TECHNOLOGY ADVANCEMENTS


stewards of this precious natural resource to produce the food we eat. Technologies like irrigation informatics play a helpful role in informing daily operational decisions of the grower.


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Three core datasets have been transformative in creating irrigation informatics:


• satellite: Global sun-synchronous satellite programs like NASA’s Landsat and the European Union’s Sentinel have created a wealth of direct “earth observation” data that is free and publicly available.


• weather: The National Oceanic and Atmospheric Administration and the World Meteorological Organization have created thousands of weather stations across the globe, in addition to the hundreds of localized weather data systems (CIMIS, MESONET, etc.).


• soils: Collaborating soil scientists around the world (International Soil Reference and Information Centre) have made first-order estimates of public native soil properties at the root zone, at a global scale.


Due to this, the last five to 10 years have generated growth in what are termed agtech companies that have used this data and applied ambient computing, geospatial indexing and agronomic models to create field-bespoke irrigation informatics. Many agribusiness companies have incorporated these irrigation informatics into their own sensor and actuation platforms to deliver irrigation management services to the grower.


Demystifying this technology by highlighting its use through practical examples and reviewing its shortcomings will provide a simple path of adoption for growers who wish to improve their irrigation efficiency.


Economics of precision irrigation: Why should a grower care?


The economics of irrigation depends on the cost of pumping, volume and frequency of precipitation (offset), ratio of ground/ surface water, and the type of irrigation system (furrow/flood, sprinkler, subsurface drip, etc.). Irrigation is never free anywhere in the world in that a) the efficacy of irrigation is the largest component in determining yield, and b) the human productivity involved in managing water is non-zero.


ater sustains life. More than 70% of the global freshwater supply is used for our food production and, thus, water sustains life on our planet as we know it. Farmers play a critical role as


A typical, mature almond orchard in California’s Central Valley uses 4 acre-feet/acre 10% through its season. Given California’s temperate climate, almost 3.5 acre-feet/acre of that (>85%) is irrigated. Depending on whether it is a wet (surface water available in the snowpack) or dry year, the cost of water can range from $100 to $1,000/acre-foot (or more). Therefore, the total operating expense of irrigation water is between $350 and $3,500/acre.


Let’s assume it is an average of $2,000/acre (bundle fertigation, labor costs, etc.). Given the cost of production to be roughly $6,000/ acre, irrigation is 30%-40% of the cash operating costs of running a mature orchard and its single largest cost. Even if there was a perfectly irrigated field (which is never the case), just navigating the +1% to 10% year-to-year changes in week-on-week water usage results in a greater than 10% opportunity of savings or > $200/acre.


The economic incentive for savings is clearly there provided the grower can realize these incentives at a reasonable cost. Irrigation informatics makes it easier and simpler for the grower to realize these economic benefits.


Using data for informing irrigation


Irrigation science is constantly evolving. The Food and Agriculture Organization has published several methodologies over the years that aggregate research into a series of working papers. The following are two main steps considered to manage the optimal irrigation water usage in the agricultural field:


Step 1. Calculate the consumption – How much water “left” the irrigated area, which is a combination of several factors:


• Crop evapotranspiration (ETc, or ETa as actual evapo- transpiration): How much did the crop “drink,” how much evaporated and how much percolated down the soil in a given period of time. This is the most important factor driving irrigation planning and scheduling because it changes continuously. Reacting precisely to this dynamic nature is how one can achieve savings. The variability is due to several factors:


• weather changes: Generally, hotter, drier, windier and sunnier weather makes ETc go up. Colder, humid, less windy and cloudy conditions make ETc go down, sometimes as much as 20% week to week.


• phenological stages: Plants/trees go through various phenological stages (bud-break, flowering, fruit-set, etc.), during which water consumption rates increase and decrease.


Demystifying this technology, highlighting its use through practical examples and reviewing its shortcomings will provide a simple path of adoption for growers who wish to improve their irrigation efficiency.


irrigationtoday.org Summer 2021 | Irrigation TODAY 11


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