NRCS: What does healthy soil look like?
Ryan Summerlin June 14, 2012
Last week, Conservation Agronomist Jason Miller with the Natural Resources Conservation Service (NRCS), Pierre, SD, observed the soil quality at several fields at the Dakota Lakes Research Farm east of Pierre, SD.
The farm was purchased in the fall 1989 and all fields have been under a no-till farming system since 1990. World-renowned no-till advocate Dwayne Beck, South Dakota State University (SDSU), Pierre, has managed the Dakota Lakes Research Center since its inception.
The soil in this particular field is silt loam and will be irrigated. The pivot field has been in a corn-corn-broadleaf-wheat-broadleaf rotation for about 10 years. It was soybeans, pinto bean, and peas two years ago. In 2011, the field was winter wheat with a cover crop of hay millet, annual ryegrass (little) and volunteer wheat. As the second broadleaf in the sequence, soybeans are planted this year in the stubble of the winter wheat that was harvested with a stripper header.
With a simple shovelful of soil, Miller learned quite a bit about the field’s soil quality by looking at the soil’s color, number of pores and living organisms in the sample.
“Plants have a symbiotic relationship with the soil and organisms living in it,” said Miller. In this field, he explained that right at the soil surface, the biological activity is making the winter wheat residue decompose to become that precious organic matter which helps plants grow. Years of managing this field for the residue and to improve the soil quality has allowed the organic matter to build up and make the soil a darker color near the surface.
Miller said, “For an annual cropping situation, these photos show the Dakota Lakes Research Farm is a great example of managing the fields for the soil. In this cropland, it has taken 22 years to get the soil back to this healthy condition and it still can get better. In a short time, tillage destroys the health of soil – it takes a long time to rebuild.”
Tillage causes soil compaction that creates water infiltration and runoff problems, explains Miller.
“Because of the lack of tillage in this field, this soil has good structure that allows water to infiltrate through the macro pores,” he said.
A healthy soil profile has about 50 percent pore space for the movement of water and air – healthy soil holds water like a sponge.
“That means, if it is healthy, an acre can store a lot of water for the crop in just the upper few inches of soil,” he explained. This is important in the Dakotas where weather extremes can be a major factor whether a farmer achieves their production goals. The porosity of healthy soil helps it hold moisture better during dry cycles and drain more quickly when it is wet.
“It doesn’t happen overnight, but by increasing soil organic matter in their fields, farmers can better protect their yield,” said Miller. He pointed out that the healthy soil in this field at the Research Farm mimics the natural water infiltration cycle that leads to good water infiltration, less runoff, minimal erosion and reduced flooding and sedimentation.
“Increasing organic matter content means more productive soil,” Miller said. Organic matter increases the soil’s biological life, the number of soil pores, and soil permeability (the ability of soil to hold air and water for plant growth). “The worm castings we found by the base of the soybean plants are another indicator that the soil biology is working and healthy in this field,” Miller said. “Soil provides a biodiversity and productivity for the food we depend on.”
NRCS provides effective tools and expertise to assist farmers and ranchers manage with their natural resources. As they work to meet world demands for food and fiber production, hundreds of conservation farmers managing thousands of acres across South Dakota are using techniques such as precision farming, crop residue management, such as no-till systems, and cover crops to help their soil be more healthy on a microscopic level and ultimately more productive for the long term. Technical assistance for implementing conservation practices on cropland and rangeland is available from NRCS located at local USDA Service Centers.
“The challenge for farmers and other landowners is how best to feed the soil and farm sustainably to make a living now and in the future,” Miller said.