This means that leaching of nitrates will take place much more easily in a sandy soil compared to a clay soil. Often, leaching is not a significant factor in heavy clay soils. Other factors that can affect nitrate leaching include amount of rainfall, amount of water use by plants and how much nitrate is present in the soil system. Impact on water quality Nitrate leaching can have a direct impact on water quality. Nitrate is very mobile and easily leaches with water.
Heavy rains can cause nitrates to leach downward in the soil below the root zone.
If depth to groundwater is shallow and the underlying soil is sandy, the potential for nitrates to enter groundwater is relatively high. However, if depth to groundwater is deep and the underlying soil is heavy clay, nitrates will not likely enter groundwater. In some cases where dense hardpans are present, nitrate leaching will not progress beyond the depth of the hardpan. Once nitrates get into the groundwater, the greatest concerns are for infants less than one year old and for young or pregnant animals. High levels of nitrates can be toxic to newborns, causing anoxia , or internal suffocation.