CAPACIDADE DE SUPRIMENTO DE POTÁSSIO EM DOZE CLASSES DE SOLOS EM FUNÇÃO DE CULTIVOS SUCESSIVOS DE MILHO

The forms and content of K in soil vary according to soil classes and, consequently with its degree of development, which influence the availability o K to plants. The objective of this study was to evaluate the capacity of K supply in 12 soils through four successive crops of maize. The randomized block experimental design was used, with three replications and twenty-four treatments that consisted in a combination of two doses of K (0 and 100 mg dm-3) and 12 soils. After and before the maize crops, sub-samples sized 0.2 dm3 were taken from each pot in order to determine the content of non-exchangeable K (Knt), exchangeable K (Kt) and soluble K (Ks).The less developed, in which were observed a large presence of secondary 2:1 minerals in clay fraction, showed greater ability to supply K to maize plants over the four successive crops; while the more developed where there is a predominance of kaolinite and goethite in clay fraction showed less ability to supply K, especially the sandy ones.