Sampaio, E. V. de S. B. and Salcedo, I. H. (1991) “Nutrient cycling in sugarcane. V. Potassium balance during four cropping periods”, Pesquisa Agropecuaria Brasileira, 26(9), pp. 1323–1335. doi: 10.1590/S1678-3921.pab1991.v26.3472.