- May 1, 2006
As the snow recedes and green starts to reappear in your pastures, do you see bare spots, or areas with too many weeds? Has your grass production diminished to the point that what used to be your main source of forage now is only a playground? Are there poisonous weeds in your pasture? Has the clover taken over, limiting grass production or making the pasture too nutrient-dense for your easy keepers? If so, spring is the best time to renovate your pastures to make full use of this growing season so that by fall you can have a healthy, nutritious, productive pasture again.
Renovate or Start Over?
A little tender loving care can turn some pathetic pastures into prolific producers with a minimum of effort and expense. But some problems are too difficult to correct, in which case you are required to start over. A worst-case scenario means you'll need herbicides or lots of farm equipment to plow out the existing vegetation, prepare a proper seed bed, and plant new grass. This requires a lot of effort and expense, and you'll need to keep horses off until the new grass is established, which can take up to a year.
Your local extension agent or crop consultant can help you evaluate if your pasture is salvageable. He/she can also provide information on cost, the chance of success for various treatment options for your area, and selection of grasses for your soil types.
Paying for professional advice in the planning stages is cost-effective compared to the expense of tearing up a field and starting over if it's really not necessary, or using products that don't work. If budget is limited, renovating a small area of your pasture every year is a better long-term plan than managing your whole acreage with substandard methods. Proper farming methods are more cost-effective in the long term, and once you see the results on a portion of your pasture, you'll feel far better about doing the rest correctly.
Is there enough desirable grass to fill in with fertilization and rest? This depends on whether it's a grass species that spreads, or a species that might spring up from dormant seeds when conditions allow.
To test this theory put up four panels, or use solar electric tape, in a problem area. Mow weeds as needed and fertilize appropriately, but don't let any animal graze it. If it starts looking like pasture again, you can take the easy route; put in some cross fencing and start a system of rotational grazing and intensive management. Drilling grass seed into existing sod might be enough to increase desirable species if your weed problems can be controlled by herbicides or mowing.
The best defense against weeds is a thick, vigorous stand of grass. Mother Nature doesn't like bare ground. Annual weeds are those that come up from seeds every year. If you cut off the tops with mowing, they cannot produce seed and therefore won't come back next year. Mowing regularly depletes the weed seed bank in the soil over the years. Annual weeds are also easy to kill with herbicides such as 2,4-D or Banvel.
While annual weeds can be controlled by mowing, perennial weeds (those that come back year after year from the same root) are only discouraged for a time and can come back with a vengeance. If a weed has underground runners that branch off the root system, mowing can actually increase the number of new shoots. Tillage only spreads the pieces around and makes it worse. These plants generally require herbicides for control, but herbicides such as Roundup are non-selective, meaning they kill everything you spray them on. Hence this is reserved for spot applications, or where you need to kill off large areas of undesirable species to make a clean start.
Certain perennial weeds can be killed with selective herbicides that will not harm the grass. Examples of these herbicides are Cimmaron/Ally, Redeem, or Grazon.
Your options depend on the weeds, soil type, climate, topography effects of herbicide runoff, depth to water table, and the grazing interval limitations of the herbicide best suited to kill that type of weed. Get qualified help to make these complicated decisions to minimize environmental impacts and use your money wisely.
Fertilizer and Correct pH
The best way to maintain weed-free, vigorous, sustainable pasture is to make sure it has the nutrients it needs to stay healthy and competitive, and a wonderful side effect is that it can then provide better nutrition to your horse. Start with a comprehensive soil test to determine its needs. Fertilizer is expensive, and over-application can impact the surrounding environment. This is not one of those situations where "if a little is good, more is better."
If you live in an area with acidic soils, request a lime requirement recommendation from the soil testing laboratory. Using information from pH (acidity) and soil texture, this will tell you how much lime you need to apply to optimize grass growth and nutrient availability. If your pH is above 8.5 or below 5.5, correction of pH by appropriate amendments is the most important thing you can do for grass production (a pH of 7 is neutral). Spend money here first. Certain weeds only grow in extremes of soil pH, so correction can assist in controlling them.
In high-rainfall areas with very acidic soils (low pH), lime might need to be applied at very heavy rates at first, then kept up every year to stay ahead of problems associated with acid soils.
For alkaline soils (high pH), elemental sulfur can be mixed into the soil, or liquid fertilizers containing sulfur can be applied. The sulfur is eaten by bacteria that will slowly create acid and bring the pH down to a range better suited for growing grass.
Nitrogen is the most commonly deficient nutrient in pastures, and it is the most cost-effective to apply. An investment of $20 per acre for nitrogen fertilizer can triple grass production. Smaller applications through the season are better than one big application to avoid run-off and leaching. Applying nitrogen on top of spring snow is an excellent way to get nitrogen to dissolve and melt in slowly.
Phosphorus helps grass grow a strong, deep root system, and it is vital to development of strong bones in young horses. Topdress applications are better than nothing, but this nutrient is more effective when mixed into the soil. More on this later.
Many soils in the United States have plenty of potassium. As it is recycled in manure and urine, soil that has had manure applied repeatedly can be very high in this nutrient. But if your soil sample says it's deficient, you'll need to add it to help grasses combat drought and cold stress. Potassium fertilizer tends to be salty, so large applications can burn. It's easy to stay caught up with topdress applications.
Magnesium can be supplied by using dolomite limestone. Be very careful with applications of magnesium sulfate, as it can scorch the grass due to its salty nature.
Applications of zinc can improve the trace mineral nutrition to your horses, but it's tricky to get grass to pull copper out of the soil. Talk to local specialists before wasting money on trace mineral fertilizer.
Clover is a sign of nitrogen deficiency and overgrazing. Clover makes its own nitrogen, so when nitrogen is lacking, clover grows well. Close grazing and mowing encourage its growth. To control clover, fertilize with nitrogen early in spring to give grass an advantage. When the grass gets a jump start, it will shade out the clover and keep it under control. Most broadleaf herbicides will also control clover. You can mix liquid fertilizer with some herbicides and rejuvenate your pasture with one pass of equipment.
When to Start Over
When ignored too long, abused and neglected pastures reach the point of no return. If toxic weeds encroach, it might not even be safe for turnout. If all the desirable species are gone, you have large areas of perennial weeds with branching root systems that are difficult to kill, or undesirable grasses such as foxtail barley or endophyte-infected fescue. Killing the undesirable plants with herbicide or repetitive cultivation are the only options.
While some people prefer to avoid use of chemicals, controlling undesirable perennial weeds or grasses might take a whole season of repetitive tillage, and fuel costs alone can be high, not to mention the loss of use of the pasture. One heavy application of Roundup can kill everything, and you can plant grass right away because it has no activity in the soil. Let the Roundup work for two weeks before you start tillage to make sure it kills the weed roots.
If you need to add lime, the best time to get a large amount applied that can be mixed thoroughly with the soil is before you re-sow the grass. Surface applications are best for maintenance after major adjustment of pH is achieved. Mixing lime with the soil throughout the rooting zone will relieve stress from tender roots of baby grass plants, so don't scrimp.
Using recommendations from your soil test, provide enough phosphorus to last for several years. Phosphorus is held by soil particles; it does not leach out like nitrogen. High phosphorus levels are like money in the bank for farmers, and like lime, they do a lot more good when mixed in the topsoil.
You won't need nitrogen the first year when you reseed grass. If you plowed under existing vegetation, you'll get some nitrogen recycling as it decays. Too much nitrogen can burn tender shoots, and the grass needs to grow slowly and develop a strong root system.
Proper seed bed preparation is vital. Soil must be worked to eliminate clods and packed slightly to facilitate good contact between moist soil and developing roots. Grass should be drilled within the top one-half to three-quarters of an inch with a drill designed especially for small seed.
Depending on your climate and weather, you might get a better stand of grass if you plant small enough areas to provide irrigation until the grass is well-rooted. Irrigation is not needed once grass is established. For new pastures in areas with borderline rainfall, plant grass before the rainy season.
Keep horses off until you are unable to pull new grass plants out by the roots. This will probably take a couple of months to a full season depending on conditions and grass vigor. Even when well-rooted, grazing new grass too early or too hard can weaken it so that it might not survive winter.
While it sounds like a lot of work, when your pasture is again producing nutritious grass, with solid, protective sod that crowds out toxic weeds, you and your horses will appreciate the effort.
POLL: University Equine Hospitals