Benefits of Annual Ryegrass as a Cover Crop
Annual Ryegrass, when used as a cover crop in the Midwest, can satisfy numerous farm objectives for growers:
Dan Towery, Ag Conservation Solutions
Natural hardpan (fraigpan) or manmade compaction prevent corn and soybean roots from getting deep moisture. These soils are found predominately in southern Ohio, Indiana, Illinois, Kentucky and Missouri. Annual Ryegrass creates macropores so corn and soybean roots can reach moisture under the hardpan. It will take approximately 4 years (4-6” fraigpan) of continuous no-till with annual ryegrass each year to achieve this. Incidentally, planting annual ryegrass for 2 years may be a substitute for running a ripper on compacted soils.
Who benefits? Certainly those growers already doing no-till as well as those moving to no-till from conventional tillage.
Annual ryegrass provides quick ground cover after harvesting corn silage or seed corn which provides good erosion control. The earlier harvest and lack of residue makes these good candidates for use of annual ryegrass.
The high price of nitrogen has growers looking for way to be more efficient. Using annual ryegrass may provide 60-80 lbs/ac of nitrogen. This alone could more than pay for the cost of the seed and planting it. In addition, after several more years, Phosphorus may become available as P2 is transformed to P1.
Growers applying manure are being required to apply manure in a more environmentally friendly fashion. Using annual ryegrass could help keep the nitrogen in the soil profile and available for the crop the following year.
In addition to improving fertility, annual ryegrass produces biomass that will increase the soil organic matter and fertility after the cover crop is burned down in the spring.
Quicker Transition to No-Till
When a grower changes to no-till or acquires a farm that is new to no-till, it commonly takes approximately 5 years for key soil properties (aggregate stability, organic matter, increased infiltration, pore space, fungi, etc) to occur. Adding annual ryegrass may reduce this transition period by half.
Annual ryegrass is a vigorous seedling that quickly forms a cover to compete with winter annual weeds.
Increased Water Infiltration
The extensive and deep root system that annual ryegrass develops provides pathways for increased water infiltration.
Soybean Cyst Control
Soybean cyst nematodes results in lower soybean yield. Preliminary research studies indicate that if annual ryegrass can be planted early enough so that it is established for at least 40 days with the soil temperature about 50 degrees, then cyst eggs hatch in the fall. This results in a very low count, if not elimination, of this pest the following year. Fields in the southern half of Illinois, Indiana, Ohio, and Missouri are potential candidates since the odds of meeting the 40 days above 50 degrees requirement are likely.
Growers who plant after wheat or corn silage may be able to take a cutting of haylage in the fall and possibly in the spring and then no-till into the annual ryegrass. Growers in southern Ohio, Indiana Illinois, Kentucky and Missouri may be able to graze the annual ryegrass over winter or take a cutting of haylage in the spring.