1, nitrate is negatively charged and is not easily adsorbed by negatively charged soil colloid. Ammonium ions are positively charged and easily adsorbed by the soil, becoming fixed ammonium ions not only on the soil surface but also in the crystals of clay minerals. Nitrate nitrogen mainly exists in soil solution, with strong fluidity, easy to be absorbed and utilized by plants, and easy to be lost with rainwater.
2. Ammonium nitrogen is mainly adsorbed and fixed on the surface of soil colloid and colloid lattice, which has poor fluidity and is more easily wrapped by soil. Secondly, different forms of nitrogen will be transformed into each other in soil. Under suitable conditions of temperature, moisture and ventilation, urea is hydrolyzed to ammonium nitrogen by soil microorganisms and enzymes, and ammonium nitrogen is oxidized to nitrate nitrogen. The transformation of urea and ammonium nitrogen is slow in early spring and low temperature season, and fast in summer and high temperature season.
3. Nitrate nitrogen is often more than ammonium nitrogen in dryland soil, but less in paddy soil. Third, the soil moisture is too high. Under the condition of poor ventilation and fresh organic matter, nitrate nitrogen can be reduced to nitrous oxide, nitric oxide and nitrogen under the action of microorganisms, and this denitrification is one of the main ways of nitrate nitrogen loss.
4. The main way of nitrate nitrogen loss in soil is ammonia volatilization. Therefore, nitrate nitrogen fertilizer is suitable for cold regions and seasons. It can be applied in dry land by stages, and the fertilizer efficiency is fast and obvious, but it is not suitable for high temperature and rainy paddy fields. Ammonium nitrogen fertilizer is suitable for paddy field and dry land, but it is suitable for soil surface or paddy field, and ammonia volatilization loss is large.