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首先,侵蚀损害生产力最主要的是减低有效种植土壤层含水量。土壤含水量偏低使作物吸收水分需要更频繁、更强大的吸力作用。根系层持水性能变化或根系层深度减小,可使有效种植土壤含水量降低。倘底土对根系层有毒害或太硬或通气不良都妨碍根系生长,故侵蚀将降低根系层深度。由于表土的有效种植层含水量常常高子底土,当表土流失时,根系层的持水性能总是会变化的。其次,由于供给植物养分减少,侵蚀也使生产力降低。被侵蚀土壤的颗粒从农田带走被作物吸收的养分,流入河川湖泊。由于底土涵蓄的种植养料一般较表土为少,需要增加肥料以保持作物产量。虽然肥料能部份地使裸露的底土上作物的低产量增加,但需增加生产投资。倘底土的粘土成份比表土多
First of all, the most important factor that erodes productivity is to reduce the amount of water effectively planted in the soil layer. Low soil moisture levels allow crops to absorb moisture more often and with more powerful suction. Changes in water holding capacity of the root system or the depth of the root system to reduce the effective planting soil moisture can be reduced. If subsoil poisoning or too hard on the root layer or poor ventilation are hindered root growth, so erosion will reduce root depth. As the effective topsoil moisture content of growing sub-subsoil often high, when the loss of topsoil, the water-holding capacity of the root layer will always change. Second, erosion reduces productivity as a result of reduced supply of plant nutrients. Eroded soil particles take away nutrients that are absorbed by crops from farmlands and into rivers and lakes. Since subsoil implants tend to have less nutrients than topsoil, more fertilizer is needed to maintain crop yields. While fertilizers can in part increase the low yields of bare subsoil crops, increased production investment is required. If the subsoil clay content than the topsoil