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Delayed planting may be blessing in disguise for soybeans

Rain has caused planting delays in the Midwest states for many growers. But these delays may be more beneficial than detrimental for soybeans says a Purdue University expert.


May 23, 2008
By Purdue University

May 16, 2008

West Lafayette, Ind. – Even though planting soybeans earlier has been an
increasing trend for growers, a
Purdue University expert said this year's delayed
planting may be more beneficial than detrimental.

The
abundance of rain that has washed over the
Midwest has caused planting delays in many
states.
Indiana and Ohio have 19 percent and 21 percent,
respectively, of the intended soybean crop planted, according to the latest
report from U.S. Department of Agriculture's National Agriculture Statistics
Service. Combined, this means that nearly 7 million acres are not yet planted.

"But
this late planting may be a blessing in disguise," said Ellsworth
Christmas, Purdue Extension soybean specialist. "Soybean seed quality is
horrendous.

"Don't
get me wrong, there is some good quality seed, but an awful lot of it is just
marginal. And that poor quality seed is at much greater risk to rot and
disease, especially if it has to sit in the ground for several days."

Purdue
research shows that growers should plant soybeans between April 25 and May 10
to obtain the highest yield potential.

"We
found that planting after May 10 leads to a 0.5 percent yield reduction per
day," said Andrew Robinson, an agronomy student who examined the
relationship between planting dates and yield. "And, planting after early
June results in a yield reduction of 1 percent to 1.5 percent per day."

Robinson
and Christmas agree that if this is the case, with new crop soybeans at $12 a
bushel and an average yield of 50 bushels per acre, a 0.5 percent yield
reduction per day is a loss of .25 bushels per acre per day or $3 per acre per
day. For a 1,000-acre soybean farm, that's a loss of $3,000 every day soybeans
aren't in the ground.

However,
as long as growers are prepared to plant as soon as the ground is ready, that
may not hold true with this year's weather situation, Christmas said.

Robinson's
research showed that planting in late May or early June resulted in a 10
percent to 15 percent total decrease in yield.

"This
could be attributed to having a shorter growing season, and the length of day
probably played an important role at inducing flowering earlier and causing the
plant to develop quicker," Robinson said.

Robinson's
two-year study confirms what farmers already suspected – planting soybeans
earlier, but not too early, produces better yields.

Robinson
planted soybeans in 2006 and 2007 on six different planting dates, starting at
the end of March and planting one acre every two weeks through the first week
of June. Three varieties were planted each time: an earlier maturing variety,
an average maturing variety and a late maturing variety.

Robinson
not only looked at the relationship between yield and planting date, but also
at how protein and oil content changed with the planting date. Researchers
observed that at earlier planting dates, oil content was higher than at later
planting dates and that protein content was opposite
.