Sustainable Pasture Management in Texas: Optimizing forage production and nutrient use in various environments and soils

View the project final report

Commodities

• Agronomic: grass (misc. perennial)

Practices

• Animal Production: feed/forage

Weather events such as extreme temperatures, drought, and floods have become more frequent and intense across the U.S. in recent decades and are predicted to continue and present a challenge to pasture and forage production systems, and forage quality. In Texas, a severe drought in 2011/2012 caused billions of dollars of losses in livestock and hay production. Extreme events including drought and excess precipitation directly impact the physiological processes of a forage crop. These events also affect the timing of field operations. Moreover, increased amounts and intensity of precipitation cause increased soil erosion and nutrient loss by water, negatively impacting soil health and water quality.

Faced with the challenges of rising demand for animal food products and concerns over climate changes, expanded use of perennial grasses tolerant to these stresses become critical to reduce risks in pasture systems. Improved forage crop root functions are also important. Using deep rooted rhizomatous grasses as forage crops increases soil carbon storage and reduces impacts of flooding and soil erosion. Eastern gamagrass is a promising crop with high protein forage production under marginal environmental conditions and with co-benefits of water/soil conservation. However, its inconsistent stand establishment typical of native species have limited its use. This is related to seed dormancy, the need to pre-chill moistened seeds, or plant in the Fall to allow seed chilling. Unlike planting common cultivated crops, sprigging coastal bermudagrass, or planting introduced grasses, the probability of successful stand establishment of EG is low the initial year. Producers need long-term commitment to establish this grass. Once established, however, benefits include resistant and resilient haying or grazing systems.

To maximize its potential for production with desirable forage quality, N fertilization and harvest management are important considerations. Previous studies have evaluated the effects of fertilizer and multiple cuttings on EG production and forage quality. However, responses of EG biomass and quality to N supply and harvest interval varied from location to location and from year to year. For example, N fertilization in New York did not affect EG forage quality, but N rate affected EG biomass and forage quality in Missouri. Identifying the optimal N rate and harvest timing adjusted by year and location are important to maximize profitability and to avoid excessive nutrients leaching into groundwater or lost to streams in runoff. Unlike common commercial crops, EG can have relatively high production under marginal conditions (e.g. wet, lack of nutrients, and drought). Its rhizomatous root system efficiently extracts water and nutrients, and provides good soil protection, as well as contributing significant carbon pools in the soil.

Despite the numerous benefits of this grass, many farmer in rural areas do not have sufficient information on the benefits of EG as an alternative forage crop. This work will enumerate its benefits and provide better guidance for establishment and fertilizer application for maintaining productive, resistant, and resilient forage and hay production.

EG is a native perennial grass that ranges over much of the eastern, southern and southeastern U.S. This grass produces high quality forage and high yields on land considered marginal due to excess moisture. To develop EG as a potential alternative crop for sustainable forage production on marginal and/or less productive lands associated with flood and nutrient depletion, the proposed project consists of evaluation of a diverse set of accessions in a research nursery; measuring critical plant parameters and environmental factors to characterize each; and selecting the best accession for different types of sites (flood prone and low fertility).

Measurements will be taken on agricultural experiment station plots and on two farmers' fields with different treatments including applied fertilizer and harvest interval. The experiment will be laid out as a split block randomized complete block design with three replications. Results of this project will lead to optimized management of these accessions, esp. applied fertilizer, to minimize cost, maximize profit return, and avoid negative environmental impacts (esp. soil and water qualities), and maximize forage quality. Information derived from these sites will be used to develop process-based modeling of crop growth. This model is an effective way of representing how EG accession, environment, and cropping management interactions affect forage production. This will increase the accuracy of crop productivity estimates and improve planning adaptation strategies to reduce risks and uncertainties about economic returns generated from planting EG. The developed forage model system will be used for decision-making, farm planning and educating farmers or ranchers about potential benefits of EG establishment. Education effort for farmers or ranchers will be carried out using field demonstrations and through news publications directed towards agricultural producers. Farmers will be offered a chance to visit the research plot areas, with an annual field day and talks by the researchers to discuss the economic and environmental benefits and remaining challenge of an EG production system.

The following specific objectives will be pursued:

• Identification of morphological and physiological characteristics of EG for its sustainable, high biomass production for high quality forage;
• Evaluation of effects of harvest intervals and nitrogen rate on forage yield potential and quality and soil health on marginal areas where stresses such as low supply of plant nutrients and flooding often limits forage production;
• Development of models for the assessment of current and future range management scenarios.