Development of Quick Test Method for Soil pH, Nitrat, Phosphorus, and Potassium Combining Chemicals and Phone Cellular Application

Conventional soil analyses are time-consuming therefore soil quick test (QT) method is needed.  This study was to assess the accuracy of the results of soil pH, nitrate, phosphorus (P), and potassium (K) analysis determined by QT method developed by Akvo and calibrated with laboratory results as references. The colorimetric-based QT method was performed on the soil sample extracted by Mehlich 1 and the color was developed by dipping strip test paper in supporting chemical solutions. A smartphone camera was used for the reading and the results were directly displayed on the smartphone screen. The calibration models for QT method were created by stepwise multiple linear regression involving the correlated soil chemical properties.  The values of calibrated QT showed significant correlations with the values from laboratory especially for soil pH, nitrate and P.  However, the results suggested that QT developed by Akvo could be used for nitrate due to having relatively high correlation with that of Laboratory. QT for soil pH, available P and exchangeable K needs some improvements due to having low correlations with those of Laboratory.