Widowati, L. R., and . Sukristyonubowo. “Dynamics of PH, Ferrum and Mangan, and Phosphorus on Newly Opened Paddy Soil Having High Soil Organic Matter on Rice Growth”. JOURNAL OF TROPICAL SOILS, vol. 17, no. 1, May 2019, pp. 1-8, doi:10.5400/jts.2012.v17i1.1-8.