Improving plants’ water use efficiency and potential impacts from soil structure change - research investment opportunities. Final report to the National Program for Sustainable Irrigation. CRCIF Report number 3.14/1

Abstract

The Board of the National Program for Sustainable Irrigation commissioned this scoping document to assist in its research investment deliberations. The key questions addressed by this scoping study are: 1. What understanding, techniques and tools require further explanation or development to improve water use efficiency? 2. How well do we understand the impacts of long-term irrigation on soil structure? What are the effects of soil structure change (within and around the root zone on the flow of water and rate of movement along various pathways of salts? Key issues which the NPSI Board requested should be addressed in the document were: • Comment on the place that oxygenation may have in reducing the effects of water logging on production for various irrigation systems and secondary issues such as disease and pathogens at higher water temperatures. • How much is understood on the impacts of soil structure on water use efficiency, and in particular, managing the leaching fraction requirements of various soils? • Comment on the proposed work by Schrale to investigate issues associated with soil structure decline • Other than leaching efficiency and leaching fraction, are there other issues we do not understand that limit plants’ water use efficiency and salt disposal within the root zone?