Response of banana to controlled release urea

Banana is a perennial crop that grows for 10 to 14 months for one harvest and can produce more than 150 t/ha of dry biomass and up to 60 t/ha of fruit. To support such large biomass production, banana requires high rates of fertilizer application and more than ten applications. In order to reduce the number of fertilizer applications, a field trial was conducted to study effects of controlled release urea (CRU) versus regular urea (RU) in relation to rates, timing and blends of the two on banana yield and economic returns. The trial consisted of nine N treatments including: zero N; 100% RU with six splits (one basal + five topdressings); 100% RU with two splits (one basal + one topdressing); 100% CRU with three splits (one basal + two topdressings); three reduced CRU rates (80%, 70% and 60%) applied in two splits; two combined treatments of 80% CRU+20% RU applied three times and 80% CRU+20% RU applied twice; and one combined treatment of 80% CRU+20% RU using 80% of total N rate, split twice. The fertilizer rates of 100% N treatment provided 673-178-878 kg N-P₂O₅-K₂O/ha. The CRU was a polymer coated urea (42% N) from Agrium and RU was purchased from the local market (46% N). The basal fertilizer was incorporated into soil and the topdressings were side-banded at early growth stages and broadcast at later stages.

Results showed that the two 100% CRU treatments produced the highest banana yield with 33 t fruit/ha with two splits and 34 t/ha with three splits. These yields were 2.2 t/ha (7%) and 3.0 t/ha (10%) higher than the 100% RU treatment. All the other treatments, whether they were the reduced CRU rates or the blends of CRU+RU with the full rate N, produced significantly lower fruit yield. The higher yields of the two 100% CRU treatments were attributed to the enhanced banana fingers/bunch (7 to 8%) and the increased single finger weight (1 to 3.9g) as compared to the 100% RU treatment. Nitrogen recovery by banana in the 100% CRU treatment was 8% higher than in the 100% RU treatment. The two 100% CRU treatments also produced the highest income (US$1,140 and US$1,590).

The results suggest that use of CRU instead of urea is feasible and profitable for banana. It not only significantly reduced N application from 6 to 2 or 3 times, but also increased yield and farmers’ income.