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Cover Crop part 2

Cover Crop part 2

County Agent News
Dan Folske
October 13, 2014

Cover Crops Continued

            Cover Crop Objectives:  Selection of species for cover crop mixes depends on your cover crop objectives and seed costs.

             Legumes in a mix can help provide nitrogen for the following crop by fixing atmospheric nitrogen into a form available to plants. Generally about half of the nitrogen in a legume plant will be available for use by a following crop within one or two months after terminating the cover crop (excluding months of frozen soils). 

            N scavenger crops are very good at taking up soil nitrates and reducing the amount of nitrogen which might have otherwise been lost to leaching. This can be especially important on sandy soils with high levels of precipitation. The nitrogen taken up by these scavenger crops is then cycled through the organic matter and released to your cash crops as the organic matter breaks down in the soil.

            Breaking hard pan or reducing soil compaction. Crops with tap roots are especially effective at breaking up compacted layers in the soil. Root crops like radishes, turnips, and sugar beets are very effective at opening the top soil and upper subsoil layers to allow water infiltration. Sunflowers have a deep taproot which helps breakup deeper compacted or less permeable soil structures. They are also excellent at taking up nitrogen which has leached below the rooting levels of shallower rooted crops.

             Reducing soil erosion can be a major consideration on steep slopes for prevention of water erosion or on soils where wind erosion is a problem. Crops with shallow fibrous root system can reduce erosion potential substantially. Crops with high carbon levels in the plant generally have longer lasting residues which can also be important in erosion protection.

             Increasing residue breakdown may be a consideration. Following high residue, high carbon content crops like wheat or durum planting cover crops with higher nitrogen levels in the residues may help speed up the breakdown of the high carbon residue.

             Fighting weeds- Fast germinating, fast growing cover crops can quickly provide a canopy which can slow the growth of undesirable weeds. Some cover crops such as rye and buckwheat also have the ability to suppress weed growth.

            Water management- Some cover crops have high water uptake and can help lower water levels to make planting the next cash crop easier. When lack of water is the problem you can choose low water use, high residue cover crops to reduce soil water losses from evaporation prior to seeding a fall cash crop.

             Grazing and forage- For a livestock producer, cover crops can be an important source of grazing or hay.

             Producers interested in trying cover crops should contact the USDA-NRCS office for information about possible cost sharing or program payments through programs like CSP and EQUIP. The signup deadline for this round of EQUIP funding is November 14th.

Next week I will talk about some specific cover crop species and their advantages and disadvantages.

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