Assessments of plastic waste in the agricultural industry have been performed by GHD for the Environment Canterbury Regional Council in 2013 and the Waikato and Bay of Plenty Regional Councils in 2014. Council waste assessments also include some farm waste data but are not included in this case study. These three regions have the highest number of farms in Aotearoa New Zealand. The same survey methodology was used across both studies, but the breakdown of waste type differed, limiting comparison of specific materials across both. There were 53 farms surveyed for Canterbury and 69 for the Waikato and Bay of Plenty. Non-natural rural waste includes waste streams from dairy, livestock, arable farming and horticulture. Key findings:
- National projections based on these assessments estimate over 2.1 million tonnes of rural wastes (including plastics) are produced annually in Aotearoa New Zealand (37 tonne average per property multiplied by 58,071 rural properties in New Zealand, not accounting for variations in activity by different farm type)
- Plastic was one of the most prevalent non-natural rural wastes. Types of plastic waste are varied and some are hazardous. Examples include containers, drums, silage and baleage wrap, netting, mulch film and crop cover, agrichemical containers, animal health plastic packaging and plastic sheep dip, fertiliser bags, domestic refuse (see Appendix 12)
- Almost all sites burn, bury and/or bulk store waste indefinitely as a disposal strategy (92% Canterbury; 100% Waikato and Bay of Plenty), which has the potential to impact water quality in streams, rivers and groundwater, and air quality
- Significant differences in plastic use may result from different farming infrastructure – for example, areas where farms had irrigated paddocks there was a reduced volume of plastics from wraps and sacks.
Example waste streams of plastic from rural properties
| Waste type | Canterbury | Waikato/Bay of Plenty | ||||
|---|---|---|---|---|---|---|
| Total surveyed (tonnes) | Average/farm (tonnes) | Total for 8826 farms x average | Total surveyed (tonnes) | Average/farm (tonnes) | Total for 14,685 farms x average (tonnes) | |
| Containers | 1.7 | 0.03 | 264.78 | 2.2 | 0.03 | 440.6 |
| Drums | 2.7 | 0.05 | 441.3 | 5.0 | 0.07 | 1027.9 |
| Silage wrap | 14.8 | 0.3 | 2647.8 | 11.4 | 0.2 | 2937.0 |
| Netting | 10.9 | 0.2 | 1765.2 | 9.1 | 0.1 | 1468.5 |
| Mulch film and crop cover | 2.6 | 0.05 | 441.3 | 5.8 | 0.1 | 1468.5 |
These studies estimate that these three regions generate over 700 tonnes of plastic containers per year, which is over half the weight of the 1200 tonnes of 0-60 litre containers estimated by Agrecovery for 2018.
While these findings need to be verified by further studies, they do indicate that there is a significant amount of plastic waste from agricultural settings and highlight the need to ensure the agricultural sector is considered when rethinking plastics in Aotearoa New Zealand.