Soil health a factor for weed, pest issues
August 27, 2013
This growing season, producers should take some time to assess the condition of their cropland soil resource say conservation professionals. Healthy soil is essential for plant growth and resilient to things that stress it, such as floods, drought, diseases and pests. Agronomic specialists with the Natural Resources Conservation Service (NRCS) are urging producers to take a look at the health of the soil in their own fields and pastures and get help if their soil isn't functioning as well as it should.
A top factor is organic matter because it holds nutrients and water for plant use and growth. NRCS Conservation Agronomist Jason Miller, Pierre, S.D. says "People can't do much about the type of their soil, but we can adjust management to increase the amount of organic matter in our soil." Increasing organic matter increases the soils' capacity for regulating plant available water along with other benefits.
A "healthy thing" is use of cover crops. However, Miller comments that corn-soybean rotations in a large portion of South Dakota can have challenges for incorporating successful cover crops into rotations since moisture and timing are limiting factors.
Bill Nelson is using cover crops for his cropland in Lake County, S.D. Because of the diversity in his cropping sequence, Nelson is seeing benefits of reduced soil compaction and improved nutrient uptake and management. "My fields are gentle, rolling hills typical of eastern South Dakota, but erosion is not happening here," says Nelson, "The residue and organic matter has greatly improved infiltration and soil water holding capacity."
Miller says other options for healthier soil are diversifying the plants covering the soil surface and keeping living roots in the soil as long as possible. "Producers, especially in eastern South Dakota, should be incorporating a small grain into the rotation that will then allow a successful cover crop to be incorporated behind the harvest," he explains. So, for example in a five-year rotation, Miller explains, "Producers can have a portion of their corn acres going into small grains (that contain a cover crop the previous year) and another portion going into soybean stubble. That small grain stubble allows better opportunity for establishing and getting the most benefit out of cover crops – using nutrients from the previous crops and increasing organic matter."
These practices build organic matter with positive effects on the biological life in the soil. "Active micro-organisms are what helps keep the health of the soil in balance," explains Eric Barsness, NRCS Conservation Agronomist, Brookings. In mid-July, he used a soil probe in Nelson's fields and found a rich, dark top soil about a foot deep that has resulted from the good cropping rotations based on soil condition, residue amounts, and use of cover crops. "The soil probe easily slid into Bill's soil because of the organic matter, good structure and aggregate stability," says Barsness.
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Nelson's crop rotation for this no-till field was oats (2011), cereal rye as a cover crop, soybeans (2012), and soybeans (2013). He put the cereal rye in with a fall seeding and when the snow came off, the rye was green. "That year (2012), we had a lot of spring rain and prevent plant acres around the county," Nelson explains. "The root system from that rye cover crop in my rotation held up the machinery up so we could get the soybeans planted."
The rye was terminated prior to it competing with the soybeans. This worked out well for Nelson, he says, "Then, that mat left from the rye root system and the above-ground residue was just what the fields needed." Additional residue can reduce weed pressure and helps fields hold moisture if the weather turns hot and dry.
Nelson used the rye in his rotation to help get to his goal of maintaining or increasing organic matter (OM) on his land to mimic levels found in natural prairie soils. Soil tests average 5.0 to 6.3 percent OM in Nelson's fields.
Another benefit he's seeing, Nelson told Barsness, is the 'break' from weed and pest problems. "With my rotation, I just don't have pest and weed issues such as corn root worm or Glyphosate-tolerant weeds," says Nelson.
"When a system gets out of balance, problems can pop-up. If you're seeing disease or pest issues with your crops," Miller says, "Maybe it's time to look past the symptoms and get to the source. Diversifying crop types and incorporating cover crops can help your soil to be more healthy." Contact Natural Resources Conservation Service for free on-site farm or ranch resource consultations. On the web, links to technical publications and guides are available at http://www.sd.nrcs.usda.gov/technical/CoverCrops.html.
A healthier soil means better moisture infiltration, retention or movement through the soil profile. "This is a major benefit in the long-term," says Miller. "By evaluating what their soil needs, producers can feel better about management decisions as they make adjustments to their operation." F