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.