The value of using effluent to grow maize

Waikato dairy farmers will have the opportunity to find out how effluent can be used to boost the growth of maize silage crops at a series of on farm field days in December.

The concept of planting maize crops in nutrient-rich effluent blocks and applying effluent, instead of bagged fertiliser, to crops grown in paddocks that have low soil fertility has been very effective overseas.

"Effluent blocks are quite often overloaded with nutrients, especially nitrogen and potassium, so it makes sense to plant in these areas,” said Environment Waikato’s sustainable agriculture coordinator Gabriele Kaufler.

“Although overseas research has helped us understand some of the gains that can be achieved, it’s important that we understand how to make this technique work in the context of New Zealand’s farm systems and regional rules. For example, we want to know how much, if any, fertiliser or side dressing is necessary when growing maize on a high fertility effluent block.

“Thanks to a grant from the Government’s Sustainable Farming Fund we’re now running trials on four farms in the Waikato region in conjunction with the Foundation for Arable Research, Dexcel and Genetic Technologies Ltd (Pioneer). Over the next three years these trials should give us the answers we’re looking for. In the meantime we’re keen to start discussing the opportunities, potential benefits and implications of this technique with farmers.”

Under Environment Waikato’s Regional Plan, irrigating effluent to land is a permitted activity. This means farmers don’t need a resource consent, but they must follow certain rules. Some of these are:

not applying more than 25mm per application to prevent run-off
applying a maximum of 150kg of nitrogen per hectare per year on pasture and 200kg of nitrogen per hectare per year on maize
ensuring their effluent doesn’t pond on the land surface or create any odour or discharge nuisance outside their property boundary.

Farmers who apply a higher load of effluent (up to 200kg of nitrogen per hectare per year) on their paddocks must be able to clearly demonstrate that the paddocks will be used to grow maize. Ms Kaufler suggested that the best way for farmers to do this is to make a few simple notes in their nutrient management plan.

“Given the problems that can occur when too much effluent is irrigated onto pasture it’s important that farmers apply no more than the amounts specified in the Regional Plan, and that they identify the different treatment areas in their nutrient management plan.

“In the case of effluent applied to paddocks earmarked for growing maize, farmers should note things like the size and location of the blocks that will be used for maize and the date the blocks will be cultivated.”

Next month’s field days will be held on each of the trial farms, where various treatments have been set up to investigate this technique.

All field days start at 10am and run to 12.30pm followed by lunch.

Date




Name


Location
Fonterra

supply number



3 Dec.




Wyn & Tony Brown


Matai Rd


Matamata


77444



4 Dec.




Mike & Sue Visser




Ngahape Rd


Otorohanga


74513



11 Dec.




Russell & Alison Gibb


Proctor Rd


Orini


72318



12 Dec.




Jim & Susan van der Poel


Hams Rd


Ohaupo


73584