Source: Purdue University

Indiana farmers have experienced heavy rains this month which has kept them from planting corn, and the weather is calling for even more rain in the next few weeks. However, that doesn't mean that yields at harvest time will suffer at this point.

Precipitation is forecasted to be above normal through the first week of May, following a pattern of heavy rain that has swelled rivers and streams and flooded many fields.

"The rain over the next couple of weeks shouldn't be as heavy as it has been, but the frequency of rewetting of topsoils is the problem," said associate state climatologist Ken Scheeringa, based at Purdue University.

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Farmers had planted only 1% of the corn crop in Indiana as of the week ending April 21, compared to the five-year average of 16% by the same time, according to the USDA's National Agricultural Statistics Service report. Last year at this time, farmers had 43% of the corn crop in the ground at this time, when conditions were unusually dry.

Most fieldwork was halted last week due to the cold temperatures that dropped to 21 degrees and nearly 7 inches of rain. And while temperatures are now finally warming, a trend that typically would help to dry out fields so farmers could work in them, more rain will negate that effect.

State climatologist Dev Niyogi predicted earlier this year that planting could be postponed because of a wet trend and that Indiana could experience some drying in the growing season, leading to a return to mild to moderate drought conditions across the state. He said that possibility has not changed.

"We don’t have a dominant El Niño or La Niña this year, so the patterns we are seeing from wet to dry could become the highlight of the growing season," Niyogi said.

Even though farmers in Indiana are two weeks behind the five-year average for planting corn, data suggests that the planting date accounts for only 23% of the variability in yields from year to year, says Bob Nielsen, Purdue extension corn specialist.

Tillage and use of herbicides and nitrogen fertilizer are among many yield-influencing factors, or YIFs.

"The good news is that planting date is only one of many YIFs for corn," Nielsen wrote in his online "Chat 'n Chew Café."

Read Nielsen's presentation "Undersatnding Factors that Limit Yield in Corn." (PDF)

Nielsen said that last year 94% of the corn crop was planted by May 15, but it yielded 38% below average, largely because of the drought - a disastrous YIF. Conversely, farmers in 2009 planted only 20% of the crop by that date because of wet conditions, yet their harvest was 9% above trend.

He said that ultimately, farmers still have until mid-May to decide if they need to switch to seeds that would take the crop to maturity faster.

"Let's not succumb quite yet to fear-mongering triggered by the prospects of a delayed late start to corn planting in 2013," Nielsen wrote.

Read more about the planting date conundrum for corn.

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