Rotational Effects of Cuphea on Corn, Spring Wheat, and Soybean

Authors: Gesch, Russell - Russ; Archer, David; Forcella, Frank

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/5/2009
Publication Date: 1/1/2010
Citation: Gesch, R.W., Archer, D.W., Forcella, F. 2010. Rotational Effects of Cuphea on Corn, Spring Wheat, and Soybean. Agronomy Journal. 102(1):145-153.

Interpretive Summary: Most farmers in the northern Corn Belt grow just corn and soybean and a little bit of wheat. Sometimes they rotate these crops every other year, but sometimes they grow one crop, such as corn, year after year in the same field. This has resulted in certain insect, disease, and weed pests becoming well adapted to surviving in fields where only a couple of crops are rotated, or one crop is grown year after year. In turn, the farmer must use a great deal of pesticides and fertilizer to maintain high crop yields. One way to reduce this problem is to add more types of crops to a crop rotation. Cuphea is a new oilseed crop that we are developing for commercial production in the northern Corn Belt, but we don’t know how it might affect corn, soybean, and wheat when it is added to rotation with these crops. Therefore, we conducted a 4-year long field experiment in Morris, Minnesota, to test the effects of cuphea when rotated one year to the next with these crops. We found that seed yields of corn, soybean, and wheat were not negatively affected when they were grown the next year after cuphea. Also, these crops did not negatively or positively affect cuphea yields when they were grown the year before. Cuphea production the previous year did, however, result in better wheat plant stand establishment the next year. Furthermore, the wheat grain harvested had an 8% higher protein content when it was grown after cuphea than when it was grown after corn or soybean. The cost of growing cuphea was higher than that for growing soybean and wheat, but it was less than that for growing corn. We found that for cuphea to be profitable for a farmer, he or she would need to get paid about $1830 per ton of harvested seed. We also found that corn and soybean were more profitable when they were grown the next year after cuphea than when they were each grown year after year. Our results prove that cuphea can be successfully rotated with corn, soybean, or wheat. We recommend that it be rotated the year after growing soybean and the year before growing corn or wheat. Besides other crop scientists, our finding will be beneficial for seed companies contracting with farmers to grow cuphea, and for university extension and crop consultants helping farmers to manage cuphea production in their fields.

Technical Abstract: Agricultural diversity is lacking in the northern Corn Belt. Adding crop diversity to rotations can give economic and environmental benefits. Cuphea (Cuphea viscosissima Jacq. x C. lanceolata W.T. Aiton; PSR23), which grows well in the northern Corn Belt, is a new oilseed crop and a source of medium-chain fatty acid oils. However, little is known about its rotational effect on corn (Zea mays L.), soybean [Glycine max (L.) Merr.], and spring wheat (Triticum aestivum L.), which are predominant crops in this region. A study was conducted from 2004 to 2007 in west central Minnesota to evaluate the effects of all two-yr rotational sequences of cuphea with corn, soybean, and wheat on crop yields and stands, soil water and N content, and production economics. Cuphea seed yield was not affected by previous crop, nor were yields of corn, soybean, and wheat affected by cuphea. Wheat stand was 17% greater and grain crude protein content 8% greater when following cuphea than when following corn or soybean. Wheat’s positive response was primarily due to a high rate of residual nitrate-N remaining after cuphea harvest. Cuphea had a slight negative influence on soybean stands, but this was not reflected in yield. Production cost of cuphea averaged $172 ha-1 less than corn and $118 and $126 ha-1 higher than soybean and wheat, respectively. While cuphea was not profitable at a price less than $1830 Mg-1, it could serve as a useful rotation crop, with higher net returns for corn and soybean grown following cuphea than when growing these crops in monoculture. When corn and soybean followed cuphea, average net returns were $274 and $95 ha-1, respectively, greater than monocultured corn and soybean. Cuphea fits well in rotation with corn, soybean, or wheat, but may be best after soybean and before wheat or corn.