NITROGEN TRANSFORMATION DURING THE ROTTING PROCESS OF RICE STRAW COMPOST

概要

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To evaluate nitrogen transformation during the rotting process of rice straw compost, a compost pile was prepared outdoors using rice straw, calcium cyanamide and waste soybeans. Samples for nitrogen analysis were taken from the pile after 2,3 and 5 months. After air-drying or incubating the wet samples with inorganic nitrogen compounds such as ammonium sulfate or potassium nitrate for 4 weeks at 30℃, levels of the inorganic forms of nitrogen were determined. A two-month-old sample showed considerable loss of ammonium after this treatment, and samples taken from the top layers of the 3- and 5-month-old compost and from the middle layer of the 5-month-old compost clearly showed nitrification. Both denitrification and nitrification processes were shown to be taking place in the samples taken from the middle layer of the 3-month-old compost and those from the bottom layers of the 3- and 5-month-old compost. From the results obtained here, the following conclusion was drawn : Nitrogen transformation during the rotting process of rice straw compost involved ammonification followed by the simultaneous occurrence of nitrification and denitrification, and finally, nitrification. Moreover, certain levels of ammonium and nitrate nitrogen were given which may be used as an index in determining the maturity of the compost.
社団法人日本土壌肥料学会の論文