Abstract
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.
Highlights
Potato (Solanum tuberosum L.) is the fourth staple food in China with 4.91 million ha harvested area and 92 million tons of tuber production, which accounts for 28% and 25%of the world total in 2019, respectively, but the average yield is 12% lower than that of the world [1]
Potato yield is restricted by unbalanced fertilizer management [2]; for example, 55% of farmers applied N fertilizer at an unreasonable rate in northwest China based on a field survey [3]
Calibration of the DNDC and WHCNS_Veg models showed “good” agreements between the simulated and measured tuber fresh yield and above-ground biomass in the N3 treatment based on the values of normalized root mean square error (NRMSE) (5.4–11.6%), normalized average relative error (NARE) (−6.1–2.4%) (Figures 1 and S2, Table 3)
Summary
Potato (Solanum tuberosum L.) is the fourth staple food in China with 4.91 million ha harvested area and 92 million tons of tuber production, which accounts for 28% and 25%. Of the world total in 2019, respectively, but the average yield is 12% lower than that of the world [1]. Compared to the no fertilizer treatment, the yield increase is about. 8.6 t ha−1 under optimum N treatment, which is significantly greater than the increase of. 5.9 t ha−1 and 6.6 t ha−1 under optimum phosphorus (P) and potassium (K) treatments, respectively [4]. The average N recovery efficiency of a farmer’s practice was less than 30% for potato production in China [6,7] and the typical harvest index of N was
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