DRY-MATTER PRODUCTION AND NUTRIENT CYCLING IN AGROFORESTRY SYSTEMS OFCARDAMOM GROWN UNDER ALNUS AND NATURAL FOREST

A study on dry matter production and nutrient cycling in agroforestry systems of cardamom grown under N-2-fixing Alnus and mixed tree specie s (non-N-2-fixing) was carried out in the Sikkim Himalaya. The stand t otal biomass, and tiller number, basal area and biomass of cardamom cr op was much higher under the influence of Alnus. Annual net primary pr oductivity of Alnus trees was slightly higher than mixed tree species in spite of lower stand density of Alnus. The agronomic yield of carda mom increased by 2.2 times under the canopy of Alnus. Litter productio n and its disappearance rates were also higher in the Alnus-cardamom s tand. Nitrogen and phosphorus concentrations of different components o f Alnus were higher than those of mixed tree species, whereas their ba ck translocation from leaf before abscission was lower in Alnus. The c ardamom based agroforestry system under the influence of Alnus was mor e productive with faster rates of nutrient cycling. The poor nutrient conservation and low nutrient use efficiency of Alnus, and malleabilit y of nutrient cycling under its influence make it an excellent associa tion which promotes higher availability and faster cycling of nutrient s.