As a result of last summer's drought, I am getting questions about pasture and hayfield renovation. What can be done to thicken up forage stands that have been thinned out?
The first step is to evaluate the forage stand to determine renovation options. Use a one-foot square as a tool to help quantify the stand density. Take 10 to 15 random one-foot square samples per hayfield or pasture to provide an estimate of the average stand condition. If the stand is a grass or grass legume pasture or hayfield evaluate the stand based on the percentage of bare or open soil plus the presence of legumes if the stand is a mixed grass/legume stand. There should be less than 10% open or bare soil. There should be 2 legume plants per square foot in a grass/legume mixture. If these conditions are not met, then partial renovation should be considered. In the case of an alfalfa hay stand, there should be 10 to 15 plants per square foot in a second year stand and at least 5 to 6 plants per square foot in a 3rd year and older stand.
A partial renovation can be defined as adding forage seed to an already existing forage stand with the goal of increasing the stand density of desirable forage plants. No-till seeding is the typical method used for partial stand renovation; however March often offers an opportunity to utilize frost seeding as a renovation method if certain conditions are met. Frost seeding involves broadcasting seed over a pasture or hayfield area and letting the natural freeze/thaw cycles of late winter and early spring help to move the seed into good contact with the soil.
A basic requirement for frost seeding success is to make sure that the sod cover has been opened up, so that some bare soil is exposed. Last year's drought may have caused the loss of enough desirable plants that there is sufficient bare or open soil without any additional preparation.
Another twist to frost seeding that sheep producers can use to their advantage is to combine frost seeding with hoof action. Under this seeding scenario, let your sheep begin to graze the paddock or hayfield that is to be frost seeded. Let the sheep graze down the forage, scuff up the soil and open up bare areas in the sod. At this point, broadcast the forage seed across the paddock. Keep the sheep in the paddock another couple of days and let them continue to graze and trample or hoof in the seed. This method seems to work well with sheep because they don't trample in the seed too deep as could happen with cattle.
In general, legumes work better for frost seeding as compared to grasses. Clovers are most commonly used in partial renovation situations to improve grass pastures or hayfields. Broadcast rates for frost seeding of clover is 6 to 8 lbs. /acre for red clover, 2-3 lbs. /acre for white clover and 2-4 lbs. /acre for alsike clover.
I have been asked the question about renovating an alfalfa stand. Due to an autotoxicity condition that involves the release of a chemical from the roots and plant parts of established alfalfa plants, new alfalfa seedlings do not have a good survival rate, so it is not economically viable to thicken up an old alfalfa stand with more alfalfa seed. It is possible however to convert an alfalfa stand to an alfalfa grass stand by no-tilling a grass into the older alfalfa stand. Good candidates for this type of renovation include orchardgrass and festulolium grass. Festulolium is a grass species resulting from the cross of a meadow fescue with an annual or perennial ryegrass or a tall fescue with an annual or perennial ryegrass. The festulolium combines some of the desirable forage quality and quick establishment of a ryegrass with some of the hardiness traits of a fescue grass.
A final important point regarding pasture or hayfield renovation is soil fertility. To allow that new forage seeding to have a chance to thrive and be productive the soil should have the proper soil pH and nutrient level. Critical or minimum levels include a pH of at least 6.3 for grasses, 6.5 for clovers and 6.8 for alfalfa. Soil phosphorus should be at 25 parts per million (ppm) or 50 lbs. /acre and soil potassium should generally be around 120 to 125 ppm or 240 to 250 lbs. /acre. For more information about pasture or hayfield renovation contact County Extension office, or review the recent "Pastures for Profit" Grazing School presentations you'll find under this link.
Source: Rory Lewandowski, Extension Educator, Wayne County