Abstract

BRITO, L. M.; FERNANDES, A. S.  and  AMARO, A. L.. Comparison between randomized block and systematically arranged fertilizer experiments with maize (Zea mays L.). Rev. de Ciências Agrárias [online]. 2009, vol.32, n.1, pp.312-322. ISSN 0871-018X.

To compare N recovery within plots, a silage maize randomized block designed experiment was carried out, as opposed to an other experiment, with systematic arrangement of treatments, which included a con-trolled-release N fertilizer. Both experiments integrated increasing rates of an ammonium nitrate based fertilizer and composts from the solid fraction of dairy cattle slurry. Piles were composted over 105 days for the randomized experiment, with 5 and 15 turns and over 154 days for the systematic arranged experiment, with 5 turns. Although occasional effects were found on crop growth with the application of composts they were generally small or not significant compared to the addition of mineral N fertilizer. Maize yield and N uptake increased with mineral N applied from 0 to 140 kg/ha, however, a further increase to 210 kg/ha was not related to higher yield in the randomized experiment. Nevertheless, increases of mineral N between 90 kg/ha and 180 kg/ha were associated with higher yield in the systematic arranged experiment, particularly when the controlled-release fertilizer was used. Since the most efficient management practice to maximise plant uptake and minimise losses, is to synchronise the N supply with the plant demand for N, controlled-release fertilizers may be an alternative to improve N recovery by the crop, whereas composts should be applied after a long period of maturation, or sooner before sowing. In contrast to the randomized experiment, edge effects within plots appeared to be largely cancelled each other out in the systematically arranged experiment, because of the stepwise progression of the mineral N treatments.

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