A comparative study of time of application between humic acid and organic matter on N transformation in soil

Department of Agricultural Chemistry and Soil Science, Bidhan Chandra Krishi Viswavidyalaya, Mohanpur, Nadia-741 252, West Bengal, India E-mail : ashimdatta2007@gmail.com Manuscript received 27 December 2012, revised 22 August 2013, accepted 12 September 2013 A laboratory investigation was carried out to monitor changes in different forms of N in soil treated with humic acid or organic matter 21 days before or on the day of start of the experiment. Results reveal that irrespective of treatments and stages of incubation, comparatively higher amount of exchangeable NH4+ and soluble NO3– is accumulated in soil treated either with FYM (Farm Yard Manure) or humic acid 21 days before than on the day of start of the experiment. Humic acid is decomposed faster than FYM leading to higher amount of accumulation of available N in humic acid treated system. Again, in general, irrespective of treatments, hydrolysable NH4+ increased over 120 days period of incubation and the amount of increase is more in soil treated either with FYM or humic acid on the day of start of the experiment. Amino acid and total hydrolysable organic N are more prone to N-mineralisation