TURFGRASS INFORMATION FILE - MICHIGAN STATE UNIVERSITY,USA Comparacao de vavios indices de potassio do solo com o potassio extraido pelo azevem-perene em vasos (Comparison of several soil potassium indices with potassium uptake by perennial ryegrass in pots) da Gama, M. V. 1979. Agronomia Lusitana. 39(4): p. 305-334. click here 4572