Putaruru Farmer Makes Money Out of Muck

An effective effluent system is only a part of a far bigger picture of sustainability and growth for Putaruru farmers Martin and Judith Bennett. The couple were recipients of the 2006 Ballance Farm Environment Award, of which Martin is now a judge.

While committed to keeping their farm profitable, they have a deep appreciation that sustainability has to underscore any decisions they make on expansive and production increases. This was firmly in mind when they installed a feed pad and effluent irrigation system. They recognised the potential that lay in the Little Waipa stream on the farm boundary, but also the sensitivity of the catchment to run off.

The 118ha farm already had an in-ground sump system pumping direct to the farm from the dairy. After installing the feedpad, the farm’s old effluent pond became a storage and pumping source for effluent. A DODA PTO driven pump is used to push the effluent out through a travelling irrigator. A total of 23ha now receives valuable effluent well below Environment Waikato’s rate of 150kgN/ha. A single pass of the irrigator delivers only the equivalent of 35kgN/ha. 

A farm nutrient budget has played a key part in identifying the full value of the farm’s effluent output. Martin has been able to establish that he is in a position to mine some of the increasingly valuable nutrients in the soil profile without compromising production. The key to achieving this is extensive and regular soil testing to track nitrogen and potash levels.

With a flexible effluent system in place and plenty of storage, he can also closely control the timing of application to reduce potential nitrogen leaching, avoiding times of high rain fall and low growth rate periods. Good feed planning reduces the need for emergency dumps of nitrogen fertilisers in late winter and early spring.

Martin puts the value of nutrients saved using the system at $6,000 to $7,000 per annum, a figure only likely to increase as fertiliser costs soar. He budgets out system extensions at around $450/ha, an amount based on the three year period taken for installations to pay for themselves through fertiliser savings. Longer term he expects to have to apply cobalt and selenium to the areas not receiving any fertiliser, while P levels since 2000 have only dropped from 44 to 41.