Challenge
Knowing how much water is actually used at the dairy shed has a direct impact on the size of the pond needed to hold effluent. At a construction cost of $20,000 per meter, over-estimating the volume of water creates an additional cost that can be avoided.
Lloyd and Jo Morgan’s farm has a challenging landscape for dairy farming in Taranaki. There is over 100m fall from top to bottom, a lot of hills and valleys, and a lot of lahar (volcanic) mounds. They bought the land from the family in 1990 and converted it from runoff/support/sheep grazing to dairy farming. This involved a lot of flattening out to enable effluent spread. 175 effective hectare dairy farming with 400 cows.
Lloyd chairs the HADES (high altitude dairy environment solution) catchment group, whose primary focus is on effluent management. These high altitude farms get well over 2m of rain annually and often 100mm overnight which has a significant impact on effluent storage as well as available windows in which to disperse. The farm has 2 effluent ponds (oxidation) but Lloyds is investigating expanding the effluent pond system to comply with new consent conditions.
Example of effluent pond with Water to Grow device installed
Solution
The information from the Water to Grow system provides better information to calculate the requirements for effluent storage. The DESC model calculates the size of the effluent pond required based on the amount of shed water. The average used is 90 litres per cow per day. The data provided by Water to Grow system showed that Morgan farms daily water use is 67 litres per cow/day — a significant saving in the size of the storage pond. The pond cost is $20,000 per metre of storage, making for a significant reduction in the cost of upgrading the effluent pond.
