The pattern of soil microbe metabolic limitation was altered by the increased sheep grazing intensity in two contrasting grasslands: Implications for grassland management in semiarid regions

Abstract

Soil extracellular enzyme stoichiometry (EES) and microbial metabolic limitation deeply reflect soil quality. However, knowledge about the impacts of different grazing intensities on microbial metabolic limitation has not been well-documented.Herein, the influences of four sheep grazing intensities (ungrazed, UG; lightly grazed,LG; moderately grazed, MG; and heavily grazed, HG) on microbial metabolic limitation were investigated in typical steppe (14-year grazing) and desert steppe (17-year grazing). The activities of an extracellular enzyme (EEAs) involved in soil C, N, and P transformation were determined by fluorimetric microplate assay. We found that different grazing intensities significantly affected extracellular enzyme activities and EES. Compared to the treatments of UG, LG, and MG, microbial relative C limitation

Soil Cations Explain the Variation of Soil Extracellular Activities and Microbial Elemental Limitations on Subtropical Grassland, China

“…Results showed that soil available calcium (p = 0.0099), magnesium (p = 0.0099), and potassium (p = 0.0099) were identified as the most crucial factors that significantly explained the variation of soil microbial C limitation. This was also different from a recent finding from sheep grazing studies, which suggested that soil organic carbon and total nitrogen significantly affect soil microbial carbon limitation [11]. Furthermore, soil available calcium (p = 0.0099) and magnesium (p = 0.0198) were identified as the most crucial factors that significantly explained the variation of soil microbial nutrient (nitrogen and phosphorus) limitation (Fig.…”

“…Ding et al [10] showed that grazing exacerbated the microbial carbon limitation of surface soil. Soil extracellular enzyme activity and microbial resource limitation profoundly reflect soil quality [11] and impact the carbon use efficiency of soil microbiota [12]. Therefore, understanding soil enzyme activity and soil microbial element resource limitations can enhance our understanding of soil carbon and nutrition supply from the perspective of microbial communities [9].…”

“…Therefore, understanding soil enzyme activity and soil microbial element resource limitations can enhance our understanding of soil carbon and nutrition supply from the perspective of microbial communities [9]. Nevertheless, the impact of grazing on soil enzyme activity and soil microbial element resource limitations is still not fully understood [11], especially in the subtropical grasslands of southern China.…”

Microbial phosphorus‐cycling genes in soil under global change

“…Due to the very slow weathering rates of parent materials and the strong affinity of di‐ and trivalent cations as well as calcium towards phosphate (Elser, 2012; Westheimer, 1987), P mainly exists as persistent organic and inorganic forms in soils, leading to prevalent deficiencies in bioavailable P in most ecosystems (Lekberg et al., 2021; Liu et al., 2023). In contrast to agricultural systems with P fertilization, the P loss from soil–plant cycling in grasslands is primarily replenished through the acceleration of P recycling from plant litter driven by microorganisms (Helfenstein et al., 2018; Zhang, Song, et al., 2023). Thus, clarifying the responses of soil microorganisms in the P cycle is increasingly recognized as a major priority in grassland ecosystem management and restoration.…”