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Soil Chemistry & Fertility

Unit 2.2 | Part 2 – 63

t figUre 2 .9 | the CARBoN CyCLe (ADAPteD FRom mIChIGAN StAte UNIVeRSIty exteNSIoN BULLetIN e-2646)

Lecture 2: Plant Nutrient Requirements & Nutrient Cycles

iii. Firing (burnt look) of tips and margins of leaves beginning with more mature leaves

iv. Low protein content of crops

c) Symptoms of nitrogen excess include:

i. Dark green, succulent, vegetative growth at the expense of seed production in grain
crops, the expense of fruit production in tomatoes and some tree crops, and the
expense of sugar content in beets

ii. Watery potatoes

iii. Frost damage if there is too much succulent growth when frost hits

iv. Weakened stems (lodging)

v. Delayed flowering or fruiting

vi. Boron or copper deficiency due to inhibited uptake of these nutrients

d) Forms of nitrogen in the soil

Nitrogen occurs in the soil in various forms:

i. Nitrogen gas in the soil air (N 2 )

ii. Nitrate (No 3 - )

iii. Nitrite (No 2 - )

iv. Ammonium (Nh 4 +)

v. Ammonia (Nh 3 )—a gaseous, transitory form

vi. In various other forms as part of complex organic molecules

Cathy Genetti Reinhard