plant nutrient interactions in soil environment
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Plant Nutrient Interactions in Soil EnvironmentTRANSCRIPT
Far West Washington Winter Conference 2011
Plant Nutrient Interactions in Soil Environment
Wesley HaunAgronomist Sales & Research
Far West Agribusiness AssociationWashington Crop Production Conf.Dec. 14, 2011
Far West Washington Winter Conference 2011
Sulfur Secondary nutrient essential for plant
growth. In some crops there can be similar
amounts of S as phosphorus (P). Critical in plant metabolic functions.
Component of some amino acids, vitamins, and enzymes.
Photosynthesis and seed formation.
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Sulfur Deficiency
Sulfur (S) continues to present challenges as to plant available soil SO4
2- and consistently correlate soil additions to predictable yield response.
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Soil Sulfur Deficiencies In U.S.
Sulfur deficiencies tend to be most prevalent in Great Plains, Northeast, California, and Southeast.
In Canada:Western areas
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Sulfur Sulfur is critical in conversion of nitrate
(NO3) S – deficiency N – deficiency N-S interaction & deficiency symptoms Similar in early growth stages Significantly different in later growth
stages
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Factors Influencing Soil Sulfur Availability
Low Organic Matter (OM)
Course textured soils (sandy)
Well drained soils
Low soil pH
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Factors Influencing Soil Sulfur Availability
SO42- adsorption to soil colloids
decrease as soil pH increases.
SO42- reacts w/OH ions of Fe & Al.
Liming soils decrease SO42- adsorbed
& increase amount of SO42- in soil
solution.
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Sulfur & Alkaline Soils
Availability of S in alkaline soils is function of amount of sulfate salts present (CaSO4) and OM in root zone.
Primary sources of S in alkaline soils are inorganic compounds.
Kaolinite clays retain more SO4 than Montmorilloite clays.
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Natural Sources SO42-
Organic Matter (OM)
Atmospheric Sulfur
Soil Minerals
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Atmospheric Deposition Significant amounts of S to growing
crop & soil
Sources:
Burning of gas, coal, oil, and anaerobic decomposition of OM
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Atmospheric Deposition
S enters the atmosphere as:
SO2
H2S
H2SO4
others
Nitrogen Mineralization and Nitrification
Soil Organic Matter
Manure
Rotting Plant Residues
+
Mineralization Nitrification
NH3
Ammonia
NH4+
Ammonium
NO2-
Nitrite
Oxygen
NO3-
NitrateBacteria
NitrosomonasNitrobacter
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Sulfur Cycle
Soil Organic S
H2S FeS
Elemental S
SulfateAerobic Conditions
Thiobacillus, Beggiatoa, Thiothrix
Anaerobic Conditions
Beggiatoa, Thiothrix
Leaching
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Sulfur Mineralization
Organic S Decay Products
Sulfates
Bacteria
Bacteria
(OM) (H2S, other organic sulfides)
(SO4 )
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Sulfur Mineralization Similar to Nitrogen (N)
Mineralization process.
Driven by correct Temperature
Moisture
Oxygen
Microbial activity
S Particle size
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Sulfur Oxidation
H2S + O2 H2O + S
S + O2 + H2O H2SO4
Oxidation of S results in H2SO4
Lowers soil pH
Bacteria
Bacteria
CaCO3 + H2SO4 CaSO4 + H2CO3
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Sulfur Cycle
Soil Organic S
H2S FeS
Elemental S
SulfateAerobic Conditions
Thiobacillus, Beggiatoa, Thiothrix
Anaerobic Conditions
Beggiatoa, Thiothrix
Leaching
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Effect of Soil Temperature on S Oxidation
0
10
20
30
40
50
60
70
80
Soil 1 Soil 2 Soil 3 Soil 4 Soil 5
SO4
Lev
el(p
pm)
Soils
41o F
69o F
80o F
SoilTemp.
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S Particle Size Affects Rate of Oxidation
Particle Size(mesh/inch)
2 weeks 4 weeks
20 – 40 5 14
40 – 80 15 36
80 - 120 36 68
120 - 170 61 81
230 80 82
% Sulphur Oxidized
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Oxidization of Elemental Sulphur
Elemental sulphur particle sizeThe smaller the particle size the faster the conversion to SO4
=
T90CR pastille T90CR drop of water T90CR fine powder
90 % Elemental Sulphur
10 % Dispersing Agent
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Soil pHRegulates plant nutrient availability. Influences micro-organism
population.Bacteria --- pH > 6.5Thiobacillus -- S oxidation
Fungi --- pH < 6.5N fixation --- pH > 6.0 P availability --- pH 6.5 – 7.5
Relationship Between Soil pH and Plant Nutrient Availability
Adapted from Truog, 1946. SSAP 11:305-308.
4 5 6 7 8 9 10
Nitrogen
MolybdenumCopper and Zinc
ManganeseIron
MagnesiumCalcium
SulfurPotassiumPhosphorus
Boron
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Effect of Soil pH on Phosphorus Availability
Rel
ativ
e P
Fixa
tion
In S
oil
VeryHigh
4 5 6 7 8
High
Medium
Low
GreatestFixation
HighFixation
MediumFixation
Range For HighestP Availability
FixationBy
Iron FixationDue To
Aluminum
FixationBy Calcium
Soil pH
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Sulfur Uptake by Plants
SO42-
Is not pH sensitive
Relatively insensitive to high SO4
2- concentrations in soil
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Croplbs SO4
2-
/unitYieldbu/Ac
Uptakelbs/Ac SO4
2-
Wheat 0.25 40 10.0
Sugar Beets 1.5 30 tons/Ac 45.0
Alfalfa
Potatoes
Corn
5
0.04
0.163
3.5 tons/Ac
400 cwt/Ac
140
18
17
23
Sulfur Uptake by Crop
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Sulfur Deficiency in Plant Best Method to Diagnose Plant tissue analysisSoil sample
Sulfur conc. 0.2 – 0.5% in plant tissue S deficiency NO3 accumulationBalancing S & N nutrition is important
for plant & animal health.
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Sulphur ApplicationTimingFallSpring Soil TemperatureOptimum range 75 – 85o F
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Sulphur ApplicationProduct SuggestionsTiger 90CR90% Sulphur
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Sulfur & Other Nutrient Interactions
Optimum S & K levels enhance Zn Uptake Fazili et al (2008) lack of S limits N use
efficiency Kowalenko & Lowe (1975) – high N:S ratio
decreased S mineralization optimum ratio at 7:1
Excess SO4 can reduce uptake of NO3 & MoO4 Excess NO3 can reduce uptake of SO4 S can reduce Cu toxicity w/Cu – S complexes
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Soil Sulfur determination compounded by several factors: Soil Sulfur. (OM, Minerals) Sulfur in precipitation. (SO4
2-) Atmospheric Sulfur. (SO2) Sulfur in soil/crop amendments.
(manure, fertilizer)
Soil Testing for Sulfur
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Soil Testing for SulfurCollection patternFactors that influence TopographySoil TypeCrop HistoryManure applications
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Soil Testing for Sulfur
Collect samples from root zone. 0 - 12 inches deep.
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Plant Tissue Sampling Procedures
Appropriate plant tissue. Seedlings – whole plant Mature plants – leaf/stems
Same stage of development. Soil samples w/complete
analysis.
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Tissue Sample Collection Most recent mature leaves just below
growing point on main stems. Select material without soil particles. DO NOT wash. Do not select dead/deteriorated material. Collect samples ASAP after symptoms
appear.
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Sulphur in AlfalfaSoil Test < 8 ppmPlant tissue test < 0.20%Apply:50 lbs/ac NH4SO4 or K2SO4
75lbs T90CR
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Sulfur Deficiency in Corn
Soil test value < 8 ppmPlant tissue value < 0.20%Apply:20 – 30 lbs/Ac sulfur
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Sulphur Deficiency in Potatoes
Soil test value < 7 ppmPlant tissue value < 0.20%Apply:10 – 20 lbs/Ac S
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Sulphur Deficiency in Sugar beets
Photos: Univ. of Cal - Davis
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Sulphur in Sugar Beets
Sulphur should not be limitingS is constituent of 3 amino acids
and critical in protein synthesisSoil test < 10 ppm in top 12 inchesApply 30 – 40 lbs/Ac S
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Sulphur in Sugar Beets
Interacts w/N & both nutrients effectiveness is improved.Enhances sugar quality.
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Sulfur Deficiency in Wheat
Soil test value < 8 ppmPlant tissue value < 0.20%Apply:20 – 30 lbs/Ac S
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SummarySulphur is an essential nutrient for plant
growth.Plant sulphur deficiencies are more
prevalent.Sulphur mineralization is similar to
nitrogen mineralization process.Primary crops grown in PNW
have relative high demand for sulphur.