(1) The fate of nitrogen fertilizer
After the application of nitrogen fertilizer to the soil, there are three destinations. Some of the nitrogen is absorbed and utilized by the seasonal crops, some of which remain in the soil, and the other part is lost from the soil-crop system. Nitrogen remaining in the soil, although not contributing to the seasonal crops, can maintain the soil at least horizontally and vary for the crop varieties, environmental conditions, fertilization periods and methods. There is a competing relationship between them, the proportion of one going is increasing, and the proportion of the other two going is decreasing. Roughly speaking, crops are generally absorbed and utilized in the season of 30-50%, nitrogen loss can reach 20~60%, and soil residues are about 25~35%.
(2) Ways of loss of nitrogen fertilizer
Nitrogen loss is mainly caused by leaching, runoff and gaseous nitrogen. Gaseous nitrogen losses include ammonia volatilization and denitrification. The main products of denitrification are nitrogen and nitrous oxide gas.
In paddy soils, leaching losses are generally small, and nitrogen is mainly lost by nitrogen volatilization and denitrification. In the soil of dryland crops, in addition to the loss of gaseous nitrogen, the leaching loss can not be ignored, especially in areas with heavy rainfall and light soil texture. Heavy rain, heavy rain or improper irrigation may cause runoff loss from nitrogen fertilizer. Obviously, runoff losses in hilly areas are more severe than in plain areas. Afforestation, terrace construction, and proper irrigation all reduce soil and nitrogen loss.
Ammonia volatilization losses are prone to occur under alkaline conditions and, therefore, ammonia volatilization on calcareous or alkaline soils is much more severe than on acidic soils. Denitrification needs to be carried out under anaerobic conditions, so the denitrification loss in paddy fields is generally greater than in dry land. High temperature can promote ammonia volatilization and also facilitate denitrification.
Nitrogen loss and loss pathways are closely related to soil properties, farming and cultivation systems, and climatic and environmental conditions, and are also affected by agricultural measures. After clearing the way of nitrogen fertilizer loss, it is beneficial to take corresponding measures to reduce losses and increase nitrogen fertilizer utilization.
(3) Utilization rate of nitrogen fertilizer
There are two methods for determining the utilization rate of nitrogen fertilizer, the tracer method and the difference method. When using the tracer method to determine the nitrogen use efficiency, it is necessary to apply 15N to eliminate the fertilizer. The amount of 15N absorbed by the crop as a percentage of the amount of 15N applied is the nitrogen fertilizer utilization rate. When using the difference method to determine the nitrogen fertilizer utilization rate, it is only necessary to apply the general commercial nitrogen fertilizer, and at the same time, it is necessary to set a nitrogen-free zone, that is, a test zone where no nitrogen fertilizer is applied. The difference between the nitrogen uptake of the crop between the nitrogen-doping zone and the nitrogen-free zone is the percentage of nitrogen applied, which is the nitrogen fertilizer utilization rate measured by the difference method, and is usually called the apparent nitrogen fertilizer utilization rate.
Generally, the value of apparent nitrogen use efficiency is greater than the nitrogen use efficiency measured by the tracer method. According to different research and discussion objects, determine which method to use. For example, the apparent nitrogen fertilizer utilization rate should be determined when determining the amount of nitrogen fertilizer application, and the tracer method should be used to determine the direction of nitrogen fertilizer in the manufacturer.
After the application of nitrogen fertilizer to the soil, there are three destinations. Some of the nitrogen is absorbed and utilized by the seasonal crops, some of which remain in the soil, and the other part is lost from the soil-crop system. Nitrogen remaining in the soil, although not contributing to the seasonal crops, can maintain the soil at least horizontally and vary for the crop varieties, environmental conditions, fertilization periods and methods. There is a competing relationship between them, the proportion of one going is increasing, and the proportion of the other two going is decreasing. Roughly speaking, crops are generally absorbed and utilized in the season of 30-50%, nitrogen loss can reach 20~60%, and soil residues are about 25~35%.
(2) Ways of loss of nitrogen fertilizer
Nitrogen loss is mainly caused by leaching, runoff and gaseous nitrogen. Gaseous nitrogen losses include ammonia volatilization and denitrification. The main products of denitrification are nitrogen and nitrous oxide gas.
In paddy soils, leaching losses are generally small, and nitrogen is mainly lost by nitrogen volatilization and denitrification. In the soil of dryland crops, in addition to the loss of gaseous nitrogen, the leaching loss can not be ignored, especially in areas with heavy rainfall and light soil texture. Heavy rain, heavy rain or improper irrigation may cause runoff loss from nitrogen fertilizer. Obviously, runoff losses in hilly areas are more severe than in plain areas. Afforestation, terrace construction, and proper irrigation all reduce soil and nitrogen loss.
Ammonia volatilization losses are prone to occur under alkaline conditions and, therefore, ammonia volatilization on calcareous or alkaline soils is much more severe than on acidic soils. Denitrification needs to be carried out under anaerobic conditions, so the denitrification loss in paddy fields is generally greater than in dry land. High temperature can promote ammonia volatilization and also facilitate denitrification.
Nitrogen loss and loss pathways are closely related to soil properties, farming and cultivation systems, and climatic and environmental conditions, and are also affected by agricultural measures. After clearing the way of nitrogen fertilizer loss, it is beneficial to take corresponding measures to reduce losses and increase nitrogen fertilizer utilization.
(3) Utilization rate of nitrogen fertilizer
There are two methods for determining the utilization rate of nitrogen fertilizer, the tracer method and the difference method. When using the tracer method to determine the nitrogen use efficiency, it is necessary to apply 15N to eliminate the fertilizer. The amount of 15N absorbed by the crop as a percentage of the amount of 15N applied is the nitrogen fertilizer utilization rate. When using the difference method to determine the nitrogen fertilizer utilization rate, it is only necessary to apply the general commercial nitrogen fertilizer, and at the same time, it is necessary to set a nitrogen-free zone, that is, a test zone where no nitrogen fertilizer is applied. The difference between the nitrogen uptake of the crop between the nitrogen-doping zone and the nitrogen-free zone is the percentage of nitrogen applied, which is the nitrogen fertilizer utilization rate measured by the difference method, and is usually called the apparent nitrogen fertilizer utilization rate.
Generally, the value of apparent nitrogen use efficiency is greater than the nitrogen use efficiency measured by the tracer method. According to different research and discussion objects, determine which method to use. For example, the apparent nitrogen fertilizer utilization rate should be determined when determining the amount of nitrogen fertilizer application, and the tracer method should be used to determine the direction of nitrogen fertilizer in the manufacturer.
ã€Comment】 ã€Print this article】 ã€Close this page】 ã€Large, medium and small】
Parquet Wood Flooring,Walnut Herringbone Flooring,Walnut Parquet Flooring,Parquet Flooring
KelaiWood , https://www.kelaiwooden.com