Development of Plant-Based Foliar Fertilizers from Tithonia diversifolia and Eichhornia crassipes to Enhance Growth of Irish Potato (Solanum tuberosum L.)

The aim of this study was to develop plant-based foliar fertilizers from Tithonia diversifolia and Eichhornia crassipes ashes and evaluate their effects on Irish potato ( Solanum tuberosum L.) growth under Kenyan field conditions. Potato production is constrained by declining soil fertility, rising fertilizer costs, and impacts associated with synthetic inputs. Soil samples collected from Limuru Sub-County, Kiambu County, were analyzed for physicochemical properties, while plant ashes were characterized for potassium and phosphorus. Foliar fertilizer extracts were prepared from individual ashes and a 1:1 (w/w) mixture. A field experiment was conducted using a randomized complete block design comprising four treatments: untreated control, T. diversifolia fertilizer, E. crassipes fertilizer, and the combined formulation, each replicated three times. Plant height, leaf area, fresh weight, and dry biomass were measured 60 days after planting. The soil was slightly acidic and suitable for potato production, but exchangeable potassium was comparatively low. The combined ash contained the highest concentrations of potassium (3.62) and phosphorus (0.56), exceeding the values recorded for T. diversifolia (3.45 and 0.52) and E. crassipes (2.75 and 0.42), respectively. All fertilizer treatments significantly enhanced growth relative to the control (\(\:p<0.001\)). The combined formulation produced the highest plant height (59.4 cm), leaf area (55.8 cm²), fresh weight (315.7 g plant⁻¹), and biomass (256.1 g plant⁻¹). These findings demonstrate that blended T. diversifolia and E. crassipes ash can serve as an effective, locally available, and environmentally sustainable foliar fertilizer for improving potato growth