Purpose: Environmental-friendly organic fertilizers reduce the adverse impacts of chemical fertilizers. This study was conducted to formulate organic liquid fertilizers using selected plant materials i.e., Tithonia diversifolia, Mikania scandens, Chromolaena odorata and Gliricidia sepium with selected organic wastes to compare the efficacies of foliar and soil-applications over the growth of leafy vegetables; Basella alba and Centella asiatica.Research Method: Selected plant materials were allowed to decompose for two months and thereafter fish waste was hydrolyzed separately with fruit wastes of Carica papaya, Ananas comosus and (1:1 w/w) mixture of both were mixed and nutrients analyzed. Fertilizers were foliar and soil-applied separately on C. asiatica and B. alba in RCBD in pot trials.Findings: Fertilizer formulated with decomposed plants + fish waste hydrolyzed with C. papaya significantly recorded the highest N (0.57%), P (0.06%) and highest growth of C. asiatica and B. alba over both soil and foliar applications followed by the fertilizer formulated with decomposed plants + fish waste hydrolyzed with C. papaya + A. comosus. Foliar-application of B. alba significantly showed the highest growth than the soil-application [shoot height (36.6±3.4 cm vs 30.0±1.5 cm), number of leaves per plant (21.7±1.4 vs 17.5±0.8) and plant fresh-weight (61.5±1.8 vs 55.6±0.9 g)] whereas, C. asiatica indicated no significant difference considering both fertilizer application methods. Research limitation:Pot experiments were carried out to provide uniform soil conditions for the experiment which was the main limitation compared to field trials. Originality/value:The formulated novel fertilizers could be utilized effectively in organic farming for safe and healthy leafy vegetables which reduce the adverse impacts of chemical fertilizers.

Tithonia diversifolia, Sphagneticola trilobata, Mikania scandens, Lantana camara, Chromolaena odorata, Panicum maximum and Mimosa pigra are common weeds in Sri Lanka. This study was aimed to assess the nutrient release potential and the weight loss dynamics during leaching of the above weeds to utilize them as organic liquid fertilizers. Thirty samples from each species of oven-dried leaves (5 g) were placed separately in 1 L of distilled water. Three samples of each species were randomly collected at 1, 3, 5, 7, 14, 28, 42, 56, 70 and 84 days and the massloss, electrical conductivity (EC), pH and nutrient contents of the leachates were determined. Four fertilizers (FP1; the selected weeds Tithonia diversifolia + Mikania scandens + Chromolaena odorata (W), FP2; (W) + topsoil, FP3; (W) + topsoil + coconut husk ash and FP4; (W) + topsoil + coconut husk ash + fish waste) were formulated and based on the nutrient contents the highest nutrient containing FP3 and FP4 were applied on Basella alba. Mass-loss was higher (p<0.05) for Mikania scandens (97%) followed by Tithonia diversifolia (95.8%) and the lowest for Panicum maximum (63.7%). EC and pH of leachates were increased over the time indicating the highest in Mikania scandens (2139±4.7 µS cm -1 ) and Lantana camara (7.86±0.06) respectively, and the lowest in Panicum maximum (877±7.6 µS cm -1 , 7.40±0.02). Nutrient contents of the leachates of Tithonia diversifolia, Mikania scandens and Chromolaena odorata were higher than those of Panicum maximum. FP4 revealed the highest nutrients and growth performances of shoot height (25.0±0.9 cm), number of leaves (12.0±0.6), leaf area (70.7±1.6 cm 2 ), plant fresh weight (56.1±1.2 g) of Basella alba. The results are suggestive of the potential of utilizing Tithonia diversifolia, Mikania scandens and Chromolaena odorata for the formulation of organic fertilizers which would in turn be a low-cost strategy for effective control of these weeds.