Dual seeding system satisfies moral conundrum

In the food vs. fuel debate, there may finally be a comprise.

If a field can grow a biofuel crop and a human food crop in the same year, many moral questions surrounding the issue of using cropland for bio-fuel production can be answered.

Russell Gesch of the United States department of agriculture’s Soil Conservation Research Farm in Morris, Minnesota, says a two-crop system is doable.

He says the secret is identifying a crop that has a short enough growing season so the farmer can still grow the other crop. It doesn’t matter if the short season crop is the first or second one.

Farmers realize that neither crop will hit high yield targets, but the sum of two can create higher total revenue.

For example, one acre of Minnesota farmland can grow 1,300 pounds of winter camelina.

In that same growing season, that same one acre can also grow 40 bushels of soybeans.

Winter camelina, a member of the mustard family, is becoming sought after as a biofuel commodity and a specialty food. The price for camelina closely follows canola, and is higher than canola when sold to the food market.

At Morris, Gesch seeded winter camelina at the end of September.

“We’re using two different dual cropping methods. Sequential double cropping is simply a matter of harvesting the first crop earlier than normal and then quickly planting your second crop, which ends up being later than normal.

“In this case, the camelina is harvested in late June or even early July. The soybeans go into the ground immediately. Of course, this doesn’t give the soybeans much of a chance for a decent yield.

“The other system is called relay-cropping. We plan it so the two growing seasons overlap. The soybeans are planted in late April or early May, just before the camelina starts to bolt. The soybeans go between the rows of camelina.”

Gesch says the winter camelina survived very well, likely helped by the snow-catch. The scheme makes good use of moisture. There is generally an abundance of moisture in the spring after the snow melts. This water is usually close to the surface, which is ideal for a shallow-rooted plant like camelina.

Gesch says once the camelina bolts, it starts to flower and set seed quickly. Also, it matures very quickly, making it an excellent candidate for any dual seeding plan.

“We’re harvesting our camelina mid- to late-June. The soybeans are out of the ground, but they’re not very big yet. We come along with the combine straight-cut header just above the tops of the soybean plants. We’ve seen very little damage to the soybeans.”

He says there probably is a trade off. If the operator wants to make sure he gets every last camelina pod, there may be some damage to the tops of soybean plants. Conversely, if the operator sets the height to ensure no soybean plants are damaged, then a few camelina pods will go unharvested.

“The soybean yield doesn’t come out of this too badly. Compared to a normal mono-crop system in this area, we’re able to get 80 to 85 percent compared to a typical full season yield.

“You’re not going to get two crops off one field in a single season and expect to get a 100 percent yield from either of them. You have to look at factors such as winter erosion protection, snow catch giving you better moisture and nutrient recycling.

“You’re hanging on to that nitrogen and phosphorus instead of allowing it to leach out to groundwater and surface water. You’re spreading out the workload and now you have two different crops to sell.”

For more information, contact Russell Gesch at russ.gesch@ars.usda.gov.

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