Abstract
The biomass productivity and wheat grains efficiency is determined by nitrogen dose adjustment (full or fractioned), environmental conditions, and cropping system. The aim of this study was to improve the efficiency of N-fertilizer usage on wheat to maximize the biomass productivity and grain yield by adjusting the full or fractioned nitrogen dose in favorable and unfavorable year conditions, in succession systems with high and reduced N-residual release. In this study, two experiments were conducted between 2012 and 2014. One was to quantify the biomass productivity rate and another to determine grain yield. The experimental design was a complete randomized block, with four replications, in a 4 × 3 factorial scheme to N fertilizer rates (0, 30, 60 and 120 kg ha-1) and supply forms of the nutrient [full dose (100%) in the V3 phenological stage (third expanded leaf); fractioned (70 and 30%) at the V3 and V6 phenological stages (third and sixth expanded leaf, respectively) and; fractionated (70 and 30%) at the V3 and E phenological stages (third expanded leaf and early grain filling), ] respectively, in soybean/wheat and maize/wheat cultivation systems. The nitrogen supply in wheat through single dose or fraction indicates linear tendency over the productivity biomass daily rate-1 with the increase of N-fertilizer, regardless of a favorable and unfavorable year and system of a succession of the high and reduced N-residual release. However, in favorable years, the use of full dose on V3 stage is indicated. In the maize/wheat system, the full dose at V3 stage is more efficient, especially with higher doses of the nutrient. For grain yield, the N-fertilizer fractioning was adjusted in intermediate cropping years, while the full dose became suitable at the V3 stage in favorable years. However, in unfavorable years, nitrogen investments should be minimized, regardless of the supply form and succession system. Key words: Triticum aestivum L., succession system, optimization, regression.
Highlights
The supply of N-fertilizer for plants depends, among other factors, on the amount of soil organic matter, the decomposition of plant residues and yield expectation, which interact with each other in cropping systems (Costa et al, 2013; Mantai et al, 2015a)
The aim of this study was to improve the efficiency of N-fertilizer usage on wheat to maximize the biomass productivity and grain yield by adjusting the full or fractioned nitrogen dose in favorable and unfavorable year conditions, in succession systems with high and reduced N-residual release
In the condition of high C/N ratio (Table 3), the results suggest that the lower N-residual release for corn straw requires the need for the most intensive use of Nfertilizer, with direct application of full dose at V3 stage
Summary
The supply of N-fertilizer for plants depends, among other factors, on the amount of soil organic matter, the decomposition of plant residues and yield expectation, which interact with each other in cropping systems (Costa et al, 2013; Mantai et al, 2015a). The climatic conditions of each year (favorable or unfavorable) and the succession systems, with high or reduced N-residual release, can alter the nitrogen use efficiency in wheat yield (Arenhardt et al, 2015). Nitrogen fertilization should not be characterized by its high cost, but by the efficient use to provide productivity and sustainability (Costa et al, 2013) In this context, the possibility of splitted application of N fertilizers with adjusted doses can result in increased utilization efficiency by wheat (Espindula et al, 2010). The possibility of splitted application of N fertilizers with adjusted doses can result in increased utilization efficiency by wheat (Espindula et al, 2010) This management can be better understood and feasible, taking into account the environmental conditions and succession systems with the high and reduced release of N-residual
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