A Tool (SPOLERC) to Guide the Evaluation of Phosphorus Leaching for Agricultural Soil by Using Soil Phosphorus Leaching Change Point in the Lake Xingkai Basin, China

Abstract

BackgroundAs the key factor of soil P leaching risk assessment, soil P leaching change point (CP) has been widely reported. However, there was no report have clearly described the calculation method of soil P leaching CP value and its automation calculation. Additionally, there was no effective risk grading method performed on the classification of soil P leaching evaluation.ResultsThis study has optimized the calculation process of soil P leaching CP value under two different models. Subsequently, based on the Python programming language, a computation tool named SPOLERC (Soil Phosphorus Leaching Risk Calculator) was developed for soil P leaching risk assessment. SPOLERC not only embedded the calculation process of soil P leaching CP value, but also introduced the single factor index (SFI) method to grade the soil P leaching risk level. Considering the relationships between soil Olsen-P and leachable P fitted by using SPOLERC in paddy land soils and arid agricultural land soils in the Lake Xingkai basin, results have shown that there is a good linear fitting relationship between soil Olsen-P and leachable P; and the CP values were 59.63 and 35.35 mg Olsen-P kg-1 in paddy land soils and arid agricultural land soils, respectively. Additionally, 32.7%, 21.8%, and 3.64% of arid agricultural soil samples are at low risk, medium risk, and high risk of P leaching, and 40.6% of paddy land soil samples are at low risk. ConclusionsThe SPOLERC can accurately fit the split-line model relationship between soil Olsen-P and leachable P, and greatly improve the calculating efficiency for soil P leaching CP value. Additionally, the obtained CP value can be used for soil P leaching risk assessment, which can provide support for the quantitative study of soil P leaching loss and the control technology of soil P leaching loss.