Nitrogen Loss of Loess Soil as Affected by NH₄NO₃ Applying in Process of Water Erosion

The millets fertilizing NH₄NO₃ with high N(NH₄NO₃ 500 kg/hm²) and low N(NH₄NO₃ 250 kg/hm²), are planted in the slope lands with 10°, 20°, 25°and 30° slope gradient. The research results were as follows: The mean concentrations of NH₄⁺-N, NO₃^--N and NH₄⁺+NO₃^- in runoff were 1.06, 0.76, and 1.82 mg/kg in high N treatment (HNT), and 0.64, 1.29, 1.93 mg/kg in low N treatment (LNT) respectively. The loss amounts of them in runoff were 17.90, 12.93, and 30.84 kg/(km²·a) in HNT, and 11.90, 23.86, 35.77 kg/(km²·a) in LNT seperately. The concentrations of organic matter and total N in sediment were 5.21 and 0.536 g/kg in HLT, 4.94 and 0.481 g/kg in LNT seperately. Accordingly, the loss amounts of them in sediment were 5 702, 5 743 kg/(km²·a) in HLN, and 498,559 kg/(km²·a) in LNT respectively.