Page 60 - E-BOOK English

Profile features

Ferralsols are typically found at stable geomorphic surfaces.
The weathering of parent material is developed continuously and
for a long time, vertically affecting the soil profile. According to high
weathering, Ferralsols are deep and generally show yellowish or reddish
colours, uniformly profile features. Distinct horizonation is difficult to

characterize due to its uniformity of the accumulation of iron and
aluminum oxides, free oxides, including low activity clays. Aggregation
of soil particles is strong to very strong as influenced by oxides of iron
and aluminum together with clay minerals, thereby giving an excellent soil structure. With a stable
microstructure, these soils are very crumbly, resulting in high infiltration of the surface soil.

Environment and landforms

Ferralsols are typically found at perhumid or humid tropics where the moisture conditions
are sufficient with a consistent period to mediate chemical reactions rapidly. They generally occur
on stable geomorphic surfaces of Pleistocene age or older. Favorable topography can be flat to
undulating with minimal steepness or stable hilltop. Parent material is various and easy to be

weathered, including silica-rich granite and sediments, residual of basalt and gabbro (saprolite), or
colluvium derived from basic igneous rocks enriched with magnesium. Vegetation surroundings are
also diverse upon the difference in the current climate.

Use and management

Ferralsols have low fertility for growing plants, low cation exchange capacity, and weath-
erable minerals are scarce or absent. Oppositely, the physical properties of Ferralsols are suitable
for crop production due to their good structure with high infiltration capacity. These soils are
well-drained but may, at times, be easy to lose water rapidly because of their low available
holding capacity. The recommended practices for Ferralsols, therefore, include applications of
manure and compost fertilizers to improve fertility in combination with mulching to keep soil

moisture. Generally, the key problems of Ferralsols are of their fertility and fertilizer applications to
optimal crop yields. Determining the planting date of these soils is also critical to provide sufficient
moisture for plant growth. Most Ferralsols in Thailand are used for crop production such as
corn and cassava, as well as fruit trees such as mango, jackfruit, durian, and mangosteen. Dripping
irrigation is usually applied and yields good results. In the current agriculture, the rate and type of
fertilizer applications for these soils should follow as academically advised by relevant organizations.

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