Soil and nutrient losses from different land uses and vegetative methods for their control on hilly terrain of South Andaman.

Abstract

A study was conducted during 2003-05 to find out suitable vegetative methods of arresting soil loss from different land uses in South Andaman islands. The study reports soil and nutrient loss due to water erosion from 5 major land uses, i e vegetable fields, coconut plantation, arecanut plantation, home garden and moist evergreen forest on the undulating topography of the island. Soil loss under the land uses was quantified using replicated runoff plots for 2003-05. Vegetative methods, i e Gliricidia hedgerow+crop, hedgerow+mulch+crop, hedgerow+mulch+crop+grass barrier, for vegetable field under till conditions, and Pueraria cover crop (coconut+Pueraria phaseoloides cover crop) for coconut (Cocos nucifera L.) plantation were tested to know their potential to arrest soil erosion in the respective system. Soil loss from the vegetable field under no till conditions, coconut plantation, arecanut plantation, home garden and forest was 3.8, 12.4, 10.6, 8.4 and 2.3 tonnes/ha, respectively. Soil working in vegetable fields (till+crop treatment) made soil loss of 124 tonnes/ha. Erodibility was the lowest (0.06) in the forest and highest (0.26) in the vegetable field under till condition. Among the nutrients, the highest loss, across the treatments, occurred for nitrogen and lowest for phosphorus. The hedgerow alone in vegetable fields reduced the soil loss substantially (66%). However, it together with mulch and grass barrier reduced the soil loss nearly equal to that found in the forest. Likewise, Pueraria cover crop (19 years old) brought down the soil loss under the coconut plantation equal to that in the forest. These observations suggest that Gliricidia hedgerows for vegetable cultivation and cover crop for coconut plantation may be good vegetative methods for soil erosion control in the island.