Relationship between Row Spacing,Irrigation Rate and Growth Redundancy in Alfalfa Population Effects of nitrogen application and irrigation on soil nitrate accumulation, nitrogen balance and use efficiency in summer maize Effect of water and nitrogen coupling on soil nitrate movement and nitrogen uptake of muskmelon Effects of nitrogen application and irrigation on grain yield, water and nitrogen utilizations of summer maize Activities of Enzymes Related to Nitrogenous Metabolism and Grain Quality in Wheat with Different Irrigation Stage and Rate