Yield, irrigation production efficiency and economic returns of broccoli under variable drip irrigation and lateral spacing.

Field studies were carried out for 2 years (2001 – 2003) on clay loam soil to determine the effect of variable irrigation (50, 100, 150 and 200% of pan evaporation replenishment) and lateral spacing (0.5 and 1.0m) on yield, irrigation production efficiency and economic return of broccoli (Brassica oleracea). The irrigation was applied when sum of daily pan evaporation (5 years) from United States Weather Bureau (USWB) Class A open pan reached approximately up to 16.3mm after accounting for rainfall. The crop was irrigated by drip irrigation system. Irrigation at 150% of pan evaporation replenishment and 0.5m lateral spacing resulted in higher marketable yield of primary and secondary flowers. A further increase in irrigation amount resulted from 200% pan evaporation replenishment reduced marketable flower yield significantly. The higher irrigation production efficiency was recorded at 50% of pan evaporation replenishment and 0.5m lateral spacing and it decreased significantly with an increase in irrigation amount and lateral spacing Irrigation at 150% of pan evaporation replenishment resulted in a higher net return and benefit-cost ratio. The lateral spacing of 1.0m gave higher net return and benefit-cost ratio as compared to lateral spacing of 0.5m. The seasonal water applied and marketable flower yield, gross return, net return and benefit-cost ratio exhibited quadratic relationship which can be used for optimising economic return of broccoli under variable irrigation and lateral spacing. The results revealed that drip irrigation system is profitable for broccoli production inspite of high initial investment.Journal of Science and Technology (Ghana) Vol. 27 (2) 2007: pp. 109-11