The conventional wisdom around drought-stricken Indiana last week was that except in a few, oasis areas, corn was in big trouble. Bob Nielsen, Purdue University Extension corn specialist, confirmed that in areas of drought stress and with extreme heat, if corn was in pollination losses in yield potential could run 10% per day or higher. It doesn't take a rocket scientist to figure out what the weather did to corn yields in a good share of Indiana last week.
However, conventional farmer wisdom also held that soybeans could hold on for water. The critical period for soybeans is typically not until August. If soybeans get rain in August and make a good crop.
It's conventional wisdom because that's how it's played out before, especially in the 1988 and 1991 drought. However, Shaun Casteel and Tony Vyn, Purdue University Extension agronomists, say it's a different ballgame this year.
"The critical period for soybeans in 2012 is right now through the next three weeks," Casteel says. "The beans have been holding on, doing more rooting than growing. The lack of growth has already cost yield because the plants will have fewer nodes. Also, even if this drought broke today, the lower pods that have already formed won't finish normally. Damage is already done.
But that's not the big kicker. "They can't wait forever," Casteel says. "Since this crop was planted so early, it is much farther along than a typical crop." Yes, soybeans are partially controlled by day length, he notes, but they are also influenced to some degree by heat units. Early planting and excessive heat has moved the crop along.
"They need rain within the next three weeks. This year this is the critical period for most soybeans in Indiana. Bacterial nodules are starting to wither in some places. It's just a whole different situation this year and they are going to need the rain before August if we are going to see decent yields."