This loss of soil or fertilizer nitrate through leaching is a serious factor only on sandy soils in high rainfall areas, or under irrigated conditions. Fine textured clay soils are able to hold more moisture and allow much less movement of water and nitrate down through the soil. On sandy soils, leaching can be minimized by using an ammonium form of fertilizer banded in the soil close to the time of seeding. On irrigated land, correct irrigation scheduling can help minimize leaching. Volatilization Nitrogen fertilizers containing urea or ammonium may also be lost through volatilization as an ammonia gas into the atmosphere.
Losses are greater from alkaline than from acid soils and from dry rather than wet soils.
Losses from sandy soils are usually greater than from heavier textured soils and are greater at higher temperatures than low. Greatest volatile losses can occur where there is just enough moisture to put the fertilizer into solution, but not enough to move it into the soil, followed by hot, dry, windy conditions. Losses due to ammonia volatilization can be eliminated or reduced to negligible amounts when the fertilizer is covered well by soil. Denitrification Nitrate can also be lost to the atmosphere through a process called denitrification. In this process, nitrate is converted to a gas by soil microorganisms.