Fertilizing Bermudagrass for Hay and Pasture
|Soil pH and Lime Needs||Potassium Recommendations|
|Nitrogen||Secondary Elements and Micronutrients|
|Phosphorus and Potassium||Manures and Other Organic Fertilizers|
J. Sandage, Extension Forage Specialist
Stanley L. Chapman, Extension Soils Specialist
Yields of bermudagrass are usually controlled by temperature, moisture and fertility level, especially nitrogen. Bermudagrass persists with little or no fertilization, but balanced fertility is necessary to produce high yields and maintain adequate stands.
Most bermudagrass varieties and hybrids developed in the southeastern United States are quite tolerant of acid soils. Coastal and Tifton 44 are good examples. Those developed west of Arkansas (such as Hardie, Guymon, Brazos and Greenfield) are not as tolerant. Apply lime only on the basis of a representative soil test. Lime is recommended for bermudagrass establishment when the pH is below 5.8 for soils in the southern half and eastern third of the state. For the northern half of the state, lime is recommended for soils with pH values below 6.
Lime costs increase, generally, from northern to southeastern Arkansas. This is why lime is not recommended until the soil pH drops below 5.8, instead of 6.0, for soils in the southern and eastern areas of the state. Also, bermudagrass may suffer less cold weather damage when acid soils are limed. This is especially important in the northern counties.
Recommended lime rates range from 1 to 3 tons per acre depending on soil pH and texture. The lower rates are for sandy soils; the higher rates are for clay soils.
Bermudagrass requires about 50 pounds of N for each ton of hay-equivalent forage produced. The actual amount of N varies from as little as 25 pounds for a ton of poor-quality grass to as much as 100 pounds for a ton of high-quality forage containing as much as 25 percent crude protein.
Most Arkansas soils supply very little nitrogen during a single growing season. About 40 pounds of N per acre is considered a normal release rate. This is enough to produce about one ton of dry forage. Fertilizer N is generally needed for additional production.
Hay-equivalent production levels and recommended N rates have been established for bermudagrass in Arkansas as follows:
Levels of Production (Tons/Acre)
Total Fertilizer N Needed (Pounds N/Acre)
|Low (below 2)||
|Very high (above 8)||
Fertilizer N is normally applied as follows:
(1) 40-50 pounds of N/A is applied with any required P and K about the first of April. This application may be made a week or so earlier in extreme south Arkansas and a week or so later in extreme north Arkansas.
(2) 60-70 pounds of N/A should be applied after each hay cutting or every 4-6 weeks of grazing for medium to high production.
(3) 80-100 pounds of N/A should be applied after each hay cutting or every 4-6 weeks of grazing for very high production.
Phosphorus and potassium fertilizer needs by bermudagrass vary according to soil test levels. Apply all of the P and all or part of the needed K with some N about April 1 or first green-up. You may apply phosphorus and potassium without N in February or March. Then apply the N separately after growth starts in April. Additional K is recommended with N after every other hay cutting or grazing period if high or very high yield levels are desired.
The University of Arkansas Cooperative Extension Service recommends a spring application for fields with soil test P levels of medium or below (less than 100 pounds by Mehlich III extraction procedures). Recommended rates range from 40 to 90 pounds of P2O5 per acre depending on soil test P and desired production level. Phosphorus and potassium are normally applied together if both are needed.
A spring application of K is recommended for fields with soil test K levels of medium or below (less than 300 pounds by Mehlich III extraction procedures). Recommended rates range from 40 to 120 pounds of K2O per acre depending on soil test K and desired production level. Additional applications of 80-100 pounds of K2O per acre are recommended after every other hay cutting or grazing period if high and very high levels of production are desired.
If stands become weak, consider applying K just ahead of the last hay cutting or grazing period in the fall. This ensures that plants are healthy as they go into the winter. Fall-applied K serves as an "anti-freeze" for the bermudagrass. There is little chance of losing fall-applied K, in contrast to fall-applied N for bermudagrass.
Calcium levels are normally adequate as long as liming needs are met.
Magnesium levels are low (below 75 pounds by Mehlich III extraction) in many acid soils with low cation exchange capacities. These include the sandy to silt loam soils of the upland parts of the state as well as the Coastal plain and other specific areas of local importance (Figure 1). Dolomitic limestone is recommended as an alternate liming source since it supplies magnesium. Pure dolomitic lime contains about 12 percent magnesium, but any liming material with more than 6 percent magnesium has been defined as "dolomitic" for our purposes in Arkansas. Dolomitic lime is available from near Black Rock, Salem and other quarries in northern Arkansas and from the state of Missouri.
Very little research data is available to show that increased bermudagrass yields result from correcting low levels of magnesium in soils. Improving forage quality and preventing animal health problems may be the major benefits from the addition of magnesium.
Potassium magnesium sulfate is a commercially available fertilizer that contains magnesium in addition to potassium and sulfur. Common brand names are Sul-Po-Mag and K-Mag.
Sulfur deficiency in bermudagrass has not been considered a major problem in the past. Low analysis fertilizers such as manufactured 8-8-8, 13-13-13, or 20 percent superphosphate have generally supplied adequate S to meet crop needs. In addition, atmospheric sources have generally supplied 5 to 20 pounds of S/A per year. However, sulfur deficiencies may occur on high-yielding hay meadows where high analysis fertilizers (low in S) are used.
Symptoms of S deficiency are slow growth, thinning stands and a pale green color even after N has been applied. Use plant analysis to confirm sulfur or other elemental deficiencies.
Possible S fertilizer sources include ammonium sulfate, potassium magnesium sulfate, gypsum and elemental sulfur. The most economical choice depends on local availability and the need for the other elements in the fertilizer.
None of the micronutrients (iron, manganese, zinc, copper, boron, molybdenum or chlorine) have been shown to be deficient for bermudagrass production in Arkansas. The availability of these elements is generally controlled by soil pH, organic matter, soil moisture and clay content. Apparent low levels of some of these micronutrients have been detected in plant samples from bermudagrass hay meadows. However, conditions for yield response from
the addition of the micronutrients have not been clearly defined. Soil testing on a regular basis and following routine recommendations are probably the best ways of ensuring an adequate level of micronutrients for bermudagrass production.
Animal manures, poultry litter and other organic by-products may be used to fertilizer bermudagrass. Rates should not exceed more than about 3 tons of dry materials/acre/year for maximum efficiency. A ton of such material usually supplies from about 20 to 50 pounds of nitrogen. This is equivalent to about 60 to 150 pounds of ammonium nitrate. Phosphorus and potassium tend to build up in soils where high rates of poultry litter are used.
Manure is best applied to bermudagrass fields immediately after hay removal or before spring green-up.
Our thanks to DR. CLIFFORD S. SNYDER, former Extension soils specialist, and DR. B. J. HANKINS, retired Extension agronomist- forages, Cooperative Extension Service, University of Arkansas, Little Rock, for their help with the original manuscript of this publication.
University of Arkansas, United States Department of Agriculture, and County Governments Cooperating
|LARRY J. SANDAGE
is Extension forage specialist with the Cooperative
Extension Service, University of Arkansas. He is located
at the Livestock and Forestry Branch Station in
DR. STANLEY L. CHAPMAN is Extension soils specialist with the Cooperative Extension Service, University of Arkansas, and is located in Little Rock.
Issued in furtherance of Cooperative Extension work, Acts of May 8 and June 30, 1914, in cooperation with the U.S. Department of Agriculture, Director, Cooperative Extension Service, University of Arkansas. The Arkansas Cooperative Extension Service offers its programs to all eligible persons regardless of race, color, national origin, sex, age, or disability, and is an Equal Opportunity Employer.