Think Pink- For a Healthy Lagoon

By Eve H. Honeycutt

Extension Livestock Agent, Lenoir and Greene Counties

Even though we are in the dead of winter, it is never too late to think about maintaining a healthy lagoon.  It will be spring before you know it and many of you will be ready to use some of those stored nutrients.   While you are planning for the spring, plan for your lagoon too.

First a few words about the life cycle of a lagoon.  As solids build up in your lagoon, anaerobic bacteria also builds up.  These bacteria do not need oxygen to survive, so please don’t ever let anyone talk you into aerating your lagoon.  As these aerobic bacteria multiply, they “breathe” and release carbon dioxide, which we see as tiny bubbles on the surface of the lagoon.   Soon after the bubbling begins, the purple sulfur bacteria come to life.  These purple sulfur bacteria are named that because of the characteristic purple color they release as part of their digestion and the sulfur gases that give the lagoon it’s unique smell.  Once these guys are on the scene, you can bet your lagoon is working hard to digest the solids at the bottom.   This bacterial activity is 3-4 times greater in the summer, which is why most lagoons don’t turn pink until the weather warms up.

The key now is to maintain the anaerobic party going on and keep your lagoon from building up solids too quickly.  However the tricky part is keeping all of them “happy”.  Your bacteria can become “unhappy” and die off for many reasons.  Washing down the house with a disinfectant, overloading the lagoon with liquids or solids, heavy rain, and extreme temperatures can all affect the pH balance in your lagoon.  Collecting accurate and reliable waste samples is a great way to monitor your lagoon- especially the pH.  A good pH for a lagoon is about 7.5.  If the pH is too low, you can bring it up by adding lime at a rate of 1 pound per cubic foot of liquid.

If you find yourself with a lagoon that is collecting a lot of solids, black in color, or low bubble activity, you should take some action to improve it.  Lack of good management on your part can result in an expensive lagoon cleanout sooner than you may be ready for.  One good management tool is an agitator.  Using an agitator regularly, especially in the summer, can suspend the solids in the lagoon and allow for increased bacterial activity.  I have seen this method work very well for lagoons on more than one occasion.  If you are going to use an agitator, remember to sample the water AFTER you agitate since you will be releasing more nitrogen and phosphorus with the movement.  You also want to let the solids settle down a bit before  you pump so you don’t wear out your equipment. 

A little management and planning can go a long way.  Contact your local Extension office if you have any other questions.  Lagoons are a vital part of a hog operation, and they demand your attention.  Think Pink!