Page 21 - Soil Degradation, Conservation and Remediation

6 1 Soil Resources and Soil Degradation

grow satisfactorily or not, depending on the provision of other requirements from the
soil, including air, water, and temperature. If the soil is fertile but the soil is not
appropriately managed, production of crops may be low. So, fertile soils may or may
not be productive depending on other properties and soil management. By manage-
ment infertile soils may be made fertile and productive.

1.4.2 Soil Productivity

Soil productivity is the ability of soil to give optimum yields under standard set of
management practices. Yield is the amount of production of biomass. Yield may be

biological (total biomass) or economic (grains, vegetables, wood, fiber, or other
products such as resins, sugars, and oils). A poorly fertile soil may be made produc-
tive by fertilizer addition, and a dry soil may be made productive by irrigation. A
waterlogged soil may be naturally productive for rice, but not for potato. Draining
the soil may make it productive for potato, too.

1.4.3 Soil Health

Soil health is defined as the continued capacity of soil to function as a vital living
system, by recognizing that it contains biological elements that are key to ecosys-
tem function within land-use boundaries (Doran and Zeiss 2000 ; Karlen et al. 2001 ).
These functions are able to sustain biological productivity of soil, maintain the qual-
ity of surrounding air and water environments, as well as promote plant, animal, and
human health (Doran et al. 1996 ). Soil health is the expression of ability of a soil to
meet its range of ecosystem functions as appropriate to its environment. This term
is used to assess the ability of a soil to sustain plant and animal productivity and
diversity, maintain or enhance water and air quality, and support human health and
habitation. It underlies that soil is not just a growing medium; rather it is a living,
dynamic, and ever-so-subtly changing environment.

1.4.4 Soil Quality

The soil quality concept evolved in the early 1990s (Doran and Safl ey 1997 ;

Wienhold et al. 2004 ), and the fi rst official application of the term was approved by
the Soil Science Society of America Ad Hoc Committee on Soil Quality. It was

discussed elaborately by Karlen et al. ( 1997 ). Soil quality has been defined as “the
capacity of a reference soil to function, within natural or managed ecosystem
boundaries, to sustain plant and animal productivity, maintain or enhance water and