2008 Joint Annual Meeting (5-9 Oct. 2008): Grid Sampling or Conventional Sampling to Guide Site Specific Recommendations of Phosphorus and Potassium in Small Crop Fields in West Virginia.
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770-2 Grid Sampling or Conventional Sampling to Guide Site Specific Recommendations of Phosphorus and Potassium in Small Crop Fields in West Virginia.



Wednesday, 8 October 2008: 1:30 PM
George R. Brown Convention Center, 371A
Eugenia Pena-Yewtukhiw, Division of Plant and Soil Sciences, West Virginia University, Davis College of Agrictulture, Forestry and Consumer Sciences, 1104 Agricultural Sciences Building Evansdale Dr, Morgantown, WV 26506-6108, Edward B. Rayburn, West Virginia University Extension Service, West Virginia University, Agricultural Sciences Building Evansdale Dr, PO Box 6108, Morgantown, WV 26506-6108, Craig W. Yohn, West Virginia University Extension Service, West Virginia University, County Extension Agent for Agriculture and Natural Resources, Jefferson County, 1948 Wiltshire Road, Suite 3, Kearneysville, WV 25430 and Tim Fullen, Private consultant Fullen Fertilizer, Fullen Fertilizer Co, Inc, PO Box 172, Union, WV 24983
Grid sampling cause significant nutrient redistribution (less in some field areas, more in others), relative to conventional (single composite for entire field) sampling.

We hypothesize that not all the fields need to be grid sampled.

Materials and Methods

33 fields between 5 and 47 acres where sampled (average size 21 acres)

The grid cell size varies between 1 and 2.25 acres (average of 1.8 acres)

33 fields with 3 to 16 cells (average of 10 cells/field).

Soil samples were analyzed for soil test P (STP) and soil test K (STK) by Mehlich I extraction; “Field-average” STP and STK was independently acquired by conventional soil sampling (single composite field sample).

Assumptions: 1 to 2.25 acre grid size may not capture all management-relevant variation

Conclusions:

Grid sampling was usually beneficial, but pre-sampling to identify candidate fields is useful.

Grid sampling tends to benefit most fields as nutrient addition/nutrient removal brings average STP and STK values close to recommendation thresholds.

See more of: Measurement and Management of Soil Potassium and Phosphorus Availability
See more of: S08 Nutrient Management & Soil & Plant Analysis