High oil prices don't just impact your bank account at the fuel pump. Commercial nitrogen fertilizer production is heavily dependent upon fossil fuels. In the four years I have worked as a forage specialist, nitrogen fertilizer have more than doubled from $0.24 per unit to well over $0.50 per unit. Even with high cattle markets, it is imperative to control fertilizer input costs. Included in this article are several tips to decrease your farm's dependence on external nitrogen sources.
1. Select species tolerant of low fertility
Some forage species may not produce high yields like hybrid bermudagrass, but are more tolerant of low fertility situations. Bahiagrass is a warm season perennial forage available to South Carolina producers in the Low Country. Bahiagrass is tolerant of poor drainage, droughty soils, heavy grazing and low N, P and K inputs. It is also capable of fixing small amounts of nitrogen (only 15 or 20 lbs per acre) which helps maintain stands.
Please note that unfertilized bahiagrass is not extremely productive, but will normally survive well in low input situations.
Bahiagrass is responsive to nitrogen applications and will produce good yields when managed and fertilized properly. In the upstate, tall fescue, annual lespedeza and sericia lespedeza are also tolerant of low fertility.
2. Incorporate annual or perennial legumes
Legumes can capture atmospheric nitrogen and "fix" it into a form that companion grasses can utilize. Annual clovers like crimson and arrowleaf can be overseeded into bermudagrass or bahiagrass in the fall and are capable of fixing about 100 units of N per acre. This nitrogen is normally released in spring and early summer and typically benefits bermudagrass during greenup early season growth.
Perennial legumes like red and white clover can fix over 150 units of N each season and are well suited to tall fescue pastures.
While it is too late to overseed cool season legumes into tall fescue or bermudagrass pastures this year, consider planting them this fall into pastures. The fixed nitrogen from legumes will more than cover clover seed costs and the increased grazing days and forage quality will be a nice bonus for your cattle. Most annual clovers (except for arrowleaf and ball) must be replanted every year due to undependable reseeding, and perennial clovers normally last only one or two years when overseeded in bermudagrass.
Legumes often cannot be immediately incorporated in pastures. Soil must have a favorable pH and contain adequate levels of potassium and phosphorus for successful establishment and persistence.
Sample soils now and apply recommended lime so that fields will be ready for planting this fall. Recommended phosphorus and potash can be applied now or later in the summer depending upon the immediate needs of the tall fescue or bermudagrass stand.
Broadleaf weeds must also be controlled before seeding clover in pastures. Once clovers are seeded in pastures, control of broadleaf weeds is difficult or impossible.
Before planting clover, time herbicide applications to achieve good weed control while still allowing an adequate period for residual activity to disappear. Length of residual activity depends upon the herbicide used, the rate applied, and weather conditions following applications. Check the herbicide label to determine appropriate application rates and timing for various weeds.
Consider the soil and management requirements of clover species. All clovers are not created equal.
For example, white clover will tolerate poorly drained soils while red, arrowleaf and crimson clover will not.
Some legumes tolerate low soil pH and others require soils with a pH of 6.5 or higher. Visit with your local county extension agent to determine which clover is right for selected pastures and management styles.
3. Utilize chicken litter
Why spend hard earned money on commercial fertilizer when poultry litter can often be purchased for less money? Actively search for litter sources in your area. With ammonium nitrate costs steadily rising, it may also pay to ship litter greater distances this year. A "typical" ton of poultry litter contains 60 lbs of N, 60 lbs of P205, and 40 lbs of K2O. If only the nitrogen is credited at 50.55 per unit and this nitrogen is 60 percent available, a ton of litter is worth approximately 519.80 applied.
Of course, additional value can be credited for the potash and phosphate present in the litter. Be sure to test poultry litter for nutrient composition as nitrogen content can vary widely. Some litter may only contain 20 pounds of nitrogen per ton, which would only be worth $6.60 per ton using the above assumptions.
4. Practice rotational grazing
Nitrogen and other nutrients "cycle" through pasture systems. For example, the ammonium nitrate applied on pastures this spring will be taken into plants, consumed by animals, then excreted in dung and urine.
During this process, some of the nitrogen will be lost to the atmosphere, some will be deposited in the animal and some will be reabsorbed by plants from urine and dung.
How does rotational grazing help this process? First rotational grazing allows urine and dung to be spread more uniformly across pastures which decreases needs for imported nutrients. Second, rotational grazing helps keep plants in a more vegetative and active growth phase which should increase the efficiency of nitrogen use. Judicious use of rotational grazing can also improve forage budgeting and decrease hay requirements which also require expensive nitrogen inputs.
While it is difficult to totally eliminate N applications on grass pastures, hopefully these tips can decrease dependence on costly inorganic fertilizer sources. Closely examine purchase prices of locally produced hay. It may be more economical to buy rather than produce bermudagrass hay this year. Also closely examine low input forages that, although less productive, can fit well into cow calf grazing systems. Legumes and poultry litter are excellent sources of nitrogen which can benefit pastures and hayfields.
Rotational grazing helps to recycle and distribute nitrogen more uniformly across pastures thereby decreasing fertilizer needs.
[John Andrae is an extension forage specialist at Clemson University.]