Are you a bit greedy, and are you thinking about planting double crop soybeans into your wheat? Certainly, two high value crops in one year will help pay the cash rent, but make sure you take care of both crops, or you may create significant problems and not have any crop. Oooops!

First, the risks. You will have a significant chance at increasing the disease pressure for both crops. You are also negating the weed, disease, and insect control opportunities received from a typical crop rotation. Those are the primary warnings of Ohio State University agronomist Jim Beuerlein, who offers a roadmap toward doublecropping.

Beuerlein also warns there are two requirements for a profitable double crop:
1) Adequate time for the second crop to mature.
2) Adequate water for the second crop to mature.

Time and water, water and time. That is the bottom line to profitability. But Beuerlein also notes that because soybean maturity is determined by the length of the day, it is particularly suited for a second crop since it will begin growing when the days are the longest. But the water factor at that point is also important, and Beuerlein says the top three inches of soil cannot be dry when beans are planted into wheat. That will slow down the germination and retard any root growth that starts. He says the best soil for double cropping are ones with good water holding capacity and are considered “good corn soils.”

Your wheat crop needs to be harvested as early as possible. If you have planted a full season wheat, don’t go to the expense of buying soybean seed. If you are going to be successful in doublecropping, your wheat crop should be an early to mid-season wheat variety, and what is more, you are going to harvest it early. Beuerlein suggests cutting the wheat when moisture starts to dip below 20%, in order to get it off the field and let the sun hit the soybeans. That means you will probably have drying costs associated with the wheat. By letting it field dry below 14% moisture, you have saved drying money but you have also lost a couple weeks that the soybeans need.

Watch the June temperature, which will be integral for rapid maturity and dry down of the wheat. If that is not happening, reconsider your double crop plans. In addition to the short season wheat, you also need a short season soybean variety. That will improve your chances of the beans maturing before the first frost next fall. Beurlein says,” Ohio studies have shown that early planting and July-August rainfall have a much greater impact on double crop soybean yield than does variety.”

Your wheat straw must be managed to avoid problems for the soybeans. They need to get up and out, and if you can clip the straw and bale it, that provides additional income. If you are not baling the straw, chop it and spread it so that a no-till drill can plant through it. At that time, soil moisture is imperative. Beuerlein says July and August rain usually will not replace what the second crop is capturing, and the double crop beans need a head start provided by the moist soil at planting. He says, “An important rule of thumb to consider is: “If June is dry, don’t try to double crop.” Increased nitrogen application for the small grain produces more vegetation, which increases soil moisture use. Because wheat uses moisture from the upper 8 to 12 inches of soil, growers should be aware of the moisture remaining below that depth.”

The Ohio State agronomist is highly recommending that the double crop beans be planted with a no-till drill, and ideally planted the same day the wheat is harvested. He recommends a narrow row of 7.5 inches, with a planting rate at least 250,000 per acre to obtain sufficient leaf canopy and yield. He recommends that rate because the beans will be short and will need to create a canopy as soon as possible.

Weed control is necessary, but Beuerline says it is not difficult. Weeds surviving the wheat harvest should be knocked down with glyphosate or grammoxone. The use of Roundup Ready beans may already be in your plan to control post-emergent issues. Earlier, when the wheat reaches the hard dough stage Beuerlein says a 2,4-D amine application can be used to control some weeds that might be a problem for the soybeans that follow the wheat.

Summary:
Double crop soybeans will provide added cash flow, but will require sufficient time to grow and sufficient water to grow. An early departure of the wheat, helped by an early maturity and an early harvest, will allow soybeans to be planted the same day. However, there must be sufficient moisture, and if the time is still in June, there would be time available for soybean growth and maturity before the onset of frost. The beans should be drilled in narrow rows with a high population to achieve a canopy as early as possible.