Information Management to Maximize Your Yields

Why Grid Sample?

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By Dr. R. M. Vanden Heuvel

Profit estimates for grid soil sampling using University fertilizer response curves indicate that it is a sound agronomic practice compared to “composite” soil sampling. Compositing individual samples taken across a field obscure or hide the “very low” and “low” testing areas of a field, where increased profits can be realized.

For instance, if a low test of 10 ppm P is mixed with high testing parts of a field, say 30 or 40 ppm, the resulting average would be high enough to result in a fertilizer recommendation at or near 0. This would not correct the low test area and yield in that area would be limited.

Iowa State University response data indicates that at 10 ppm P (Bray P1 test), about 9% of the yield is lost (see Figure 1 below). For a 200 bu/a potential yield, that’s 18 bu/a that will not be realized. This loss can be avoided if the low test areas are properly identified and managed correctly with the right amount of fertilizer.

The same principles apply to testing pH for lime and also K for correct potash applications.

So, grid sampling and a routine analysis gives you 3 chances (P, K, and pH) to improve your profitability!

To learn how you can get more from every acre, contact SciMax Solutions.