Effect of clump density/spacing on the productivity and nutrient uptake in Bambusa pallida and the changes in soil properties

Abstract

A trial was conducted on Bambusa pallida Munro. with three densities (278, 204 and 156 clumps/ha) of planting in square geometry over a period of 12.5 years. Planting density significantly influenced the circumference of clumps and the characteristics of culms i. e., number of internodes, mean height, girth, tapering rate, hollowness and dry weight of a culm. Total biomass productivity decreased from 341 t/ha at 278 clumps/ha to 234 t/ha at 156 clumps/ha. Accumulation of nutrients (N, P, K, Ca, Mg, Cu, Zn, Mn and Fe) in the above ground biomass followed the same trend. Total nutrient accumulation was 5 t/ha at 278 clumps/ha at the highest biomass producing density of 278 clumps/ha. Harvested culms drained nutrients from the plantation site to the tune of 469 kg/ha per year over the last six years, while floor litters enriched the plantation site by adding 79 kg nutrient/ha per year during last 10 years of study. Floor litters returned 15, 21 and 31% of the total nutrient uptake to the surface soil at the planting densities of 278, 204 and 156 clumps/ha, respectively. Mn and Fe accumulated by the bamboo biomass in the acid soil condition were largely (61–73%) returned through floor litters to the soil. In general, there was positive nutrient balance under three densities of planting. Under the bamboo plantation, surface soil (0–20 cm) electrical conductivity and soil pH improved and the soil was enriched with organic matter, Ca, Mg and Zn, but it was depleted in available P, exchangeable K and Fe in proportion to the density of clumps.