Balanced Bokashi and NPK Fertilizer Strategy Restores Indonesian Sweet Corn Yields and Maximizes Sweetness

Gloria Florensia Br Surbakti Jumat, Juli 17, 2026
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FORMOSA NEWS

A field study conducted from January 2025 to May 2025 has established a precise fertilization protocol that significantly boosts the growth and quality of sweet corn (Zea mays saccharata Sturt). The research was carried out by Nunuk Helilusiatiningsih, Ahmad Sholeh Habibi Ibnu Rosyid, and Eva Febriana from the Universitas Islam Kadiri. Published in June 2026, the investigation details how an optimal combination of organic bokashi and inorganic NPK fertilizers can maximize stem development, cob weight, and sugar content. These findings offer a scalable agricultural strategy to counter recent declines in national corn production by optimizing soil fertility.

The Challenge of Declining Sweet Corn Yields

Sweet corn is an increasingly popular vegetable commodity across Indonesia and wider Asian markets due to its high caloric value and distinctively sweet taste. Despite high consumer demand, domestic production has struggled to keep pace. According to Statistics Indonesia data cited in the study, national shelled corn production experienced a notable downturn in 2023, with harvested areas shrinking by roughly 10.03 percent compared to the previous year.

A primary obstacle preventing farmers from achieving optimal crop productivity is unbalanced soil nutrient management, which frequently leaves agricultural land deficient in vital macro and micronutrients. Utilizing organic materials like bokashi fertilizer—a fermented organic matter—helps build up microbial diversity and nutrient availability in the soil. However, to sustain intensive crop cycles, farmers must balance organic interventions with structural inorganic fertilizers like NPK, which deliver essential nitrogen, phosphorus, and potassium to support stable crop development.

Methodology: Testing Fertilizer Combinations

The researchers conducted field experiments on a sandy clay topography situated in Ringinsari Hamlet, Padangan Village, Kediri Regency. The experimental site sat at an altitude of 86 meters above sea level. Over a five-month period, the team deployed a factorial Randomized Block Design (RBD) featuring the Talenta sweet corn variety to systematically evaluate two distinct agronomic factors:

  • Bokashi Fertilizer Doses: Evaluated at three organic baselines: 10 tons per hectare ($B1$), 15 tons per hectare ($B2$), and 20 tons per hectare ($B3$).
  • NPK Mutiara Fertilizer Doses: Evaluated across three agricultural baselines: 200 kilograms per hectare ($N1$), 300 kilograms per hectare ($N2$), and 400 kilograms per hectare ($N3$).

The resulting nine treatment combinations allowed the researchers to isolate how different fertilizer ratios altered vegetative markers—such as plant height, stem diameter, and leaf count—alongside generative yield metrics, including cob weight and sweetness levels measured via a Brix refractometer.

Key Findings: The 15:300 Optimal Blueprint

The statistical analysis revealed that sweet corn responds uniquely to isolated and combined fertilizer applications depending on the growth stage.

  • Vegetative Synergy: A clear dual interaction emerged between bokashi and NPK regarding early vegetative growth. The combined treatment of 15 tons per hectare of bokashi paired with 300 kilograms per hectare of NPK ($B2N2$) generated the highest structural outcomes, yielding an average plant height of 22.72 centimeters at 14 days after planting and an optimal stem diameter of 0.97 centimeters during peak growth observations.
  • Yield Independence: In contrast to early vegetative growth, final crop production metrics were driven independently by the NPK dosage. The 300 kilograms per hectare NPK application ($N2$) proved to be the absolute peak threshold, producing the heaviest ears of corn, averaging 399.6 grams with husks and 297.78 grams without husks.
  • Peak Sweetness: The sugar profile of the kernels was highly sensitive to potassium availability from the NPK fertilizer. The 300 kilograms per hectare NPK dose generated the highest overall sweetness level, reaching 10.67 Brix. Increasing the chemical fertilizer to 400 kilograms per hectare yielded no further statistical benefit, indicating a point of diminishing returns.

Implications and Real-World Impact

These insights provide clear, actionable guidance for agricultural communities, commercial growers, and regional policymakers aiming to secure food supplies. By demonstrating that a balanced approach using 15 tons of organic bokashi and 300 kilograms of NPK per hectare yields optimal structural results, the study shows how farmers can move away from over-fertilization. This balanced strategy prevents chemical runoff, minimizes input costs, and maintains structural soil health through organic matter while keeping crop yields high. Ultimately, delivering heavier, sweeter corn directly improves profitability for local farmers satisfying market demands.

Expert Commentary

"The addition of bokashi and NPK nutrients is highly effective for fulfilling the soil profiles required during crucial plant growth phases," noted the research team from Universitas Islam Kadiri. "An adequate nutrient supply during the photosynthesis process maximizes the photosynthate levels that sweet corn utilizes to form its cobs and seeds, while potassium ensures optimal sugar translocation directly to the ear."

Author Profiles

  • Nunuk Helilusiatiningsih is a faculty researcher at Universitas Islam Kadiri, holding an advanced academic degree and specializing in crop production, sustainable soil management, and agronomic optimization.
  • Ahmad Sholeh Habibi Ibnu Rosyid is an agricultural researcher affiliated with Universitas Islam Kadiri, focusing on fertilizer interactions, field trial designs, and crop cultivation metrics.
  • Eva Febriana is an agronomy specialist at Universitas Islam Kadiri, focused on evaluating vegetable crop responses to organic soil treatments and intensive cultivation practices.

Source

Gloria Florensia Br Surbakti

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