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Managing Irrigation Water to Enhance Crop Productivity under Water-Limiting Conditions: A Role for Isotopic Techniques
Closed for proposals
Project Type
Project Code
D12009CRP
1428Approved Date
Status
Start Date
Expected End Date
Completed Date
28 November 2012Description
Water limitation and drought threaten food security in many regions worldwide, and demands on limited water supplies for crop irrigation often are in sharp conflict with other needs. Water productivity (WP - biomass produced per unit of water input) and yield of crops varies substantially. However, underlying controls on WP and yield, even where other factors such as soil nutrient supply are not limiting, are poorly characterized for many water-limited situations. Crop transpiration efficiency (TE) and harvest index (HI), two important components of WP and yield, have not been adequately quantified under a range of water-limited conditions for important crop species. Therefore, the most optimal strategies for enhancing crop production with limited water through irrigation management have not been developed. This CRP will provide improved understanding and quantification of the non-productive component of crop evapotranspiration, soil evaporation, transpiration efficiency, harvest index and yield under a variety of environments for several important crop species. The information will be used to refine crop production models that are essential for optimising irrigation inputs under water limitation
Objectives
To improve the water productivity (production per unit of water input) of crops under water-limiting conditions
Specific objectives
(i) Quantify, and develop means to manage soil evaporative losses to maximise the beneficial use of water – the transpirational component of evapotranspiration.
(ii) Quantify, and develop means to improve the amount of biomass produced per unit of transpiration.
(iii) Devise irrigation and related management techniques to enhance the yield component of biomass production (Harvest Index).
Impact
1. Capacity Building:
i. The CRP brought new skill and cutting-edge new equipment in the use of isotopic and conventional methods for separating soil evaporation and crop transpiration to the seven counterparts in Asia, Africa and Europe.
ii. In Morocco, the counterpart is now working on a new large-scale national project to determine water losses in the irrigated land as a result of this CRP.
iii. In Vietnam, improved soil management (mulching) is being implemented on the coffee plantation in the Tay Nguyen Central Highlands to improve the water use efficiency, also as a result of the finding from this CRP.
2. i. The CRP also helped to nurture Master and PhD students. For example, in China the Chinese Agricultural University (CAU), three master students and one PhD students have been trained and graduated from this CRP.
ii. The CRP also opens up new opportunities to establish new collaboration between scientists in different Member States and institutions.
iii. Several TC projects (e.g. some counterparts in RAF5058 on 'Enhancing the Productivity of High Value Crops and Income Generation with Small-Scale Irrigation Technologies' and RAS5065 on 'Supporting Climate-Proofing Rice Production Systems (CRiPS) Based on Nuclear Applications') are implementing the techniques to improve water management.
3. A simple, fast and portable vacuum distillation apparatus for extraction water from soil and plant samples for isotopic analyses for the separation of soil evaporation was also developed as part of this CRP. With water isotope analyses becoming cheaper, easier and faster (e.g. the development of the fast and accurate laser isotope analyser), the bottleneck in sample throughput is often the water extraction time instead of the isotopic analysis of water. However, most conventional extraction techniques are laborious, time consuming and involved complicated setup with specially-made glass apparatus with the needs of liquid nitrogen or dry-ice, all these can be difficult to access in developing countries. The new apparatus developed in this CRP can be assembled using a commercial immersion cool, in placed of the liquid nitrogen or dry-ice for freezing water vapour. The method can be easily adopted at a relatively low cost and allows large number of samples to be extracted quickly for isotopic analysis. This apparatus has been adapted by many countries since the work was presented at the FAO/IAEA Symposium in 2012.
Relevance
Water limitation and drought threaten food security in many regions worldwide. Demands on the limited water supplies for crop irrigation often are in sharp conflict with other needs such as industrial and urban activities. Water productivity (WP - biomass produced per unit of water input) and yield of crops varies substantially. Crop transpiration efficiency and soil evaporation components of WP and yield have not been adequately quantified under a range of water-limited conditions for important crop species. This CRP has developed isotopic methodologies to quantify the soil evaporation component of water losses and determine the transpiration efficiency for several important crop species under a variety of environments. The CRP also developed a simple, fast and portable vacuum distillation apparatus for extraction water from soil and plant samples for isotopic analyses for the separation of soil evaporation, this will help to reduce the bottleneck in sample throughput for many soil water and hydrology studies.