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Cover Crops Planted During the Summer (07/19/18)

Although we have had a good planting season, some fields have not been seeded due to localized excessive rainfall.

Cover Crops Planted During the Summer

Although we have had a good planting season, some fields have not been seeded due to localized excessive rainfall. Producers may want to explore the benefits of planting a cover crop in fields yet to be seeded. Leguminous cover crops have the ability to fix nitrogen. Potential benefits of establishing a cover crop in a field include utilizing some of the excess moisture, building organic matter, suppressing weeds, increasing soil microorganisms, reducing water and wind erosion, and improving soil quality and tilth during the remainder of the growing season. Studies show it is better to have green vegetation growing on fields compared to leaving bare soil. Utilizing cover crops may result in higher yield potential for the subsequent main crops. 

Selecting a cover crop or mix of species depends greatly on the main objective of the grower. If nitrogen fixation is the main reason for growing a cover crop, then a legume (cowpea or soybean {photo 1}, dry bean, peas, lentil, clover, vetch are examples) should be used. The seed cost of legumes tends to be a little higher than non-legume small grain cover crops.

kandel

In areas of the field where the top soil salt concentration is relatively high, producers should consider crops with more tolerance to salinity. For example, barley is salt tolerant compared to some of the legume crops. Salt tolerant alfalfa or grass species are options where salt is an issue. However, if salt concentrations are too high, even so-called salt tolerant crops may not germinate and establish.

If fertilizer for the main crop was already applied, a brassica, grass (small grain), or brassica and grass mix can be utilized. These crops can scavenge residual N or pre-plant applied nutrients from the soil. When these scavenger cover crops are incorporated into the soil at the end of the season, part of the nutrients in the plants will become available for the subsequent main crop.

Cover crop selection and management should focus on maximizing both the above and belowground biomass, as well as encourage nutrient cycling.  Selection of a cover crop can include a ‘cocktail mixture’ of various crop species and may include, but is not limited to, turnips, radishes, sugarbeets, sunflower, legumes, small grains, sorghum or other grains.  One of the challenges of mid-summer seeding is the requirement for sufficient soil moisture, or timeliness of rainfall after seeding, for germination of the cover crop.  Using a drilling seeding method will provide better seed to soil contact than broadcast seeding followed by a harrowing.

Resource:  https://www.ag.ndsu.edu/plantsciences/research/forages/cover-crops

Hans Kandel

Extension Agronomist Broadleaf Crops

This site is supported in part by the Crop Protection and Pest Management Program [grant no. 2017-70006-27144/accession 1013592] from the USDA National Institute of Food and Agriculture. Any opinions, findings, conclusions, or recommendations expressed are those of the website author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture.

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