Iowa State University researchers say an earlier planting date for soybeans in the spring takes better advantage of nitrogen left behind from corn production. ISU agronomy professor Michael Castellano says it would help reduce nitrous oxide emissions.
Crop rotation – the practice of planting corn in a field one year and soybeans the following year — already reduces emissions by 50 percent. Castellano says most research has focused on reducing the amount of nitrogen applied to help corn grow, which also reduces farm chemical costs. Castellano says this new research finds that once nitrogen for corn production is reduced to the optimum level, the main way to cut nitrous oxide emissions is to move up the planting date of soybeans.
Nitrous oxide is the primary source of greenhouse gas emissions from crop production. Nitrous oxide is the byproduct of microbial activity in soil that is essential for growing grain. Castellano says farmers tend to focus on getting corn in the ground early because it’s a more expensive crop to grow, but moving up the soybean planting date is likely to result in higher soybean yields because the plants have a longer growing season.
Castellano and another I-S-U researcher worked on this project, which dramatically increased the amount of time plants are growing on farmland. Cover crops were planted after the beans were harvested.
The study was published in the November issue of a scientific journal called “Nature Sustainability.”
