soil regulating functions · 2015-06-11 · add figure 5.12 • clay soil holds more water than...
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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)
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
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