Growth of Rye and Cotton in a Rye-Cotton-Wheat Rotation as Affected by Cattle Grazing.
Fujiang Hou1, Vivien Allen1, Philip Brown1, and Changgui Wan2. (1) Texas Tech University, Department of Plant and Soil Science, Box 42122, Lubbock, TX 79409-2122, (2) Department of Rangeland Wildlife and Fish Management, Texas Tech University, Lubbock, TX 79409-2125
Use of small grains as cover crops prior to row crops can reduce erosion and improve nutrient cycling. Small grains offer opportunities for grazing by livestock but the impact of grazing on soils and plants is not well understood. In an 8-yr experiment, rye was planted each September and was grazed by steers from January until early April. Rye (Secale cereale) was then terminated and cotton (Gossypium hirsutum) was no-till planted into residue. Following cotton harvest, wheat (Triticum aestivum) was no-till planted and was grazed by steers the following spring. After grazing of wheat was completed, land was fallowed until rye was again planted in September. The experiment was a randomized complete block design with 3 replicates. Permanently located areas in each paddock were caged each year during grazing to prevent animal impact but were managed in all other ways as the grazed areas. In the 8th yr, a second cage was placed adjacent to the original cage to investigate the effect of previous years grazing or zero-grazing on growth of rye. Soil moisture in ungrazed areas was less (P < 0.01) than that under grazing. In areas that were never grazed, plant populations, plant basal cover, tiller numbers, tiller weights, total biomass, and plant heights were less (P < 0.001) than where grazing had occurred during the previous 7 yr. At the end of grazing, biomass in non-grazed areas was removed at a height similar to the grazed height. Height and density of cotton plants were greater (P < 0.01) when no-till planted into grazed than non-grazed rye. Our results indicate that exclusion of grazing from rye was detrimental to growth and productivity of rye and to the following cotton crop and this effect persisted through the 2-yr rotation with cotton, wheat, and a fallow period.