July Drought and Soybean Prospects

By CnAgri2012-07-20 19:46:02 Print

With no relief from the ongoing drought in sight, crop ratings continue to drop. University of Illinois crop sciences professor Emerson Nafziger said that only 11 and 17 percent of Illinois corn and soybean crops, respectively, were rated as good or excellent this week.

Corn crop prospects continue to worsen with loss of leaf area and poor or failed pollination in dry areas. As leaf color and area continue to decline, so does yield potential.

"While we remain more optimistic about soybean prospects than about corn, soybean yield potential is beginning to decline as more time passes without enough water to keep plants functioning well," Nafziger said.

Soybean plants in dry areas are short, and the size of leaves and petioles has been reduced due to the ongoing lack of available water to expand cells. The result has been plants with a narrow canopy.

In wider rows, plants are unable to join canopies across the rows, which reduces their ability to intercept sunlight and lowers their yield potential.

A more pressing problem is the lack of pod formation, at least in early-planted fields.

As stress continues, racemes above these lower nodes may continue to dry up and pods either will not form or will drop off.

The yield potential of stressed soybean plants depends on their ability to respond to rainfall by producing more nodes at the top of the plant and then by flowering and setting pods on these nodes.