When it comes to Missouri soils, Dr. Will McClain said, “We’re stuck with the soil texture we’ve been given.” The texture of a soil is determined by its mineral matter. Texture is based on the amounts of sand, silt and clay in the soil. An Agronomy Specialist with the University of Missouri Extension, he believes Missouri has some of the most variable soils around.
McClain told Spring Forage Conference attendees at the Feb. 23 conference in Springfield, Mo., it is important to know your soil, because plant species differ in their nutrient requirements. Learning what mineral nutrient you need the most and where it is needed is the best way to save money on fertilizer.
Different areas of a farm, or field, may have differing nutrient needs. Adding too much of a nutrient to the soil can be detrimental. It is easier to deal with a nutrient deficiency than with trying to deal with toxic levels.
Soil testing is the best way to determine what nutrients are in the soil. While it sounds simple, there are proper ways to test to ensure accurate results.
If you are testing a field with one soil type, you might be able to get accuracy with only one sample. But if the field has a lot of variability, more samples may be needed. The University of Missouri recommends taking 15 to 20 cores per sample. The right depth is important. The recommended depth is four to six inches because that is where the majority of plant roots are.
Something as simple as using a clean bucket can make a big difference in testing results. Some substances, or fertilizer residue, in the bucket will show up in the soil test as very high values.
Avoid testing in areas where the animals hang out. Also avoid sampling near a limestone road. The closer you get to a chat road, the higher the pH. The measure of soil acidity is called pH. Most plants grow best in the 5.5 to 6.5 pH range.
Test results may have a number under the EMG (effective magnesium). That means dolomitic limestone is needed. A number in the ENM (effective neutralizing material) means calcitic lime should be used.
Soil is composed of many factors. The most limiting nutrient determines the overall yield potential. A large portion of Missouri soils are low in phosphorus. When phosphorus was added, an increase was seen in yield and root mass.
The University of Missouri recommends one pound per acre, per year of Boron for alfalfa. Boron is needed by legumes.
Dr. McClain said there are benefits to unrolling hay in the field. Some contend this method wastes hay, but, he declared, it saves on fertilizer. Unrolling the hay causes the manure to be distributed around the field. Over a period of time it will cut down on the fertilizer needed. One cow on hay for 100 days (assuming 30 lbs/day) produces 25 pounds of available nitrogen, 21 pounds of phosphate and 73 pounds of potash.
A great online tool is the website for the Center for Applied Research and Environmental Systems, and you can access that page at www.ozarksfn.com.
