Fertilization calculator

These are per-acre rates from the extension tables, scaled to your pond. They assume a bass and bluegill pond at least three feet deep over most of its area. Decide on each application from the visibility reading, whatever the calendar says.

Start when the water stays above 60 F in spring. Make three applications two weeks apart to start the bloom, then apply again whenever a Secchi disk or a white object on your arm disappears deeper than 24 inches. Skip an application when visibility is under 12 inches, because that bloom is dense enough to crash and pull oxygen down overnight. Check oxygen at dawn while it stays that dense. Between 12 and 24 inches the bloom is where you want it, so wait a week and read it again. Stop when the water cools in fall. A typical season runs 8 to 12 applications.

Do not fertilize when total alkalinity is under 20 ppm. Lime first (the liming calculator), because phosphorus is tied up in soft water and the bloom will not come. Do not fertilize a muddy pond (plankton needs light), a pond with rooted weeds or filamentous algae over much of it (the weeds take the nutrients), a pond that is rarely fished (more fish only means more to manage), a pond with steady outflow (the fertilizer leaves), or a pond used for swimming or as a drinking source.

The rates and schedule come from Mississippi State Extension publication p1428, Managing Mississippi Ponds and Small Lakes, and SRAC 471, Fertilization of Fish Ponds. Practitioner discussion: Pond Boss forum threads Fertilization of ponds and Triple Super Phosphate.