Simulation of nitrogen fate for greenhouse cucumber grown under different water and fertilizer management using the EU-Rotate_N model

The objectives of this study were to compare nitrate leaching for greenhouse vegetable grown under different water and fertilizer management, and to provide the best management practices (BMPs). A greenhouse cucumber experiment with different water and nitrogen management was conducted in Shouguang County of North China from 2009 to 2010. Seven different irrigation and fertilizer treatments were designed, including five treatments with furrow irrigation: no fertilizer (CK), organic manure (OM), conventional fertilizer (farmer's practice, FP), optimal fertilizer application (OPT), crop residues + farmer practice (CN), and two with drip irrigation: conventional fertilizer (RI) and crop residues + optimal fertilizer (OPTRI). The EU-Rotate_N model was used to simulate the greenhouse cucumber growth, water movement and N fate. Results indicated that the simulated values of cucumber dry weight, N uptake, soil water content and NO3-N concentration in the soil profile all agreed well with the observed values. Also, it was revealed that the irrigation method, amounts of fertilizer input and crop residues had significant effects on nitrate leaching and nitrogen use efficiency (NUE). Compared with that under the FP treatment, the amounts of nitrate leaching under the CN and RI treatments were decreased by 26–32% and 75–80%, respectively, whilst the amount of nitrate leaching under the OPT treatment could be reduced 32–36%. Nitrate leaching under the OPTRI treatment was the least, and the reduction was 79–86%. On the other hand, NUE was increased by 2–3%, 15–18% and 40–43% under the OPT, CN and RI treatments, respectively. The largest NUE occurred under the OPTRI treatment, about 314.5–337.4 kg kg−1. It is concluded that the optimal fertilizer N, drip irrigation and straw incorporation are the effective measures for reducing N leaching and improving NUE. Amongst all the treatments, the OPTRI treatment yielded the lowest N leaching at the expense of a slight decrease in yield of greenhouse cucumber. Therefore, the OPTRI treatment should be recommended to farmers in order to reduce the risk of groundwater pollution and to develop sustainable vegetable production in the area.

► EU-Rotate_N model was calibrated and validated for greenhouse cucumber in China.
► Nitrate leaching is a main way of N loss in the vegetable production in North China.
► Optimal fertilizer and adding crop residue can effectively reduce nitrate leaching.
► Drip irrigation can significantly reduce the amount of nitrate leaching.
► Drip + optimal fertilizer + crop residues is the best management practices.