基于养分丰缺诊断和主成分分析相结合的桑园土壤肥力评价

摘要

Soil fertility is synthetically expressed by various soil factors and can greatly affect the yield and quality of crops.Identifying soil fertility and the limiting factors are the basis of fertilizer application in mulberry orchard.In this study,14 soil fertility indexes were analyzed from 50 soil samples from 25 mulberry orchards in Hai'an County of Jiangsu Province,and then soil fertility was assessed by using the combining method of soil fertility grade and main component analysis.The results showed that soil fertility was high generally in the investigated orchards and the fertility of top layer (0-20 cm) was higher than that of lower (20-40 cm).However,considerable differences in soil fertility existed among different orchards,organic matter,nitrogen and potassium were partially deficient,phosphorus,magnesium,manganese and zinc were deficient only in several orchards,but iron and copper were higher in all orchards.Four main components were isolated and they reflected about 85％ of all soil information of orchard,and the first main component was integrative nutrient factor,contributing to 44.41％; the second main component was pH factor,contributing to 24.03％; the third and fourth main component were related to the negative and positive function of zinc,contributing to 8.92％ and 7.52％,respectively.Furthermore,the total 25 orchards were classified into four varieties representing different fertility conditions.These results suggested that the method of soil nutrient grades was detailed but the method of main component analysis was integrative,they were complementary and their combination could better assess soil fertility of mulberry orchard.%如何客观地评价桑园土壤肥力和诊断其限制因子是桑园合理施肥的依据.本研究以海安县为研究区域,以田块尺度为评价单元,采集25个代表性桑园的表层(0 ～ 20 cm)和亚表层(20 ～ 40 cm)土样,并分析14个土壤肥力指标,运用养分丰缺诊断和主成分分析相结合的方法,对该区域桑园土壤肥力进行了评价.养分丰缺诊断结果表明:调查点桑园土壤肥力整体较高,表层土壤肥力高于亚表层,但不同桑园之间肥力变异很大,部分桑园有机质、氮、钾较为缺乏,个别桑园磷、镁、锰、锌、钙出现缺乏.采用主成分分析的方法,将14个土壤肥力指标提取为4个主成分,可反映桑园土壤全部信息的84.88％.第1主成分为养分综合因子,贡献率为44.41％;第2主成分为pH因子,贡献率为24.03％;第3主成分和第4主成分主要反映了锌的正负效应,贡献率分别为8.92％和7.52％.将25个桑园聚为4类,每一类代表不同的土壤肥力状况.基于养分丰缺诊断和主成分分析相结合的方法,可较为全面评价桑园土壤肥力状况.