A qualitative experiment to analyze microbial activity in topsoil using paper and a handmade reflection photometer

A unit on the qualitative analysis was developed for the microbial activities in topsoil by using a copy paper and a handmade cadmium sulfide-light emitting diode (CdS-LED) reflection photometer where the principles of combining complementary colors were applied. In different soil samples, microbial activity increased as the exposure time increases. It was found out that there were microorganisms in all the soils and that the microbial activity in the garden soil is more pronounced relative to the other soil type. This experiment will certainly give students a better understanding of the presence and significant contribution of the biological activities of soil microorganisms.