Sen Hou ^1,2 Quanjuan Fu ² Huifeng Li ^1,2 Rui Gao ² Yugang Sun ^2* Guoqin Wei ^2*

• ¹ State Key Laboratory of Nutrient Use and Management., Jinan, China
• ² Shandong Institute of Pomology, Taian, China

To ensure higher productivity, fertilizers have been excessively applied to the fruit greenhouse soil yearly, thus resulting in the increasing risks of residual nitrate leaching in the North China Plain. In this study, a water and solute transport HYDRUS-1D model was used to evaluate the effects of using sweet corn as a catch crop on deep water drainage and nitrate leaching in a sweet cherry greenhouse soil. A three-year (2019–2021) field experiment was conducted during the rainfall season from July to September in the post-harvest of sweet cherry, when the plastic cover was removed each year. In the experiment, the five treatments were designed. The three nitrate residue levels denoted by CKR, N1R, and N2R, represented nitrate residue amounts in the soil profile of three nitrogen fertilizer levels before the harvest of sweet cherry. Two other treatments with and without sweet corn as a catch crop based on the treatments of N1R and N2R were denoted by N1RC and N2RC, respectively. The simulated results have showed that using sweet corn as a catch crop increased the evapotranspiration rate, the upward flux of water and nitrate at a 100 cm soil depth reached a maximum of 1.5 mm d-1 and 1.0 kg N ha-1d-1, respectively, and the downward movement of water and nitrate leached to deeper soil layers was reduced. Compared with CKR, the treatments with catch crops (N1RC and N2RC) reduced the amount of water drainage by 16.4% -47.7% in the 0-180cm soil profile. The average amounts of nitrate leaching in the 1.8 m soil profile during the three-year experiment were 88.1, 113.3, and 58.2 kg N ha−1 for the treatment without catch crop (N1R and N2R) and 32.3, 54.8, and 31.4 kg N ha−1 for the treatment with catch crop, respectively. The treatments with catch crops decreased the amount of nitrate leaching by 29.6%-69.1% compared with the treatments without catch crops. Sweet corn as summer catch crop can reduce nitrate leaching in the sweet cherry greenhouses. Our study has provided an effective method to reduce the risk of nitrate leaching for sweet cherry greenhouses in the North China.