Abstract

This project was undertaken to study the effect of various silvicultural treatments and nutrient combination on the growth and volume of eucalypts and to evaluate the nutrient uptake and partitioning in different parts of the plant. Experimental plots were laid out in the grasslands at Vallakkadavu and seedling of Eucalyptus grandis planted over an area of 80 ha. Nine silvicultural treatment viz three pit sizes, three spacings and three skinning operations of line, complete and around the plant and 16 nutrient combination of Nitrogen (N), Phosphorus (P) and Potassium (K) were tried. Fertilisers with four levels viz 0, 15, 30 and 40 g/plant of each of the nutrients were added initially in the pit before planting (June), during north- east monsoon (October) in the first year and south-west monsoon (June) in the second year with double the doses of that applied during the first year. Height was measured at three months intervals during the first year and at six months interval thereafter upto three years. Girth at breast height (gbh) was recorded at the end of 36 months of planting and the volume of trees estimated using prediction equation. Another experiment with high density planting was also conducted employing the same 16 nutrient combinations in three pit sizes. It was found that there was significant difference in height of E.grandis trees due to various silvicultural treatments and nutrient combinations. Among the various silvicultural treatments, 3 m X 3 m spacing, 20 cm X 20 cm X 20 cm pit size and line skinned treatment was found to be the best in terms of volume. The study on the nutrient accumulation at different parts of the trees revealed that the amount of nutrients in bolewood was twice of that in branches and one and half times of that in leaves. The multilocational trails showed that the best set of silvicultural treatments and nutrient combinations for E.grandis were equally matching for E.tereticornis at lower elevations