This document discusses macronutrients, specifically nitrogen. It covers: 1) Nitrogen occurs naturally in the atmosphere and can be fixed by microorganisms to forms plants can uptake. The preferred form depends on soil conditions and plant species. 2) Plants uptake nitrogen primarily as nitrate or ammonium via transporter proteins. Uptake is regulated by nitrogen levels to ensure efficient use. 3) Nitrogen functions include amino acids, proteins, nucleic acids, and other molecules. It is essential for plant growth, development, and biochemical processes.

1. Macronutrients
(Nitrogen)
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2. Nitrogen Occurrence
• Around 80% of our atmosphere consists of N (Karley & White, 2009).
• Both free living and symbiotic microorganisms are capable of fixing
atmospheric N2 in the form of NH4 + that can be directly taken up by
plants or converted into NO3 by nitrifying bacteria (Miller,2009).
• The preferred form in which N is taken up depends on soil conditions
and plant species (Clemens, 2005).
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3. • Plants adapted to low pH and reducing soil conditions tend to take
upNH4 +.
• At higher pH and in more aerobic soils,NO3 is the predominant form.
Both NO3 and NH4 + are highly mobile in the soil.
• By contrast, organic N compounds such as amino acids, are far less
mobile but there is growing evidence that these can also form
important N sources. (Miller & cramer, 2008)
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4. Uptake of Nitrogen
• Multiple uptake systems contribute to N uptake in plant roots.
• Arabidopsis, which primarily acquires N in the form of NO3 , contains
both high and low affinity transport systems that have affinities in the
micro molar and mili molar range.
• These NO3 transporters are encoded by genes from the NRT1 and
NRT2 families, respectively (Mitsuhashi et al., 2005).
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5. Nitrogen Uptake
(Sirijovski et al., 2009)
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6. Continues
• Some are induced by NO3 which provides a regulatory mechanism
that ensures increased uptake when substrate becomes available. NO3
uptake is also regulated by the plant N status, with glutamine acting as
negative feedback signal (Clemens, 2005)
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7. Functions of Nitrogen
• The foremost function of N is to provide amino groups in amino acids.
• N is essential in the biochemistry of many non-protein compounds
such as co-enzymes, photosynthetic pigments, secondary metabolites
and polyamines (Mitsuhashi et al., 2005).
• When in ample supply, NO3 is deposited in the vacuole where it
significantly contributes to turgor generation (Miller & cramer, 2008).
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8. • Nitrogen is one of the main component of the nucleotides (Clemens,
2005).
• Nucleotides form the constituents of nucleic acids but also have many
important functions in their own right such as in energy homeostasis,
signaling and protein regulation (Miller & cramer, 2008).
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10. Nitrogen Supply
• The release of mineral nitrogen from organic matter by soil
microorganisms.
• The higher the value for soil nitrogen supply the more likely it is that
the microorganisms in a soil will convert more organic nitrogen into
mineral nitrogen for plant uptake(Clemens, 2005).
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11. • The level of soil nitrogen supply that best balances the benefits and risks
varies depending on the clay content of soil.
• In sand soils, the best balance is achieved by a “Moderate” soil nitrogen
supply (25 – 50 mg-N/kg soil).
• In loam and clay soils “High” soil nitrogen supply is most suitable (50 – 75
and 75 – 125 mg-N/kg soil respectively).
(Clemens, 2005).
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12. Factors that Determine the Quantity of
Nitrogen Supplied by the Soil
• The quantity of nitrogen released from the soil organic matter
• The quantity of nitrogen released by decomposition of residues of the
previous crop
• Any nitrogen supplied by previous applications of organic waste
• Any nitrogen carried over from previous fertilizer applications.
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13. Nitrogen Availability at Specific pH
• Nitrogen (N), Potassium (K), and
Sulfer (S) are major plant nutrients
that appear to be less affected
directly by soil pH than many
others, but still are to some extent.
(Mitsuhashi et al., 2005).
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14. Utilization of Nitrogen by Various Crops
Crop N Required
Alfalfa 432 kg
Corn 180 kg
Soybeans 294 kg
Spring Wheat 176 kg
Winter Wheat 152 kg
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15. Nitrogen Required By Crops In ppm
CROP LB/ACRE NITROGEN N in ppm
Alfalfa 196 98
Ladino Clover 178 89
Sweet Clover 116 58
Red Clover 112 56
White Clover 103 51.6
Soybeans 98 49
Garden Peas 71 35.5
Peanuts 42 21
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16. MATERIAL % NITROGEN PER LB OF N N in kg N in ppm
Anhydrous
Ammonia
82% 1.80
0.816 0.408
Ammonia Sulfate 21% 5.20 2.359 0.1018
Urea 46% 1.83 0.830 0.415
Diammonium
Phosphate
18% 3.8
1.74 0.87
Urea-Form 38% 1.79 0.812 0.406
Monoammonium
Phosphate
10% 6.5
2.948 1.474
Ammonium Nitrate 33.5% 116 52.16 26.08
Nitrogen Solutions 19-49% 197-179 89.35 44.675
Calcium Nitrate 15% None None None
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17. NITROGEN REQUIRED BY PLANTS AT
VARIOUS STAGES
• Vegetative Stage
During this stage, your plant will feast on nitrogen as it develops the
stems, roots, and foliage to support energy production during flowering
phase.
• Flowering Stage
During this stage, your plants are transitioning from developing a lot of
leaves and stems and focusing their energy on buds, flowers, and fruit.
If you give your plants too much nitrogen during this phase you can
seriously impact its development.
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18. NITROGEN TOXICITY
• When there is large amount of nitrogen in the soil it causes the
nitrogen toxicity.
• It greatly effects the plants.
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19. Symptoms of Nitrogen Toxicity
• Extremely dark green leaves
• “Burning” of leaf tips, causing them to turn brown
• Some leaves turning yellow, due to abundance of nitrogen but lack of other
nutrients.
• Leaves are often dark green and in the early stages abundant with foliage.
• If excess is severe, leaves will dry and begin to fall off.
• Root system will remain under developed or deteriorate after time.
• Fruit and flower set will be inhibited or deformed.
• Stems becoming very stiff and brittle.
• Leaf tips may turn down, without signs of overwatering.
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21. Deficiency Symptoms
• The chlorophyll content of the plant leaves is reduced which results in pale
yellow color (Clemens, 2005).
• Older leaves turn completely yellow (Sirijovski et al., 2009)
• Flowering, fruitings, protein and starch contents are reduced(Mitsuhashi et
al., 2005).
• Reduction in protein results in stunted growth and dormant lateral buds
(Miller & cramer, 2008).
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22. • Smaller leaves, slow growth and a sparse profile.
• The stems and petioles turn a red/purple tinge.
• Lower leaves first appear pale green. The leaves then yellow and die
as the Nitrogen travels to support new growth. Eventually the
deficiency travels up the plant until only the new growth is green,
leaving the lowest leaves to yellow and wither. Lower leaves die from
the leaf tips inward(Miller & cramer, 2008).
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24. Labs
• Laboratories of Margaret Workman and Kimberly Frye - Depaul
University Chicago.
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25. References
• Ankele, E., Kindgren, P., Pesquet, E., & Strand, A. (2007). In vivo
visualization of Mg-ProtoporphyrinIX, a coordinator of photosynthetic
gene expression in the nucleus and the chloroplast. Plant Cell, 19,
1964-1979.
• Chen, Y. F., Wang, Y., & Wu, W. H. L. (2008). Membrane transporters
for nitrogen, phosphate and potassium uptake in plants. Journal of
Integrative Plant Biology, 50, 835-848.
• Hawkesford, M. J., & De, K. L. J. (2006). Managing nitrogen
metabolism in plants. Plant Cell Environment, 29, 382-395.
• Jamtgard, S., Nasholm, T., & Huss-Danell, K. (2008). Characteristics of
amino acid uptake in barley. Plant Soil, 302, 221-231.
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26. Thank you
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