Maintaining Lagoon Health

By: Lynn Stillwell

Extension Livestock Agent, Sampson

With only five more weeks till spring, it is time to begin planning for the growing season ahead. On your to do list of things that are broken and need fixing make sure you check your lagoon to make sure it is still working properly. A lagoons health can deteriorate very quickly if not maintained properly.

The way most lagoons work is as solids build up, anaerobic bacteria also builds up. These bacteria do not need oxygen to survive, so do not let anyone talk you into aerating your lagoon (not the same as agitating). As these anaerobic bacteria multiply, they release carbon dioxide, which shows up as tiny bubbles on the surface. Soon after the bubbling begins, purple sulfur bacteria become active. These bacteria release a purple color during digestion as well as the smell associated with lagoons. If you have both bubbles and purple/pink you know the bacteria are working hard to digest the solids at the bottom of your lagoon. This activity is greater during the summer time, explaining why some lagoons don’t turn pink till it warms up.

Once your lagoon has the right amount of biological activity you need to maintain it to prevent building up solids too quickly. Bacteria can die off for many reasons, such as: washing down your house with disinfectant, overloading the lagoon with liquids or solids, heavy rain, and extreme temperatures. These factors can all affect pH, which can reduce the bacteria activity in your lagoon. Collecting an accurate and reliable waste sample is a great way to monitor the health of your lagoon. 7.5 is a good pH for a lagoon, if it is too low (less than 6.0) you may need to add lime at a rate of 1lb per cubic foot of liquid.

If your lagoon is collecting a lot of solids quickly, is black in color, or low bubble activity you need to take action to improve it. Ignoring your lagoon or poor management can lead to having to cleanout sooner than expected. Agitating is a great management tool if your sludge levels are increasing drastically. Regularly agitating (especially in the summer) suspends the solids in your lagoon and increases biological activity. This method is proven to work really well.

If you choose to agitate remember to sample the water after you do so to check the nitrogen and phosphorus levels, as they will probably be higher. Allow the solids to settle before pumping so as to not wear out your equipment. NC Cooperative Extension does not recommend lagoon additives as part of your lagoon maintenance because they are not a reliable way to decrease sludge.

Another important aspect to maintaining a healthy lagoon is maintaining water levels in your lagoon. Constantly pumping down to the sludge deceases biological activity and causes sludge to build up faster. With a bit of proper management and planning can go a long way for your lagoon. Lagoons are like any other equipment at your farm they only work properly when taken care of and maintained. They demand your attention and without it they drain your wallet. Please contact the Cooperative Extension office if you have any questions.