Temporal-spatial variations of ammonia and nitrate under application of inorganic and organic fertilizers in purple soil of winter wheat

The temporal-spatial variations of ammonia and nitrate were studied under application of inorganic and organic fertilizers in purple soil of winter wheat. The results show that there are two obvious reduction-and-increase turns for soil ammonia and nitrate during different growth periods of winter wheat, which are 15 days and 120 days after fertilizers application. The former (15th day) is believed to be related to nitrification and volatilization. The latter (120th day) is affected by both the strong absorption of plant and mineralization release. The trends of ammonia and nitrate in purple soil at different soil profiles (0～15cm, 15～30cm, 30～50cm) are affected by organic manure, which means that the nitrate is retained to move slowly to some degree. The nitrate-retaining effect of each treatment behaves as straw＋fertilizer＞pig manure＋fertilizer＞chicken manure＋fertilizer＞pure fertilizer. There is significantly negative correlation between the quantity of ammonia and nitrate, and the pure fertilizer treatment is the most significant.