Abstract
To explore the effective countermeasures against the simultaneous degradation, i.e. soil erosion and loss of bases, of land resources in northeast Thailand, we tested the performance an agro-forestry system at Yang Khi Nok Village, Khuangnai District, Ubon Ratchathani Province. Establishment of agro-forestry system aims at a sustainable management of both cropland and forest.
Pineapple (Ananas eomosus (L.) Merr) and kenai (Thai kenai, H sabdariffa L. var. altissma) were cultivated as cash crop and three rows of fruit tree (psidium guajava, Cocos nucifera, Pithecollobium dulce, Punica granitum, Tamarindus indica, and Zizyphus jujuba) were placed among the cash crop rows. Erosion control belt (8 treatments) composed of 3 trees (Phyllanthus acidus, Eucalyptus camaldulensis, and Azadirachta indica), 3 grasses (Vetiveria nemoralis, Cymbopogon citratus, and Sporobus virginicus), rice straw mulching, and control was introduced at the lower end of the subplot. A small catchment was also installed to collect the eroded soil.
Soils in this plot has sandy soil texture with a high erodibility. Soil erosion at the current work was not so severe in all treatments. It was suggested that fruit tree planting area prevented soil erosion because this area was not plowed. Tree treatment plots in the erosion control belt, however, showed a greater soil erosion and a loss of bases, compared with others. This was attributed to an insufficient weed growth to cover the ground surface and low soil moisture content at the erosion control belt in the tree treatment plots. However the mass of eroded soils even in the Eucalyptus plot gradually decreased during the succeeding years (1997-2000) presumably due to tree crown and/or litter coverage on ground surface. Thus it can be considered that, in terms of erosion control, grass species is better but tree species can also have considerable potential for utilization in the long run.
