Phosphate and potash use also rose, though neither are close to previous highs.
Fert Research chief executive Philip Mladenov says the figures show farmers are reinvesting in their properties to improve production capacity and agricultural export potential.
"These are initiatives the fertiliser industry welcomes."
However, the nitrogen use raises concerns with independent fertiliser specialist Doug Edmeades.
"In terms of the increase P,K, S etc, this is a good sign: it indicates farmers are now replenishing their soil nutrient levels but the bad news is the nitrogen figure.
"A lot of fertiliser nitrogen is being used where it's not required and it's being used to cover up underlying soil fertility problems limiting clover growth, and we all know clover nitrogen is about five times cheaper than bag N."
Arguments that the nitrogen is needed to compensate for pests such as clover root weevil or clover flea, or recover from drought, don't wash with Edmeades.
"These are all excuses. In every case I look at there are underlying fertility problems."
The Fert Research announcement appeared to play down the nitrogen figure, despite it being 3% more than the previous peak of 355,000t hit in 2004-5.
"Elemental nitrogen use increased by about 8% over the previous year to 367,000 tonnes, which brings it into line with the previous seasonal peak use figure established in 2005," it quoted Mladenov.
"Since 2005 elemental nitrogen use has moved within a relatively narrow band, and use of this important and strategic nutrient is now
back to where it was six years ago."
Speaking to Rural News, Mladenov said he was "simply reporting the data as he saw it."
As for Edmeades' view farms are using nitrogen to cover up other problems, Mladenov acknowledges "there may be some individual farmers doing that but we don't see it as a trend."
Fert Research doesn't have a breakdown of where the increased use of the various nutrients is occurring, but Mladenov says a combination of improving farm incomes, particularly in the sheep and beef sector, and depletion of soil nutrient reserves, contributed to the increases overall.
Total use, at just over 3 million tonnes, was more than a third up on 2009-10's 2.3mt though still well short of the 2004-5 peak of 3.3mt.
Elemental potassium use is comparable with use 19 years ago and remains well below the 134,000t peak use hit in 2002-03.
Elemental phosphorus use also increased for the first time in three years to 147,400t but remains well below the 2004-5 peak of 218,600t.
