Mother tending her children

Installing the last sensor in Mokwakwaila

During November 2013 we also installed a third sensor station in Mokwakwaila. The station has two soil moisture sensors on two different depths.

We got the opportunity to install the sensor at the school. The principal kindly accepted us, even though it was exam period when the learners should have piece finalizing their tests.

The sensor is comparatively close to the first sensor we installed at the site. The first sensor, however, was installed in the (maize) field, whereas this is on the school's ground.

Examples on measured data

Just to give an update on what the sensors report. In Mokwakwaila I downloaded the temperature information and the data from the rain gauge, as well as the soil moisture sensors. The data of these sensors are sampled once each day.

In the figure below we see the measured rain fall (yellow) and the shallow and deep soil moisture sensor (blue and red, respectively). The rain gauge gives us the instantaneous value (well, integrated over one day), and the soil moisture sensors show how much is stored in the ground. We see that the shallow sensor reacts within the same day, whereas the deeper one (also larger volume) reacts later. This illustrates how slowly the moisture penetrates the ground and how quickly it evaporates from the upper layer. On the last of October, Mokwakwaila received 43 mm of rain. We can also see from the data how the soil moisture increases slightly before arrival of the large rain quantities. This is partly due to the small amounts of rain that occurs the weeks before the last of October.

Below we show the measured soil temperature out in one of the fields. The first measurements started in June and indicated some 20 degrees. Since then, the average temperature has increased some 6 degrees. We see that the variations are quite big within a few days.

Installing more sensors in Lambani

Earlier this week, we installed more sensors at on of the sites. We were kindly invited by one of the high schools to have one of the stations installed there. The station contains a logger, and three soil moisture sensors.

We got help digging from some of the learners and staff at the school. Ashley, far on the left, is from the LDA office in Polokwane.

The trip continued up-hill for the installation of the third sensor station. This time in the field. It was a warm day...