Abstract:
Management practice is an important factor for soil quality changes. Changes in SOC (soil organic C),TSN (total soil nitrogen),Total P, Olsen P and NO3--N were investigated in topsoil 0-20 cm and 0-200 cm of 5-year, 10-year, and 15-year orchard of Wangdonggou watershed in Gully Region of Loess Plateau. SOC and TSN content of topsoil in orchard changed little with planting year; however, total P and Olsen P contents significantly increased. For the orchard in the tableland, SOC is 7.5, 6.7, and 6.7 g/kg in 5-year, 10-year, and 15-year orchard, respectively, TSN is 0.94, 0.85, and 0.83 g/kg, respectively. For 15-year orchard in the tableland, total P and Olsen P increased by 11% and 60%, respectively, compared with 5-year orchard. For the orchard in the slopeland, SOC is 6.3, 6.2, and 6.5 g/kg in 10-year, 15-year, and 20-year orchard, respectively, TSN is 0.76, 0.76, and 0.81 g/kg, respectively. For 15-year orchard in the tableland, total P and Olsen P increased by 20% and 28%, respectively, compared with 10-year orchard. SOC, TSN, total P, and Olsen P in the 0-80cm soil profile decreased with depth, but SOC or total P or Olsen P content below 80cm were not significantly different. In addition, nitrate accumulation in 0-100 and 150-300cm increased significantly with planting year.