engleski

Soil C/N ratio after eleven years of differed nitrogen fertilization

Fertilization with different amounts of mineral nitrogen (0 do 300 kg N /ha) have been applied continuously, from 1996 till 2006, in a stationary field experiment established on drained Pseudogley in Central Croatia. Trial treatments included annual fertilization with different mineral nitrogen rates, respectively with 0, 100, 150, 200, 250 and 300 kg N/ha. Analyses of total nitrogen and total carbon content in soil are presented for three investigated depths (0-30 cm, 30-55 cm and 55-80 cm), for soil samples taken three times during 2006 (April, July and December). Total nitrogen and carbon content were determined by dry combustion method (according to Dumas ; HRN ISO 13878:2004 for nitrogen and according to HRN ISO 10694:2004 for carbon). First soil samples were taken at 12th of April 2006, before second top dressing of winter wheat, second sampling was just after the harvest (17. July) and third sampling was at 18th of December. Differences in total nitrogen and carbon content have been noted after eleven years of fertilization, according to nitrogen rates and soil depths. Average content of total nitrogen in soil surface layer (0-30 cm) varied from 4489 to 8648 kg N/ha, in subsurface layer (30-55 cm) from 2226 to 7541 kg N/ha and in the next soil layer (55-80 cm) from 1713 to 4790 kg N/ha. Total Carbon content in soil varied between 0.235 % and 1.955 % and C/N ratio ranged between 2.1 and 10.8 depending on the time of sampling, depth and treatment.

Total soil nitrogen; total soil carbon; nitrogen fertilization

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