An Afternoon Spent Soil Sampling at Rodale Institute


By Jesse Barrett – Rodale Institute, Organic Allentown Program Manager

When you ask a person, “What is organic agriculture?” you will probably get a different response from each person that you ask. Most people respond to the question with answers concerning how the crops are grown with no GMOs and no use of chemical inputs such as chemical fertilizers, pesticides and herbicides. Sometimes you can see the worry in their expression as they struggle to find a simple and direct way to explain organic agriculture. But the good news is that there is a simple definition. Organic agriculture is best defined as a method of farming where the farmer is as concerned about growing and promoting the health of their soil as much as the crops that are grown from it. Regenerating the health of our soils is the primary focus of organic agriculture, but how would one definitively know the health of their soil?

photo-nov-09-3-31-46-pmSoil sampling is the best tool that both conventional and organic growers have at their disposal to truly learn about the health of their soil. Rodale Institute’s Communications team spent the afternoon assisting Tara Caton, Research Technician, and Emily Lesher, Research Intern, with sampling the soil in the fields of the longest running experiment at Rodale Institute, the Farming Systems Trial (FST). We met Tara and Emily in the FST fields, and were given a little background information on Rodale Institute’s premiere experiment. FST has been actively operating for the last thirty-six years, and is the longest running comparative experiment between plots that are maintained through different farming systems such as organic manure, organic legume (nitrogen-fixing cover crops), conventional synthetic and no-till systems. The soil samples taken from these fields are utilized to build the data that the FST experiment has been accumulating for over the past three decades. And, yes, there are soil samples from every year catalogued at Rodale Institute, which paint a thorough picture of how organic agriculture affectively builds the health of soil over each year.

photo-nov-08-9-03-08-amThe next step of our day was to learn how to sample soil. We were given soil probes, which are hollow metal tubes designed to be thrust into the ground and twisted. The twisting motion traps the soil sample in the tube, and the person sampling pulls the probe from the soil bring the sample out of the ground. Tara and Emily joked about how people like different ways of physically extracting the samples. There are three major techniques: the spear, the stomp and the pogo-stick. All are equally effective, depending on where the individual sampler feels they have more body strength. The probes were also marked with tape to assist in guiding the sampler on the desired depth. Rodale Institute conducts two types of soil sampling, and they are deep-core and surface sampling. We were assisting with surface samples with a depth range of zero to twenty centimeters. Tara and Emily requested the random sampling of multiple fields in FST with ten samples per field. Extracted samples were placed in large, plastic bags that were marked with information about the sample such as date, field and depth. Next step, prepare the soil samples for analysis.

Tara also explained some of the qualities of the soil that sampling defines. The samples are tested for soil chemistry, amount of organic matter, nutrient content and respiration. As for soil chemistry, Rodale Institute is especially interested in the amount of carbon that is sequestered in the organic systems. eHe Healthy soil acts as a carbon sink, captures the carbon from the atmosphere, and thereby mitigating climate change. Organic matter is higher in the fields that utilized organic systems, which returns macro and micro nutrients to the soil. Respiration is a way that the research team measures how much biological activity is in the soil. Our soils are alive with both micro and macro biology, and organic systems promote soil that is teeming with life from bacteria, to fungi and larger life forms like worms.

photo-nov-08Soil sampling is the only way that growers can gain a complete picture of what contained in their soils. The practice of sampling soil is obviously very important for both conventional and organic farmers, but it should not be ignored by home gardeners either. For a marginal cost, usually less than twenty dollars, home growers purchase home soil sample kits. Samples can be sent to Penn State Extension, Cornell and Ohio State Universities. The price of their analysis can vary depending on how complete of a report you would like to run, but the basic analysis usually can be purchased for around ten dollars. Tara suggested testing your soil at least on a yearly basis. However, for the best results testing pre and post-harvest would give you a more accurate picture.

For a more in depth description of Rodale Institute’s Farming System Trial, visit rodaleinstitute.org/our-work/farming-systems-trial/.

 

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