Elliott H A, Brandt R C, Kleinman P J A, Sharpley A N, Beegle D B
Dep. Agricultural and Biological Engineering, The Pennsylvania State University, University Park, PA 16802, USA.
J Environ Qual. 2006 Oct 27;35(6):2195-201. doi: 10.2134/jeq2006.0014. Print 2006 Nov-Dec.
Phosphorus release to runoff varies widely for different land-applied organic P sources even when spread at equivalent total P rates. To address this variability, some P site indices include tabulated P source coefficients (PSCs) for differential weighting of applied P materials based on their runoff enrichment potential. Because runoff P can vary widely even within source categories depending on composition, storage, and treatment differences, this study explored a method for estimating PSCs based on the water-extractable P (WEP) content of the applied amendment. Using seven published rainfall-runoff studies that followed National Phosphorus Research Project protocols, runoff dissolved P (RDP) was correlated (r(2) = 0.80) with WEP for multiple surface-applied manures and biosolids. Assuming amendments with WEP >/= 10 g kg(-1) behave as highly soluble P sources and have a maximum PSC of 1.0, an empirical equation was developed for computing source-specific PSCs from laboratory-determined WEP values [PSC = 0.102 x WEP(0.99)]. For two independent runoff experiments, correlations between RDP loss and P source loading rate were improved when loading rates were multiplied by the computed (r(2) = 0.73-0.86) versus generic (r(2) = 0.45-0.48) PSCs. Source-specific PSCs should enhance the ability of assessment tools to identify vulnerable sites and P loss management alternatives, although the exact inclusion process depends on index scaling and conceptual framework.
即使以相同的总磷施用量进行撒施，不同土地施用有机磷源向径流中的磷释放量差异也很大。为了解决这种变异性问题，一些磷位点指数包括列表形式的磷源系数（PSC），用于根据施用磷材料的径流富集潜力进行差异加权。由于即使在源类别内，径流磷也可能因组成、储存和处理差异而有很大变化，本研究探索了一种基于施用改良剂的水可提取磷（WEP）含量估算PSC的方法。利用七项遵循国家磷研究项目协议的已发表降雨径流研究，对多种地表施用的粪肥和生物固体，径流溶解磷（RDP）与WEP相关（r² = 0.80）。假设WEP≥10 g kg⁻¹的改良剂表现为高溶解性磷源且最大PSC为1.0，开发了一个经验方程，用于根据实验室测定的WEP值计算特定源的PSC [PSC = 0.102×WEP⁰·⁹⁹]。对于两项独立的径流实验，当负荷率乘以计算出的（r² = 0.73 - 0.86）而非通用的（r² = 0.45 - 0.48）PSC时，RDP损失与磷源负荷率之间的相关性得到改善。特定源的PSC应能增强评估工具识别脆弱地点和磷损失管理替代方案的能力，尽管确切的纳入过程取决于指数缩放和概念框架。
