Factors to Consider Before Interseeding Soybeans into Wheat This Spring

Modified Relay Intercropping (MRI) is the planting of soybeans into standing wheat whereas double crop soybeans are planted after wheat is harvested. Vyn et al, found that relay intercropping of soybeans yielded better than double cropping of soybeans north of I - 70 in Indiana (http://www.agry.purdue.edu/staffbio/AY316.pdf).  In 15 years of replicated trials in North Central Ohio on the MRI system, yields have averaged 76 bu/acre for wheat and 30 bu/acre for soybeans (70 bu/wheat and 54 bushel soybeans in 2013). Wheat yields in favorable growing seasons have exceeded 90 bushels per acre and while soybeans have yielded over 60 bushels per acre in small plot replicated trials.

However, to successfully MRI soybeans into wheat, wheat row spacing modification to allow soybean planting equipment to pass without running down wheat plants..  Wheat Row spacing for MRI has ranged from 10 to 20 inches. As wheat row spacing widens, wheat yields may decline http://corn.osu.edu/newsletters/2011/2011-27/wheat-variety-yield-in-15-inch-rows .

There have been various row configurations used to allow soybean planting equipment.  For example, some wheat producers will use a twin row planter or slide row units together to a 6 inch wheat row spacing and leave a 14 inch planting strip for soybeans.  Some producers may wish to utilize corn or soybean planter to sow wheat and this normally is a 15 inch row configuration.  For 2013 data on 15 inch row wheat go to:  http://oardc.osu.edu/wheattrials/default.asp?year=2013  Row spacing data would suggest that wheat is an adaptable plant that will yield well over various row spacing’s up to 15 inches.

To accommodate soybean planting into wheat and allow for better wheat management via fertilizer, herbicide and/or fungicide applications, a tram line is essential. Generally, the tram line will be set up for the  MRI  tractor tires. Planter equipment tires are moved if necessary to follow tractor tires.

In summary, for the best interseeding results, set up your equipment in the fall and practice MRI prior to the actual planting of wheat.  To attempt to interseed wheat  in the spring without having set up the equipment to drive through the wheat may cause significant damage and reduce wheat yield. The act of  interseeding may also reduce wheat yield.  Interseeded wheat yields were reduced about 3 bushels per acre compared to non-interseeded wheat in 3 years of replicated trials in north central Ohio.

For an overview of some of the 2013 MRI plot results go to: http://croppp.cfaes.ohio-state.edu/ 

About the C.O.R.N. Newsletter

C.O.R.N. Newsletter is a summary of crop observations, related information, and appropriate recommendations for Ohio crop producers and industry. C.O.R.N. Newsletter is produced by the Ohio State University Extension Agronomy Team, state specialists at The Ohio State University and the Ohio Agricultural Research and Development Center (OARDC). C.O.R.N. Newsletter questions are directed to Extension and OARDC state specialists and associates at Ohio State.