Ashburton (near Methven), greenvale [at] farmside [dot] co [dot] nz
Craige and Roz farm 200 ha in a rotation of one third wheat, one third vegetable seeds (carrots, red beet, parsley, radish, onion, hemp) and one third ryegrass for seed which is also utilised for dairy grazing throughout the winter and lamb fattening. With an equity partner they also farm an adjoining 220 ha of dairy, with 800 cows.
The farm is overlooked by Mt Hutt and Mt Somers, which were a stunning sight in full sun and covered with snow.
The essence of Craige's approach is detailed monitoring and observation leading to precision application of water, nutrients and pesticides allowing much lower applications of these, which is good for the bottom line and for the environment.
Last year Craige was a Nuffield scholar and researched carbon footprinting of different farming systems. His report to the New Zealand Nuffield Farming Scholarship Trust is at www.nuffield.org.nz. There isn't yet a system he considers satisfactory for footprinting a New Zealand arable farm but in time this should be possible.
Hemp seed is crushed for oil at the plant in Ashburton. The permit system to ensure the strain is low THC is very onerous, and an inexplicable rule that no seed may be ground for flour halves the potential income from the crop. Hemp flour is a high quality gluten free flour that would help people who cannot tolerate wheat, and it seems bizarre that when the plant has already been tested and found to comply, the seed cannot be used to best advantage.
Last November patient work with 31 neighbouring farms came to fruition with the turning on of Ashburton Lyndhurst Irrigation Ltd. This has replaced border dyke irrigation systems with an underground piped and overhead centre pivot irrigation system which takes the same amount of water from the Rangitata Diversion Race (5 km from the Mackenzie farm) but makes it go much further. Gravity is enough to pressurise the system with major energy savings compared with the pumping used previously. An additional 650 ha now has access to water, and the farms which were already connected are able to make much better use of the water they have. The water is shared with hydro generation at Highbank, with irrigation taking it September to May, and electricity generation during the winter when it is most needed.
Computerised monitoring of soil moisture using neutron probes allows water to be used very precisely when and where it is needed. Craige aims to leave enough soil capacity to absorb a 30 ml rainfall event without runoff or more importantly leaching, so that all available water, from the sky or the race, is used to best advantage.
His wheat produces 22-26 kg for every 1 ml of water spread on the wheat fields, and he is using half the flow he used in the old border dyke system. The key to this is not just the change to piped water, but the careful monitoring of soil moisture.
The precise application of water also eliminates runoff into the aquifer or streams - the aim is for every drop to be used by the plants rather than transporting valuable nutrients into waterways.
Associated with the moisture monitoring is the wheat calculator developed by Crop and Food, and the Foundation for Arable Research. The wheat calculator is a computerised tool which tells him exactly when the crop needs water and when it needs nutrients. It's available for free to FAR members from http://www.far.org.nz. Craige was involved with the trials developing this tool, and its use, along with information about the best varieties available identified by FAR for NZ conditions. Craige's detailed management has enabled him to increase yield by 50% while slashing nitrogen addition, using 250kg/ha inclusive (i.e. including nitrogen that is measured within the soil) for a 10t/ha crop of wheat and 200 kg/ha inclusive for Ryegrass.
Deep soil monitoring gives better information about available nutrients as the wheat and some vegetable roots go very deep (up to 2 metres for winter wheat). Fertiliser is applied during a light rain or under irrigation so it is readily absorbed. Phosphate and some micronutrients are used on a replacement basis.
The same careful measure - monitor - manage approach to pests leads to an Integrated Pest Management system which minimises use of pesticides. For example when the daily observation during the aphid season detects ladybird larvae, spraying is avoided in the knowledge that there will soon be an explosion of predators to take care of the aphids. If spraying is needed synthetic pyrethrums are used and organo-phosphates avoided. Minimising pesticide use makes economic sense as it protects the bees and other pollinator insects on which many of the crops depend, not to mention the family's own health.
The dairy unit uses the same approach to detailed information. Production from every cow is tracked and if production starts to drop or there are the first signs of mastitis she is automatically pulled out of the milking shed for checking. Current stocking rate is 4.2 per effective ha but as the milk solids price drops this will be cut back to avoid the extra cost of feed supplements (grain and silage).
Craige is using a nitrification inhibitor but has reservations. It works by slowing down microbial activity (and thus the conversion of ammonia into nitrate) but this is not always desirable for other reasons of soil health. In particular, broad scale application slows it down both on the urine patches, which are the main cause of nitrous oxide emissions, and in between them, where you would want greater microbial activity. Applying the same precision approach, he is looking at whether it could be applied only on the urine patches, or whether N fertiliser could be applied only between them.
We agreed that there is far more research emphasis on farming solutions which create a product to sell than on management practices which could be better for farmers but don't lead to a marketable product for suppliers. It is concerning that NZ's international negotiations to get techniques for reducing greenhouse emissions recognised and measurable under the Kyoto protocol are limited to nitrification inhibitors, because there is a strong commercial lobby for them, and nothing is being done to get recognition for management techniques like herd homes to reduce pressure on wet pastures.
I was also excited to see a biochar trial for the first time.
Craige and Roz's daughter Jemma is doing an agricultural science degree at Lincoln and her honours research project is biochar. Trial plots have been set up and planted with wheat. There are two types of char being trialled, one made from pine waste and one from hardwood; and three rates of application: 15, 20 and 30 tonnes per hectare. It is hoped that the lower rate will be effective because the logistics of moving that much material any distance will be energy intensive. The plots will be monitored over a number of years to see the long term effects.
Craige intends to start monitoring his soil carbon on the rest of the farm soon as an indicator of both soil health and carbon sequestration. Craige is chair of a soil carbon committee currently looking at a soil model that is being adapted to be accurate enough to use on NZ soils relative to our climatic conditions and farming systems.
This is a large, intensive farming operation which is reducing its environmental impact by maximising efficiency of all inputs. It is very much a knowledge based system, and the learning seems set to continue. If farming is to intensify to maximise yields per ha this seems to me to be the benchmark for how it needs to be done.
Many thanks to the Mackenzie family for sharing their knowledge with me.
