Renovating Broom Sedge Infested Grasslands
Margit Kaltenekker
Agriculture
Extension Agent
Many callers ask about restoring productivity of our grasslands in Douglas County. Many pastures and hay grounds are infested with ‘Broom sedge’ (Andropogon virginicus), also known as ‘Broom sedge Bluestem’ or ‘Poverty Grass’ is not a true sedge, but a warm season - native grass resembling Little Bluestem (Schizycharium scoparium) with its red, fluffy seed heads. Broom sedge becomes a problem in fields or pastures that are frequently hayed below 3 – 4 inches, or over-grazed, but not routinely fertilized. Poorly managed pastures and hayfields – have bare soil, leaving them vulnerable to weeds of all kinds. Broom sedge thrives in “poor”, low pH (acidic) and low phosphorous soils which is why it is commonly called ‘Poverty Grass’. Highly un-palatable to livestock, Broom sedge takes over pastures as they selectively graze around it;– it goes to seed! Its control is a matter of soil fertility, lime, and grazing management and possibly summer burning or glyphosate herbicide.
Sustained productivity of lush grass pastures demands regular fertility and intensive grazing management, (or MIG). By supporting the health and growth of the grasses you wish to favor, the noxious weeds will decrease over time with proper management.In some cases, reseeding pastures is another way to increase production of the grasses you wish to favor, but a lot can be done with proper management alone.
Soil test and adjust fertility. Follow the K-State recommendations for fertilizing your pastures. Broom sedge favors soils depleted in phosphorous and lime. Boosting pH and soil fertility will strengthen the stands of the warm and cool season grasses giving them a chance to outcompete some of the Broom sedge, but it takes at least 1-2 years for lime to dissolve in the soil. If you choose to follow the conventional, chemical fertility approach you will need to follow through with a fertility program for a few years prior to seeing noticeable change in the grassland.
A lower cost ‘biological approach’ is equally effective. Reserves of soil microbial populations responsible for solubilizing soil mineral nutrients are depleted as healthy plant growth diminishes. A good rule of thumb regarding plants’ top: root ratio is: ‘As Above, So below’. If you don’t have lush thick forages above ground, roots are equally depleted below ground. Lacking leaf cover, (think: Photosynthesis Solar Collectors) deprives soil microbes from receiving carbohydrate exudates (sugars) they depend on!
Manage grazing and clipping to selectively favor palatable forages. Using temporary fencing, with smaller paddocks, allows you to move cattle and livestock over ground within a shorter period (1 -2 days). Livestock select the grasses they desire. Following the grazing period, allow for a longer rest period (21-30 days) for those grasses to recover. Clip the Broom sedge and undesirable weeds after grazing. Manure and urine deposits will recycle 85-90% of those nutrients consumed by livestock. In winter ‘bale graze’ hay over the Broom sedge infested pastures. Each ton of hay contains roughly 50 lbs nitrogen, 15 lb phosphorous and 60 lbs potassium. This is a much slower way of applying nutrients than commercial fertilizers or broiler litter, but biological activity from animal excrements restarts healthy nutrient cycling.
Consider a late summer burn in August to favor the cool season grasses ahead of the fall grazing season. Burn treatment could be followed by fertility applications and/or reseeding with a no till drill, available for rent through the Douglas County Conservation District. Reseeding pastures is best after a summer burn or mass glyphosate application mid-summer. Reseeding pastures gives you an opportunity to consider adding legumes to your pasture mix which would aid with nitrogen fixation.
Please check out more grazing resources on our website:
https://www.douglas.k-state.edu/crops-livestock/pasturemanagement/pasture.html
