3Kamau D M ,Spiertz J II,Oenema 0. Carbon and nutrientstocks of tea plantations differing in age, genotype and plantpopulation density [J] . Plant soil,2008, 307 (1 - 2): 29 -39.
4Kamau D M , Spiertz J II, Oenema 0 , eL al. Productivity andnitrogen use of tea plantations in relation to age and genotype[J] . Field Crops Research, 2008, 108 ( 1 ) : 60-70.