长期磷肥不均投入下黄土高原土壤磷素有效性及与土壤性质关系分析

Analysis of Phosphorus Availability and Its Relationship with Soil Properties in the Loess Plateau Under Long-term Imbalanced Phosphorus Input

由于科学施肥指导工作和生产实际的脱节,过量施用磷肥的现象普遍存在,进而造成大量磷素在土壤中累积。准确评价土壤中磷素的有效性是土壤磷素科学管理的基础。国际上梯度扩散薄膜技术(DGT)和传统方法相比可以更为准确地反映土壤中元素的生物有效性。以黄土高原具有代表性的60个土壤样品为研究对象,采用传统Olsen法和DGT技术评价多年磷肥投入不均条件下黄土高原地区土壤磷储量及其有效性现状,研究了DGT技术测定的DGT-P与全磷、Olsen-P之间的关系,并利用通径分析探究了土壤磷素有效性和土壤相关理化指标之间的关系。结果表明:黄土高原地区土壤磷素分布不均匀,缺磷与富磷现象并存,富磷土壤主要是耕地样品。磷素活化系数(Olsen-PAC)小于2.0%的土壤样品占76.67%,绝大部分土壤样品磷素有效性低。耕地磷肥投入量过高,活化土壤中的无效磷是黄土高原地区磷素科学管理的主要目标。土壤DGT-P与全磷、Olsen-P呈显著相关性(P<0.01)。黏粒对土壤磷素有效性的直接影响最大,对Olsen-PAC的影响为正效应,对DGT法测定的磷素活化系数(DGT-PAC)的影响为负效应。土壤黏粒含量越高,有效磷库越大,土壤中供植物吸收利用的磷反而越少。

Due to the disconnection between scientific fertilization guidance and the agricultural production,excessive application of phosphorus fertilizer is widespread,which results in the accumulation of large amounts of phosphorus in soil.Accurate evaluation of phosphorus availability in soil is the basis for scientific management of soil phosphorus.Diffusive gradients in thin films technology(DGT)can more accurately reflect the bioavailability of elements in soils than traditional methods.In this study,60 representative soil samples from the Loess Plateau were used to evaluate the status of soil phosphorus pool and its availability in the Loess Plateau under the condition of imbalanced fertilizer input for long period,and traditional Olsen and the DGT methods were used.The relationships between DGT-P,and Total-P and Olsen-P were also studied.Path Coefficient Analysis was used to explore the relationship between soil phosphorus availability and relevant soil physical and chemical indicators.The results showed that the distribution of soil phosphorus was uneven in the Loess Plateau.Phosphorus deficiency and phosphorus enrichment coexisted,specifically,phosphorus rich samples were mainly from farmland.Soil samples with phosphorus activation coefficient(PAC)less than 2.0%accounted for 76.67%of the total samples,and most soil samples had low phosphorus availability.Because phosphorus input in farmland was too high,activating the unavailable phosphorus in soil was the main target of scientific management of phosphorus in the Loess Plateau.Soil DGT-P was significantly correlated with total-P and Olsen-P(P<0.01).Clay content had the greatest direct effect on soil phosphorus availability compared with other factors,and its effect on Olsen-PAC was positive,and the effect on DGT-PAC was negative.The higher the soil clay content,the larger the available phosphorus pool in soil,but the less available phosphorus could be taken up by plants.