This is a typical uniform of the Volunteer Force in New Zealand. The NZ volunteers first brought in a khaki uniform with coloured collar and cuffs (facings) in 1891, but replaced it with a blue kit blue in 1895. However, a lot of units retained the older khaki version due to cost. After 1897, NZ volunteers could pretty much wear what they liked. Many new Companies of NZ volunteers were raised from 1898 onwards, and most of the new units used khaki uniforms with coloured facings, very similar to this.
Similar uniforms were worn by volunteers and militia in some of the Australian colonies from 1885 onwards, but the flavour of this pic is very much NZ. Note the side cap shown dates the photo from the early 1890s onwards, probably after 1895 if it is in NZ. By this time the leather gaiters shown were really only being worn in the UK, Canada, Australia and NZ, cloth puttees being used everywhere else.
Unlikely you can pin down the precise unit from the picture alone, as the uniform is pretty generic.
For comparison see a similar uniform worn by New Zealanders half way down this page:
http://tauranga.kete.net.nz/remembering_war/topics/show/1649-the-volunteers-early-military-history-in-the-hauraki-plains Note: all units had the side cap, but a lot also had either a hat (as here) or a helmet for formal wear.
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