When applied to ponds at equivalent rates, liquid fertilizer was much more effective than granular triple superphosphate in increasing futrable orthophate concentrations. Four methods of applying liquid fertilizers were tested: (1) liquid fertilizer was introduced into the intake side of a pump, mixed with water, and discharged into ponds, (2) a power sprayer was employed to spray the fertilizer over portions of pond surfaces, (3) a compression-type hand sprayer was used to spray fertilizer along shallow water edges of ponds, and (4) fertilizer was drained into the propeller wash of an outboard motor as the boat was driven back and forth over pond surfaces. All 4 methods proved effective. For 20 tests (5 for each method), filtrable orthophosphate concentrations averaged 0.02 mg/l before application and 0.29 mg/l 24-hr after treatment.
