• Most frequently limiting nutrient in cropping systems
• source of air and water quality degradation
• atmosphere composition - 78% N₂
• .03-.4% in soil - primarily in organic farms - very little in soils minerals
• 1-6% N in Plants

Draw out the map of nitorgen introduction

Name the major components

• immobilization
• mineralization
• Nitrification
• Leaching
• uptake
• Denitrification
• fixation
• volatilization

• Amino Acid
• Proteins
• Sugars
• Other(Complex unidentified organic compounds)

Nitrogen forms in Soil (inorganic)

• NH₄ (Ammonium)
• NO₃^-(Nitrate)
• NO₂^-(Nitrite)
• N₂O(nitrous oxide)
• NO(Nitric oxide)
• N₂(nitrogen gas)

• Plants absorb N as Nitrate (NO^-₃) and ammonium (NH⁺₄)
• Plant uptake of NO₃^- > NH⁺₄
•  NH⁺₄ preferred based on ENERGY balance
• NO₃^- preferred based on ELECTROCHEMICAL Balance
• NO₃^- + NH⁺₄ Can improve plant growth compared to NO₃^- or NH₄⁺ Can improve plant growth compared to NO₃^- or NH₄⁺ alone

Nitrogen Function in Plants

Amino Acid and Protein Production

DNA/RNA

Chlorophyll

Adequate Nitrogen

Excess Nitrogen

• Dark Green Color
• Vigorous Vegetative Growth
• Tillering
• High Photosynthetic activity

• Excessive vegetative growth/succulen-fat
• Increased susceptibility to disease
• Some crops are particularly sensitive to excess N - Potatoes, Sugar Beets, Cotton, Tabacco

• Yellowing, First appearing in older leaves. V-Shaped from leaf tip
• When Severe, older leaves die from leaf tip and along midrib

• Biological N₂ Fixation
• Atmospheric deposition
• Industrial N₂Fixation