Crop Update: Lack of moisture a concern for seeding lawns, planting fall crops

Posted: Sep. 8, 2011 9:25 am Updated: Nov. 28, 2014 2:17 pm

The lack of moisture has not only hurt existing plants, but is becoming a concern for those who wish to plant lawns as well as fall-seeded crops this fall.

It's difficult to consider seeding any type of crop now with soil moisture supplies so low. The risk is too great that if we get a rain on new seedlings and they begin the germination process, we'll need rain again in a few days to keep the soil from drying out and killing the seedlings.

Once the germination process begins, the soil can't be allowed to dry. And the soil is just so dry, that significant amounts of rain will be needed, several days apart.

Assuming we get some much needed moisture, and with the early harvest of corn, cover crops would provide some excellent benefits to many fields. Most years, aerial seeding of cover crops into standing corn or soybean has been the most common practice. The success of aerial seeding is entirely dependent upon rainfall. But since this year we're beginning to see early corn harvest, direct seeding is possible, and it has a much higher success rate since the seed is placed below the soil surface.

Cover crops have been used by many growers over the years to help provide a benefit to the soil. The benefits include erosion control, weed control, moisture management, nitrogen contribution, soil structure improvements and animal feed. And cover crops can be utilized by both commercial growers and the backyard gardener.

The grass cover crops that could be seeded now include cereal rye, annual rye, wheat and oats. Benefits of these grass crops include weed control for spring-seeded crops, grazing potential, nitrogen cycling, erosion control and improving soil structure. These grass crops have a better chance of success than do the other classes of covers seeded at this time of the year. Oats would be the choice if fall grazing is needed (they will not overwinter). Cereal rye can provide both fall and spring grazing, and it will also germinate late into the year (as late as November) in case seeding is delayed.

Annual rye is an excellent soil builder. Depending upon seeding date (the earlier the better), roots can extend down into the soil to 3-5 feet deep. The major positive aspects of annual rye include breaking up soil compaction layers and recycling of nutrients (nitrogen). Seed is relatively cheap as well.

Legume crops such as hairy vetch can provide nitrogen at a very reasonable cost. Unfortunately vetch needs to be seeded in August, so unless wheat stubbles are available, it becomes difficult to get this crop into the rotation. And it's not unrealistic to expect up to 100 pounds of nitrogen from this cover crop.

Brassica crops, such as turnips or radish, are excellent for establishing a quick cover to prevent weed infestations. They also can be used for grazing or for helping to improve soil structure and drainage. It may be a little late in the year to seed for this group to perform at its best. Usually an August seeding is preferred.

The grasses and brassicas will need a little nitrogen fertilizer to perform well. The legume will need an inoculant.

There are also negative aspects associated with cover crops, and one potential drawback would be moisture management in the spring. Some of the grass cover crops can draw huge amounts of soil moisture, and depending upon the year, that can either be positive or negative.



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