基于几何方法评价长期施用化肥坡耕地作物轮作系统可持续性

Evaluation of crop rotation system sustainability in slope land under long-term chemical fertilization based on geometry method

为了评价长期施用化肥条件下黄土丘陵区坡耕地作物轮作系统的可持续性,本文基于三角形面积法,采样测定了长期施肥试验小区(17年)的土壤理化属性及作物产量,将所测定的18项指标划分并转化为土壤物理指数、养分指数和作物指数,并计算出可持续性指数(三角形面积)。结果表明,1)与对照(N0P0)相比,长期施用化肥可以提高系统的可持续性,物理指数、养分指数、作物指数及可持续性指数平均增加16.0%、15.8%、64.1%和76.9%;2)单施氮、磷处理,可持续性指数随着施肥量的增加(N0P0→N1P0\N0P1→N2P0\N0P2)而增加,分别较对照(0.66)增加了13.6%、68.2%和68.3%、81.8%,但低于临界值(1.3)42.3%、14.6%和14.6%、7.7%,说明单施化肥处理的坡耕地作物轮作系统不可持续;3)氮磷配施可持续性指数平均比临界值(1.3)高39.2%,坡耕地作物轮作系统具有较好的可持续性。系统可持续顺序依次为N1P2(2.15)>N2P1(1.88)>N2P2(1.62)>N1P1(1.57)。处理N1P2(施N 55.2 kg/hm2,P2O590 kg/hm2)是该研究区坡耕地可持续作物轮作系统的最优化肥施用配比。

To evaluate the sustainability of crop rotation system in the cultivated slope land under 17-year continuous chemical fertilization condition in the Loess Hilly Region,in the present study,based on the method of area of triangle,18 indicators（both soil and crop components） were selected,determined and classified as well as transformed into the three kinds of indexes including the soil physical index,the soil nutrient index and the ground-above crop index.Then,the sustainability index（namely area of triangle） was calculated to assess the status of the crop rotation system with the three indexes according to the triangle method.The results indicated that,there existed an improvement in the system sustainability with the fertilization treatment as compared to the control of N0P0,which did not receive any fertilizer.The determined indexes were all increased in various degrees with the physical index of 16.0%,nutrient index of 15.8%,crop index of 64.1% and the sustainability index of 76.9%.Along with the increment of single fertilization input（N0P0→N1P0／N0P1→N2P0／N0P2）,the sustainability index increased by 13.6%,68.2% and 68.3%,81.8%,respectively in comparison with the control of N0P0,while far less than the threshold of 1.3（42.3%,14.6% and 14.6%,7.7%,respectively）.Thus,the treatment of single-chemical fertilization was not sustainable in the studied site.However,the treatments of combined with nitrogen and phosphor held a preferable sustainability,in which the sustainability index was averagely 39.2% more than the critical value（1.3）.The rank of the crop rotation system sustainability was N1P2（2.15） 〉 N2P1（1.88） 〉 N2P2（1.62） 〉 N1P1（1.57）.Therefore,the N1P2（N 55.2 kg/ha,P2O5 90 kg/ha） was the optimal chemical fertilizer-applied treatment in the research area.