- Agronomic: general hay and forage crops
- Additional Plants: native plants
- Crop Production: application rate management, foliar feeding, nutrient cycling
- Production Systems: holistic management
Native tall-grass prairies in the United States were once found on about 400 million acres. Now, less than 3% of their original expanse exists. Farming, loss of natural disturbances (fire and grazing), and introduced exotic plant species have contributed to this reduction. Invasive exotic plants, which have often been introduced purposefully, out-compete native species and reduce native diversity and productivity. Native species abundance and productivity can be increased when released from competition by human intervention and/or if natural processes, such as fire, are reintroduced to the ecosystem.
In this study, two South Dakota field locations containing mixed native and non-native aggressive species will be treated with fire, chemical, and/or nitrogen applications at various times during critical growth stages of the species of interest in order to reduce the presence and productivity of invasive species and stimulate native species. Native species in field plots include big bluestem (Andropogon gerardii), sideoats and blue grama (Bouteloua curtipendula and B. gracilis) whereas the predominant invasive species includes smooth brome (Bromus inermis) and Kentucky bluegrass (Poa pratensis). A greenhouse project that complements the field study examines the influence of shoot and root competition on establishment and growth among these native and invasive species. Leaf area, root and shoot biomass, and perennating structure formation will be evaluated by species.
For land managers and producers, relatively inexpensive steps can be taken to enhance the native species component of pasturelands with the use of prescribed burns, appropriate timing of herbicide application, and modest applications of fertilizer. These steps would sustain and increase native grass species biomass, increase forage production, improve wildlife habitat, and decrease the need for weed management in surrounding croplands. The objective of this study was to evaluate the use of fire, herbicide and nitrogen applications to reduce non-native cool-season grass species competition and biomass while increasing native warm-season grass species biomass at a low cost and straightforward for land managers and producers as a step towards restoration of pasture or infested grasslands.
Short term outcomes: Identify and quantify grass species located at two sites prior to application of treatments, apply spring and fall treatments and follow the outcomes of the treatments through the following growing season(s), determine vegetative growth rates of native vs invasive species alone and in combination in field and in greenhouse studies, and compare root and shoot growth rates of species of interest alone and in combination in the greenhouse under warm and cool temperatures.
Intermediate outcomes: Examine the treatment effects on competition and determine treatments or treatment combinations that would be effective management tools to reduce invasive cool-season grasses, and improve native grass composition. Inform producers about the effective treatments through meetings, field days, and publications.
Long term outcome: Producers and land managers have affordable management methods other than large scale herbicide applications to improve pasture conditions by reducing introduced invasive grass and encourage more native grass populations for improved forage and aesthetic quality.