AVAILABLE PHOSPHORUS “P” DETERMINATION
APPARATUS USED: Electronic weighing scale, 50ml beaker, glass stirring rod, filter paper, funnel, volumetric flask, spectrophotometer
REAGENTS USED: Phosphorus extraction solution “NH4F solution”, ammonium molybdate, diluted stained chloride, distilled water.
PROCEDURES:
2g of soil sample each from both areas was weighed into separate rinsed labeled 50ml beakers (indicating either upland or lowland).
10ml of phosphorus extraction solution was added to the sample and stirred with a rinsed glass stirring rod.
A filter paper was placed in a funnel held by a clamp and a labeled beaker indicating the area of sampling was placed beneath the funnel to collect the filtrate. The suspension was stirred and poured into the filter paper to separate the filtrate from the residue.
2ml of the filtrate was fetched from the beaker using a pipette into a rinsed volumetric flask.
2ml of ammonium molybdate was also added and distilled water was added to the solution until it reached a calibration of 48ml.
1ml of stannous chloride was added to the solution which changed to sky blue in colour; lowland was darker.
1ml of distilled water was added to calibrate to solution to 50ml.
A cubate was rinsed and filled with the solution.
The cubate was Inserted into a cubate hanger and placed into the spectrophotometer at initial wavelength of 660m for readings.
The readings are as follows;
Absorbance for upland (dry land) = 0.559
Absorbance for lowland (wet land) = 0.445
CALCULATIONS:
Available phosphorus =
Where 1st dilution factor () = = 5
And 2nd dilution factor () = = 25
Upland (dry land):
Available phosphorus “P” = =
“P” = 1.3763
“P” = 1.38mgKg-1
Lowland (wet land):
Available phosphorus “P” = =
“P” = 1.0965
“P” = 1.10mgKg-1
CONCLUSION
The soil of the lowland is less concentrated in phosphorus compared to the upland soil i.e. the upland soil have more ability to fix more phosphorus than the lowland. Therefore through fertilizer application more phosphorus P is fixed in the lowland soil.
