Rotational grazing can mitigate ecosystem service trade‐offs between livestock production and water quality in semi‐arid rangelands

Application of multi-criteria group decision-making for water quality management

As waste discharge into numerous river systems escalates, the pollution of water bodies typically rises. Given the limited capacity of rivers to withstand pollution and their constrained self-cleaning capabilities, treated pollutants from waste discharge must be released into the river. Despite numerous models and algorithms proposed for managing river water quality to meet standards, literature, to our awareness, lacks the utilization of a comprehensive multi-criteria group decision-making approach for water quality management, particularly in river systems. Therefore, this research introduces a new, comprehensive multi-criteria group decision-making for the management of water quality in the Haraz River basin, located in Iran. To do so, the water quality of the basin, a one-dimensional water quality model, QUAL2Kw, was employed to simulate and calibrate the water quality along the river. The simulation results revealed that the downstream water quality violates the water quality standards. To mitigate this issue, various scenarios for waste load allocation (WLA) were evaluated, including no wastewater treatment, primary wastewater treatment, advanced secondary wastewater treatment utilizing the activated sludge (AS) method, and advanced wastewater treatment via the membrane bioreactor (MBR) method. Utilizing the Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) and Fuzzy TOPSIS group decision-making model, it was determined that the optimal solution was the implementation of secondary wastewater treatment utilizing the activated sludge method for the 11 PS of pollution, while still adhering to Iranian water quality standard. In addition, the findings of the present study indicate that the implementation of primary wastewater treatment, advanced secondary wastewater treatment utilizing AS, and advanced wastewater treatment through MBR within the study area led to a significant enhancement in water quality. This enhancement ranged from 35 to 105% across various scenarios when compared to conditions where no actions were taken to the treatment of water.

Escherichia coli efflux from rangeland ecosystems in the southcentral Great Plains of the United States

Bacterial contamination of surface water is a public health concern. To quantify the efflux of Escherichia coli into ephemeral and intermittent streams and assess its numbers in relation to secondary body contact standards, we monitored runoff and measured E. coli numbers from 10 experimental watersheds that differed in vegetation cover and cattle access in north-central Oklahoma. Escherichia coli numbers were not significantly different among the watersheds, with one exception; the grazed prairie watershed (GP1) had greater numbers compared to one ungrazed prairie watershed (UP2). Median E. coli numbers in runoff from ungrazed watersheds ranged from 260 to 1482 MPN/100 mL in comparison with grazed watersheds that ranged from 320 to 8878 MPN/100 mL. In the GP1 watershed, higher cattle stocking rates during pre- and post-calving (February-May) resulted in significantly greater bacterial numbers and event loading compared to periods with lower stocking rates. The lack of significance among watersheds is likely due to the grazed sites being rotationally (and lightly) grazed, data variability, and wildlife contributions. To address wildlife sources, we used camera trap data to assess the usage in the watersheds; however, the average number of animals in a 24-h period did not correlate with observed median E. coli numbers. Because of its impacts on E. coli numbers in water, grazing management (stocking rate, rotation, and timing) should be considered for improving water quality in streams and reservoirs.

Agriculture specialization influence on nutrient use efficiency and fluxes in the St. Lawrence Basin over the 20th century

Increasing the overall use efficiency of nitrogen (N) and phosphorus (P) resources in food production while minimizing losses to the environment are required to meet the dual challenge of food security and sustainability. Yet studies quantifying the overall performance of different agro-system types and how these have changed over time remain rare, although they are essential to propose solution pathways. Here, we reconstructed fluxes of N and P within 78 watersheds of the St. Lawrence Basin (SLB) of eastern Canada between 1901 and 2011, using the Generalized Representation of Agro-Food System model (GRAFS). This analysis allowed us to classify different agro-food system types and to evaluate how agricultural specialization influenced nutrient efficiencies and potential losses to the environment over time. Using a cluster analysis, we identified four agro-food system types with different overall outcomes in efficiencies and losses. We show that agricultural practices in the SLB were similar until the 1950's and deemed unsustainable in several watersheds by depleting agricultural soils of their nutrients (particularly N). With the advent of manufactured fertilizers and the intensification of livestock farming, the SLB then rapidly shifted through the 1970s and 1980s to more intensified and highly unsustainable agro-food system types, where, in 2011, ~77 % of N and ~ 94 % of P inputs were lost to the environment. We also show that nutrient pollution continued to increase despite gains in the nutrient use efficiency of animal farming due to higher nutrient throughput from intensive production. The increased proportion of confined animals, disconnected from croplands, indeed resulted in inefficient nutrient recycling. While nutrient use efficiency may mitigate nutrient pollution, reducing the absolute nutrient flux through agro-food systems should be a priority, likely through a reconnection of crop and animal farming and an overall reduction of meat production, specifically from concentrated, intensive livestock systems.

Improved management of farm dams increases vegetation cover, water quality, and macroinvertebrate biodiversity

In many farming landscapes, aquatic features, such as wetlands, creeks, and dams, provide water for stock and irrigation, while also acting as habitat for a range of plants and animals. Indeed, some species threatened by land-use change may otherwise be considerably rarer-or even suffer extinction-in the absence of these habitats. Therefore, a critical issue for the maintenance of biodiversity in agricultural landscapes is the extent to which the management of aquatic systems can promote the integration of agricultural production and biodiversity conservation. We completed a cross-sectional study in southern New South Wales (southeastern Australia) to quantify the efficacy of two concurrently implemented management practices-partial revegetation and control of livestock grazing-aimed at enhancing the vegetation structure, biodiversity value, and water quality of farm dams. We found that excluding livestock for even short periods resulted in increased vegetation cover. Relative to unenhanced dams (such as those that remained unfenced), those that had been enhanced for several years were characterized by reduced levels of turbidity, nutrients, and fecal contamination. Enhanced dams also supported increased richness and abundance of macroinvertebrates. In contrast, unenhanced control dams tended to have high abundance of a few macroinvertebrate taxa. Notably, differences remained between the macroinvertebrate assemblages of enhanced dams and nearby "natural" waterbodies that we monitored as reference sites. While the biodiversity value of semilotic, natural waterbodies in the region cannot be replicated by artificial lentic systems, we consider the extensive system of farm dams in the region to represent a novel ecosystem that may nonetheless support some native macroinvertebrates. Our results show that management interventions such as fencing and grazing control can improve water quality in farm dams, improve vegetation structure around farm dams, and support greater abundance and diversity of aquatic macroinvertebrates.