How Calcium Cyanamide (Lime Nitrogen) Enhances Soil Fertility and Crop Health

Introduction to Calcium Cyanamide
Calcium cyanamide, also known as lime nitrogen, is an inorganic compound primarily used as a nitrogenous fertilizer and soil amendment. It contains both nitrogen and calcium and offers multiple agronomic benefits, including weed suppression, soil disinfection, and pest control. With the chemical formula CaCN₂, it has been used in agriculture since the early 20th century.

Chemical Properties and Mode of Action
Calcium cyanamide is a grayish powder formed by reacting calcium carbide with nitrogen at high temperatures. When applied to moist soil, it hydrolyzes into calcium carbonate and cyanamide. Cyanamide then decomposes into urea and ammonia, gradually releasing nitrogen in a plant-available form. This slow-release mechanism improves nitrogen use efficiency and reduces leaching losses.

Key Agricultural Applications

1. Nitrogen Fertilizer:
   It provides a stable and prolonged nitrogen supply, ideal for cereals, root vegetables, and oilseed crops.

2. Soil Conditioner:
   By raising soil pH and improving structure, it benefits acidic or compacted soils.

3. Weed and Pest Control:
   It acts as a mild herbicide and nematicide, suppressing weed seeds, soil-borne pathogens, and harmful insects when applied before planting.

4. Disinfectant:
   Calcium cyanamide sterilizes the soil surface, reducing disease pressure in intensive cropping systems.

Advantages of Using Calcium Cyanamide

• Slow-release nitrogen: Reduces nitrate leaching and enhances efficiency.

• Multifunctional use: Fertilizer, soil disinfectant, and weed controller.

• Improves soil health: Enhances structure and microbial balance.

• Reduces pests and diseases: Especially effective against nematodes and damping-off fungi.

Application Guidelines

• Apply 10–20 days before sowing or planting to allow decomposition.

• Incorporate into moist soil and irrigate if necessary to speed up reaction.

• Avoid contact with seedlings or young roots as it may cause phytotoxicity.

• Typical rates range from 300 to 500 kg/ha, depending on crop and soil type.

Safety and Environmental Considerations
Calcium cyanamide should be handled with care due to its alkaline and caustic nature. Protective clothing and gloves are recommended during handling. It must not be applied near water sources, as its byproducts can be harmful to aquatic life. Proper timing and incorporation into soil minimize environmental risks.

Limitations and Precautions

• Phytotoxic if used improperly: Needs a waiting period before sowing.

• Not suitable for alkaline soils: Can increase pH excessively.

• Corrosive to equipment: Clean machinery after use.

• Requires careful storage: Must be kept dry and away from acids.

FAQ About Calcium Cyanamide (Lime Nitrogen)

Q1: Is calcium cyanamide the same as urea?
No, although both provide nitrogen, calcium cyanamide also acts as a soil amendment and pest suppressor, while urea is solely a nitrogen fertilizer.

Q2: Can I plant immediately after application?
No. Wait 10–20 days after applying to allow it to decompose and avoid crop damage.

Q3: What crops benefit most from calcium cyanamide?
Crops like cabbage, onions, carrots, and potatoes respond well, especially when soil disinfection is needed.

Q4: Is it harmful to beneficial soil organisms?
When used correctly, it temporarily affects some microbes but eventually improves microbial balance as soil conditions improve.

Q5: Can calcium cyanamide replace chemical pesticides?
While it offers some control over soil pests and diseases, it is not a full replacement for targeted pesticide use.