Healthy soils limit pasture weeds
One way to control pasture weeds is to ensure they never have the opportunity to grow.
Healthy soil can deter weeds from growing, says University of Missouri weed scientist Kevin Bradley. In a recent Successful Farming article, Bradley said that each one-unit increase in soil pH resulted in 4,100 fewer total weeds per acre. As soil phosphorus (P) and potassium (K) levels improve, weeds also decrease.
Poor pasture soil health is common, though. Bradley’s research found that 80% of pasture soils tested were low to very low in phosphorus.
“Properly functioning soils capture, store, and redistribute water; grow plants; and cycle plant nutrients,” according to the USDA’s Grazing Management and Soil Health publication. “To improve pasture health, land managers must manage for soil health. As the soil improves, forage production will increase and fertility needs will decrease, leading to increased profits.”
Healthy soil, along with proper grazing management, helps maintain plant roots and healthy stands of forage. When poor soil or excessive grazing depletes desired plant growth, bare spots may appear. Bare ground opens the door to an increase in undesirable plant and weed growth, as well as an increase in water and wind erosion.
“Weeds that can germinate quickly can increase dramatically on depleted land. The land becomes less fertile and better adapted to weeds than to desirable forages—increasing drought severity and frequency. Managing pastures with soil health in mind will help improve aggregate structure which will improve infiltration. Increased organic matter improves the soil’s ability to store water.”
Build healthy soil. Graze half, leave half or more!
Watch the video: After you move cattle to a new paddock, check the consistency of the manure and the plant residuals to determine if cattle are getting the proper nutrition while leaving adequate forage behind for regrowth. Logan Karcher, director of producer programs with Illinois Grazing Lands Coalition, illustrates what to look for in a manure pat, as well as how to evaluate residual plant materials after a move. Plant residual dry matter breaks down and feeds soil biology. It provides soil cover which helps keep the soil cool and moist.
Learn More
University of Illinois Extension provides a list of soil labs certified by the Agricultural Laboratory Testing Association.
University of Missouri Extension provides a complete guide to sampling soil pastures, including where to sample, how to pull a soil core, and submitting your soil for testing.
University of Iowa Extension provides a guide to fertilizing pastures, including nitrogen, phosphorus and potassium recommendations for grass and mixed legume-grass pastures.
References
Fertilizing Pasture, Iowa Extension, Antonio P. Mallarino, professor of agronomy and Extension specialist, Stephen K. Barnhart, and John E. Sawyer. Revised March 2023.
Soil Sampling Pastures, Missouri Extension, John Lory and Steve Cromley
Division of Plant Sciences and Commercial Agriculture ProgramSoil Testing, Illinois Extension, Chris Enroth
How to Control Pasture Weeds and Improve Forage Quality, Successful Farming, Gene Johnston