b"ROUNDTABLE Expert views on best management practices in potato production.Unlocking Soil Secrets in Your FieldsSWAT MAPS are a digital map which charts soil, water and topography in fields in order to help growers better understand their fields. BY: ASHLEY ROBINSONWES ANDERSON Editors note: This interview has been edited for length and clarity.global fertility specialist with SWAT MAPS Spud Smart (SS): Why should growers care about getting a SWAT MAP made?EVAN MACDONALD (EM): As far as precision ag and potatoes goes, I think theyre a prime candidate for doing a lot of this work. They're a really expensive crop to grow and require a lot of inputs. So, even marginal gains or marginal savings and fertility or small EVAN MACDONALD gains in yield can add up to a lot in something like potatoes, whereas if it's a lesser value crop, those 10 per cents, and five per cents don't mean as much. When you're dealing with precision agriculture specialist at Cavendish Agri Services something that costs $3,000 an acre to grow or more, that can really add up. A lot of growers are already doing things like grid sampling for variable rate, fertility prescriptions, which I think is great. Anytime you can take into account the differences in your field and try and manage them, it's a good thing But SWAT can really help to target those prescriptions by managing those differences in soil, water and topography.WES ANDERSON (WA): There's a lot of things that ultimately affect the yield variabil-ity across the field Insects, diseases, all those typical pests, and all different crops can affect those things. Things like compaction, even a one-year whoops like spray drift, or maybe issues with the planter that affects plant population. There's a lot a lot of different things. And with SWAT MAPS, we try and focus on the stable soil and water properties that really don't change necessarily from year to year.SS: How is a SWAT MAP made?WA: What we typically do would be to go out simply in a half ton truck, and we have this thing in the back that's called a SWAT BOX. Within that SWAT BOX is a device that mea-sures electrical conductivity, so it might be an EM38, which is device that's actually been around a very long time in Canada, or in some cases, it might be a Topsoil Mapper. But ei-ther way, it's measuring the electrical conductivity of the soil at a couple different depths, which is related to solutes in the soil, it's related to moisture, it's related to texture, which again are somewhat all interrelated with each other. But at the end of the day, it's a really good tool for delineating salt gradients and soil texture. SUPPORTED BY:58 SPUDSMART.COM WINTER 2021"