Characteristically, tropical soils have been known to be fragile due to the very high extreme weather conditions it faces. Such extremes include rainfall, sunshine and other weather conditions. This situation has led to high rate of leaching, acidity, erosion and most importantly nutrient depletion.
These have made our soils to
become vulnerable and so delicate (poor) that if we do not improve its
fertility status, it cannot continue to support food and fibre production for
our increasing population.
Therefore, soil is an important natural nutrient medium that supports crop growth and development and good root development to enable the plant complete its crop cycle.
It provides also a habitat for soil organisms important in agriculture
especially those associated in carbon, nitrogen and phosphorus cycling and
oxidation/reduction processes in soil. Hence the fertility status of the
tropical soil is essential to enhancing good crop quality and production.
By
the end of this article, you will be able to discuss the tropical soils and
explain tropical soil fertility.
Definition of Soil Fertility
A
fertile soil may be defined as that which has the power to supply the right amount
of nutrients to the plants and in the right proportion. The fertility of an
agricultural soil can also be defined simply as ‘its capacity to produce the
crops desired’, emphasizing the idea that soil fertility ‘is an outcome of the
effects of many kinds of living organisms, and chemical and physical processes
acting on the inert parent materials from which soil is made’.
Soil fertility is the level or status of a given soil with respect to its ability to supply the needed nutrients for plant growth.
In effect, it is the nutrient supplying power of the soil. It is also defined as the quality of nutrients which enables or helps a given soil to make provision of the right nutrients in the right quantity and in the right proportion for growth of a specific plant or crop when all necessary environmental factors such as temperature, water, pH, light are adequate / favorable.
Soil fertility is the result of the
interactions between the biological, chemical and physical properties of soil
due to soil type and land use, and the effects of climate.
It is related to the potential for the sustainable production of crops and animals and can be assessed and/or described in various ways.
Soil fertility can be
viewed as an ecosystem concept integrating the diverse soil functions,
including nutrient supply, which promote plant production.
Many
soil properties interact to impact on crop growth, with both trade-offs and
compensating effects.
Importantly, economics plays a critical role as farmers will only strive to maintain soil fertility through appropriate practices if it pays the farmer, preferably in the short term.
Concerns about soil degradation have highlighted the need to
include a much wider range of potential functions of soil alongside plant production
within any definition of soil quality and soil fertility is now considered as
one aspect of the broader concept of soil quality.
Factors Affecting Tropical Soil Fertility
It
is important to know and fully understand the chemical, biological and physical
properties of a soil as well as their relationship in the soil – plant –
atmosphere continuum that control nutrient availability.
One
of the biggest constraints in soil fertility is to develop and implement soil,
crop and nutrient management approaches that improve the quality of the soil,
water and air.
Therefore, the factors that influence tropical soil fertility include those that affect plant growth and development.
Such factors include:
· ph
of soil (soil reaction)
·
Climate factor especially temperature and precipitation (moisture)
·
Activities of soil micro organisms
·
Soil organic matter content
·
Nutrient imbalance
·
Light energy (Radiant energy)
·
Soil type and Soil Structures.
Key Limitations of Tropical Soils
With
increasing knowledge about the extent and distribution of soils in tropical
regions, limitations for agricultural production and other purposes could be
quantified.
It
was found that tropical soils are as diverse and varied as those of temperate regions
this makes it difficult to generalize about their distribution and limitations
for agriculture and other uses.
Some
workers have made estimates based on the Fertility Capability Soil
Classification System about tropical soils limitations.
Tropical Soil Limitations
i.
Mineral stress, defined as nutritional deficiencies or toxicities related to
chemical composition or mode of origin, affects about one-fifth of the soils in
Africa
ii.
That two-thirds of the soils of the humid tropics have low nutrient reserves.
iii.
Nearly 60% suffer from Al toxicity.
iv.
38% of the land has soils with high P fixation.
v.
based on the FAO–UNESCO maps, that one-quarter of the soils in Africa have
medium to low potential
vi.
And that more than 50% of the land is fragile and not productive.
Conclusion on Soil Fertility in the Tropics: Definition, Factors & Key Limitations
Tropical
soils are highly diverse, with some soils having a high production potential.
However, there are many areas where the soil resources suffer from serious
limitations hindering agricultural production and development.
Some
soils have a very low chemical fertility, are extremely acid or contain toxic
substances, but the exact extent of low-fertility soils and the extent of spare
land is, despite advanced mapping techniques, still open for debate.
From
this article, you have learnt about the fertility of tropical soils.
Some of the key things leant include the following;
- The definitions of soil
fertility
-
Some factors affecting fertility of tropical soils
-
Key limitations of tropical soils.
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