Monday, September 28, 2015

Beautiful Weather for Drying Corn

The recent high pressure ridge that has settled over Wisconsin has meant millions of dollars to farmers in reduced drying costs. The favorable weather of sunny, warm days with little rain has allowed the 2015 corn crop to dry faster than normal. Last week farmers in northern Wisconsin had corn below 25% moisture.

There is a trade-off though. With high fuel prices and/or low grain prices, it is important to let corn grain dry in the field as much as possible, yet hold harvest losses at a reasonable level. Most corn hybrids mature when the grain has about 30% moisture. Ideally harvest should begin around 25% kernel moisture and be complete by the time grain reaches 20%. Corn ears that are too dry can break from the plant and drop to the ground. Also, kernels can shatter off the ear as they are stripped from the plant by the combine head.

Kernel Moisture Ranges (%) for Harvesting Corn for Various Uses
33-40% Kernel moisture = Silage harvest
29-32% Kernel moisture = High Moisture Corn (ensiled)
25-26% Kernel moisture = Ideal for combining
20-23% Kernel moisture = Ideal for picking
 <  20% Kernel moisture = field losses increase, but cost of drying shell corn is reduced

Once the kernel is mature (black layered) the drydown of corn grain is a simple drying process subject to weather conditions and most consistently associated with degree-days (Hallauer and Russell, 1961). Factors that have been shown to speed the rate of drying include premature death (Troyer and Ambrose, 1971), physical structure of the seed coat or pericarp (Purdy and Crane, 1967), a low number off loose, short husks (Troyer and Ambrose, 1971), and ear angle and date of husk death (Cavalieri and Smith, 1985). Factors not associated with faster drydown were husk and shank characteristics and the shape or size of ears (Crane et al., 1959)

This year it will be even more important because of high yields and the potential for lodging, especially for growers with a long harvest season due to acreage demands. In years past, European corn borer caused increased lodging and ear drop. All are reasons to pay attention to corn harvesting. As harvest is delayed from October to December, losses can increase 5 to 18%. Of course there is always a risk of 100% loss due to a storm or some other bad weather event.

Harvest decisions are affected by the kind of drying and storage facilities available and depends upon the use of the grain. Grain stored for a long period of time (> 1 year) must be dried to less than 14% which is not likely in a field situation, so some artificial drying must occur. Corn stored above 15% moisture is subject to heating from the natural respiration of the grain and molds present. As temperatures rise so does humidity which causes molds, insects and bacteria to grow and decreasing the amount of time that the grain can be stored before it goes out of condition. Regardless of the moisture in stored grain, aeration is needed to control moisture migration.

Further Reading

Wisconsin Corn Agronomy - Grain Harvesting

Eckert, D.J., R.B. Hunter, and H.M. Keener. 1987. Hybrid maturity-energy relationships in corn drying. National Corn Handbook NCH-51.

Nichols, T.E. 1988. Economics of On-Farm Corn Drying. National Corn Handbook NCH-21.

Literature Cited

Cavalieri, A.J., and O.S. Smith. 1985. Grain Filling and Field Drying of a Set of Maize Hybrids Released From 1930 to 1982. Crop Sci. 25:856-860.

Crane, P.L., S.R. Miles, and J.E. Newman. 1959. Factors Associated with Varietal Differences in Rate of Field Drying in Corn. Agron. J. 51:318-320.

Hallauer, A.R., and W.A. Russell. 1961. Effects of selected weather facttors on grain moisture reduction from silking to physilogic maturity in corn. Agronomy Journal 53.

Purdy, J.L., and P.L. Crane. 1967. Influence of pericarp on differential drying rate in "mature" corn (Zea mays L.). Crop Science 7:379-381.

Troyer, A.F., and W.B. Ambrose. 1971. Plant Characteristics Affecting Field Drying Rate of Ear Corn. Crop Sci 11:529-531.

Monday, September 21, 2015

Down Corn

The August and September USDA-NASS yield estimates indicate that Wisconsin corn farmers are on-track to produce a record yielding corn crop. We are starting to see lodging issues at Arlington as silage harvest begins. Some lodging is due to an earlier wind event occurring around V10 to V12 that flattened plants and caused them to 'snake' back up. However, high yields in and of themselves can cause lodging issues.

For a corn plant to remain healthy and free of stalk rot, the plant must produce enough carbohydrates by photosynthesis to keep root cells and pith cells in the stalk alive and enough to meet demands for grain fill. When corn is subjected to stress during grainfill, photosynthetic activity is reduced. As a result, the carbohydrate levels available for the developing ear are insufficient. The corn plant responds to this situation by removing carbohydrates from the leaves, stalk, and roots to the developing ear. While this "cannibalization" process ensures a supply of carbohydrates for the developing ear, the removal of carbohydrates results in premature death of pith cells in the stalk and root tissues, which predisposes plants to root and stalk infection by fungi. As plants near maturity, this removal of nutrients from the stalk to the developing grain results in a rapid deterioration of the lower portion of corn plants in drought stressed fields with lower leaves appearing to be nitrogen stressed, brown, and/or dead.

Other plant stresses which increase the likelihood of stalk rot problems include: loss of leaf tissue due to foliar diseases (such as gray leaf spot or northern corn leaf blight), insects, or hail; injury to the root system by insects or chemicals; high levels of nitrogen in relation to potassium; compacted or saturated soils restricting root growth; and high plant populations.

For some ideas on how to handle down corn, click here.

Further Reading

Carter, P.R. 2015. Wind Lodging Effects on Corn Growth and Grain Yield. Pioneer Insights, click here.

Carter, P.R., and K.D. Hudelson. 1988. Influence of simulated wind lodging on corn growth and grain yield. J. Prod. Agric. 1:295-299.

Nielsen, B., and D. Colville. 1988. Stalk Lodging in Corn: Guidelines for Preventive Management. Agronomy Guide, AY-262 Purdue University, West Lafayette, IN

Monday, September 14, 2015

High Moisture Corn and By-Products

As we move into the 2015 harvest season, many growers harvest high moisture corn for feed. The following is a summary of a publication on High Moisture Grain and Grain By-Products,

High moisture corn is, as the name implies, corn harvested before the kernels dry down, usually processed by a roller mill or hammer mill, packed into an appropriate structure and allowed to ferment. High moisture ear corn is similar to high moisture corn but it includes some portion of the cob. Snaplage includes the grain, cob, and shuck (husk leaves and shank).

Preservation of high moisture grains and grain by-products is a common practice for feeding livestock in most temperate regions of the world. High moisture storage of grain has been driven by the savings of not having to dry grain at  harvest. The moisture content of most high moisture grain is within the range of 20 to 35%, and the storage time required is usually no more than the time interval between harvests, or up to 12 months. For grain by-products, where the moisture content is much greater, the pressure for high moisture storage is also driven by cost savings. However, storage of by-products is usually for short periods of time only.

As with forages, the anaerobic fermentation during ensiling of these products is based primarily on lactic acid, but amounts produced are variable both between batches of ensiled high moisture grain and even during the storage of any given batch. Not surprisingly, ethanol is found in ensiled grain. Differences in pattern of acid and ethanol production in grain may be attributed to moisture content and form of the grain. Ensiled high moisture grains and grain by-products are prone to considerable aerobic deterioration with post-storage exposure to air. Of the potential additives to facilitate storage, propionic acid is the most successful, although it is used only when the material stands a risk of significant exposure to air during storage. Results from inoculation of high moisture grains and by-products with bacteria are inconclusive, but recent studies with bacteria producing propionic acid show promise. Recovery of dry matter and nutrients after ensiling grain and by-products is usually more than 90% and for grains is usually optimized by storing the grain in sealed structures and at a moisture content between 25 and 30%.

High moisture grains usually contain the same amount of available energy for pigs and ruminants as the corresponding dry grain. In a recent comprehensive review of feeding grains to beef cattle, it was found that high moisture corn and sorghum were not as efficiently utilized as the corresponding steam rolled dry grain. For lactating dairy cows, however, high moisture grain is used as efficiently, if not more efficiently, than the corresponding dry grain. High moisture storage of grains and by-products does not usually affect food intake.

For Further Reading:

Buchanan-Smith, J., T.K. Smith, and J.R. Morris. 2003. High Moisture Grain and Grain By-Products, p. 825-854, In D. R. Buxton, R. E. Muck and J. H. Harrison, eds. Silage Science and Technology. American Society of Agronomy, Crop Science Society of America, Soil Science Society of America.

Hoffman, P.C., R.D. Shaver, and N.M. Esser. 2010. The Chemistry of High Moisture Corn. Proc. 2010 4-State Dairy Nutrition & Management Conf., Dubuque, IA.

Wisconsin Corn Agronomy - HMC, HMEC and Snaplage