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Hosphorus Status Of Three Wetland Types
[A CASE STUDY OF AKWA IBOM STATE, SOUTH EASTERN NIGERIA]
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Phosphorus is one of major essential nutrient elements required by
plants. It is the second most deficient plant nutrient element as more
than ninety percent (90%) of the world soil require moderate to high
phosphorus levels for optimum crop growth and development (Rashid,
1994). Phosphorus plays a vital role in energy transformation and
photosynthesis. The quality of fruits, forages, vegetables and grain
crops as well as disease resistance of crops are enhanced under adequate
phosphorus availability (Sanyal and De Datta, 1991).
The major
sources of phosphorus in the soil are the parent materials, inorganic
fertilizers, plant and animal residues (Agbede, 2009). The availability
of phosphorus to plants in soils is usually linked to the relative
abundance of various forms of phosphorus, such as total phosphorus,
organic phosphorus, inorganic phosphorus and available phosphorus.
Widespread
deficiencies of phosphorus have been reported (Nnoke, 1980; Dyboh,
1999) as a major constraint to crop production in Southeastern Nigeria
due to over cultivation, low total P and insufficient replenishment of
lost P from soils. A major loss leading to phosphorus deficiency in
these soils was attributed to phosphorus fixation by sesquioxides.
According to Osodeke and Kamalu (1992), Ibia and Udo (1993), Sharawat,
Abekoe, and Diatta (2001), Osodeke (2000), Abekoe and Sharawat (2001),
(2003) and Osodeke and Ubah, (2005), highly weathered soils of the humid
tropics rich in 1:1 clay minerals (kaolinitic clays) and high contents
of sesquioxides are not only low in phosphorus but the applied soluble
phosphorus is converted into forms not readily available to crops and as
such limit crop production and productivity. This immobilization often
described as fixation, precipitation, sorption or adsorption depends on
the amount of phosphorus added, the nature of the fixation product and
on the soil physical and chemical properties (Osodeke, 2000).
There
is inadequate information on the phosphorus status of wetland soils in
Akwa Ibom State. Therefore, the study seeks to investigate the
phosphorus status of three wetland types in Akwa Ibom State.
The following were the specific objectives:
To determine some physical and chemical properties of three wetland types.
To assess the levels of total, organic, inorganic and available phosphorus in three wetland types.
To determine the phosphorus fixing capacity of three wetland types.
To assess the relationship between physical and chemical characteristics and phosphorus forms in the soil
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