Chemical fertilizers promote plant growth and are produced by a chemical process. Chemical fertilizers are less bulky than natural fertilizers such as manure or compost. There are many different types of chemical fertilizers and they come in powder, granular, liquid and gas forms.
Sodium nitrates contain 16 percent nitrogen and also are known as Chilates or Chilean nitrate. They are useful in soil that is acidic.
Ammonium sulphate comes in a white crystal form, similar to salt. It contains about 20 percent ammoniacal nitrogen and has an acidic effect on the soil.
Ammonium nitrate comes in a form similar to ammonium sulphate but it contains about 34 percent nitrogen. It acts quickly on the soil but can't be stored for very long.
This comes in a gas or liquid form and contains about 80 percent nitrogen. It is expensive and not generally suitable for home gardeners.
Ammonium chloride comes in a white crystal form and contains about 26 percent ammoniacal nitrogen. It acts similarly to ammonium sulphate.
Urea also comes in a white crystal form and has high concentrations of nitrogen. It acts quickly but water can quickly leech it away and it can't be stored for long periods.