Cheap and portable lab-free respiration assay

A simple tool that can be set up just using agarose, cotton wool, a plastic test tube and a pH indicator are presented as a method to measure soil respiration and record its kinetics in time. The principle is based on the fact that CO2 produced by respiration dissolves in the water of the gel and acts as an acid, lowering the pH in proportion to its intensity. Both basal and substrate-induced respiration can be measured and compared by wetting the soil with either water or glucose solution. The assay is done with 3 g of air dried soil and only requires a daily visual inspection of the progressively changing color of the agarose gel in the tube. It is also amenable to measures to be followed away from the lab (at home, in the field, during expeditions, exploratory campaigns etc.). The low cost and versatility of the principle allows to carry out environmental research monitoring in any country irrespective of laboratory facilities or complex supplies. The result is proportional to soil vitality, fertility and overall attitude to be responding to stimuli or to indicate pollution and overall impacts affecting its properties. Examples of respiration in organic farms soils vs. conventionally managed ones are shown.