Ames, Iowa-Iowa State researchers, looking to the day when fossil fuels needed for fertilizer and operating farms won’t be so cheap, have found that changing crop rotation can make a big difference in both areas without sacrificing yields or profits. “I think many farmers recognize that what we do now derives in a large part from relatively inexpensive energy,” said Agronomy Professor Matt Liebman. “And if that system changes, then we may have to re-evaluate what’s the best system for our land and our climate.” Liebman and his colleagues compared a conventionally managed two-year corn/soybean rotation system with two systems that they refer to as low external input: a three-year corn/soybean/small grain plus red clover system, and a four-year system of corn/soybean/small grain plus alfalfa. Synthetic nitrogen use was 59 percent lower in the three-year and 74 percent lower in the four-year system than in the two-year system. Herbicide use was reduced 76 and 82 percent, respectively. Corn and soybean yields were as high or higher, and weed biomass in corn and soybean was low. Orvin Bontrager, a veteran farming adviser with Servi-Tech Inc.’s crop and environmental consultants, cautioned in a published report on the research that although there is a savings on the energy, there might not be enough labor to handle the additional crops if most farms switched to the new system. He conceded that “if the price of oil does get that high, fertilizer and chemicals obviously get a lot higher. And if the prices of crops do not follow along, then obviously we will be going to something like this because it just makes economic sense to do that.”
Transparency Across the Fertilizer Value-Chain