坡位与利用方式对红壤磷素储存容量的影响差异——以江西鹰潭孙家小流域为例

Differential effects of slope position and land use on red soil phosphorus storage capacity:a case study of the Sunjia Small Watershed in Yingtan,Jiangxi,China

为明确坡位与利用方式对土壤磷素储存容量(SPSC)的影响差异,以更加准确地评估坡耕地红壤磷的流失风险,本研究以江西鹰潭孙家小流域内不同坡位(坡顶、坡上、坡中、坡底)及不同利用方式(稻田、花生旱地、橘园)的表层土壤为研究对象,对比分析了SPSC的变化规律与差异,探讨了土壤全碳、全氮、全磷、有效磷、铁铝氧化物含量等因子对SPSC的影响。结果表明:不同坡位的稻田、花生旱地与橘园的SPSC变化范围分别为-410.9~-137.8、-283.8~-128.0 mg·kg^(-1)及-280.6~-36.3 mg·kg^(-1);且随坡位的降低,稻田(坡底除外)与橘园SPSC显著降低,而花生旱地SPSC则增加。与稻田土壤相比,同一坡位花生旱地与橘园SPSC相对增加;相关分析表明,不同坡位的稻田、花生旱地及橘园SPSC与土壤非晶质铁铝氧化物、游离态铁铝氧化物极显著正相关,且游离态氧化铝的影响相对最大,而与有效磷、总碳、总氮则显著负相关。江西鹰潭孙家小流域内红壤坡耕地SPSC均为负值,意味着此时的土壤均为磷源,土壤磷均具有流失风险;坡底的稻田及橘园、坡顶花生旱地土壤磷的流失风险相对较高,应及时采取相应的调控措施以有效降低土壤磷素的流失潜能与风险。

In this study,we aimed at providing a detailed analysis of the differential effects of slope position and land use on soil phosphorus storage capacity(SPSC)in red soil,offering a precise P loss risk evaluation in sloping cultivated land.Our study focused on the surface soil of various slope positions(i.e.,hilltop,upslope,mid-slope,and downslope)and diverse land use types(i.e.,paddy fields,peanut uplands,and citrus orchards)in the Sunjia Small Watershed in Yingtan,Jiangxi.We compared and analyzed the variations and differences in SPSC,investigating how various factors,such as total carbon(TC),total nitrogen(TN),total P(TP),available P,and ironaluminum oxide content,could affect SPSC.Our results revealed SPSC ranges for paddy fields,peanut uplands,and citrus orchards soils as follows:-410.9 to -137.8 mg·kg^(-1),-283.8 to -128.0 mg·kg^(-1),and-280.6 to -36.3 mg·kg^(-1),respectively.With slope position reduction,SPSC significantly decreased in paddy fields(except for the positions at the bottom of the slope)and citrus orchard soils,while it increased in peanut uplands.Compared to paddy field soil,the peanut upland and citrus orchard SPSCs were relatively higher at the same slope position.Our correlation analysis revealed a significant positive correlation between the SPSCs in different slope positions of paddy fields,peanut upland,and citrus orchards with soil iron-aluminum oxides and with free iron-aluminum oxide influence being relatively the largest.Moreover,we also observed a significant negative correlation between available P,TC,and TN.The paddy field,peanut upland,and citrus orchard SPSCs were negative at different slope positions in the Sunjia watershed of Yingtan,indicating that the soil represents a P source and displays P loss risk.Moreover,paddy fields and citrus orchards at the bottom of the slope and peanut uplands at the hilltop display a relatively higher P loss risk,requiring timely and appropriate control measures to effectively reduce the potential and soil P loss risk,requiring timely and appropriate control measures to effectively reduce the potential and soil P loss risk.