中国西北旱区砂田表层土壤养分效应对连作响应的整合分析OA北大核心CHSSCDCSTPCD

The prolonged tillage,unreasonable irrigation and wind erosion bring crisis and uncertainty to the soil quality and land productivity of gravel-sand mulched field in the arid and semi-arid areas of Northwest China.However,the comprehensive impact of continuous cropping on topsoil nutrients in gravel-sand mulched field is currently unclear.In this study,we collected 586 pieces of data from 16 papers published in international and domestic journals.After that,the differences in soil water content(SWC),soil nutrient properties(SOM,TN,TP,TK,AN,AP,AK,TSS,representing soil organic matter,total nitrogen,total phosphorus,total potassium,alkaline nitrogen,available phosphorus,available potassium and total soluble salt,respectively),and soil pH between gravel-sand mulched field with different continuous cropping years(4-6,7-9,10-12,13-15,and 16-20)and farmland mulched with gravel for 1-3 years(CK)were quantitatively analyzed based on Meta-analysis.Furthermore,the response characteristics,occurrence path and driving factors of topsoil nutrient properties to continuous cropping years and water-salt environment were systematically clarified,and the soil fertility level of all treatments was comprehensively evaluated using principal component analysis,aiming to further deeply reveal the soil nutrient degradation mechanism of continuous cropping gravel-sand mulched field.The results showed that the topsoil moisture and nutrients of gravel-sand mulched field presented an overall downward trend with increasing years of continuous cropping(P＜0.05).Compared to CK,the contents of SWC,SOM,TN,TP,TK,AN,AP,and AK of 4-20 years decreased by 39.06％,14.21％,14.96％,10.06％,8.20％,15.87％,37.01％,and 18.60％,respectively(P＜0.05).It was worth noting that the contents of SOM,TN,TP,TK,AN,AP,AK began to significantly decline from 10 to 12 years(P＜0.05).However,the relative changes in soil SOM,TP,TK,and AK contents of 4-6 years were not significant(P＞0.05).Gravel-sand mulched field had a significant salt pressure effect within 12 years of cultivation(P＜0.05).After that,the topsoil TSS content began to show an increasing trend(P＜0.05),and soil pH increased by 1.29％overall(P＜0.05).The continuous cropping years were key factor for the variation of TN,TP and AK,and SWC was the dominant factor in the succession of SOM,AP and TSS in gravel-sand mulched field.In conclusion,gravel-sand mulched field would experience significant topsoil nutrient deficiencies after about 10 years of continuous cropping.Therefore,it is urgent to propose scientific and reasonable farmland management measures to effectively improve the soil fertility of degraded gravel-sand mulched field.