Application of N fertilizer significantly increased leaf area indices at 100 days (Table 1),
highlighting the usefulness of this nutrient in increasing canopy development of cassava
during early growth under Asian smallholder farming systems, as shown by Cardoso et al. (2005) under conditions of Latin America. Generally with the increased rates of N (90 and 150 Kg N), the greatest LAI was observed when the fertilizer N was applied at planting,
rather than as split applications, indicating the requirement at early stages of growth for shoot and canopy development. The exception was with 45 kg N, where LAI was greatest when applied as three split applications (S3). This could be due to the low rates used,which could be insufficient to promote optimal leaf growth. Continued application of lower rates would promote greater leaf development. The single or split application did not show significant differences in LAI between the two greater rates of N (90 and 150 kg N). Thus,smallholder farmers could derive optimal leaf growth with 90 kg N under conditions of this study in Sri Lanka as there was adequate rainfall over the season. Excess N would be
lost through leaching due to the rainfall received at the onset of the major season and thus a loss to the farmers.