Agriculture has been crucial in sustaining human populations in South Asia across dramatically variable envi-ronments for millennia. Until recently, however, the origins of this mode of subsistence in India have been discussed in terms of population migration and crop introduction, with limited focus on how agricultural packages were formulated and utilised in local contexts. Here, we report the first measurements of stable carbon and nitrogen isotope values in well-preserved charred crop remains from sites spanning the Neolithic/Chalco-lithic to the Early Historic in two very different environmental zones: tropical East India and the semi-arid Deccan. The results show that this approach offers direct insight into prehistoric crop management under con -trasting environmental constraints. Our preliminary results plausibly suggest that early farmers in India experimented with and made strategic use of water and manure resources in accordance with specific crop re-quirements and under varying environmental constraints. We suggest that the development of modern crop isotope baselines across India, and the application of this methodology to archaeological assemblages, has the potential to yield detailed insight into agroecology in India's past.