Mine Closure - Mining and the Environment: From Ore to Metal - page 816

Soil Amendments and Fertilization

Soil characteristics can be improved by a variety of practices, including:
●

Addition of lime to raise pH and to improve texture of clayey soils;

●

Addition of gypsum or sulphur to lower pH;

●

Addition of organic matter such as manure, sewage sludge, compost or green manure
to improve the texture and moisture retention properties;

●

Fertilization, involving the addition of nutrients and elements essential for the growth
of most plants.

Simple agronomic tests are used to assess the need for soil amendments. Many handbooks
are available that provide detailed instructions for assessing soil amendment require-
ments and for their practical application. See for example, Minerals Council of Australia
(1998). In agricultural and production forestry situations, repeated harvesting will pro-
gressively remove nutrients and deplete some elements, requiring repeated fertilizing.
In natural vegetation communities, however, the nutrients are recycled through natural
processes as vegetation dies, decomposes and is incorporated in the soil for subsequent
uptake.

Simple agronomic tests are
used to assess the need for soil
amendments.

Mulching

Mulching is another practice that can be highly benei cial to the rehabilitation process.
Land clearing usually produces plenty of organic matter and, even if the timber is har-
vested, the branches and leaves can be shredded, chipped or trittered to form a useful
mulch which, when spread over the ground surface, has the following benei ts:
●

Absorption of raindrop impact, a major initiator of soil erosion;

●

Shading and cooling of soil layer;

●

Assistance in retaining soil moisture;

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As it decomposes, release of nutrients, and

●

Providing food and shelter for a range of organisms; once the appropriate invertebrates
colonize the area, additional organic matter will be incorporated in the topsoil.

It should be recognized, however, that nutrients, particularly nitrogen, are consumed by
the mulch as it decomposes. It may therefore be important to add sufi cient fertilizer that
nutrients are not depleted to levels that would limit the growth of vegetation.

Nutrients, particularly nitrogen,
are consumed by the mulch as it
decomposes.

Establishment of Vegetation

Cover crops are commonly planted to provide groundcover, pending the establishment of
the vegetation required for the intended land use(s). The purposes are (Hypers et al . 1987):
●

To protect the soil against the
full force of the rainfall, and the
retention of the soil.

To protect the soil against the full force of the rainfall, and the retention of the soil
(short-term erosion control);

●

To protect the soil against strong heat so that the humus is broken down less quickly;

●

To eliminate weeds by water and light dei ciency;

●

To increase the humus level and structure of the soil, by working in the crop and litter,
and

●

To increase soil fertility.