Cxv. Studies on the Anaerobic Decom- Position of Plant Materials

IN a previous communication dealing with the anaerobic decomposition of rice straw [Acharya, 1935], it was noted that several factors such as temperature and reaction of medium greatly influenced the rate and course of the decomposition. An examination of some of these factors is reported in the present paper. The experimental procedure and methods of analysis adopted were the same as used previously [1935], except for the changes and modifications noted in the experiments described below. Exp. 1. Influence of temperature. To 20 g. portions of rice straw were added a mixture of 2 g. KHCO3 and 2 g. NH4HCO3 in order to neutralise the acids formed, 0-2 g. K2HPO4, 0*05 g. MgS04,7H20, 10 ml. of a 2 0% extract of a rice soil and water to make up 200 ml. The bottles were stoppered and paraffined and after evacuation were incubated at the desired temperatures. At weekly intervals the accumulated gaseous products were tapped off into a Hempel's burette, measured and samples taken for analysis. The liquid and solid residues in the bottles were analysed at the end of 6 months, according to the procedure already described. The data obtained, calculated per 100 g. straw taken, are given in Table I.