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Virginia Cooperative Extension -
 Knowledge for the CommonWealth

To Minimize Silage Seepage,
Harvest Silage Crops for 35-40% Dry Matter

Dairy Pipeline: May 2000

Gerald M. (Jerry) Jones
Extension Dairy Scientist, Milk Quality and Milking Management
Virginia Tech
(540) 231-4764

There is increasing environmental concern over silage effluents or leachate. The high oxygen demand and low pH can upset the balance of life in waters receiving silage effluent. Ensiling forage at higher moisture increases the likelihood and amount of silage effluent. Forage for silage should be harvested at 65% moisture or less (35% dry matter or higher) to minimize risk of seepage. And besides, silage with 70% moisture is usually of poor quality. Wet haycrop and small grain silages are prone to clostridial fermentation resulting in high levels of butyric acid and break down of protein to ammonia, causing a strong odor. Corn silage at 70% moisture can be acidic and intake depressed. Ground hay or corn can be added to wet forage at ensiling to increase dry matter content. At the other end, moisture contents below 50% (over 50% dry matter) cause heat damage, which also destroys part of the protein, and promotes molding. Drier silages are difficult to pack and exclude air. Dry matter content can be higher in oxygen-limiting silos. Silage effluent can be collected and handled with milking center wastewater, exercise lot runoff water, or in a liquid manure system. If seepage is a problem, channel the liquid into a water retention structure, usually a pond lined with concrete, clay or plastic. The effluent contains nitrogen and organic acids that could burn plant tissue; the liquid should be land applied during the growing season. However, mixing silage effluent and liquid manure increases the production of deadly hydrogen sulfide in pump pits and tanks. Therefore, use extreme caution when agitating and pumping stored silage effluent. Do not enter collection sumps or underground tanks that are part of the silage effluent handling system. Silos should be located away from wells and springs. Where the risk of effluent is low, silos should be at least 100 ft. from wells and 250 ft. from earthen pits.

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