As mentioned in the earlier report, we conducted an experiment to determine the effect of various factors on the ground penetrating radar (GPR) depth measurement. In the sixth quarter of this project, we analyzed the data of this experiment and produced the results for the comparison of the new calibration system with the previously available calibration methods. After the analysis, we found that: (a) the GPR measured root depth becomes smaller as the dielectric constant increases, (b) the error of GPR measured root depth becomes bigger with the increase of depth, and (c) the GPR frequency and root diameter seems to have little to no effect on the GPR measured depth. Due to the COVID-19 pandemic, the SWFREC has been closed since March 24th which has disabled us from working on the physical development of the automated GPR system. As of this time, we remain closed. Currently, we are all working from home and we have used this time to prepare a draft of a paper titled: A multi-point layered calibration method for citrus root depth measurement using Ground Penetrating Radar. We are currently going through the process of revision and editing of this draft; we will submit this paper to a scientific journal soon.We expect to return to work in the coming weeks, and we will be resuming work on the physical development and testing of the automated GPR system.The abstract of the paper (draft) can be found below:Abstract: This paper proposes and evaluates a new multi-layered point calibration method for citrus root depth measurement using ground penetrating radar (GPR). The effects of several factors such as (i) roots diameter, (ii) dielectric constant, and (iii) root depth on the GPR depth measurement have been investigated. Several multi-factor experiments were conducted using two different GPR antennas (900 MHz and 1600 MHz), different dielectric constants (2.5, 3.5, 5, 9 and 13) and at different depths (10, 20, 30, 40, 50 and 60 cm) to evaluate the influence of above-mentioned factors using five citrus branches and a stainless-steel bar in a citrus grove located at SWFREC. It has been found that the GPR measured root depth becomes smaller as the dielectric constant increases, the error of GPR measured root depth becomes bigger with the increase of depth and GPR frequency and root diameter seems to have little to no effect on the GPR measured depth.