Soil Erosion and Soil Quality in Walsh County
By Rita H. Sveen
After a very wet spring with extreme rainfall events, things are not looking too bad out there for our crops, however estimates are still around 30% prevented plant acres in Walsh County. Many of these acres are not only due to excess moisture but to soil damage and loss. We had erosion, every kind of erosion. Even wind erosion was a problem before the rains hit. But that pales compared with the amount of soil lost to sheet and rilling from runoff on cropped fields. Gullies? Streambank erosion? – yes we had that too.
Wind Erosion Walsh Co. May 2013
Gully Erosion Walsh Co. May 2013
I would like to encourage Walsh County producers and ag advisors to take some time to educate yourself on your soil resource. What’s different from this event compared with previous events, is that today we know considerably more about soil biology then we did 5, 10 or 20 years ago. Agricultural research has proven soils are a living environment – in a healthy soil, there are about 6 billion microorganisms in one teaspoon!
Soils in the valley were traditionally left black in the fall because the high organic matter from the tall grass prairie and the high clay content naturally held more water in the soil. In cold climates like ours, it is the soil water that plays the largest role in the soil warming process in early spring. Therefore, blackening the field was thought to be the best way to warm the soil in the spring. However, tillage does have other negative consequences – we understand this much better today with advanced discoveries in microbiology. Consider the following tillage facts:
1. Tillage causes a burst of organic carbon to be released into the air. Aside from the atmospheric consequences, this is bad for the soil because that carbon is now lost as a food source for soil organisms. It’s difficult to get past the idea that tilling the soil is good – it must be good to mix in the oxygen and residue to “feed” the soil, right? But mixing the soil just makes it lazy. Soil organisms that engage in a long-term mineralization process are not advanced by tillage.
2. Tillage steel is cutting through the soil pore spaces created by earthworms and plant root channels. Macropores are essential for infiltration. Runoff and rain water flow through the macropores instead of running off – keeping your soil and inputs in place.
3. Tillage destroys fungal hyphae. Fungal hyphae are the thread-like structures used to gather resources and bind soil together into aggregates. Soil particles are aggregated and stabilized by organic “glues” exuded by the hyphae and plant roots. Soil biota help create aggregates and use them as habitat. Remember – the soil is a living food web; this web includes the plant root and its exchanges with nutrients and water. It all works together to improve the soils/plants natural ability to utilize water and nutrients. Loss of aggregation is visually apparent in eroded sediments.
Sheet and Rill Erosion Deposition 5/2013
4. Tillage and all other field traffic increases compaction, which restricts water and air movement, nutrient cycling, plant growth and biology.
5. Tillage causes the water table to rise, bringing salts to the surface.
Reduce your tillage with baby steps!
I’m not advocating the cold-turkey conversion of large tracts of cropland into no-till. It can take several years to improve your soil’s health. However, I think we can no longer ignore the loss of soil structure that has taken place over the last few decades. Long term healing of the soil is in order. Consider taking a baby step with one or more of the following:
1. Plant cover crops on prevent plant acres this year. Soil biota need growing plants to thrive - the diversity of species feeds a large variety of biota. Cover crops also remove excess moisture, which in turn reduces salinity.
2. Plant cover crops or grass on your water courses. Analyze your yields on these areas – is cropping really the best land use? Consider planting cover crops this year followed by alfalfa or grass. Safe, stable water conveyance is responsible soil stewardship that both landlord and operator should agree on. With the loss of CRP acreage in the county, it might be easier than you think to find someone that wants to hay these areas.
3. Try Strip till or no-till on a small plot of land – commit to this for at least 5 years. There are programs available to help offset the risk.
4. Improve the diversity of your rotation. Healthy soils needs plant diversity– the best rotations include all crop types: Warm and cool season grasses (ex. corn and wheat), and warm and cool season broadleaves (ex. soybeans and sugarbeets or cover crops).
5. Delay tillage after wheat harvest or plant cover crops. Following the combine with a disk, chisel or plow seems to be a source of pride – a black field right after harvest, but this practice is actually starving the soil. We know today that allowing regrowth or planting cover crops will feed the soil and therefore improve soil aggregation.
6. Increase your soil biology knowledge: There are multiple sources of informative videos, testimonials, and fact sheets available on YouTube and websites. One of the better ones I found that is specific to our climate is: Soil Quality: Managing Cool, Wet Soils (easily found with a web search or call the office for a copy).
Checkout the soil quality institute website: http://soils.usda.gov/sqi or for a more in-depth presentation, watch “The Role of Soil Biology in Improving Soil Quality” – on YouTube. Call our office for more information: 284-7466.