Q1: Which one of the following is used as a nitrogenous fertiliser, as a weed killer in the onion fields and for correcting acidic soils ?

ANS:D - Calcium cyanamide

Calcium cyanamide, often referred to simply as "cyanamide," is a chemical compound with the formula CaCN₂. It is a white, granular solid that is commercially available in different forms such as powder or granules. Calcium cyanamide has several uses:

1. Nitrogen Fertilizer: Calcium cyanamide is used as a slow-release nitrogen fertilizer. When applied to the soil, it undergoes hydrolysis to release ammonia and calcium carbonate. The ammonia then serves as a nitrogen source for plants, promoting their growth. Due to its slow-release properties, it provides a steady supply of nitrogen over an extended period, which can be beneficial for crop growth.
2. Weed Control: Calcium cyanamide also has herbicidal properties and can be used as a weed killer. When applied to the soil, it inhibits the germination of weed seeds and suppresses the growth of existing weeds. This makes it useful for weed control in various agricultural settings.
3. Soil Amendment: In addition to providing nitrogen, calcium cyanamide can also help to correct acidic soils. As it hydrolyzes in the soil, it releases calcium carbonate, which acts as a soil amendment to neutralize acidity and improve soil structure. This can be particularly beneficial in soils that are too acidic for optimal plant growth.