Second in charge on a 760-cow property, he won $3500 in prizes at the event, which included an anniversary ball, held at Auckland's Sky City Hotel on Friday night.
The category winner was 24-year-old Ruth Hone, of Taupo, who was the first woman to win the title. She took home $18,400 in prizes.
Mr Lavender (26) and his partner Chantelle Ross became engaged at Easter.
He said the awards night was a fantastic night and a great celebration of the New Zealand dairy industry.
''All the winners were thoroughly deserving,'' Mr Lavender said.
The study tour was a ''brilliant experience'' for him.
''The whole opportunity to network with the other top performers from around the country and hear how they went about things and how they got to where they were was hugely inspirational and encouraging for people like us.''
Southland-Otago 2014 Farm Manager of the Year, Jared Crawford, from near Riversdale, won the leadership merit award. Nick Bertram, of Featherston, was first, Simon Player, of Kerepehi, second and Phillip Colombus, of Oxford, third.
Southland-Otago 2014 Sharemilker/Equity Farmer of the Year winners Steve and Tracey Henderson, of Winton, were unplaced but Mrs Henderson won a gold medal in the ''Amazing Race'' around Auckland, which preceded the national awards.
Charlie and Jody McCaig, of Hawera, won the Sharemilker/Equity Farmer of the Year category, Kevin and Sara O'Neill, of Waiau, was second and Duncan and Kim Fraser, of Halcombe, third.
By Yvonne O'Hara.
