Biomass Production Potential and Nutrient Dynamics of Populus deltoides under High Density Plantations

The experiment on Populus deltoides was laid out in randomised block design with three densities viz 60 cm x 60 cm (27,777 plants/ha), 90 cm x 90 cm (12,345 plants/ha) and 120 cm x 120 cm (6,944 plants/ha) under rainfed conditions in mid hill zone of Himachal Pradesh. The plantation harvested after 13 years, produced maximum biomass (218.08t/ha) in the closest spacing of 60 cm x 60 cm for which the bole contributed 90.71 per cent of the total above ground biomass accumulation. The nutrient accumulation in the biomass also differed with the density. The maximum nutrients were present in the closest spacing. It was further observed that organic carbon content in the soil decreases with the decrease in density. Conversely, an increase was observed in nitrogen, phosphorous and potassium content of soil with the increase in spacing. Study reveals that accumulation of nutrients in the biomass is higher in 60 cm x 60 cm spacing whereas, the nutrient return through litterfall was less as compared to the total uptake which created nutrient deficit in the soil.