Corn Storage - Wisconsin Corn Agronomy

The safe level for ear corn in the crib is higher than for shelled corn because air passes through to remove heat and to dry the corn. In northern corn growing areas, the upper limit in narrow cribs (4 1/2 feet) is about 25% moisture in the grain. If late fall and winter are so damp that grain does not dry, spoilage will begin with the onset of warm weather in the spring. In the central Corn Belt where cribs are wider in order to handle higher yields, the safe limit is about 20%. Corn should be down to 18.5% by March 1 to avoid spoilage with the onset of warm weather.

Narrow cribs: 5-6 ft width - moisture % no higher than 22-23%
Wide cribs: 7-8 ft width - moisture % no higher than 20-22%
Recommended crib width is narrower in northerly areas of the CORN BELT

HIGH MOISTURE CORN (HMC)

Estimating the Value of Wet Ear Corn--A Suggested Starting Point UWEX Bulletin A3410
Usually harvested at 28-32% kernel moisture
Equivalent Price/Ton of High Moisture Ear or Shelled Corn vs Price per Dry Bushel: conversion tables for converting wet ear corn and wet shelled corn to its dry corn price equivalent. Developed by Jeff Key, Winnebago County and Gary Frank, Center for Dairy Profitability

Advantages of HMEC over HMSC

Can harvest 15-20% more feed/acre with HMEC than with HMSC
Milk production/lb of feed is slightly better for HMEC
Cows don't go off feed as often with HMEC

Advantages of HMC over conventional harvesting

No Drying Costs
Earlier harvest
Spreads work load
Reduces harvest losses
HMC is more palatable than dry corn

Handling and processing of HMC for good packing and fermentation

95% of the kernels should be cracked or broken
Cob pieces shouldn't be larger than 1/2-inch in diameter
Grinding too fine will result in floury HMC

Dry Shell Corn Storage

A bushel of corn at 15.5% moisture consists of 47.32 pounds of dry matter and 8.68 pounds of water.

Shrink

Grain moisture is calculated on a wet basis:

Percent moisture =	100 x (wet weight - dry weight)
	wet weight

When grain is dried there is less weight of dry grain:

Percent shrinkage = 1 -	{	(100 - Corn moisture initial)	}	x 100
		(100 - Corn moisture final)

For example: 850 bushel truck load delivered at 23% moisture and is dried to 15%

1 -	{	(100 - 23)	}	x 100 = (1 - {77/85}) x 100% = 9.41%
		(100 - 15)

Thus, the farmer would have delivered 850 bushels x 0.0941 = 80 "bushels" of water and 770 bushels of corn at 15% moisture.

Usually a 0.5% "handling" shrink is also added to "moisture" shrink due to:

"beeswings"
dust
general elevator experience

This would bring the total shrink to 9.41% + 0.5% = 9.91%

Many elevators use a shrink of 1.3 or 1.4 percent per point of moisture above the base market moisture. For this example:

23% - 15% = 8%

8% x 1.3 = 10.4% shrink

8% x 1.4 = 11.2% shrink

Drying and shrink charges vary by elevator and time during the season.

Typical drying charges range from 1.5 to 4 cents per point per bushel above 15% moisture.

Drying and shrink charges used by elevators often provide incentive for growers to dry their own grain.

Calculating Grain Weight Shrinkage in Corn Due to Mechanical Drying National Corn Handbook - 61

Drying Systems

Minimize moisture migration, storage diseases, and insect damage

Dry to 13% for safe, long term storage

Closed loop drying system

Short bins: wet grain is dried
Tall bins: dry grain is stored

Shiver drying system

Drying bin - Corn dried to 15 % moisture with forced, heated air
Storage bins - Corn dried from 15 % moisture down to 13%
Corn is augured from drying bins to storage bins automatically

Low temperature drying system

Uses unheated air or slightly-heated air
Depends upon outside temperature and airflow

Temperatures at which to dry corn

Continuous flow = 180 to 220 F
Corn to be used for wet milling, not exceed 140 F
Corn used for dry milling, not exceed 110 to 120 F
High temperatures reduce test weight, discolor kernels, denature protein, gelatinize starch and increase stress cracks

Recommendations for grain drying air flow by region:

The eastern and southern portions of the region need higher air flows because of higher humidities and somewhat warmer temperatures at harvest.

Hazards of Grain Drying Systems

(From MWPS-13 Grain Drying, Handling and Storage Handbook, 1987.)

A 200-lb human with a density of approximately that of water has a volume of approximately:
200 lb / (62.4 lb/cu.ft.) = 3.2 cu.ft. If the grain flow out of the bin is 1500 bu per hour, that is equivalent to 1500 bu x 1.244 cu ft/bu x 1/3600 hr/s = 0.518 cu ft/sec. So the human, if he/she is at the center of grain flow, will be buried in the grain in 3.2 cu ft/(0.518 cu ft/s) = 6.17 seconds.

Storage requirements - shell corn

Length of time depends upon temperature and humidity of grain

Temperature:

Keep grain temp close to outside air temp
Cool with fans in late fall
Warm with fans in early spring

Remove fines

Worst problem in stored grain
Inhibit air flow and cause heating
Easiest for insects and diseases to attack

Temporary Grain Storage Tips

Picking sites that are elevated and have good drainage is the key to storing grain on the ground. The risk of crop loss is higher when grain is stored on the ground than in bins, so ground piles should be considered short-term storage and monitored frequently.

The success of storing grain on the ground depends on a combination of variables that can be controlled, such as site preparation, storage design, use of aeration and storage management, and factors that can't, such as the weather.

Advice for preventing crop loss:

Select a site that's elevated, has good drainage and is large enough to accommodate the volume of crop being stored and has roughly 130 feet of turnaround space for trucks dropping off the grain.
Prepare a pad for the grain to rest on by mixing lime, fly ash or cement in the soil to prevent soil moisture from wetting the grain. Make a concrete or asphalt pad if the site will be used for several years.
Create a crown in the middle of the pad with a gradual slope away from the center for water drainage. Also make sure the area around the pad drains well.
Run piles north and south to allow the sun to dry the sloping sides.
Build a retaining wall to increase storage capacity.
Place only cool (less than 60 F), dry, clean grain on the ground. Maximize pile size to reduce the ratio of grain on the surface, which is exposed to potential weather damage, to the total grain volume.
Build the pile uniformly for maximum grain surface slope and avoid creating hills, valleys, folds and crevices that will collect water.
Form the pile quickly and cover it immediately to minimize its exposure to moisture, wind and birds.
Install an aeration system to cool the grain so its temperature is uniform and equal to the average outdoor temperature. Cool temperatures minimize mold growth, limit moisture movement and control insects.
Check grain temperatures and moisture content at several locations in the pile every two to three weeks.
Frequently check the pile's cover for rodent-caused perforations, damage from wind or ice, worn spots and vandalism, and make repairs.
Inspect retaining walls for separation or movement at the connections and deterioration of the materials in the walls. Also make sure wall anchors still are holding.
When removing the grain, load it from the center of the pile to prevent uneven pressure on the retaining wall.
Try to separate spoiled grain from the pile to limit the amount of grain that needs cleaning, drying and blending with other grain stored in outdoor piles.

Producers also have alternatives to piling grain on the ground, such as storing grain in empty barns and pole buildings used for machinery storage. Here are some tips when using these buildings:

Make sure the site is well-drained.
Strengthen buildings to support the pressure of the stored grain. Most buildings were not designed or built to withstand any pressure on the walls.
Check with the building's manufacturer on how deep to fill the structure with grain.

Special Grades of Corn:

Flint
Flint and dent
Weevily
Waxy

Corn is traded on the basis of US No. 2

No premiums for US No. 1
Docked if below US No. 2

CORN GRADING: Grade Requirements for Corn

		Maximum limit of damaged kernels
Grade	Minimum test weight per bushel	Total damaged kernels	Heat damaged kernels	Broken corn and foreign materials
	pounds	percent	percent	percent

U.S. Number 1	56.0	3.0	0.1	2.0
U.S. Number 2	54.0	5.0	0.2	3.0
U.S. Number 3	52.0	7.0	0.5	4.0
U.S. Number 4	49.0	10.0	1.0	5.0
U.S. Number 5	46.0	15.0	3.0	7.0
U.S. sample grade U.S. sample grade shall be corn which: Does not meet the requirements for the grades U.S. Numbers 1, 2, 3, 4, or 5; or In a 1,000 gram sample, contain 8 or more stones which have an aggregated weight in excess of 0.20 percent of the sample weight, 2 or more pieces of glass, 3 or more crotalaria seeds (Crotalaria ssp.), 2 or more castor beans (Ricinus communis), 8 or more cockleburs, 4 or more particles of an unknown foreign substance(s), or a commonly recognized harmful or toxic substance(s), or animal filth in excess of 0.20 percent; or has a musty, sour, or commercially objectionable foreign odor; or is heating or otherwise of distinctly low quality.

Storage

EAR CORN STORAGE - CORN CRIBS