Walton Farm Cows
Environment
New pasture species with AR37 endophyte (click to enlarge)
Feeding maize silage and supplements (click to enlarge)
While intensification has lifted production in the dairy sector – milk solid production per hectare rose 34% between 1994 and 2002 – it is clear that this increase has come at some environmental cost. The use of nitrogen-based fertiliser to boost grass growth has increased dramatically: between 1996 and 2002, the use of nitrogenous urea fertiliser alone jumped 160%.
If applied excessively, nitrogen leaks into the wider environment. Nitrogen is highly mobile and easily enters streams and groundwater reservoirs, leading to the deterioration of groundwater quality and the eutrophication of fresh and coastal waters. It is a particularly insidious problem as there is a lag between the application of nutrients and their appearance in waterways.
The deterioration of Lake Taupo's water quality today is due to nitrogen applied to adjoining farmland up to 50 years ago. The other major contaminant produced by intensive dairying is faecal matter: a single cow produces as much sewage as 14 humans.
On the demonstration farm, effluent is piped to a storage pond and then sprayed over paddocks as a manure slurry, using a system of pumps, rain guns and a travelling irrigator. The farm has a part-time worker dedicated to effluent disposal. Investment in effluent disposal pays for itself through savings in fertiliser costs. But because not all of the herd's feed is grown on the farm, the Bennetts have to take great care not to apply more nutrients to the land than are taken from it. This is particularly important given the area's high rainfall and the farm's high water table.
Fertiliser is only applied where necessary. On Walton Farm, Overseer nutrient budget software developed by AgResearch provides a mathematical model that helps the Bennetts and their fertiliser consultant from Ravensdown Fertiliser Cooperative work out exactly what quantity of nutrients are needed on each part of the farm. David and Raewyn use precision farm mapping software, Resolution, to plan the application of fertiliser, as well as activities like maize and regrassing.
