Page 46 - Soil Degradation, Conservation and Remediation

1.7 Soil Degradation 31

Fig. 1.6 Brickfields in agricultural land (Photo courtesy of Dr. Animesh Biswas)

1.7.1.4 Soil Desurfacing

Soil desurfacing refers to the removal of a layer of surface soil for many different
purposes, including construction of road and railroads and making of bricks. Brick

is an important element of urban development. Most brickfields are located in fertile
alluvial lands for the presence of soils of suitable textures. For example, hundreds
of brickfi elds are seen in agricultural lands along both sides of the river Buriganga
near Dhaka, Bangladesh (Fig. 1.6 ). A more or less a uniform layer of soil, 15–20 cm

thick, is collected from the surface of huge areas of paddy fields. An estimate shows
that a five-story building of 250 m floor space needs 500,000 bricks. More than

2

1 ha furrow slice surface soil (100 m × 100 m × 15 cm) would be needed to make this
number of bricks. The surface soil is the most fertile part of the soil; it contains the
highest organic matter and nutrients and possesses the most suitable physical and
chemical conditions for plant growth. Soil desurfacing decreases organic matter,
nutrients, and available water, and the exposed subsoil is more compact. Soil desur-
facing significantly reduces soil quality and crop yields (Grewal and Kuhad 2002 ).

1.7.1.5 Monocropping

Monocropping is the practice of growing a single crop year after year on the same
land, in the absence rotation through other crops. Rice, maize, soybean, and wheat