Water and Nutrients
Leaching is the movement of contaminants carried by water through soil into waterways. The risk of leaching is increased when the soil is saturated, because this makes it easier for contaminants to move through the soil. NIWA weather stations, soil moisture indicators, variable pivot irrigators, GPS-tracked fertiliser and the three-phase effluent system are used to limit water and nutrient application and mitigate the risk of leaching.
Fertiliser trucks spread nutrients onto the pastures to encourage grass growth. All fertiliser is GPS-tracked for proof of placement which ensures there is no overlap of application. Overlap loads the soil with more nutrients than desired and can cause leaching.
Variable pivot irrigators allow the farm managers to control how much water is used. Variable rate irrigators allow water to be spread at different rates, based on soil depth and moisture levels. This further reduces the risk of over saturating the soil.
Raw effluent is taken from the dairy shed and into a stone trap where all heavy materials are removed. The effluent then moves into a lined pond where the organic solids settle and the green water is drained into a second lined pond. From here the effluent is pumped onto 100% of the pivot area. By pumping the effluent over all the irrigated area the application is diluted and this limits leaching.
The NIWA weather stations provide actual data such as rainfall and soil temperature and weather predictions are are used to assess future climatic conditions. Soil moisture indicators show farm managers the water saturation in the soil. This means farm managers can reduce water use and the risk of leaching by irrigating when soil moisture levels and weather forecasts are acceptable.