Abstract
Microbial biomass N was measured in 18 agricultural soils collected from Punjab, Pakistan using a chloroform fumigation extraction method (CFEM), a chloroform extraction method (CEM), and a chloroform fumigation-incubation method (CFIM) using anaerobic incubation. In CFEM, the soil samples were exposed to chloroform vapour for 24 h followed by estimation of the K2SO4-extractable N whereas in CEM, soil samples were directly extracted with K2SO4 containing 10% chloroform. In the CFIM, fumigated and unfumigated samples were incubated for 15 days under anaerobic conditions and the NH4-N accumulated in the soils was used to calculate biomass N.
The biomass N determined by CEM accounted for 2.8 to 13.8% of the total soil N; the average value for all soils was 6.9%, an almost similar variation (2.6 to 14.8%) was observed for the CFEM. The biomass N determined by the two methods was highly correlated (r=0.89,P<0.01). Biomass N estimated by CFIM in soils incubated under anaerobic conditions accounted for 6.1 to 13.6% of the total soil N but showed no significant correlation with biomass N determined by either CFEM or CEM.
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Azam, F., Yousaf, M., Hussain, F. et al. Determination of biomass N in some agricultural soils of Punjab, Pakistan. Plant Soil 113, 223–228 (1989). https://doi.org/10.1007/BF02280184
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DOI: https://doi.org/10.1007/BF02280184