Influence of Human Activity on Water and Soil Conditions of Agricultural Land in Laos

Abstract

The central and southern regions of Laos are the more intensively cultivated areas than the northern and eastern regions of the country, consists of fairly high altitude mountainous. This chapter focuses on the influence of human activities on cultivated area in Laos and evaluates traditional agricultural practices with a view towards long-term sustainability. In case of Paksuun Village, where various land use change patterns can be readily observed, we found that changes due to swidden agriculture, or land use changes from secondary forest to plantation forest, did not appear to change soil physical properties. That is, soil property changes resulting from those land use variations are reversible. On the other hand, it was found that a change from secondary forest to paddy field, and then to pasture, might result in irreversible soil property changes, especially in soil density. For traditional rice production in rain-fed paddy field, the examples in Dong Khuai Village were introduced from viewpoints of surface water quality and effect of termite mounds. Through an investigation into various factors impacting the rice production, we found that the application of chemical fertilizer was not always effective for increasing rice yields in rain-fed paddy fields. Other factors such as water flow or floodwater cover as natural phenomena could be important controlling factors for rice yields. From our study, it was suggested that termite mounds could provide useful sources of fertilizer. From the viewpoints of land use change and the qualities of water and soils, we concluded that the present circumstances related to agricultural fields in the central regions of Laos, where traditional agricultural practice remain, would provide a sustainable method of food production.