Near record warm September
Corn dry-down rates
Avoid harvest losses
Weather comments
Take the soybean aphid treated vs. non-treated yield survey

Introduction
Harvest of the soybean crop is well underway with excellent harvest conditions (so far).  Harvest of high moisture corn has also started.  Yield reports in both crops look to be very good at this point.  As you begin the harvest season, pay close attention to potential machinery and moisture harvest losses.  Be sure all equipment is properly calibrated and pay close attention to grain moisture.  Taking the extra few minutes to fine tune harvest and drying equipment will quickly pay for itself.  And most importantly, pay close attention to safety in and around harvesting equipment, on the road, and at the farm site.

Row-Crop and Forage Information
Growing Degree-day It appears that the month of September will record more degree-days than August (498 vs. 472).  September (2004) will also record the 2^nd most degree-days for this month in the last 13 years.  Only 1998 produced more degree-days in September, yielding 536 DD Last week, 109 degree-days were recorded, much above the average of 52.  A cooler week is forecasted with an estimated 42 degree-days to be recorded over the next 7 days.  Seasonal total degree day accumulations for April and early May planting dates continue to improve when compared to the 13-year average (93 to 96% of normal).  West-Central IA will end the season with about 150 degree-days below normal.  Degree-days (average for NW Iowa) can be accessed at this web site:  http://www.extension.iastate.edu/carroll/crops/degree-days-2004.htm

Table 1.  Degree-Day Weekly Accumulation
	2004	2003	2002	13-Yr Ave
Sept 20 - 26	109	60	49	52
Forcasted Sept 27 - 03	42

 

	Table 2.  2004 Degree-Day % of Average (by planting date)
	10-Apr	15-Apr	20-Apr	25-Apr	30-Apr	05-May	10-May	Ave
last week	96%	96%	95%	95%	94%	95%	93%	95%
this week	96%	96%	95%	95%	95%	95%	93%	95%

Corn development  Most corn across the region has reached physiological maturity.  Harvest of high moisture corn for feed has occurred and early yield reports appear to be very positive. 

Dry down rates of corn.  Once physiological maturity has been reached, the rate of in-field dry down will determine when harvest maturity is reached.  Corn specialists from several Midwestern states (Peter Thomison from Ohio State University, Dale Hick; University of MN, and Bob Nielsen; Purdue) describe corn dry-down rates as follows:

• Corn will normally dry approximately 3/4 to 1 point of moisture per day during favorable drying weather (sunny and breezy) during the early warmer part of the harvest season from mid to late September.

• Early to mid-October, dry-down rates will usually drop to 1/2 to 3/4% per day.

Estimating dry-down rates can also be considered in terms of Growing Degree-Days (GDDs). It takes about 30 GDDs to lower grain moisture each point from 30% down to 25%. Drying from 25 to 20 percent requires about 45 GDDs per point of moisture.
* Dry down rates were derived from studies in other states, therefore they may be different for west IA, but they are a good baseline to work from.

Estimated Corn "In-Field" Dry-Down
	Current Moisture Between
	30% - 25%	25% - 20%
	Moisture lost (%)
Last Week	3.6	2.4
This Week	1.4	0.9

Additional discussion of corn dry-down can be obtained from a 2001 article prepared by Dr. Bob Nielsen, extension agronomist at Purdue - in the "Chat n' Chew Café."  It's available on-line: http://www.agry.purdue.edu/ext/corn/news/articles.01/Grain_Drydown-0826.html

Harvest losses – rules of thumb.

Corn Harvest Losses

• 2 kernels per sq. ft. equal one bu/a loss.

• One ear per 125 ft of 30-in row equals one bu/a loss.

• One ear per 100 ft of 38-in row equals one bu/a loss.

Soybean Harvest Losses

• 4 soybeans per square foot equal one bu/a loss.

• Be sure to include soybeans in uncut stubble.