Effects of ecological agriculture on soil properties and arthropod diversity in rice-based cropping systems in floodplain areas in Bangladesh

Rice farming is practised on 75% of the arable area in Bangladesh and is crucial to the ability of the country to feed its growing population and to enhance the livelihoods of resource-poor farmers. Currently, there are concerns about the sustainability of intensive production systems that are based on inorganic fertilizers and pesticides. This paper describes recent field research conducted by PROSHIKA, a non-government organization promoting ecological farming, and its collaborative partners at two locations in Bangladesh. Ecological farming is compared with conventional rice farming systems with regard to the effects on soil properties and arthropod communities. In 1997, soils were analysed for macro and micronutrients, organic matter content and physical properties. At each location, soil bulk densities were significantly lower (p < 0.05) in fields under ecological farming than in those under conventional management. Fields under ecological farming had higher levels of exchangeable calcium than conventional fields and at one location, Koitta, the cation exchange capacity was also greater. At Koitta, soil organic matter fractions were greater in ecological than in conventional fields. Arthropod densities were low at both locations in the 1999 boro season. Ecological fields at Koitta supported more arthropods than the conventional fields, whereas at Gabtoli the arthropod load in ecological and conventional fields was similar. The relative abundance of plant-feeding insects and natural enemies was similar in ecological and conventional sites at each location. There was no consistent significant difference between the mean grain yields in the conventional fields and in the ecological fields. Taking into account the environmental and health benefits of ecological farming, there is considerable potential to maximize the use of organic material and to reduce unnecessary pesticide usage in rice production in Bangladesh.