Farmers should consider no-till farming as the most important tool to prevent loss of soil moisture, especially during the current drought conditions in Iowa, according to Barb Stewart, state agronomist with the USDA's NRCS office in Iowa.
“Drought management is a top concern right now. With the drought conditions in Iowa, and across the Midwest, many producers are concerned about the next planting season,” she said. “And with the extremely early harvest, many producers have more time on their hands for soil tillage operations. NRCS is recommending farmers to use that time for something else more productive.”
Soil tillage reduces soil moisture in several ways. The first is reduced water infiltration. Tillage reduces water infiltration by breaking up the large pores in the soil structure, which act as large diameter pipelines for water to soak into the soil profile. Removing residue through tillage operations also leads to more soil erosion.
The eroded particles of soil can then clog the smaller pores or pipes, further preventing infiltration and causing more soil runoff.
“Iowa State University research shows that initial water infiltration rates are reduced from 5.67 inches/hour under no-till farming to 2.60 inches/hour under a soil tillage system,” said Stewart.
Other reasons to consider no-till farming as a great soil moisture management tool include:
• Every tillage pass can cause available plant moisture to drop .25 inch.
• Crop residue moderates soil temperatures, reducing soil moisture evaporation, especially in the top two inches.
• Corn stalks can help trap snow, which can add up to 2 inches of soil moisture after snow melt in the spring.
Stewart says many concerns farmers use to justify soil tillage are minimal this year.
“Under the dry conditions this season, soil compaction due to equipment traffic was minimal. Additionally, Gross’s Wilt was not an issue in 2012, so there is no need to use soil tillage to minimize risk for that disease,” she said.
Farmers concerned with soil moisture should visit their local NRCS office to discuss methods to help conserve and enhance the water holding capacity of their soils. Some of these practices include no-till, strip-till and cover crops.