Costs and benefits of in-house compost production of 20 Megagrams (Mg)/yr for four 4-ha vineyards. VM, vineyard manager; CAPEX, initial capital expenditures.
| Category | Cost ($) | Benefit ($) | Year of occurrence | Description | Source |
|---|---|---|---|---|---|
| Initial costs | |||||
| Turner | 8000 | - | 1 | Main equipment required to mix the composting materials. Assuming secondhand equipment. | VM |
| Utility tractor - front loader | 5000 | - | 1 | This assumed tractor from vineyard can be used; only front loader implement would be required. | VM |
| Thermometers | 400 | - | 1 | Four units. Temperature monitoring. | VM |
| Plastic | 80 | - | Every 3 yr | Compost pile cover, periodic replacement. | VM |
| Total initial costs | 13,480 | - | 1 | ||
| Annual operating costs | |||||
| Labor | 1680 | - | 3 to 30 | Management and maintenance of compost (e.g., monitoring, turning, mixing, and adding water): 4 hr once per week for 5 to 6 mo. | VM |
| Resourcesa | 140 | - | 3 to 30 | Mainly water and chicken manure. Additional organic matter if required. | VM |
| Equipment maintenance | 60 | - | 3 to 30 | Tools and machinery. | VM |
| Total annual operating costs | 1880 | - | 3 to 30 | ||
| Annual benefits | |||||
| Waste management | - | 1344 | 3 to 30 | Savings on waste fee disposal from Zero Waste Sonoma (e.g., yard debris): $112/Mg, and assuming 30% biomass discarded from winegrape. | Zero Waste 2024b |
| Total annual benefits | - | 1344 | 3 to 30 | ||
| Net annual cash flow | - | - | - | $1344 - $1880 = -$536/year (Non-CAPEX years) | |
↵aScreening to finish size (to achieve homogeneity in compost) was not considered, which can increase cost by up to 40%.
↵bhttps://zerowastesonoma.gov/disposal-options/central-disposal-site-transfer-stations-fee-schedule.