Time to Gather Soil Tests – Del Voight Penn State Extension

With the early harvest this year we have an ideal time to gather soil test information. I had a grower in the other day and he had not sampled his soil for over 13 years and was running into yield issues.  Wow! I have growers sampling every year now and some even in season and then some that dont at all.   Yields are variable in the Region from  less than 150 bu/acre to more than 330 bu/acre corn yield reports.  With high yields the plant food contained in the soil is depleted (200 bu corn crop pulls (80lbs of P and 60lbs of K)and it is important to get a bench mark as to what is left.  Soil test kits available at the local Extension Office for 9 dollars are the best way to indicate the relative amounts of food available for the plants.   A kit is nothing more than a bag and paper its the results that are important.  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.  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! Don’t forget those no till fields need a surface pH as well to get a handle on any acid roof that might form over repeated N applications in this reduced tillage system.

1. Getting the sample now.
   1. You need to ensure that the 10-15 acres that one bag is designed to represent does just that represent the soil profile in that field. 
   2. Get the correct DEPTH 6 and 2/3 rd is ideal. I had a grower that each year his testing swayed wildly turns out he was sampling 12 inches deep! Only 6 inch which is what all the recommendations are based upon. 
   3. By and large the plant food (fertilizer) industry has offered the service of pulling the soil test but it is still up to you to ensure that the sample comes from the correct field. It must represent the soil type and the field may need to be split into small parcels correctly.  A typical 200 acre farm would cost about 180 bucks in testing fees and take about a half a day to gather samples. If that is too much then do part of the farm each year.
   4. Take samples yourself or be sure a consultant with proper training is collecting them.  Order enough kits to cover the fields that are due for testing.

• 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 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!
• Overall planning
  1. Have a plan!  Determine a method for your farm that allows for timely three year testing or shorter.  See if grid sampling applies (this could mean testing on a five year plan).  Avoid “rented ground syndrome” where some farmers (turned miners) forget the building blocks for maintaining yields.  Soil test, work with landowners, find solutions to providing the needs and not mining the soil. By the way, research indicates that depleted soils may take much more money to bring back fertility than adequately maintained soils.
  2. Plan to sample by rotations.  Many growers I work with will soil sample soybeans then fertilize (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.
• pH issues
  1. Lime ¼ to 1/3 of your farm each year.  This eliminates the tremendous bill and ensures that pH is maintained for the whole farm.
  2. On no till ground, turf areas, pastures, and alfalfa gain 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.

It’s that time of year to gather the tests.  Get a plan, get the kits and get it done.  I will write my cheat sheet in a future article detailing the benchmarks you need to know in order to read your soil test results.