Drought and dry weather expanded across most of Iowa last week. USDA’s weekly survey results released Aug. 31 show Iowa’s corn crop rating fell to 45% in the good-to-excellent category, down 5% from the previous week. Only 3.7% of the state is drought-free, USDA reports. While Iowa continues to see the worst conditions in the Corn Belt, other key crop-producing states also saw a degradation in conditions at the end of August.

“In west-central Iowa, we have a crispy drought, and corn and soybeans are maturing quickly,” says Mike Witt, Iowa State University Extension field agronomist. “Corn was hard-hit by the derecho windstorm on Aug. 10, and dry weather since then has taken its toll. Unfortunately, the corn has not stood back up.”

Soybean fields turn yellow

The soybean crop in west-central Iowa last week showed quick deterioration. “With the hot temperatures, we saw a number of soybean fields go from being green to yellow within four days,” Witt says. “That heat didn’t do us any favors in the bean fields. With the lack of moisture in the soil, we will see smaller beans in the pods, and many plants will have fewer pods than usual. This has hurt the soybean yield potential across many fields in west-central, central and into eastern Iowa.”

“Iowa saw hot and dry conditions last week, though portions of the state did receive some rainfall along a cold front that brought cooler temperatures over the weekend,” says Iowa Ag Secretary Mike Naig. “Short-term outlooks for early September suggest cooler temperatures and chances of more widespread rainfall, both of which would help ease the expanding drought conditions.”

The complete weekly Iowa Crop Progress and Condition report is available on USDA’s site at nass.usda.gov/ia.

Crop report

Continued dry weather allowed Iowa farmers 6.7 days suitable for fieldwork during the week ending Aug. 30, according to USDA’s National Ag Statistics Service. Drought conditions and rapidly drying crops are now a concern for most of Iowa. Field activities included harvesting hay, chopping corn silage and harvesting seed corn. Some farmers have been cleared to mow or disk their corn damaged by the derecho.

Topsoil moisture condition is rated 41% very short, 40% short, 19% adequate and 0% surplus. The state’s topsoil moisture condition has deteriorated to 81% short to very short. Subsoil moisture condition is rated 37% very short, 40% short, 23% adequate and 0% surplus. Iowa’s subsoil moisture condition has dropped to more than three-quarters of the state now being short to very short.

The Iowa corn crop as of Aug. 30 is 95% in the dough stage or beyond, over two weeks ahead of the previous year and six days ahead of the five-year average. Almost three-quarters of the corn crop is in or beyond dent stage, over two weeks ahead of the previous year and one week ahead of average.

The crop seems to be speeding towards maturity with 11% of the crop mature, 18 days ahead of last year and six days ahead of average. Corn condition is rated 45% good-to-excellent, a drop of 5% from the previous week and the lowest level since the week ending Oct. 20, 2013.

Soybeans setting pods are over two weeks ahead of last year and four days ahead of average at 96%. Soybeans coloring (green plants turning yellow as they head to maturity) have reached 29% as Aug. 30. That’s the highest percentage of soybeans coloring by Aug. 30 since 2012. Soybean condition fell again last week with the crop now rated 50% good-to-excellent, the lowest level so far this season.

Alfalfa hay third cutting is now 86% complete, almost three weeks ahead of last year and 11 days ahead of the five-year average. Pasture condition fell 7 percentage points last week to just 16% good-to-excellent. Many cattle producers have had to begin supplemental feeding of hay due to deteriorating pasture conditions.

Weather summary

The week Aug. 24-30 was the driest reporting period of this summer and of the 2020 growing season thus far. “All Iowa stations, except for one, reported below-average precipitation, with deficits near an inch at rain gauges in eastern Iowa,” says Justin Glisan, state climatologist with the Iowa Department of Agriculture. “Much of last week also had temperatures well above average, with the highest departures on the order of 10 to 12 degrees above normal in western Iowa. The statewide average temperature was 77.3 degrees, 6.1 degrees above normal.”

Weekly rainfall totals ranged from no accumulation at more than half of Iowa’s stations to 1.68 inches in Monticello (Jones County). The statewide weekly average precipitation last week was 0.11 inch while the normal is 0.96 inch. Several stations reported the week’s high temperature of 99 degrees F on Aug. 24, on average 18 degrees above normal. Chariton (Lucas County) reported the week’s low temperature of 44 degrees on Aug. 30, which is 13 degrees below normal.

U.S. crop ratings slip

Looking at the national picture, the U.S. corn and soybean crops for 2020 continue to record poor ratings from week to week, according to USDA’s survey. In its report for the week ending Aug. 30, USDA’s estimate of corn having a good-to-excellent rating is 62%, versus 64% a week ago. The Iowa corn crop, as of Aug. 30 has a good-to-excellent rating of 45%, compared with a 70% rating for Illinois, 79% for Minnesota, 64% for Nebraska and 80% for Wisconsin’s corn.

Meanwhile, 94% of the nation’s corn is dough stage, versus an 89% five-year average. USDA pegs the U.S. corn crop as 63% dented, versus a 56% five-year average. The USDA has pegged the U.S. corn as 12% mature, above a 10% five-year average. USDA says 95% of the nation’s soybean crop is now in the “setting pods” stage, ahead of the 93% five-year average. And 8% of the U.S. soybean crop is dropping leaves, versus an 8% five-year average for the Aug. 30 date. USDA estimates the soybean good-to-excellent rating is 66%, versus 69% a week