Effetti della concimazione azotata su frumento duro in un tipico ambiente mediterraneo

After a brief description of the pedo-climatic environment of Sardinia the results of the experiments carried out by the Istituto di Agronomia ge· nerale e Coltivazioni erbacee dell'Università di Sassari and of the Centro Regionale Agrario Sperimentale di Cagliari on the usage of nitrogen fertilization on durum wheat are presented. Some aspects are examined related to the quantities of nitrogen used at the time of supply, various types of fertilizers in relation to seasonal course, the nature of the soil, the preceding cultures and the different cultivars. The effectiveness of the fertilization is closely related to the water reserve, particularly during the biological phases following heading. The production increases, obtained by supplying nitrogen at the moment of sowing or in winter time, are a consequence due mainly to the increased number of ears per surface unit. Positive effects on the productivity of the ear and on the weight of the kernel are observed with a late supply of nitrogen, provided, naturally, that there is in the soil enough water supply. In conditions where there is absence of water even not very high quantities of nitrogen cause a decrease of the yield, consequent to a reduction of the kernel weight. Besides the productive aspects, the effects of the nitrogen are also examined on the qualitative features of the seed, in particular on the yellow berry and on the proteic content.