Nelson Nathan O, Parsons John E, Mikkelsen Robert L
USDA-ARS Northwest Irrigation and Soils Research Laboratory, Kimberly, ID 83341-5076, USA.
J Environ Qual. 2005 Oct 12;34(6):2024-35. doi: 10.2134/jeq2004.0445. Print 2005 Nov-Dec.
Accurate descriptions of P leaching are important because excess P applied to soils can enter surface water via leaching and subsurface transport, thereby negatively impacting water quality. The objectives of this study were to monitor P leaching in soils with a long-term history of waste application, relate soil solution P concentrations to soil P status, and quantify P leaching losses. Soil solution was monitored for 20 mo with samplers installed at 45-, 90-, and 135-cm depths in two pits (1 x 3 x 1.5 m) in Autryville (loamy, siliceous, thermic Arenic Paleudults) and Blanton (loamy, siliceous, semiactive, thermic Grossarenic Paleudults) soils located in a grazed pasture in Sampson County, NC, which had received swine waste for >20 yr. Maximum soil solution P concentrations at 45 cm exceeded 18 mg L(-1) in both soils. Soil solution P concentrations at 90 cm in the Blanton soil were similar to that at 45 cm indicating low P sorption. Soil solution P concentrations at 90 cm in the Autryville soil averaged 0.05 mg L(-1) compared to 10 mg L(-1) at 45 cm. A split-line model related soil solution P concentration to the degree of phosphorus saturation (DPS), identifying a change point at 45% DPS. Phosphorus movement past 45 cm equaled or exceeded surplus P additions for both soils. Long-term waste applications resulted in DPS > 90%, high soil solution P concentrations, and substantial vertical P movement. Phosphorus leaching should be considered when assessing long-term risk of P loss from waste-amended soils.
准确描述磷淋失很重要，因为施用于土壤的过量磷可通过淋溶和地下运输进入地表水，从而对水质产生负面影响。本研究的目的是监测长期施用废弃物土壤中的磷淋失情况，将土壤溶液中的磷浓度与土壤磷状况相关联，并量化磷淋失损失。在北卡罗来纳州桑普森县一个放牧牧场的奥特里维尔（壤质、硅质、热性砂质古老成土）和布兰顿（壤质、硅质、半活性、热性粗砂质古老成土）土壤的两个坑（1×3×1.5米）中，在45厘米、90厘米和135厘米深度安装采样器，对土壤溶液进行了20个月的监测，这些土壤已经接受猪粪超过20年。在这两种土壤中，45厘米深处的土壤溶液最大磷浓度均超过18毫克/升。布兰顿土壤90厘米深处的土壤溶液磷浓度与45厘米处相似，表明磷吸附较低。奥特里维尔土壤90厘米深处的土壤溶液磷浓度平均为0.05毫克/升，而45厘米处为10毫克/升。一个分段模型将土壤溶液磷浓度与磷饱和度（DPS）程度相关联，确定在45%DPS处有一个变化点。两种土壤中超过45厘米的磷移动量等于或超过了多余磷的添加量。长期施用废弃物导致DPS>90%、土壤溶液磷浓度高以及大量的垂直磷移动。在评估废弃物改良土壤中磷损失的长期风险时，应考虑磷淋失。
