(Guthrie Center, Iowa) – Corn and soybean yield potential in southwestern Iowa is below expectations due to very dry soils and late maturity, crop scouts on the western leg of the Pro Farmer Midwest Crop Tour say.
One route on the western tour figured average corn yield in the region at 139.7 bushels/acre, down from last year's tour average for the region of 153.8 bushels/acre. Nine fields were sampled Wednesday morning on the route through the southwest corner of the state with a yield range of 67 to 217.
Denitrification due to shallow root systems was seen as a common problem weighing on yield potential.
"It's definitely below what I expected,” says Gary Wietgrefe, tour participant and certified crop advisor with Syngenta Seeds in Sioux Falls, S.D. "I thought they had enough moisture and hills that wouldn't cause problems with the corn, but the heavy rains earlier in the season kept the roots shallow and now the top is drying out.”
Very dry soil was noted in nearly all fields sampled along the route. The dryness is an even greater threat for the soybean crop, scouts say. Pod counts in a three-foot by three-foot square averaged 1,037 pods, down from 1,321.5 pods sampled last year for the same region. Pod counts ranged from as low as 77 to 1,930.
Of chief concern for the soybean crop in the region is the late maturity with such dry soils. Many fields along the route were still in the flowering stage, signaling a very immature crop resulting from replanting in the region due to excessive rains earlier in the season.
"I think it's dangerous to draw a lot of conclusions (on yield) when you're looking at beans so young,” says Russ Day, tour participant and hedge fund manager for Glencore, Ltd., in Stanford, Conn.. "I think the old saying still holds true. August rain is what matters. You can still make or break a crop.”
If Iowa does not get the rains it needs in the weeks ahead, Day says, USDA's yield estimate for the state could be too high. However, if rains start falling soon and continue as pods fill, yield could even be above average.
"The rain is what I care about,” Day says. "All these plants are throwing pods up. It's a matter of filling them.”
USDA currently figures Iowa's soybean yield at 41.0 bushels/acre with total production pegged at 165.6 million bushels, up from last year's crop of 133.6 million.
The western leg of the Crop Tour will meet this evening in Spencer, Iowa before concluding Thursday in Austin, Minn.