Dairy effluent could have lots of benefits for cropping
farms, but it is important to understand how its nutrients
are released, according to Craig Tregartha, of Plant and Food
Mr Tregartha was a speaker at the Foundation for Arable
Research's Arable Research in Action field day at the
Chertsey trial site recently.
Every effluent was different and it was important to know the
nutrient composition when deciding on application rates. It
also released nutrients more slowly than chemical
Understanding the rate of release was a critical factor that
influenced the amount of extra fertiliser that could be
required to reach yield targets.
Solid effluent had advantages over liquid or slurry, Mr
Tregartha said, in that it was lighter to transport and it
could be stored before being spread.
Applying a more concentrated effluent with less water could
reduce the cost of application and potential delay before a
paddock could be planted.
He said about a quarter of dairy farmers in Canterbury now
had solid effluent separators.
It had more benefits than just as a fertiliser, with its
organic matter improving soil structure and its range of
nutrients being in organic form.
The amount of effluent which may be applied to cropping
paddocks was controlled by regional council rules. These set
the total amount of nutrient (and nitrogen in particular)
that can be applied during a year.
Solid effluent waste is being used on crops at the site in a
trial funded by the Ministry of Primary Industries
sustainable farming fund.
Five plots are under scrutiny, one with half the effluent
applied in autumn, one with half applied in spring, one with
it only applied in spring, one with urea applied and one with
At this stage the urea plot was ahead but it was early days,
Mr Tregartha said.
By Maureen Bishop.