Estimating nitrogen inputs from a Kura clover living mulch system for maize production

Aims: Kura clover living mulch (KCLM) is thought to provide in-season nitrogen (N) to the cash crop. Because of interactions between cropping system and crop performance, the magnitude of in-season N inputs from KCLM cannot be quantified using common N rate research methods. We aim to quantify the timing and magnitude of these N inputs using clover biomass and decomposition data. Methods: This research measured the temporal distribution of clover biomass with intensive sampling, vertical biomass distribution using bead tracer analysis, and residue decomposition using in situ litter bags. These data were used as inputs to a model that estimated the in-season N contributions from KCLM. Results: Our results found that spring management contributed 7–23 kg N ha⁻¹ during the first 6 weeks of the growing season, while shade suppression contributed 59 – 84 kg N ha⁻¹ from mid-June to mid-October. Daily N inputs peaked on 8 August at 1.14 kg N ha⁻¹ d⁻¹. When these estimates were added to fertilizer N inputs and analyzed against crop N uptake, we found that the maize took up 88% of the total N inputs and fertilizer recovery efficiency was 56%. Conclusions: This study provides a methodology which generates estimates that may be used in research related to N cycling and management in KCLM and other legume intercropping systems.