This study was carried out to investigate the characteristics of silica extracted from rice straw obtained from rice farming region of Pekalongan. The silica was obtained using sol-gel method, which involves extraction of silica using alkalis solution and gelation of the silica using acid solution. It was found that the highest yield was obtained from the extraction using 5% KOH solution with the extraction time of 60 minutes, and gelation pH of 7.0. The SiO2 chemical composition was confirmed by EDS and FTIR and the amorphous by XRD. SEM analysis indicates the existence of various particle sizes distributed irregularly, which reflects that homogeneous sample has not been achieved in this study. Nanosilica powders with a 45,3869 nm average poresize and have specific surface (94,761 m2/g). Silica nanoparticle fertilizer applied to various plants such as peanuts, tomato and soybean. Based on the research can be seen that the plant height and number of leaves of plants with nanosilica fertilizers more show very rapid growth.