State-of-the-art systems change farm irrigation
Dave Harwood inspects the intake pond for their irrigation system. Photo: Gerard Hindmarsh.
If you’ve driven up the Cobb Road from Upper Takaka lately, you couldn’t help but notice them, seven big centre-pivot irrigators on the lush farmland around the Waitui Stream and Takaka River.
The first two appeared in 2008, but this season they were joined by five more, the longest nearly half a kilometre long. The self-driven irrigators, which are complemented by K-line sprinklers, represent a significant investment by the Harwood family, to not only raise production on their 265ha dairy unit, but keep it stable during dry periods.
“Dry spells have always been the biggest holdup to farming up here,” Nigel Harwood explains. “Often in the spring, we get 10 days of wind and the land goes from useless because it’s so wet, to useless because it’s so dry. This irrigation system aims to future-proof us against those significant dry periods.”
Without a doubt, the application of state-of-the-art irrigation technology is intended to increase output. To date, the Harwoods have been producing around 800 kg of milk solids per hectare (off dry land dairy country). Now they expect their pivot-irrigated areas to produce over 1400. Some irrigated dairy farms on prime Canterbury pasture are known to produce over 1600.
Nigel acknowledges that some people have issues with big irrigators on the rural landscape, but believes this should all be weighed against gains in farm efficiency. He points out pivots are a highly effective way to apply water, and “future technology” further improves their efficiency. One of their pivots is equipped with technology that allows different water rates to be applied according to soil types.
Nigel also likes to point out that their impact has been minimal. “Sure, we had to level off a few bumps and hollows to make way for the path of the pivot towers and we have removed a few trees, but these consisted mainly of some old man pines and gum trees we planted for stock shade and firewood.” Because of the terrain and transmission lines from the Cobb that run through the farm, all but one of the pivots had to be designed to do half circles.
A tour of the Harwood farm reveals just how big this job has been for the family. A clay-lined intake pond of swimming-pool proportions had to be built alongside the upper reaches of the Waitui Stream. From here a 400mm buried PVC pipe now runs downhill and delivers the water 1.7km to the double-pump shed, which then supplies the pivots and K-Line. The fencing required for the changeover to pivots has been massive, with new layouts and specially positioned gates required for the wheels to pass through. Everything is designed to work like clockwork, with software to squirt a jet here or there, or just shut the irrigators off as they go around roads, power lines and buildings. If there’s a glitch, managers’ cellphones ring automatically.
Getting all the permissions required to install these contraptions was a small feat in itself, the design of the scheme also having to focus on environmental mitigations. Planned in conjunction with this project will be the building of a mini-hydro electric plant to generate electricity during the winter months when the irrigation scheme is not in use. Fish and Game provided information and support throughout the application, and will design the tail race for the mini hydro plant so that the Waitui Stream functions as a fish-spawning stream. The scheme will also “liven” a significant lower stretch of the Waitui that is currently dry for most of the year. The irrigation scheme’s licence to take is restricted to 90 litres a second, and this is required to be cut off when the stream drops to 200 litres a second.
Although centre pivots may be relatively new to the Bay, the Harwoods simply joined a growing list of Golden Bay agricultural irrigators. In the Takaka Valley, there are already several farms that routinely irrigate, mainly with K-line systems. These conspicuous, black, oversized garden sprinklers (usually connected in groups of six to eight) are typically towed to a new position each day with a farm bike. Several dairy farmers up the Aorere also extract water for use with K-line irrigators. These are less costly to install, but require daily shifting so are labour-intensive.
Water availability in the Takaka Valley has become an issue. Dave Harwood admits it was getting more and more difficult to get permission to take water out of the Takaka River.
“Irrigators in the Takaka Valley are reliant on the Cobb Dam generating to get water in the height of summer. This is the reason we went for the Waitui, so as to provide a more stable supply in the summer months.”
The Harwood family has farmed in Golden Bay for a long time, since Nigel’s great-grandfather came as a lighthouse keeper to Farewell Spit in 1888, and ended up buying the original Rat Trap Hotel with 400 ha of land. This land holding has since expanded to 2500 hectares and extends to operations in deer, sheep, cattle, forestry and dairy. Diversification comes naturally to this family. Nigel’s brother Simon runs the family’s sharemilking operation in Chile, Dave Harwood looks after their 760ha lamb-finishing farm at Turimawiwi, and Jon Harwood runs the drystock operation at Upper Takaka.
Gerard Hindmarsh
