Abstract:
A factorial combination of saline and non-saline soil with three residue types (Sesbania grandiflora, Caliandra calothyrsus and Gliricidia
maculata leaves) was used in laboratory incubation. The CO2-C content of plant residue amended soils was found to be increased steadily
during the first two weeks of incubation followed by gradual reduction as incubation progressed. Under non-saline condition (EC=0.97
dS/m), the highest cumulative CO2-C content (1551 mg/kg soil) was observed in Caliandra amended soil, followed by Sesbania (1161
mg/kg soil) and Gliricidia (1042 mg/kg soil). The higher biodegradability of Caliandra leaves induced by the higher C content compared
to the other residues. The CO2-C evolved under saline condition (EC=18.2 dS/m), ranged from 313 mg/kg (control) to 905 CO2-C mg/kg
(Caliandra amended) soils. Sesbania amended non-saline soil showed the highest (227 mg/kg soil) and rapid release of NH4
+
-N, followed
by Gliricidia (181 mg/kg soil) and Caliandra (177 mg/kg soil). Whereas under saline condition, release of NH4
+
-N ranged from 93 mg/kg
(control) to 183 mg/kg (Sesbania amended). Though treatment behavior pattern of NO3
- -N was similar to that of NH4
+
-N throughout the
incubation, saline soil showed significantly (P< 0.05) low NH4
+
-N and NO3
- -N contents compared to non-saline soil.
