Effects of long‐term phosphorus fertilizer inputs and seasonal conditions on organic soil phosphorus cycling under grazed pasture

Abstract

Soil microbes and phosphatase enzymes play a critical role in organic soil phosphorus (P) cycling. However, how long-term P inputs influence microbial P transformations and phosphatase enzyme activity under grazed pastures remains unclear. We collected top-soil (0-75 mm) from a grazed pasture receiving contrasting P inputs (control, 188 kg ha −1 year −1 of single super phosphate [SSP], and 376 kg ha −1 year −1 of SSP) for more than 65 years. Olsen P, microbial biomass P, and acid and alkaline phosphatase enzyme activities were measured regularly over a 2-year period. Pasture dry matter and soil chemical properties were also investigated. Results showed that long-term P inputs significantly increased pasture dry matter, total N, and the concentrations of NO − 3 -N but significantly decreased soil pH and the concentrations of NH + 4 -N. Total C was not affected by P fertilization. Although Olsen P significantly increased with increasing long-term P inputs, microbial biomass P was similar under P fertilized treatments. Long-term P inputs decreased acid phosphatase activity but increased alkaline phosphatase activity. Microbial biomass P was similar across seasons in the control but decreased in spring and autumn while increased in summer and winter under P fertilized treatments. Acid and alkaline phosphatase activities were significantly affected by season and followed similar seasonal trends being maximum in summer and minimum in winter regardless of P treatment. Correlation and principal component analysis revealed that acid and alkaline phosphatase activities were significantly positively correlated with soil temperature and significantly negatively correlated with soil moisture. In contrast, Olsen P and microbial biomass P were weakly correlated with environmental conditions. The findings of this study highlight the intertwined relationship between organic P cycling and the availability of C and N in soil systems and the need to integrate both soil moisture and temperature in models predicting organic P mineralization, especially in the context of global climate change.

Green manure incorporation enhanced soil labile phosphorus and fruit tree growth

“…In response to a P i -limited soil environment, microorganisms tend to release a higher quantity of phosphatases ( Bergkemper et al., 2016 ). These enzymes are capable of effectively hydrolyzing ester-phosphate bonds in various phosphate-esters, thereby promoting the mineralization of soil insoluble P. This process enhances the overall effectiveness of P in the soil and facilitates its availability for biological uptake and cycling ( Lu et al., 2022 ; Touhami et al., 2023 ).…”

Role of Soil Microbiota Enzymes in Soil Health and Activity Changes Depending on Climate Change and the Type of Soil Ecosystem

“…AcP and AlP linked positively with soil temperature but negatively with SM. [246] Two cotton cultivars and three phosphorus (P) levels. A pot experiment was conducted in 2017 at the Baibi station, Anyang, Henan, China…”