Abstract
Generally, improvement in the soil health of pasturelands can result in amplified ecosystem services which can help improve the overall sustainability of the system. The extent to which specific best management practices have this effect has yet to be established. A farm-scale study was conducted in eight beef-pastures in the Southern Piedmont of Georgia, from 2015 to 2018, to assess the effect of strategic-grazing (STR) and continuous-grazing hay distribution (CHD) on soil health indicators and runoff nitrate losses. In 2016, four pastures were converted to the STR system and four were grazed using the CHD system. Post-treatment, in 2018, the STR system had significantly greater POXC (by 87.1, 63.4, and 55.6 mg ha−1 at 0–5, 5–10, and 10–20 cm, respectively) as compared to CHD system. Soil respiration was also greater in the STR system (by 235 mg CO2 m-2 24 h−1) and less nitrate was lost in the runoff (by 0.21 kg ha−1) as compared to the CHD system. Cattle exclusion and overseeding vulnerable areas of pastures in STR pastures facilitated nitrogen mineralization and uptake. Our results showed that the STR grazing system could improve the sustainability of grazing systems by storing more labile carbon, efficiently mineralizing soil nitrogen, and lowering runoff nitrate losses.
Highlights
The growing cognizance of scientists and producers on soil health and its implication on agricultural sustainability has propelled research works on creating management strategies for improving soil health [1,2,3] in various agroecosystems
The STR and continuous-grazing hay distribution (CHD) pastures experienced 24.7 mg kg−1 and 24.4 mg kg−1 increase, respectively, from baseline to 2018 at 0–5 cm soil depth. This result corroborates with our argument that the pool of Potentially mineralizable nitrogen (PMN) was efficiently mineralized to add to the inorganic N pool. The findings from another part of this study showed that the soil organic carbon pool was mineralized, and in the process, nitrogen was released to add to the inorganic nitrogen pool [41]
Promising positive changes in ecosystem services came from the strategic grazing system including an increase in active carbon, consistent respiration rate, and cleaner runoff water with a reduction in nitrate in runoff water
Summary
The growing cognizance of scientists and producers on soil health and its implication on agricultural sustainability has propelled research works on creating management strategies for improving soil health [1,2,3] in various agroecosystems. The United States has about 308 million ha of grazing lands, which is approximately 31% of the total land area [7,8] This area provides numerous ecosystem services and is an important contributor to the national GDP (gross domestic product). In the Southeastern USA, we define conventional grazing systems as pastures continuously grazed with little control over grazing time in specific locations within pastures. This results in cattle-preference to certain areas [13,14], leading to uneven nutrient distribution [15,16] and inefficient land utilization. High cattle activity near pasture equipages (water, shade, hay, mineral blocks, etc.) in the conventional system results in nutrient hotspots, soil compaction [17,18], and erosion resulting in poor fertility and vegetative cover in these steep, marginal areas of the pastures which exacerbates the ecosystem’s vulnerability to runoff losses
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