Craige Mackenzie, Canterbury
Mid-Canterbury arable and dairy farmer Craige Mackenzie's philosophy is right input, right quantity, right place, right time—which makes sense for his business and for the land, waterways and climate. Conditions often aren't in his favour, but precision technology is helping to even the odds.
About the farm
Craige and Roz Mackenzie farm Greenvale Pastures on the Canterbury Plains near Methven.
Greenvale is a 200-hectare intensive, irrigated cropping farm growing high value seed crops (including wheat, fescue, ryegrass, hybrid carrots, pak choi, radish and chicory) and cereals – with an enduring emphasis on environmentally sustainable farming practices.
SIDE NOTE: 65% of the world’s carrot seed is grown in the Canterbury area, and 35% of the world’s radish seed.
The farm’s location, one-third of the way between the mountains and the sea, makes for some interesting climatic challenges with both alpine and coastal effects during the year.
On average, Greenvale gets 900 mm rainfall per year on a 50-year average, although in 2021 it received 1670 mm. However, the water-holding capacity in the different soil types on the property ranges from 60mm to 200mm in the top 60cm. In addition, the farm can get significant west to nor-west winds, although this is contrasted with the ability to receive up to a metre of snow during some winters.
To help combat the climatic challenges and stabilise production conditions for their crops, irrigation was introduced to the farm in the 1980s. Craige has since pioneered a precision irrigation system that has seen the property divided into 35 individually managed zones. Soil variability is mapped via electromagnetic sensors and the soil survey data determines where soil moisture probes are placed in each zone. These then feed information back to Craige’s laptop in real time along with rainfall and evapotranspiration data to work out where water is and, importantly, isn’t needed. He consults high-resolution weather forecasts to see if nature is likely to deliver that water or if irrigation is needed.
Through the soil mapping and testing process, Craige also discovered that potential yields varied significantly across the farm. He realised that he was overdoing the inputs in some areas, which wasn’t good for his bottom line or the environment. Now, data from soil maps, spatial soil sampling, yield analyses and nitrogen scanners help him calculate exactly how much fertiliser is required.
GPS-driven variable rate irrigators, sprayers and fertiliser applicators are then put to work, delivering precise doses of water and fertiliser in exact locations across the farm.
Craige also uses this wealth of data to carefully plan his crop rotations, avoiding the need for cover crops and ensuring no land is left fallow. This helps further reduce the amount of nitrogen used, along with other inputs. It also staggers how much water might be required for any given crop and helps improve soil quality and health.
For Craige, while the upfront investment wasn’t cheap, he’s seeing returns within 12-24 months and the longer-term payoffs have been significant too.
Environmental focus
The benefits of Craige’s precision agriculture approach are not just evident in his increased production and productivity – the environment has been a winner too. Since 2016, the Mackenzies have reduced their water use by 30-40% and their fertiliser use by 30%.
These efforts have been underpinned by a farm environment plan, required as part of the Ashburton-Lyndhurst Irrigation Scheme that Craige is a member of.
His system is now capable of ensuring that water does not go past the root zone, significantly limiting nitrate and phosphate leaching.
“For us, it’s about using our resources as wisely as we can and having the lightest footprint possible on the environment,” says Craige. “We believe in protecting and carefully managing this land for future generations.”
But just what impact have Craige’s actions had on the climate?
Craige's greenhouse gas numbers
Craige’s use of precision agriculture means he is already able to capture an array of data for his farm. Getting his greenhouse gas numbers together was relatively straightforward – completed via Overseer.
Overseer is just one of a number of tools available for farmers to find out their greenhouse gas numbers. You can read more about them on our Know Your Numbers page.
Greenvale Pastures | 2019 | 2020 | % change |
Effective area (ha) | 197.4 | 197.4 | 0 |
Total methane (tonnes CO2e/ha) | 1,080 | 1,044 | -3.3% |
Total nitrous oxide (tonnes CO2e/ha) | 2,149 | 1,912 | -11% |
Total carbon dioxide from nitrogen fertiliser (kg/ha) | 994 | 1,011 | 1.7% |
Total biological GHG emissions (tonnes CO2e/ha) | 4.2 | 4.0 | -6.1% |
N surplus | 185 | 152 | -17.8% |
Methane (kg/ha) | 43.2 | 41.8 | -3.3% |
Year on year, precision agriculture enables Craige to continue making efficiency gains and reducing key inputs like nitrogen fertiliser. In turn, this has a positive effect for the climate with 11% less nitrous oxide emissions between 2019 and 2020 and nearly 18% less nitrogen surplus.
On-farm actions
Craige’s dual focus on innovation and sustainability has led to positive outcomes for the climate. The main way he has reduced his emissions is by managing his nitrogen use via precision agriculture:
- Matching inputs to crop requirements
- Variable rate application
- Using urease inhibitors
- Soil mapping and regular testing
- Crop rotation
- GPS mapping
- Using crop sensors and satellite imagery
For more on this and other ways to reduce agricultural greenhouse gas emissions, see our Current Actions page.
Know your numbers and have a plan
By now, all farmers and growers must have a record of their annual on-farm greenhouse gas emissions (methane and nitrous oxide). By the end of 2024, they'll also need to have a written plan in place to manage them. These requirements are part of the He Waka Eke Noa partnership and are intended to help get farmers ready for agricultural greenhouse gas emissions to be priced from 2025. To find out more on how to do this, see our Know Your Numbers page.