Sondari, Nunung, and Ervina Siti Nurkhalidah. 2012. “Application of Bokashi Botom Ash for Increasing Upland Rice Yield and Decreasing Grain Pb Content in Vitric Hapludans”. JOURNAL OF TROPICAL SOILS 17 (2):157-63. https://doi.org/10.5400/jts.2012.v17i2.157-163.