不同种植模式和坡度对片麻岩山坡地氮素流失的影响

通过室外人工模拟降雨的方法,研究了在不同坡度(5°,15°,25°,35°)与不同欧李种植模式(1,2,3行)下对片麻岩山坡地土壤坡面氮素流失和产流的影响。结果表明:(1)产流时间随着坡度增大而提前,平均产流时间从种植模式3行到1行推迟了59.23%,2行到1行推迟了32.28%;不同种植模式下产流强度及波动幅度均为1行>2行>3行;(2)降雨过程中,不同种植模式下氮素流失量和流失浓度表现为1行>2行>3行,不同坡度下,氮素流失量和流失浓度为5°<15°<25°>35°,临界坡度为25°;(3)相同坡度,种植模式由2行到3行时硝态氮流失量减幅最大,5°,15°,25°,35°分别减少了16.78%,44.71%,41.33%,41.89%;(4)氮素流失过程中硝态氮流失量占比40.35%,铵态氮流失量占比10.13%,流失形式以硝态氮为主;(5)相同种植模式,2种氮素流失量和流失浓度与坡度存在二次函数关系,相同坡度,与种植模式存在线性关系,相关系数(R^2)范围分别为0.531~0.999,0.102~0.999;(6)种植模式与硝态氮流失量和铵态氮流失量均呈线性负相关关系,是影响氮素流失的主要因子。在片麻岩山坡地,利用多行交错方式种植欧李可显著降低氮素流失。

Effects of Different Vegetation Patterns and Slopes on Nitrogen Loss in Gneiss Hillside

Through the method of outdoor artificial rainfall simulation, the effects of different slopes (5°, 15°, 25° and 35°) and different planting patterns of Prunus humilis (one row, two rows and three rows) on nitrogen loss and runoff production in gneiss hillsides were studied. The results showed that:(1) The runoff yield time was advanced with the increasing of the slope gradient, and the average runoff yield time was delayed by 59.23% from three rows planting to one row planting, and it was delayed by 32.28% from two rows planting to one row plant, and the runoff yield intensity and fluctuation range of the different planting patterns followed the order of one row > two rows > three rows. (2) During the rainfall process, the nitrogen loss and the loss concentration of different planting patterns were sequenced as one row > two rows > three rows. Under the different slopes, the nitrogen loss and the loss concentration were sequenced as 5° < 15° < 25° > 35°, and the critical slope gradient was 25°. (3) On the same slope, the loss of nitrate nitrogen was the largest when the planting pattern was two rows to three rows, which decreased by 16.78%, 44.71%, 41.33% and 41.89%, respectively. (4) During the nitrogen loss process, nitrate nitrogen loss accounted for 40.35%, ammonium nitrogen loss accounted for 10.13%, and nitrate nitrogen was the main form of loss. (5) In the same planting pattern, there was a quadratic function between the loss amount and the loss concentration of the nitrogen and the slope, the correlation coefficients (R²) ranged from 0.531 to 0.999. On the same slope, the loss amount and the loss concentration of the nitrogen had linear relationship with the planting pattern, and the correlation coefficients (R²) ranged from 0.102 to 0.999. (6) Planting pattern was negatively correlated with nitrate nitrogen loss and ammonium nitrogen loss, which was the main factor affecting nitrogen loss. In the gneiss hillsides, planting P. humilis in multi-row staggered way could significantly reduce nitrogen loss.