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Fertilizer and Ag Lime Grants

Title: Refining Soil Test Recommendations for Wheat

Principal Investigators: Peter Scharf, John Lory, Manjula Nathan, and Anne McKendry Agronomy Department, University of Missouri

Objectives:

  1. Test the performance of current University of Missouri soil test recommendations for predicting wheat yield response to P, K, and S in a statewide network of experiments.
  2. Explore the possibility that subsoil test values, soil type, or soil region could be used to improve our fertilizer recommendations and make them more site-specific.

Methods:

  • Experiments will be added to an existing statewide network of 7 wheat variety trials conducted by the University of Missouri. Experiments will be adjacent to but separate from variety trials. A research specialist will arrange with cooperating producers to conspicuously mark the experimental area where P and K fertilizers will not be applied. Variety testing personnel will plant, fertilize, and harvest the experiments.
  • Two experiments will be located in northern Missouri, 1 in central Missouri, 2 in southwest Missouri, and 2 in southeast Missouri.
  • P, K, and S fertilizers will be hand-applied to separate plots at rates of 80 lb P2O5, 80 lb K2O, and 20 lb S/acre. These rates should be high enough to produce full yield response. Yields of fertilized plots will be compared to yields of unfertilized check plots.
  • Six replications will be used.
  • Soil samples will be taken at depths of 0 to 6, 6 to 12, 12 to 24, and 24 to 36 inches in each experiment and analyzed for pH, P, K, and S.
  • One well-adapted variety will be used at each location.
  • Yield response data will be analyzed to assess the performance of current University of Missouri soil test recommendations and to look for ways to improve our recommendations, possibly including subsoil test values, soil type, or soil region.
  • All experiments will be in rotation.

2000-2001 EXPERIMENTAL SITES
LOCATIONCOUNTYSOIL SERIES
PortagevillePemiscotTiptonville Silt Loam
TrentonGrundyGrundy Silt Loam
NoveltyKnoxKilwinning Silt Loam
ColumbiaBooneMexico Silt Loam
Mt. VernonLawrenceGerald Silt Loam

Accomplishments for 2000:

  • Field activities planned for this fall have been completed.
    • Fertility experiments have been planted alongside an existing statewide network of 7 wheat variety trials conducted by the University of Missouri. Two of the seven locations will not have fertility trials - one due to the wishes of the cooperating producer, and another that was fertilized with P and K in the first week of September before we contacted the cooperating producer.
    • Arrangements were made to have no P and K fertilizer applied to the remaining five experimental areas this fall.
    • P, K, and S treatments have been applied.
    • Deep soil samples have been taken and analyzed.
  • Experiments will be harvested in late June or early July 2001.


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