Comparative Assessment of Inorganic and Water Hyacinth Integrated Compost-Based Top-Dressing on Growth and Yield Parameters in Turmeric (Curcuma longa L.)

Turmeric (Curcuma longa L.) is a nutrient valuing crop which responds effectively and positively to fertilizer application. However, the application of chemical fertilizer continuously can affect negatively on soil health and environment. The integrated use of inorganic and organic fertilizer appears to be a good alternative approach as organic sources help to maintain soil health. Compost produced using water hyacinth (WH) (Eichhornia crassipes) has been effective in substituting inorganic fertilizers. The objective of this study was to investigate the replacement of some inorganic fertilizers in top dressing by WH compost while increasing yield in turmeric cultivation. The control experiment was 100% inorganic fertilizer (T1), according to the Department of Export Agriculture recommendation, while other treatments were 25% inorganic fertilizer + 20 Mt ha^-1 compost (T2), 50% inorganic fertilizer + 20 Mt ha^-1 compost (T3), and 75% inorganic fertilizer + 20 Mt ha^-1 compost (T4). The experiment was conducted in an RCBD design with three replicates with 12 plants in each replicate. Plant height, number of leaves, number of tillers, leaf blade length, leaf width, leaf petiole length, number of mother rhizomes, number of primary fingers, number of secondary fingers, fresh yield per plant, and canopy biomass were measured as parameters. The results indicated that all parameters were significantly affected by the treatments (p<0.05). The significantly highest fresh yield per plant (680.32 g) associated with moderate to strong correlations in most of the parameters in T3, suggested that 50% recommended dose of inorganic fertilizer combined with 20 Mt ha^-1 compost is the best option for integrated fertilizer application. T4 (75% inorganic fertilizer + 20 Mt ha^-1 compost) recorded the significantly highest vegetative growth with no significant correlations of the parameters with the yield. These results suggest that T3 (50% inorganic fertilizer + 20 Mt ha^-1 compost) is the most effective combination of inorganic and compost fertilizer as the top dressing among the tested combinations for maximum turmeric growth and yield.