EFFECT OF AMENDMENTS, MOISTURE AND TEMPERATURE ON ACETYLENE-REDUCTION IN NILE DELTA SOILS

The pattern of N2-ase activity in clay-loam soil of Nile Delta was determined. However, unamended soil showed somewhat low activity: an amount of 18-95 mg N2 fixed/kg soil/year was calculated. Addition of glucose greatly enhanced such activity and efficiencies of N2-fixation increased with decreasing carbon source concentration. Highest activities (800 n moles C2H4/gh-1) and efficiencies (18.06 mg N2/g glucose added) were reported in soil amended with 1% glucose, adjusted to 50% W.H.C. and incubated at 30°C. Enrichment of the soil with straw lead to a significant nitrogen gain particularly under water-logged conditions. During a short period of 16 days 5.8-9.3 mg N2 were fixed/g straw added at the latter conditions. © 1979 Martinus Nijhoff, The Hague.