Monday, September 12, 2011

Winter rye: a versatile cover crop

Ajay Nair
Department of Horticulture, Iowa State University

Winter rye (Secale cereale L.) is one of the most popular and versatile cover crop in many regions of United States. Because of its cold hardiness winter rye is the only cover crop that can be planted as late as in November or even December in the Midwest and the Northeast. Rye has a wide seeding range from 60-120lb/A and is relatively less expensive ($12-15 for a 50 lb bag). Winter rye can also be grown in mixtures with a legume such as hairy vetch. When growing a winter rye and legume mixture, the rate of winter rye seeding should be reduced to half of its original seeding rate.

Rye cover crop in spring
Cover crop being mowed

Once established in the late fall, rye roots hold the soil protecting it from erosion and compaction due to rains in the fall and spring. The above ground biomass helps captures residual nitrogen that would have otherwise leached away. Rapid growth of rye plant shades the ground and suppresses growth of winter weeds.   Winter rye and its residues release plant growth-inhibiting substances called alleclochemicals that are active against suppressing weeds such as pigweeds, lambsquarters, purslane, and crabgrass. A fast-growing rye cover crop competes strongly for light, nutrients, moisture, and space, and can thereby suppress weed growth and development. As the temperatures increase in the spring, rye produces large biomass which is generally mowed and incorporated into the soil. This stimulates soil microorganisms and adds soil organic matter. Also, because of its potential to produce large biomass, rye has been successfully used in no-till cropping systems, especially for vegetables such as pumpkins and squashes.  
All of these characteristics make winter rye an excellent cover crop for our region and depending upon their rotation plans growers should consider incorporating rye into their production systems. To summarize, benefits of rye cover crop include:
1) Reduction in soil erosion
2) Weed suppression
3) Improvements in soil physical, chemical, and biological properties
4) Recycling of nitrogen and other nutrients
5) Enhancement of cropping system diversity
6) Habitat for beneficial insects
7) Use in no-till production systems

Thursday, September 1, 2011

Its time to cover our soil !

Ajay Nair
Department of Horticulture, Iowa State University

When it comes to reducing soil erosion, suppressing weeds, improving soil fertility and health, increasing water holding capacity, and soil organic matter, there is nothing that comes to mind other than COVER CROPS. Cover crops are crops that are grown to cover bare soil between cash crop plantings, however its impact on biological, chemical, and physical parameters of a production system is far reaching and substantial. Cover cropping provides numerous benefits (mentioned above) which make them attractive and useful in any cropping system.  As we are inching towards our fall season, some overwintering cover crops that could be fall planted in Iowa include winter rye, hairy vetch, oats, winter wheat, and some clovers. Although there are a number of choices, growers should chose cover crops that would fit their cropping system and addresses a specific need or problem. If addition of organic matter and weed suppression is a priority, then winter rye would be a better choice. Leguminous cover crop for example  hairy vetch could be utilized when addition nitrogen is the primary goal.

Our lab in the Department of Horticulture at Iowa State University recently set up a cover crop study focusing on cover crop combinations that would enhance nutrient cycling, soil biology & quality,  and improve vegetable production.We are testing winter rye and some other cover crops, individually and in combinations, to develop cover cropping systems that can be utilized for vegetable production in Iowa.  Some aspects of interest include weed suppression, nitrogen management, and crop production. Cover crops seeds were recently broadcasted, incorporated and irrigated (pictures above).