"This sounds like a broken record, but we are looking at yet another harvest driven by weather extremes and combinations that are hard to predict," observes Charles Hurburgh, Iowa State University grain quality specialist and director of the Iowa Grain Quality Initiative. The major events that have set the stage for this year's widely variable harvest in Iowa were the extremely late planting in very wet soils, followed by an almost complete turnaround in many places to a steadily growing drought condition.
"In July, the market believed that our major harvest risk would be very wet and late crops vulnerable to even an average frost," notes Hurburgh. "By September 1, protracted heat changed the picture completely to the point where corn harvesting had already begun in several markets. The quality and management forecast now differs sharply between corn and soybeans." Hurburgh offers the following information and recommendations for harvesting, handling and drying the 2013 Iowa crop.
Corn—grain moisture variation will be an issue this year, even with the same planting date
The recent extension of 90+ degree temperatures with inadequate rainfall has rapidly increased maturity of corn regardless of planting date. This demonstrates the principle that timing of events is at least as important as the average conditions. On average this year Iowa had "average" temperature and rainfall. However, corn quality is driven by conditions during grain fill. Kernels are small and shallow; the extent of kernel fill will be variable depending on timing of rains.
Last year drought-stressed plants put unexpectedly large amounts of dry matter into kernels, resulting in the highest test weights and protein contents in many years. Areas that had enough rainfall to continue root development in June and July of 2013 may experience the same result, but this year we have shallower rooted plants and they will likely have reduced grain fill and, therefore, lower test weights.~~~PAGE_BREAK_HERE~~~
Test weight is one of two reliable indicators of storability, the other being the variation in grain moisture at harvest. Moisture variation will be an issue this year; even within the same planting date, there are large differences in corn maturity within fields or even the same rows. If there are large areas of replants, harvesting around them is a good option, but within fields there is little choice but to harvest straight through, which creates challenges for drying and handling. Recognize that early harvest will happen in warm weather. Rapid drying and cooling of harvested corn will be critical to preserving the storage life of 2013 corn. The actions you take in the first few days after harvest can either preserve or waste the future storage life of grain.
Soybeans—the beans in the pods are smaller than normal this year
Soybeans are small but will probably be dry, except those fields that were planted quite late (June and after). Late-planted soybeans may still have some frost risk, especially in areas that received enough rain in August and early September to slow down the maturing process. Growth in the late part of the growing season will mean harvesting with green stems and mixed quality. ISU Extension will have more information on frost impacts and handling of frost damaged soybeans -- if this problem occurs.
Harvest planning and preparation—scout fields for ear molds on corn
Scout fields for fungal infections. Until the very recent hot weather, fungus and related mycotoxin problems seemed unlikely. However, deteriorating conditions and repeated small rains may encourage field fungi. It is important to understand which fungus can produce which toxin. There is a video tutorial on mycotoxins on the Iowa Grain Quality Initiative website.
Scouting for ear rots—cornfields should be watched carefully
Fields should be scouted for ear rots from black layer development onward. (See Figure 1 accompanying this article). At several locations in a field, peel back the husks of several ears and examine the ear for signs and symptoms of ear rot. Take note of what ear rot is present. If more than 10% of the ears in the field have ear rot, the field should be scheduled for harvest as soon as possible. This is particularly important in the case of ear rots that are associated with mycotoxin production (Aspergillus, Fusarium and Gibberella). Wet weather after maturity while the grain is drying down may increase the risk of toxin production by favoring growth of the fungus.~~~PAGE_BREAK_HERE~~~
Figure 1. Corn ear molds may be a problem in some fields this fall. This is particularly important in the case of ear rots that are associated with mycotoxin production (Aspergillus, Fusarium and Gibberella).
Grain management—how you handle the grain within the first few days after harvest will be very important
Following basic principles of grain management will be important; the high variability in quality will not leave much room for error.
* Immediate cooling after harvest (and drying) - shelf life begins right away.
* Have adequate aeration (0.1 cfm/bu or more) - all bins with all grains should be aerated.
* Run a cooling cycle every 10 to 15 degree average change in outside temperature, starting at harvest. With 0.1 cfm/bu, a cooling cycle will take about 150 hours; proportionately less for higher airflows.
* Get grain below 40 degrees F as quickly as possible.
* Take out the center core of fines. Variable quality and lower test weight will mean more fines.
* Inspect grain and monitor temperature weekly until December; every two weeks thereafter. Automated temperature cable systems are very useful; the larger the bin the less likely a manual check will be adequate.
* Responding to temperature change is as important as the actual temperature. A 3 to 5 degree change between readings, even if from 40 to 45 degree F, is indicative of spoilage if the fan had not been run in the interim.
* Stay within temperature-moisture guidelines. These are listed in the accompanying table. (See Figure 2.)~~~PAGE_BREAK_HERE~~~
Figure 2. Maximum storage time for corn and soybeans
Operating suggestions—steps you can take to help preserve the quality of your corn and soybean crop
* Recalibrate your yield monitor.
– Seed size and density are factors in yield monitor response.
* Take more than one moisture sample any time moisture is being measured.
– Average of at least three separate samples
* Check dryer moisture often (out and in)
– This applies especially to continuous flow and automated batch dryers.
* Check accuracy on freshly dried grain.
– Freshly dried grain normally reads low; test 5 to 10 sealed samples 4 to 6 hours later to establish a rough correction factor.
* Keep good records on what grain went where.
– Tracking of wet grain can indicate where problems could occur later.
– Crop insurance records often need traceability by unit.
* Separate by test weight.
– Check each new field as you open it.
– Sell light grain first and grain that clearly had large moisture variations.
– The yield monitor moisture will give a good indication of high variability.
* Expect hot spots to occur in grain in storage bins.
– No dryer can completely even out wide moisture variances.
– February and March will be the most likely time that problems will arise.
– Good temperature systems are needed to detect hot spots deep in large bins.
* If you have late planted corn or replanted corn in spots within a field, drive around them and come back later and harvest them.
– Moisture will be higher and test weight will be lower.
* Take out the center core of fines in all bins.
– Variable quality and lower test weight will mean more fines.
– Fines disrupt and restrict airflow.