Dear Dr. M. Bhanarkar, You should contact to DR. Nachiket Kotwaliwale. He is a renowned Scientist in the field of sensors. He is an Agricultural Engineer and working as Principal Scientist at Central Institute of Agricultural Engineering, Bhopal (M.P.), INDIA. This an Indian Council of Agricutural Research (ICAR), New Delhi, INDIA
If you would like to look at off-the-shelf technology, to purchase, I have used wireless datalogger systems made by Decagon (http://www.decagon.com/) and have proven to be versatile and durable.