Soil phosphorus chemistry: A systems approach.

摘要

The grassland soil ecosystem emulates a no-till agroecosystem and, therefore, provides a unique system to study management effects on both soil and plant physicochemical nutrient cycling mechanisms. Hence, the objective of this research was to study specific physicochemical mechanisms and factors regulating the distribution of P in grassland agroecosystems.;Native tallgrass upland prairie soil is extremely low NaHCO;Phosphorus and nitrogen fertilization in grassland soil may alter the nutrient cycling processes by affecting both the inorganic and organic soil P chemistry. The soil P chemistry in a long-term fertilized brome grass experiment (40 years of N and P fertilization) was assessed using both a soil chemical equilibria and a sequential P fractionation method. Phosphorus fertilization significantly increased the quantity of P in the inorganic P fractions to a depth of 30 cm. Soil chemical equilibrium experiments revealed the soil inorganic chemistry followed thermochemical principles. Variscite appears to be a stable secondary P mineral formed by excessive N and P fertilization. The sequential P fractionation indicates phosphorus fertilization did not significantly increase the soil Po content. In contrast, N fertilization significantly increased the labile soil organic P content for soil samples taken in the summer of 1988. These results suggest long-term P cycling mechanisms were controlled by the inorganic P fractions.