- Author: Ben Faber
I just came across a wonderful summary of the different methods that can be used to schedule irrigations based on plant sensors. In th past this is has been labor intensive and not easily adapted to commercial agriculture. This review covers some of those problems and how they have or not been overcome by new technologies. Of course, plant-based techniques are the not the only way to schedule and may only be part of the variety of methods used, such as soil-based ones like tensiometers; or weather-based ones, like ET. A shovel and just looking at trees helps too.
Plant-Based Methods for Irrigation Scheduling
of Woody Crops
The increasing world population and expected climate scenarios impel the agricultural sector towards a more efficient use of water. The scientific community is responding to that challenge by developing a variety of methods and technologies to increase crop water productivity. Precision irrigation is intended to achieve that purpose, through the wise choice of the irrigation system, the irrigation strategy, the method to schedule irrigation, and the production target. In this review, the relevance of precision irrigation for a rational use of water in agriculture, and methods related to the use of plant-based measurements for both the assessment of plant water stress and irrigation scheduling, are considered. These include non-automated, conventional methods based on manual records of plant water status and gas exchange, and automated methods where the related variable is recorded continuously and automatically. Thus, the use of methodologies based on the Scholander chamber and portable gas analysers, as well as those of systems for measuring sap flow, stem diameter variation and leaf turgor pressure, are reviewed. Other methods less used but with a potential to improve irrigation are also considered. These include those based on measurements related to the stem and leaf water content, and to changes in electrical potential within the plant. The use of measurements related to canopy temperature, both for direct assessment of water stress and for defining zones with different irrigation requirements, is also addressed. Finally, the importance of choosing the production target wisely, and the need for economic analyses to obtain maximum benefit of the technology related to precision irrigation, are outlined.