  We discuss the history and lessons learned from a series of deployments of
environmental sensors measuring soil parameters and CO2 fluxes over the last
fifteen years, in an outdoor environment. We present the hardware and software
architecture of our current Gen-3 system, and then discuss how we are
simplifying the user facing part of the software, to make it easier and
friendlier for the environmental scientist to be in full control of the system.
Finally, we describe the current effort to build a large-scale Gen-4 sensing
platform consisting of hundreds of nodes to track the environmental parameters
for urban green spaces in Baltimore, Maryland.
