The Determination of Available Phosphorus in Soil: A Quick and Simple Method

The study attempts to develop a quick and a simple phosphorus (P) testing method to get the idea about the P level in the soil for farmers so that they may be able to decide the amount of phosphorus fertilizer for their cultivation. Four new phosphorus extraction methods were used which are Mogen’s method, distilled water method, basify distilled water method and acetic acid method. Extracted phosphorus was measured by Murphy and Riley colorimetric method and correlated each method with the Olsen method because Olsen method has grown in stature and reputation over the years as the best and cheapest method suitable for mild acidic to base soils. The significant correlations (r 2 ) of Mogen method, distilled water extraction method, basify distilled water extraction method and acetic acid extraction methods with Olsen method were 0.734, 0.585, 0.654, and 0.854 respectively. The acetic acid phosphorus extraction method which has the best correlation with the Olsen method was further simplified and its significant correlation with the Olsen method was 0.855. Simplified acetic acid method was the best simple P extraction method in the field level test and the extracted P can be measured using the newly introduced color chart in this study. Subsequently a field soil testing kit was developed based on the results for the farmers to test the soil phosphorus content by themselves before the cultivation and decide on phosphorus fertilizer application.