The risks of base fertilization are a critical factor determining the successful early establishment of any crop. Applying fertilizer before or during sowing can offer a strong advantage by supporting early growth. However, when fertilizer is placed directly on the seed or too close to it, or when soil factors are not properly evaluated, base fertilization can lead to serious problems. These risks become greater when the fertilizer rate, formula, or soil conditions have not been thoroughly assessed.
Below are the key agronomic elements that influence the safety and effectiveness of base fertilization, along with their relationship to its risks.
The main risks of base fertilization and their impact on crop growth
Understanding the conditions that intensify the risks of base fertilization helps growers avoid seed burn, weak emergence, and uneven plant establishment.
1. Soil type and how it affects the risks of base fertilization
Soil type heavily influences how fertilizer behaves around the seed zone.
- Heavy soils rich in clay or organic matter retain moisture and buffer fertilizer salts better.
- Sandy or light soils hold little water, allowing salts to accumulate near the seed much more quickly—significantly increasing the risks of base fertilization.
In soils with very low organic matter, electrical conductivity (EC) rises rapidly even after the first irrigation, creating a high-salinity environment that threatens seedling establishment.
2. Soil temperature and germination rate
Soil temperature determines how long the seed remains exposed to fertilizer salts.
- In warm soils, germination is rapid, reducing exposure time and the potential for damage.
- In cold soils, germination slows, prolonging the time the seed remains in a saline environment. This greatly increases the risks of base fertilization.
This effect is well documented in cereals, corn, and vegetables, where cold conditions often lead to higher rates of seed burn.
3. Soil salinity and fertilizer salt index
Natural soil salinity is a major factor influencing the risks of base fertilization. If soil EC is already high, adding a high-salt-index fertilizer can create conditions extremely unfavorable for germination.
When the soil already has an elevated EC:
- High-salt fertilizers make conditions worse.
- The seed zone becomes highly toxic.
- Emergence failure becomes much more likely.
Recommended practices include:
- Use fertilizers that have a lower salt index.
- Place the fertilizer away from the seed row.
- Reducing nitrogen or potassium inputs is important because these nutrients strongly increase electrical conductivity (EC).
For more guidance on proper fertilization practices, see “Base fertilization: A successful practice for your greenhouse.”
4. Post-planting weather conditions
The first 48–72 hours after planting are crucial:
- Rain or irrigation after sowing dissolves and disperses salts, greatly reducing the risks of base fertilization.
- Dry soil conditions cause salt accumulation near the seed, increasing the likelihood of seedling injury—especially in sandy soils.
The risks of base fertilization are more pronounced in spring and summer sowings, where high temperatures and evaporation intensify salt concentration.
5. Seed Quality and Germination Strength
Healthy, clean, and vigorous seeds have higher tolerance to adverse conditions. In contrast, seeds that are
- old harvest
- poorly stored
- mechanically damaged
tend to germinate slowly and unevenly. This prolonged exposure period increases the risks of base fertilization and often results in irregular crop establishment.
6. Plant stress and increased sensitivity
Any form of stress—drought, frost, disease, or insect pressure—reduces the plant’s tolerance to salinity.
When such conditions are expected, growers should:
- Lower fertilizer rates.
- Choose low-salt-index products.
- Avoid placing fertilizer directly on the seed row.
Plant stress intensifies the risks of base fertilization, as weakened seedlings are more vulnerable to salt injury.
7. Crop sensitivity and differentiated risk levels
Different crops respond differently to fertilizer placement:
- More tolerant: cereals (wheat, barley).
- Moderately sensitive: corn.
- Highly sensitive: cotton, vegetables.
Knowing a crop’s sensitivity level helps optimize fertilizer placement and minimize the risks of base fertilization.
For additional practical guidance, see “Greenhouse base fertilization: key points for successful planting.”
Conclusion
The risks of base fertilization arise not from a single factor but from the combined effects of soil type, climate, seed quality, and crop sensitivity. With proper assessment and careful application—correct rate, correct placement, correct fertilizer—base fertilization becomes a powerful tool for strong, uniform crop establishment.