Nutrient Cycling in Eucalyptus globulus Plantation III-nutrients Retained, Returned Uptake and Nutrient Cycling

Biomass, productivity and nutrient cycling In a Eucalyptus globulus plantation of age 10 years (density 1575) trees/ha) was studied. The total above-ground biomass produced was 76877 kg/ha of which wood contributed 50456 kg/ha and the rest by other components. Roots contributed 18% of above-ground biomass. Chemical analysis revealed that, on an annual basis, out of the 43 kg/ha of N,2.8 kg/ha of P and 36 kg/ha of K retained in the biomass, 19, 1.5,19 kg/ha of N, P and K respectively was accumulated in wood. Thus maximum drain of nutrients occurs through wood harvest and among the nutrients the highest drain occurs for N and K. Litter production in the plantation amounted to 8492 kg/ha, of which leaf litter contributed 3402 kg/ha, twig 3187 kg/ha and bark 1903 kg/ha. With regards to the nutrients return N amounted to 58 kg/ha; P, 4.0 kg/ha and K, 40 kg/ha and leaf litter contributed maximum amount of all nutrients. These results have been compared with other plantation species like E. hybrid, E. grandis, Dolbergia sissoo and Pinus palula . The article also points out the significance of biomass components harvest over complete tree harvest.