Avoid Gridlock

Published January 24, 2014 20:24

There’s a simple truth about precision ag and soil sampling: 2.5 acre (1 ha) grid sampling does not generate accurate lime application maps. This has been known since the start of precision ag. In October 1996, a Farm Industry News cover story ‘When Grids Don’t Fit’ reported this thoroughly, including examples of wide variations in pH within even 1 ac grids. Ag researchers documented this as well, including an Iowa State study that showed variations of 2 pH points within one acre. But without on-the-go sensing it wasn’t feasible to collect 10 samples per acre. The Veris pH Manager changes that. Now growers can have the improved lime accuracy they deserve.Overlaying 2.5 acre (1 ha) grids on a Veris pH Manager map shows the wide range of pH values within each grid. While the single sample in each grid cell may be accurate at the spot it’s taken, it is clearly wrong about the pH—and lime needed—in the rest of the grid.

P H PointsP H Over And Under

There are big dolla rs at stake…the difference in lime value between the grid sampled and the precise Veris pH map typically pays for the Veris mapping—and that’s just one use of the Veris data. At a $30/ton cost of lime, the accuracy of the Veris map is worth more than $20/acre

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