Monitoring wheat nitrogen requirement and top soil nitrate for nitrate residue controlling in drylands

Abstract Nitrogen (N) fertilizer application is an essential way to keep the high yielding crop production, but nitrate-N residue in agricultural soils has attracted wide attentions due to its various environmental effects. Understanding the yield formation and its relation to the N uptake and requirement are urgently needed to reduce the nitrate-N residue for plastic mulched wheat production in drylands. A three-year location-fixed field experiment with five N rates was carried out to test the grain yield formation and N use characteristics of wheat and soil nitrate-N response to no mulch (NM) and plastic film mulch (PM) cultivations. Obtained results showed that the PM promoted the wheat growth and had higher maximum grain yield and biomass at the similar N rate, compared to the NM. Although wheat took up much more N from the soils under the PM, its N requirement for 1000 kg grain formation (NR) showed no significant difference from that of the NM, and for management of N fertilization, the same NR can be used for both cultivations in dryland. Nitrate-N content in 0–20 cm top soil (SNC) was found lower under NM than that under PM, but nitrate-N residue in 0–100 cm soil (SNR) showed no significant difference between these two cultivations. The SNR was significantly and linearly correlated with the SNC under both cultivations, and thus the SNC is able to be used to predict the SNR. Therefore, the present work provides a feasible way or an idea to use the top soil nitrate content, wheat grain yield and its N requirement to optimize the N application rates and N fertilizer recommendation for wheat production and soil nitrate-N residue control in dryland.