Soil regulating functions

John Quinton Lancaster Environment Centre

1) Habitat for organisms

2) Nutrient cycling filter and buffer

3) Medium for plant growth

4) Water and climate regulation & carbon storage

5) Engineering medium

6) Physical and cultural heritage

7) Community – soils bring people together

Soil functions

• How much water in a soil profile?

Water storage and regulation

How much water is in the world’s soils?

Source USGS

Add Figure 5.12

• Clay soil holds more water than loam or sand.

• water is held much more tenaciously in the clay soil due to micropores,

• soil texture is important in water retention.

• Soil structure is also important. A well granulated soil higher water-holding capacity.

• Compacted soils, less capacity, more tenacity (pores smaller)

Water Content and Soil Water Potential

From Brady and Weil (2007)

Aggregates Peds

Antonio Jordán,

Antonio Jordán,

Why care about soil structure?

it is the plumbing system for the soil which controls • water flow • air flow

Carly Stevens

Carly Stevens

• Reduced infiltration

• Poorer structural condition

• Reduced surface roughness

What are the impact of compaction on soil structure?

rural urban

Alleviating soil compaction

Conventional tramline Disrupted tramline

Martyn Silgram ADAS

Soil as a regulator of water quality

As a water filter

Soil cycling

Atmosphere

Organic matter Mineral

Solution

Groundwater

Surface water

biota

What is the fate of soilwater?

The Phosphorus Cycle

Crop

harvest

Organic phosphorus

* Microbial

* Plant residue

* Humus

Leaching

(usually minor)

Soil solution

phosphorus

•HPO4-2

•H2PO4-1

Primary

minerals

(apatite)

Mineral

surfaces

(clays, Fe and

Al oxides,

carbonates)

Secondary

compounds

(CaP, FeP, MnP, AlP)

Runoff and

erosion

PLANTS

Plant

residues

Animal manures

and biosolids

Mineral

fertilizers

Atmospheric

deposition

Plant

uptake

Immobilisation

Mineralisation

PrecipitationDissolution

Weathering

Adsorption

Desorption

Component Loss from soilInput to soil

Below ground

Above ground

The Phosphorus Cycle

Crop

harvest

Crop

harvest

Organic phosphorus

* Microbial

* Plant residue

* Humus

Leaching

(usually minor)

Leaching

(usually minor)

Soil solution

phosphorus

•HPO4-2

•H2PO4-1

Primary

minerals

(apatite)

Mineral

surfaces

(clays, Fe and

Al oxides,

carbonates)

Secondary

compounds

(CaP, FeP, MnP, AlP)

Runoff and

erosion

PLANTS

Plant

residues

Plant

residues

Animal manures

and biosolids

Animal manures

and biosolids

Mineral

fertilizers

Mineral

fertilizers

Atmospheric

deposition

Atmospheric

deposition

Plant

uptake

Plant

uptake

Immobilisation

Mineralisation

PrecipitationDissolution

Weathering

Adsorption

Desorption

Component Loss from soilInput to soilComponent Loss from soilLoss from soilInput to soilInput to soil

Below ground

Above ground

Sims, J. T., Simard, R. R., & Joern, B. C. (1998). Phosphorus loss in agricultural drainage: Historical perspective and current research. Journal of Environmental Quality, 27(2), 277-293.

The soil N Cycle simplified

(From, Bardgett, 2005)

Goulding, K. (2000). Nitrate leaching from arable and horticultural land. Soil use and management, 16(s1), 145-151.

www.Rothamsted.ac.uk

www.balticdeal.eu

Mayer, P. M., Reynolds, S. K., McCutchen, M. D., & Canfield, T. J. (2007). Meta-analysis of nitrogen removal in riparian buffers. Journal of environmental quality, 36(4), 1172-1180.

Buffering of acidity

Krug, E. C., & Frink, C. R. (1983). Acid rain on acid soil: A new perspective. Science, 217(4610), 520-525.

Carbon storage and climate regulation

Global carbon cycle

Adapted from Brady and Weil (2008)

Soil 2400

Atmosphere 760

Oceans and lakes 40 000

Fossil fuel 5000

Vegetation 760

7.5

105 102

0.5

60

110

50

62

Carbonate rocks 75 000 000

0.5

Stores Pg Flows Pg yr-1

From FAOSTAT3.FAO.ORG

Agriculture

Changes of CO2 in atmosphere and plant (and soil) evolution

Not just CO2

mg d-1 CO2e

CO2 CH4 N2O

Wetland 801-1130 1934-3054 95-191

Riparian -629 -0.6 28

Net 1430-1758 1935-3055 66-162

Table 1. CO2 equivalent mean gas emissions

CH4 most significant gas in terms of GWP

No uptake

Adam Freer

Cultivation of organic soils

www.faostat3.org

Adapted from Johnston et al (2009) photo www.Rothamsted.ac.uk

Broadbalk continuous wheat experiment

Farmyard manure annually

Farmyard manure annually since 1885

NPK

1820 1840 1850 1880 1900 1920 1940 1960 1980 2000 2020

100 80 60 40 20 0

Organic carbon in soil (t C ha-1)

unmanured

• Photos of soils

A variety of soils Soils play a significant role in regulating water and climate We depend on them and so does the rest of biota Let’s work together to better understand, protect and enhance soil functioning