- Agronomic: annual ryegrass, grass (misc. annual), grass (misc. perennial), peas (field, cowpeas), sorghum sudangrass
- Animals: bovine, sheep
- Animal Production: feed/forage, grazing management, manure management, pasture fertility, rangeland/pasture management
- Crop Production: nutrient management
- Production Systems: holistic management
Cow-calf and stocker cattle operations often face a shortage of grazable forage on pastures during summer, early fall and winter. To provide access to high quality, grazable, and sustainable forage, we plan to study the feasibility of an integrated system using sub-surface poultry litter application on pasture in tandem with planting a mix of summer annuals and legumes to increase both the efficiency and level of nutrient application. This will enhance both forage quality and quantity for grazing. In addition to spring-planted annuals we also wish to investigate the potential for fall planting winter annuals for winter and early spring grazing. Those plantings will also benefit from the spring litter application given the slow release nature of nutrients with litter. In comparison to conventional perennial pasture forage species, our least intensive system, these annuals are expected in increase nutrient uptake from the soil and thereby extend the grazing season, while keeping nutrients below the soil surface. With litter applied sub-surface, we can expect to avoid nutrient runoff, increase water infiltration and soil water-holding capacity given greater root growth and eventual increase in soil organic matter.
Experiments will be conducted at research centers and four cooperating farms where crops are selected based on landscape suitability. Variation in crop mix options and animal type will allow comparison of profitability and income risk. To assist with this task, a cattle decision support system exists that can: 1. model forage growth and cattle her nutrition needs on a monthly basis; 2. calculate greenhouse gas emissions of varying production practices; and 3. perform what-if analyses concerning key economic and environmental performance indicators. However, it is currently not equipped to analyze detailed fertilizer application and annual sod seeding practices.
Therefore, we will evaluate innovative agro-grasslands management approaches by: 1. examining profitability and risks of added forage production using organic litter to extend the grazing season which is expected to lower hay feeding and attendant fuel use; 2. determining the feasibility of using innovative equipment to incorporate both litter and planting crops in a single equipment pass to allow greater use of nutrient rich manures on pastures; 3. matching crop needs to spatially variable landscape attributes to sustainably manage yield potential, soil moisture, and net GHG emissions while increasing beef output that can be marketed as grass-fed and/organic; 4. comparing forage soybean and cowpea sown in conjunction with brown mid-rib sorghum-sudan grass and a ryegrass/cereal rye/wheat and legume mix as winter annuals for livestock grazing (cows, stocker cattle and sheep); and 5. calibrating and modifying the existing cattle DSS tool with producer input to enhance user-friendliness.
Adoption of more annuals and custom, sub-surface applied litter could impact many producers of all operation sizes throughout agro-grasslands in the Southern humid region of the U.S. where approximately one third of all agricultural land is dedicated to pasture and hay. Outreach activities will share successes, pitfalls, and bottlenecks observed across varying degrees of pasture use intensity proposed in this holistic research system.
Project objectives from proposal:
- To determine the impact of summer annuals on grazing days and animal weight gain in bermudagrass-dominated systems.
- Assess forage production potential of different summer annuals and winter annuals under sod-seeded conditions without grazing.
- Measure changes in soil health across holistic pasture management systems varying in grazing intensity and soil fertility amendment practices under both research and farm conditions.
- Conduct producer field trials to assess field performance of sub-surface poultry litter application equipment that is modified to plant at the same time.
- Calibrate and modify existing decision support software to provide greater planning support for cattle operations using producer feedback about needed modifications to improve user-friendliness.