Soil Sampling and Testing Issues For Nutrient Management: Certified Labs and Grid Sampling

Soil Sampling and Testing Issues For Nutrient Management: Certified Labs and Grid Sampling

Kevan Klingberg, UW Discovery Farms Program

Twice this winter I have run into snags helping individual producers walk their way into loading farm information into SNAP-Plus (nutrient management software) and beginning the journey into officially having all the right stuff for their nutrient management plan. They know soil testing is a key necessity, and had that service completed on their farm last fall. Their agronomist got that work done, processed the soil bags and field information sheets to their preferred lab, and soil test results are back!

The Issues:

1. One producer had all the correct field specific soil samples taken, but the soil test analysis lab utilized by the agronomist was not WDATCP certified. The methodology used for defining P soil test values was not UW-soil testing methodology. Also, the lab’s spreadsheet of final soil test values was not configured with the same sequence of titled columns that could import into SNAP-Plus. We manually reconfigured the spreadsheet, double checked our column-to-column accuracy, and did eventually import soil test values into SNAP-Plus. Officially, this plan will not meet the 590 standard, and soil test lab fees may not qualify as reimbursable within a nutrient management incentive project, all because samples were not sent to a certified lab.

2. Another producer was excited to have had his farm grid soil sampled. He owns and operates three different farms, each with 20+ fields. As we plugged the producer’s pre-loaded flash drive into the computer, it was quickly evident that soil samples had all been grouped together for each farm. This whole set of three farms had soil test values reported as three fields, each with 50+ samples. All of the individual soil tests were uniquely labeled and could be related back to a grid-point map provided by the agronomist. Yet, it took a number of hours to cross reference soil test values to sample locations and assign that information to individual fields. A significant amount of time was necessary to reconstruct this grid soil sampling project into something usable for a nutrient management plan. Grid sampling is completely acceptable for nutrient management planning, and this plan will meet the soil testing component of the 590 standard. Yet, it would have been helpful for the agronomist to develop a cross reference chart showing which soil samples were associated with individual fields.

Note to agronomy professionals: Make sure your soil sampling technical service and the soil testing end product does not become a limiting factor in developing nutrient management plans for your customers.

Note to producers: Make sure your agronomist knows that the soil sampling services you are buying need to meet specifications of the WI-NRCS Nutrient Management Standard (590).