Adaptive multi-paddock grazing management's influence on soil food web community structure for: increasing pasture forage production, soil organic carbon, and reducing soil respiration rates in southeastern USA ranches.

Background: Measurement of two grazing management's influence on pasture productivity, soil food web structure, soil organic carbon and soil microbial respiration efficiency was conducted on five southeastern US, across-the-fence ranch pairs to compare adaptive multi-paddock grazing (AMP) management, using short grazing events with planned, adaptive recovery periods, to conventional grazing (CG) management, with continuous grazing at low stock density. Methodology: A point-in-time experimental field analysis was conducted to compare five AMP or CG ranch pairs to better understand the influence of grazing management on (a) standing crop biomass productivity; (b) soil food web community population, structure and functionality; (c) soil organic carbon accrual; and d) soil-C (CO2) respiration kinetics. Results: AMP grazing systems outperformed CG systems by generating: (a) 92.68 g m-2 more standing crop biomass (SCB), promoting 46% higher pasture photosynthetic capacity (Two sample Mann-Whitney; Z = 6.1836; no DF in MW; p = 6.26 × 10-10; Effect size = 0.35) (b) a strong positive linear relationship of SCB with fungal biomass (R = 0.9915; F(1,3) = 175.35; p = 0.015); fungal to bacterial (F:B) biomass ratio (R = 0.9616; F(1,3) = 36.75; p = 0.009) and a soil food web proxy (R = 0.9616; F(1,3) = 36.75; p = 0.009) and a concurrent very strong inverse relationship with bacteria biomass (R = -0.946; F(1,3) = 25.56; p = 0.015); (c) significant predator/prey interactions with an inverse relationship with bacterial population biomass (R =  - 0.946; F(1,3) = 25.56; p = 0.015) and a positive relationship with total protozoa enumeration (R = 0.9826; F(1,3) = 83.68; p = 0.003) when compared to SCB; (d) a 19.52% reduction in soil C (CO2) respiration rates (Two sample t-test; T = -2.3581; DF = 52.3541; p = 0.0221; Effect size = 0.59); and (e) a 20.6% increase in soil organic carbon (SOC) in the top 10 cm of soil profile (Two sample Mann-Whitney; Z = 2.6507; no DF in MW; p = 0.008; Effect size = 0.24). Rancher conversion to AMP grazing strategies would appear to regenerate soil food web population, structure, diversity and biological functionality helping to improve: carbon flow into plant biomass, buildup of soil carbon, predator/prey nutrient cycling and soil microbial respiration efficiency while offering improved climate resilience and a strategy to increase the capture and storage of atmospheric CO2 in soils of the world's rangeland.

Vegetation, water infiltration, and soil carbon response to Adaptive Multi-Paddock and Conventional grazing in Southeastern USA ranches.

We examine Adaptive Multi-Paddock (AMP) grazed with short grazing events and planned recovery periods and paired ranches using Conventional Continuous Grazing (CG) at low stock density on vegetation, water infiltration, and soil carbon across SE USA. Increased vegetation standing biomass and plant species dominance-diversity were measured in AMP grazed ranches. Invasive perennial plant species richness and abundance increased with AMP grazing in the south, while in the north they increased on CG grazed ranches. Percent bare ground was significantly greater in CG at the Alabama and Mississippi sites, no different at the Kentucky and mid-Alabama sites, and greater on AMP at the Tennessee pair. On average, surface water infiltration was higher on AMP than paired CG ranches. Averaged over all locations, soil organic carbon stocks to a depth of 1 m were over 13% greater on AMP than CG ranches, and standing crop biomass was >300% higher on AMP ranches. AMP grazing supported substantially higher livestock stocking levels while providing significant improvements in vegetation, soil carbon, and water infiltration functions. AMP grazing also significantly increased available forage nutrition for key constituents, and increased soil carbon to provide significant resource and economic benefits for improving ecological health, resilience, and durability of the family ranch.

Adaptive multi-paddock grazing enhances soil carbon and nitrogen stocks and stabilization through mineral association in southeastern U.S. grazing lands.

Grassland soils are a large reservoir of soil carbon (C) at risk of loss due to overgrazing in conventional grazing systems. By promoting regenerative grazing management practices that aim to increase soil C storage and soil health, grasslands have the potential to help alleviate rising atmospheric CO2 as well as sustain grass productivity across a vast area of land. Previous research has shown that rotational grazing, specifically adaptive multi-paddock (AMP) grazing that utilizes short-duration rotational grazing at high stocking densities, can increase soil C stocks in grassland ecosystems, but the extent and mechanisms are unknown. We conducted a large-scale on-farm study on five "across the fence" pairs of AMP and conventional grazing (CG) grasslands covering a spectrum of southeast United States grazing lands. We quantified soil C and nitrogen (N) stocks, their isotopic and Fourier-transform infrared spectroscopy signatures as well as their distribution among soil organic matter (SOM) physical fractions characterized by contrasting mechanisms of formation and persistence in soils. Our findings show that the AMP grazing sites had on average 13% (i.e., 9 Mg C ha-1) more soil C and 9% (i.e., 1 Mg N ha-1) more soil N compared to the CG sites over a 1 m depth. Additionally, the stocks' difference was mostly in the mineral-associated organic matter fraction in the A-horizon, suggesting long-term persistence of soil C in AMP grazing farms. The higher N stocks and lower 15N abundance of AMP soils also point to higher N retention in these systems. These findings provide evidence that AMP grazing is a management strategy to sequester C in the soil and retain N in the system, thus contributing to climate change mitigation.