A lot of those ranchers are learning along the way that their best hayfields don’t necessarily make the best pastures. Historically, hayfields in the U.S. have fallen into three broad categories: alfalfa, N-fertilized grass monocultures or grass-legume mixtures.

Of these three options, only the grass-legume mixtures transition easily into pasture.

What are the fundamental differences between hayfields and pastures? Let’s start out by thinking about harvest method. One of the laws of nature is as individual plants get larger, there are fewer plants per acre. Whether we’re talking about a pine forest, cornfield or pasture, this universal law applies.

Hayfields tend to have a lower plant density than do properly managed pastures. Because we let the plants in a hayfield get larger and more mature on average than we do in a pasture, there will always be fewer plants per square foot in a hayfield.


This leads to less plant litter cover in hayfields compared to pasture. Exposed soil weakens the water cycle, so we want to keep the soil covered as much as possible.


One of the main complaints we hear about grass-legume mixtures grown for hay is the variability in maturity and inconsistency in quality. That is only a problem with mechanical harvest.

When we make hay, we like to have plants of uniform growth stage to create consistent quality in the hay crop. This is one of the big advantages of alfalfa and N-fertilized grass. In contrast, we like to see a variation in the maturity of forage species in a pasture because it spreads out the quality grazing opportunity.

When hay is harvested from a field and fed somewhere else, there is a mining effect on the soil. In typical hay production, more than 80 percent of the minerals contained in the above-ground portion of the plant are physically removed from that field.

With grazing, more than 90 percent of the minerals contained in the grazed portion of the plants are returned to the field as dung and urine. Many hayfields have chronic mineral deficiencies whereas pastures can have much more favorable micro-mineral levels.

The three challenges we need to tackle when converting hayfields to pasture are increasing biodiversity, increasing ground cover as both living plants and litter, and getting the soil back to a well-mineralized status.

Just the act of changing from mechanical harvest to grazing will start the changes we need, but sometimes we might want to accelerate the process a little.

We can address both the bare ground and biodiversity issues by interseeding additional species into our former hayfields.

In the case of alfalfa-dominant fields, we want to increase the amount of grass in the pasture to increase soil stability and reduce bloat potential of alfalfa. We have our best success seeding cool-season grasses into alfalfa with a late-summer seeding.

In the spring, alfalfa really wants to grow, so it is very competitive and it can be difficult to get new grass seedlings started under a heavy alfalfa canopy.

In late summer, alfalfa is already thinking about going dormant, so it becomes less competitive while the new grasses want to grow in late summer and early fall, so they become more aggressive.

Start the grass interseeding process by severely grazing the alfalfa in August. Grazing at a high stock density will usually get the cattle to also consume most of the weeds that are out there if you have a weed issue in the alfalfa field.

Put several grass species in the seed mix based on what generally does well in your area. Through the Northeast, Midwest and into the irrigated West, we recommend a mix containing orchardgrass, endophyte-free tall fescue or festulolium and timothy.

The 1973 - 2013 comparison adjusted for inflation

Where they are adapted, we will also throw in meadow bromegrass, meadow fescue and perennial ryegrass.

For grass hayfields that have been heavily fertilized with N in the past, our concern is adding legumes into the pasture mix. In the central to northern region, the mix usually contains red, white and alsike clover.

Depending on particular local adaptation, we may also include birdsfoot trefoil, strawberry clover or annual lespedeza. We generally seed these legumes in late winter or very early spring, either by broadcast frost seeding or with a no-till drill.

The drill is more reliable if used properly but also much more expensive than broadcast seeding.

In more southern climes, where the base grass might be bermuda or bahia, we tend to work more with the winter annual legumes like crimson, arrowleaf, ball or berseem clover along with the vetches and peas. Heat-tolerant white clovers can also work in these summer grasses in parts of the South.

The keys to establishing and maintaining strong legume stands in pastures are in the timing of the grazing and duration of recovery period.

Carefully managing grazing to suppress competing growth from the existing forage crop in the first four to six weeks following seeding is critical to establishment. Allowing enough recovery so the legumes reach a blooming stage before the next grazing event will help ensure their survival.

Most legumes will do a good job of maintaining themselves over the long term if allowed to mature and set seed every two to three years. Depending on species, the required recovery period is from 50 to 70 days. Longer recovery periods generally give better results.

Longer recovery periods also will leave more dead plant litter on the soil surface to help with water infiltration and reducing the evaporative water loss from the soil. Always remember the more you grow above-ground, the more you can afford to waste some grass just to create better soil litter.

Our final need is re-mineralizing the soil. Just feeding your livestock either a complete mineral mix or using a cafeteria free-choice program will put a full range of micro-minerals back out on the soil simply because most of those supplemental minerals cattle are consuming are coming right on out of the back end of them and enriching the soil.

You might still want to take some soil and plant samples to assess the mineral status of the recovering hayfield. If there are signs of acute mineral deficiencies, you may want to apply the deficient micro-minerals directly to the soil.

Because of the very small amounts of micros we may need to apply, getting a uniform spread can be a real challenge. Sometimes having a little patience and letting the cattle spread them for you is the optimal approach.  end mark


What made economic sense 30 or 40 years ago just doesn’t work today because input costs have increased at four to five times more than the value of product.

Even with the record-high cattle prices of 2014, in inflation-adjusted dollars beef is worth only about two-thirds of what it was in 1973, while our most common inputs have far outraced the general rate of inflation.  end mark 

PHOTO 1: With equipment and other input costs steadily rising, more producers are converting from mechanical hay harvest to livestock-grazing harvest. However, not every hay field makes a great pasture.

PHOTO 2:  Pastures generally benefit from interseeded legumes such as clover, but good establishment and survival depend upon carefully managed grazing. Photos courtesy of Dawn Gerrish.

Jim Gerrish