28 July 2014
New model predicts pasture response to nitrogen
A new model that can more accurately predict pasture responses to nitrogen is now available for farmers throughout the
country.
The model is the first product resulting from farm nutrient co-operative Ballance Agri-Nutrient’s $19.5 million, seven
year Clearview Innovations Primary Growth Partnership programme, jointly funded by the Ministry for Primary Industries.
Backed by sound science and extensive research, N-Guru™ is decision support software, designed in partnership with
AgResearch, to improve the efficiency of nitrogen use on New Zealand pastoral farms.
A soil ‘total N’ test is carried out as part of routine soil testing. Where total nitrogen varies sufficiently across
the farm, the model can be used to determine variable nitrogen use instead of applying the same amount of nitrogen
across the whole farm.
The software is already available for farmers, with Ballance sales consultants now offering N-Guru as part of a
fertiliser recommendation to help farmers make better decisions about nitrogen use.
The co-operative’s Science Manager, Aaron Stafford, says they’ve piloted the software with farmers, and they love it.
“It’s a no-brainer, because with N-Guru we can now more accurately predict the relative pasture response and confidently
tailor our advice accordingly.
“We are always looking at ways to support farmers in increasing production while making the best use of their fertiliser
budget and reducing the impact on the environment. This is another step forward in our ability to give expert advice,
adapted to each part of the farm and firmly based on knowledge gathered from a large number of pasture response trials
carried out nationally.”
N-Guru offers a valuable model to assess the benefits of varying the nitrogen application across the farm rather than
using a single uniform rate, which enables farmers to target nitrogen applications to pastures that will produce the
best response.
“By improving nutrient use efficiency through the strategic and targeted use of nitrogen the risk of associated nitrogen
loss is reduced, and the cost benefit of fertiliser-nitrogen application increases.”
Development of the N-Guru software is ongoing, based on feedback from farmers.
N-Guru is expected to make a significant contribution to the Clearview Innovations PGP programme target of a 50%
improvement in nitrogen use efficiency on New Zealand farms.
SIDE PANEL: N-Guru in action
The following example shows how N-Guru could be used to provide production benefits:
Soil testing of a 100 ha dairy farm reveals the following:
• 50 ha has Total N of 0.7% (high N area)
• 50 ha has Total N of 0.3% (low N area)
A difference of this magnitude is considered significant enough to warrant the use of N-Guru.
N-Guru models the following pasture responses:
• 7 kg DM/kg N applied, in the high N area
• 13 kg DM/kg N applied, in the low N area
Without N-Guru, the farmer would typically apply 30 kg N uniformly over the farm. This could be expected to produce a
10:1 response, resulting in a total of 30,000 kg DM. With N-Guru, the farmer could apply 60 kg N/ha to the low N area
(e.g. split over 2 applications), and none to the higher N area. This would produce a 13:1 response, resulting in a
total of 39,000 kg DM.
If the extra 9000 kg DM is converted to production at 12 kg DM/kg MS, the result is an additional 750 kg MS. At a payout
of $6/kg MS, this is an economic gain of $4,500 for the farmer.
ENDS