Effects of Phosphorus Fertilizer Application Rates on Colloidal Phosphorus Leaching in Purple Soil in Southwest China

Abstract

Phosphorus (P) lost via leaching from agricultural land is of major concern for water resource managers worldwide, and colloidal phosphorus (CP) may have a high contribution, since it is an important mobile form of P in soil and subsurface drainage. The objective of this study is to relate P fertilization application rates to CP leaching. To eliminate the influence of climate and facilitate the accurate measurement of P contents in different soil layers, we established soil columns to investigate the impacts of fertilizer application rates and timing on P leaching. Therefore, a soil column leaching experiment was undertaken with different P fertilization application rates (0, 20, 40, 100, 200, and 400 mg kg−1) for purple soil in southwest China. P application rates had significant effects on CP and dissolved phosphorus concentrations in the top soils (p < 0.05) (e.g., 0–10 cm in this study), and they further increased P leaching loss by 24–375%. CP was the dominant P form and contributed 31–61% to total phosphorus in the leachate. The concentration of different P forms in leachates decreased significantly over time, and the risk of P leaching loss was greater within two weeks after P application (p < 0.05). The advisable range of P application rate is recommended to be 0–450 kg ha−1 for agricultural practice, and it is also recommended to keep P fertilizer in the soil for more than two weeks. Some countermeasures, related to application rates and timing, should be taken to minimize the buildup of P in the field and reduce the risk of P leaching.

Characteristics of nitrogen and phosphorus contents in soil and water in an agricultural catchment of the three Gorges reservoir area

“…A comparison of the average contents of TN, NO 3 − -N and TP in the 5 slopes of shallow groundwater revealed that the TN and NO 3 − -N concentrations were more significantly affected by the land utilization mode of the infiltration slopes, but their effect on the TP concentration was not obvious. This is mainly due to the reaction of phosphorus with the soil to form soil minerals, coupled with the adsorption and fixation of phosphorus in different soil layers, which limits its ability to migrate downwards in the soil (Zhang T et al, 2015;He et al, 2022). However, owing to the negative charge of the soil particles, the nitrogen fertilizer applied to the soil had a strong adsorption capacity for ammonium ions and a weak adsorption capacity for nitrate ions (Cai et al, 2016); additionally, the nitrogen Comparison of the average nitrogen and phosphorus contents and dispersion coefficients of shallow groundwater on different slopes.…”