Estimation of shoot and root biomass with their C, N, P, K and S contents of eight different rice varieties at harvesting stage

Abstract

Hybrid hira, Hybrid tia, BRRI dhan28, BRRI dhan29, Binadhan-5, Binadhan-7, Laphadhan and Pijamdhan were grown in a medium high land soil (silt loam, aeric heplaquept) during boro season (crop period: January to June 2011). Shoot and root biomass and their C, N, P, K and S contents at full maturity were determined to assess their potentiality for using as organic residues for the maintenance of soil organic matter. The experiment was laid out in a Randomized Completely Block Design (RCBD) with three replications for each of eight rice varieties having unit plot size 4m×2.5m. Air dry shoot biomass obtained for Hybrid hira, Hybrid tia, BRRI dhan28, BRRI dhan29, Binadhan-5, Binadhan-7, Laphadhan and Pijamdhan were 5.28, 4.82, 4.10, 4.29, 4.98, 3.97, 3.69 and 4.28 t ha^-1 respectively and root biomass were 1.20, 0.91, 0.99, 1.11, 1.33, 0.78, 0.76 and 0.90 t ha^-1, respectively. Organic carbon content in the shoots were 2.97, 2.43, 2.44, 2.54, 2.72, 2.10, 2.04 and 2.73 t ha^-1, respectively and roots were 0.52, 0.46, 0.49, 0.51, 0.61, 0.38, 0.40 and 0.41t ha^-1 respectively. The C-N ratios for the shoots were found to be 150.6, 170.3, 361.0, 268.9, 192.8, 246.8, 203.4 and 315.2; and for the roots were 112.8, 89.7, 114.2, 68.7, 89.4, 108.6, 187.8 and 73.6, respectively. The PKS contents in both shoots and roots also estimate. It may be inferred that both shoot and root residues may play a significant role in organic manuring. Particular attention should be given for assessing the contribution of the root biomass.