不同绿肥覆盖对紫色土坡地柑橘园土壤侵蚀及有机碳流失的差异性影响OA

[Objective]This study investigates the effectiveness of green manure cover crops in controlling runoff,soil erosion,and the loss of soil organic carbon(SOC)and dissolved organic carbon(DOC)in citrus orchards on purple soil slopes.[Methods]Based on a long-term fixed-point monitoring experiment in a purple soil citrus orchard,this study conducted a comparative analysis of runoff amount,soil erosion amount,SOC and DOC loss amounts under four management practices:ryegrass cover(Lolium perenne L.),hairy vetch cover(Vicia villosa Roth.),clover cover(Trifolium repens L.),and the farmer's conventional clean tillage.[Results]All treatments reduced runoff,soil erosion,and SOC and DOC loss to varying degrees,with the overall performance being ryegrass>clover>hairy vetch>clean tillage.Compared to clean tillage,ryegrass reduced surface runoff by 22.75%,interflow by 41.21%,soil erosion by 60.37%,SOC loss by 29.29%,and DOC loss by 23.34%.Clover reduced surface runoff by 21.06%,interflow by 33.72%,soil erosion by 41.87%,SOC loss by 34.80%,and DOC loss by 24.63%.Hairy vetch had a weaker effect on soil and water conservation,reducing surface runoff by 10.56%,interflow by 30.02%,soil erosion by 53.12%,SOC loss by 25.85%,and DOC loss by 4.59%.During the experiment,the processes of soil erosion and organic carbon loss were highly synchronized with rainfall patterns.From December to the following January,rainfall was scarce,and the erosion amount was generally below 15.00 kg/hm2.In March,with the increase in rainfall,the erosion amount increased to 11.11-24.72 kg/hm2,while SOC loss was less than 0.60 kg/hm2.The rainy season from April to September was the main erosion period.In June,the erosion amount under clean tillage reached a peak of 221.26 kg/hm2.Although rainfall dropped sharply in July and August,the erosion amount was still higher than 100.00 kg/hm2.Increased rainfall in September led to a significant increase in erosion to 201.66 kg/hm2,and the SOC loss was also higher than 5.00 kg/hm2.Under different rainfall levels,green manure significantly reduced the runoff coefficient and soil erosion modulus of purple soil.Compared to clean tillage,ryegrass reduced the runoff coefficient by 23.38%-43.89%,and the soil erosion modulus by 34.91%-78.81%.Clover decreased the coefficient by 16.75%-42.24%and modulus by 33.31%-61.70%and hairy vetch reduced the coefficient and modulus by 16.90%-32.73%and 35.05%-71.74%,respectively.[Conclusion]At both annual and rainfall event scales,green manure cover crops can effectively suppress soil and water loss and organic carbon loss in purple soil slopes.Among them,ryegrass has the best soil and water conservation effect,followed by clover and hairy vetch.However,clover has the best organic carbon sequestration effect,followed by ryegrass and hairy vetch.Therefore,selecting green manure species with corresponding capabilities according to different management objectives is an important measure to prevent and control soil and water loss and organic carbon loss in purple soil slopes.