Biomass productivity and influence of intercrops in a pre-bearing coconut-casuarina agroforestry system

Abstract

An experiment was conducted in the pre-bearing coconut gardens of Agricultural Research Station, Mannuthy during the period from May 1987 to May 1988 to assess the biomass productivity of different intercrops grown in coconut - casuarina alleys and their effect on the growth of tree components and on the micro-meteorological parameters. The different cropping systems tried in coconut casuarina alleys were tapioca + groundnut, amorphophallus - horsegram, fodder maize + cowpea - fodder cowpea, guinea- grass' (throughout), fodder cowpea - sesamum, groundnut blackgram, modan paddy - sesamum- and control (without any intercrops). The experiment was laid out in randomised block design in plots of size 7.5 x 7.5 m and replicated thrice. The plant height of all the crops excepting thatof fodder cowpea and sesamum showed an increase when grown I; in coconut - casuarina alleys. The yields of tapioca,', groundnut (grown mixed with tapioca), amorpho phallus, blackgram and paddy were rather low in coconut - casuarina alleys compared to sole crop yields. Fairly high fodder yields of maize (mixed with cowpea) and guineagrasswere obtained when grown in coconut - casuarina alleys. Regarding the total biomass production of different cropping systems, amorphophallus - horsegram cropping system recorded the highest and groundnut - blackgram cropping system yielded the lowest. The soil physical properties like bulk density, particle density, maximum water holding capacity were not influenced by the different cropping systems. It was seen that most of the cropping systems except that involving guineagrass left the soil richer with respect to organic carbon content and most of the primary and secondary nutrients. The cropping system which recorded fairly high gross income, net income and benefit-cost ratios were amorphophallus - horsegram, fodder maize + cowpea - fodder cowpea and groundnut - blackgram. The different component crops grown in the alleys had no adverse effect on coconut or casuarina. Casuarina which was intercropped with coconut was found to be capable of generating a fuel wood yield of 10-11 t/ha/annum.