Response of banana to controlled release urea

This is a continuation of a field experiment initiated in 2013 to examine the effects of consecutive application of controlled-release urea (CRU) versus regular urea (RU) in relation to rates, timing, and combinations of the two N sources. The treatments remained unchanged and included: zero N, 100% regular urea (RU) with six splits (one basal + five top dressings), 100% RU with two splits (one basal + one top dressing), 100% CRU with three splits (one basal + two top dressings), three reduced CRU rates at 80%, 70%, and 60% with two splits, two combined treatments with 80% CRU+20% RU applied in three times, and 80% CRU+20% RU applied twice, and lastly one combined 80% CRU+20% RU with 80% of total N applied twice. The fertilizer rates of 100% N treatment were 673-178-878 kg N-P₂O₅-K₂O/ha. The CRU was a polymer-coated urea (42% N) and the RU (46% N) was purchased from the local market. Basal fertilizer was incorporated into soil and the top dressings were side-banded at early growth stages and broadcast at later stages. The first-season banana seedlings were transplanted in March, 2013 and the ratoon plants were used in 2014 and 2015.

Consistent yield responses of banana to different fertilizer treatments were observed from 2013 to 2015. Yields kept increasing over time in all treatments, but decreased in the N omission treatment. The two 100% CRU treatments always produced the highest yields of 33 to 50 t/ha with two splits and from 34 to 52 t/ha with three splits. These yields were up to 2.4 t/ha (5 to 7%) and up to 3.0 t/ha (7 to 10%) higher than the 100% RU treatment. Application of 80% CRU produced slightly higher yields than 100% RU in 2013-2014, but yields started to decline in 2015. Conversely, 80% CRU+20% RU reduced yield in 2013, but increased in 2014-2015. The higher yields of the two 100% CRU treatments were attributed to enhanced banana fingers per bunch and increased single finger weight compared to the 100% RU treatment. The two treatments also produced the highest income, 1,010 to US$1,140 and 1,590 to US$1,660 higher than the 100% RU treatment.

The results suggest that use of CRU instead of urea is beneficial to banana. CRU can significantly reduce N applications from a total of six to only two or three, while also increasing banana yield and farmers’ income.