Project Overview
Information Products
Commodities
- Agronomic: cotton
- Animals: sheep
Practices
- Pest Management: prevention
- Production Systems: integrated crop and livestock systems
Abstract:
The economic opportunity represented by organic cotton premiums has captured the interest and commitment of many producers across the South. Semi-arid West Texas is conducive to successful organic cotton production. However, mechanical- and hand-weed control are neither environmentally nor economically sustainable options. Sheep integration in organic cotton systems has potential to suppress weeds and add value to the overall production system. Due to limited water, portions of irrigated land are often rotated with grain or forage crops with different timing of water demands. A new system, integrating sheep, cotton, annual forages, and perennial forages offers unique potential for diversification and ecological resilience.
A participatory research framework was employed to engage stakeholders with the research process and gain understanding of factors influencing producer management decisions relative to new or alternative practices. Field research trials were coordinated on the integration of sheep as natural weed control option in cotton systems and best-suited perennial and annual forages for a livestock integrated cropping system. Economic assessments were performed to identify changes in revenue vs. expenses, estimating ultimate changes in profitability relative to varying system components.
Trials assessing the effect of sheep grazing intensity and timing (cotton growth stage) indicated that sheep spent 87%, 86%, and 93% of feeding time grazing weeds rather than cotton with grazing initiated at the 4-leaf, 8-leaf, and mid-bloom stages, respectively. This supported the hypothesis that palatability of cotton declines with increasing maturity. Final cotton biomass was not influenced by year, intensity, or timing of sheep grazing treatments, but was greater when cotton was maintained weed-free without sheep. Final weed biomass was affected by year (P > 0.069) and timing of grazing (P > 0.036). Notably, grazing initiated at the 4-leaf stage resulted in greater weed biomass at the end of the growing season than grazing initiated at the 8-leaf stage. The key implication is that grazing too early imposed too much damage on the cotton, limiting the duration of the grazing event and lowering overall potential for weed removal.
Additional research assessed the effects of previous exposure to cotton and conditioned taste aversion on lamb weed vs. cotton feeding. Lambs previously familiar with cotton consumed more cotton than lambs with a conditioned taste aversion. Lambs typically selected grass and forbs, while foraging, and selection of cotton was not correlated with selection of herbaceous weeds (r2 = 0.02). Regardless of prior exposure or conditioning, lambs reduced weed cover when compared to ungrazed plots.
Experience from these field research trials underscored the challenge of extrapolating small-plot research to field scale, as sheep grazing behavior is influenced by stocking density. Integrating sheep grazing into production systems shows promise for farmers seeking reduced herbicide/organic management, but further refinement and consideration of economic impacts are necessary. Future research may assess grazing preferences relative to sheep age and breed to provide greater insight into integrated crop-livestock management practices.
Native perennial forage trials at Lubbock, TX indicated that the ratio of grasses to forbs included in the mix had no main or interactive effect with any other variable. Cover % was influenced by the interaction of sampling date and cover type. Cover by volunteer forb species increased from fall 2024 to 2025, while bare ground decreased. No forbs that were included in the mixes germinated between fall 2024 – fall 2025. The primary volunteer forb species include kochia, Russian thistle, and bitter sneezeweed. Grass cover was also low (< 10%) at each sampling event. Of the three grass species included in the mixes (blue grama (BOGR), buffalograss (BODA), and western wheatgrass), two were recorded in the plots and both are increased in cover as the study progressed. Volunteer grass species included sandbur and windmill grass. Both of these species have decreased in cover since fall 2024. Perennial forage trials at San Angelo demonstrated similar inefficacy of seeding forbs with native grasses, and resulted in primarily side oats grama with sparse buffalograss and considerable broadleaf weed presence, regardless of treatment effects. Across multiple attempts in different years at both locations, establishment of native perennial forages on degraded cropland was very slow, challenged with weeds, and did not result in establishment of the majority of species planted. Forage nutritive value was largely poor, indicating that protein supplementation may be needed if exclusively grazing these forages.
Due to challenges with diverse native species establishment, an additional field trial was coordinated on improved perennial cool-season forage grasses and alfalfa at Wall, TX. Alfalfa resulted in the greatest biomass, followed by tall wheatgrass and tall fescue. Orchardgrass did not yield well, and establishment was poor with intermediate wheatgrass. Trials testing various species and varieties of annual forages indicated that Austrian winter pea and hairy vetch are well-suited among winter annual legumes. Grass legume mixtures were challenged by excessive competition from the grass, and has informed ongoing research on optimum grass seeding rate and planting configuration in species mixtures.
One of the potential benefits of using herbivory for weed control is the savings achieved through reduced herbicide use. Economic assessment indicated that if grazing is successfully used to completely replace herbicide use, this results in a total savings of $105.17 per hectare. The best economic outcome occurred when sheep grazing was implemented at the 8-leaf cotton growth stage to with a lower threshold to terminate grazing (70% weed removal), which aligns with a lower tolerance for grazing damage to the cotton. This resulted in an increase of $198.12 per hectare. In addition to the ecological benefits, sheep grazing as a means of weed control can bear economic merit.
Research components of this work resulted in two graduate research theses, contributing significantly to educational and professional development. Findings were presented at various Extension programs and NRCS workshops, as well as the Texas Sheep and Goat Field Day, Texas Plant Protection Conference, the Beltwide Cotton Conferences, Weed Science Society of America, and the ASA, CSSA, SSSA International Annual Meetings. Development of research and Extension products are ongoing, and outcomes will continue to be shared via field days, newsletters, and local grower meetings.
Project objectives:
Objective 1. Employ Neef and Neubert’s six dimensions of participatory research framework to facilitate positive, favorable interaction between researchers and stakeholders and enhance the viability and livelihood of organic cotton stakeholders in the South.
- Coordinate needs assessment via Q-methodology to explore stakeholder perspectives, needs, and expected benefits and outcomes of the proposed project.
- Establish a project advisory board
- Host regular town-hall meetings to convene with stakeholder groups on research progress and direction.
Objective 2. Assess agronomic and stocking management implications of sheep-weeding in cotton
a. Year 1: Evaluate timing of sheep-weeding initiation relative to cotton growth stage, and sheep-weeding termination relative to varying thresholds of weed herbage mass removal.
b. Years 2 and 3: Compare optimized sheep weeding strategy (from Obj. 2a) to alternative and otherwise standard weed management systems.
Objective 3. Identify best-suited perennial and annual forage management options for converted land
a. Test establishment success, forage yield and nutritive value, and soil health indicators across a range of forb inclusion rates with native perennial grasses.
b. Assess forage yield, nutritive value, and sheep grazing preference among summer and winter annual legumes and legume-grass mixtures.
Objective 4. Develop, deliver, and test public resources, economic decision support tools, and stakeholder resources for continued education and assessment of sheep-weeding practices.
a. Economic enterprise budgets informed by measurements in Objectives 2 and 3.
b. Develop and deploy reusable learning modules
c. Publish findings in popular press articles and develop educational videos