Simulation of greenhouse cucumber growth, water and nitrogen dynamics in areas with high groundwater (HG) levels using the HG EU-Rotate_N model

Abstract

The fruit yields of cucumber are always associated with high inputs of nitrogen, which poses a risk of pollution to the environment. The EU-Rotate_{_}N model has been used widely for its good performance in the simulation of vegetable growth, water and nitrogen dynamics. However, whether the underground water level affects the performance of the EU-Rotate_{_}N model is unclearly. In this study, we modified the groundwater level algorithms to the original model and named the modified model “the HG EU-Rotate_N model”. Experiments over two years on greenhouse cucumber with four different nitrogen (N) treatments (N1-N4) were conducted in Jiangsu Province, China, which has a high groundwater level (area_HG). Both original and modified models were used to simulate cucumber growth, water movement and N fate. For the soil water content, the measured values were significantly larger than the simulated values of the original model (value_O) and closer to those of the HG model (value_HG); for the soil available nitrogen concentration (SNC), the measured values were significantly higher and lower than value_O in 0-10 cm and 10-30 cm soil layers, respectively, and were also closer to those of the values_HG. The higher SNC in the 0-10 cm soil layer indicated that a high groundwater level might increase the upwards movement of water and nitrogen in the 0-30 cm soil layer. The root mean square error, Nash Sutcliffe Efficiency and difference values show that the HG model was more applicable for area_HG than the original model. In this study, the nitrogen dosage of the N3 treatment was sufficient to meet the requirements of the cucumber growth, indicating that the fertilization recommendation according to nitrogen nutrient balance was applicable in this area.