“Having your soil tested is the foundation to knowing what fertilizer amounts your pastures and grazing forages need,” said Leo Espinoza, University of Arkansas extension soil scientist.
Cows need to use nutrients provided from grasses efficiently, testing soil nutrients to ensure this allows producers to have this optimal performance opportunity when managing their cattle. “Any fields that haven’t been tested in the past 10 years should be tested,” Espinoza said.
According to Espinoza, producers should also know that if they have tests conducted after a period of drought (now) or other drastic weather changes, it might be hard to determine any causes of noticeable differences in nutrient levels of the soil. Potassium (K) and phosphorus (pH) levels will be affected by drought. Clay particles will collapse in the soil, changing the K level and balance.
Acidity is a common problem in grazing pastures and grazing fields, producers need to be aware of their pH levels, Espinoza added. Soil pH affects the availability of nutrients to plants and the ability of plants to use fertilizers efficiently.
“All fields, both pastures and hayfields, should be tested every 3 to 4 years, especially if the fertility historically has been marginal on those fields,” said Tim Schnakenberg, regional agronomy specialist for the University of Missouri’s Stone County Extension Center.
Schnakenberg recommends that soil testing can be done any time of the year but it is a good practice to be consistent each time by doing it the same time as the last year of testing.
According to Schnakenberg a soil probe or soil auger should be used to sample soil, these should be available at county extension offices.
“A soil test should be a representative sample from the field, which means it should average what most of the field would be like,” Schnakenberg said. To do this he recommended staying in the open areas of the pasture and focusing mostly on the landscape position that is typical for the area.
According to Espinoza, the samples for grazing land should be taken at four inches, this is shallower than samples for row crops because grazing land isn’t mixed or worked as row crop fields are on a regular or semi-regular basis. When the ground isn’t worked or rotated, stratification of the nutrients occur in the top layers of the soil.
“We recommend 10 to 20 subsamples for each soil test submitted,” Schnakenberg added. “This takes the variability out of the sample. Mix these subsamples together thoroughly and bring about one pint of soil to your local extension office for testing.”
“A standard soil test will show levels, on a per acre basis, of P, K, pH, calcium and magnesium,” Schnakenberg said. It will also provide a reading of the soil pH and organic matter. Based on these numbers, a recommendation will also be provided for what nutrients are needed for the crops specified.
“The value of conducting soil test is not in one single test, it is in a history of tests conducted in the same field or pasture over time,” Espinoza said.
