Grainswest - Spring 2022

Spring 2022 Grains West 16 PERSON PLACE & THING up one handful of soil. A litre of soil can contain 400 millilitres of water where we stand, but two metres away it’s 200 mil- lilitres. It’s not feasible to put thousands of those sensors into the soil at different depths and locations to accurately meas- ure an entire field. Now we have new sensor technology that uses microwave radiometer tech- niques to measure the reflectance in the microwave spectrum of the soil to deter- mine how much water is present in about the top half metre of soil. This type of sensor could be used to map out moisture over an entire field instead of just in one small volume location. It’s a really promis- ing way to create a 2D map. We’re working to come up with ways to take the data collected with the sensor and turn it into information for the farmer. I have students who measure soil mois- ture contents under different irrigation regimes, different depths and different time frequencies to see when it matches up with the sensor observations and when it breaks down. GW: What are the challenges in using this technology? WA: There are still some technical issues to work out. It is a bit sensitive to the water present in the crop, for instance. A potato crop would possibly tweak that signal a bit differently than a wheat or barley crop. Then there’s the aspect that this technology measures the total amount of water and not necessarily how much is available to the plant, which is what you want to know as an irrigator. It is quite a big project, and I think it highlights Lethbridge College’s strengths. And my group’s strength is very much on the ground. We understand soil and the interactions [of water] with topography. We’ve teamed up with the University of Alberta’s Control Systems group, a Depart- ment of Engineering team that analyzes data and designs algorithms to ensure electric and mechanical systems perform well. They are trying to incorporate [this technology] into this larger system for en- hanced control and decision-making over irrigation. We also have our industry partner Skaha Labs who developed the in- itial technology, but is interested in seeing how we can make it into a product that helps the irrigated agricultural sector. GW: In 2020, the Alberta government transferred management of the Alberta Irrigation Technology Centre (AITC) in Lethbridge to Lethbridge College. This soil mapping project, along with many others at the college, takes place on the AITC test farm. How has this move changed your research processes? WA: The move gave us mixed feelings. It was a wonderful facility already, and the loss of capacity and knowledge is felt, as the previous team of researchers and professionals that worked at the AITC are no longer there. However, for the college, it does mean we can now do our own controlled studies and continue to work with partners to ensure the mission of the centre can continue. With this space, we are able to desig- nate areas in our subsurface drip irritation field and under our variable rate irriga- tion pivots where we apply water strictly according to an alternative management strategy, such as withholding irrigation applications during certain growth stages. We can then evaluate the impacts on yield or crop water use efficiency. The more extreme strategies may cause crop or yield loss unacceptable to a commercial farmer, but this is important to evaluate in the framework of a research project. Being able to work on this farm has really taken the experimentation part of our research to a new level. We can design treatments, lay them out in plots and control the distribution of water, nutrients and tillage. We’re definitely grateful this was handed to us. GW: What emerging developments in irrigation are you most excited about? WA: Moving to the implementation phase of this new technology and data [from the soil mapping project]. A lot of people have found there is no silver bullet solution to better irrigation. There’s now this realization we need to bring togeth- er different tools and data sets to build a decision-making system for efficient, effective irrigation. We see this in re- search, these different fields of tech, data and on-farm research finally starting to come together. Appels and her Lethbidge College research group will carry out a three-year soil water mapping project that will employ a new type of sensor technology.