Page 23 - Soil Degradation, Conservation and Remediation

8 1 Soil Resources and Soil Degradation

Table 1.1 Land quality classes and their properties
Land quality Properties
Class
I Class I land is the prime land. The soils are highly productive with few limita-
tions. Moisture and temperature conditions are ideal for annual crops. Soil
management consists largely of sensible conservation practices to minimize
erosion, appropriate fertilization, and use of best available plant materials.
Risk for sustainable grain crop production is generally <20 %
II and III The soils are good and have few problems for sustainable production. Care must
be taken to reduce degradation, particularly for Class II soils. The lower
resilience characteristics of Class II soils make them more risky, particularly
for low-input grain crop production. However, their productivity is generally
very high, and consequently, response to management is high. Conservation
tillage is essential, buffer strips are generally required, and fertilizer use must
be carefully managed. Due to the relatively good terrain conditions, the land is
suitable for national parks and biodiversity zones. Risk for sustainable grain
crop production is generally 20–40 %, but risks can be reduced with good
conservation practices
IV, V, VI If there is a choice, these soils must not be used for grain crop production,
particularly soils belonging to Class IV. All three classes require important
inputs of conservation management. In fact, no grain crop production must be
contemplated in the absence of a good conservation plan. Lack of plant
nutrients is a major constraint, and so a good fertilizer use plan must be
adopted. Soil degradation must be continuously monitored. Productivity is not
high, and so low-input farmers must receive considerable support to manage
these soils or be discouraged from using them. Land can be set aside for
national parks or as biodiversity zones. In the semiarid areas, they can be
managed for range. Risk for sustainable grain crop production is 40–60 %
VII These soils may only be used for grain crop production if there is a real pressure
on land. They are definitely not suitable for low-input grain crop production;

their low resilience makes them easily prone to degradation. They should be
retained under natural forests or range, and some localized areas can be used
for recreational purposes. As in Class V and VI, biodiversity management is
crucial in these areas. Risk for sustainable grain crop production is 60–80 %
VIII, IX These are soils belonging to very fragile ecosystems or are very uneconomical to
use for grain crop production. They should be retained under their natural
state. Some areas may be used for recreational purposes but under very
controlled conditions. In Class IX, which is largely confined to the boreal area,

timber harvesting must be done very carefully with considerable attention to
ecosystem damage. Class VIII is mainly the deserts. Risk for sustainable grain
crop production is >80 %
Adapted from Eswaran et al. ( 1999 )

The properties of the different land quality classes are shown in Table 1.1 .

1.4.4.2 Assumptions

The classification was intended to be universal and several assumptions were made: (1)

It focuses on the inherent ability of soil to produce grain crops in a sustainable manner.
Fragile ecosystems, such as wetlands, the cold tundra zone, and deserts are excluded