The EIP Focus Group on Water and Agriculture brought together 19 experts, who started their work in June 2015 and delivered their report in March 2016.
Discussions were framed by an initial document written by the coordinating expert, partly based on a survey circulated to the group's members before the first meeting. In agreement with this document, the main strategies to tackle under water scarcity have been identified. They include measures currently applied at farm level or promising ones.
The group chose to classify these strategies into three main categories:
- i) practices to increase water availability for crops and livestock,
- ii) the efficient use of water (including irrigation efficiency), and
- iii) farm resilience under water scarcity.
Many other factors than water affect productivity in both rainfed and irrigated commercial farms, and the causes of these factors must be understood.
Water availability may be increased by strategies that reduce water losses or increase the capacity to store the water to be used by crops or livestock. Among the identified strategies, conservation agriculture and covering the soil surface by residues or mulching were considered the most effective for conserving water.
Given the available water, there are strategies aimed at increasing crop production using that water:
- i) choosing a cultivar or species with high water productivity,
- ii) using available water more efficiently and,
- iii) in the case of irrigation, increasing irrigation efficiency.
Any improvement in crop, pasture and grazing management, and in feeding or in crop and animal health will thus result in an increase in water productivity and output of the system. Four strategies were identified as potentially more effective: choosing crops with high rooting ability, improved cropping management (fertilisers, pest and diseases, crop rotation, irrigation) aided by decision support systems, and precision irrigation monitored by remote sensing.
Some strategies profit from farm spatial differences to increase resilience under water scarcity. In these terms, large farms have more scope for zone diversification and timely operations and can afford their own equipment and labour. Among the discussed on-farm strategies, crop diversification and linking to networks were identified as potentially more effective.
Some strategies require fine-tuning for adaptation to local conditions, may not be economically viable, or pose environmental problems. Some of these strategies require research to make them viable on-farm. Although not specifically addressed by this FG, a major concern of many of its members is that on-farm strategies must be combined with efforts at a higher scale than the farm to be really effective at conserving water and using it efficiently.
Some general failure factors and barriers for adoption were common to several strategies. Little is known about the economic implications of farmers adopting most of the proposed strategies, particularly if these are recently introduced or uncommon. Similarly, there is a lack of evaluation of strategies at farm level to show the impact on water conservation and the return to investments. There is also a lack of knowledge regarding long-term or environmental benefits of strategies in local conditions. This type of demonstration or research is rare as most public agricultural research is focused on frontier knowledge. Additionally, there is little institutional and policy support when significant training, technical advice or fine-tuning research are required.
Research Needs from Practice
For most strategies, their effectiveness in water conservation at farm level and the economic return are unknown. Clear protocols for systematic on-farm research to evaluate strategies are needed; and often, understanding the impact at higher scales than the farm (e.g. watershed) will be required to have a global significant impact on water conservation. Similarly, economic and environmental risks associated to any strategy must be studied and well understood. Transparent cost-benefit analyses are required before any promotion among farmers. Some strategies require long-term studies to show agronomic benefits, in particular those aimed at improving water holding capacity and water infiltration by increasing soil organic matter: conservation agriculture and maintaining soil surface covered with residues, mulching, cover cops or green manure, and crop rotation.
Decision Support Systems (DSSs) can be used to improve crop and irrigation management but should be calibrated and evaluated for local conditions. They also need further tests and research to widen their applicability in a range of environments and crops; to make them more user-friendly; and to show clear benefits in practice.
Regarding irrigation efficiency, there is a need to develop and refine cost-effective, easy to use plant- based sensors to monitor the actual crop water use, as well as their implementation in DSSs to provide real time recommendations for irrigation scheduling in different crop species. The interpretation of the sensor data should be based on a thorough understanding of the crop physiology to ensure that the DSS are reliable. Research is also needed to improve regulated deficit irrigation (RDI) strategies to broaden the number of species, environments and soils where they can be applied. Furthermore, studies are needed to validate and fine-tune the application of online services, RDI protocols and precision irrigation approaches.
In precision irrigation, field crop variability is identified and quantified using remote sensing images or in-field measurements; however, research is needed to develop protocols and clear prescriptions for taking decisions regarding water depth of applications. Site-specific variable rate irrigation systems must be tested and evaluated for local conditions.
Ideas for Operational Groups
Focus Group members proposed several ideas for Operational Groups to develop viable strategies: local adaptation of conservation agriculture; increasing soil organic matter; proper tillage to reduce soil compaction; improving crop rotation and increasing crop diversification within farm and within plot; identifying spring- summer crops less sensitive to low temperatures for earlier sowing; determining local benchmarks as references for irrigation performance and crop productivity and identifying sources of on-farm yield gaps; optimising irrigation with crop water balance and soil sensors, supplemental irrigation or adoption of regulated deficit irrigation considering yield or quality; precision irrigation aided by remote sensing; site-specific variable rate irrigation; use of alternative water sources; and use of poor quality water and innovative solutions for improving or managing it.
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