Location: Forage and Livestock Production Research2013 Annual Report
1a. Objectives (from AD-416):
The overall goal of this project is to identify improved forage production techniques that will contribute to decreased costs of livestock production and increased income on limited-resource farms. The purpose is to develop low-input forage production techniques that are appropriate for resource-poor producers, and that will increase livestock carrying-capacity, improve early- and late-season forage production and reduce or eliminate expenditures for off-farm feed supplies. This purpose will be met by evaluating combinations of forages grown in mixtures or sequences, and by developing low-input management methods that will enable their use as a productive and persistent complement to, or replacement for, unimproved or degraded pasture. Specifically, we will focus on the following objectives: Objective 1. Identify appropriate forage species and develop low-input techniques for increasing forage production and extending the grazing season on degraded or unimproved pastures to increase year-round availability of homegrown forage and provide economically and environmentally sustainable forage production systems for under-served, resource-limited livestock producers. Sub-objective 1A. Assess the productivity and persistence of non-traditional warm- and cool-season grass and legume mixtures for utilization under grazing. Sub-objective 1B. Identify the most effective low-input establishment techniques (no-till drilling, broadcasting or self-seeding) for cool- and warm-season grass and legume forages established in mixtures with existing, unimproved pastures of native species or bermudagrass. Objective 2. Determine the cause(s) of poor establishment of cool-season grasses and legumes following self-seeding or over seeding into established pastures, such as loss of seed quality, hydration/dehydration cycles, temperature or moisture stress, and adverse soil characteristics such as compaction or plant litter. Objective 3. Determine the usefulness of accumulated temperature (degree days) as an aid to timing of pasture management operations such as fertilizer application and harvesting, in order to minimize competition in cool- and warm-season grass mixtures during seasonal transitions.
1b. Approach (from AD-416):
Replicated experiments will be undertaken in controlled-environment or in small-plot field trials to measure management effects on establishment, production and persistence of cool-season forages grown in mixtures with warm-season pasture. Processes of regeneration and persistence in cool-season grasses and legumes established by minimal tillage in sequence with unimproved warm-season pasture will be studied. Low-input methods of sowing that will improve the efficacy and predictability of establishment of forage grasses and legumes and that allow improved early-season production from cool-season forages will be evaluated. Indicators of the onset and termination of forage growth will be determined to facilitate management and to minimize or eliminate interference between cool- and warm-season forages. Results from the project will identify forage management systems adapted to low-input farms and forage mixtures that enhance and extend the productive grazing period of pastures.
3. Progress Report:
This is the final report for the project which was terminated in December 2012 and replaced by 6218-21610-001-00D. Efforts to resolve the widespread problem of feed shortage for grazing livestock in the southern Great Plains have centered on production of cool-season grasses. This project confirmed earlier work showing that, because no-till seeding avoids destruction of the existing warm-season pasture, the year-round forage yield can be increased by no-till compared with conventional planting of cool-season forages. However, perennial cool-season grasses lacked persistence and over a 3- to 4-year life did not produce enough forage to justify the cost of planting. Summer-dormant tall fescues showed minimal improvement in persistence and much lower productivity, compared with summer-active fescue lines. Broadcast sowing is an alternative low-input seeding method that may be more accessible to small producers than no-till drilling, which requires specialized equipment. The project showed that, although broadcast seeding was less effective than drilling for stand establishment, there was no difference in harvested yield in the spring between sowing methods. Broadcast seeding is attractive to small farmers and will increase the number of those attempting to overseed for production of cool-season forage. No-till sowing is usually made into soils that are more compacted than conventionally cultivated seedbeds, and concern has been expressed that this affects relative performance of grass varieties. The project demonstrated that, although increased soil compaction slowed seedling growth and development, the cultivar rankings determined under conventional cultivation and sowing are likely to be valid in more-compacted soils that are characteristic of no-till sowing conditions. The project showed that it is essential that warm-season pasture be preserved in order to maximize year-round forage production, but the assumption that yield effects of combining these warm- and cool-season grasses are 100% additive, through complementary use of different seasonal growing conditions, is not valid. Each additional 1 kg of cool-season grass harvested resulted in an average net benefit of only 0.43 kg in total herbage yield, as a result of suppression of warm-season grasses by cool-season grass. This is an important observation that shows that economic evaluation of overseeding cool-season grasses into existing warm-season pasture must consider not only the value of cool-season forage produced, but also the cost of warm-season production lost by overseeding. Nitrogen fertilizer is a necessary input for cool-season grass production, but it requires careful management if it is to be used cost-effectively. The efficiency of nitrogen use in cool-season grasses was greatest and most consistent with early spring application of nitrogen. Fall application of nitrogen was not essential for establishment of cool-season grasses, and residual effects of a fall application on spring grass yields were small. Elimination of fall application will allow small producers to reduce the cost of nitrogen use by 25-33% of current recommendations for cool-season grasses.