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)

- --

-

-

--

--

-

-------- -------


- --

-

-

--

--

-

--------

Fe2+

Al3+

Mg2+

Ca2+Al3+

Mg2+

K+

Ca2+

K+

K+

K+


- --

-

-

--

--

-

-------- -------

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



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?



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

• A measure of acidity/alkalinity

pH


1 7 14

Acid NeutralBase

pH


• Which nutrients are basic, acid?

1 7 14

Acid NeutralBase

pH


• Which nutrients are basic, acid?– Basic – Ca2+, Mg2+, K+ , (Na+)

– Acid – H+, Al3+, Sulfur

1 7 14

Acid NeutralBase

pH


• 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


• 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


• 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


• 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


• Conifer needle litter reduces the soil pH over time

pH and trees



• pH < 4 aluminum toxicity

pH and trees

• Deciduous more tolerant of high pH than conifers are (Michigan jack pine)


• 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)


• 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?


• Salts already present (esp. W of Mo. Riv.)


• Salts already present (esp. W of Mo. Riv.)• Salts dissolve in water and move


• 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


• 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


• Control water table depth by:– Direct the drainage (tiles) – Deep-rooted perennials along ditches– Don’t summer fallow; use continuous cropping


• Shallow tillage


• Control water table depth by:– Direct the drainage (tiles)– Deep-rooted perennials along ditches– Don’t summer fallow; use continuous cropping


• Shallow tillage• Leave stubble nearby to capture moisture

which leaches salts out


Summary

• Soils provide nutrients to plants

Summary

• Soils provide nutrients to plants• Soil pH affects nutrient availability and tree

species selection

Summary


species selection• Many soils in ND are saline, with a limited

number of adapted tree species

Summary


species selection• Many soils in ND are saline, with a limited

number of adapted tree species• Managing saline soils means managing

water movement

Questions?

soils 102 – chemical properties. it’s more than just salt

Documents

ca2 mg2 h h

al3 mg2 h ca2 na ca2

al3 ca2 mg2

ca2 al3 na

al3 mg2 h ca2 na ca2

ca2 mg2 h po4

ca2 mg2 h no3

al3 fe2 al3 mg2 ca2