Increasing Water Productivity in Agriculture?

Here is a very good article (and some food for thought) on agricultural water productivity from people who have looked at the water business in agriculture around the globe for some time. The article clarifies the key hydrological and irrigation engineering concepts around the politically hot topics "water use efficiency", "irrigation efficiency", and "water productivity" in agriculture. A very good read even for non-scientists. I am copying the abstract below.


One of the authors of this study is Pasquale Steduto, a UC Davis alumni, now head of the Water division at FAO in Rome. He recently visited the Davis campus and gave an overview on the state of water around the globe, which you can check out here.

The article has just been published in the journal "Agricultural Water Management"(Volume 96, Issue 11, November 2009, Pages 1517-1524).

Increasing productivity in irrigated agriculture: Agronomic constraints and hydrological realities

Chris Perry^{a, ,} , Pasquale Steduto^b, Richard. G. Allen^c and Charles M. Burt^d

^aConsultant water resources economist, 17 Storey Court, St John's Wood Road, London NW8 8QX, United Kingdom
^bDivision of Land and Water, FAO, United Nations, viale delle Terme di Caracalla, 00153 Rome, Italy
^cDepartments of Civil Engineering and Biological and Agricultural Engineering, University of Idaho, Kimberly, ID, USA
^dIrrigation Training and Research Center, BioResource and Agricultural Engineering Department, California Polytechnic State University, San Luis Obispo, CA, USA

Abstract

Irrigation is widely criticised as a profligate and wasteful user of water, especially in watershort areas. Improvements to irrigation management are proposed as a way of increasing agricultural production and reducing the demand for water. The terminology for this debate is often flawed, failing to clarify the actual disposition of water used in irrigation into evaporation, transpiration, and return flows that may, depending on local conditions, be recoverable. Once the various flows are properly identified, the existing literature suggests that the scope for saving consumptive use of water through advanced irrigation technologies is often limited. Further, the interactions between evaporation and transpiration, and transpiration and crop yield are, once reasonable levels of agricultural practices are in place, largely linear—so that increases in yield are directly and linearly correlated with increases in the consumption of water. Opportunities to improve the performance of irrigation systems undoubtedly exist, but are increasingly difficult to achieve, and rarely of the magnitude suggested in popular debate.

Article Outline

1. Introduction

2. Water accounting

3. Transpiration and evaporation—definitions, interactions and typical relationships

4. Engineering options: how irrigation water is applied at project and farm level, and how this affects water use, consumption, and the demand for water

5. Crop production—how yield responds to water availability; how yield is affected by water stress; and how climate affects water demand and crop production

6. Conclusions

Acknowledgements

References