UNBURNT BUSH FALLOWS - A PRELIMINARY INVESTIGATION OF SOIL-CONDITIONSIN A BUSH FALLOW AND 2 SUCCESSIVE CROPS OF TARO (COLOCASIA-ESCULENTA (L) SCHOTT) IN WESTERN-SAMOA

Little research has examined shifting cultivation systems that do not burn their bush fallows. This work examines three phases of shifting c ultivation (mature bush fallow and the first and second successive tar e crops) on five inceptisols (Falealili, Tiavi, Etimuli, A'ana and Ave le) in Western Samoa during May 1990. Traditional farming practice was used on ah sites, including not burning the bush fallows after they w ere cut down. The soil bulk density increased with the phases of shift ing cultivation on the Falealili soil. The soil water content at both field capacity and wilting point and the available water capacity incr eased with the incorporation of the bush fallow, and then decreased wi th cropping. The flush of nutrients following the bush fallow was smal l, and included increases in potassium on the Tiavi soil, calcium on t he Etimuli and A'ana soils, magnesium and total exchangeable base cont ent on the Tiavi and Etimuli soils, manganese on the Avele soil and zi nc on the Etimuli soil. There were also decreases in soil phosphorus o n the Tiavi and Avele soils. Changes in tare nutrient concentration wi th cropping included decreases in foliar nitrogen on the Falealili soi l and sodium on the A'ana soil, and increases in foliar magnesium on t he Etimuli and A'ana soils. More long-term research is needed on shift ing cultivation systems that do not burn their bush fallows.