Mowing accelerates phosphorus cycling without depleting soil phosphorus pool

Mowing, as a common grassland utilization strategy, affects nutrient status in soil by plant biomass removal. Phosphorus (P) cycle plays an important role in determining grassland productivity. However, few studies have addressed the impacts of mowing on P cycling in grassland ecosystems. Here, we investigated the effects of various mowing regimes on soil P fractions and P accumulation in plants and litters. We specifically explored the mechanisms by which mowing regulates ecosystem P cycling by linking aboveground community with soil properties. Our results showed that mowing increased soil dissolvable P concentrations, which probably met the demand for P absorption and utilization by plants, thus contributing to an increased P accumulation by plants. Mowing promoted grassland P cycling by a reciprocal relationship between plants and microbes. Short-term mowing enhanced P cycling mainly through increased root exudation-evoked the extracellular enzyme activity of microbes rather than the alternations in microbial biomass and community composition. Long-term mowing increased P cycling mainly by promoting carbon allocation to roots, thereby leading to greater microbial metabolic activity. Although mowing-stimulation of organic P mineralization lasted for 15 consecutive years, mowing did not result in soil P depletion. These results demonstrate that P removal by mowing will not necessarily lead to soil P limitation. Our findings would advance the knowledge on soil P dynamic under mowing and contribute to resource-efficient grassland management.

Automated summary

Mowing as a grassland utilization strategy affects soil nutrient status by removing plant biomass. This study investigated the impacts of various mowing regimes on soil phosphorus (P) fractions, P accumulation in plants and litters, and the mechanisms of mowing in regulating P cycling in grassland ecosystems. The results showed that mowing increased soil dissolvable P concentrations, contributing to increased P accumulation in plants. Short-term mowing enhanced P cycling through increased root exudation-evoked microbial enzyme activity, while long-term mowing increased P cycling by promoting carbon allocation to roots and greater microbial metabolic activity. These findings advance our understanding of soil P dynamics under mowing and contribute to resource-efficient grassland management.