Recent surveys indicate that 20% of the fields in Pennsylvania do not have a current soil test. With high yields, the plant food contained in the soil is depleted more rapidly. A 200-bushel corn crop pulls out 80 pounds of phosphorus and 60 pounds of potassium. It is important to get a benchmark as to what is left.
We have seen yellow corn, beans, stalk rot and mycotoxins from low potassium, purple corn from low pH and low phosphorus, and numerous ear malformations from lack of fertility that could have been avoided with a simple test. Soil test kits available for $9.00 at the local Extension Office are the best way to indicate the relative amounts of food available for the plants.
• Have a plan. Determine a method for your farm that allows for timely 3-year testing or shorter. Many growers will soil sample soybeans then fertilize with phosphorus and potassium, either from manure or commercial source, in the fall for both a corn and soybean crop. Thus, in the crop season only nitrogen requirements are needed and it eliminates the following year application. Remember, phosphorus and potassium do not move in the soil, and thus this can be a management suggestion.
• Take samples yourself or be sure a crop consultant with proper training is collecting them.
• You need to ensure that the 10 to 15 acres that one bag is designed to represent does just that. Errors occur when the sample is taken without regard to ensuring it represents the area to be tested. Some growers try to stretch a bag to more than 10 acres and that reduces the confidence that the test is accurate.
• Plan a day to gather the samples. Frozen soil slows the process down. With ATVs and other devices it should be a fairly speedy process. Label the bags first get them in a box in order, then go get them.
• Don’t forget those no-till fields need a surface pH test as well to get a handle on any acid roof that might form over repeated nitrogen applications. On no-till ground, pastures and alfalfa, take a 2-inch soil sample and test for pH. This can be done with at-home testing kits. We recommend the Cornell PH test kit. This might be the most important aspect of your fertility plan.
• Lime 1/4 to 1/3 of your farm each year. This eliminates the tremendous bill and ensures that pH is maintained for the whole farm.
Fall is an ideal time to gather soil test information. Get a plan, get the kits and get it done.