Influence of Tithonia diversifolia-Derived Organic Fertilizer and Planting Density on Potato Productivity in Batu, East Java

A transition toward organic fertilizers has increasingly been adopted as a key strategy to support sustainable agriculture, particularly in highland farming systems.In Sumber Brantas Village, Batu City, East Java-one of Indonesia's major highland potato-producing regions-potato (Solanum tuberosum) cultivation plays a critical role due to its high market value, adaptability to altitude, and importance as a carbohydrate source.This study investigated the effects of Tithonia diversifolia-derived organic fertilizer and varying plant densities on potato growth and productivity.Four fertilizer application rates (0, 120, 175, and 230 kg N/ha) and three plant densities (35,000, 47,000, and 71,000 plants/ha) were evaluated using a randomized block design arranged in a split-plot layout.Results indicated that the application of Tithonia diversifolia organic fertilizer significantly enhanced plant height, tuber biomass, and nitrogen (N) uptake.The highest fertilizer dose (230 kg N/ha) was associated with a 25% increase in N absorption and a 28% improvement in tuber yield relative to the unfertilized control.However, plant density did not exert a statistically significant effect on measured agronomic parameters.These findings underscore the agronomic value of Tithonia diversifolia as an organic fertilizer capable of improving nutrient use efficiency and tuber productivity under highland cultivation conditions.The results support the integration of this bioresource into sustainable nutrient management strategies for potato production, particularly in regions where agroecological conditions favor organic inputs.