Discoveries: Mr P K De investigating the effects of Blue-Green Algae on Nitrogen Fixation, 1938.
In 1938 Mr P.K De was sent to Queen Mary College by the Imperial Council of Agricultural Research, Delhi, to investigate the role of the blue-green algae in the process of nitrogen fixation in Indian rice-fields.
This investigation was a result of the observation that rice can be grown year after year successfully on the same land, with no manure. When the rice fields are water-logged, algae grows, and Dr De was investigating whether it is this algae that allows the constant growth of rice.
15g samples of soil from different areas of India were covered in distilled water. Some were kept in conditions in which the algae cannot grow, and some in conditions where it can. To keep samples in the correct light and temperature conditions, the apparatus pictured was designed and constructed in the College.
The cultures grown in the apparatus were investigated by chemical analysis and the fixation of nitrogen by the algae was conclusively proved. In May 1939, a paper detailing his discovery was published in Proceedings of the Royal Society, entitled ‘The role of Blue-Green Algae on the Fixation of Nitrogen Fixation in Rice-Fields’.