Nitrate leaching from agriculture fields

Nitrate leaching is a naturally occurring process, it occurs when mobile nitrate from the mineral nitrogen pool is washed out of the root zone by runoff. The main form of nitrogen that is leached is nitrate (NO3). Other forms of nitrogen, such as ammonium (NH4+), generally do not leach. Nitrate is very mobile therefore it can be easily transported by water. Manures, decompose of plants and other organic materials, fertilisers are possible sources of nitrates. When it is within the root zone, there is no issue, but if it enters the groundwater and other freshwater areas, it becomes an environmental hazard