Introduction
Table of Contents
In early August, both Arabica and Robusta coffee require targeted fertilization to ensure beans develop properly, ripen evenly, and maintain their signature aroma and flavor. Proper nutrient management during this stage helps avoid shriveled beans and supports high-quality coffee production.
Fertilization for Arabica Coffee
Purpose
At the final stage of fruit development, supplementary fertilization helps Arabica beans become firm, brightly colored, and evenly ripened, enhancing flavor and preventing shriveling.
Recommended Fertilizers
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Root-applied: NPK (12-7-17 + TE) at 300 kg/ha or 200 kg/ha potassium nitrate (KNO₃) as an alternative.
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Foliar feeding: Spray NPK (12-0-40 + 3Ca) or HK 7-5-44 twice before harvest, with a 7-day interval. The final application must be at least 10 days before harvest.
Fertilization for Robusta Coffee
Purpose
For Robusta, the objective is to increase fruit weight and ensure high bean quality.
Importance of Organic Matter
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Apply organic fertilizer in August or by early September at the latest, ideally together with mineral fertilizers.
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Application rates depend on fertilizer quality:
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Medium quality (20–25% organic matter, total NPK < 6%): 10–15 kg/tree
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High quality (>30% organic matter, total NPK > 8%): 3–5 kg/tree
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Recommended brands: Quế Lâm, Humix, or similar high-quality organic fertilizers.
Mineral Fertilizer Selection Based on Foliage
If Leaves Are Pale Green and Thin
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Lower leaves turning yellow indicate nutrient deficiency.
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Apply NPK (16-8-16 + 13S + TE) or NPK (16-8-18 + 7S + TE) at 600–800 kg/ha.
If Foliage Is Bright Green and Leaves Are Thick
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Use NPK (12-7-17 + TE) at 600–800 kg/ha.
Using Single-Nutrient Fertilizers
Apply the following combination:
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300 kg/ha ammonium sulfate (SA) + 175 kg/ha urea
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225 kg/ha potassium chloride (KCl)
⚠️ Important Balance:
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Do not use 100% ammonium sulfate—excess sulfur (S) can harm plants.
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Do not use only urea, as this leads to sulfur deficiency, and sulfur is critical for the coffee’s distinctive aroma.
Alternative Option
Combine 300 kg/ha KNO₃ + 200 kg/ha calcium nitrate [Ca(NO₃)₂] + 300 kg/ha SA during the final fruiting stage.
Foliar Fertilizer Recommendations
If conditions allow, spray foliar fertilizers rich in:
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Nitrogen (N)
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Potassium (K)
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Calcium (Ca)
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Magnesium (Mg)
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Zinc (Zn)
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Boron (B)
These nutrients will boost yield and enhance the quality and flavor of the coffee beans.
Conclusion
Applying the right combination of organic and mineral fertilizers in August is key to high-quality Arabica and Robusta beans. Timely nutrient management ensures even ripening, stronger flavor, and premium-grade coffee for both domestic and export markets.