As the 2011 coffee-care season begins, our center would like to share a recommended macronutrient fertilization protocol for Robusta coffee during its productive (business) phase. This procedure has already been applied successfully by many coffee farmers in different regions, bringing strong results such as lower costs, higher yields, and reduced pest and disease pressure.
Four Key Principles
Table of Contents
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Apply the right nutrient balance
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Apply at the right time of the season
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Apply in the correct manner
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Apply the correct nutrient amounts
Fertilizer Types and Timing
1. Annual Nutrient Requirement
Recommended N-P-K ratio: 3.2 – 1.2 – 3.5
Base amounts for farms yielding < 3.5 t/ha of green coffee beans in the previous crop:
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N: 320 kg
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P: 120 kg
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K: 350 kg
For each additional 1 t/ha of yield above 3.5 t:
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Add N: +70 kg, P: +25 kg, K: +75 kg.
Example: For a plot that produced 4.5 t/ha, apply
N: 320 + 70 = 390 kg, P: 120 + 25 = 145 kg, K: 350 + 75 = 425 kg of pure nutrients.
2. Application Schedule and Percentage of Annual Nutrients
| Application time | N (%) | P (%) | K (%) |
|---|---|---|---|
| 1st – Jan–Feb (irrigation period) | ~15 | 0 | 0 |
| 2nd – May (start of rainy season) | ~30 | 100 | 18 |
| 3rd – July (mid-rainy season) | ~40 | 0 | 35 |
| 4th – Sept–Oct (end of rainy season) | ~15 | 0 | 47 |
3. Converting to Commercial Fertilizers
Common sources:
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SA (ammonium sulfate): 22 % N
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Urea: 46 % N
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Muriate of Potash (KCl): 60 % K₂O
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Superphosphate: 14 % P₂O₅
Example for 4.5 t/ha yield (needs N = 390 kg, P = 145 kg, K = 425 kg of pure nutrients):
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SA: ~250 kg
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Urea: ~800 kg
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Superphosphate: ~1,050 kg
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KCl: ~800 kg
Split into four applications approximately as follows (kg/ha of product):
| Time | Nitrogen (SA + Urea) | Superphosphate | KCl |
|---|---|---|---|
| Jan–Feb | 250 | 0 | 0 |
| May | 280 | 1,050 | 150 |
| July | 380 | 0 | 280 |
| Sept–Oct | 140 | 0 | 370 |
Formula for converting nutrient requirement to fertilizer product:
Product needed (kg) = Pure nutrient needed (kg) × 100 ÷ % nutrient content
Example: For 145 kg of pure P with 14 % P₂O₅ superphosphate:
145 × 100 ÷ 14 ≈ 1,035 kg (round to ~1,050 kg).
Notes
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Adjust quantities according to actual tree vigor: weaker plants need lighter, more frequent applications.
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If soil pH is low (acidic), limit superphosphate and sulfate fertilizers.
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This is a concise guide; a detailed technical manual on intensive Robusta cultivation will be introduced in future updates.
End of summary.