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Summer Annuals for Forage
by LuAnn Rolling, District Conservationist

Today I’d like to talk about a new system we’re exploring that uses summer annuals following a winter hardy cover crop.  The summer annuals are harvested for silage rather than alfalfa haylage or successive years of corn silage.  The advantages are allowing for more plant diversity to boost soil health, a reduced cost of production while maintaining a green growing root in the soil for as long as possible, and opening up new manure application and harvest windows. It also might be possible to harvest more total forage biomass with a summer annual mix compared to alfalfa.

The system would start with either rye or triticale after corn silage in the fall, as these two covers provide the greatest yield potential for forage the following spring.  In the spring the rye or triticale is chopped for silage at milk stage.  Triticale will head a least a week later than rye but harvest of the cover crops will be around the first of June.  After harvest there is a window for manure application and obtaining manure nutrients for the subsequent summer annual.  The recommend N rate for the annuals  is 120 to 160 units.

The annuals planted after the cover must have soil temperatures of approximately 65 degrees, which would be late May to early June. The common annuals would be sorghum, sorghum-sudan or hybrid sudangrass. Brown midrib (BMR) varieties provide higher digestibility and should be used if forage will be fed to lactating cattle. These are planted from 3/4 to 1-1/2 inches deep and approximately 50 lbs/acre.

Most corn planters need a special sorghum plate to handle the seed.  These annuals could be underplanted with rye grass and/or red clover for the winter cover once the annuals are harvested.  The annuals would be harvested three times, approximately late July, late August and late September.  The final harvest would only occur if there was the ryegrass, clover underseeding. Alternatively, annuals could be harvested in one or two cuttings, which will provide more tonnage but lower feed quality for dry cow or heifer rations.

Forage sorghum has approximately 90% of the TDN as corn silage and BMR sorghum can be similar to corn.  The cost of this system is $59/acre for sorghum and $71/acre for sorghum-sudan vs. $194/acre for corn silage.  The Dry matter yield is comparable with forage sorghums ranging from 8.3 to 9.4 tons/acre vs. corn silage at 8.5 tons/acre. The sorghum sudan yield is also similar to corn silage.

When you consider you also have the rye or triticale yield of approximately 1.9 ton/acre you are ahead in terms of DM yield with the summer annual system.  Producers can expect forage sorghum direct cut at soft dough to have about 10-12 percent protein – higher than corn silage, but lower than sorghum-sudan.

Following a summer annual/legume mix with corn provides the approximately 15% yield bump associated with first-year corn. This system breaks the pest cycles of continuous corn allowing for less pesticide use in this 2-year system.  It allows for less weed pressure than a mono-crop system and because of the use of covers and legumes nutrient needs are reduced.

One advantage to this system is the fall cover crop can be planted early enough (by mid. September) to provide optimal growth and produce more forage for a spring forage harvest. A second advantage is a two-year system with a corn silage-winter cover-summer annual rotation is easier to manage than a longer rotation such as four years corn followed by four years hay. It avoids the issues that can arise with alfalfa such as winter kill and seedings becoming thin and taken over by weeds, while providing the wonderful soil health benefits of a living root year-round and a great diversity of crops.  

Daniel Olson, a dairyman from Lena, Wisconsin, has switched to this system and says he has increased his per acre yields by 30%.  He stresses that this system provides the short-term benefits of increased profitability while also providing the longer-term benefits of soil health.

In his summer mix he uses BMR sorghum-sudan grass in addition to Italian ryegrass, hairy vetch, berseem clover, and red clover. He adds that it is important that a good variety of BMR sorghum-sudan is used to ensure good nutrition for his dairy ration. He likes the ryegrass and clover because for his late harvest they become the dominant forage and still provide excellent quality nutrition and provides him an over-winter cover crop. He then no-tills his corn into this the following spring.

He cautions that this system is aimed at quality forage and strongly encourages producers to plant high quality seed. He adds that many of the species will have a variety that is geared specifically to forage production (vs. seed production) and that is the variety that needs to be chosen.  He says his seed costs are not low but the benefits show in livestock production on this forage.

Olson tries to leave a 10-day window from the harvest of the rye or triticale before he plants his annual crop. He says this reduces the potential for allelopathy on any small seeded grasses.

He stresses that this two-year rotation serves to reduce the risks associated with our highly variable weather patterns: hot and dry or cold and wet, large rain events and prolonged dry periods. He is purposely building his mixes to be more resilient to these weather events, such as sorghum-sudan’s ability to withstand hot and dry conditions.  He adds that ryegrass and clover do well in cold and wet conditions.

We are looking for producers to try a trial of this system.  If you are interested please contact our office and we can discuss this new soil health cropping rotation.

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