A comprehensive analysis of the nitrogen synchrony between cover crops release and maize uptake

Abstract

Background and aims: Quantitative analyses of the synchronybetween nitrogen (N) release from cover crops(CCs) and maize (Zea mays L.) uptake remain limited.This study aimed to i) develop a method to assess N synchrony,ii) analyze how CC species and termination datesaffect N synchrony, and iii) relate N synchrony to CCcharacteristics, maize yield, and associated N traits.Methods: We quantified N synchrony as the percentagematch between daily N release from CCs and the portionof maize N uptake not met by soil supply. This approachwas used to calculate N synchrony and excess-asynchronyfor three CCs [oat (Avena sativa L.), hairy vetch (HV,Vicia villosa Roth.), and an oat–HV mixture (Mix)] withtwo termination dates (early and late) over two seasons.Results: Nitrogen synchrony was higher in HV andMix than in oat (81%, 70%, and 23%, respectively),and higher in late terminations (~ 1 week beforemaize sowing) than early terminations (~ 4 weeksbefore sowing) (65% vs. 51%). An N accumulationof ~ 140 kg N ha−1 in CC aboveground biomass optimizedthe balance between N synchrony and excessasynchrony.N accumulation, C:N ratio, and the daysbetween CC termination and maize sowing explainedN synchrony variability (R2 ≥ 0.77). N synchrony wasnegatively related to maize yield response to N andpositively related to N use and recovery efficiencies.Conclusion: This analysis provides insights to guideCC management for improving maize yield, optimizingN fertilization, and reducing environmental N losses.