This year's weather has made it more difficult than usual to guess corn maturity. The corn crop got off to a strong, early start, but then the cool summer slowed development.

It is important to remember that harvesting corn silage at the proper moisture is one of the most important steps in producing quality silage.

The ideal moisture will be determined by what kind of storage structure you will use. For sealed, airtight silos, the ideal range is 60 to 65 percent; for upright silos, 63 to 68 percent; for silage bags 60 to 70 percent; and for trench silos 65 to 72 percent moisture is the desired range.

Chopping at higher moistures often causes too much acid production (which reduces palatability), DM loss and seepage. Valuable nutrients will be lost from the crop through seepage, which can also harm the environment.

Ideally, one should test moisture during harvest to stay within the optimum moisture range. If this is not practical, you can monitor moisture by the stage of crop development. There is a simple method that can be used to determine the optimum stage for harvesting your corn silage. When the kernels reach early dent state, a separation can be seen between kernel starch and milk.

Take an ear and snap it in half. You can see the firm starch deposited in the outer part of the kernel while the milk will occupy the base of the kernel. This gives the appearance of a whitish line separating the two areas.

As the kernels continue to mature, the milk line moves down the kernels. When this line reaches the midpoint, 90 percent of the kernel's dry weight has been achieved.

When the milk line reaches the base of the kernel, a black layer is formed, separating the kernel starch from the cob and the crop is mature.

When the crop reaches full dent and the milk line first appears, the crop is usually about 70 percent moisture. When the milk line reaches the midpoint, silage yields should be at their maximum and the moisture is at 65 percent. When the milk line reaches the base of the kernel, the crop moisture is usually about 60 percent.

By observing the development of the milk line, one can determine optimum harvest time. The one limitation of this method is the weather variation.

If you have experienced extremely wet or dry conditions for a few weeks before harvest, the moisture can vary by as much as 5 percent from the predictions given above. There are also wide variations in hybrids, so testing is still important.