Soil Health Changes in Three Years in Haywood County and Results of Rainfall Simulator at UT Experiment Station, Milan Tennessee
by Mike Hubbs, TACD Soil Health Specialist
On March 23, 2017, I had the opportunity to visit Bill Parker out on the Solomon Farm in Haywood County. This has been a farm that Bill has farmed the last three years. I had the opportunity to previously visit the farm in October of 2015. The two previous years of cover consisted of rye and crimson clover. This year was a five-way mix aerial seeded in early October. The stand was decent despite the drought, last Fall. Also, joining me on the visit were two farmers from Haywood County, a farmer from Lauderdale County, a Farmers Cooperative employee working Tipton and Lauderdale Counties, and NRCS employees from Brownsville, Tennessee, Joshua Choate, District Conservationist, and Melissa Rodriguez, Soil Conservationist. First of all, it was amazing the surface changes in the soil noted while digging. The soil was much fluffier or had better tilth. The structure had changed from a platy structure to much more granular and sub-angular structure. We like to see soil structure with the somewhat rounded shapes similar to marbles in a glass. They form soil-voids or pore space that leads to porosity. Porosity provides space for air and water movement most notably improved infiltration rates. We have noted anecdotal evidences for years with cover crops and no-till. We see it when comparing samples with the rainfall simulator. When compared to long-term no-till and vertical tillage and conventional tillage, samples with two to three years of history of cover crops and no-till perform better under rainfall simulator. They infiltrate better due to more cover and better aggregation due to more active soil biology. There is less run-off and erosion. Water is more efficiently infiltrated and utilized by plant roots. We also observed many earth worms in every shovel full of soil. Bill remarked that he had not seen many earthworms in the past. Earthworms is a macro biology indicator that soil health is improving. Earthworms, like other soil organisms, feed off other soil biology such as bacteria, fungi, nematodes, etc. as well as soil organic material from crop residues and cover crops. Lack of tillage is very favorable to earthworms. As time persists with no-till and cover crops, earthworms and other soil biology will increase. These organisms increase nutrient cycling, aggregation of soil, and movement of nutrients and soil organic matter both upward and downward. Earthworms are nature's tillers. Another indicator that was very observable was the strong earthy smell when digging. The sweet soil aroma was much less in 2015 compared to now. Earthy smell is from geosmin, an organic compound produced from actinomycetes, a colony growing bacteria. As soil is undisturbed and organic matter increases, soil earthy smell increases.