Bioavailability of Nitrogen Derived from Jatropha Curcas L. Seed Cake through an Incubation Study

Organic matters and waste products are used as nitrogen fertilizer in the urban and peri-urban agricultural plant production in Kinshasa city, Democratic Republic of Congo. Jatropha curcas L. (JCL) seed cake was mixed thoroughly with CREN-K soil(96%sand) and incubated for 1, 3, 7, 14, 21 and 42 days in glass flask under controlled conditions (28°C and 20% of moisture content). At the end of each incubation period, mineral nitrogen was extracted by adding 1N KCl (ratio KCl: soil 1:2). NH4 +-N content was higher than NO3 --N content at all incubation periods and reached a maximum value of 173.95 mg N/Kg of soil. Net inorganic N (NH4 +-N+NO3 --N) released was relatively rapid during the first 14 days- of incubation.Rich in nitrogen (5. 67%),JCL seed cake has a potential to be utilized for soil fertility improvement and can be used as bio-fertilizer for short vegetative cycle of market gardening’s.