Improving Spring Pastures for Dairies

Published on Thu, 02/16/2023 - 6:14pm

Improving Spring Pastures for Dairies.

 By Heather Smith Thomas.

 Fresh pasture is often the best forage for dairy cows and heifers, but needs to be lush and green with optimum nutrient levels.  Good pastures may not stay tip-top over several seasons, and periodically may need attention to improve them.

Glenn Shewmaker, Emeritus Professor and Forage Specialist, University of Idaho says the first thing to do is take a close look at the pasture, assess its ecological condition and decide whether it needs some inter-seeding or a complete renovation, and whether renovating will be economical.  “It is important to know whether we really need to do something to improve this pasture.  There can be reasons to do it—such as to change the pasture management, put in better types of forage species that are more suited to your purposes, or that might last longer than the last time it was seeded,” he says.

Luke Wilson, Market Development Manager for Barenbrug USA says that when assessing a pasture to evaluate when or what might need to be done to improve it, we should look at plant stands and see how many plants per square foot are still there.  “About 12 to 15 plants per square foot is a good number to have. When there are less than that, we need to increase the pasture productivity by adding more plants,” he says.
If we are not happy with the production, or don’t feel that the existing plants are growing optimally, it also pays to do a soil test.  “Look at your soils, because they may be the problem rather than needing to add more species or inter-seeding.  There might be something you need to correct in terms of soil fertility,” Wilson says. “As seed salesmen, we always like to sell farmers more seed, but more seed won’t provide the solution if the soil is the problem.”

Shewmaker says you need to know the soil nutrient status, to know if it will support new plants.  “If you don’t have proper soil fertility, this is your opportunity to work something into the soil.  There may be areas of the pasture with low pH (acid soils) and you could work some lime in, if you want to add legumes,” says Shewmaker.  

“Then you need to figure out which species you need, either to extend grazing or provide more production for more cows. There are ways to add to an existing pasture without plowing it up.  We’ve done studies on inter-seeding—which means you don’t till.  It’s like a no-till or minimum-till seeding into an existing stand to fill in the blank spaces and add new species.” This works nicely if there are places in a pasture that have been overused or trampled out.

“Inter-seeding is the best method in many ways, though it’s harder to establish new plants.  You don’t lose the whole year of grazing, however.  You’d only lose half the year.  You have to protect the new plants from grazing for a while so cattle don’t pull up the new seeding, pulling all the roots out of the ground,” Shewmaker says.

If you need to graze the pasture, you could fence off the newly seeded areas with a hot wire, to keep cattle out except for a short period of time.  “This would give you control of the grazing so you could monitor it closely,” says Shewmaker.

“We’ve done studies comparing different methods, to try to get a successful inter-seeding.  One option is to just graze it very close--the fall before--to remove all the forage you can.  This would be one of the few times we recommend heavy grazing pressure.  This stresses the plants, to reduce their growth the next spring, before you inter-seed, and reduces competition for the new plants,” he says.

“Another thing we’ve tried, to retard the older plants, is applying a half rate or low rate of glyphosate (Roundup) to knock them back a little.  The idea is to retard those plants but not kill them.  This is more effective than just trying to graze them,” he says.

“We found that timing is critical, in terms of when you’ll seed it afterward.  It looks at first like you’ve killed everything, but pretty quick it greens back up.  You have to do it at the right time, in conjunction with your new seeding,” says Shewmaker.  

Joe Brummer (Colorado State University) led these studies.  “We did that this at Kimberly, Idaho and Fort Collins, Colorado, and at Klamath, Oregon.  We applied glyphosate at a rate of 2 quarts per acre after the grass had greened up in late April/early May.  Then 2 weeks later we drilled the seed.  That was the most effective way of inter-seeding, especially for legumes.  We tried alfalfa, white clover, birdsfoot trefoil, sanfoin and red clover.  This was the most effective way to do it, but risk of poor establishment is higher, compared to tillage,” says Shewmaker.

This method is less expensive than plowing it up.  “Adding a legume can really extend a pasture.  Everyone has grass in May and June, but in July and August you start to run short when cool season grasses slow their growth.  The best way to fill in that mid-summer slump is with a legume.  It keeps growing, and adds nitrogen to the soil, reducing the fertilizer bill, and provides a well-balanced diet for cattle with a high quality pasture.  The only downside is bloat risk, but you can seed in a non-bloating legume like birdsfoot trefoil as part of it.  You can keep the grass component as the majority, but add enough legume that you don’t need any nitrogen fertilizer—and that saves money,” he says.  This would be a way to improve the entire pasture system.

Producers should talk with their local extension people for advice on specific plants and timing, to fit the region and climate.  “Some of the little things make an important difference; local advice and seeding guides would be most appropriate.”  Timing of planting would be different in Texas than it would be in Idaho or Montana.

“Equipment is also important, depending on whether it will be full tillage or inter-seeding.  If you want to do inter-seeding, a no-till drill is essential.  You can broadcast seed; we’ve done it, and sometimes it works very well but most of the time it does not.  It’s difficult to get good seed-to-soil contact in an existing stand of grass, even with a good no-till drill.  We’ve found that it’s fairly easy to open up the drill and get the seed down into the ground, but the biggest challenge is good seed coverage and packing the ground behind the drill,” Shewmaker explains.

Trampling it into the soil with livestock can work, certain times of year, depending on soil moisture.  “Pivot irrigation helps make that work, where you can keep the ground wet with just the right amount of moisture.  It is always a compromise, when inter-seeding, and difficult to predict success, but the benefits can be good.  Basically all you are out is the cost of the seed if you don’t get a good take on it, but there will almost always be some new seedlings come up, especially in open places where there isn’t much competition from other plants,” says Shewmaker.

“The easiest way to improve a pasture, economically, would be frost seeding for introducing legumes into that stand,” says Wilson.  “In some climates you might be able to frost seed, or you could inter-seed clovers or alfalfa to add a legume.  Frost seeding is easiest because it doesn’t take many pounds of seed for clovers (about 1 to 2 pounds for white clovers and 4 to 5 pounds for red).  You can broadcast that seed in the winter months, right before the spring thaw.”

The weight of the clover seed (which is heavier than grass seed) enables it to work its way into the ground during the honeycombing effect when the ground thaws.  “This provides the necessary seed-to-soil contact.  I don’t recommend trying to do this with grasses because grass seed isn’t heavy enough to achieve seed-to-soil contact and the seed is more likely to blow away or be eaten by birds,” says Wilson.

“If you want to increase the grass content of a pasture, you probably need to use a drill.  This way you can ensure proper seed-to-soil contact.  If you are dealing with dairy pastures, keeping in mind that every region is different, probably one of the better grasses to add to existing stands would be perennial ryegrass because it establishes quickly and can be growing sooner than some other species.”  The high sugar content of ryegrass is also a plus; it is excellent for a dairy ration, and can be grazed early in the spring.

“When you inter-seed a grass into an existing stand, one of the worst things you can do is put it in and then not graze it,” Wilson explains.  You don’t want to overgraze the new plants, but you do need to lightly graze that pasture; otherwise the established grasses that are already there will get ahead of the new seedlings and canopy over them.  The new grasses won’t do well in the shade; they need sunlight.

“By contrast, legumes like clover and alfalfa can grow nicely in the shade—much better than grasses.  When you’ve inter-seeded grasses you need to go through that pasture a few times with cattle to do light grazing, to keep that canopy open, allowing the new seedlings exposure to sunlight,” says Wilson.

You don’t want to over-protect it by not grazing or harvesting.  “Even when seeding a new hayfield using a nurse crop, you want to get that nurse crop off quickly so it won’t shade out the new seeding.”

If you didn’t have a chance to evaluate the pasture in the fall, to assess the plant stand, and get into the next growing season and realize a need for more productivity, there are still some things you can do.  “It’s not too late to go out there and drill more seed into it, once the spring grass starts.  Depending on the region, it might be a situation where halfway through the spring if you don’t like the production, you could look at putting in a warm season grass to add production to that pasture,” says Wilson.

This can be a delicate situation in a dairy, because of the quality difference between cool season grasses and warm season grasses (which have lower nutrient quality).  “If you are in area that gets hot and humid and the nights don’t cool off, it may pay to add some warm-season grasses.  In the southern U.S. the ryegrass and any other cool season grasses will shut down and stop growing; they go dormant in hot weather and you’ll lose productivity.  If it’s halfway through the spring season you can’t inter-seed perennial ryegrass and expect to get a lot of production,” he says.

Instead, you might want to look at what else you could add into the pasture to get more production through the summer months, and then in the fall evaluate the stand and add the cool season grasses if you want to.
Climate and region can make a difference in some of your options and best choices.  “In the forage world, it’s never one size fits all.  There are different scenarios for different areas,” Wilson says.  It may pay to get advice from a forage expert in your region who could help guide you in decisions regarding what to plant in your situation.

“I always stress importance of having diversity in the mix for a grazing dairy pasture.  Don’t put all your eggs in one basket.  Having a varied mix of grasses and legumes is most beneficial and you could even incorporate some brassicas if you need a short-term solution,” he says.   There are more total nutrients and a better balanced diet for the cattle when you have more than one species in your pasture.  It’s better for the plants and their productivity as well.

“You get a symbiotic relationship between legumes and grasses; they benefit each other.  It helps with the plants and the animals to have some diversity in the pasture.”

Proper management is just as important as the plant mix and stand density.  “Overgrazing is one of the hardest things on a pasture.  If you can leave a good stubble height you will get so much more production because it regrows more quickly.  If you overgraze, you are hurting the next cutting or the next graze rotation,” Wilson says.

“Brassicas can be very nutritious and good forages for a short-term solution because they are annuals and grow quickly.  Annuals are always helpful for short-term pasture improvement; annual ryegrass and brassicas will give you the most feed in the shortest amount of growing time.  They can provide feed for the cattle while you evaluate what you need to do for a long-term solution or more permanent pasture,” Wilson says.

“Maybe you want a total renovation but if you can’t get that pasture up and going right now, annuals will be an interim solution for this year.  If you are wanting to stay on the same rotation and not break it up, however, you can just add more perennial grasses and legumes to the existing pasture.”

There are many options, depending on your goals and situation.  “Best case scenario is to have evaluated your stand last fall, to know what you will have in the spring, looking at the number of plants per square foot, and determining what your goals are.  If you want to keep that stand you might simply add legumes, but for a short-term solution you could go with some annuals that could be added halfway through the spring growing season.  You could add cool season legume later and maybe just add a warm season grass for right now, depending on your region.  Whenever you seed, just do a light grazing as those new plants are coming in—not enough to damage them but enough to open up the canopy of older plants,” Wilson says.