Likewise, spreading manure on frozen soil could pollute surface water if it rains or snows while the ground is still frozen. Slurry waste systems require more land for application than lagoon systems because more nitrogen is retained. Most lagoon effluent is more than 99 percent water, so it has the consistency of water. Flushing is the preferred method of manure collection and transportation for many Missouri dairies because it eliminates the labor required for scraping and moving waste to storage. Lagoons complement flushing systems because they provide storage at relatively low cost and usually do not cause unacceptable odor problems if judiciously located.
Lagoons can also provide a source of flush water.
The anaerobic breakdown of waste usually results in acceptable odor levels when applied by an irrigation system. Approximately 90 percent of the input nitrogen is lost in a lagoon, but this can be an advantage if limited land is available for waste disposal. Lagoons are usually designed for a 365-day storage capacity with all waste going into the lagoon. This includes dry cow waste, but not calf and replacement heifer waste. Also note that lagoons are not allowed by DNR in areas where soil collapse potential is high.