摘要
本文进行计算的主要目的在于:①估计耕地中氮淋溶减少措施的效果;②预计瑞典南部总负荷的减少量。采取的主要措施有:①春季谷类作物中种植填闲作物;②在不施粪肥的耕作制度下,减少氮肥的施用量;③春季施用粪肥和少量施用氮肥;④春季种植填闲作物结合施用粪肥并逐渐减少氮肥用量。本文所用的模型是用于描述土壤剖面水、热和氮淋溶的SOIL/SOILN机制模型。氮淋溶过程中的最大减少量是通过种植填闲作物,春季施粪肥与逐渐减少氮肥的施用量相结合而获得的。这种做法使总负荷量减少了16%。但由于春季作物中仅仅30%的面积种植了填闲作物,填闲作物仅将总负荷减少了5%。氮肥减少10%,将导致负荷减少6000t(即减少11%),同时产量减少10%左右。
The aim of the calculations in this paper was i) to estimate the effect of measures to reduce nitrogen leaching from arable land and ii) to estimate what reduction in the gross load from southern Sweden could be expected. The measures taken were i) cultivation of a catch crop in spring cereals; ii) smaller applications of fertilizer-N to crops in cultivation systems without manure; iii) spring application of manure and a smaller amount of complementary fertilizer-N; and iv) a catch crop in combination with spring application of manure and a reduced rate of fertilizer-N. The models used were the mechanistic SOIL/SOILN models describing water, heat, and nitrogen flows in the soil profile. The largest reduction in leaching was obtained with the combination of catch crop, spring application of manure and reduced rate of fertilizer-N. Total gross load decreased with 16% in this scenario. The catch crop scenario reduced gross load by a mere 5% because it was only introduced in 30% of the acreage of spring cereals. The scenario with a 10% reduction in fertilizer-N resulted in a decrease in load of about 6000 tonnes, i.e. 11%, as well as a yield decrease of about 10% Ambio, Vol. 29, No. 2, pp. 67-73, 2000
