Liu Jian, Aronsson Helena, Bergström Lars, Sharpley Andrew
Department of Soil and Environment, Swedish University of Agricultural Sciences, Box 7014, 75651 Uppsala, Sweden.
Springerplus. 2012 Dec;1(1):53. doi: 10.1186/2193-1801-1-53. Epub 2012 Nov 28.
Appropriate management of animal waste is essential for guaranteeing good water quality. A laboratory leaching study with intact soil columns was performed to investigate the risk of phosphorus (P) leaching from a clay loam and a loamy sand. The columns (0.2 m deep) were irrigated before and after application of pig slurry on the surface or after incorporation, or application of mineral P, each at a rate of 30 kg P ha(-1). The two soils had different initial P contents (i.e. the ammonium lactate-extractable P was 65 and 142 mg kg(-1) for the clay loam and loamy sand, respectively), but had similar P sorption characteristics (P sorption index 3.0) and degree of P saturation (17-21%). Concentrations of dissolved reactive P (DRP) and total P (TP) before P application were significantly higher in leachate from the loamy sand (TP 0.21 mg L(-1)) than from the clay loam (TP 0.13 mg L(-1)), but only increased significantly after P application to the clay loam. The highest concentrations were found when slurry was surface-applied (DRP 1.77 mg L(-1)), while incorporation decreased the DRP concentration by 64% in the clay loam. Thus moderate slurry application to a sandy soil with low P saturation did not pose a major risk of P leaching. However, application of P increased the risk of P leaching from the clay loam, irrespective of application method and despite low P saturation. The results show the importance of considering soil texture and structure in addition to soil chemical characteristics in risk assessments of P leaching. Structured soils such as the clay loam used in this study are high risk soils and application of P to bare soil during wet periods, e.g. in autumn or spring, should be followed by incorporation or avoided completely.
妥善管理动物粪便对于保证良好水质至关重要。进行了一项使用完整土柱的实验室淋溶研究，以调查黏土和壤质砂土中磷（P）淋溶的风险。在地表施用猪粪浆前后、混入猪粪浆后或施用矿物磷后，以30 kg P ha(-1)的速率对土柱（0.2米深）进行灌溉。两种土壤的初始磷含量不同（即黏土和壤质砂土的乳酸铵可提取磷分别为65和142 mg kg(-1)），但磷吸附特性（磷吸附指数3.0）和磷饱和度（17 - 21%）相似。施用磷之前，壤质砂土渗滤液中溶解态活性磷（DRP）和总磷（TP）的浓度（TP 0.21 mg L(-1)）显著高于黏土（TP 0.13 mg L(-1)），但仅在向黏土施用磷后显著增加。当粪浆进行地表施用时发现最高浓度（DRP 1.77 mg L(-1)），而混入操作使黏土中的DRP浓度降低了64%。因此，向磷饱和度低的砂土适度施用粪浆不会带来磷淋溶的重大风险。然而，施用磷增加了黏土磷淋溶的风险，无论施用方法如何，尽管磷饱和度较低。结果表明，在磷淋溶风险评估中，除了土壤化学特性外，考虑土壤质地和结构也很重要。本研究中使用的黏土等结构性土壤是高风险土壤，在潮湿时期（如秋季或春季）向裸土施用磷后应进行混入操作或完全避免施用。
