Supercow

Small‐plot research in manure nutrient management requires accurate manure applicators that are easy to operate and maneuver. Our objective was to design a small‐plot liquid manure applicator that could apply variable rates of dairy manure containing up to 60 g kg −1 solids to perennial grass plots while avoiding traffic and compaction on the plots. The applicator consists of a 1000‐L fiberglass agitation tank mounted on four load cells, a delivery pump and motor, and a side‐mounted boom with four nozzles for manure application, all built onto a wagon and towed by a tractor. The side‐mounted boom allows manure application without traffic on the plots. Manure application typically was within 7% of the target rate and had a coefficient of variation ranging from 2 to 17%, measured over a series of rates from 53 to 211 Mg ha −1 (wet weight). The precision, accuracy, and ease of operation of the applicator met our research requirements. Efficiency of operation could be improved using a larger agitation tank.