Abstract

Mussoorie Phos (MP), an indigenous rock phosphate used as a fertilizer, contains phosphorus and calcium as major constituents and magnesium, iron, sulphur, potassium, zinc, molybdenum and copper as minor constituents. It was added at dosages of 0, 2550, 75 or 100 g/kg of soil to strongly to medium acidic surface soils (0-20 cm) taken from 4 eucalypt plantations in Kerala. One-month-old eucalypt seedlings were grown on 1 kg soil in plastic pots for 19 wk. A further experiment was conducted on a medium acidic surface soil in concrete pots 35 cm tall and of 25 cm diameter with 0, 50, 100, 150 or 200 g/pot MP added at 10, 20, or 30 cm depths. Three-month-old eucalypt seedlings raised in polypots were planted in the concrete pots at 20 cm depth and shoots and roots harvested after 19 wk. A pilot field trial was also run on a medium acidic soil with 0, 100 or 200 g MP added per seedling; sapling height and girth at 30 cm were measured after 20 months. The pot trial on strongly to medium acidic soil showed good response to MP inputs. The concrete pot experiment on the medium acidic soil showed that 150 g MP placed at 20 cm depth had the best effect on root growth of seedlings. The pilot field trial on the medium acidic soil showed a significant increasein girth of saplings with the addition of 100 g MP/seedling. It is, therefore, recommended that 100-150 g MP is applied to the planting pit for eucalypts at 10-20 cm depth and 10 cm away from the seedling