Urea is the most concentrated solid nitrogenous fertilizer. It contains 46 per cent nitrogen. It is a white crystalline substance readily soluble in water. It is suitable for most crops and can be applied to all soils.
It is recommended both for soil and foliar application. It can be applied at sowing and or for top-dressing. Urea sprays are readily absorbed by plants. In case of foliar application the dasage is 10 gram/liter of water.
However, it absorbs moisture from the atmosphere. Therefore, it has to be kept in moisture proof containers.
Ammonium Sulphate is one of the oldest ammoniacal nitrogen fertilizers. It contains 20.6 per cent of nitrogen and 23.0 per cent of sulphur. It is a white salt completely soluble in water.
The nitrogen fraction in the fertilizer is present in the ammonium form. So ammonium sulfate is frequently used in flooded soils for rice production, where nitrate-based fertilizers are a poor choice due to denitrification losses.
It can be applied before sowing, at the time of sowing or as a top-dressing to the growing crop. However, ammonium sulfate has an acidifying effect in soil. Hence, it is not recommended for continuous use in acid soils.
It is easy to handle and it stores well under dry conditions. But during rainy season, it sometimes forms lumps.
Ammonium Sulphate Nitrate
Ammonium Sulphate Nitrate contains 26 per cent nitrogen, three fourths of it in the ammoniacal form and the rest as nitrate nitrogen. In addition to nitrogen it contains 12 per cent sulphur. It is a mixture of ammonium nitrate and ammonium sulphate.
It is available in white crystalline form or as dirty-white granules. It is readily soluble in water and is very quick-acting. Its keeping quality is good and it is useful for all crops.
Calcium ammonium nitrate (CAN)
Calcium ammonium nitrate is a fine free-flowing, light brown or grey granular fertilizer, containing 25 per cent of nitrogen. It is commercially prepared from ammonium nitrate and ground limestone.
It is almost neutral and can be safely applied even to acid soils. Half of this total nitrogen is in the ammoniacal form and half is in nitrate form.
Diamonnium Phosphate contains 18 per cent nitrogen and 46 per cent phosphorous. It is a good source of phosphorous and especially suited to cerial crops. It has good soluability in water.
Ammonium chloride contains 25 per cent nitrogen. It is more acidic than ammonim sulphate. It is not suitable to chlorine sensitive crops like tobacco and potato.