Determining the Optimal Time to Chop Corn Silage

Harvesting silage at the right moisture content is essential for achieving optimal quality and efficient storage. One of the challenges growers face is knowing when silage is ready for chopping. The dry matter content of the whole plant can vary with maturity, making it crucial to accurately assess the plant’s moisture levels before harvest. Here’s how to navigate this process.

Silage Chopping Moisture: Key Considerations

Harvest timing can often be estimated using the kernel milk-line, which is a good initial indicator for when to start sampling fields for plant dry matter. However, the only truly reliable method for determining the optimal harvest time is to sample the crop and measure the percent dry matter of the entire plant. Below are the methods to help with this determination:

• Kernel Milk-Line
• Whole-Plant Moisture Testing
  • Microwave Method
  • Koster Tester

1. Kernel Milk-Line

The kernel milk-line is the line in the kernel separating the liquid (milk) and solid (doughy) portions of the kernel. This can serve as a rough estimate for harvest timing. To check, break a cob in half and examine the kernels on the tip half of the ear. As the corn matures, the milk-line will move from the outer edge of the kernel toward the cob. Typically, harvest should begin when the milk-line reaches the halfway point, where half of the kernel is milky and the other half is doughy. Keep in mind, the milk-line provides only a rough estimate and should not be used as the sole indicator for determining silage moisture content.

2. Microwave Oven Dry-Down Test

The microwave dry-down test is a reliable and quick method to assess moisture content. Follow these steps:

1. Weigh a 100-gram sample of chopped silage on a paper plate (do not include the weight of the plate).
2. Spread the silage evenly over the plate and place it in the microwave. To prevent ignition, add an 8-ounce glass three-quarters full of water in the back corner of the microwave.
3. Heat the sample on high power for 3 minutes.
4. Remove the sample, weigh, and record the weight.
5. Stir the sample and return it to the microwave. Continue heating in 1-minute intervals, stirring between each cycle. As the sample approaches dryness, switch to 30-second intervals to prevent burning.
6. Continue drying and weighing until the total weight changes by less than 1 gram.
7. The final dry weight, minus the weight of the plate, gives you the dry matter percentage. To calculate the moisture content, subtract the dry weight from 100.
8. Repeat the process with a duplicate sample and average the results.

3. Koster Tester

The Koster Forage Moisture Tester is another tool to measure moisture content. It works similarly to an oven by drying the forage sample and determining moisture content based on the weight change. This method is often used for more precise moisture analysis.

Summary: Understanding the Moisture Content

Accurately determining corn silage moisture content is a challenging but critical process for ensuring the best silage quality. Once you've completed your moisture testing, you'll be closer to knowing the optimal time to begin chopping. To predict when your field will be ready for storage, apply a dry-down rate of 0.5% per day, this is the average moisture loss of corn plants as they mature. By understanding and applying these methods, you can avoid harvesting too early or too late which can impact the quality of your silage.