Soil, water and nutrient conservation in mountain farming systems: Case-study from the Sikkim Himalaya

The Khanikhola watershed in Sikkim is agrarian with about 50% area under ra in-fed agriculture representing the conditions of the middle mountains all over the Himalaya. The study was conducted to assess overland flow, soil lo ss and subsequent nutrient losses from different land uses in the watershed , and identify biotechnological inputs for management of mountain farming s ystems. Overland flow, soil and nutrient losses were very high from open ag ricultural (cropped) fields compared to other land uses, and more than 72% of nutrient losses were attributable to agriculture land use. Forests and l arge cardamom agroforestry conserved more soil compared to other land uses. interventions like cultivation of broom grass upon terrace risers, N-2-fix ing Albizia frees for maintenance of soil fertility and plantation of horti culture trees, have reduced the soil loss (by 22%). Soil and water conserva tion values (>80%) of both large cardamom and broom grass were higher compa red to other crops. Use of N-2-fixing Albizia tree in large cardamom agrofo restry and croplands contributed to soil fertility, and increased productiv ity and yield. Bio-composting of farm resources ensured increase in nutrien t availability specially phosphorus in cropped areas. Agricultural practice s in mountain areas should be strengthened with more agroforestry component s, and cash crops like large cardamom and broom grass in agroforestry provi de high economic return and are hydroecologically sustainable. (C) 2001 Aca demic Press.