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December 20, 2002

Soybeans find no 'fair-weather' friend during Purdue trials

WEST LAFAYETTE, Ind. – Heavy spring rains got soybean planting in Indiana off to a later-than-usual start this past season. Subsequent drought conditions exacerbated crop stress.

The same troublesome weather that tested Hoosier farmers' patience also threw a wet blanket on Purdue University's annual soybean performance trials.

Like most Indiana producers, Purdue research agronomists missed the optimum soybean planting period by three weeks or more. The late planting, followed by dry, hot conditions, resulted in yields lower than the three-year trial average.

"We got shot out of the saddle," said Kelly Day, senior research agronomist and Purdue's soybean performance trial supervisor since 1969. "The first half of May is the optimum planting time for soybeans in Indiana, but only 4 percent of the crop was planted during that period.

"When we finally got soybeans planted, the rain stopped and hot weather arrived. We were fortunate to have beneficial soil moisture reserves from spring rains. During June, Porter County trials received less than an inch of rain and in July, Knox County trials received 1 inch of rain."

Purdue's soybean trials measure the performance of about 150 public and private lines, in both conventional and Roundup Ready soybeans. Results appear in Purdue University Station Bulletin B 819, "Performance of Public and Private Soybeans in Indiana, 2002."

The publication is available at county offices of Purdue Extension or may be downloaded online.

"The intent of these trials is to increase the knowledge of the farming community so that producers can make more informed decisions about soybean seed," Day said.

Soybean trials were conducted at Purdue agricultural research centers in Porter, Tippecanoe, Randolph, Knox and Jennings counties. In Jennings County, soybeans were planted in both conventional and no-till seedbeds.

Generally, 2002 trial yields were down from those in 2001, but mostly higher than the state's 2002 soybean average yield of 41 bushels per acre.

Yield averages for conventional soybeans in maturity group II ranged from 38.7 bushels per acre in Porter County to 58.5 bushels per acre in Tippecanoe County.

The three-year yield average for conventional soybeans in maturity group III ranged from 53.9 bushels per acre in Knox County to 61.1 bushels per acre in Randolph County.

Roundup Ready soybeans, which make up the vast majority of soybean acres in Indiana, posted slightly higher yields than conventional varieties. Yield averages for maturity group III in conventional tillage ranged from 45.6 bushels per acre in Porter County to 70.7 bushels per acre in Tippecanoe County.

The two-year yield averages for Roundup Ready soybeans in maturity group III ranged from 64.5 bushels per acre in Porter County to 67.8 bushels per acre in Tippecanoe County.

Soybean trial entries also were measured for lodging and plant height. Few entries exhibited lodging problems, but many plants were a few inches to several inches shorter than the three-year average.

Despite planting delays, brutal summer heat and on-and-off precipitation, soybeans performed better than expected, Day said.

"Even though planting was three to four weeks late, harvest got under way the last of September and was wrapped up statewide by mid-November," he said. "Overall, the grain quality was good.

"Without the beneficial soil moisture recharge during the spring, the drought impact would probably have been more severe. We went into planting with moisture supplies that were favorable. I'll take a wet spring over a wet fall any time. A wet spring is going to get better, but a wet fall is only going to get worse."

Fourteen seed companies and a public certified seed producer submitted entries for the 2002 trials. To address statistically significant performance differences, Purdue research agronomists computed an analysis of variance and a test of significance. The procedure is explained at length in the soybean performance bulletin.

Writer: Steve Leer, (765) 494-8415, sleer@purdue.edu

Source: Kelly Day, (765) 583-1406, kday@purdue.edu

Ag Communications: (765) 494-2722; Beth Forbes, bforbes@aes.purdue.edu; http://www.agriculture.purdue.edu/AgComm/public/agnews/

Related Web sites:
Purdue Variety Trials page
Purdue Department of Agronomy


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