Phosphorus the outcome of climatic, biotic, and landscape

Phosphorus (P) is one of the most important mineral nutrients in
agricultural systems, generally the second most limiting nutrient for plant
production.
Its source is almost entirely geological, from rocks and volcanic ash, and all
life depends on its release during weathering and soil formation. During
pedogenesis, the rock-bound P pool decreases and P enters soil, plant,
microbial, and aqueous pools, where it is incorporated into organic compounds.
With the increasing population in the world and changes in diets are putting further pressure on the P
demand, as agricultural production will have to increase further to meet food
demand. For that continuous supply of agricultural inputs are essential.
Among them phosphorus containing fertilizer will create high demand. P reserves
in the world depleting in a higher rate (Cordell and White, 2011). So
the P reserves in soil should be effectively use in agriculture as a solution
for P scarcity.

 

Phosphorus in
soil exists in different forms. Simply they are plant available form or soluble
P, organic P, primary P type minerals, secondary compounds and P sorbed to
mineral surfaces(Hansen et al., 2002). The removal of P from soil occurs
mainly due to plant uptake, leaching, runoff and soil erosion (Kruse et al.,
2015). Phosphorus
in soil varies with depth and is the outcome of climatic, biotic, and landscape processes interacting over
time on parent material (Raphae et al., 2015).  Wet-zone of Sri Lanka is an economically and
environmentally important area which contribute considerably for the
agricultural productivity. Moreover, areas such as Nuwara Eliya have been
subjected for focus area for environmental concerns due to intensive vegetable
cultivation .
For the last fifty years vegetable
growers in Nuwara Eliya have been adding very much more chemical fertilizers without
considering crop requirement (Wijewardena
and Amarasiri, 1990; marikar et al., 1996).  As a result accumulates
P  in surface horizon. Nuwara
Eliya soils are highly polluted with phosphorus and would thereby pollute the
water bodies downstream. This may cause eutrophication which is
one of the most discussing problems related to environment nowadays

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Globally, existing
estimates of soil total phosphorus (P) stocks are very uncertain because they
are derived from scattered data, with large gaps over many areas of the Earth.
Here, we derive spatially clear estimates and  distribution stock of total P and available P in
vegetable grown sub catchment in Nuwara Eliya, Sri Lanka. Knowing the spatial
distribution of soil P is important because it enables
the evaluation of ecosystem and agricultural productivity, environmental quality, and the management of
biodiversity. Here we present 4 map of total
soil P stocks and available P stocks, in the 0–30 cm and 30-60 cm layer, over vegetable land use sub catchment in Nuwara Eliya. There
are concerns related to the long-term security of supply of P fertilizers and a
need to understand and monitor the P-stocks in soils