Studies on Humus of Tea Soil (Part 3)

Decomposition of Organic Matter at Various Nitrogen Manuring Levels

Abstract

The decomposition of organic matter in tea soil at various levels of nitrogen (0, 10, 20kg./1000kg. organic matter) manuring was examined during 144 days.
Six organic matters were used in this experiment: Rice straw, tea leaf (old leaf), Japanese pampa grass, (Miscanthus sinensis), "Tenporon" (soil conditioner of peat) and. "Telnite" (soil conditioner: lignite was trea-ted with nitric acid).
Carbon dioxide evolution derived from the decomposition of organic matter was measured at 10, 20, 40, 80 and 144 days after the incubation.
The addition of nitrogen increased the decomposition of rice straw, tea leaf and Japanese pampa grass.
The amount of carbon dioxide evolved from the decomposition of sawdust, "Tenpo-ron" and "Telnite" in the nitrogen absence plots was much more than in the nitrogen added plots, and the evolved carbondioxide of the latter plots was about half the amount of that of nitrogen additional plots of rice straw, tea leaf and Japanese pampa grass.
Nitrogen requirement for the decomposition of these organic matters in tea soil was examined.
The amount of immobilized inorganic nitrogen was most after 40 days from incubation, and that of rice straw, tea leaf, Japanese pampa grass and sawdust was 7.5-17 kg. per 1000 kg. dry organic matter.
Immobilized inorganic nitrogen by "Tenpo-ron" after 40 days from incubation was 0.85 kg. per 1000 kg. dry matter, and "Telnite" did not require inorganic nitrogen.