KAUKAUNA - With harvested winter wheat fields being a prime candidate for the establishment of late season cover crops in Wisconsin, a question that has arisen is how well different cover crop species will fare when forced to compete with the volunteer wheat that appears in many of those fields.
Answers to that question are being sought in a plot at Van Wychen Farms in Outagamie County that is being overseen by Aaron Barclay of rural Seymour. He is with Forage Innovations, a seed dealership owned by Dan Olson of Lena in Oconto County. The dealership is the second largest for Byron Seeds but it also obtains seeds from other suppliers.
The test plot which was seeded on August 25 is located on somewhat poorly drained soil next to the farmstead buildings. Part of the plot was formerly covered by a building and a portion of it receives runoff water from around a freestall dairy barn.
Having research plots for field crops is nothing new for Van Wychen Farms, which has cooperated with the University of Wisconsin Extension Service on many projects in the past and is also a charter member of the Lower Fox River Farm Demo Network that is based in Outagamie and Brown counties.
Field day presentation
During a field day sponsored by the network, Barclay guided the attendees through the plot where volunteer wheat was a competitor in many of the test strips. He observed that the ideal situation would be to have very little harvesting loss of the wheat that turns into volunteer growth but added that having it for ground cover and organic matter is not a negative.
Among species in the plot are winter and spring triticale, cereal rye, and annual ryegrass, all of which Barclay touted for their large root masses as a way to improve soil health and biological activity. While the growth of cereal rye in some parts of the plot was lagging, perhaps inhibited by an allelopathic carryover from the wheat, he stated that cereal rye is often the best cover crop choice in difficult growing situations and is a good trapper of nitrogen.
Barclay was impressed by the vigorous growth of the hairy vetch in the plot. He said it is a good source of nitrogen for a followup corn crop, indicated it should survive the winter, and then would be a good candidate for a roll down of its foliage bio-mass before a no-till planting of corn.
Other species in the plot included oats, spring barley, spring and summer pea varieties, sunn hemp, tillage radish, crimson clover and Berseem clover. While the Berseem clover stand looked great in the plot, Barclay noted that the crimson usually grows faster and is a good builder of nitrogen.
Winter survival concerns
Although many of the cover crops will die during the winter, that is not a guarantee, Barclay warned. He recalled how even some oats in cover crop stands survived the winter of 2015-16.
Growers of cover crops need to be aware that a herbicide treatment with Round-Up in the spring will not kill canola, rapeseed or any radish that survived the winter, Barclay pointed out. He explained that a different herbicide or a physical takeout of the crop would be needed.
Crop species functions
Barclay outlined three functional categories for cover crop species. They are nutrient creators, nutrient mobilizers and nutrient stabilizers.
The creators, which are the legumes, including the hairy vetch, have their value in creating nitrogen and a few other nutrients. Mobilizers, which are the radishes and brassica species, extract nutrients from the soil and make them available to following crops. They also decompose quickly.
Nutrient stabilizers are high carbon plants which decompose slowly, Barclay pointed out. They consist of small grains and grass species which draw up unstable nutrients that might otherwise leach from the soil.
Barclay can be reached by email firstname.lastname@example.org or by phone to 920-606-1460.