India is the world's third largest producer of cotton, after China and the United States of America. Cotton production has been the special pride of India for many centuries. Cotton, the most extensively grown cash crop has been known in Tamil Nadu since 1790, when the Bourbon cottonseed obtained from Malta and Mauritius were first distributed among the cultivators. Energy is a primary input in the agricultural process. At present, more than fifty per cent of energy used in agriculture comes from non-renewable sources. It was observed by S. Singh and J.P. Mittal that the use of modern inputs is biased towards irrigated crops mainly because of higher degree of complementarity of modern inputs with irrigation. Hence the present study attempts to examine the substitutability and complementarity between renewable and non-renewable energy inputs used in the production of cotton particularly two popular varieties namely MCU-5 and LRA-5166 varieties in Tamil Nadu.

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