Little Joanne L, Nolan Sheilah C, Casson Janna P, Olson Barry M
Alberta Agriculture and Food, Conservation and Development Branch, 206, 7000, 113 St. Edmonton, AB, T6H 5T6, Canada.
J Environ Qual. 2007 Jul 17;36(5):1289-300. doi: 10.2134/jeq2006.0502. Print 2007 Sep-Oct.
Field-scale relationships between soil test phosphorus (STP) and flow-weighted mean concentrations (FWMCs) of dissolved reactive phosphorus (DRP) and total phosphorus (TP) in runoff are essential for modeling phosphorus losses, but are lacking. The objectives of this study were (i) to determine the relationships between soil phosphorus (STP and degree of phosphorus saturation (DPS)) and runoff phosphorus (TP and DRP) from field-sized catchments under spring snowmelt and summer rainfall conditions, and (ii) to determine whether a variety of depths and spatial representations of STP improved the prediction of phosphorus losses. Runoff was monitored from eight field-scale microwatersheds (2 to 248 ha) for 3 yr. Soil test phosphorus was determined for three layers (0 to 2.5 cm, 0 to 5 cm, and 0 to 15 cm) in spring and fall and the DPS was determined for the surface layer. Average STP (0 to 15 cm) ranged from 3 to 512 mg kg(-1), and DPS (0 to 2.5 cm) ranged from 5 to 91%. Seasonal FWMCs ranged from 0.01 to 7.4 mg L(-1) DRP and from 0.1 to 8.0 mg L(-1) TP. Strong linear relationships (r2=0.87 to 0.89) were found between the site mean STP and the FWMCs of DRP and TP. The relationships had similar extraction coefficients, intercepts, and predictive power among all three soil layers. Extraction coefficients (0.013 to 0.014) were similar to those reported for other Alberta studies, but were greater than those reported for rainfall simulation studies. The curvilinear DPS relationship showed similar predictive ability to STP. The field-scale STP relationships derived from natural conditions in this study should provide the basis for modeling phosphorus in Alberta.
土壤有效磷（STP）与径流中溶解态活性磷（DRP）和总磷（TP）的流量加权平均浓度（FWMC）之间的田间尺度关系对于模拟磷流失至关重要，但目前尚缺乏相关研究。本研究的目的是：（i）确定春季融雪和夏季降雨条件下，田间尺度集水区土壤磷（STP和磷饱和度（DPS））与径流磷（TP和DRP）之间的关系；（ii）确定不同深度和空间表示的STP是否能改善对磷流失的预测。对8个田间尺度的小流域（2至248公顷）进行了3年的径流监测。在春季和秋季测定了三层土壤（0至2.5厘米、0至5厘米和0至15厘米）的土壤有效磷，并测定了表层的DPS。平均STP（0至15厘米）范围为3至512毫克/千克，DPS（0至2.5厘米）范围为5至91%。季节性FWMC范围为0.01至7.4毫克/升DRP和0.1至8.0毫克/升TP。发现场地平均STP与DRP和TP的FWMC之间存在强线性关系（r2 = 0.87至0.89）。在所有三层土壤中，这些关系具有相似的提取系数、截距和预测能力。提取系数（0.013至0.014）与艾伯塔省其他研究报告的系数相似，但大于降雨模拟研究报告的系数。曲线DPS关系显示出与STP相似的预测能力。本研究从自然条件得出的田间尺度STP关系应为艾伯塔省磷建模提供基础。
