West Tennessee Farmer Making a Difference in Soil Properties
Alex Johnson of Henderson County, Tennessee is our 43rd Profiles of Soil Health Heroes. On May 3, 2018, I had the privilege of spending some time visiting with Alex, his father, Mr. Johnson, and Meredith Crosby, NRCS District Conservationist, Henderson and Decatur Counties. Alex is a retired physician who also farmed his final 10 years of his medical career, which was quite challenging. He now farms full-time with his father. Alex became interested in changing farming practices to improve soil health by reading about nutrient management and soil health changes. Once he tried it; he was hooked and has been consistently growing covers for the last five years.
The Johnson farm is located in eastern Henderson county near Lexington, Tennessee. They farm upland loess fields (windblown silt) and creek and river bottoms. When we first went to the field for the interview for this article, Alex remarked that recent flooding on the Beech river showed muddy water coming off a nearby neighbor who uses tillage. In contrast, the water running off Alex's farm was clear. Many of the covers that we walked in were head high (6 feet) and some that were chest high (4.5 half feet). Alex told us that the cover crops are suppressing weeds, and he has reduced one herbicide spraying per year. He also uses IPM (Integrated Pest Management). He has reduced annual foliar fungicides. If scouting shows the need, he will apply them. He said that he is saving conservatively $34.00 per acre on herbicide and fungicide savings.
Alex grows predominantly soybeans due to economics. We discussed the agronomic advantages of crop rotation. He will receive some rotation effect from the multi species cover crops. Alex has grown five seasons of cover crops. He has adjusted his variety of soybeans to be earlier in order to plant his cover crops as early as possible. He grows a variety of group 3.5s, 3.8s - 3.9s. His latest planted varieties are 4.2s - 4.5s.
Alex soil tests every other year on each field. He does composite sampling. He applies phosphorus and potassium according to soil test results. Alex also maintains his pH according to soil test by applying lime as called for by soil test results. He has 15-inch precision row planters. He has added backing plates and plants both soybeans and his cover crops with precision planter on 15" rows. He plants cover crops fairly immediately after harvest. He planted his cover crops around the first to second weeks of September. Alex planted the remaining cover crops the second to third weeks of October. He plants his soybeans (green) in a rolled green cover and then applies herbicide quickly after planting. He uses a converted cultipactor that does not cut the soil as a roller/crimper. He also has modified some disks as row cleaners. He has a front-leading no-till coulter, row cleaners, double disk openers, followed by closing wheels on his planter.
Alex plants multi species cover crops. He plants cereal rye, triticale, bob oats, hairy vetch, Austrian winter peas, crimson clover, and tillage radishes up to the middle of September. His later plantings are the same mixtures with the exception of replacing turnips instead of tillage radishes. Radishes normally do not reach a significant size prior to winter killing if planted later than mid-September.
This past year he planted some cover crops the first week of September. During his second period of planting cover crops, the second week of September, the area received 10" of rain fall. His third period of planting cover crops were the second to third week of October. In general, the fields planted prior to and those planted at the same time as the flood were affected by the rain and saturated soils where the later plantings were not. We did not see significant stands of cereal rye in the early plantings. Text books and experience tell us that once established, cereal rye handles wet soils better than most other small grain species. However, it was significant that all species survived and were evident in all the early planted fields except cereal rye. We only saw a few plants of cereal rye in the early planted fields. Our speculation is that the cereal rye might have germinated earlier than other species in the very wet water-logged conditions and died. The other species were delayed in germinating and germinated later once the soils were no longer water logged. The radishes came up and died during the heavy freezes. We saw the distinct radish holes present. One of many advantages of multi species is if one specie does not survive, others will. The later plantings had evidence of all species surviving.
Now, I want to compare fields that have been in cover crops two years to fields in five years of cover crops. The fields that have been in five years of cover crops had remarkable soil changes. The soils had a strong, sweet, earthy smell. This is the result Actinomyces releasing an organic compound called geosmin. I dug in these fields and you could feel the shovel going into the soil easily with no apparent resistant layers. The soil had granular soil structure. We noticed more earth worms in the litter on top of surface as well and the rhizosphere, around the roots. We also noted many earthworm casts on soil surface. Finally, we noticed the previous soybean residue and last year's cover crops' residue decomposing quickly. All of the evidences suggest soil biology increasing in quantity and quality. Seeing the qualitative changes at Johnson farm makes me confident that his soils are improving based on active soil biology. Anecdotally, he reported clear water and less water running off. He is putting less inputs on his fields. His yields are improving.
The second series of fields have come out of an orchard and grass. The grass fields remained in grass until two years ago due to limitations. They are steeper or wetter. They disked the fields to get them smooth. They planted cover crops on these fields for two years. We saw much more residue from previous crops and previous cover crops indicating less soil biology activity. The soil biology had not have had enough time to increase in quantity and quality. There was much less of a earthy smell. It was there, but much weaker compared to fields that had been in cover for five years. There were earth worms present, but not much casts on soil surface. All fields had excellent cover. We did dig and noticed less granular soil structure. The structure had some evident weak platy structure, especially at three inches in depth indicating some compaction. The platy structure is from disking and just two years of covers. We also dug on the fringe of one of the fields where there was a small area where covers did not grow. It had no structure (no soil aggregates) and had no smell to it. As carbon continues to be produced by cover crops, and roots grow almost continuously, we should see remarkable improvements in soil structure in next two years.
All of these findings show the need to continue to increase carbon. That is carbon derived from annual crops and cover crops. This influx of increased carbon from plant material and roots feed the soil biology. If plants are present, carbon and soil biology will increase. Also, by increasing plant diversity, soil biology will diversity. Keeping covers present at all times, protect the food and shelter of soil biology as well as keeping a more constant environment. The cover acts as insulation, and it also prevents major moisture losses. Reducing or minimizing disturbances, such as no-tilling protects all of the benefits of crop growth, cover crop growth, and leaving covers on soil surfaces. The no-till prevents soil aggregates from being destroyed by tillage. Also, no-till preserves the soil biology habitat. With all of these principles being applied, soil health improves along with soil productivity and profits. The profits improve due to less inputs and increased productivity. The diversity and covers suppress weeds and lessen the buildup of diseases and insects.