A digital NPK data recording system based on photocell was developed to record and transmit the results of NPK to controller of smart variable rate liquid fertilizer applicator. For the measurement of NPK in the soil of oil palm plantation, itsmeasurement procedure was modified with consideration of Environmental Sciences light factor to improve the accuracy.Digital NPK data recording system offers remote monitoring approach for recording NPK results from existing DSTK without altering its original circuit or program algorithm. The optimum Environmental Sciences light conditions (18-21 W/m2) were determined for accurate measurement of NPK using DSTK. For oil palm plantations, a new NPK measurement method was defined to enhance the accuracy of digital NPK data recording system.In oil pam plantations this system can play a role as a component of Precision Agriculture (PA) to measure NPK quickly at inexpensive rates relieving the farmersfrom high cost and longer time. With new data recording capability and modified NPK measurement method, this system can be linked and used with the smart variable rate liquid fertilizer applicator at improved accuracy.