen la materia. Los resultados del sistema ensa­yado fueron que los alumnos adquirieron las habilidades y competencias necesarias, la asistencia a las actividades práctica­mente total, todos realizaron los trabajos encomendados, conduciendo a la supera­ción de la materia con buenas calificacio­nes. La observación directa por el profe­sor en tutorías y seminarios, la participa­ción en actividades docentes, los objeti­vos, competencias y destrezas consegui­dos, la realización de los trabajos teóricos y prácticos, la capacidad de interpretación y tratamiento de los datos, la habilidad para extraer conclusiones y su exposición pública indicó un buen conocimiento de la materia.<hr/>It was highlighted advantages in the teaching of the subject “Soil Pollution” through the use of ICTs, adapting the meth­odology to the European Higher Education Area, with respect to the traditional teaching method. It showed 20% of neglect, absence of large lectures, seminars and tutorials, leading to 35% does not exceed the subject. The results of the system tested were that students ac­quired the necessary skills and competence, assistance for the activities almost complete, all carried out their work, leading to over­coming the subject with good grades. Direct observation by the teacher in tutorials and seminars, participation in educational activi­ties; objectives, competencies, and skills ac­quired; the execution of theoretical and prac­tical work; the ability of processing and in­terpretation of data, the ability to draw con­clusions and his public presentation showed a good knowledge of the subject. <![CDATA[<b>Composting cattle slurry solid fraction with Italian ryegrass straw (<i>Lo­lium multiflorum</i> Lam.) or gorse (<i>Ulex europaeus</i> L.)</b>]]> http://www.scielo.mec.pt/scielo.php?script=sci_arttext&pid=S0871-018X2010000100028&lng=en&nrm=iso&tlng=en A fracção sólida do chorume (FSC) de uma exploração de pecuária leiteira intensi­va foi compostada com adição de doses crescentes de palha de azevém ou de tojo, em pilhas estáticas com três revolvimentos. A temperatura aumentou na FSC até 65 ºC após o primeiro revolvimento mas as tempe­raturas máximas registaram-se mais cedo e foram mais elevadas nas pilhas com adição de palha ou de tojo. Estes materiais aumen­taram as taxas de mineralização da matéria orgânica (MO) em todas as pilhas. No entanto, a MO potencialmente mineralizável e o teor de N orgânico nos compostos finais foram inferiores. A razão C/N diminuiu de forma semelhante para todas as pilhas de 32-38 no início do processo para 13-17 no final da compostagem. A baixa temperatura, a baixa razão C/N e a baixa concentração de NH4+, em combinação com o aumento da concentração de NO 3-dos compostos finais, indicaram que estes estavam estabilizados. O elevado teor de MO (784-832 g kg-1 MS) e de N total (28-35 g kg-1 MS) e a baixa condutividade eléctrica (0,72-1,16 dS m-1) sugerem que os compostados da FSC podem ser utilizados como correctivos orgânicos do solo. A utilização de palha ou de tojo contribuiu para melhor garantir a higienização do composto.<hr/>Cattle slurry solid fraction (SF) was col­lected from a dairy farm (SF) and com­posted with increasing rates of Italian rye-grass straw or gorse, in static piles turned only three times. Temperatures increased to a maximum of 65 ºC after the first turn in the pile only with SF. In contrast, higher temperatures were registered much sooner in piles mixed with straw or gorse. The ad­dition of these bulking agents to SF in­creased temperatures and also the initial rates of organic matter (OM) mineralisation. In contrast, potential OM mineralisation and organic N content decreased. The C/N ratio declined following a similar pattern for all compost treatments, from 32-38 at the beginning of the proc­ess, to a value of 13-17 towards the end of composting. Stabilized compost was obtained from raw SF feedstock as indi­cated by the low compost temperature, low C/N ratio and the small content of NH4+ combined with increased concentra­tions of NO3-. The high concentration of OM (784-832 g kg-1) and total N (28-35 g kg-1) in final composts in addition to a low electrical conductivity (0.72-1.16 dS m-1) suggests that SF composts may be ef­fective as soil amendments. The use of straw or gorse contributed to guarantee compost sanitation. <![CDATA[<b>Chemical fractionation of carbon on Acrisols with sombric horizon from South Brazil</b>]]> http://www.scielo.mec.pt/scielo.php?script=sci_arttext&pid=S0871-018X2010000100029&lng=en&nrm=iso&tlng=en Los horizontes sómbricos (subsuperfi­ciales, oscuros y con mayor contenido de C) tienen una génesis escasamente cono­cida, pudiendo funcionar como sumideros de C en condiciones subtropicales. En dos Acrisoles del Estado de Santa Catarina (S-Brasil) se ha comprobado que la máxima acumulación de formas de C ligadas a Fe y Al extraíbles con pirofosfato y oxalato se presenta en horizontes sómbricos, pero que ésta no está relacionada con procesos de podsolización, andosolización, solodi­zación o acumulación de C por condicio­nes de hidromorfía subóxica. La mayor parte de su C se presenta en formas de oxidabilidad intermedia (oxidable con K2Cr2O7, en frío, pero no con KMnO4 0,2 M). Los porcentajes de C recalcitrante (no oxidable o díficilmente oxidable) son sig­nificativos (20-45%) pero variables a pe­queñas distancias. Procesos ligados a cambios de uso del suelo con diferente lo­calización del aporte de necromasa y efec­tos de incendios de la vegetación parecen ligados a su formación.<hr/>Sombrics horizons (subsurface, dark and with a high content of C) have a genesis poorly understood and can be conceived as a potential sink of C in subtropical envi­ronments. The maximum accumulation of C bound to Fe and Al extracted by pyrophos­phate and oxalate solution was observed in sombric horizons of two Acrisols of Santa Catarina State (S-Brazil), but this is not in­dicative of podzolisation, andosolisation or solodisation processes or accumulation of C due hydromorphy conditions. Most of its C was found at intermediate wet oxidisable fraction (oxidisable with K2Cr2O7, cold, but not by KMnO4). Recalcitrant C (non­oxidisable and difficult oxidisable) was an important pool (20-45%), but variable into profile. Changes on land use with different input of necromass and vegetations fire ef­fects seem to be involved in its formation. <![CDATA[<b>Prediction of soil quality in areas irrigated with saline waters</b>]]> http://www.scielo.mec.pt/scielo.php?script=sci_arttext&pid=S0871-018X2010000100030&lng=en&nrm=iso&tlng=en Neste trabalho pretendeu-se prever a sali­nização e sodicização de dois solos com diferentes texturas, quando regados com águas salinas combinadas com fertirrigação diferenciada e após subsequente lavagem no período Outono-Inverno. A condutividade eléctrica do extracto de saturação e da solu­ção do solo foi usada como indicador de salinidade. A percentagem de sódio de troca (ESP) e razão de adsorção de sódio (SAR) foram os indicadores usados para caracteri­zar a sodicidade do solo. As relações entre indicadores foram analisadas por regressão múltipla. Os melhores resultados de previ­são foram encontrados para o indicador SAR no solo de textura mediana e nos períodos após a rega e a lavagem, enquanto que no solo de textura grosseira foram observados no período após lavagem. Verificou-se que o azoto aplicado contribui para a salinidade da solução do solo quando a água de rega contém baixo teor em sais. Como regra, à medida que a qualidade da água de rega se reduz, o azoto contribui para diminuir a salinidade da solução do solo.<hr/>This work aims predicting salinization and sodification in two soils with different textures when they are irrigated with saline waters combined with different fertirrigation levels, and after the fall/winter rainfall washout of the soil. The electrical conduc­tivity of the saturation paste and of the soil solution was used as soil salinity indicator. The exchangeable sodium percentage (ESP) and sodium adsorption ratio (SAR) were used to characterize soil sodicity. Relation­ships between the indicators were studied with multiple regression analysis. The re­sults reveal that better predictions are ob­tained when the indicator SAR is used for the medium textured soil and when the irri­gation season and the rain washout period are taken into consideration, but for the coarse textured soil such predictions are best obtained only after the rain period. The ap­plied nitrogen also contributes to soil solution salinity only when low salt content is observed in the irrigation water. As a gen­eral rule, as the water quality decreases, ni­trogen applications contribute to diminish the soil solution salinity. <![CDATA[<b>Organoclay-based formulations to reduce the environmental impact caused by herbicides commonly applied to olive groves</b>]]> http://www.scielo.mec.pt/scielo.php?script=sci_arttext&pid=S0871-018X2010000100031&lng=en&nrm=iso&tlng=en Los repetidos episodios de contaminación de aguas superficiales y subterráneas origi­nados por herbicidas utilizados en el cultivo del olivar son motivo de una gran preocupa­ción en muchas regiones mediterráneas. El hecho de que la mayoría de las formulacio­nes comerciales de herbicidas contengan las materias activas en una forma inmediata­mente disponible acentúa el riesgo de pérdi­das por transporte de los herbicidas que se aplican al olivar y, por consiguiente, el ries­go de contaminación de aguas adyacentes. En este trabajo se presenta la preparación de formulaciones de liberación lenta de tres herbicidas (diurón, terbutilazina y MCPA), muy utilizados en el control de malas hier­bas en el olivar, a partir del soporte de los mismos en una montmorillonita modificada con cationes hexadeciltrimetilamonio. Pos­teriormente, se ha evaluado la capacidad de las formulaciones preparadas de reducir la velocidad de liberación de los herbicidas en medio acuoso y de retrasar su lixiviación a través de columnas de suelo, en compara­ción a formulaciones comerciales conven­cionales de los herbicidas. Los resultados sugieren la utilidad de las formulaciones desarrolladas para reducir las pérdidas por transporte de los herbicidas estudiados tras su aplicación a suelos de olivar.<hr/>Ground and surface water contamination by herbicides commonly applied to olive groves is a matter of current concern in Mediterranean regions. The fact that most commercial herbicide formulations in cur­rent use contain the herbicide in an immedi­ately available form that is readily released into the environment exacerbates the risk of ground and surface water contamination by rapid herbicide transport losses. In this work, we prepared slow release formula­tions of three herbicides (diuron, terbuthy­lazine, and MCPA) widely applied to olive groves by preadsorbing the herbicides on hexadecyltrimethylammonium-modified montmorillonite. Then, we evaluated the ability of the organoclay-based formulations to slow the release of the herbicides into wa­ter and to reduce their leaching through soil columns, as compared to conventional commercial formulations containing the herbicides in a readily available form. The results indicated that organoclay-based for­mulations can be useful to reduce the mobil­ity of the assayed herbicides after applica­tion to soils such as those typically used for olive growing in Mediterranean regions. <![CDATA[<b>Spatial variability of soil physical and hydrological characteristics in re­lation to the productivity of bean (<i>Phaseolus vulgaris L</i>) irrigated under no-tillage system</b>]]> http://www.scielo.mec.pt/scielo.php?script=sci_arttext&pid=S0871-018X2010000100032&lng=en&nrm=iso&tlng=en Se estudió la variabilidad espacial del sue-lo con una producción de fréjol irrigado ba­jo un sistema de siembra directa, el objetivo fue evaluar la dependencia espacial de los atributos físico-hídricos del suelo relacio­nándolos con la variabilidad espacial de la producción del fréjol. Fue sembrada una parcela y demarcados 60 puntos muéstrales en una malla de 3 x 3 m. Fueron colectadas muestras sin disturbar para determinación de la densidad del suelo, en el campo se de­terminaron la resistencia del suelo a la pe­netración y la conductividad hidráulica satu­rada. La dependencia espacial fue evaluada por el método geoestatístico del krigeado puntual. Los resultados obtenidos mostraron que las regresiones obtenidas entre mapas fueron significativas, siendo que la densidad del suelo y la resistencia del suelo a la pene­tración se correlacionaron negativamente con la producción y la conductividad hidráulica saturada se correlacionó positi­vamente.<hr/>The spatial variability of a soil used for bean production under an irrigated no-tillage system was studied. This study aimed to evaluate the spatial dependence of soil physical and hydrological characteristics in relation to the spatial variability of the irri­gated bean yield. For that reason, 60 sam­pling points were planted and demarcated in a 3 x 3 m grid. Disturbed samples were col­lected for determining soil density. In the field, soil resistance to penetration and satu­rated hydraulic conductivity were deter­mined. The spatial dependence was ana­lyzed by geostatistics using punctual kriging. According to the results, it is possi­ble to observe that the obtained regressions among maps were significant; soil density and resistance to penetration were nega­tively related to the yield, while the saturated hydraulic conductivity was related positively. <![CDATA[<b>Effect of temperature, pH and Hg<sup>2+ </sup>and Pb<sup>2+ </sup>traces in dehydrogenaseand urease activities of a soil from Évora region</b>]]> http://www.scielo.mec.pt/scielo.php?script=sci_arttext&pid=S0871-018X2010000100033&lng=en&nrm=iso&tlng=en As actividades das enzimas no solo são um importante indicador da sua qualida­de. Neste estudo procedeu-se à caracteri­zação da actividade enzimática de desi­drogenases (EC 1.1.1) e da urease (EC 3.5.1.5) de um solo sob Olea europeae L. da região de Évora. As constantes cinéti­cas Km e Vmáx, foram determinadas usando como substratos o cloreto de p­-iodonitrotetrazolio (INT) e a ureia, res­pectivamente. Foi avaliado o efeito nas referidas actividades provocado pelo pH, temperatura e vestígios de Hg2+ e de Pb2+. As actividades máximas obtiveram-se a pH = 8,5 e 40 ºC, com Km= 0,5 mM e Vmáx = 5,4 µmol min-1 g-1, para a activida­de de desidrogenases e a pH = 10 e 37 ºC, com Km = 25,7 mM e Vmáx = 2,0x10-2 µmol min-1 g-1, para a urease. Estas acti­vidades foram inibidas por diferentes concentrações de Hg2+, mas apenas a acti­vidade da urease foi inibida pelo Pb2+. Estes resultados são comparáveis com os referidos na literatura para estes enzimas.<hr/>Enzyme activities are often used as in­dicator of soil quality. This study reports on dehydrogenase (EC 1.1.1) and urease (EC 3.5.1.5) activities of a soil under Olea europaea L. from Évora region. Kinetic constants Km and Vmax were determined using p-iodonitrotetrazolium chloride (INT) and urea, respectively. Effects of pH, temperature and Hg2+ and Pb2+ traces on both activities were determined. Maximal activity was obtained at pH = 8.5 and 40ºC, Km = 0.5 mM and Vmax=5,4µmol min-1 g-1 , for dehydro­genase and at pH = 10 and 37 ºC, Km = 25.7 mM and Vmax = 2.0x10-2 µmol min-1 g-1, for urease. These activities were in­hibited by different concentrations of Hg2+, but only the urease activity was in­hibited by Pb2+. Results of this study are comparable to those reported in the litera­ture for these enzymes. <![CDATA[<b>Influence of furrow length on the infiltration equation obtained by the two point method of Elliot & Walker</b>]]> http://www.scielo.mec.pt/scielo.php?script=sci_arttext&pid=S0871-018X2010000100034&lng=en&nrm=iso&tlng=en A Equação de infiltração do tipo Kostiakov pode ser determinada através do método dos dois pontos de Elliot & Walker. No entanto não existem normas para a selecção dos dois pontos. No presente trabalho foram utilizados diferentes pares de pontos ao longo de um sulco com 220m para calcular as correspon­dentes equações de infiltração. Os resultados demonstram que o expoente a da equação aumenta com o comprimento de sulco consi­derado, e com a distância até ao ponto do meio. Por sua vez, o coeficiente k tem um comportamento inverso, diminuindo com o aumento do comprimento do sulco. Assim, e por forma a que haja uma uniformidade de critérios, é recomendável que o primeiro pon­to esteja o mais próximo da meia distância entre a cabeceira e o segundo ponto.<hr/>The Kostiakov infiltration equation can be established by the two point method of El­liot and Walker. Nevertheless, there are no indications as to how the two points should be selected. In this paper different pairs of points along a 220m long furrow are used to calculate the corresponding infiltration equation. The results indicate that the expo­nent of the equation increases with the length of the furrow, and with distance to the first point. The k of the equation behaves in the opposite direction, decreasing with an increase in the length of the furrow. It is recommended that the first measurement point should be located half way between the furrow inlet and the second measure­ment point. <![CDATA[<b>Effect of runoff on suspended sediment and phosphorus loading in a headwater stream of a rural catchment (NW Spain)</b>]]> http://www.scielo.mec.pt/scielo.php?script=sci_arttext&pid=S0871-018X2010000100035&lng=en&nrm=iso&tlng=en Se determinó la carga de sedimentos en suspensión (SS) y fósforo (P) durante even­tos de lluvia-escorrentía en un arroyo de ca­becera, que drena una cuenca rural ubicada en Galicia (NO España). Asimismo, se trató de conocer las principales fuentes de SS y P exportados. Se observaron acusadas dife­rencias en la carga de SS y P entre eventos, lo cual se asocia con el volumen de esco­rrentía, así como con el desarrollo de surcos y cárcavas efímeras en parcelas de cultivo bien conectadas con la red de drenaje. La carga de SS osciló entre 0,8 y 21,0 t mientras que la de P varió entre 2,5 y 20,0 kg. El fósforo parti­culado (PP) mostró relaciones significativas con los SS, lo que indica el origen erosivo de una parte importante de P, especialmente considerando que el PP supone más de un 80% del P exportado en cada evento.<hr/>This work examines the suspended sedi­ment (SS) and phosphorus (P) load during rainfall-runoff events in a headwater stream which drains a rural catchment located in Galicia (NW Spain). Another objective is to know the major sources of SS and P ex­ported. Important differences in the SS and P load between events were found, which is associated with the runoff volume, as well as to develop of rills and ephemeral gullies in cultivated fields well connected to the drainage network. The SS load ranged be­tween 0.8 and 21.0 t, while the P load varied between 2.5 and 20.0 kg. The particulate phosphorus (PP) showed significant rela­tionship with SS, which indicates the ero­sive origin of P, especially considering that PP means more 80% of P exported each event. <![CDATA[<b>Soil quality of vineyards in the Origin Denomination Rioja: Index of overcrusting risk (FAO-PNUMA), content of organic carbon and rela­tion with soil fertility</b>]]> http://www.scielo.mec.pt/scielo.php?script=sci_arttext&pid=S0871-018X2010000100036&lng=en&nrm=iso&tlng=en El objetivo de este trabajo es evaluar en primera aproximación la calidad de los suelos de viñedo en la Denominación de Origen Calificada (D.O.Ca) Rioja. Pa­ra ello se tomaron los 30 cm superficia­les de 123 suelos de viñedo con laboreo convencional. Se analizó el carbono or­gánico, pH, C.E., carbonatos, textura, bases de cambio y P Olsen; se determinó también el índice de riesgo de formación de costra superficial (FAO-PNUMA). Según este índice FAO-PNUMA más del 50 % de los suelos tienen un riesgo medio-alto de encostramiento. El conte­nido de carbono orgánico, está por deba­jo del 1%, inferior al nivel necesario para mantenimiento de la calidad del suelo. El carbono orgánico está correlacionado con la fracción arcilla y con el P Olsen, indicando el favorable efecto de la materia orgánica en la disponibilidad del P.<hr/>The aim of this study was evaluate in first approximation the soil quality in vineyards of the Origin Denomination Rioja. For this study, soil samples were collected from 0 cm to 30 cm depth in 123 vineyards under conventional tillage, and were determined the organic carbon, pH, C.E, % carbonates, texture, ex­changeables bases and P Olsen. Also was calculated the index of overcrusting risk by FAO-PNUMA. According FAO­PNUMA index, over 50 % of the soils had a medium-high overcrusting risk. The average organic carbon content was inferior to the 1 % necessary level to maintain the quality of the soil. Also organic car­bon was correlated with the clay content and with the P Olsen, indicating the posi­tive effect of the organic matter in the P availability. <![CDATA[<b>Simulation of water dynamics in two irrigated soils</b>]]> http://www.scielo.mec.pt/scielo.php?script=sci_arttext&pid=S0871-018X2010000100037&lng=en&nrm=iso&tlng=en Simulation results for water content dis­tribution obtained with HYDRUS, RZWQM and MOHIDLAND models were compared with field data. These models differ mainly in calculating root water uptake and computing crop water requirements. Simulations were carried out in different horizons of an Hortic An­throsol and an Eutric Fluviosol, located in the Alentejo region (Portugal). Soil water content was measured, with a TDR sys­tem at different depths. Soil hydraulic properties were determined in the labora­tory, and described in HYDRUS and MOHIDLAND with the Mualem-van Genuchten, and in RZWQM with the modified Brooks and Corey equations. Reference evapotranspiration was calcu­lated with the Penman-Monteith and the Shuttleworth-Wallace method using at­mospheric data from the meteorological stations located near the field plots. Parti­tion between transpiration and evapora­tion was calculated using the Leaf Area Index values, and the RZWQM crop module. Results show a good agreement between model simulations and field measurements for the three models.<hr/>Foram comparados os resultados da simu­lação do teor de água no solo obtidos com os modelos HYDRUS, RZWQM e MOHI­DLAND com valores medidos. Estes mode­los diferem principalmente nos cálculos da extracção de água pelas raízes e das neces­sidades de água das plantas. As simulações foram realizadas para diferentes profundi­dades de um Fluvissolo Êutrico e de um Antrosolo Hórtico localizados no Alentejo (Portugal). O teor de água foi medido com um sistema TDR. As propriedades hidráuli­cas, determinadas laboratorialmente, foram descritas com as equações de Mualem-van Genuchtene e Brooks and Corey modifica­das. A evapotranspiração de referência foi calculada com os métodos de Penman-Monteith e de Shuttleworht-Wallace com dados atmosféricos medidos. A partição entre a transpiração das plantas e a evapora­ção do solo foi calculada através do Índice de Área Foliar medido e através do modelo RZWQM. Os resultados mostram boa con­cordância entre as simulações dos três modelos e os valores de campo. <![CDATA[<b>Availability of Cu, Pb and Zn in Canal Caveira and São Domingos mine areas from Iberian Pyrite Belt</b>]]> http://www.scielo.mec.pt/scielo.php?script=sci_arttext&pid=S0871-018X2010000100038&lng=en&nrm=iso&tlng=en Avaliou-se a disponibilidade do Cu, Pb e Zn nos solos das áreas mineiras de São Domingos e Canal Caveira (Faixa Piritosa Ibérica) com o objectivo de determinar a potencialidade de dispersão daqueles ele­mentos no meio. Em ambas as áreas as concentrações totais dos elementos foram elevadas e a dis­ponibilidade variou consoante as parcelas e, consequentemente, com as características dos solos. A fracção disponível de Pb é superior nos solos de Canal Caveira, contu­do para o Zn observou-se o contrário. Em ambos os solos, a fracção de Cu disponível é <0,6 % da concentração total. Nos solos das duas minas, o Zn e Cu estão maiorita­riamente associados à fracção residual enquanto que o Pb está associado à fracção residual em São Domingos e à matéria orgânica em Canal Caveira. Estas áreas mineiras apresentam baixo risco ambiental relativamente ao Cu porém, o Pb e o Zn, em função da sua disponibilidade, podem afec­tar a biodiversidade.<hr/>Several mining areas are abandoned in the Iberian Pyrite Belt (IPB) leading to important points of environmental con­tamination. The potential and immediate environmental risk and impact on public health of hazardous elements from soil can be estimated from availability analy­sis. The aim of this study was to evaluate the availability of Cu, Pb and Zn in São Domingos and Canal Caveira mining ar­eas located in the IPB. Both mining areas had high soil ele­mental total concentrations. Metals avail­ability changed with plots and, is related with soils characteristics. In Canal Caveira mine area, the Pb available frac­tion in soils was higher than in São Domingos soils however, the opposite was observed for Zn. The fractions of available Cu, in both mine soils, are <0.6 % of the total concentration. In both min­ing areas, Cu and Zn are mainly associ­ated with the residual fraction, while Pb is associated with residual fraction in São Domingos and with organic matter in Ca­nal Caveira soils. <![CDATA[<b>Characterization of composts and organic wastes for nursery substrate formulation</b>]]> http://www.scielo.mec.pt/scielo.php?script=sci_arttext&pid=S0871-018X2010000100039&lng=en&nrm=iso&tlng=en No presente trabalho procedeu-se à carac­terização físico-química e biológica de pro­dutos obtidos a partir da compostagem de diferentes resíduos orgânicos: lamas de estações de tratamento de águas residuais (ETAR), fracção orgânica de resíduos sóli­dos urbanos (RSU) e, resíduos verdes de parques e jardins. Foi ainda caracterizado um substrato comercial utilizado em vivei­ros florestais. O composto que apresentou maior limita­ção para ser utilizado na formulação de subs­tratos foi o produzido a partir da fracção orgânica de RSU devido aos elevados valores de pH e de condutividade eléctrica, e aos bai­xos valores de índice de germinação e de crescimento verificados para a espécie utili­zada, o Lepidium sativum; os compostos que apresentaram maior potencialidade para ser utilizado na formulação de substratos foram os produzidos a partir de lamas de ETAR e de resíduos verdes de parques e jardins.<hr/>Present work aimed the physic-chemical and biological characterization of products obtained from composting of several organic wastes: sewage sludge produced at wastewater treatment plants (WWTP), organic fraction of municipal solid waste (MSW) and, green waste from parks and gardens. A commercial sub­strate used at nursery plants was also characterized. The compost that presented minor po­tentiality to be used on the formulation of substrates was compost produced from organic fraction of MSW due to its high values of pH and electrical conductivity, and low values of germination and growth indexes for Lepidum sativum; composts analysed that presented high potentiality to be used on the formulation of sub­strates were those that were produced from WWTP sewage sludge and from green wastes. <![CDATA[<b>Modeling and determination of critical state of consolidation from mass-volume ratio in farmland</b>]]> http://www.scielo.mec.pt/scielo.php?script=sci_arttext&pid=S0871-018X2010000100040&lng=en&nrm=iso&tlng=en O trabalho teve por objetivo sugerir equações, as quais permitam estimar a densidade do solo (ρσp) e o volume total de poros (nσp), ambos referentes à pressão de preconsolidação (σp), propondo-os como indicadores físicos na avaliação da qualidade e do estado crítico de consolidação dos solos agrícolas. Os índices físicos foram obtidos por meio de ensaios de consolidação uniaxial de amostras indeformadas de um Nitossolo Vermelho, depois de submetidas aos seguintes estados de consistência: tenacidade, friabilidade e plasticidade. Os resultados permitiram estimar a ρσpeanσp que o solo pode atingir para que o mesmo não tenha a sua estrutura degradada. As equações mostraram-se ferramentas poderosas na avaliação da capacidade de suporte de carga dos solos podendo estimar a máxima relação de massa/volume que o solo pode atingir.<hr/>The objectives of this research was to suggest equations, to estimate the bulk den­sity (ρσp) and total porosity (nσp), on the pre-compression stress (σp), proposing them as indicators for the evaluation of the quality and the critical consolidation state of farm­land. The physical characteristics were ob­tained by uniaxial precompression tests of undisturbed samples of an Alfisol after be­ing subject to the following states of con­sistency: toughness, friability and plasticity. The results allowed estimating the ρσp and nσp which the soil can reach without having its structure degraded. The equations were shown to be powerful tools in assessing the soil bearing capacity and the maximum mass-volume ratio that may reach the ground.