Discussion on Sustainability of Arid Land Afforestation with Hardpan Blasting from Soil Chemical Assessment
Japan Society of Hydrology and Water Resources
Computing, Health and Science
School of Natural Sciences
The establishment of technologies for carbon fixation by large-scale afforestation on arid lands is required. Afforestation has been tested at a pastureland near Leonora, Western Australia where hardpan blasting and bank construction were conducted for effectively use of limited rainfall in the arid area. In the present paper, the change of salt provision and accumulation by the change of water movement has been focused. Salt accumulation tendency was checked by chemical assessment of soils and waters of rainfall, surface runoff water and irrigation water in the afforestation trial site. Both of electrical conductivity and concentrations of water-soluble ions of the soils in the area surrounded by the bank were higher than those at the outside of the area, which indicates that salt accumulation was slowly and gradually proceeding, although the salt damage has not become evident yet five years after the start of the afforestation trial. The source of each chemical element measured was identified. Na, Ca and Mg were mainly supplied from irrigation, and therefore, their accumulation is expected not to proceed any longer because irrigation was stopped. On the other hand, the source of K and P that are essential elements of plants was found to be rain water. It cleared that the soil concentrations of K and P under tree were higher than that of bare soil, and it estimated that K and P are returned into soil from litters and stemflow of plants.