Soybeans (Glycine max) are a common annual farm crop produced for the oil market, as well as livestock feed and human consumption. The warm-weather legume grows under a variety of climate conditions, and many new hybrids offer shorter maturity dates, allowing northern farmers more options for growing soybeans. Soybeans should not be planted until the soil temperature is at least 60 degrees Fahrenheit and prefer average daytime temperatures in the 70s.
Maturity Dates and Varieties
Different varieties of soybeans mature at different rates. This is often stated in seed packets as a number of days and reflects the estimated time between planting and crop maturity. Many soybean varieties have maturity dates ranging between 90 and 150 days, with some hybrids developed for northern regions maturing even faster. Select a variety suited for your local climate and its number of anticipated growing days.
Soybeans respond to the shortening days in the fall by accelerating the seed-maturing process. This means delayed planting may still lead to a harvestable crop in the fall. Purdue University estimates that for each three days spring planting is delayed, harvest is delayed one day. The acceleration of the maturity may lead to a smaller yield because the plant may set fewer pods.
It commonly takes a soybean seed about two days to germinate and sprout. The new plant doesn't emerge from the ground until about one week after planting. Plants are at the most vulnerable during this process and can be damaged by low temperatures or pests. If the initial planting is lost, the crop can sometimes be replanted with a shorter-maturing variety.
The best time to harvest soybeans is when the seeds are fully developed but the pod has not yet turned from green to yellow. Most commercial varieties of soybeans hold in this window of development for about a week before the pod starts to dry. Once the pod dries, it is likely to shatter during harvest, leading to seed loss. Harvest dates are determined by the crop conditions, since the maturity rate is affected by temperature and humidity levels. For example, a 100-day soybean may take 110 days from planting to maturity if conditions are cooler and wetter than normal.
Keith Allen, a 1979 graduate of Valley City State College, has worked at a variety of jobs including computer operator, medical clinic manager, radio talk show host and potato sorter. For over five years he has worked as a newspaper reporter and historic researcher. His works have appeared in regional newspapers in North Dakota and in "North Dakota Horizons" and "Cowboys and Indians" magazines.