Hydrothermal Effects on Phosphorus Bioavailability in Different Soils

Abstract

【Background】 Nutrient cycling and kinetic in soil is mediated by biogeochemical processes which in turn is modulated by soil water and temperature. The aim of this paper is to investigate the hydrothermal effects on bioavailability of phosphorus (P) in different soils. 【Method】 We studied soils with different cultivations using culture experiments: paddy field, upland, vegetable and forest in the same region. There were three moisture treatments for each soil by keeping the soil water content at 40% (W40), 70% (W70) and 100% (W100) of the saturated water content, respectively. For each soil water, there were further three temperature treatments by keeping the soil temperature at 15 ℃ (T15), 25 ℃(T25) and 35 ℃(T35), respectively. All soils were incubated for 15 days, after which we measured the contents of P in different forms. 【Result】 When temperature and soil moisture were the same, the contents of bioavailable P and Olsen-P in different soils were ranked in the order of forest > vegetable > upland > paddy field. When the temperature was the same, soil water content up-regulated HCl-P, Citrate-P, Enzyme-P and Olsen-P, regardless of the soils. When soil moisture content was the same, the temperature positively impacted HCl-P and Olsen-P, negatively affected Citrate-P (p moisture > temperature -moisture coupling. 【Conclusion】 Increasing soil moisture increased HCl-P, Citrate-P, Enzyme-P and Olsen-P in all soils. Increasing soil temperature increased HCl-P and Olsen-P, while reducing Citrate-P. Among all P forms we measure, only CaCl2-P and Enzyme-P were jointly affected by soil water and temperature. In a certain range, the effects of temperature and moisture on bioavailability of different P forms are integrative in all four soils we studied.

Keywords

• soil phosphorus
• soil moisture
• temperature
• p bioavailability
• hydrothermal effect