How can you find old tile lines without spending hours digging holes? During our webinar on Wednesday, Kevin Erb, Conservation Professional Training Program coordinator at the University of Wisconsin-Madison, Division of Extension, discussed available strategies and tools, most of which use information that the farmer already has, or that is readily available.
Knowing where old tile lines are located makes upgrading easier, and due to the connectedness of tile systems, the impacts of tile issues can stretch beyond the field or property line. Erb shared some history of tiling, explaining that due to the difficulty of installing clay or concrete, tile systems were not installed in neat grid patterns, but instead from wet spot to wet spot, which can make locating them difficult generations later.
Erb explained that air photos can be a helpful tool, but that not everything that looks like tile on old air photos is tile. Because of this, it’s important to look at multiple years of air photos to determine what actually is tile. GIS software can be helpful to overlay the years of photos if you have it available, but you can also assess air photos by hand, by comparing multiple years of photos side-by-side. Google Earth’s time machine function allows you to click through multiple years of data, which can enable you to see things that show up on some years, but not on others, due to soil moisture and temperature variations.
With combinations of air photos, lower-level drone photos, and field observations, you’ll start to be able to map out where the drainage tiles are located. It’s also important to mark the location of tile blowouts when you see those in fields, to better understand the system. Yield maps can also be useful tools for determining drainage tile locations. Once you’ve started to create your tile map, yield data can help you located areas of unmapped tile and help you identify areas where your tile might not be working well.
As you build your tile map, Erb suggested color coding the tile lines by the sources through which you found them. This can help you see where there might be data missing and may help you identify areas that you need to do further research on to find the tile lines. It is also helpful to map more than just your field, including at least every field next to yours, if not the entire section, so that you can better understand the complete picture of tile drainage in your field.
To learn more about creating a tile map, other non-Google sources of air photos, the Budweiser/Euchre method, and other technology that can be used to map tile lines, such as ground penetrating radar, watch the full webinar!
Join us on Wednesday, December 9 at noon for “The Cost and Benefits of Agricultural Water Conservation: An Economist’s Perspective,” a webinar presented by Wendong Zhang, assistant professor and extension economist at Iowa State University.