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本文以黄土高原生态系统中土壤氮库为中心,研究了土壤氮库的能量、流量以及消长趋势。研究结果表明,黄土高原表层(0—20cm)土壤氮库储氮量为1.5×10~8t,主要吸肥层(0—1m)为5.0×10~8t。高产农田土壤氮库储量为2—3t/ha,中产农田土壤为1.5—2.0t/ha,低产农田土壤仅1.0—1.5t/ha。黄土高原土壤氮库的流入量为235×10~4t,其中化学氮肥流入量占总流入量57.0％,有机肥占36.6％;流出量为250×10~4t,其中由作物收获流出氮量占69.6％,水土流失占12.8％,土壤氮库呈现负平衡,其中氮储量有缓慢下降趋势。为此,要大力增加化学氮肥与有机肥投入量。同时应采取多种措施,以提高有机氮流入量,还应大力降低非生产性氮流出量,使土壤氮库保持动态平衡与稳步增长。
In this paper, the soil nitrogen pool in the Loess Plateau ecosystem as the center, the study of soil nitrogen pool energy, flow and the trend of decline. The results showed that the nitrogen storage in the surface layer (0-20cm) of the Loess Plateau was 1.5 × 10 ~ 8t and that of the main absorption bed (0-1m) was 5.0 × 10 ~ 8t. Soil nitrogen reserves of high yielding farmland are 2-3t / ha, middle farmland soil is 1.5-2.0t / ha, low yield farmland soil is only 1.0-1.5t / ha. The influx of soil nitrogen in the Loess Plateau was 235 × 10 ~ 4t, of which chemical nitrogen inflow accounted for 57.0% of the total inflow and organic fertilizer accounted for 36.6%; outflow was 250 × 10 ~ 4t, of which crop nitrogen 69.6%, soil erosion accounted for 12.8%, soil nitrogen pool showed a negative balance, of which nitrogen reserves showed a slow decline. To this end, we must vigorously increase the chemical nitrogen and organic fertilizer inputs. At the same time, a variety of measures should be taken to increase the inflow of organic nitrogen, and the non-productive nitrogen outflow should be greatly reduced so that the soil nitrogen pool will maintain a dynamic equilibrium and a steady growth.