By Steve Prochaska
Modified Relay Intercropping (MRI) is the planting of soybeans into headed wheat that may occur up to 6 weeks prior to wheat harvest. MRI is system where two crops, wheat and soybeans can be harvested in the same growing season.
1. To determine equipment suitability for modified relay intercropping; begin in fall by runningwheat drill/planter set to appropriate row spacing in fallow ground and then ‘soybean seeder’ to evaluate where tractor tires, planting equipment tires and openers will fit in wheat rows. Plan for atram line and also make wheat row spreaders for tractor tires and planting equipment to move wheat out of row when planting.
2. Wheat Row spacing may range from 10 to 20 inches Wheat rows beyond greater than 10 inches may experience a small yield drop. The drop in yield is relatively small up to 15 inches (from 5 to 7%)over various studies.
3. Plant seed to achieve 1.6 to 2.2 million seeds/acre or if in 15 inch rows not more than 25 seeds per foot of row.
4. Attempt to sow wheat by Oct. 5 in North Central Ohio for best results ( ie must use appropriate soybean variety that will come off to permit timely wheat harvest). There is not any merit to planting prior to Hessian Fly free Data ( for example: Sept. 26 in Crawford County).
5. Select wheat varieties that are: High yielding; disease resistant; early maturing and short if possible. Be sure seed is treated with appropriate fungicides. Go to http://agcrops/osu.edu and check wheat variety performance trials and 15 inch row trial.
6. Incorporate a tram line for sprayer and tractor tires as this will greatly aid in management and precision soybean interseeding.
7. Apply fertilize appropriate for wheat production and 30 bu/soybeans (our approximate long term average).
8. Control marestail and other weeds prior to planting wheat either with appropriate tillage (not vertical tillage) or glyphosate + Sharpen.
8. Grow the best wheat you can grow ( ie: an appropriate spring nitrogen rate applied, disease control as needed as needed and 2,4-D applied on wheat in the spring prior to wheat jointing or at Feekes GS 6.)
9. Interseed soybeans about 30 to 40 days prior to wheat harvest at 225,000 + seeds/acre ( ie if wheat harvest is expected June 25, may start interseeding around May 25). The fall wheat planting date, variety, weather and wheat row spacing selected will influence the interseeding date. May use up to 3.5 maturity soybean in North Central Ohio ( later maturity soybeans may allow later pods to develop with late season rains). Wheat will often be in flower when interseeding. This will not harm wheat as long as it is not run down. MRI system works because wheat is flexible, tough adaptable plant. The larger the soybeans are at wheat harvest; the more susceptible to combine wheel damage. Can lose significant soybean stand – larger the header; less soybean stand loss.
10. Harvest wheat early as can be threshed, if possible at 20% moisture and dry.
11. Cut wheat at top of soybeans.
12. Aggressively chop and evenly spread wheat wheat residue.
13. Control weeds; remember marestail must be controlled in the wheat.
14. Scout for defoliators/pod feeders in late July and early August– may damage interseeded or double crops beans heavily.
Source : osu.edu