AgWatch


Test Soil, Control Weeds And Fertilize At The Right Time

HOUSTON, MO.
   Winter is the perfect time to test the soil in a pasture to give forage the proper nutrients when spring arrives according to University of Missouri Extension specialists.
   “Soil samples need to be taken every three to four years and doing that soil test in the winter gives you time to prepare for spring,” said Sarah Kenyon, agronomy specialist, MU Extension.
   COLLECTING SOIL
   Several samples bags need to be collected if the land is uneven. If a field was once two pastures or converted from a crop field, separate samples should be taken on either side of the old fence line. Hillsides and waterways and removed ponds or treelines should be sampled differently.
   “Avoid areas where livestock congregate and edges of pastures near gravel roads,” said Kenyon. “It is best to wait at least three months after application of phosphorus fertilizer, lime or manure before taking a soil sample.”
   Sample cores need to be at six to eight inches deep; too shallow of a sample can cause an overestimate of soil fertility levels.
   “Every core should be the same depth and quantity to provide uniformity. A zigzag pattern of random soil sampling across the field works well in most situations,” said Kenyon.
   If using a shovel instead of a soil probe, dig a hole and slice off one side.
   Collect 10-20 cores in a bucket, crumble and mix them well. Then remove sticks, rocks and grass and place about one pint of soil into a plastic bag or soil sample box. Always label the bag in reference to where the sample was taken to identify it when the results are received.
   ADDING NUTRIENTS
   If pH needs to be raised in the soil, Kenyon says to add lime as soon as possible. Lime takes six months to break down.
   “Correct pH is important to make other fertilizer and nutrients available for plant uptake,” said Kenyon. “If pH is not at the recommended level, nutrients in or applied to the soil will not be completely available for the plant to use.”
   Nitrogen should be applied according to the plant's growing season. For example, fescue is a cool season grass, which means its main growth is in the fall and spring. Since nitrogen is a mobile nutrient, the amount changes from season to season and with weather patterns.
   “The best time to apply nitrogen is right before the main growing season starts, for fescue that is in the spring and fall,” said Kenyon.
   Split the recommended amount of nitrogen on the soil test for an accurate application. Phosphorus and potassium are immobile nutrients, so they can either be applied all at once with the spring application of nitrogen or also split into two applications.
   DON’T FERTILIZE WEEDS
   According to Kenyon, the amount of weeds present on the land should be considered before making a fertilizer application of nitrogen, phosphorus or potassium.
   “If there is a large population of weeds, do not fertilize until control measures for the weeds have been taken. If weeds are not controlled before a fertilizer application, you will be fertilizing the weeds as well as the grass, making them more competitive to the desired forage,” said Kenyon.
   Weed identification is the most important step to making a timely herbicide application or appropriate control.
   “Each weed has a unique growing pattern and life cycle; the timing of control applications are based on these characteristics,” said Kenyon.
   LOWER COST, FASTER RESULTS
   Getting a soil test done at an extension office during the winter gets the producer results faster.
   “February to April are peak months for soil test results and, at least in Greene County, getting your results can take ten days or more that time of year,” said David Burton, county program director in Greene County. “Results in the winter get turned around much quicker.”
   In Greene County, the local office provides a discount coupon of $3 for soil tests during November and December. (See http://extension.missouri.edu/greene for more information). ∆
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