Mobile Data Tools Used in Soil Survey for the First Time

by | January 25, 2012
Category: Blog

In December, AfSIS sent two staff members to Ethiopia to help Ethiopia’s Agriculture Transformation Agency launch a new country-wide soil research initiative. The soil collection teams used Android-based tablets for their work, marking the first time that soil research has been conducted in this way. Each team carried one tablet and used it in place of dedicated GPS devices, paper surveys, and digital cameras. While much of the experience of the soil survey was similar to our previous socio-economic research survey, we have a few new insights to share.

Hardware Considerations
The soil research survey reaffirmed our preference for 7-inch tablets over phones. The tablets allowed the team leader to teach others and show the day’s route to those gathered around. The tablets’ batteries made it through each day of research once we made sure to diligently use airplane mode and keep the screens turned off whenever possible.

Because we were literally out in the middle of open fields for much of the day, we also had to be much more conscious about not leaving the devices exposed to sunlight and the resulting high temperatures. Extreme heat can irreversibly damage the devices, but even more of a concern is the impact of heat on battery life.

The experience also reiterated the importance of the “jean pocket test.” In other words, look for devices that will fit in a back pocket of your pants. Anything bigger requires you to have a satchel, case, or bag with you at all times.

Order of Soil Research Questions
The soil research survey did not involve interviewing, as opposed to our socio-economic survey, which had. Instead, the soil data that was collected was observational, with many people making observations at one site that all needed to be recorded. With paper surveys, a team leader could jump around the paper filling out different sections as other team members called out information to her. But with the digital form, we needed to pay more attention to the order of the questions and the work flow of the team. Because we recognized this challenge early and planned for it, things went smoothly. Attention definitely needs to be paid when non-interview type surveys are converted from paper.

Using Data-enabled Devices/Challenges with Photos
We used data-enabled tablets (the type that take SIM cards) for this work rather than ones that only operate over wifi. This meant that we were able to send back data from our remote location without an additional Internet connection. The data speeds were very slow, and the cell towers were completely down for a full 24 hours at one point, but we were still able to send data from the devices to our servers.

We did, unfortunately, run into trouble trying to submit forms with photos attached. The data connection was too poor to transmit the photos, and the submissions timed out before they were sent. To solve this problem, we removed the photos from our survey, and took pictures using the camera app instead. We made sure the photos were geotagged, and we manually removed them from the devices instead.

GPS Accuracy
Generally Android devices and ODK Collect have trouble recording GPS points with less than 5 meter accuracy. Better quality readings are especially important for our soil research, so we recorded the same location three times within each survey. We have not yet determined whether that technique improved our results, but we will post here when we do.

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