吉林省春玉米种植区土壤磷库特征及磷素淋失风险评价

Characteristics of soil phosphorus pool and risk assessment of phosphorus leaching in spring maize planting area of Jilin

【目的】探明春玉米主产区主要土壤类型的磷库特征,合理评估该区域土壤磷素淋失风险,为减少磷投入、实现土壤磷养分的高效利用及减小养分流失所导致的环境风险提供参考。【方法】于2018年在吉林省春玉米种植区,采集4种主要土壤类型(黑土、黑钙土、白浆土、暗棕壤)表层土(0~20 cm),测定全磷、速效磷(Olsen-P)和水溶性磷(CaCl2-P)含量,分析土壤CaCl2-P与Olsen-P含量的关系,确定4种土壤类型磷素淋失的临界值。【结果】黑土、黑钙土、白浆土和暗棕壤全磷含量平均值依次为0.48,0.51,0.55和0.79 g/kg,Olsen-P含量平均值依次为73.34,35.85,39.52和37.02 mg/kg。与第二次土壤普查结果相比,4种土壤类型的全磷含量均有所增加。根据《中国土壤》中土壤Olsen-P含量分级标准,可知大部分土壤的Olsen-P含量都处于极好水平(>40 mg/kg)。土壤CaCl2-P和Olsen-P含量之间的关系符合双直线模型。黑土、黑钙土、白浆土和暗棕壤磷素淋失“突变点”所对应的Olsen-P含量分别为78.82,47.37,48.61和54.00 mg/kg,CaCl2-P含量为0.94,0.54,0.53和0.75 mg/kg。【结论】随着耕种时间的延长,春玉米种植区土壤全磷含量不断增加,其中Olsen-P含量增加更为明显。当土壤Olsen-P含量大于磷素淋失临界值时,41.4%的黑土、33.3%的黑钙土、30.4%的白浆土和22.7%的暗棕壤均存在磷素淋失风险。

【Objective】This study explored the characteristics of phosphorus pool of main soil types in the main spring maize producing areas and assessed the risk of soil phosphorus leaching to provide reference for reducing phosphorus input,achieving efficient use of soil phosphorus nutrients,and reducing environmental risks caused by nutrient loss.【Method】In 2018,the surface soil(0-20 cm)of four main soil types(black soil,chernozems,albic soil and dark brown forest soil)was collected in the spring maize planting area of Jilin to determine the contents of total phosphorus,available phosphorus(Olsen-P)and water-soluble phosphorus(CaCl2-P).The relationship between soil CaCl2-P and Olsen-P content was analyzed and the critical value of phosphorus leaching was determined.【Result】The average values of total phosphorus in black soil,chernozems,albic soil and dark brown soil were 0.48,0.51,0.55 and 0.79 g/kg,and the average values of Olsen-P were 73.34,35.85,39.52 and 37.02 mg/kg,respectively.Compared with the second soil survey,the total phosphorus content of the four soil types increased continuously.According to the grading standard of soil Olsen-P content in“China Soil”,the Olsen-P content of most soils was at the excellent level(>40 mg/kg).The relationship between CaCl2-P and Olsen-P was fitted well with line-line model.The Olsen-P contents corresponding to the change-point of phosphorus leaching in black soil,chernozems,albic soil,and dark brown forest soil were 78.82,47.37,48.61 and 54.00 mg/kg with corresponding CaCl2-P contents of 0.94,0.54,0.53 and 0.75 mg/kg,respectively.【Conclusion】The content of soil total phosphorus was increasing,and the increase of Olsen-P content was more significant.When the soil Olsen-P content is higher than the critical value of phosphorus leaching,41.4%black soil,33.3%chernozems,30.4%albic soil and 22.7%dark brown forest soil have the risk of phosphorus leaching.