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Water Productivity in Agriculture
Limits and Opportunities for Improvement
To find solutions to the water problems already facing many developing countries, we need a better understanding of how we have used water to grow food and to improve rural livelihoods.... This is the first in a series of books to be produced by the Comprehensive Assessment of Water Management in Agriculture Program, which is an international research, capacity- building and knowledge-sharing programme. Its purpose is to enable farming communities, governments and support organisations to make better quality investment decisions to meet food and environmental security targets in the near future and over the next 25 years. The book was edited by: JW Kijne, R Barker & D Molden.
The Editors Overview gets the book started: "...increasing the productivity of water means, in its broadest sense, getting more value or benefit from each drop of water used for crops, fish, forests and livestock while maintaining or improving ecosystems and the services they provide...." The book provides concepts, methodologies, constraints, and examples drawn from a wealth of experience in developing and developed countries. The book is then organised into a series of primary research papers. These begin with papers which set the language and terms of reference, and then detail specific aspects of specific country case studies.
I briefly review the first few papers and sections of the book, and then simply provide headings:
- Water Productivity Framework - paper proposes a common conceptual framework for water productivity, including a set of definitions and how they relate across different scales - for a farmer it means getting more crop per drop - for a society concerned with a river basin or a whole country's resource it means getting more value per unit of water resource. This interesting economics perspective looks at losses (transpiration) and evaporation, recycling, non-consumption uses. The paper moves the discussion beyond simple 'efficiency' into ideas of consumed fractions, and presents the problem of allocating water among users and multiple users - where the same water might be used twice or more. The paper gets into the judgement issues of the allocating agency or society;
- Economics of Productivity - Looks at relationship between efficiency, productivity and sustainability and examines confusions in definitions. Provides examples at plant, farm, system and basin levels. Also discusses potential for increasing productivity and economic efficiency through policy and institutional reform incentives - a good read;
- Concept of Water Efficiency - high water productivity does not necessarily lead to greater economic efficiency. This paper teases apart accepted economic wisdoms. The paper uses examples which show that unexpected offsite events can confound the efficiency findings derived from local considerations only. Water savings do not necessarily lead to increased water productivity - a few equations in this one, but the text helps those who can't easily read algebra;
- Rice Production in Water Scarce Environments - fascinating picture of rice crops in Asia in water scarce environments moving from anaerobic soils to aerobic soils as water supplies are reduced partly driven by reducing water quality. These changes have dramatic consequences for soil organic-matter turnover, carbon fixing, nutrient dynamics, release of nitrous oxide from soils - and so on;
- Saline & Alkaline water and High Productivity - another fascinating examination of irrigation with saline water. Gets into detail of low salinity around root zone, but higher elsewhere. Talks of mixed waters. Development of salt tolerant crops. Raises questions about understanding effect of saline water penetrating into underground aquifers. Suggests this form of irrigation should be confined to regions that are very dry;
- Opportunities for Increasing Productivity through Plant Breeding - paper reports on work of CGIAR - Consultative Group on International Agricultural Research. Looks at possibility of genetic or other breakthrough in this area of research - considers breeding which could reduce transpiration, increase drought tolerance;
- Management of Drought in ICRISAT Cereal & Legume Mandate Crops;
- Water Productivity in Rain-fed Agriculture - Smallholder Farmers in Drought-prone Tropical Agroecosystems;
- World Water Productivity - Situation and Options;
- Improving Water Productivity in Dry Areas of West Asia & North Africa;
- Efficient Management of Rainwater for Crop Productivity and Groundwater Recharge in Asia;
- Water Productivity in Forestry and Agroforestry;
- Water Productivity and Potato Cultivation;
- Rice-Wheat Cropping Systems in the Indo-Gangetic Plains;
- Land and Water Productivity of Wheat the Western Indo-Gangetic Plains of India and Pakistan;
- Reform of the Thai Irrigation Sector;
- Upscaling Water Productivity in Irrigated Agriculture;
- Improving Water Productivity through Deficit Irrigation: egs from Syria, North China Plain & Oregon USA;
The book is completed by two appendicees - one on transpiration and another addressing agronomic practices for increasing crop water productivity. There is a detailed index. The hardback book runs to 330 pages.
The papers are liberally illustrated with graphs and tables.
This is a text for policy developers and researchers involved in water allocation and sustainability and economic development. The papers have all been well edited to make them readable - and not full of undefined jargon. Some of the papers have needed to revert to the language of mathematics to communicate their ideas with precision, but in all cases I found it was possible to retain the gist of the key ideas involved without having to fully immerse myself in the equations. The use of many case studies from around the world - and from the local farm up to river basin and beyond is especially commendable in aiding understanding and engagement.
The book and its papers are full of new ideas and new thinking on the topic of water use in agriculture. I recommend it to those interested in water policy, wanting to get some understanding of possible future directions for water policy thinking and policy development.
Water Productivity in Agriculture was published in 2003 in association with The International Water Management Institute. (based in Colombo, Sri Lanka).
The isbn is 0-85199-669-8 (hard cover).
It was published by CABI Publishing.
Email - cabi@cabi.org, and website: www.cabi-publishing.org
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Joel Cayford
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