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      3. Nitrogen nutrition

        What are the factors that affect the content of nitrogen in soil?

        Soil organicmatter content, soil texture, soil tillage and utilization methods, etc.


         What is soil alkali hydrolysable nitrogen?

        Soil alkali hydrolysable nitrogen can be used as an indicator of soil nitrogen supplying capacity, including soil inorganic nitrogen, water soluble organic nitrogen and hydrolysable organic nitrogen.


         What are the main form of nitrogen absorbed by plants?

        Ammonium nitrogen(NH4-N), nitrate nitrogen (NO3-N) and acylammonium nitrogen, a small amount of other low molecular state organic nitrogen.


         What are the common nitrogen fertilizer?

        1, Ammonium nitrogen fertilizer: ammonium phosphate, ammonium sulfate, ammonium chloride,ammonium bicarbonate and so on.

        2, Nitrate nitrogen fertilizer: ammonium nitrate, potassium nitrate, calcium nitrate etc.

        3, Amide nitrogen fertilizer: urea, urea sulfate, urea phosphate and so on.

        4, Slow-releasenitrogen fertilizer: urea form aldehyde, Urea acetaldehyde etc.


         What are the nutritional functions of nitrogen?

        1, nitrogen is the major component of protein.

        2, nitrogen is the major component of nucleic acid.

        3, nitrogen is a component of chlorophyll.

        4, nitrogen is a component of many enzymes.

        5, nitrogen is a component of many vitamins and hormones.


         What are the ways of soil nitrogen loss?

        The losses of soil nitrogen include denitrification, NO3-N loss, volatilization of NH4-N and so on.


         What are the typical symptoms of the nitrogen deficiency in plants?

        1, The crop leaves appear pale green or yellow.

        2, The growth of the plant was stunted and short and thin, and the leaves were thin and small. The grass crops showed less tillers and slender stems, the dicotyledonous plants showed fewer branches.

        3, If the nitrogen deficiency is continued, the grass crops show short panicle, few grains per spike, the grain is not full, and premature senescence is easy to lead to decrease in yield.


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