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Legume-grass mixtures are often used to increase forage yield and soil fertility in managed grasslands, but it remains unclear whether these benefits could be further improved by utilizing optimal legume-grass seeding ratios and phosphorus (P) fertilization. Here, we conducted a 5-year field experiment across 3 sites to investigate the effects of legume-grass seeding ratio and P fertilization on forage yield and soil quality. This experiment included mixtures comprised of two legume species and two grass species at five legume-grass ratios (3:7, 4:6, 5:5, 6:4, and 7:3), and monoculture of each species. P fertilizer was applied at the rate of 0, 9, 18, or 27 kg P ha-1 year-1. Plant diversity effects, e.g., complementarity and selection effects, were assessed by comparing yield of mixtures with monocultures. Our results show that a legume-grass mixture with a seeding ratio of 3:7 under moderate P fertilization resulted in the highest forage yield among all monocultures and mixtures, for each of the three sites, with persistent and consistent transgressive overyielding. Notably, greater soil organic matter, total nitrogen, enzymatic activity, and microbial biomass were observed with the legume-grass ratio of 3:7, compared to monocultures or other seeding ratios. Structural equation modeling indicated that the legume-grass ratio of 3:7 achieved highest yield through directly improving complementarity effect, and indirectly promoting selection effects because of increased fungal biomass. P fertilization directly enhanced soil nutrient and enzymatic activities, and further improved complementarity effect, resulting in high forage yield and soil quality. These results indicate that forage diversification practices with low legume-grass seeding ratios and moderate P fertilization can simultaneously benefit forage production and soil quality in managed grasslands. Overall, our study suggests that low legume seeding proportion in legume-grass mixtures combined with moderate nutrient management is a useful strategy for sustainable and highly productive managed grasslands. [ABSTRACT FROM AUTHOR]

Ungulate grazing involves multiple components, including defoliation, dung and urine return, and trampling, which supply offsetting or synergistic effects on plant community composition and productivity (ANPP), but these effects have not been fully studied. Plant functional traits may reflect the response of plants to disturbance and their impact on ecosystem functions. Species turnover and intraspecific trait variation (ITV) are important drivers of community trait composition. We conducted a simulated grazing experiment in a steppe grassland in northern China to examine the effects of defoliation, dung and urine return, and trampling on community-weighted mean (CWM), functional diversity (FD) and ANPP, and to disentangle the roles of species turnover and ITV in driving these changes. We found that defoliation had a dominant effect on CWMs and FDs of all four traits through species turnover and ITV, respectively, resulting in a convergence of traits towards as more resource-acquisitive strategy. Dung-urine return resulted in more resource-acquisitive community traits mainly through ITV, whereas there were no significant effects on FDs except for leaf C/N. Trampling increased CWM of leaf dry matter content primarily driven by ITV, and had no significant effect on FDs. Furthermore, our simulated grazing positively affected ANPP, primarily due to nutrient additions from dung and urine, and ITV largely explained the variation in ANPP. These findings highlight the multifaceted effects of grazing components on community structure and ANPP, and the significance of ITV in shaping grassland plant communities and productivity. [ABSTRACT FROM AUTHOR]

Plant carbon (C) input via litter decomposition is essential for forming soil organic C (SOC). Previous studies have investigated the fate of litter C through one-time litter addition, while litter input could be recurrent, e.g., gradual litter input from above-ground plant material in diverse ecosystems. This paper investigates how litter input's frequency (single vs. repeated) and amount (low vs. high) affect the SOC formation and the associated microbial community composition and activity in a controlled microcosm experiment. After incubating the 13C-labeled litter (Stipa krilovii) for 80 days with the fresh field soil collected from a semi-arid steppe in Inner Mongolia, China, we measured newly formed SOC, microbial biomass C (MBC), and microbial phospholipid fatty acid (PLFA) indicated by 13C-labeling. The repeated litter addition resulted in 19.92% greater and 12.45% more efficient SOC formation than the single addition. Repeated litter addition also increased C use efficiency (CUE, + 76.71%), indicating more substrate C allocated for microbial growth than respiration. It also enhanced the fungi to bacteria ratio by 47.40% (based on 13C-PLFA) and maintained relatively stable microbial assimilation of litter C (based on 13C-MBC). These findings were consistent regardless of litter amounts. Our results indicate that the uninterrupted litter input to the soil in natural ecosystems benefits SOC formation and highlights soil fungi's critical role in promoting SOC formation. This study suggests that incorporating plant C input frequency into SOC dynamic models may improve the predictions of C cycling. [ABSTRACT FROM AUTHOR]

Many studies have concentrated on fixed cost and resource allocation issues by using data envelopment analysis (DEA). The existing approaches allocate fixed cost or resource primary based on efficiency principle. They usually assume that all of the DMUs become efficient after fixed cost or resource allocation. However, due to the existing of technology heterogeneity among DMUs, it is impractical for all the DMUs to achieve a common technology level, especially when some DMUs are far from the efficient frontier. In this paper, under the centralized decision environment, we present a new approach to deal with fixed cost and resource allocation problems by considering the factor of technology heterogeneity. Specifically, the concepts of meta-efficiency and group efficiency as well as meta-technology ratio are firstly introduced to reflect the technology level of the DMUs. Then two centralized DEA models considering technology heterogeneity are proposed to allocate fixed cost and resources, respectively. Finally, two numerical examples are presented to illustrate the feasibility and superiority of the proposed approach compared with prior studies. [ABSTRACT FROM AUTHOR]