Chornyi, S. and Vilna (Poliashenko), N. 2019. Updating of "The Productivity Index of Pierce» and its application for an estimation of chernozem soils quality in the Right-bank Steppe of Ukraine. AgroChemistry and Soil Science. 88, (Sep. 2019), 31–39. DOI:https://doi.org/10.31073/acss88-04.