The findings are particularly relevant as farmers face growing pressure to increase crop yields while maintaining soil health. Excessive dependence on chemical fertilizers has long been associated with declining soil quality, prompting researchers and agricultural practitioners to explore integrated nutrient management systems that balance productivity with environmental sustainability.
Rising Demand for Kailan Calls for Smarter Farming Practices
Kailan, a leafy vegetable belonging to the cabbage family, has become increasingly popular because of its high nutritional value and strong market demand. Rich in vitamins, minerals, and dietary fiber, the crop contributes both to household nutrition and farmers' incomes.
Meeting this increasing demand, however, requires efficient cultivation techniques. One of the greatest challenges is maintaining soil fertility. While synthetic fertilizers provide nutrients rapidly, continuous application may gradually reduce soil quality and disrupt nutrient balance.
Liquid organic fertilizer (LOF) offers an environmentally friendly alternative by supplying macro- and micronutrients while improving soil conditions. Nevertheless, organic fertilizers generally release nutrients more slowly than inorganic fertilizers. Urea, on the other hand, supplies nitrogen quickly, making it highly effective for vegetative growth. The research explored whether combining these two fertilizer types could produce better agricultural outcomes than relying on either approach alone.
Large-Scale Field Experiment Evaluated Plant Performance
The research team conducted the experiment using a Randomized Block Design involving 288 kailan plants. Seeds were selected through soaking, germinated in seedling trays, and transplanted into polybags after 13 days.
Liquid organic fertilizer and urea treatments began one week after transplanting. Throughout the growing period, plants received regular irrigation, weekly nutrient applications, pest management, and routine maintenance before harvesting at approximately 42 to 45 days after planting.
To evaluate treatment effectiveness, the researchers analyzed plant performance using statistical analysis through ANOVA followed by Duncan's Multiple Range Test where significant differences were detected. The study measured four key indicators:
- Plant height
- Number of leaves
- Stem diameter
- Fresh plant weight at harvest
Combination Fertilization Improved Every Growth Indicator
The experiment demonstrated that liquid organic fertilizer and urea significantly influenced every measured growth parameter.
Among the notable results:
- The tallest kailan plants reached 42.75 cm under selected liquid organic fertilizer treatments.
- Urea application produced plants with an average maximum height of 42.67 cm.
- The highest leaf count reached 13.92 leaves per plant under liquid organic fertilizer treatments.
- Maximum stem diameter measured 1.83 cm with liquid organic fertilizer and 1.85 cm with urea.
- Fresh harvest weight reached 133.08 grams under one liquid organic fertilizer treatment, while the best treatment interaction produced 410 grams of combined fresh weight.
The researchers observed consistent improvements throughout the growing period, indicating that both fertilizers effectively supported vegetative development.
According to Ondo Hanatha Tondang and colleagues from Universitas Quality Berastagi, liquid organic fertilizer supplies essential macro- and micronutrients while helping improve soil conditions, whereas urea provides nitrogen that promotes chlorophyll formation, photosynthesis, and vigorous leaf and stem growth. Their findings suggest that combining both nutrient sources creates favorable conditions for healthier and more productive kailan cultivation.
Integrated Fertilization Supports Sustainable Agriculture
Rather than replacing inorganic fertilizers entirely, the study suggests that integrating liquid organic fertilizer with urea offers a more balanced fertilization strategy.
Organic fertilizer contributes beneficial microorganisms and gradually improves soil structure, helping maintain long-term soil fertility. Urea complements this by supplying readily available nitrogen needed during the plant's rapid vegetative stage.
This integrated approach may help reduce excessive dependence on chemical fertilizers while maintaining high crop productivity. For vegetable farmers, especially those cultivating kailan, the strategy represents an opportunity to improve both production efficiency and environmental sustainability.
Practical Benefits for Farmers and Agricultural Development
The research has several practical implications for agriculture in Indonesia and other regions where leafy vegetables are widely cultivated.
For farmers, the findings provide evidence-based guidance for selecting fertilization practices that increase crop performance while preserving soil quality.
For agricultural extension officers, universities, and policymakers, the study offers useful information for developing sustainable vegetable production programs that balance economic returns with environmental stewardship.
The researchers also recommend that future studies examine additional cultivation factors, including sunlight intensity, standardized polybag conditions, and irrigation management, to further optimize kailan production systems.
As global agriculture continues seeking solutions that improve productivity without degrading natural resources, integrated fertilization strategies such as those demonstrated in this study may become increasingly valuable for sustainable food production.
Author Profile
Ondo Hanatha Tondang is a researcher from Universitas Quality Berastagi specializing in crop cultivation and agricultural production systems. This study was conducted in collaboration with Roida Ervina Sinaga and Chaula Lutfia Saragih, also affiliated with Universitas Quality Berastagi. Their research focuses on improving horticultural production through effective and sustainable fertilization practices. The article does not specify the authors' academic degrees.
Source
Article Title: The Effect of Liquid Organic Fertilizer and Urea Fertilizer on the Growth and Production of Kailan (Brassica oleracea)
Authors: Ondo Hanatha Tondang, Roida Ervina Sinaga, Chaula Lutfia Saragih
University: Universitas Quality Berastagi, Indonesia
Journal: Indonesian Journal of Agriculture and Environmental Analytics (IJAEA)
Publication Year: 2026
Volume & Pages: Vol. 5, No. 2, pp. 475–484
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