By Staff
Justin Rodgers / 4-H youth agent
April 21, 2002
The quality of the forages your land will produce is dependent upon the amount of soil fertility. Almost all Mississippi pastures require fertilizer to provide nutrients for forage growth and survival. To be able to grow quality forages, we must understand nutrient management practices. The most common fertilizers applied to pastures are nitrogen, phosphorus, and potassium.
Nitrogen is the most often used of these three elements. Nitrogen is the growth element that will help grasses produce rapid, vegetative growth with favorable growing conditions. Grasses take up most of their nitrogen in the nitrate form, which is quickly converted in the plant tissue to protein. When poor growing conditions occur such as cool, cloudy weather or droughts, the growth is slowed reducing the protein uptake, but not nitrate production if the soil supply is high.
When these conditions are present, the risk for toxic levels to livestock can occur. The amount of nitrogen applied will depend on the target yield, not on a soil test, as this is not commonly a part of soil test recommendations. Usually warm season grasses will produce more forage than cool season grasses when nitrogen is applied.
Phosphorus is generally low in Mississippi soils unless it has been applied as fertilizer previously. It will not readily leach from the soil profile, so in grazing situations it can be easily maintained or even accumulate. Phosphorus could be more of a problem with soil erosion going into water creating surface water quality problems. Much of the phosphorus that is used by cattle is recycled back into the soil in the manure.
Potassium is needed in much larger amounts by forages, in fact nearly equal to nitrogen.
Adequate potassium is needed by forage plants to maintain strength through the winter. It can also be quite mobile in the soil profile, so it is not generally built up over time. Potassium should be replaced at a rate of 30 to 40 pounds per acre.
Other elements such as calcium, magnesium and sulfur also are needed to maintain pasture growth. These elements are usually applied to the soil in lesser amounts in specially blended fertilizer mixtures. If your soil acidity, or pH, was less than 5.5, which is common with Mississippi soils, your pastures would benefit from an application of lime. One usually applies lime at the rate of 1 ton to the acre, which should increase your pH by 1 number.
Be sure to have your soil tested each year before deciding on a type of fertilizer. This will save you time and money in the long run and help you to gain the maximum amount of forage from your property.
For assistance with your pasture fertility program contact your local County Extension Service at 482-9764.