Opportunity for small fields difficult to plant and harvest or to manage along creeks, pastures
By Denise Schwab and Erika Lundy-Woolfolk
Ensuring adequate forage for the cow herd is a never-ending challenge for most producers and is becoming even more difficult as land prices in the Midwest have continued to increase. While cattlemen are challenged with running more cows on fewer acres, good pasture management, rotational grazing and fertility can help optimize forage availability, but often isn’t enough to maintain the cow herd especially in dry years.
While many have looked to utilizing winter annual forages to extend the grazing season, some have expanded the use of summer annuals to fill summer slump grazing gaps too.
This isn’t really a new concept – our grand and great-grand parents were using annual forages. However, it is new to this generation of producers as we rely heavily on perennial forages. While perennial forages are probably our most economical feed source, annual forages are an affordable option that can help to fill some of the current gaps in grazing perennial forages.
Our Iowa State University Extension beef team started demonstration and research projects on grazing cover crops (winter annuals) over a decade ago with projects on both fall/winter and spring grazing. In the last five years, we’ve added work on summer annuals as well. First, I’ll share some of the research projects and results we’ve seen, and then I’ll discuss how this can be used to fill grazing gaps.
ResearchOur initial winter annual projects focused on field days where producers have successfully grazed cover crops, however since we are harvesting the forage we call them winter annuals. It’s the same crop except cover crops are intended to protect the soil and provide environmental benefits while winter annuals are intended to be grazed or harvested for feed.
This led to research plots to answer the question of how much forage can we produce from winter annual forages in Iowa. Erika Lundy-Woolfolk established winter annual forage plots at the ISU Armstrong, Neely-Kinyon and McNay Research Farms in the fall of 2019 with five forage species and two rates of nitrogen1,2. The dry matter yield results were lower than expected, and barley did not overwinter in these southern Iowa plots. Other demonstration plots and on-farm experiences showed much higher winter annual yields.
One of the comments I often hear in northern Iowa is that the growing season is too short to effectively grow winter annual grasses, so we are currently testing that theory at the ISU Northeast Research Farm in Nashua, Iowa. Our major objective was to look at the winter annual/summer annual rotation and measure how much forage could be produced on an acre of ground. We also wanted to focus on species that fit well into grazing systems, not just mechanically harvested systems. Two of the three years of this project are completed, with the third year of winter annuals seeded.
Four winter annual species with two nitrogen rates were established on Oct. 30, 2020, and Oct. 4, 2021 with four replications of each treatment. First year treatments include Elbon cereal rye, Willow Creek forage winter wheat, Flex 719 Brand triticale and Thompson hard red winter wheat, each with and without 50 pounds(lb) nitrogen (N) fertilizer per acre (ac.). Second year treatments included KWS Progas cereal rye, Hazlet cereal rye, Triticale and Thompson hard red winter wheat, each with and without 50lb N. Each were seeded at a target rate of 100 lb of seed per ac. and replicated 4 times in 10’x60’ plots. Dry conditions in the fall of 2020 and spring of 2021, delayed germination and growth. Fifty pounds of Nitrogen (N) per acre as urea was spread on half the plots on April 6, 2021 and April 5, 2022, as the forage started to break dormancy and just ahead of predicted rainfall. Plots were mechanically harvested with the 3-foot-wide Carter Harvester on May 26, 2021 and May 31, 2022 and tested for nutrient analysis. The two-year average yield and quality data is in Table 1.
Following the spring harvest of the winter annuals, all forage was removed from the plots and four summer annuals were drilled into these same plots on June 9, 2021 and June 21, 2022 at a target rate of 40 lbs/ac. The treatments in 2021 were hybrid brown mid-rib (BMR) pearl millet, Japanese millet, Piper sudangrass and dwarf BMR sorghum sudangrass and the 2022 treatments were ExCeed BMR hybrid pearl millet, Viking BMR brand hybrid 200 and 232 sorghum/sudangrass, and Piper sudangrass, each with either 50 or 100 pounds of nitrogen per acre.
Fifty pounds of nitrogen per acre as urea was applied to all plots on June 11, 2021 and July 8, 2022 and sprayed with 32 oz/ac Roundup Powermax on June 13, 2021 and June 20, 2022 to kill winter annual forage regrowth. In 2021, less than 1.5” of rain fell during the month of June (Table 5). An additional 50 lb/ac of nitrogen as urea was applied July 14, 2021 or July 23, 2022 to half the plots. First cutting was harvested on Aug. 3 in both years.
In 2021, the Japanese millet had a few seed heads showing at harvest but no seed heads were visible on the Pearl millet, sorghum/sudangrass or sudangrass. In 2022, no seed heads were visible at the first harvest in any plot.
Two passes on the north and south sides were cut with a discbine and the center 10-14’ was left unmowed for a comparison to a single harvest system. All mowers were set to leave at least 8-10” residue height. Mowed forage was removed from plots on Aug. 6 both years. The second harvest was cut Sept. 14, 2021 and Sept. 22, 2022, using the Carter harvester on the earlier harvested plot sections. In the uncut sections, 5 feet 3 inches of row (1/10,000th acre) were hand harvested, weighed and sampled. The remaining forage was mowed as low as possible and removed from the plots. In 2022 a leaf blight limited the yield and quality of the Piper hybrid sudangrass but did not affect the other treatments. Disease damage started to appear in late July and continued to worsen throughout the season and the ISU Plant Diagnostic Clinic reported that the blight was caused by the same pathogen that causes Northern Corn Leaf Blight in corn.
The 2-year average summer annual forage yields and quality are in Tables 2, 3 and 4.
Application to the farmThere are several benefits to the winter annual/summer annual forage system including breaking up the traditional corn/soybean rotation, reducing insect, weed and disease cycles, applying manure while the cow grazes and producing 9-12 tons of forage feed on a dry matter basis per acre. Rotational grazing this annual forage system utilizing 50% of the forage produced will result in about 285 cow grazing days per acre. Plus, most of this grazing occurs at timepoints when our perennial cool-season pastures aren’t productive such as early spring months or during the summer slump.
We’ve used this illustration (Figure 2) to demonstrate how a cattlemen can use annual forages to fill the gap in his or her perennial pasture system. Winter cereal rye or triticale can be planted in the fall to provide early spring grazing before pastures are ready. While rye will break dormancy first and provide a big flush of growth early, it also matures early, in comparison to triticale that will start growing a couple weeks later but provide good feed quality a little later in the season. In addition to the feed value, there is a huge benefit to calf health to get spring calving pairs out of the confined calving lots on onto this forage.
Producers can follow the winter annual forage with either a grain crop or a summer annual. The summer annuals are ready to graze in late July or August giving our perennial pastures time to regrow for fall grazing. Depending on the season, you might graze these once or twice and then stockpile for winter or swath grazing, or continue grazing until freeze kills the plants. One word of caution is to beware of the potential for prussic acid poisoning in sorghum/sudangrass or sudangrass in the fresh new shoots following grazing or a frost.
Here is a little cowboy math to help estimate how much of the winter annual/summer annual rotation to seed to support a 50 cow herd assuming a 1400# cow consumes 35# dry matter per day.
10 ac Cereal rye @ 4T dry matter /acre and 70% grazing utilization = 32 grazing days for 50 cows
10 ac Pearl millet @ 5T DM/ac and 60% grazing utilization in 2 rotations = 34 grazing days for 50 cows
One of the big challenges is to convince cattlemen to pull some ground out of crop production for grazing purposes, especially with $6+ corn. But remember, you don’t need a lot of acres to grow a lot of feed. I think everyone has a few small fields that are difficult to plant and harvest or are a hassle to manage along creeks and pastures. Those fields are ideal to rotate into the annual forage system for 12 or 18 months to help support the cow herd. When annual forage fields are adjacent to pastures, it reduces the issues of water access and fencing that exist in some other fields.
We would like to thank the support of our funders and partners including the Iowa Beef Center, the North Central Extension Risk Management Education Center supported by USDA/NIFA under Award Number 2018-70027-28586, Ken Pecinovsky at Northeast Research and Demonstration Farm, and Welter Seed & Honey, Melbourne Seed, and Albert Lea Seed.
References available upon request
Schwab and Lundy-Woolfolk are Extension beef field specialists, both with Iowa State University Extension and Outreach.
