Consider Winter Rye Forage After Corn Silage

By Jane Fyksen, Crops Editor
Thursday, September 20, 2007 9:02 AM CDT

More Wisconsin producers are growing more acres of corn silage. Planting winter cereal rye after corn silage has soil conservation and nutrient management benefits, not to mention an early-season forage the following spring. The UW Nutrient and Pest Management Program is promoting this over-winter crop, says UW NPM program outreach educator Kevin Shelley in Madison.

The UW has been gleaning insights on winter rye from research over the last several years at the Arlington and Lancaster research stations and at a Janesville project. Taking a long, hard look at winter rye with Shelley are Jim Stute with UW-Extension in Rock County; Dwight Mueller at the Arlington station and Tim Wood at Lancaster.

In addition to the benefits above, winter rye also suppresses weeds and serves as a hedge against a forage shortfall due to drought or alfalfa winterkill. What's more, fall-planted rye won't delay planting of another crop come spring. Rye harvested at boot will produce 2 to 3 tons of dry matter (DM) per acre with an average Relative Feed Quality (RFQ) of 180 (in a range of 149 to 205, based on UW work). Other average quality parameters are: 16.2 percent crude protein, 27.6 percent ADF, 52.2 percent NDF, 0.39 percent phosphorus, 3.05 percent potassium.

Expect nutrient removals on a DM basis from rye harvested at boot like these: Nitrogen, 121 pounds per acre (range of 69 to 178), phosphate, 42 pounds (29 to 71), and potash, 178 pounds (110 to 344).

This quartet of experts suggest rye be planted as soon after corn silage harvest as possible. In southern Wisconsin, getting it in by mid to late September producers more tonnage, and the rye tends to mature slightly earlier the following spring. Yield potential, though, doesn't begin to drop off until around Oct. 10. Later planting means less soil cover and protection over winter. Still, rye is a fast-grower in the spring, and even with later October planting, it'll yield acceptably.

The recommended seeding rate is 90 to 112 pounds per acre. Farmers may have seen 60 to 90 pounds recommended; that's for grain production - not forage. If you're planting later than Oct. 10, going with a rate beyond 112 pounds (two bushels) may help with yield and increase over-winter soil coverage.

As with oats, boot-stage harvest best balances yield and quality. That's just before the seed head emerges, when it can be felt near the top of the leaf whorl within the sheath of the flag leaf. Beware that forage quality drops quickly beyond boot - like four to five RFQ points a day. Timely harvest is crucial with this cover crop. What's more, they warn, boot stage only lasts a few days. Get at it well before the flag leaf splits and heads begin to show.

In southern Wisconsin, where the UW work has been done on winter rye, boot generally occurs by mid-May. To hedge against rainy weather at that time of year, these crop experts suggest harvesting rye early if a long rainy period is in the forecast.

If you can't harvest at boot, consider terminating the crop with herbicide. You'll already have gotten conservation, N uptake and weed suppression benefits. Use glyphosate or paraquat at standard burndown rates.

Rye likes N and reciprocates with more yield and protein. The economically optimal N rate is 40 to 60 pounds per acre with fertilizer, but closer to 80 pounds of creditable N per acre if it's all from manure and/or previous legume. N should be applied in early spring before rapid growth is initiated. Going beyond 80 pounds of N reduces yield and causes lodging. If you're only using the rye as a cover crop, no additional N is necessary.

P and K is typically sufficient on most farms for rye, with having to add more.

Producers are warned that rye forage can put excessive pressure on silo bags, causing them to fail. Don't overfill and watch for tears along the top of the bag.

Rye forage can be high in K, which may limit its use in dairy rations, due to concerns about milk fever. The NRC tags it with an average K level of 3.34 percent - higher than most common forages including alfalfa. The Catch 22 is that its quality better suited for dry cows if it's harvested on the late side. Rye, though, is a "luxury feed" of K. Farms with elevated soil-test K levels may experience excessive uptake; as high as 4.37 percent forage K has been seen in rye grown on soils over 300 parts per million K in Wisconsin. Producers should test rye forage for K.

As noted, rye can be real good for some farms' nutrient management plans. It takes up nutrients late fall and early spring when leaching can occur. Taking off rye forage, followed by another crop, significantly increases annual nutrient removal from soil. The NMP benefits are for both N and P, or just N, depending on whether the rye is harvested or not. The estimated removal of N by rye forage is 52 pounds per ton of DM.

Rye can significantly reduce soil nitrate following fall manure applications - even if rye isn't harvested. Groundwater quality is protected when manure applications are heavy. According to UW research, soil nitrate was 100 pounds per acre in the spring at rye harvest (following 40 tons of dairy manure per acre fall-applied), versus almost 200 pounds of nitrate in the soil profile without the rye.

Rye forage also removes P and K - 18 pounds of phosphate per ton of DM and 80 pounds of potash. Coupled with the summer crop's nutrient removal, on a yearly basis, removal is increased significantly and your nutrient management plan benefits.

Rye can draw down soil test P in fields where it's excessive and where applications may otherwise be prohibited under a P-based plan and rules. Rye can also be used to maintain soil test levels under higher rates of application (by matching application with removal).

There are a few other things to know about winter rye, say Shelley, Stute, Mueller and Wood. Watch the corn herbicide rotation interval. Rye might be listed specifically or grouped with "other crops." Many require a four-month interval or more from application to rye planting.

Winter rye seed might be difficult to source. Check availablility well in advance. Certified seed of Hancock and Spooner varieties are available, along with uncertified seed. All have performed pretty much the same in Wisconsin trials.

Manure applications after corn silage can interfere with rye planting. It's possible to apply manure after the rye has emerged, but only with liquid manure under 10 percent solids and at rates of 5,000 to 7,000 gallons or less. Semi-solid manure applied to rye early smothers seedlings and cuts into yield.

Corn, soybeans or alfalfa can be planted after a rye forage harvest. No-tilling RR corn or beans into rye stubble will allow for a convenient later glyphosate application to control rye regrowth and weeds. Otherwise, fairly aggressive tillage and post-emergence weed control is needed to control rye.

Arlington research suggests soybeans or alfalfa may be better choices than corn to follow rye. Corn showed yield reductions (127 bushels versus 140, respectively, for three-year average yields), while soybean yields didn't change much.

This Nutrient and Pest Management Program team has more detail about this relatively newcomer crop to Wisconsin in a new publication, "Planting Winter Rye After Corn silage: Managing for Forage." It can be had by calling 800-994-5853 or on line at the UW-NPM's website at http://ipcm.wisc.edu.

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