Digging In

The Dos and Don’ts of Soil Sampling

The Dos and Don’ts of Soil Sampling

By SHP Staff on Thursday, 14 May, 2020

Soil sampling can be a great step in the pursuit of healthier soils, but it is not always easy to get soil sampling right. The correct procedures yield the best data, and the best data helps farmers achieve the healthiest soil.

But how do you get the best data?

Dr. Nick Ward of Ward Laboratories, Inc. helped farmers understand how to best sample soils on their farm in an April 28 Soil Health Partnership (SHP) Soil Sessions webinar, “Quality in, quality out: the Dos and Don’ts of Soil Sampling.”

Most importantly, Dr. Ward reminds farmers that data is knowledge. The data available from proper soil sampling can impact future fertilizer applications, environmental compliance, diagnosis of problems, and overall sustainability. The question is not should I sample my soils, but how can I best sample my soils.

“You can’t make good decisions without data,” he said.

Farmers have numerous opportunities to make specific choices about how they will collect the soil data from their farms. Soil sample depths vary. Some farmers work from a 0-6” depth and some from a 0-8” depth. Dr. Ward teaches that “constant depth is the most critical thing when we’re out soil sampling.” 

Whatever depth you choose, just be sure to be consistent throughout the field and year over year to provide the best data. And when you are thinking about testing before or after tillage, just remember that consistent depth is paramount, so sample the same every year in a way that you feel most confident you are achieving a consistent depth.

Soil sample locations can vary. Many farmers chose to sample in a grid pattern, taking the samples where the lines of the grid overlap. This allows for the sampling of the same exact location over time in order to pinpoint changes in the soil, but some farmers choose to sample more heavily in certain zones or problem areas. Still, other farmers composite sample their fields, meaning they select the areas of the field to sample at random.

“Composite sampling should be doable for just about everybody,” Ward said. “Grid sampling is the most intensive practice, but it's going to give us our most robust data set to make decisions from.”

Your soil health strategy should inform the decisions you make for how and where to sample. The most important reminder is to always be consistent. 

How often should you sample? It will depend on your sampling strategy, says Ward.

“If you do something more intense like multiple zones or a grid sample, maybe doing that every 3-4 years would be a good practice.  But if you are not going to build a dense data set spatially across your field, maybe it is more important to take a dense data set in time.  So, that’s sampling a composite every year in different spots.”

This one-hour webinar will answer many questions and help farmers really nail down the sampling strategies that could work for their farms and soil health goals, as well as guide them with the return on investment for the effort. 

Check out other SHP Soil Sessions here