There are a number of farms which accept volunteers in Auroville. Conditions relating to hours and possibilities for accommodation vary widely and will also vary according to the time of year. Everywhere tends to get very full and busy during the guests season - December to March - and it will be best to book ahead if you want to come during this time.
If you want to stay on a farm, most farms have a minimum time of two weeks or more. If you want to stay somewhere else in Auroville and volunteer on a farm this is also possible and will mean that you can work for a shorter period. You will need to contact the farm individually to find out exactly what the conditions are for staying and working there. No farm in Auroville is able to offer a work exchange although if you are interested in this there are one or two farms who will consider it after a trial period. You will probably need to work for at least a month to make sure that both sides are happy with the arrangement and you will need to stay for at least three or four months after that to make it worthwhile for the farmer. Farmers try to keep the costs as low as possible for volunteers but the reality is that some money is needed to pay for the upkeep of the accommodation that volunteers use as this can very rarely be recovered from the sale of farm produce.
Farms vary a lot in the sort of work you will be doing. Some farms have animals like cows and chickens, but some farms focus more on growing vegetables or grains like rice. Hours of work vary but many farms like to start early in the morning when it is cooler and more comfortable to work. Again, it depends on the farm and you will need to contact the farm individually.
For more information and a list of farms that take volunteers you can contact the Farm group office email@example.com
Read more on volunteering in Auroville.