9Regmi AP, Ladha JK, Pasuquin E, et al. The role of potassium in sustaining yields in a long-term rice-wheat experiment in the Indo-Gangetic Plains of Nepal [ J ]. Biology and Fertility of Soils ,2002,36:240 - 247.
10Cassman KG, Kerbu TA, Roberts BA, et al. Differential response to two cotton cultivars to fertilizer and soil potassium [ J ]. Agronomy Journal, 1989,81 : 870 - 876.
