Description
Green manuring is probably the only option for extending on a great scale the acreage of organic
fanning in the perennial crops of the Mediterranean basin such as olive groves. Olive growers, in
general, do not have animals so the availability of organic manures is not sufficient to maintain soil
fertility. In addition, the organic composts approved for organic farming on the market have high
prices and are sometimes speculative, in relation to their fertiliser value (Rodrigues et al., 2006). In
NE Portugal there is a long tradition in the cultivation of white lupin (Lupinus a/bus) as a means of
improving soil fertility. However, little is known about the dry matter yield and N fixation potential
of lupin in these agrosystems, and also of the transfer of fixed N to the trees. In this work the results
of dry matter yield and N recovery by lupin, vetch (Vicia villosa) and a mixture of self-reseeding
annual legumes are presented. The trial also included plots of oats (Avena saliva) and natural
vegetation.
; Ferreira, I.Q. 
