Soils 102 – Chemical properties. It’s more than just salt...
-
Upload
matilda-cox -
Category
Documents
-
view
214 -
download
0
Transcript of Soils 102 – Chemical properties. It’s more than just salt...
Soils 102 – Chemical properties
Soils 102 – Chemical properties
It’s more than just salt ...
Outline
• Introduction• Topics:
– Nutrients– pH– salinity/sodicity
• Practical matters• Summary
Introduction
• Chemical elements ...
Chemical elements
• Nitrogen– nitrate– ammonium
• Phosphorous• Potassium• Calcium• Magnesium• Aluminum• Sodium• Hydrogen
• N– NO3
-
– NH4+
• P (PO43-)
• K (K+)• Ca (Ca2+)• Mg (Mg2+)• Al (Al3+)• Na (Na+)• H (H+)
Introduction
• Chemical elements ... • Where are the nutrients, salts, etc.?
Mineral particle (sand, silt, clay)
- --
-
-
--
--
-
-------- -------
Mineral particle (sand, silt, clay)
- --
-
-
--
--
-
--------
Fe2+
Al3+
Mg2+
Ca2+Al3+
Mg2+
K+
Ca2+
K+
K+
K+
Mineral particle (sand, silt, clay)
- --
-
-
--
--
-
-------- -------
Mg2+H+H+K+Ca2+Al3+Na+K+Ca2+Mg2+H+H+K+Ca2+Al3+Na+K+Ca2+Mg2+H+
Mg2+
H+
Ca2+
Na+
Ca2+
H+
K+
Al3+
Fe2+
Al3+
Mg2+
Ca2+Al3+
Mg2+
K+
Ca2+
K+
K+
K+
Adsorbed to particle surface
Mineral particle (sand, silt, clay)
Mg2+H+H+K+Ca2+Al3+Na+K+Ca2+Mg2+H+H+K+Ca2+Al3+Na+K+Ca2+Mg2+H+
Mg2+
H+
Ca2+
Na+
Ca2+
H+
K+
Al3+
Mg2+
H+
Ca2+
Na+
Ca2+
H+
K+
Al3+
Adsorbed to particle surfaceAvailable in soil
water
- --
-
-
--
--
-
--------
Fe2+
Al3+
Mg2+
Ca2+Al3+
Mg2+
K+
Ca2+
K+
K+
K+
Nutrients
• How are nutrients held to the mineral soil?
Mineral particle (sand, silt, clay)
Mg2+H+H+K+Ca2+Al3+Na+K+Ca2+Mg2+H+H+K+Ca2+Al3+Na+K+Ca2+Mg2+H+
Mg2+
H+
Ca2+
Na+
Ca2+
H+
K+
Al3+
Mg2+
H+
Ca2+
Na+
Ca2+
H+
K+
Al3+
Available in soil water
- --
-
-
--
--
-
--------
Negative charges on particle surface
Adsorbed to particle surface
Nutrients
• How are nutrients held to the mineral soil?• Organic matter – another source
Mg2+H+NO3-K+Ca2+Al3+Na+K+Ca2+Mg2+H+PO4-K+Ca2+Al3+Na+K+Ca2+NO3-H+
Mg2+
H+
Ca2+
Na+
Ca2+
PO4-
K+
Al3+
Mg2+
H+
Ca2+
Na+
Ca2+
PO4-
K+
Al3+
-
-
-
--
-
---
-
-
--
-
+ + -
-
Organic matter
Mg2+H+NO3-K+Ca2+Al3+Na+K+Ca2+Mg2+H+PO4-K+Ca2+Al3+Na+K+Ca2+NO3-H+
Mg2+
H+
Ca2+
Na+
Ca2+
PO4-
K+
Al3+
Mg2+
H+
Ca2+
Na+
Ca2+
PO4-
K+
Al3+
-
-
-
--
-
---
-
-
-
--
--+
+
+ -
+
+
+
+
-
-
--
--
-
Ca2+Mg2+H+NO3-K+Ca2+Al3+Na+K+Ca2+Mg2+H+PO4-K+Ca2+Al3+Na+K+Ca2+NO3-H+
Mg2+
H+
Ca2+
Na+
Ca2+
PO4-
K+
Al3+
Mg2+
H+
Ca2+
Na+
Ca2+
PO4-
K+
Al3+
-
-
-
--
-
---
-
-
-
--
--
NH4+
K+
H+
Na+PO4-
Mg2+
+
+
+
NO3-
-
+
+
+
+
-
-
--
--
-
NO3-
K+
NO3-
NH4+
pH
pH
• A measure of acidity/alkalinity
pH
• A measure of acidity/alkalinity
1 7 14
Acid NeutralBase
pH
• A measure of acidity/alkalinity
• Which nutrients are basic, acid?
1 7 14
Acid NeutralBase
pH
• A measure of acidity/alkalinity
• Which nutrients are basic, acid?– Basic – Ca2+, Mg2+, K+ , (Na+)
– Acid – H+, Al3+, Sulfur
1 7 14
Acid NeutralBase
pH
• A measure of acidity/alkalinity
• Which nutrients are basic, acid?• Which of these predominate in the Plains?
1 7 14
Acid NeutralBase
Location H+, Al3+
Ca2+ Mg2+ K+ Na+
% % % % %
Hawaii 85 10 3 2 tr
New England
80 15 3 2 tr
Southeast 65 25 6 3 1
Lake States
45 35 13 5 2
S. Central 40 38 15 5 2
Midwest 30 43 18 6 3
Southwest --- 65 20 10 5
pH
• A measure of acidity/alkalinity
• Which nutrients are basic, acid?• Which of these predominate in the Plains?• Average pH of ND soils?
1 7 14
Acid NeutralBase
Soil pH levels, upland positions, non-manured sites, 1998. (Franzen, 1999)
pH
• A measure of acidity/alkalinity
• Which nutrients are basic, acid?• Which of these predominate in the Plains?• Average pH of ND soils?• How pH affects nutrient availability
1 7 14
Acid NeutralBase
pH
• A measure of acidity/alkalinity
• Which nutrients are basic, acid?• Which of these predominate in the Plains?• Average pH of ND soils?• How pH affects nutrient availability• How pH affects tree survival and growth
1 7 14
Acid NeutralBase
pH and trees
• Deciduous more tolerant of high pH than conifers are (Michigan jack pine example)
pH and trees
• Deciduous more tolerant of high pH than conifers are (Michigan jack pine example)
• Conifer needle litter reduces the soil pH over time
pH and trees
• Deciduous more tolerant of high pH than conifers are (Michigan jack pine example)
• Conifer needle litter reduces the soil pH over time
• pH < 4 aluminum toxicity
pH and trees
• Deciduous more tolerant of high pH than conifers are (Michigan jack pine)
• Conifer needle litter reduces the soil pH over time
• pH < 4 aluminum toxicity• Which conifers appropriate to high pH?
pH and trees
• Deciduous more tolerant of high pH than conifers are (Michigan jack pine)
• Conifer needle litter reduces the soil pH over time
• pH < 4 aluminum toxicity• Which conifers appropriate to high pH?
– Ponderosa pine– Rocky Mountain juniper– Eastern redcedar
Salinity
Salinity
• High soluble salt concentration
Salinity
• High soluble salt concentration• Not necessarily high sodium salts
Soluble salts
• NaCl• Na2SO4
• NaHCO
3
• Na2CO3
• MgCl2• MgSO4
• CaCl2
• Sodium chloride• Sodium sulfate• Sodium bicarbonate• Sodium carbonate• Magnesium chloride• Magnesium sulfate• Calcium chloride
How do saline soils (seeps) develop?
How do saline soils (seeps) develop?
• Salts already present (esp. W of Mo. Riv.)
How do saline soils (seeps) develop?
• Salts already present (esp. W of Mo. Riv.)• Salts dissolve in water and move
How do saline soils (seeps) develop?
• Salts already present (esp. W of Mo. Riv.)• Salts dissolve in water and move• Water evaporates, leaving concentrated
salts
Saline soils in Grand Forks County (Seelig, 2000)
Formation of saline seeps (Seelig, 2000)
Salinity
• High soluble salt concentration• Not necessarily high sodium salts• Measured by electrical conductivity (EC)
– Units are mmhos or dS/m
Salinity
• High soluble salt concentration• Not necessarily high sodium salts• Measured by electrical conductivity (EC)
– Units are mmhos or dS/m– NDSU soils lab recommendations:
• 0-1 Non-saline• 1-2 Very slightly saline• 2-4 Slightly saline• 4-6 Saline• >6 Strongly saline
0-1 1-2 2-4 4-6 >6NDSU:
NRCS: (S.E.)
Salt tolerant – Salt sensitive
Salt tolerant – Salt sensitive• sea-buckthorn (9)• silver buffaloberry (9)• silverberry (9)• Russian-olive (9)• green ash (9)• caragana (9) • skunkbush sumac (9)• junipers (9)• (lilac) (9)• (honeysuckle) (9)• (ponderosa pine)• (juneberry)• (chokecherry)
Salt tolerant – Salt sensitive• sea-buckthorn (9)• silver buffaloberry (9)• silverberry (9)• Russian-olive (9)• green ash (9)• caragana (9) • skunkbush sumac (9)• junipers (9)• (lilac) (9)• (honeysuckle) (9)• (ponderosa pine)• (juneberry)• (chokecherry)
• Sand cherry• Dogwood• Little-leaf linden• Hybrid poplar *• Black walnut• Manchurian apricot• (crabapple)• (American plum)
Salinity
• High soluble salt concentration• Not necessarily high sodium salts• Measured by electrical conductivity (EC)• Saline vs. sodic vs. saline-sodic
SoilCommon
pHElectrical
ConductivitySodium
adsorption ratio
Normal 6.5 – 7.2 <4 <13-15
Saline <8.5 >4 <13-15
Saline-sodic
<8.5 >4 >13-15
Sodic >8.5 <4 >13-15
Data from Brady, 1990
ND saline and sodic soils (Seelig, 2000)
Salinity
• High soluble salt concentration• Not necessarily high sodium salts• Measured by electrical conductivity (EC)• Saline vs. sodic vs. saline-sodic• Trees are more sensitive at germination,
or while they’re really getting established.
How to manage saline soils?
• Control water table depth by:– Direct the drainage (tiles)– Deep-rooted perennials along ditches– Don’t summer fallow; use continuous cropping
How to manage saline soils?
• Control water table depth by:– Direct the drainage (tiles)– Deep-rooted perennials along ditches – Don’t summer fallow; use continuous cropping
• Grow a salt-tolerant crop or green mulch on seeps
How to manage saline soils?
• Control water table depth by:– Direct the drainage (tiles) – Deep-rooted perennials along ditches– Don’t summer fallow; use continuous cropping
• Grow a salt-tolerant crop or green mulch on seeps
• Shallow tillage
How to manage saline soils?
• Control water table depth by:– Direct the drainage (tiles)– Deep-rooted perennials along ditches– Don’t summer fallow; use continuous cropping
• Grow a salt-tolerant crop or green mulch on seeps
• Shallow tillage• Leave stubble nearby to capture moisture
which leaches salts out
How to manage saline soils?
Summary
• Soils provide nutrients to plants
Summary
• Soils provide nutrients to plants• Soil pH affects nutrient availability and tree
species selection
Summary
• Soils provide nutrients to plants• Soil pH affects nutrient availability and tree
species selection• Many soils in ND are saline, with a limited
number of adapted tree species
Summary
• Soils provide nutrients to plants• Soil pH affects nutrient availability and tree
species selection• Many soils in ND are saline, with a limited
number of adapted tree species• Managing saline soils means managing
water movement
Questions?