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How do different grazing management systems affect soil health? To address this question, this project evaluated a suite of soil health indicators, and interrelationships with vegetation, under three different grazing management systems in northcentral Texas. Soil samples (0-15cm) were collected in April 2017 from ranches with three different grazing management systems: Ranch 1 (HSHF): high stocking rate and rotation frequency, Ranch 2 (MSMF): medium stocking rate and rotation frequency, and Ranch 3 (LSCG): low stocking rate with continuous grazing. Sampling sites were selected using soil maps and expert knowledge to identify locations with similar soil type, landscape position, and climate. Soil samples were shipped within 48 hours to Cornell Soil Health Lab for the Comprehensive Assessment for Soil Health (CASH), University of Missouri for microbial community composition using phospholipid fatty acid profiling, and, Dr. Haney’s lab in Temple, TX for the Soil Health Tool (SHT) Index. Plant community composition, diversity, and production potential were measured along each transect at the same time soil samples were collected.
In general, measured soil health differences (SOM, WHC, WEON) were slightly greater in MSMF system compared to LSCG system. Although sampling locations targeted similar soil types, clay content was an important covariate, indicating adjustments for this variable were necessary for proper interpretation of SOM and WHC. SOM and aggregate stability measures were decoupled from each other with the highest SOM ranch having the lowest aggregate stability score. From a soil health perspective, all three ranches exhibited effects of sound grazing management, with only subtle differences in a few soil health indicators; none of the ranches were in a degraded condition. Future analyses to explore economic differences and relationships among vegetation data and soil microbial community composition using molecular tools are pending.
Presenters: Jennifer Moore-Kucera1, Kristie A. Maczko2, Jeff Goodwin3
Affiliations: Soil Health Division, USDA Natural Resources Conservation Services1; Sustainable Rangelands Roundtable University of Wyoming2; Noble Resources Institute3