Building Better Roots with Annual Ryegrass
Dan Towery – Ag Conservation Solutions
Annual Ryegrass as a cover crop in the Midwest has seven different potential benefits for growers depending on their objectives. Growers may use annual ryegrass primarily for one objective but usually there are several other benefits associated with its use. Potential benefits include the following:
- Breaking up natural hardpan (fraigpan) or manmade compaction – Soils with natural hardpans or fragipans would predominately be found in Southern Ohio, Indiana, Illinois, Kentucky and Missouri. Annual ryegrass roots have been found to grow through this restricted layer when planted every fall for approximately 4 years (4-6” fraigpan) and combined with continuous no-till. The annual ryegrass roots create macropores which corn and soybean roots can then follow and reach the moisture under this restricted layer (which is normally not available). In a dry year this will enable significantly higher yields due to the additional moisture being available. In addition, planting annual ryegrass for 2 years may be a substitute for running a ripper on soils compacted by tillage or implement traffic. Actual results are dependent on soil type.
- Improving nutrient cycling, primarily nitrogen – The high price of Nitrogen has growers looking for way to be more efficient. Using annual ryegrass may provide 30-60 lbs/ac or more of nitrogen for the following crop. This alone could more than pay for the cost of the seed. Adding annual ryegrass to continuous no-till will also increase the rate organic matter increases in the soil. An increase in organic matter will also result in more nitrogen being available. In addition, after several years more phosphorus may become available as unavailable phosphorus (P2) is transformed to available phosphorus (P1).
- Improving nutrient cycling after manure application – Growers applying manure are being required to apply manure in a more environmental fashion. Annual ryegrass helps keep the nitrogen in the soil profile and available for the crop the following year (percentage of nitrogen actually available will depend on a number of factors). Initial trials have documented 500 to 700 lbs of N being taken up by the annual ryegrass with 70-80% possibly being available the following year. Growers who empty their pits or lagoons after wheat harvest or after corn silage are prime candidates for adding annual ryegrass to their manure management system.
- Ground cover after harvesting corn silage, seed corn, or vegetables – The earlier harvest and lack of residue makes annual ryegrass a good fit after corn silage, seed corn, and vegetables. It will provide cover to reduce erosion, break up compaction, and scavenge nitrogen in the soil profile.
- Soybean cyst nematodes results in lower soybean yield – Preliminary results 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 soybean cyst eggs hatch in the fall. This then results in a very low, 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 much more likely. Additional research is needed.
- Speeding up the soil’s transition to continuous 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 change. Adding annual ryegrass as a cover crop may reduce this transition period by half (actual results will depend on soil type).
- Utilize annual ryegrass as a forage and a cover crop. 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. This will provide high quality forage (1.5 to 4 tons/ac and over 22% protein). 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.