fundamentals of soil nutrient dynamics - home page |...
TRANSCRIPT
NN--Rich Soils Grow NRich Soils Grow N--Rich PlantsRich Plants
0.8
1.0
1.2
1.4
1.6
1.8
0.0 0.2 0.4 0.6 0.8 1.0 1.2
Soil % N (0 – 10 cm)
Dou
glas
-Fir
Fo
liar
N (%
)
r2 = 0.71p < 0.001
Perakis et al. 2006
Nutritional Issues at NitrogenNutritional Issues at Nitrogen--Rich SitesRich Sites
• Phosphorus
• Sulfur
• Calcium, Magnesium, Potassium (base cations)
• Aluminum toxicity
• Micro-nutrients (Fe, Bo, Mn, Cu, Zn…)
• No deficiency
Phosphorus (P)
• Source: Apatite
• PO43- (H2PO4
- in forest soils)
• Chemically sticky (especially in Andic soils)
→ Iron (Fe3+), Aluminum (Al3+) – insoluble!
• Cycles readily through organic matter
Phosphorus Depletion
Geological time
Tota
l Soi
l Nut
rient
s
Walker and Syers 1976
Nitrogen Phosphorus
Phosphorus Forms in Soils
Geological time
Tota
l Soi
l P
Sequence of P forms
occluded
organic
soluble
Primarymineral
Walker and Syers 1976
Sulfur (S)
• Source: Pyrite and Gypsum, Seawater
• SO42-
• Somewhat chemically sticky
→ Iron, Aluminum, Calcium – soluble!
• Cycles readily through organic matter
Sulfur Inputs compared to Tree UptakeSulfur Inputs compared to Tree Uptake
Sources: NADP, Weathers et al. 1988, Binkley et al. 1992
WholeTree
Sulfu
r Fl
ux(k
g ha
-1yr
-1)
Precip& Fog
0
1
2
3
4
5
6
7
8
9
Bole &Branch
Bole Only
Base Cations - Ca, Mg, K
• Source: Many minerals, Seawater
• Ca2+, Mg2+, K+
• Very loosely held in soils
→ Ion exchange on organic matter and clays
• Very soluble and subject to leaching in acid soils
Base Cations in Soils
Soil Particle
Mg2+
Na+
Ca2+
Al3+
K+
H+
Cation exchange capacity
= sum of negative charges
Base saturation
% occupied by Ca+Mg+K+Na
Displacement series
H(Al3+)>H+>Ca2+>Mg2+>>K+=NH4
+>Na+
0
100
200
300
400
500
600
0 10 20 30 40 50 60 70 80
NO3- (µeq l-1)
Non
-sea
-sal
t cat
ions
(µeq
l-1)
Calcium (Ca2+)
Magnesium (Mg2+)
Sodium (Na+)
Potassium (K+)
Compton et al. 2003
Coupled Nitrate & Base Coupled Nitrate & Base CationCation LeachingLeaching
Soil % N (0-10cm)
Soil
Ca
& M
g(m
eq/1
00g)
Soil
0
2
4
6
8
10
0 0.4 0.8 1.2
Foliar Calcium trackssoil Calcium
Folia
r Ca
& M
g(%
)
0
0.2
0.4
0.6 Foliage
Perakis et al. 2006
High soil N drives low soil calcium & magnesium
Mg, Ca, K Requirements for Tree GrowthMg, Ca, K Requirements for Tree Growth
Sources: NADP, Weathers et al. 1988, Binkley et al. 1992
6
0
2
4
Precip. InputsBole Uptake
Nut
rien
t Flu
x(k
g ha
-1yr
-1)
Magnesium Calcium Potassium
Strontium as a tracer for Base Strontium as a tracer for Base CationsCations
• Sr immediately below Ca on periodic table
• Similar chemical and biological behavior to Calcium
• Natural 87Sr/86Sr variations reflect different sources (e.g. atmospheric inputs vs. bedrock weathering)
Exchangeable(0.7094)
Strontium isotopes trace Base Strontium isotopes trace Base CationCation sourcessources
0
10
20
30
40
50
60
700.705 0.710 0.715 0.720 0.725
Soil
Dep
th (c
m)
Seawater (0.7092) Weathering (0.7217)
Wood(0.7093)
87Sr / 86SrPerakis et al. 2006
Base Cation Deficiencies in Forests:Base Cation Deficiencies in Forests:
• Red spruce in north and southeastern USA
• Sugar maple in eastern USA and Canada
• Mixed northern hardwood forests in eastern USA
• Loblolly Pine in southern USA
• Norway spruce in Europe
• Coastal Oregon Douglas-fir ???
WrapWrap--up: Nutrition in Nup: Nutrition in N--Rich SitesRich Sites
• Phosphorus - sticky, long-term depletion, organic matter
• Sulfur - abundant in precipitation, somewhat sticky
• Calcium - sparse in precipitation, readily leached
• Aluminum toxicity - ???, can disguise Ca deficiency
• Micro-nutrients - ???
• No deficiency - ???
P-deficient
N-deficientP-sufficient
Foliar N:P ratios diagnose limitationsFoliar N:P ratios diagnose limitations
0
2
4
6
8
10
12
14
Folia
r N:P
(mas
s)
Elevation (m)
0 200 400 600 800
Nitrogen Cycle Dominates Forest Nutrition
Soil Organic Matter (SOM)
Plants
MicrobesNH4 NO3
Mineralization
Leaching to groundwater and
streams
NO, N2O NO, N2O, N2
N2
N2
DON
Immobilization
Foliar N:P ratios in coastal DouglasFoliar N:P ratios in coastal Douglas--FirFir
r2 = 0.45p = 0.001
0
2
4
6
8
10
12
14
0 200 400 600 800
Elevation (m)
Folia
r N:P
(mas
s)
N-limited
P-limited
Foliar N:P ratios in coastal DouglasFoliar N:P ratios in coastal Douglas--FirFir
r2 = 0.45p = 0.001
0
2
4
6
8
10
12
14
0 200 400 600 800
Elevation (m)
Folia
r N:P
(mas
s)
Elements > 0.1 % of plant dry mass are called macronutrients< 0.1 % are micronutrients
Element Principal function
carbon, hydrogen, oxygen component of all organic molecules
nitrogen (N) component of amino acids, proteins, chorophyll, nucleic acids
phosphorus (P) component of ATP, NADP, nucleic acids, phopholipids
potassium (K) ion/ osmotic balance, pH regulation, regulation of guard cell turgor
calcium (Ca) cell wall strengthening and functioning, ionic balance, membranepermeability
magnesium (Mg) component of chlorophyll, enzyme activiation
sulfur (S) component of amino acids, proteins
Much interest in SulfurMuch interest in Sulfur
Strand, Youngberg, Turner, Gessel, Edmonds …
Blake et al. 1988 – field experiment with N + S addition
”Because the field study does not provide a direct test of the N with S response …”
S was added with P, Ca, K Study stands responded to N alone – they were N deficientFertilization increased growth of low S stands
… decreased growth of high S stands