Studies on composts prepared from waste materials III Nitrification in Soil

1. The mean proportion of nitrogen in 23 samples (representing 18 different composts) that nitrified in soil in 5 and 13 weeks was found to be 9.3 and 10.6% of the total nitrogen; this difference was not statistically significant. 2. The amount of nitrogen in composts that nitrified in soil in 5 and 13 weeks correlated significantly with the amount of organic plus inorganic nitrogen in the composts that was soluble in cold O.IN‐hydrochloric acid. 3. The percentage of the total nitrogen that nitrified in soil in 13 weeks was closely correlated with the nitrogen content of the organic matter in the compost for composts prepared from similar materials (sewage sludge and straw). There was no similar correlation, however, for composts from different materials (sewage sludge and town's refuse, coir fibre, cotton‐waste, etc.)