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Study Results
Conclusions of a six-year study on long-term conservation tillage’ influence on soil quality, yield and returns in a corn-soybean rotation were discussed by Dr. Normie Buehring, Professor of Agronomy, Mississippi State University.
Photo by John LaRose, Jr.
Tips To Aid Farmers In Future Emerge From Long-Term Trials
BETTY VALLE GEGG-NAEGER
MidAmerica Farmer Grower
MEMPHIS, TENN.
The conclusions of a six-year study on long-term conservation tillage’ influence on soil quality, yield and returns in a corn-soybean rotation were presented by Dr. Normie Buehring, Professor of Agronomy, Mississippi State University, at the recent National Conservation Systems Cotton & Rice Conference here.
Evaluations took place on a Marietta loam soil in non-irrigated Northeast Mississippi, Verona, and on a Bosket/Dubbs silt loam irrigated at the Mississippi Delta, Stoneville environments. Crop management consisted of burning and not burning the corn residue and not burning the soybean residue since it was such a small amount.
Fall tillage systems were reduced Till (reshaped old beds when spring bed heights were less than three or four inches); Bed-roller; in-row subsoil-bed-roller (TerraTill®, one-pass implement supplied by Bigham Ag, Lubbock, Texas) and Disk twice plus TerraTill.
One finding was that burning corn crop residue had no effect on soil quality and yield. Another was that in the irrigated environment there were no soybean yield differences between tillage systems with a six-year average yield of 62 bu/a. However, in the non-irrigated environment, the TerraTill yield of 74 bu/a was greater than all other tillage systems.
“In both locations, irrigated and non-irrigated environments, the disk operations did not enhance yields or net returns,” Buehring said. “It also had a negative effect on the soil health.”
He went on to cite a post-doc study funded by the United Soybean Board on soil microbiology that found that the proteobacteria found in the soil destroys the organic matter in the ground in the disk situation.
“The disk treatment had more of this bacteria than the other tillage systems, and this bacteria destroys the organic matter in the soil,” said Buehring.
“So the corn crop residue management was not what we expected. At all locations, burning corn crop residue resulted in less ground cover and lower bed height, but at Verona the yield for soybeans in 2013 and corn in 2016 were better where we did not burn the crop residue,” he noted.
Another thing he cited is that when the crop residue is burned, the nitrogen and sulphur denied the soil bacteria these nutrients their need for them to function.
In the non-irrigated environment, the TerraTill yield and net returns were greater for both corn and soybeans; however, in the irrigated environment, there were no corn and soybean differences in yield or net returns between these tillage systems.
“There’s a slight difference numerically in the bed-roller treatment, which was better for corn in the irrigated environment. We did run a furrow plow between the rows so we could furrow irrigate,” he said.
He suggested that in the irrigated environment another look needs to be taken with the TerraTill in-row subsoiler using soil moisture sensors to determine whether an irrigation could be saved.
“We didn’t look at that because we didn’t have soil moisture sensors,” Buehring explained.
“What was interesting is the non-irrigated and irrigated environments results were the same as reported by Lyle Pringle for cotton at the Delta Station. He showed the same results with higher yields and higher returns in non-irrigated and there was no yield or return difference in the irrigated environment with an in-row subsoiler.”
Selective one-pass conservation tillage systems such as a TerraTill in a non-irrigated environment and Bed-roller (corn) and reduced till (soybeans) in an irrigated environment maximized returns and had a positive impact on soil health. The most aggressive tillage, disk twice plus TerraTill in both environments did not maximize returns and had a negative impact on soil health. ∆
BETTY VALLE GEGG-NAEGER: Senior Staff Writer, MidAmerica Farmer Grower
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