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The Mad Agriculture Journal

Published on

April 17, 2024

written by

Clark Harshbarger

photos by

Jane Cavagnero

Why sample our soils?

The soils under our management can be hard to observe. For one, we can only see the surface of the soil unless we take the time to disturb it. Secondly, agricultural soils are physically, biologically and chemically altered as a result of agriculture. So some of the inherent natural beauty has been disturbed. Historically, many forms of agriculture have depleted this vital natural resource as a trade off for a productive crop. Such as when considering fertility, the agronomic model of deplenish and replace was instituted. Another example of accepting a degraded resource as a result of agriculture, is the USDA-NRCS agronomic concept of the T factor. T factor stands for soil loss tolerance, which indicates that we can lose some amount of soil and still maintain productivity.

Regenerative agriculture challenges these concepts and asks our management to shift into a new paradigm about our soils. As a farmer or rancher, one typically heads to the field to sow, cultivate, and harvest. If raising livestock, it may be to check water, tag a calf, or to set up a new grazing break in a paddock. So when it’s time to head to the field to sample soil, it gives you an opportunity to put on a different hat, so to speak, to approach your fields with a new perspective. You are taking the intention to actually probe, unearth and observe one of life’s greatest mysteries, the soil under foot. Sampling your soils is an opportunity to learn. The NRCS soil health campaign used the slogan, “Dig a little, learn a lot”. So to the first reason and answer to the question, why sample your soil, is to look at your management, and see the results for yourself. 

The second reason is that customers want to support your progress. Organic markets and premiums are growing. But many of your customers will never visit your rural communities to purchase your commodities, so they look for labels and certifications in the box stores to provide them with consumer confidence. If a consumer packaged goods (CPG) company does not have the bandwidth to venture from their place of commerce to see the soils for themselves, then we must find ways to communicate the progress we are making to ensure their continued support from that side of the marketplace as well. Sampling our soils is one way to do this as part of several certification programs, including Regenerative Organic Certification (ROC).

The third and most traditional reason is to see what the nutrient availability is for the upcoming crops. Many parent materials can be absent in some of the essential nutrients that crops need to survive. Also, knowing that the nutrients are there but that they are bound up or locked up is equally important to help us choose the management practices to unlock them.

As slow as it sometimes may be, soils can improve their health. Every season, every place on the farm or ranch should have an opportunity to do so. There are no two ways about it. Every action on the farm has an impact on the land and greater ecosystem that the farm is a part of and sampling your soil with this perspective allows you to consider those outcomes in context to how you value your land and your business. So we sample to document the progress we are making and share it with our customers, brands, and farm team.

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So what is it that we are trying to learn and how can it help with our management of this precious natural resource?

Let’s take a quick look at the Regenerative Organic Certification (ROC), as it relates to soil sampling. When certifying with ROC, they are trying to allow for the land steward to take a three prong approach, one of which focuses on taking measurements of a few of the quantitative properties of the soil under management. They do this so the products purchased in the marketplace with this label, can help to insure to their customers that the lands where the ingredients/crops are being grown, are maintained and potentially building upon the health of their soils.

What is soil health? It is the ability for the soil ecosystem to function, so that it fosters habitat, food, and water for all living organisms, including the crops or forages being raised. The key measurements one can take and understanding the variability in your fields across the seasonality and heterogeneous soils (many variable soil types across a management unit) can be subtle and daunting. So do what you can, learn what you can with each sample and let us help you understand what you are seeing. Whether it’s looking at your lab test or understanding a picture of your soil structure, we can help!

As for improving your soil’s health, especially for organic farmers, cover cropping is essential. Farming with tractors has unintended consequences. Almost all tractor-scale farms have compaction and depletion of organic matter (OM). It is the nature of cultivation. To alleviate some of the negative impacts from soil compaction and depletion of OM, we use cover crops and potentially other amendments such as compost, manure, or rock minerals to help plants and soil organisms rebuild the soil structure. Plant and soil microbes work together providing a food source for the soil food web and in turn the microbes help to scavenge nutrients that were previously locked up or unavailable to the plant. Lastly, cover crops help to build residue, which can provide green manure when incorporated or can help protect the soil surface from erosion and soil temperature fluctuation.

ROC has released a sampling guideline that can be found here.

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Process for ROC Soil Sampling 

1. Find an accredited lab and ensure they are capable of performing all required ROC soil tests 2. Determine sampling locations and follow the ROC sampling protocol

3. Submit samples to the lab, record results, and identify areas for improvement 

4. Conduct field tests to measure progress 

5. Repeat and record the soil health lab and field tests every three years

Tips for successful sampling

  1. Create maps of land units and cropping systems, take pictures or use a GPS to capture approximate locations of your samples.

  2. Submit, process, and learn about your test. We can help you with this! If you have questions or want to bounce ideas back and forth please reach out to us.

  3. Find a record keeping system that works best for you. Electronic or file folder that helps to keep you organized. Sampling at the same time of year and generally in fields where you are incorporating new practices or crops can be a great place to get your money’s worth for the sampling.

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