Economic evaluation of transplant robots for plant cuttings

Abstract

Abstract Transplanting of unrooted plant cuttings to produce rooted liner trays is a manufacturing process that requires considerable manual labor. However, increasing labor cost and reduced labor availability has increased interest in automation. The objective was to evaluate return on investment of transplanting robots, and identify key factors that businesses should consider when purchasing a transplanting robot. Data on labor costs, cuttings transplanted, and costs of automated transplanting were surveyed at six greenhouse firms. The resulting average scenario assumed an annual labor cost of $408,377 to manually transplant 29.3 million (M) cuttings at $12.49 per hour, resulting in a cost of $0.014 per cutting. An investment of $125,000 in one transplant robot operated for up to 76\u2009h per week (2 shifts) had an annualized cost of $70,270 ($6,250 cost of ownership and $64,020 labor cost for robot operators). The robot could transplant 7.2\u2009M cuttings per year (25% of the total), at an average cost of $0.010 per cutting compared with $0.014 for manual transplanting. With these assumptions, over 10 years the transplant robot would yield an annual cash flow saving of $29,891 a Net Present Value (NPV) of $105,807 and a discounted payback period of 4.8 years. Each transplant robot would reduce labor requirements during the peak week by two full time equivalent workers (3% of total workforce). Sensitivity analysis showed investment in automatic transplanting was increasingly profitable with a high local wage, and low manual labor efficiency (few cuttings per workers). There were economies of scale when more than one robot was used. Greater efficiency resulted from increasing hours of robot operation during the peak period, and in operations where cuttings were transplanted throughout the year. Results can be used to evaluate the impact of automation on labor cost and availability for the transplant process.