Learning About Soil as a Natural Water Filter

In mid-August 2022, Begawan’s students commenced a new theme entitled Soil and Farming, a theme which will emphasise the significance of soil health, types of soil, functions of soil, soil erosion and conservation, organic and non-organic farming, the rice cycle, and regenerative farming. 

Introduce New Theme with Experiment

To introduce the theme, the students learned about different types of soil and soil layers. They knew that soil consists of different layers and each layer has different characteristics. At the end of the month, the students learned about the function of soil to purify water by conducting a science experiment.

Students worked in small groups, dividing the tasks among each group member so that their work would be more effective. Some students looked for rocks around the learning centre, other students made dirty water using a bottle of water mixed with dirt or potting soil. They also washed the rocks and sands in readiness for the experiment.

Start Experiment with Natural Water Filter

When all the materials were ready, each group sat in a circle and experimented. They arranged the materials to represent the composition of soil layers in nature. At the bottom they put cotton, which represents the pores of the soil layer, then large rocks, which represent the bedrock soil layer. After that, small pebbles represent the regolith layer. Above this, sand represented the subsoil, charcoal then represented the topsoil and organic matter, and the top layer was covered with tissue-like soil pores. After such an arrangement, the water filtration was ready for use. They slowly poured the dirty water into the water filter. All the students watched closely how the dirty water was filtered as it passed through the layers to become clearer water.

After finishing the experiment, students shared their observations with their friends. All groups noted that the colour of the water after the filter process had changed. Before the experiment, the water was dark brown, but after the filtering process, it became slightly transparent. The experiment demonstrated to students that one of the most important functions of soil is water filtration. To a great extent, here in Bali, we rely on this groundwater, that collects in natural spaces underground to supply us with our clean water. (Ketut Desy)