The high cost of fertilizers has led some graziers to conclude that they can no longer afford to fertilize their pastures.
Forage has now become an expensive feed. With hay prices expected to remain high in the foreseeable future, forage produced in a pasture situation becomes more valuable, as well.
The question might well be: Can we afford to let pasture land be any less productive than hay or even row cropland?
Productivity is strongly associated with soil fertility. Are there options for graziers to increase soil fertility and increase pasture production without spending huge sums of money for synthetic fertilizers?
Tools
I would like to suggest that graziers do have some tools at their disposal to do this, with grazing management being a primary tool. Pastures have an advantage over hay and most row crop production systems because fewer nutrients are removed and more nutrient recycling occurs.
In contrast to hay production where each ton of hay removes in the neighborhood of 40 pounds of nitrogen, 14 pounds of P2O5 and 50 pounds of K2O, a grazing animal will return between 75-85 percent of the nutrients consumed back to the pasture in the form of urine and feces.
In addition, there are often nutrients added to the system in the form of hay, grains and minerals.
Theoretically, once a pasture has a good soil fertility base, nutrient recycling by grazing livestock should allow that fertility to be maintained. (Good news.)
Unfortunately, the reality is that grazing animals move nutrients. (Bad news.)
Concentrated nutrients
In most grazing situations, livestock remove nutrients from some areas of the pastures and concentrate them in other areas. The result is areas of low soil fertility and areas of high soil fertility within the same pasture.
Those areas of nutrient concentration tend to be near water, shade and mineral feeders. It is not uncommon to see phosphorus and potassium levels in these areas four- to 10-fold higher compared to the rest of the pasture.
To make matters worse, even though nutrients are concentrated in these areas, pasture production is still poor because plants have been overgrazed and trampled.
The problem is manure distribution.
I have yet to hear a grazier say that they have too many pasture paddocks.
By applying pasture management to grazing livestock the grazier can improve distribution, take advantage of the nutrient recycling that occurs in a pasture system and reduce purchased fertilizer expense. This can be achieved by increasing the number of paddocks in the grazing system.
A study done by Jim Gerrish when he was with the University of Missouri Forage Systems Research Center demonstrated this concept.
Paddock numbers
Manure piles from cattle were counted in random areas throughout a pasture system with three paddocks, 12 paddocks and 24 paddocks.
The overall acreage remained the same, only paddock number increased.
Nutrients, as represented by the number of “cow pies” were very unevenly distributed in the three-paddock system, with areas of high concentration around water tanks and shade trees.
As the number of paddocks increased, along with water tanks in each paddock, nutrients became more evenly distributed.
At the 24-paddock level, there were only a few areas of nutrient concentration; most of the pasture area had similar manure distribution.
While it may not be practical for every grazier to have 24 paddocks, it is my observation that as graziers learn more about pasture management, paddock numbers increase. I have yet to hear a grazier say that they have too many pasture paddocks.
More paddocks on a given pasture acreage means smaller paddock sizes. Putting the same number of grazing animals into a smaller space for shorter grazing periods will result in more uniform grazing, better forage use and more uniform manure distribution.
Benefits
The net effect is that soil fertility levels and the corresponding forage production can be maintained for longer periods of time without purchase fertilizer inputs.
One additional benefit that graziers may see in their pastures as they apply more management and increase paddock number is increased soil organic matter levels.
The more uniform grazing and better manure distribution, when combined with providing the proper plant rest periods, results in healthier more voluminous root systems.
As roots grow and die, organic matter is increased. This can have a significant impact on soil fertility and pasture production. Organic matter provides sites to bind and hold nutrients, improves soil structure and increases water infiltration.
While organic matter levels are not present at high percentages in the soil, every 1 percent of organic matter on a per-acre basis contributes 20 pounds to 30 pounds of nitrogen, 4.5 pounds to 6.6 pounds of P2O5 and 2 pounds to 3 pounds of sulfur per year. Other micronutrients are also contributed.
Because soil organic matter can hold up to 90 percent of its weight in water, a 1 percent increase in soil organic matter can result in an additional 2,000-plus gallons of water per acre being available for plant growth.
Other tools
I need to mention a couple of other “tools” available to graziers to help them reduce purchased fertilizer expenses. They include adding legumes to the pasture mix and soil sampling.
A paddock containing 25-30 percent evenly distributed legumes, such as red or white clover, will provide the nitrogen needs for the grass and eliminate the need for purchased nitrogen fertilizer.
Use soil sampling to make more effective and efficient use of purchased fertilizer.
Even if pastures are not divided into smaller paddock subdivisions, divide the pasture into smaller soil sampling units. The idea is to do some type of grid sampling that will permit variable rates of fertilizer to be spread across a pasture according to need.
Soil sampling is cheaper than either over- or under-applying fertilizer over a large area.
(Rory Lewandowski is an OSU Extension educator in Athens and Hocking counties.)
