Moderate water deficit and nitrogen application rate are conducive to improving the nitrogen uptake and yield of greenhouse tomatoes

Abstract

Nowadays, improper irrigation and fertilization result in a waste of resources and a decrease in tomato production. In this study, we set three irrigation intervals (W1, W2 and W3 indicated upper and lower limit of irrigation of 65–75% θFC, 75–85% θFC and 85–95% θFC) and three nitrogen application rates (N1, N2 and N3 indicated nitrogen application rates of 120, 180 and 240 kg hm−2). The HYDRUS–2D model was first calibrated and validated using data collected during a two–year field investigation and then applied to explore the rules of soil water and nitrogen movement and root uptake. The Entropy weight TOPSIS model was optimized water and nitrogen management. Reliable estimates of soil nitrate nitrogen concentrations (R2 = 97%–99%, MRE = 0.05–0.19 and RMSE = 0.023–0.110), crop N uptake (R2 = 88%–99%, MRE = 0.17–0.44 and RMSE = 0.25–10.72), and soil water content (R2 = 82%–96%, MRE = 0.009–0.024 and RMSE = 0.003–0.007) were provided by HYDRUS–2D model. Based on the simulated results, the soil ammonium nitrogen was not easily affected by soil water movement and mainly distributed in 0–30 cm. W3 made soil water move deeper and carried nitrate nitrogen to accumulate in the deep soil comparison to W2 and W1. The combination of irrigation interval of 75–85% θFC and nitrogen application rate of 180 kg hm−2 improved root uptake, water use efficiency, nitrogen use efficiency and tomato yield. The evaluation result showed that N2W2 was the optimal water and nitrogen supply mode for our study. This study could promote the sustainable production of greenhouse tomatoes.