Q: How have early October rains and cooler temperatures affected corn drydown? Is it slower than normal?

 

View season long GDDs for 20 sites at gdd-etdata

Oct. 14, 2015

Drydown slows after leaves die due to natural senescence, disease, or frost/freeze. This stops plant respiration, leaving only evaporation to remove moisture from the corn, said Tom Hoegemeyer, UNL professor of practice in agronomy and Nebraska corn breeder. In addition, saturated soils tend to increase "local" relative humidity in the field, especially with still days.  Corn can even re-absorb water from rainfall if water gets into husks, although ears on most hybrids turn down at maturity and are less apt to capture rain.

It takes an average 25 GDD to dry down corn 1 percentage point. That number can range from 15 to 35 GDD, depending on cloud cover, relative humidity, and wind. Compared to states east of us, Nebraska's lower humidity and high winds are significant advantages when it comes to drydown, Hoegemeyer said, and sunshine, even on cold days, will tend to continue drying corn.

The following data reflects accumulated GDD from Oct. 1 through Oct. 13, 2014. While GDD accumulation for the period is behind normal for most sites, a few sites in southwest and western Nebraska are ahead of normal. With the onset of warmer, drier conditions this weekend State Climatologist Al Dutcher  expects to see the difference between current and normal GDDs reduced by 5-10 units in western Nebraska and about 5 units in eastern Nebraska.

"If forecasts are correct, we should accumulate 50-60 additional units across eastern Nebraska through Monday and 60-70 units in western Nebraska," Dutcher said.

 

Growing Degree Day Summary
	Crop Ref	Accumulated GDDs
	(10/1-10/13)			(10/1-10/23)
		Actual 2014	Normal	Actual 2014	Normal
AINSWORTH	Corn	107	113	223	175
ALLIANCE	Corn	106	110	217	171
ARTHUR	Corn	105	115	220	179
BARTA	Corn	97	113	201	177
BEATRICE	Corn	112	129	226	204
BRULE	Corn	119	117	248	184
BRUNSWICK	Corn	89	111	185	170
CEDAR POINT	Corn	109	118	231	184
CENTRAL CITY	Corn	120	118	232	185
CHAMPION	Corn	124	124	253	170
CLAY CENTER	Corn	113	122	221	192
CONCORD	Corn	88	113	187	174
COZAD	Corn	124	122	241	192
CURTIS	Corn	117	124	233	195
DICKENS	Corn	113	120	233	189
ELGIN	Corn	102	113	203	175
FIRTH	Corn	117	129	243	204
GORDON	Corn	90	112	198	173
GOTHENBURG	Corn	116	122	229	193
GRAND ISLAND	Corn	109	119	212	187
GUDMUNDSEN	Corn	91	115	195	180
HALSEY	Corn	104	115	214	179
HIGGINS RANCH	Corn	104	111	216	172
HOLDREGE	Corn	116	123	222	195
INDIAN CAVE	Corn	105	129	224	205
KEARNEY	Corn	110	121	214	191
LEXINGTON	Corn	111	123	220	195
LINCOLN	Corn	104	129	219	204
MCCOOK	Corn	127	124	254	195
MEAD	Corn	102	125	213	197
MERNA	Corn	118	118	233	184
MERRITT	Corn	105	114	223	178
MINDEN	Corn	112	122	217	193
MITCHELL FARM	Corn	109	114	222	179
MONROE	Corn	108	119	218	186
NEBRASKA CITY	Corn	102	128	215	203
NEWPORT	Corn	103	111	212	172
NORTH PLATTE	Corn	119	120	240	189
OAKLAND	Corn	102	116	215	181
O'NEILL	Corn	91	114	189	177
ORD	Corn	109	117	218	182
RED CLOUD	Corn	117	123	231	195
SCOTTSBLUFF	Corn	118	111	237	173
SHELTON	Corn	111	122	215	192
SIDNEY	Corn	101	114	208	178
SMITHFIELD	Corn	113	123	223	194
WEST POINT	Corn	93	122	195	192
YORK	Corn	113	124	225	196