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Wageningen Universiteit (2008)

Saving water ? : analysis of options for rice-based farms in Tamil Nadua, India

Senthilkumar, K.

Titre : Saving water ? : analysis of options for rice-based farms in Tamil Nadua, India

Auteur : Senthilkumar, K.

Université de soutenance : Wageningen Universiteit

Grade : PhD thesis 2008

The looming water crisis and water-intensive nature of rice cultivation are driving the search for alternative management methods to increase water productivity in rice cultivation. Solely reducing water use in rice resulted in proportional reduction in yield, hence various management practices of rice cultivation have to change simultaneously to enhance water productivity, without reducing the productivity of other factors, primarily land (i.e. yield), labour and fertilizer. Experiments were conducted under on-station and on-farm conditions to compare rice production using modified methods of planting, irrigation, weeding, and nutrient management with conventional methods of cultivation. An yield advantage of up to 1.5 t ha–1 was achieved with a water-saving of 40% for the combination of modified methods over conventional methods. However, adoption by farmers remained limited due to the increased labour demand for modified planting, unwillingness of agricultural labourers to change practices, difficulties with modified nursery preparation and gender issues related to mechanical weeding. Potential for adoption of novel cultivation practices depends on the structure and functioning of the farm, hence four rice-based farm types were identified based on biophysical and socio-economic characteristics of the farms using principal component analysis. Opportunities exists in all four farm types to adopt one or more components of modified rice cultivation, but change in government policies are needed to improve adoption such as rules and regulations, pricing, institution building and infrastructure development, as well as training and education to farmers. An identical set of policy interventions cannot be applicable in all farm types since current resource use efficiencies and adaptability to changes differed substantially. Hence, we quantified current use efficiency of water, labour, nutrient and capital in all four farm types both at crop and farm level and qualitatively assessed the possible impact of different policy measures differentiated per farm type. A multi objective linear programming (MGLP) model was developed to explore quantitatively the impact of government policies introducing water pricing and water quota on adoption of modified rice cultivation including water-saving irrigation and related impact on farm profit. The combination of modifying rice cultivation and water pricing was effective in achieving both the objectives of farmers (i.e. maximizing income) and the society at large (i.e. increasing the use efficiency of water resources through inclusion of modified rice cultivation in the farming plan). The required degree of water pricing has to be kept low since higher prices lead to decrease in farm profit. Impact differed across farm types and affected poor resource endowed farmers most. Providing water quota can be an option to protect the livelihoods of poor resource endowed farmers. Apart from government water pricing and quota, policy instruments such as training and education in modified rice cultivation practices, development of irrigation infrastructure and organised cooperative management of commonly available water resources could have impact on the adoption of modified rice cultivation but this remains to be clarified.

Mots clés : oryza sativa / rice / cropping systems / plant water relations / irrigated farming / water management / use efficiency / optimization methods / tamil nadu / india / multiobjective programming

Présentation et version intégrale

Page publiée le 19 mars 2009, mise à jour le 1er juin 2022