A good fertilization program is necessary to produce high yields of quality forage and to maintain healthy stands of grasses and legumes. Coming out of winter, many producers want to give their pastures a boost, but what is the optimal time or most economical way to do that?
“With the cost of fertilizers increasing, the best dollars spent is on a soil test,” said Paul Beck, Ph.D., professor, University of Arkansas Southwest Research & Extension Center. January and February are peak months for soil testing prior to spring fertilization. “Soils should be tested once every two years, at a minimum,” Beck said.
“Without the information a soil test provides all you can do is guess, which will normally result in crop loss or poor blooming,” said Tim Schnakenberg, agronomy specialist, University of Missouri Extension. “To make it easy to interpret the soil test results, your report form will indicate which fertilizers and how much you should apply.”
According to Beck, once the soil is tested, producers should make sure the pH is optimal for absorption of the applied nutrients. Beck explained that liming helps micronutrients bound up in acidic soil to be released in a form that plants can utilize.
One way to stretch fertilization dollars is to manage pastures so the grass gets eaten instead of wasted. “Research has shown increased pasture utilization with rotational grazing,” said Brie Menjoulet, agronomy specialist, University of Missouri. “Dividing pastures gives more control to the producer by controlling grazing heights and controlling where cattle redeposit nutrients. Reduced paddock size and more paddocks increase utilization and nutrient distribution,” Menjoulet said.
“Typically, nitrogen is the limiting factor, particularly in fields without legumes. Cattle excrete most of the phosphorus (P) and potassium (K) taken in from forages. Building up low-nutrient soils can help improve forage yields, and after the build-up, maintenance applications of P and K are minimal,” Menjoulet said.
Application timing is important, according to Schnakenberg. “Applying nitrogen too early can potentially lead to losses due to rain and snow events that may occur later in the winter. Applying nitrogen too late could result in missing the window for maximum uptake and yield,” he said.
Menjoulet advised against applying nitrogen if seeding a legume, since it would stimulate grasses to grow and increase competition. “If pastures are thin after last year’s drought, it (seeding legumes) might be a good option. But if soil is nutrient deficient, seeds may have trouble germinating, which would be a waste of time and money,” she said.
“Because nutrients are surface applied on pastures, it takes more time for the P and K to move into the root zone. Soils with low P and K may not respond to an application until later on in the growing season,” Menjoulet said. “Fescue typically yields more in spring, so spring fertilizer applications make sense. Split applications of nitrogen are best if the pasture is being used year round.”
For a Fescue pasture without clover, Menjoulet suggested applying 40 to 60 pounds of nitrogen per acre in the spring, and then 30 to 50 pounds per acre in the fall.
If fertilizer prices dictate that you simply can’t fertilize all the hay and pastureland that a soil test indicates is needed, Menjoulet advised feeding hay on the same field the hay was harvested from, so nutrients are recycled, instead of being moved from the hayfield to the pasture. “Fertilize fields that will provide you the most yield for dollars spent,” she said.
“Lime and clover are the best approaches for economically enhancing the fertility base of a pasture or hayfield. Clover and lime provide a greater amount of nutrients for the money than what most fertilizers provide,” Schnakenberg said.
