Conservation Tillage Systems in the Southeast

Annie Dee, Dee River Ranch, Aliceville, Alabama

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Editor’s note: This case study was updated in 2018.

Annie Dee manages a 4,000-acre row-crop farm near the Alabama-Mississippi border in western Alabama. She farms with her brother Mike, her two sons Seth and Jesse, and their families. Dee River Ranch has been featured in many state and regional publications as an innovative and modern farm that utilizes precision agriculture, energy conservation and energy alternatives. Although the farm has some cattle and timber, the main commodities are corn and soybeans. Most of the farm lies in the Blackland Prairie region on mostly Sugarnoochee (fine, smectitic, thermic Chromic Epiaquerts) clays or Vaiden (very-fine, smectitic, thermic Aquic Dystruderts) clays. All row crops are planted on 30-inch beds or hips using no-till. Fields are hipped in the fall (beds are rebuilt) and planted to a cover crop, either a single species or a mixture. Beds are maintained as long as fields remain in good condition, sometimes for up to 10 years. Running the sprayer or combine in wet conditions may cause rutting that would prompt the Dees to rework the beds. Their systems are constantly being modified and improved to improve soil quality and productivity by building soil organic matter. 

What do you consider to be the biggest challenges in farming Blackland Prairie soils?

Managing moisture seems to be Dee’s biggest challenge. There seems to be either too much or not enough. She has worked hard trying to improve both surface and internal drainage, which is water entering and moving through the soil profile. Their largest field, the one they call the “Two Thousand Acre Field,” is a testament to improved surface drainage systems with a series of precision ditches designed to get excess water off the fields rapidly. Dee River Ranch also installed reservoirs and irrigation on more than 3,000 acres to help address this challenge. That has made a tremendous difference in the farm’s ability to produce excellent yields regardless of the rainfall. The first irrigation was installed in 2011 in two fields. That year, in one corn field, the irrigated yield averaged 185 bushels per acre while the non-irrigated yield averaged 28 bushels per acre. The average price the corn was sold for that year was $6.97. The difference in income for that field covered 75 percent of the total irrigation costs.

What conservation tillage techniques work best for you?

All crops are planted on beds that were made in the fall. These beds can be used for several years without disturbance. Cover crops are planted throughout the farm, and the corn or soybean crop is planted after killing the cover crop. The cover crop mixture depends on the crop following it and may include wheat, rye, oats, radishes, turnips, Austrian winter peas, rape, sunflowers and clover. They averaged more than 70 bushels per acre of wheat without any topdress nitrogen. Any tillage that must be done must be done in the fall, not the spring. Sometimes fall harvest may leave ruts in the field that requires some tillage to remove. All crops are planted in 30-inch rows. 

What are the biggest problems that you have encountered with conservation tillage techniques on Blackland Prairie soils?

Drainage, drainage and drainage, both surface and internal. Small-grain stubble and even corn stalks can wick moisture out of the soil causing it to dry out too fast. To combat this potential problem, all crops are harvested as close to the ground as possible so as little stubble as possible is left behind to wick moisture. This seems to help.

What are the biggest advantages, if any, of conservation tillage on these soils?

Preventing erosion, building soil organic matter and building soil fertility Additional benefits include increased cation exchange capacity, improved soil structure, and increased earthworms and microbial activity. With the increase in organic matter Dee has seen improvements in water-holding capacity, water absorption and penetration, along with fuel savings, equipment savings and labor savings. 

What are the biggest problems with conventional tillage (e.g., moldboard plowing, disking, chiseling, etc.)?

When it is too wet, you cannot get in the field anyway. When it is dry enough to till, tillage dries the soil out too much. Conventional tillage destroys the soil structure, causing compaction and reducing the pore space between soil particles. This reduces the organic matter as well as the water-holding capacity. It destroys earthworms and microbial activity in the soil, causing a decrease in overall soil health. Conventional tillage allows for an increase in soil erosion. When there is soil erosion, essential nutrients are lost to both the air and water, which causes pollution as well as a reduction in fertility.

What are the advantages of conventional tillage?

The main advantage of conventional tillage is the flexibility you have with weed control. This might decrease the need for some herbicides. 

Do you use subsoiling under the row? Why or why not?

No. The use of cover crops has eliminated the need for subsoiling. There are benefits to the soil from using a mixture of crops. They will each have different rooting depths. The turnips have mellowed the soil. The radishes have a very deep taproot that can break up hardpans. The oats, wheat and rye have long, deep, fibrous roots that go through any hardpan. Sunflowers have a deep taproot that will bring zinc up to the surface and make it available to the next crop.

Do you have any other comments or ideas about conservation tillage on Blackland Prairie soils, or ideas for future research?

We did not come with any knowledge of these soils, and we continue to learn. We have found that fieldwork must be done in the fall, if at all, and we must use cover crops. Our goal is to build soil organic matter using no-till.

We have tried to build soil fertility to the point where a lack of nutrients is not a limiting factor for the high populations of crops that we plant. We do not want fertility to be a limiting factor.

I would like to work with some scientists on the number and kind of microorganisms in the soil and to research if different cover crops affect the microbe populations.

Download the tables from Chapter 19.

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