The Drought Monitor continued showing the marked improvement for all of central and even most of western Kansas. The dry conditions this past week should have allowed many producers to make progress with covering winter wheat fields. The six to ten day outlook (March 10 to 14) has above normal precipitation and temperatures which bodes well for the wheat crops continuing progress. Looking out eight to fourteen days (March 12 to 19) indicates above normal precipitation and well-above normal temperatures. The 30 day outlook is for equal chances of above or below normal temperatures and a coin flip for precipitation with the 90 day outlook basically near normal for both. Today, let’s continue discussing a hot topic in production agriculture – cover crops and their potential benefits.
• Benefit number one is, by keeping the soil covered with living vegetation and an active root system below ground, the virtual elimination of wind and water erosion. Keep in mind that even under the best of conditions it takes hundreds of years to produce an inch of topsoil. In addition to keeping soil in place, a cover crops keeps nutrients in the soil and minimizes nutrient loss in runoff or from moving into groundwater.
• Cover crops provide a nutrient and carbon source for soil microorganisms which increases biological activity, nutrient cycling, and builds up stable organic matter over time – humus. Increasing organic matter also helps by increasing the soils water and nutrient holding capacity while also decreasing a soil’s bulk density, improving soil structure, and improving soil tilth. The surface cover also aids in infiltration while below ground macroporosity is improved, especially when legumes are part of the cover crop mix and tillage is minimized.
• A cover crop with legumes, nitrogen fixing plant-bacteria association, such as peas, clovers, and vetches can contribute “free” nitrogen to the soil for succeeding crops. This can be significant depending on the amount of growth before termination.
• Weed control is also another benefit when things work out. Any actively growing crop is the best weed control and since cover crops are drilled, they can be an excellent way to smother out weeds and decrease the need for herbicides.
• Certain types of cover crops with aggressive taproots such as vetches and tillage radishes can be valuable in helping to break up hardpans and compacted layers in soils. This improves soil drainage, rooting depth for crops, and improves aeration.
• Typically to store moisture, producers in drier climates would fallow – leave the soil devoid of vegetation for a growing season to accumulate soil moisture for the next crop. Some fallow would be for a shorter period of time, say between wheat crops of fall-harvested crops. Initially, vegetation was controlled by tillage then herbicides became available so this could be accomplished chemically or by a combination of both methods. However, even under the best fallow technique water stored would only be around one-third of the precipitation received. Much research in places like northeast Colorado has found that except under the most severe drought, cover crops were more effective than fallow. In addition the biological activity was significantly enhanced.
Next week – the potential disadvantages and challenges of cover crops.
Dr. Victor L. Martin is the agriculture instructor/coordinator for Barton Community College. He can be reached at 620-792-9207, ext. 207.