Abstract: The gap between scientifically sound nitrogen (N) fertilizer application rates and the actual rates used by farmers in maize is still significant. The improvement of nitrogen use efficiency in such a highly N-demanding crop is necessary to decrease the negative effects of N fertilization. The objective was to compare the performance of different N management treatments in maize grown under semiarid Mediterranean sprinkler-irrigated conditions to the standard farmer practice. We compared an agronomically sound fixed rate of N fertilizer (FR) with a variable N rate obtained based on a soil mineral balance at pre-planting (SB) or based on a portable chlorophyll meter readings (CM) made just before tasseling. Additional treatments were a N control, without fertilizer (T0), and a non-limiting N (NL) treatment wich was typical of the current farmer practice. The study was replicated at 5 sites in one-year experiments and under 3 pre-planting soil mineral nitrogen environments (SMN, Low, Medium, and High). The results demonstrate the potential to reduce N rates from zero to 236 kg N ha−1 compared to the NL in irrigated maize fields without compromising yields in most of the situations with a subsequent increase of NUE. Averaging over sites, the use of fine-tuning N fertilizer strategies that considered field-specific conditions (SB and CM) reduced N rates (38 %) compared to the reductions under the FR strategy (26 %) relative to the NL conditions, which is the treatment closest to a typical farmer`s application rate. ; Published
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