The phosphorus cycle describes the movement of phosphorus through lithosphere, hydrosphere, and biosphere. Phosphorus is essential for life and is found in DNA, bones, teeth, and used in matches. In the phosphorus cycle, weathering releases phosphorus from rocks into soil. Microbes convert phosphorus in soil into soluble inorganic forms that can be absorbed by plants. Plants and animals absorb phosphorus, which returns to the environment through decomposition. The cycle continuously moves phosphorus from the lithosphere into the biosphere and back again.

1. Phosphorus Cycle

2. Definition and significance
 Phosphorus cycle is defined as the exchange or the movement of phosphorus with
the lithosphere, hydrosphere, ecosphere. In this cycle the atmosphere is not a part
of this cycle.
 It is a most important element in our life cycle like it is present in our DNA, amino
acids, phospholipids in the cell membranes, it is also present in our bones and
teeth’s, we also use it in the match box, important nutrient for plants etc. and lots
of examples are there.
 The transfer of energy among the living system depends upon the phosphates by
the ATP, ADP and AMP.

3. Different steps of Phosphorous cycle
 The major source of phosphorus in soil is the Phosphorus Rocks, by the microbial
activities it is converted into the soluble and inorganic form mainly as H3PO4
 The soil contains the organic phosphates in a very large quantities, but it cannot be
used by the plant directly as it solely depends upon the availability of soluble
phosphate ion which is mainly H3PO4
 So from the P- containing organic compounds are converted into inorganic for P-
containing compounds by the microbial activity this process is called as the
mineralization.
 The availability of soluble phosphate ions also depends upon the pH of the soil at
lower pH Ca(H2PO4)2 exits which has higher solubility but at higher pH the
solubility decreases due to the presence of Ca3(PO4)2 which has the lowest
solubility .

4. Different steps of Phosphorous cycle
 Weathering Since the main source of phosphorus is found in rocks, the first step of the
phosphorus cycle involves the extraction of phosphorus from the rocks by weathering.
Weather events, such as rain and other sources of erosion, result in phosphorus being
washed into the soil.
 Absorption by Plants and Animals once in the soil in the form of soluble ions which is
formed by microbial activity and the process, we know is mineralization, plants, fungi,
and microorganisms can absorb phosphorus and grow. In addition, phosphorus can
also be washed into the local water systems. Plants can also directly absorb phosphorus
from the water and grow. In addition to plants, animals also obtain phosphorus from
drinking water and eating plants.
 Return to the Environment via Decomposition When plants and animals die,
decomposition results in the return of phosphorus back to the environment via the
water or soil. Plants and animals in these environments can then use this phosphorus,
and step 2 of the cycle is repeated.

5. Source- Environment-research.ox.uk

6. SOURCE- ENVIRONMENTAL CHEMISTRY A.K DE