A Sustainable Approach to Dairying

June 2017

A soil-based approach to sustainable dairying in Waikato

Rural Delivery first visited Max Purnell in 2007. At the time, he was three years into a six-year term on the board of AGMARDT, a body that was set up to support innovation and leadership in the agricultural sector. Max is now a “semi-retired” dairy farmer, and his daughter Jasmine now milks the cows for supply to fresh milk company, Green Valley Dairy. 

Max has spent a fair chunk of his life working to build up soil carbon on his farm, aiming for a more natural and sustainable way of farming. His goal is to develop deep residual rooting systems and “sweet smelling” soils. 

By improving soils Max believes the quality of pasture grown, and the quality of animal products produced off that pasture, is improved as well. 

For the past several years he has experimented with a “rolling fallow” in rotation around the farm, allowing some paddocks to grow unharvested except for occasional light grazing to remove seed heads. 

Fertilisers such as superphosphate and nitrogen have not been used on the property for some years and Max says despite that (or because of it) soil depth and quality has increased, and a considerable amount of carbon has been sequestered. 

The property is 89 hectares, 60 of which are flat, and the rest rolling. There’s also a 30ha on a runoff a few kilometres away. 

A herd of around 110 cows supply milk that is sent to Green Valley Dairies, an independent fresh milk company operating just south of the Bombay Hills. 

Max says supplying Green Valley fits with his and daughter Jasmine’s farming philosophy. They both believe in producing products from healthy soils. Green Valley doesn’t offer a premium as such for the milk but it does offer “a lack of volatility” which Max says means a lot. 

The arrangement is not on the basis of the traditional kilograms of milk solids per litre, but on litres of milk delivered. 

They are currently into their fourth year as suppliers to Green Valley. Max understands some of the fresh milk from Green Valley ends up in China. 

Max credits Dr Christine Jones with inspiring much of the work that has been done on their farm. Dr Jones is an Australian scientist who believes improving in soil carbon levels is one of the keys to overcoming the environmental challenges facing farming. She says farmers depend on soil for their livelihoods yet many of them have a limited understanding of the profoundly diverse ecosystem that is beneath their feet. She says, “when we stand on the soil we’re standing on the rooftop of another world.” 

Conventional wisdom is that pastoral farming increases soil carbon, but recent research has shown that some NZ soils have actually lost carbon in the past two decades. There is also some work showing that use of superphosphate and nitrogen to boost pasture growth has the effect of reducing soil carbon. Christine says things have grown for centuries without synthetic nitrogen being added as fertiliser.   She says there are a lot of myths and misconceptions put out by fertiliser companies. 

Organic farmers and those who farm “biologically” without manufactured chemical fertilisers would argue their efforts to encourage soil biology - such as bacteria, fungi and worms, plus the use of a wider range of pasture species - results in the build-up of soil carbon in the form of deeper plant roots and a multitude of soil organisms. 

Max points out that many farmers are using biological practices that enhance soil growth, and that his is not the only way. However, they all need help to improve their results and get a better understanding of soil carbon.