Is It Time to Ditch Grid Soil Sampling or Shallow Soil Sampling?
An article discussing grid soil sampling "Is it Time to Ditch Grid Soil Sampling" appeared on FarmProgress.com on September 12, 2024. The article expert was discussing the problems with grid soil sampling and stating he felt that going to sampling by soil type gave more accurate test results. This discussion was very similar to the one I had with Marty Whitsitt, a GMS district manager from southwestern Indiana.
Marty had worked with some customers who had applied higher rates of calcium (Ca) lime, but then various results seemed problematic when comparing the soils and the liming rates. Marty's interpretation of the situation was that the Ca was moving down in different soil profiles at different speeds. This issue has been discussed in the agricultural literature about nutrient stratification with no-till farming. So Marty went to work on a couple of different fields doing soil tests at various depths. His results are summarized in Table 1.
Marty's experiment confirmed what Dr. Tiedjens had discussed in the early years of Growers Mineral, Corp. Tiedjens' point was that depth of rooting determined the plant's ability to withstand stress during the growing season. Therefore, Growers Mineral, Corp. has said that the proper level of the element Ca will give the soil more porosity to allow better root penetration. So, since 1955, Growers Mineral, Corp. has said soils sampled to 8 inches (top soil) do not tell the farmer if the plant can establish a deeper root zone. The farmer should sample both the top soil (0-8 inches) and the sub soil (8-16 inches).
In addition, knowing the Ca level at various depths will indicate the soil's ability to allow the microbiological population to rhizophagy in a larger area making more soil nutrients available to the growing crop. This allows the farmer to take advantage of the resources supplied by the environment. For the farmer, less expense means more ROI.
This is an excerpt from the Early Fall Growers Solution (2025) written by Jim Halbeisen, Director of Research.
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