EFFECT OF BED AND CONVENTIONAL PLANTING SYSTEM ON ORGANIC AND MICROBIAL BIO-MASS CARBON, ENZYME ACTIVITIES AND CARBON AND NITROGEN MINERALIZATION.

Soil organic carbon (C) level, microbial biomass C, dehydrogenase, phosphatase,
activities and C and nitrogen (N) mineralization were studied on well drained and poorly
drained soils in bed and conventional planting system of rice-wheat cropping sequence
in both well drained and poorly drained soil. Bed planting system had higher yield of
wheat and an increase in organic C was observed under bed planting system than
conventional in well drained (from 0.35 to 0.44%) than poorly drained soils (from 0.33
to 0.45%). Bed planting system had higher rate of C and N mineralization than
conventional planting system. In well drained soil, the mineralizable form of C and N
were 648 mg C and 62 mg N/ kg soil in bed and 603 mg C and 46 mg N/ kg soil in
conventional planting system, respectively. In poorly drained soil, the mineralizable form
of C and N were 576 mg C and 51 mg N/kg soil in bed and 454 mg C and 43 N/ kg soil in
conventional planting system, respectively. Bed planting system had more microbial
biomass C in both well drained (367 and 386 mg kg-1 soil in first year and second year,
respectively) and poorly drained soil (305 and 324 mg kg-1 soil in first year and second
year, respectively) than conventional planting system in well drained (319 and 322 mg
kg-1 soil in first year and second year, respectively) and poorly drained soil (289 and 292
mg kg-1 soil in first year and second year, respectively). Dehydrogenase and phosphatase
activities were also higher in bed planting system than conventional planting system in
both well drained and poorly drained soil.