Seed is the foundation of successful crop production. Using too little seed reduces plant population, while too much seed increases cost and causes overcrowding. Therefore, calculating the correct seed rate is essential for achieving optimum yield and efficient resource use.
This article explains how to calculate seed rate for different crops accurately, with simple methods and practical examples.
What Is Seed Rate?
Seed rate is the quantity of seed required to sow a unit area of land, usually expressed as:
- kg per hectare (kg/ha)
- kg per acre (kg/acre)
Correct seed rate ensures:
- Optimum plant population
- Uniform crop growth
- Efficient use of inputs
- Higher yield potential
Why Accurate Seed Rate Calculation Is Important
Accurate seed rate calculation helps farmers to:
- Avoid seed wastage
- Maintain proper spacing
- Reduce competition among plants
- Improve nutrient and water use efficiency
Factors Affecting Seed Rate
Seed rate varies depending on:
1. Crop Type
Cereals, pulses, oilseeds, and vegetables all have different seed size and spacing.
2. Spacing
Closer spacing requires more seed, wider spacing requires less seed.
3. Germination Percentage
Lower germination requires higher seed rate.
4. Seed Size and Weight
Bold seeds need more weight, small seeds need less.
5. Method of Sowing
Broadcasting requires more seed than line sowing or dibbling.
Method 1: Seed Rate Calculation Using Spacing
This method is commonly used for line-sown crops.
Step 1: Calculate Plant Population
Formula
Plant population per hectare = 10,000 ÷ (Row spacing × Plant spacing in meters)
Step 2: Calculate Required Seed Quantity
Formula
Seed rate (kg/ha) =(Plant population × 100-seed weight) ÷ (Germination % × 100)
Example
- Row spacing = 45 cm (0.45 m)
- Plant spacing = 20 cm (0.20 m)
- 100-seed weight = 5 g
- Germination = 90%
Plant population
10,000 ÷ (0.45 × 0.20) = 111,111 plants/ha
Seed rate
(111,111 × 5) ÷ (90 × 100)= 61.7 kg/ha
Method 2: Seed Rate Calculation Using Recommended Seed Rate
For many crops, agricultural universities provide standard seed rate values.
Example
| Crop | Seed Rate (kg/ha) |
|---|---|
| Rice (transplanted) | 30–35 |
| Wheat | 100–125 |
| Maize | 18–20 |
| Chickpea | 60–75 |
| Groundnut (bunch) | 125–150 |
These values may be adjusted based on:
- Seed quality
- Soil condition
- Sowing method
Method 3: Seed Rate Adjustment Based on Germination
Formula
Adjusted seed rate =Recommended seed rate × (100 ÷ Germination %)
Example
- Recommended seed rate = 100 kg/ha
- Germination = 85%
100 × (100 ÷ 85) = 117.6 kg/ha
Seed Rate per Acre Conversion
1 hectare = 2.47 acres
Seed rate per acre = Seed rate per hectare ÷ 2.47
Common Mistakes in Seed Rate Calculation
- Ignoring germination percentage
- Using blanket seed rates for all fields
- Over-seeding in broadcast sowing
- Not adjusting for seed size
How Agro Life Calculator Helps in Seed Rate Calculation
Agro Life Calculator provides:
- Seed rate calculators for different crops
- Automatic plant population calculation
- Germination-based adjustments
- Area unit conversion
This ensures accurate, quick, and error-free seed rate calculation.
Conclusion
Correct seed rate calculation is essential for uniform crop stand and higher productivity. By considering spacing, germination percentage, and crop type—or by using tools like Agro Life Calculator—farmers can avoid losses and maximize returns.
Accurate seed rate leads to healthy crops, efficient input use, and better yields.