Using Dndc And Whcns_veg To Optimize Management Strategies For Improving Potato Yield And Nitrogen Use Efficiency In Northwest China

Excessive nitrogen (N) application rate led to low N use efficiency and environmental risks in a potato (Solanum tuberosum L.) production system in northwest China. Process-based models are effective tools in agroecosystems that can be used to optimize integrated management practices for improving potato yield and N use efficiency. The objectives of this study were (1) to calibrate and evaluate the DeNitrification-DeComposition (DNDC) and soil Water Heat Carbon Nitrogen Simulator of Vegetable (WHCNS_Veg) models using the measurements of potato yield, above-ground biomass, N uptake, soil moisture and temperature, and soil inorganic N based on a field experiment in northwest China (2017-2020) and (2) to explore optimal management practices for improving yield and N use efficiency under long-term climate variability (1981-2020). Both models overall performed well in simulating potato tuber yield (normalized root mean square error (NRMSE) = 5.4-14.9%), above-ground biomass (NRMSE = 6.0-14.7%), N uptake (NRMSE = 18.1-25.6%), daily soil temperature (index of agreement (d) > 0.9 and Nash-Sutcliffe efficiency (EF) > 0.8), and acceptable in-soil moisture and inorganic N content (d > 0.6 and EF > -1) for N-applied treatments. However, the two models underestimated tuber yield and soil N content for no N fertilization treatment which was partially attributed to the underestimated soil N mineralization rate under N stress conditions. The sensitivity analysis showed that the greatest tuber yield and N use efficiency were achieved at the N rate of 150-180 kg ha(-1) with 2-3 splits, fertilization depth of 15-25 cm, and planting date of 25 April to 10 May in both models. This study highlights the importance of integrated management strategies in obtaining high N use efficiency and crop yield in potato production systems.