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Washington State University Extension

Irrigated Agriculture

infiltration

Protect the Soil Surface to Increase Water Infiltration

Posted April 28, 2014

If you want your soil to take water faster, protect the surface with crop residues. This was shown in a classic study from 1940.

F.L. Duley took a sandy loam, covered it with straw, and then applied a simulated rainfall to it for five hours at a rate higher than what it could take, resulting in runoff. He measured the rate of water entering the soil (infiltration) which settled to a nearly constant 1.2 inches per hour (click on graph below). After 40 minutes of this, he removed the straw. The infiltration rate of the now bare soil dropped rapidly, then leveled off at just 0.25″ per hour.

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Concentrate Organic Matter at Surface to Improve Soils

Posted April 15, 2014

Researchers are finding, in the US and in many other countries, that concentrating soil organic matter in the top 2″ promotes several aspects of soil health including nutrient cycling, resistance to erosion, and water infiltration and storage. They find that maintaining a high proportion of organic matter at the soil surface, relative to deeper layers, is more important than the total level of organic matter in a soil. Read more »

Using Crop Residues to get out of the Dammer Diking – Tillage Cycle

Posted March 25, 2014
Previous corn field disked to smooth over dammer diker holes, then planted. Note bare soil.

Previous corn field disked to smooth over dammer diker holes, then planted. Note bare soil.

Farmers wanting to maintain more crop residue cover on their fields are often prevented from doing so by previous dammer diking. While dammer diking controls runoff under center pivot systems, it also leaves large holes in the field, making it impossible to plant a following crop without tillage. The tillage required to smooth the soil surface for planting also buries most of the previous crop’s residues. The bare soil is then susceptible to surface crusting, poor infiltration, and runoff. To fix this, farmers dammer dike their fields, continuing the dammer-diking – tillage cycle. The way out of this cycle is to maintain a crop residue cover on the soil surface.  Read more »

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