With harvest wrapped up and your grain nicely stored away in the bins, its high time we had a talk about some best management practices for keeping your stored grain in tip top condition. We’ve lined up the top 5 things you need to know to keep your grain in a stable position, reduce spoilage, and eliminate insect activity.
1. Storage for High Moisture Grain
With a cool, wet fall, or possibly an early freeze on corn that didn’t make it to black layer, there is a good possibility that you are dealing with some above average moisture corn. This adds a little complexity to our drying systems. First of all, if you didn’t get your corn moisture down to 15%, then it is really important to get the temps down to 25-30 degrees. This will slow any fungal growth than can occur with wet corn. In fact, if your grain is above 18% and more than 50 degrees, sources suggest running the fan near constantly to reduce the moisture (if possible) and get the temp lower as soon as possible.
Spoilage and grain bridging are way more likely when we put wet corn in the bin and try to dry without forced air. Be very careful when unloading bins and use a safety harness if you have to get inside.
2. Shelf Life Expectations
If we can get our grain temperatures down to 20-30 degrees and moisture down to 15%, we are going to have a much longer shelf life for our grain. Any temp below 50 degrees will keep insects dormant. Even colder temperatures will slow fungal growth.
If you are planning on storing for less than 6 months, 15% moisture should be adequate. If you are planning on storing corn longer than 6 months, 13% moisture is recommended. This chart from Iowa State gives some guidelines for how long you can expect to keep grain stored at different temperatures and moisture contents.
UNL gives two rules of thumb regarding shelf life:
· “When the corn is above 16% moisture, the shelf life is half as long at a given temperature for every two percentage points higher moisture content.
· At a given moisture content, the shelf life is half as long for every 10°F increase in temperature. Grain above 16% moisture in a bin will deteriorate about three times as fast as the estimates in the table if it is not aerated to carry away the heat generated by the fungal growth.”
3. When/How to Cool
Our goal with drying grain for long term storage is to get it cold and to decrease the moisture content to a stable level. Simple enough right? One of the easiest ways to do this is to consult an equilibrium table. Based on the temperature and relative humidity outside, we can determine what the grain moisture would even out as. For instance, if the air temperature was 35 degrees, and the relative humidity in the air was 40%, given enough time, the grain moisture would eventually settle at 11.8% moisture. If you have a moderate temperature day that indicates the equilibrium moisture is a few points dryer than what the wettest grain in your bin is, run the fan to get some drying done. Just remember if you warm up the grain too much trying to dry, make sure you run the fan during some cold weather to cool your grain temps back down to below 30 degrees.
It’s also important to run the fan long enough to push the current environmental conditions through the whole bin. If you stop after only a couple hours, you will create a temperature and humidity differential inside the bin which can be detrimental to grain quality. The rule for pushing a cooling front through the bin is to divide 15 by the cfm/bu of your system. For example, if your system is 1 cfm/bu, it would take 15 hours to move that air through the whole bin. If it were a 0.3 cfm/bu system, it would take 50 hours to get the air through the bin.
4. Maintenance Practices
Some other general practices include doing a sniff test. Turn your fan on for a few minutes and then go open the top hatch and smell. Does it have an off odor? Chances are there could be some spoilage. Run the fan to see if you can bring the whole bin to an equilibrium, run your stirator if you have one, or if the problem persists, unload the bin until the level of damaged grain is removed.
Keep good track of your temperature distribution. If you have a permanent system in place, check for temperature variation at depths and across the bin. If there is more than a 5-8 degree temperature difference in the bin, run the fan to even the temperature out.
Take some extra time to level your bin after filling. If you pile your grain as a peak, it takes 50% more fan time to cool vs a level grain bin. Energy savings could be significant, not to mention the decrease in time to bring grain to a stable state.
5. Safety Procedures
Each year we hear of more tragedies regarding grain bin accidents. USE CAUTION and many of these can be avoided.
· If you suspect there is crusting and bridging going on in the bin, break it up by using a long pole from the outside of the bin.
· If you feel grain start to move beneath you, get to the outside wall of the bin immediately. Keep walking along the edge until the grain movement stops and you can get safely out.
· Invest in, and use a safety harness attached securely by rope. Always have someone else standing by outside bin for safety—preferably two people.
· If unloading equipment is running---stay out! Before you climb in, disable auger mechanisms by locking out the circuit so someone cannot accidentally turn on the unload auger while you are inside.
· If someone else becomes submerged in grain, call for help immediately. DO NOT ENTER THE BIN. Your next step is to then cut holes in the side of the bin, about 5 feet off the ground so grain can exit. Cutting too many can cause the bin to collapse, so spread out the holes around the bin. Use a loader on a tractor or an air chisel or saw, but NOT a torch as that can cause a fire with all the fines, dust, and other combustible material in a bin. Turn on the fan to push air through to the trapped individual.
I know some of these things seem like a hassle to take time to do---but your life is worth it. Stay safe out there.
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