LITTER FALL, NUTRIENT RETURN AND SOIL FERTILITY UNDER GREWIA OPTIVA: AN INDIGENOUS AGROFORESTRY TREE SPECIES IN HIMACHAL PRADESH

摘要

A study was conducted to assess litter fall, nutrient return and soil fertility under Grewia optiva which is an important agroforestry species in Himachal Pradesh. The average annual litter fall of 6. optiva has been recorded as 170.25 g/m~2/yr. The annual leaf litter recorded (79.56 g/m~2/yr which was 46.73 per cent of total litter) was maximum followed by miscellaneous litter (43.31 g/m~2/yr which was 25.44 per cent of total litter fall), reproductive litter (26.05 g/m~2/yr which was 15.30 per cent oftotal litter fall), twigs (17.83 g/m~2/yr which was 10.47 per cent of total litter fall) and the least was from bark component (3.50 g/m~2/yr which was 2.06 per cent of total litter fall). Nitrogen in leaf litter, twigs, reproductive litter, miscellaneous litter and bark was 2.23, 1.21, 0.91, 1.01 and 0.95 per cent respectively while phosphorus concentration was maximum (0.139 %) in leaf litter followed by twigs (0.11 %), reproductive litter (0.11 %), bark (0.11 %) and the least was in miscellaneous litter (0.08 %). Potassium concentration was varied from 1.13 per cent in miscellaneous litter to 2.03 per cent in leaf litter. Calcium concentration varied from 1.75 per cent in reproductive litter to 3.12 per cent in bark while magnesium concentration varied from 0.22 per cent in miscellaneous litter to 0.48 per cent in twigs. The trend of nutrient return was in order of Ca (4.26 g/m~2/yr) > K (2.71 g/m~2/yr) > N (2.48 g/m~2/yr) > Mg (0.72 g/m~2/yr) > P (0.18 g/mVyr). Monthly leaf litter and their respective nutrient concentration for nitrogen, phosphorus, calcium and magnesium were significantly related. Soils under G. optiva were well enriched in organic matter and available nitrogen, phosphorus and exchangeable potassium.