Development of an automated application system to apply copper sulfate pentahydrate to commercial catfish ponds using precision dry fertilizer application technology

Deleterious trematode infestations in U.S. farm-raised catfish have led to significant investment to develop safe and effective measures to disrupt trematode life cycles by targeting the snail intermediate hosts. Copper sulfate pentahydrate (CSP) is widely used in catfish aquaculture due to its phytotoxic, parasiticidal, and molluscicidal properties. Traditional methods of CSP application involve preparing near-saturation solutions and pumping the solution without metering across multiple ponds. At the farm level, this approach is time-consuming and can lead to inaccurate treatment rates, which sometimes reach toxic levels, posing serious risks to fish health. To address these challenges, a precision copper sulfate delivery system was developed to accurately distribute granules around the littoral zones of ponds, where snail densities are highest. To this end, a Gandy multi-purpose fertilizer applicator was modified and integrated with precision application technology to regulate granular CSP distribution rates in relation to ground speed. Performance evaluations of the CSP metering and application system were conducted under both static and dynamic conditions. Application rates were measured as a function of copper sulfate discharged from metering wheels relative to the rotational speed of the controlling driveshaft, with metering regulated by varying the voltage applied to a DC gear motor. Static and dynamic analyses were performed at simulated ground speeds between 3.2 and 8.0 kph across target dosages of 1, 2, and 3 ppm. Static evaluations demonstrated a slight under application of CSP, particularly when using small crystals at low treatment rates. Conversely, dynamic evaluations showed a slight over-application of CSP, with discharge rates exceeding target dosages. A comparative analysis against theoretical discharge rates revealed consistent performance, regardless of particle size, with deviations becoming more pronounced at higher ground speeds and application rates. Despite some observed variations between static and dynamic conditions, the system’s precision and accuracy were deemed acceptable for practical use. The system‘s adaptability and consistent performance suggest it will be a valuable tool for improving snail control in catfish aquaculture while minimizing inherent risks of CSP applications in commercial production ponds.

Applied Engineering in Agriculture, 41(5)