渭北旱塬侵蚀退化土壤生产力的恢复与评价

土壤侵蚀会降低生产力,威胁农业生产,因此,对土壤生产力进行恢复和评价具有重要意义。通过人工剥离熟土层,模拟研究不同侵蚀程度下的土壤生产力,选取施肥和覆盖表土2种恢复措施,对其土壤生产力的恢复情况展开研究并进行评价。结果表明:1)土壤侵蚀能够使土壤的理化性状恶化,施肥和覆土均能很好地改善土壤密度和孔隙度等,并能够增加土壤有机质及其他养分的质量分数。2)土壤侵蚀会降低作物产量,在不施肥下,每侵蚀1cm熟土层,玉米产量平均下降1.27%,施肥下每侵蚀1 cm熟土层,玉米产量比对照平均增加0.87%;而每覆盖1cm熟土层,玉米产量平均增加0.91%,但并不能完全补偿侵蚀造成的产量损失。3)利用土壤生产力指数模型(PI模型)计算出了不同措施下的生产力指数,发现:无肥下侵蚀的生产力指数最低,平均每侵蚀1 cm熟土层,生产力指数下降2.17%,施肥下平均每侵蚀1 cm熟土层,生产力指数比无肥增加1.09%,而平均每覆盖1 cm熟土,生产力指数增加1.29%;表明覆土较施肥更易提高土壤生产力。4)对产量和生产力指数进行相关性分析,得出二者具有很好的正相关关系,说明用生产力指数来衡量土壤生产力的高低是可行的。

Soil productivity restoration and evaluation of erosion degradation in Weibei Dry Highland

Soil erosion can decline productivity and threat to agricultural production.Therefore,it is a great significance to restore and evaluate the soil productivity.The recovery of soil productivity was studied and evaluated to simulate different degree of erosion of soil productivity,which selected the fertilization and cover the topsoil two recovery measures through artificial stripping of mellow soil.The results showed that： 1） soil erosion could deteriorate the physical and chemical properties of soil.Fertilization and covering soil could improve the soil bulk density,porosity,and increase soil organic matter and mass nutrient contents.2） Soil erosion could reduce crop yields by an average of 1.27 percent per 1cm mellow soil eroded under no fertilization.Compared with the control treatment,corn yield increased by 0.87% per 1cm mellow soil eroded under fertilization.However,corn yield increased by 0.91% when covered by 1cm mellow soil,but could not completely compensate for the erosion yield losses.3）The value of productivity index under different measures was calculated through soil productivity index model（PI model）.The results showed that the value of productivity index under no fertilization was lowest.The average decrease of productivity index value was 2.17% per 1cm mellow soil eroded under fertilization.The average increase of productivity index value was 1.09% per 1cm cooked soil eroded compared with no fertilization,while the average increase of productivity index value was 1.29% per 1cm mellow soil covered,which indicated that the covering soil was easier than fertilization to improve soil productivity.4） A good positive correlation was found between yield and productivity index by correlation analysis,which indicated that it was feasible to measure soil productivity by productivity index.