Abstract:
Available nitrogen was determined using 11 extractants on 29 soils covering a wide range of physical and chemical properties. Assessment of 2M KCI (p H 7.0), IN NaCI, IN NaCI (pH 1.0), 2N NaCI, IN Na2S04 ( p H l .O ) , 0.5N NaHCOa ( pH 8.5 ), Morgan’s reagent, O.IN C a C h , 0.5N HCl, 0.7N HCI and 0.5N H2SO4 extractable nitrogen showed that the best efficiency was obtained by IN NaCI. IN NaCI and 2M KCI extractable nitrogen bear significant relationship with soil organic matter and total nitrogen were found to be dependent on the type of soil. Correlation study with nitrogen uptake by BR-4 rice reveals that 2M KCI is superior to IN NaCI and closely followed by IN NaCI. Compared to these two extractants both aerobic and anaerobic incubation methods produced less satisfactory results.
