Some Soil Testing Ideas

Posted: September 30, 2014

Develop a plan, get the kits and get it done

Recent surveys indicate that 20% of the fields in PA 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 lbs. of P and 60 lbs. of K. It is important to get a bench mark as to what is left. I have seen yellow corn, beans, stalk rot and mycotoxins from low K, purple corn from low pH and low P 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 three year testing or shorter. Many growers I work with will soil sample soybeans then fertilize with P and K, either from manure or commercial source, in the fall for both a corn and soybean crop. Thus, in the crop season only N requirements are needed and it eliminates the following year application. Remember P and K do not move in the soil and thus this can be a management suggestion.
  • Take samples yourself or be sure a consultant with proper training is collecting them.
  • You need to ensure that the 10-15 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. When I was working in this area I could get 400 acres sampled by noon. Frozen soil slows the process down. With ATV’s and other devices it should be a fairly speedy process. Label the bags first get them in a box in order and 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 N 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. I 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.

Contact Information

Del G. Voight, M.S
  • Senior Extension Educator - Agronomy
Phone: 717-270-4391