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    Comparing water input and water productivity of transplanted and direct-seeded rice production systems

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    Abstract
    Improving water use and nitrogen efficiencies is of overall importance to society at large – to conserve scarce water resources and prevent environmental pollution. Efficient cultivation practices for rice which had no yield penalty were not adopted by farmers because of the open access to water free of charge. Well-chosen combinations of policy measures are thus needed to stimulate adoption of new cultivation practices. We developed a multi-objective linear programming (MGLP) model to explore the impact of: (i) modified rice cultivation including water-saving irrigation on farm profit; (ii) water pricing and water quota government policies on adoption of modified rice cultivation by farmers; (iii) a combination of (i) and (ii) to achieve the objectives of both farmers and society at large, and (iv) to study the trade-offs between income, water and nitrogen use. The analysis was carried out on four rice-based farm types for the state of Tamil Nadu, South India. Model results showed that observed farm profit of all four farm types could be increased using current practices simply by optimizing land use for specific crops. Adoption of modified rice cultivation further increased farm profit. Water-saving practices were selected only when water pricing was introduced. Farm profits were reduced even at low water prices but were compensated by farmers through adoption of modified rice cultivation. The combination of policies that stimulate adoption of modified rice cultivation was effective in achieving both increased farm income and water savings. The required water prices differed across farm types and seasons and impacted poor resource-endowed farmers the most. Providing water quotas could protect the poor resource-endowed farmers. The model helped to identify the optimal water price and water quota for each farm type to achieve both the objectives of farmers and society at large. Opportunities for reducing water use and avoiding environmental pollution at acceptable profits are available for all farm types, but need to be tailored to the farmers’ resource endowments.
    Article Outline
    1. Introduction
    2. Materials and methods
    2.1. The modeling approach
    2.2. Data collection and model parameterization
    2.3. Model runs
    3. Results
    3.1. Step 1: profit maximization for current farm practices – base run
    3.2. Step 2: introduction of modified rice cultivation in the model
    3.3. Step 3: pricing water under current farm practices
    3.4. Step 4: pricing water with modified rice cultivation introduced to the model
    3.5. Step 5: pricing water with modified rice cultivation and water quota
    3.6. Step 6: trade-offs between water use and partial N-balance for target farm profits
    4. Discussion
    4.1. Validity of the model
    4.2. Model results on technology adoption and policy intervention
    4.3. Changing policies – possible in practice?
    5. Conclusions
    Acknowledgements
    References
     

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    作者:Cabangon, R. J., Tuong, T. P., Abdullah, N. B. 来源:Elsevier 发布时间:2011年07月13日