Variations in corn fields adds variability to silage plans
Having a good plan for silage in place prior to harvesting will prevent problems with storage.
Corn planted this spring has had the benefit this summer of some heat that puts our growing degree days near normal for the year. But, it doesn’t mean we’ll see corn at the same stage of development as corn planted under normal conditions. If we add in the factor that many fields were planted in June, it gives us even more variability. Much of the early planted corn may have had uneven emergence or portions of the field replanted due to early flooding. What should a producer do in these situations? It’s important for producers to know what the whole plant moisture content will be as they head to the field. Tasseling is a good indication of how much delay you will have in your corn fields.
For proper corn silage storage, farmers should harvest corn on a dry matter basis. The optimal dry matter content for bunker silos is 33 to 35 percent; for ag bags 33 to 37 percent; for upright silos 35 to 38 percent; and for oxygen limiting silos 40 to 45 percent. Whole plant moisture contents will dry down approximately 0.5 to 0.6 percent per day.
The University of Wisconsin suggests that the best way to harvest a field with a large problem area depends upon row orientation. If an uneven area is located in a field so that each pass of the chopper moves through the area, then enough mixing will occur that fermentation will proceed in the silo without problems. However, if the area is orientated to the rows so that the chopper will not move through the area with each pass, then the area should be segregated and harvested separately.
Producers need to guard against forming layers in the silo that are significantly wetter or drier than the optimum moisture for the storage structure. This would typically be seen with large problem areas in a field or when switching to fields that differ significantly in moisture.
The biggest concern for corn silage is the potential for mold development when plants are too dry. Mold increases the chance of mycotoxin development in the silage. For corn that is too wet, a bunker silo might be the best storage structure to use. Immature areas within a field will be wetter than the rest of the field and might seep in the bunker, but as long as the seepage does not leave the bunker, nothing is lost. For these reasons, farmers may want to pick more uniform fields to ensile.
To measure whole plant moisture, some producers may not take the time needed to do a good job. It’s not as simple as it sounds. I encourage producers to harvest representative stalks at the height of their chopper cut. A fine chop (maybe through a mower) will provide more accurate moisture content. Then, use a Koster Tester or microwave to measure moistures. Just a word to the wise, if farmers want to keep peace in the household, I don’t recommend using the kitchen oven or the family microwave. These methods each have a degree of variability, so make sure the same protocol is used when evaluating the results.