Integrated use of potassium-enriched composts to enhance tomato yield and fertilizer efficiency in kitchen gardens

Potassium (K) value addition in composts is often overlooked, despite its critical role in enhancing tomato yield and quality for kitchen gardening. Over two years of pot experiments, Biochar Enriched Compost (BEC) and Value-Added Compost (VAC) were assessed as potential substitutes (25 to 75%) for inorganic K. Treatments comprised different combinations of BEC+SOP or VAC+SOP to evaluate their potential for improving crop performance. Results demonstrated that substituting 25 to 75% of inorganic K with BEC or VAC significantly improved fruits per plant (4-40%), plant biomass (4-12%), photosynthetic rate (2-33%), chlorophyll content (2-25%), water use efficiency (6-17%), biological yield (4-14%), and fruit yield (3-17%) compared with sole inorganic K application. Integrated use of BEC and SOP or VAC and SOP enhanced K recovery efficiency (24-81%), and K agronomic use efficiency (4-25%) over SOP alone. Fruit quality was also enhanced, with higher total soluble solids (46-64%), ascorbic acid (2-15%), lycopene content (2-97%), and fruit pulp (15-32%). VAC consistently outperformed BEC, suggesting that replacing 25% inorganic K with VAC or BEC optimize K utilization, yield, and quality. This study established a baseline for K value addition during composting of organic wastes to produce nutrient-rich compost for sustainable kitchen gardening of high-quality tomatoes.