Some Arkansas soybean farmers are trying to minimize the impact of a possible drought this summer by planting very-early maturing and ultra-early maturing varieties in late March and early April. This could be risky, warns Lanny Ashlock, soybean agronomist for the Cooperative Extension Service, University of Arkansas.
He said the university has limited information on the performance of these maturity groups especially when planted so early. He said farmers are planting varieties from groups 2, 3 and 4.
“We're almost pushing the envelope too far,” he said. “I don't think planting maturity Group 2s in late March is the way to go. We definitely need more research before recommending this practice.”
He said Group 2s and Group 3s, especially early Group 3s, planted in late March and early April can have trouble attaining adequate plant height, growth may not be uniform and there may be a grain shatter problem at harvest. He said many of the lower pods may be so low on the plant that they could be difficult to harvest.
“Group 2s and 3s tend to be short, especially when planted in cooler soils associated with very early planting dates. These cooler soils often result in a delayed and prolonged germination period. Also, the day length is not conducive for optimum growth and development.”
He said he could understand farmers' concerns. “We've had three consecutive years of drought in Arkansas for soybean production. 2000 was the third-worst production year for soybeans in the last 50 years. Growers are looking at ways to minimize the effects of heat and drought. One way is to plant very-early to ultra-early maturing varieties and try to make this crop mature before the typical dry period, from late July through early September, sets in.”
However, he considers Group 2s as experimental at this time.
‘We're almost pushing the envelope too far. I don't think planting Group 2 soybeans in late March is the way to go. We need more research before recommending this.’
“I'm not recommending 2s to any Arkansas farmer right now. They're strictly in the research stage. I'm not sure what they offer that a good late Group 3 doesn't.”
Ashlock said early-maturing varieties were developed to get around the problem of late summer droughts.
“For years, Arkansas' major limitation in soybean production has been moisture in the reproductive stage. Traditionally, we've planted maturity Group 5s, which enter the reproductive stage in August and through September. Those tend to be very dry months for us.
“In the late 1980s, we started looking at planting early-maturing varieties earlier so that they go reproductive in July and early August. Primarily, we've gone with Group 4s planted in early April.”
Recent research, Ashlock said, suggests that late 3s or early 4s can perform well in Arkansas when planted in mid-April and early May.
He said if Arkansas gets June rains and one or two July rains, this system works well. “In the years when we have a dry June, this system has problems and doesn't look as good. Last year, we had a wet June and we grew an awesome plant, but we got no rainfall in July, so we had BB-sized grain. We simply didn't have enough moisture to fill out the seed. One irrigation or timely rain would have doubled our yields in some instances.”
Ashlock said farmers should plant a significant acreage of early-variety beans for dryland production. They should plant mid- to late-Group 4s in early April, especially in south Arkansas, and then incorporate the early 4s and 3s in the last two weeks of April.
With irrigation and proper variety selection, farmers can obtain satisfactory yields from planting some of the very early-maturing varieties well into May, especially in north Arkansas.
Lamar James is an Extension communications specialist with the University of Arkansas.