Using a Simple Soil Column Method to Evaluate Soil Phosphorus Leaching Risk

• Published in: Clean : soil, air, water air, water, 2013-11, Vol.41 (11), p.1100-1107
• Main Authors: Li, Yuyuan, Gao, Ru, Yang, Rui, Wei, Hongan, Li, Yong, Xiao, Heai, Wu, Jinshui
• Format: Article
• Language: English
• Subjects: Calcareous fluvisol; Change-point method; Leaching; P accumulation; P leaching intensity; Soil testing
• ISSN: 1863-0650; 1863-0669
• DOI: 10.1002/clen.201200372

The impacts of soil P leaching on water eutrophication have widely been concerned. However, there is no dependable method to quantitatively estimate the P leaching risk of soils. In this study, a simple soil column method was developed using two calcareous Fluvisols, silt loam and loam. The soil column was 20 cm in length and 5 cm in diameter, and distilled water was continuously supplied from the top. The volume and dissolved reactive P (DRP) concentrations of leachate were measured. Results showed that DRP concentrations in leachate increased slowly for the low soil Olsen‐P levels but rapidly for the high Olsen‐P levels. According to these two‐phase changes in the DRP versus soil Olsen‐P contents, the thresholds of P leaching risk were estimated to be 41.1 and 62.3 mg P kg−1 (Olsen‐P) for silt loam and loam, respectively. The P leaching intensity of soils increased by 3‐ to 540‐fold if the soil Olsen‐P contents accumulated from 6.6 to 155.5 mg P kg−1. The outcomes derived from this study regarding the determination of P leaching threshold and intensity by the soil column method also need a further verification on more soils with a wide range of physical and chemical properties. The soil column experiment primarily revealed that P leaching dynamics are in a similar low–high–low tendency for dissolved reactive P concentrations in leachate, associated with the characteristics of soil P desorption and not with soil Olsen‐P levels.