| الملخص: | Cover crops in no-tillage systems may alter soil mineral N and influence the N fertilizer use efficiency (NFUE) of subsequent maize. The hypothesis of this work is that no-tillage systems with cover crops affect nitrate, ammonium and maize NFUE in the Brazilian Cerrado. The objective was to evaluate the cover crop mineralization effect on soil N mineral and maize NFUE in a no-tillage system, with and without N topdressing. The experiment was arranged in a randomized block split-plot design. The plots were represented by cover crops (<i>Cajanus cajan</i>, <i>Crotalaria juncea</i>, <i>Raphanus sativus</i> and <i>Mucuna aterrima</i>). The subplots consisted of the application (WN) or non-application (NN) of N topdressing to maize. The soil was sampled in six layers (up to 60 cm) at the end (April) and at the beginning of the rainy season (November). NH<sub>4</sub><sup>+</sup> was lower for all cover crops and WN and NN management in April. NO<sub>3</sub><sup>−</sup> differed between seasons and cover crops in WN and NN. The lignin concentration and N uptake of <i>M. aterrima</i> were the highest compared to other species. The highest NFUE was on <i>R. sativus</i>, showing higher fertilizer dependency. In a no-tillage system with cover crops, the N topdressing fertilization needs to be improved, considering mineralization.
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