Nitrogen Management - Agronomy - Kansas State University

91 Pages·2006·3.25 MB·English

by  Dale Leikam

NITROGEN
Nitrogen
• Air
– 78% Nitrogen
– 35,000 Tons/Acre
– Unavailable Form
• Nitrogen Fertilization
– Required in largest quantities (2-6% in plants)
– Most frequently deficient nutrient
– Main environmental concern is leaching to groundwater
• Forms Used by plants as
– NO - Nitrate
3
– NH + Ammonium
4
Functions of N in Plants
• Constituent of
– Proteins (6.25 x %N for crops other than wheat)
(5.7x%N for wheat)
– Chlorophyll
– Enzymes and other compounds
• Necessary for respiration, growth and reproduction
• Increased grain and forage yield of nonlegumes
• Improved root growth and H O use efficiency
2
Grain Sorghum N Uptake
Grain
Sorghum
Corn Nutrient Uptake And Dry
Matter Accumulation
100%
Potassium
80%
e Nitrogen
k
a
t
p
60%
U

l
a
ot Phosphorus Dry Matter
T
40%
f
o

%
20%
V 6 Tassel Maturity
Stage Of Growth
Nutrient Deficiency Symptoms
• Pale green - yellow
coloration. Starts at
leaf tip & down midrib.
• Slow growth, stunted
plants
• Mobile - starts on
lower leaves
• Reduced tillering
• Low Protein

N Deficiency in Legumes
• Check roots
for active
nodules
Nitrogen Cycle
Nitrogen Fixation
by Lightning
Soil Organic
Mi
n
Matter e
( r
A ali
m z
mo ati
nifi on Legume
c
ati Fixation of
o
n)
Atmospheric N
Animal Manures 2
Immobilization NH +
Crop Residues 4
Ammonium
I
m
m
o )
bili n
LoAsms Tmhornoiuag h zation (B atio
y c
Leaves Cro fi
p R ri
e t
si i
d N
u
e
s) ( Fertilizer
Nitrogen
Plant Uptake NO -
3
Nitrate
Removed by
Harvest
Removed by
Removed by Denitrification
Leaching
(Gaseous Loss from Wet Soils