长期小麦秸秆还田对壤质潮土磷素含量及磷盈亏的影响

明确长期小麦秸秆还田壤质潮土土壤中磷素演变特征,可为潮土区土壤磷素管理和磷肥高效施用提供理论依据。利用壤质潮土长期定位试验（1992-2015年）,比较单施化肥处理（NP、NPK）和小麦秸秆还田配施化肥处理（NPS、NPKS）土壤有效磷、全磷含量变化,量化土壤磷盈亏和累积磷盈亏,并解析土壤有效磷变化量与累积磷盈亏之间的关系。结果表明,长期施用磷肥和小麦秸秆还田显著提高了土壤有效磷和全磷含量,提升了磷活化系数（PAC）,其年增量分别为0.68~0.78mg/kg、0.0031~0.0047g/kg和0.07%~0.09%,且小麦秸秆还田对土壤有效磷含量的增加速率有抑制作用,对全磷含量的增加有促进作用,但效应不显著。小麦秸秆还田增加土壤磷盈余。在土壤磷盈余时,土壤每盈余100kg/hm²磷,有效磷增加9.7~10.0mg/kg,小麦秸秆还田对其影响不大;在土壤磷亏缺时,土壤每亏缺100kg/hm²磷,秸秆不还田土壤有效磷含量降低12.6mg/kg,小麦秸秆还田土壤降低1.95mg/kg,小麦秸秆还田对土壤有效磷含量的维持有缓冲作用。小麦秸秆配施磷肥是提高和维持壤质潮土土壤磷素水平、增强土壤供磷潜力的重要措施。

Effects of Wheat Long-Term Straw Returning on Soil Phosphorus Content and Phosphorus Balance in Loamy Tidal Soil

Clarifying the evolution characteristics of soil phosphorus in long-term wheat straw return of loamy tidal soil can provide theoretical basis for soil phosphorus management and efficient application of phosphate fertilizer. A long-term experiment in loamy tidal soil (1992-2015) was conducted to compare the changes of soil olsen phosphorus and total phosphorus content in the treatments of chemical fertilizers (NP, NPK) and wheat straw returned (NPS, NPKS) and quantified soil phosphorus balance and accumulated phosphorus balance, and to analyze the relationship between soil olsen phosphorus changes and accumulated phosphorus balance. The results showed that long-term application of phosphorus fertilizer and wheat straw to the field significantly increased soil olsen phosphorus and total phosphorus content, and increased the phosphorus activation coefficient (PAC), with annual increments of 0.68-0.78mg/kg, 0.0031-0.0047g/kg, and 0.07%-0.09%, respectively. Therefore, wheat straw return could inhibit the increase rate of soil olsen phosphorus content and promote the increase of total phosphorus content. But the effect was not significant. Moreover, wheat straw return increased soil phosphorus surplus. When the accumulated phosphorus balance was surplus, the olsen phosphorus content would increase by 9.7-10.0mg/kg with every 100kg/ha of accumulated phosphorus surplus in the soil, and the wheat straw return had few effects on it. When the accumulated phosphorus balance was deficit, the olsen phosphorus content would decrease by 12.6mg/kg under no straw return condition and decrease by 1.95mg/kg under straw return condition with every 100kg/ha of accumulated phosphorus deficit. Therefore, the wheat straw return showed a buffer effect on the effective phosphorus content maintaining. Wheat straw combined with phosphate fertilizer is an important measure to increase and maintain soil phosphorus levels in the loamy tidal soil, and to increase soil phosphorus supply potential.