b"We also collect elevation data, very accurate RTK elevation, so either collected at the time in the field, or can get it through LIDAR or other sources. And we create topography and waterflow and accumulation models from that, that can also go into the final SWAT MAP. The final SWAT MAP can be combination of multiple layers that ulti-mately the goal is to depict the dominant variable characteristics in the field.SS: What are management zones?WA: The number one thing is youve got to get the management zones right, which means you have to group areas together that have similar response characteristics for the treatment you're talking about. Now, if we're talking about say sulfur responsiveness, we want to get zones that sort of determine where the most responsive soils to sulfur are, and where the least responsive soils to sulfur are, and maybe some gradients in between. If it'sA SWAT MAP image of a field captured by a drone, the field was bean stubble and shows topsoil loss a fungicide, for example, it might simply be some- throughout it.PHOTO: EVAN MACDONALDthing as simple as an on off where there is very poor crop or no crop that doesn't justify a fungicideeven had a lot of interest in doing things like ma-versus a good crop that does need a fungicide. nure and soil amendment applications targeting certain parts of the field that may need that a SS: What can management zones telllittle bit more than others. you about soil conditions in a field? Variable rate planting I think has a lot of prom-WA: A SWAT MAP is actually different for everyise. A lot of growers have the capability on their field. A zone 10 in one field is not the same as aplanters to adjust the spacing and a good base of zone 10 in another field, but it's just a generalinformation is a SWAT MAP. It's not just meant for framework. And I always say the best way to thinkpotatoes; it can be used for the other crops in the about it is really in the context of water, your zonerotation as well. one should generally always the driest, zone 10, the wettest.SS: Should you ever take a management An image of a field captured by a drone, the fieldzone out of crop production?was bean stubble whic has experienced topsoil loss.EM: Zone or grid sampling can be used in con- PHOTO: EVAN MACDONALD WA: Yield is really a dynamic thing that can vary junction with SWAT zones to build prescriptions.year to year depending on rainfall, frankly. Yields Some of the common ones for fertility for thingsdon't necessarily have a linear correlation to the like potash and mag and lime being spread. IveSWAT zones, sometimes they do. WINTER 2021 SPUDSMART.COM 59"