ARS | Publication request: Assessing Potential Soil Organic Carbon Sequestration in Forage-Based Cow-Calf Congregation Sites and Adjoining Pastures

Submitted to: ASA-CSSA-SSSA Annual Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: November 4, 2007
Publication Date: N/A

Technical Abstract: Grazing animals have a dominant effect on the movement and utilization of nutrients through the soil and plant system. Grazing can accelerate and alter the timing of nutrient transfers, and increase the amount of nutrients cycled from plant to soil. Our reason for conducting this study is to test whether cattle congregation sites (CCS) typical on most Florida ranches, such as mineral feeders, water troughs, and shade areas have higher soil organic carbon (SOC) than in other pasture locations under Florida conditions. Baseline soil samples around the congregations sites (mineral feeders, water troughs, and shades) in established (>10 yr), grazed cow-calf pastures were collected in the fall and spring of 2003, 2004, and 2005, respectively. Soil samples were collected from two soil depths (0-20 and 20-40 cm) at different locations around the congregation sites following a radial (every 90 degrees: N, S, E, W) sampling pattern at 0.9, 1.7, 3.3, 6.7, 13.3, 26.7, and 53.3 m away from the approximate center of mineral feeders, water troughs, and shaded areas. The levels of SOC vary significantly with CCS, distance away from the center of the CCS, sampling depth, and the interaction of CCS and soil depth. Sampling orientations did not significantly affect the levels of SOC. Water trough sites had the highest level of SOC of 3.58 g/kg, followed by shade sites (3.47 g/kg) and mineral feeder sites (2.98 g/kg). The levels of SOC (averaged across CCS) near the center (0.9 m) of the CCS was about 3.29 g/kg compared with 3.17 g/kg SOC at the furthest site (53.3 m). The average SOC of 4.16 g/kg in surface soil (0-20 cm) was significantly higher than that of the subsoil (20-40 cm) with mean SOC of 2.47 g/kg.