Many researches related to P­₂O₅ measurement using Vis-NIR spectroscopy have been performed in laboratory. There are not so many researches to perform on-the-go measurement of P­₂O_5. One of the researches which performed using on-the-go measurement of P­₂O₅ was carried out by Mouazen et al (2007). The objectives of this paper are to measure the soil P₂O₅ with on-the-go Real Time Soil Sensor (RTSS) and to create the soil P₂O₅ maps for site specific management purposes.

The RTSS was attached to a tractor by three point links. It’s travelled over the fields. The RTSS equipment captures several kinds of data simultaneously, such as the soil reflectance in the Vis-NIR range which was collected in the range between 350-1700nm wavelength, soil color images using a CCD camera, dGPS for position information data collection, etc.

The experiment was conducted on a-4ha commercial farm in Memuro, Hokkaido, Japan. For analysis purposes, 72 soil samples were collected to calculate standard curves. The Vis-NIR spectra data were recorded at the same position as where the soil sample was collected. The multivariate linear regression technique partial least squares (PLS) with the full cross validation was employed for analysis followed by the use of the multiple coefficient of determination (R2) and the root mean square error (RMSE) for evaluation. The soil P₂O₅ Maps were created using Inverse Distance Weighted (IDW), Arc GIS 9, USA.