The Soils of the Lowlands

Abstract

The lowland soils represent the heavy use of our land resources being easily accessible to the general populace. These are the flat areas located between the sea and the surrounding uplands, hills, and mountains. The alluvial flood plains, being dissected by a meandering river, are regularly visited by floods. Yet, great civilizations of East and West both of the past and of the present were built on river banks because of the agriculturally productive soils and the ease of navigation and transport even to the hinterlands. These are the best areas for agriculture since the farms are annually renewed by the silt that comes with the flood when the monsoon season comes. Ironically these days, because of the pressure of population increase and urban expansion, agriculture finds itself eased out as it competes with residential, commercial, industrial, and recreational land uses. As the farms give way to the residential subdivisions and industrial estates, the centuries-old traditional Filipino houses, slightly raised above grounds and standing on stilts, are abandoned in the quest for more living space. When the annual floods come, the social, economic, and environmental costs are staggering. We also greatly invest on flood protection infrastructures that address more the effects rather than the causes of floods. Understanding our lowland soil resources incorporates a holistic perspective in the development planning process. This chapter dissects the lowland soils into its geographic setting for land management purposes—(1) soils of the coastal areas, (2) soils of the river and lake terraces, and freshwater swamps, (3) soils of the narrow and broad alluvial valleys and flood plains, and (4) soils of the infilled localized valleys, collo-alluvial plains, and fan terraces. These soils are developed from alluvial deposits, with slopes ranging from 0 to 8 %, altitude of less than 100 m above sea level, and temperature of more than 25 °C. This chapter includes unpublished but recognized soil series through more recent mapping projects or past soil surveys with missing reports even in the archives.