Pasture Reminders for March 2006
Jim Green
Crop Science Department
North Carolina State University
For the most part winter has been rather mild, which could mean early green up of some of the gasses like fescue, orchardgrass, bluegrass, prairiegrass (Matua), smallgrains and ryegrasses. If these grasses green up and put out some leaves they may be grazed, but do not graze them below about 3 inches the first time. The plants have been dormant or semi-dormant and the new leaf growth will mean that the reserve energy stored in the stem bases or rhizomes of the plants has been used to produce some of this early leaf development. After the plants have had 5-8 inches of growth much of the energy will be replenished and the plants may be grazed back to 2-3 inch stubble in subsequent grazings.
Fertilization plans should be put into place early this month. It is relatively easy to grow grass in April and May, but the amount will hinge on how much N is available to the plants or what percent of the stand is clover. As a general rule, one lb of N results in 15-25 lbs of dry yield matter yield response up to about 100 to 150 lbs N/acre/year. The response per lb of N is less at the high end of the application rate than it is at the low level. If N is costing $.50 this spring and the average response is 20 lbs/ lb of N, then the cost of the additional dry matter is $.025/lb. Of course N is not the only cost of producing forage. It is estimated that it costs about $130 to $140/ acre to grow a crop of cool season grass (yielding about 3 tons/acre); this assumes purchased fertilizer, depreciation, interest and labor. Under ideal grazing management 60 to 75% of what is grown will be consumed by the animals. With all of these assumptions it means the cost of each pound of dry matter down the throat is about $0.03. If the pasture growth is harvested as large round bales there is another cost of $45 and $65 per ton, which amounts an additional $.02 to $.03 per lb of dry matter, excluding the waste that may occur in storage and feeding.
Determining when to apply N to cool season grasses hinges somewhat on when one wants the growth response. The most dry matter per lb of N will come when the N is applied just prior to the favorable growing conditions; this is usually during the spring months. To get the most uniform distribution of growth through-out the year and the best efficiency of use, it is best to split N into 2 or 3 application times. For example, cool season grasses generally respond to about 150 lbs N/acre/year and applying 50 lbs/acre in early March, 50 lbs in early May and 50 lbs in late August or early Sept will provide relatively uniform growth and efficient use of the N. However, when applying 100 lbs N/acre/year or less it is probably most efficient to apply half in March and half in August-September. The autumn application is really critical for providing additional grazing in the fall-winter period. Autumn accumulation of grass that can be grazed in November through February is one of the best ways to reduce winter feed costs.
Limestone, phosphate (P2O5) and potash (K2O) may be applied on most soils in any time during the year, however, on sandy textured soils potash is often split with some applied in spring and some in mid summer. Potassium (K) is subject to leaching much like N and S on such soils.
If you have already planted clover into fescue or orchardgrass pastures you should walk the fields to see how the developing seedlings are doing. Seedling survival is very highly related to the amount of sunlight they receive during the early stages of growth. Shading by the associated grass is most often more damaging than the grazing animal. Keep the grass grazed below 4-6 inches during the first month following overseeding, and do not let it reach more than 6-8 inches during the April-May period; this means you have to have the pastures fenced so that animals can be grazed for a few days and then moved off the area for a few weeks before returning.
If you have all cool season grass on the farm you should strongly consider planting some portion of the acreage to a warm season grass like bermudagrass. Other warm season grasses that would help the forage supply on the farm include crabgrass, dallisgrass, switchgrass, and bahiagrass.
The odds of successfully establishing hybrid bermudagrass are improved when the dormant sprigs are planted rather than the non-dormant. Some hybrids may be planted from clippings of mature above ground stems (Tifton 85), but success is very strongly related to soil moisture levels the first 3-5 days following planting. Tifton 44 or Midland 99 are the most winter hardy hybrids and could easily be grown in the whole piedmont region. Tifton 44 was grown at the Waynesville research station for 5 years with no significant winter damage. Local ecotypes of bermuda may be found growing in pastures and along roadsides in Buncombe, McDowell and other mountain counties.
Harvest or graze winter crops (cereals, ryegrass, and prairiegrass) which were overseeded onto bermuda last fall. Late harvesting of the winter crop is the number one reason why many swine effluent application sites do not have good stands of bermudagrass after a couple of seasons. Allowing the winter crop to continue to grow un-harvested or un-grazed in the March-April period results in severe shading of the emerging bermuda plants. Actually, one of the best bermudagrass control techniques is to grow “shade” crops on bermuda for a season or two.
Many winter “weedy” plants will be showing up in March. If you cannot manage to force the animals to graze them, then consider whether or not they are thick enough to mow or spray with an appropriate herbicide. It is usually best to let the animals eat weeds if possible, but sometimes certain weeds are not readily eaten. Restricting the area animals have to graze can alter their willingness to eat all plants. Animals are selective much the same as people; when we have a wide choice and plenty of freedom, we may eat only a select few things, but when the selection on the table is narrow we usually eat what is there. Remember, when you see the beautiful yellow flowers in the pasture, it is too late to do much about them; just marvel at them and plan to do better next year.
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