Continued Dry Weather Is Hurting Iowa Corn Crop

Less than half of the state's corn and soybean crop is in good to excellent condition.

Published on: Aug 20, 2013

Iowa's corn crop has tasseled, but it isn't as far along in development as it is in an average year. That's what the weekly Iowa Crops & Weather report issued by USDA on August 19 indicates. Based on statewide surveys as of August 18, the report shows less than half of Iowa's corn and soybean crop is in good-to-excellent condition.

Rain fell in some areas of Iowa during the week ending August 18, but many areas remain quite dry. And corn in those driest parts of the state, especially on fields with lighter soils, is starting to show some firing. Cooler than normal weather the past four weeks has helped Iowa corn and soybean crops withstand dryness and lack of rain--but the weather forecast for this week and next week is for "hot and dry."

RAIN IS NEEDED: Some parts of Iowa got a nice shower last week, but most areas that need rain didnt get any. Corn plants in some fields are beginning to fire in the driest areas of the state. Leaves near the bottom of the plant are turning brown and dying. Condition of the Iowa corn crop dropped slightly in the past week. As of August 18 corn statewide is rated 40% good and 8% excellent. Soybeans are 38% good and 9% excellent.
RAIN IS NEEDED: Some parts of Iowa got a nice shower last week, but most areas that need rain didn't get any. Corn plants in some fields are beginning to fire in the driest areas of the state. Leaves near the bottom of the plant are turning brown and dying. Condition of the Iowa corn crop dropped slightly in the past week. As of August 18 corn statewide is rated 40% good and 8% excellent. Soybeans are 38% good and 9% excellent.

"What happens with the weather this week and next week is going to be very important," says Roger Elmore, Iowa State University Extension corn agronomist. "The kernels on the ears are filling now, and kernel weights could end up being reduced if the plants don't have adequate moisture." Corn in Iowa came through pollination pretty good, although the late planted corn is just now pollinating. But kernel fill during these last two weeks of August and in early September will make a difference in yield.

A key consideration is Iowa's corn crop this year isn't as deep-rooted as corn was last year

The state pulled out of a drought earlier this year and farmers had to fight flooding and delayed planting in the spring. Then things got dry again, and also cooler than normal, during July and August. Some analysts are expecting better yields in 2013 than last year's drought-reduced crop produced, but it's still unclear how much better. And depending on weather during the next two weeks—August 19 to September 2 or so—yield potential may end up getting hurt if most of Iowa continues hot and dry.~~~PAGE_BREAK_HERE~~~

"One consideration is that we have a crop this year that's not rooted as deep as the corn was last year," points out Elmore. "A shallow root system doesn't help during dry weather as plants can't reach down deep enough to get to the deeper subsoil moisture to carry them through periods when there is lack of rain."

Week ending August 18 was sixth week of the past seven to bring less than normal rainfall

As of August 18, the weekly USDA survey shows 65% of Iowa's topsoil and 59% of the subsoil is short to very short on moisture. "The dry weather remains a concern," notes Iowa Secretary of Agriculture Bill Northey. "While the cool, dry weather was ideal for the Iowa State Fair, crops now need additional precipitation and warm weather as development remains well behind the five-year average."

The complete weekly report is available on the Iowa Department of Agriculture & Land Stewardship's site or on USDA's site.  The report summary follows here:

Lack of rain this summer remains a growing concern for many Iowa areas

CROP REPORT: Drier and cooler than average weather persisted across most of Iowa during the week ending August 18, 2013, according to the latest survey by USDA's National Agricultural Statistics Service. Although varying amounts of moisture were received in central and western portions of the state, the lack of significant precipitation remains a growing concern for many Iowa farmers. Statewide there was an average of 6.4 days suitable for fieldwork. Southwest Iowa received the most rainfall during the week, and had the least days suitable for fieldwork with 5.8 days.

A total of 35% of Iowa's topsoil and 41% of the subsoil was in the adequate and surplus moisture categories on August 18, both declining 6 percentage points from the previous week. Topsoil moisture levels are now rated 25% very short, 40% short, 34% adequate and 1% surplus. Subsoil moisture levels are rated 19% very short, 40% short, 40% adequate and 1% surplus.

About 24% of Iowa's corn crop has now reached dough stage, normal is 60%

With nearly all the corn crop tasseled, 93% was silking as of August 18, which is behind the 5-year average of 99%. Sixty-two percent of the corn crop has reached the milk stage, trailing the normal 87%. Twenty-four percent of the crop has reached the dough stage, well behind the normal 60%. Some of the very earliest planted corn has reached the dent stage. Corn condition statewide on August 18 declined slightly from previous week, and is rated at 5% very poor, 13% poor, 34% fair, 40% good and 8% excellent.~~~PAGE_BREAK_HERE~~~

With 95% of the soybean crop blooming on August 18, pods were being set on 71% of the soybean crop, well behind last year's 94% and the normal 89%. Soybean condition declined slightly from last week and is now rated 5% very poor, 12% poor, 36% fair, 38% good and 9% excellent. Oat harvest on August 18 was wrapping up across Iowa.

The third cutting of alfalfa has reached 36% compete, 9 days behind the normal pace. Both hay and pasture conditions continued to deteriorate during the week ending August 18, and the amount rated in the good and excellent categories fell 4 and 3 percentage points, respectively. Hay condition is rated at 5% very poor, 13% poor, 36% fair, 40% good and 6% excellent. Pasture condition is rated 10% very poor, 22% poor, 40% fair, 25% good and 3% excellent.

Unseasonably cool weather prevailed last week; most of Iowa is still waiting for a substantial rain

IOWA PRELIMINARY WEATHER SUMMARY—for week ending August 18, 2013

By Harry Hillaker, State Climatologist, Iowa Department of Agriculture & Land Stewardship

Unseasonably cool weather prevailed for another week while most of the state is still waiting for a substantial rain. Temperatures averaged below normal every day during the week ending August 18, as they have for all but one day in the past four weeks.

Temperatures approached normal on Sunday (Aug. 11) and Monday (Aug. 12) with highs mostly in the 80's but they were well below normal from Tuesday (Aug. 13) through Thursday (Aug. 15) when daytime highs were mostly in the 70's. Temperature extremes for the week ranged from Sunday (Aug. 11) afternoon highs of 88 degrees at Bloomfield, Centerville, Des Moines, Donnellson and Osceola, as well as at Red Oak on Monday to Wednesday morning lows of 42 degrees at Elkader and Belle Plaine. Temperatures for the week as a whole averaged 5.9 degrees below normal.

Temperatures for week ending August 18 averaged 5.9 degrees below normal

Thunderstorms brought very welcome rain to parts of north central and central Iowa on Sunday (Aug. 11) night with a maximum reported amount of 2.27 inches at Boone. Rain was also widespread across the southwest one-third of the state on Wednesday night with Underwood (Pottawattamie Co.) reporting the most with 3.85 inches. However, parts of the state, particularly the far southeast, received no rain for the week. The statewide average precipitation was 0.44 inches while normal for the week is 0.98 inches. The week ending August 18 was the sixth week of the past seven to bring less than normal rainfall.