Nitrogen is one of the three elements of plant nutrition and is the most important element determining the growth, yield and quality of crops. Nitrogen has important significance in agriculture, but it can increase the yield of grain and affect the quality of crops. It is reported that half of the world's grain is obtained by pouring nitrogen fertilizer. Nitrogen measurements can be made using a hand-held chlorophyll meter for non-invasive measurements, as well as soil analyzers for soil composition analysis. However, the use of the chlorophyll meter for measurement has the following drawbacks, and how to overcome the following drawbacks?
1. Each time a point on the blade is measured, so it is necessary to pass multiple tests (at least 30) to reduce the variation of the measurement, which means that it takes more time and strict measurement techniques to measure the position of the leaves. Perform certain control on the upper part, and select the upper end of the blade to measure, because the leaf chlorophyll content is susceptible to the influence of the single element in the soil;
2. The measurement results are greatly affected by factors such as variety, farming, environment, etc. The test indicators must be adjusted accordingly. The solution to this problem can be operated using the experimental control group through a piece of nitrogen that has not been applied. By comparing the plants, the above problems can be avoided;
3. In the wheat, corn and other gramineous crops, the SPAD reading increased with the increase of nitrogen application rate within a certain range of nitrogen application. However, when the nitrogen content exceeded a certain range, the SPAD reading was relatively stable and no longer increased. This means that it does not reflect the problem of excessive nitrogen application, which causes trouble in promoting the application. The reason for this problem is mainly because the excessive nitrogen plants can not be absorbed, and each plant has its own nitrogen demand. This problem is solved by the demand for nitrogen and the value of spad. Combine to calculate.
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