The U.S. Department of Agriculture ranks Wisconsin as No. 1 in the nation in acres of corn planted for use as silage.
“It’s a relatively efficient way of producing a high yield of digestible nutrients on a per-acre basis,” said Kevin Shelley, specialist with the Nutrient and Pest Management Program for the University of Wisconsin-Division of Extension.
Silage’s primary use is feed for cattle, particularly dairy cows. Because the corn-silage-making process removes the entire plant, newly harvested fields are often targeted for manure application.
“This creates a situation vulnerable for soil erosion and nutrient loss from runoff along with leaching of nitrates,” Shelley said.
One approach to the problem is to plant a winter cereal crop after corn-silage removal – for example winter rye and triticale.
“When established in September these crops can be utilized as an early-spring forage crop and a full-season crop can follow that,” he said. “This adds value to the cover crop.”
He emphasized the conservation and environmental-steward benefits of utilizing cover crops. Studies show a reduction in soil loss and the phosphorous index with a winter-rye-corn combination.
Shelley has been involved with cover-crop research since 2002. On-farm demonstrations have been essential to his work, he said, along with farmer-consultant focus-group interviews. One of the challenges has been to learn how to include rye or triticale in a dairy-cow lactation diet.
“Rye and triticale forage quality can be variable,” he said. “We generally see 1 to 3 tons of dry-matter yield per acre. I recommend harvesting at the boot stage. There’s an approach of leaving the crop to the soft dough stage, but according to farmers we interviewed most preferred to target that boot stage despite the narrow window of optimizing yield and quality. Triticale has a few-day-longer period from early to late boot stage, which gives it a slight advantage.”
The two crops lend themselves well to dairy-heifer feed.
“It provides an adequate nutrient profile for good growth in heifers,” he said. “It can be used to comprise up to one-third of forage dry matter in milk-cow rations. For most of (Wisconsin) harvesting occurs in the second to fourth week in May, which leaves time for a subsequent crop.”
In one study Shelley and his co-workers harvested rye in mid- to late May and immediately no-tilled corn into the rye stubble.
“As the rye starts to regrow we burn that down with an herbicide application,” Shelley said. “Some of the issues we have is seed slot closure when no-tilling corn in a wet year. Also the rye crowns occasionally make obtaining the proper corn-seed depth challenging.”
In terms of the economics of ryelage in a dairy-cow ration, Shelley summarized his work. He said it can replace alfalfa haylage when its relative feed value is at least 145. At a relative feed value of 145 and a ryelage content of one-third the dry-matter forage in a ration, milk production was maintained or showed an increase. He emphasized that wasn’t the case in average or poor-quality ryelage. He said by using best management practices the economic potential of cereal forages can be realized.
“We need to aim for a yield goal of 2 tons per acre,” he said. “To get that we’re probably going to need to plant in early September in the north. In the south of Wisconsin we can stretch it to the fourth week. If wet weather is an issue, consider strategies that allow you to plant before manure application.
“Try to avoid chopping at moisture levels above 70 percent. It helps to lay a wide flat windrow for drying.” H
Do a wet chemistry analysis to evaluate feed for mineral content because cereal silage can have increased levels of potassium. Producers should avoid feeding it to dry cows and close-up heifers because of the potentially increased potassium content.
Corn yields can be suppressed when following rye or triticale harvested as forage.
“You might want to consider other annual forage options following rye or triticale,” Shelley said. “There’s been a fair amount of interest in sorghum sudangrass.”
When alfalfa is planted after rye farmers should consider the possibility of allelopathic suppression of alfalfa seedlings.
Focus-group farms in his studies pointed out the additional value of cereal crops in terms of soil and water conservation, along with conditioning the soil and building soil health.
Badger Crop Connect is a crop-production webinar series developed for the 2020 growing season by the University of Wisconsin-Division of Extension crops and soils program. Bringing agronomists, crop consultants and farmers together, Badger Crop Connect provides bi-weekly updates on current issues. Shelley spoke Aug. 26 regarding “Cover Crops after Corn Silage for Spring Forage: Economics and the Environment.” Visit fyi.extension.wisc.edu/grain/badger-crop-connection for more information.