Factors To Consider For Modified Relay Intercrop Soybeans

Modified Relay Intercropping (MRI) is the planting of soybeans into standing wheat. Wheat is a flexible, adaptable plant with a growing season that starts with planting in the fall and ends with harvest in the early summer.  This adaptability allows farmers to capture some 66% of the traditional growing season in Ohio — May 25 to September 30 — to produce a second crop through the inter-planting of soybeans into wheat in late May or early June.

Long-term research at The Ohio State University's Ohio Agricultural Research and Development Center (OARDC) in Crawford County, Ohio and other locations in Indiana has shown that MRI or Relay intercropped wheat can yield at least 90 percent of conventional wheat.

Because of the high probability of growing wheat in an MRI system at 90% or better of conventional wheat, farmers may hedge their crop production and market risk in an MRI system through the opportunity (option) to grow and harvest a crop of soybeans.  Soybean production in an MRI system is more speculative than wheat production due to the need for adequate rainfall in July and August.  Last year’s very dry weather represented the perils of interseeding, in that soybeans were not harvested in the 2012 trial.

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 14 years of replicated trials in North Central Ohio on the MRI system, yields have averaged 76 bu/acre for wheat and 28 bu/acre for soybeans (86 bu/wheat and 0 bushel soybeans in 2012). Wheat yields in favorable growing seasons have exceeded 90 bushels per acre  while soybeans have yielded well over 45 bushels per acre.

To successfully MRI soybeans into wheat, wheat row spacing modification to allow soybean planting equipment to pass without running down plants should be made in the fall.  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 slide row units together to a 6 inch row spacing and leave a 14 inch planting strip for soybeans. Many producers wish to utilize the corn or soybean planter to sow wheat and this normally is a 15 inch row configuration.  For 2012 data on 15 inch row wheat go to   http://corn.osu.edu/newsletters/2012/2012-26/#5.  Row spacing data would suggest that wheat is an adaptable plant that will yield well over various row spacings up to 15 inches.

To accommodate soybean planting 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. If necessary, planter equipment tires are moved to follow tractor tires.

Finally, wheat culture for MRI, outside of row spacing modification, should remain the same as for monoculture wheat.

Source : osu.edu