Effects of summer catch crop, residue management, soil temperature and water on the succeeding cucumber rhizosphere nitrogen mineralization in intensive production systems

Nitrogen nutrient management is crucially important in shallow-rooted vegetable production systems characterized by high input and high environmental risk. To investigate the effects of summer catch crop (sweet corn, common bean, garland chrysanthemum and edible amaranth), residue management, and soil temperature and water on the succeeding cucumber rhizosphere nitrogen mineralization in intensive production systems, we determined the rates of net nitrogen mineralization and nitrification in a 4-year field experiment on greenhouse cucumber double-cropping systems. Summer catch crop and its residue significantly increased the succeeding cucumber rhizosphere mineral nitrogen contents, when compared to conventional practices. In general, summer catch crop and its residue significantly increased the rates of both net nitrogen mineralization and net nitrogen nitrification at 4 or 40A degrees C, and increased the rates of net nitrogen immobilization (negative mineralization) and net nitrogen nitrification at 15 or 28A degrees C, in succeeding cucumber rhizosphere after four-year treatment. Soil temperature and water had more influence than catch crops and residue management on N mineralization. The effect of carbon on nitrogen mineralization was more pronounced than that of nitrogen, and the effect of microbial carbon on the different forms of inorganic N was more pronounced than that of organic carbon. When the effects of soil temperature and water content were eliminated, cumulative net nitrogen mineralization and nitrification in catch crop and residue management plots were 296-784 and 57-84% higher, respectively, than conventional practices plots. Catch crops and residue management influenced change of ammonium-N more significantly than that of nitrate-N. Additionally, there were complex relationships between fruit yield and soil N mineralization in catch crop- and residue management-induced systems.