Improving soil structure and reducing soil degradation - Managing... · Non-SSD NSLT MPP WT) SSD...
Transcript of Improving soil structure and reducing soil degradation - Managing... · Non-SSD NSLT MPP WT) SSD...
Managing soils for profit and restoration
Improving soil structure and
reducing soil degradation
Professor R Jane Rickson
Chair in Soil Erosion and Conservation
Cranfield Soil and AgriFood Institute
January 19th 2016
Outline of the presentation
1. What makes a healthy soil?
2. Soil degradation: cause or effect of ‘poor’
soil health?
3. The importance of soil management for
healthy soils
4. Take home messages
1. What makes a healthy soil?
• Traditional view: soil as inert material
• Modern view – soil as a living organism – “Physiology” = scientific study of normal function in living
systems
– Soil physiology = interactive, dynamic, process-oriented
study of soils and their ‘functions’
• Soil functions “Soil sustains, regulates and controls biotic and abiotic
processes [e.g. crop production, water infiltation] through its
interactions with the biosphere, hydrosphere, atmosphere
and lithosphere” (Yaalon, 2000)
• Soils deliver “ecosystem goods and services” – e.g. crop production, water regulation, carbon storage
– linked to human health and wellbeing, and individual and
national economic status (Daily, 1987)
1. What makes a healthy soil?
1. Soil Quality
“the capacity of soil to function, within natural or managed ecosystem
boundaries, to sustain plant or animal productivity, maintain or enhance
water quality, and support health and human habitation”
Karlen et al., 1997
2. Soil Health
“the soil’s fitness to support crop growth without becoming degraded or
otherwise harming the environment ”
Karlen et al., 1997
1. What makes a healthy soil?
Soil quality and soil health are related to soil
properties:
– Physical (texture, depth, structure, porosity,
density, water holding capacity, infiltration
rate, stability of individual aggregates and
soil mass)
– Biological (flora and fauna e.g. seed bank,
micro and macro organisms)
– Chemical (nutrients, carbon, pH)
…and interactions between them: soil as a
complex ‘system’
How can we tell we have a healthy soil?
Concept of Soil Quality Indicators (SQIs)
ORGANIC MATTER
NUTRIENTS STRUCTURE
WATER/AIR BIOTA
Soil Health: “The pivotal 5” (after Professor Karl Ritz, pers.comm)
6
Selected indicator Rationale for selection
Physical
SQIs
Topsoil-depth Estimate rooting volume for crop production and erosion
Aggregation Soil structure, erosion resistance, crop emergence and early indicator of
soil management effect
Texture Retention and transport of water and chemicals, modeling use
Bulk density Plant root penetration, porosity, adjust analyses to volumetric basis
Infiltration Runoff, leaching and erosion potential
Biological
SQIs
Soil respiration Biological activity, process modeling; estimate of biomass activity, early
warning of management effect on organic matter
Chemical
SQIs
pH Nutrient availability, pesticide absorption and mobility, process models
Organic matter Defines soil fertility and soil structure, pesticide and water retention, and
use in process models
Forms of N Availability to crops, leaching potential, mineralization/immobilization
rates, process modeling
Extractable N, P and K Capacity to support plant growth, environmental quality indicator
Suspected pollutants Plant quality, and human and animal health
Electrical conductivity Defines crop growth, soil structure, water infiltration; presently lacking in
most process models
Example of key soil quality indicators (Minimum data set – MDS)
after Arshad and Martin, 2002; Arshad and Coen, 1992; Doran and Parkin, 1994; Gregorich et al., 1994; Larson and Pierce, 1994;
Carter et al., 1997; Karlen et al., 1997; Martin et al., 1998
Soil Quality Indicators
e.g. Visual Soil Assessment / Evaluation – Composite SQI that reflects physical, biological and chemical properties
– Substitute ‘space for time’ analysis of soil conditions
Visual soil
assessment /
evaluation
http://www.landcarere
search.co.nz/publicati
ons/books/visual-soil-
assessment-field-
guide
2. Soil degradation:
cause or effect of ‘poor’ soil health?
As identified in the EU Thematic Strategy for Soil Protection (2006)
• Estimated 12 million hectares of
agricultural land are lost to soil
degradation every year.
ORGANIC MATTER
NUTRIENTS STRUCTURE
WATER/AIR BIOTA
Soil erosion in the UK:
cause or effect of poor soil health?
2. Soil degradation: cause or effect of ‘poor’ soil health?
Example: Soil erosion in England & Wales
Wind erosion Tillage
erosion
Co-extraction with root
crops and farm machinery Water
Typical erosion rate
range (t ha-1 year-1) 0.1 – 2.0 0.1 – 10.0 0.1 – 5.0 0.1 – 15.0
Land use affected
Arable,
upland, some
pasture
Arable Arable
Arable,
pasture,
upland
Exported off field Yes No Yes Yes
Comparison of the magnitude of soil loss for different erosion processes (Owens
et al., 2006). N.B. Rate of soil formation ≈ 1 t ha-1 year-1 (Verheijen et al., 2009)
2. Soil degradation:
cause or effect of ‘poor’ soil health?
• Irreversible loss of a natural resource / asset? e.g. loss of soil depth due to erosion
• Yield decline (quantity, quality and reliability; e.g. 20 million tonnes of grain per annum; UNCCD, 2011)
• 94 - 97% of our food originates in the terrestrial environment
• Costs (e.g. nutrient replacement)
• True impacts on food production often masked by unsustainable inputs (e.g. irrigation, chemical fertilisers)
2. Soil degradation:
cause or effect of ‘poor’ soil health?
• True impacts on food production often masked by unsustainable inputs (e.g. irrigation,
chemical fertilisers)
£ million per year (2010) Ecosystem service
Total
Provision-ing
Regulating Cultural
Agricultural production
Flooding Water quality
Green-house gas emissions
Other Central
estimate
Erosion 30 - 50 46 - 80 55 - 62 8 - 10 ? ? 165 13%
Compaction 180 - 220 120 - 200 60 - 80 30 - 40 ? ? 481 39%
Loss of organic matter 2 ? ? 360 - 700 ? ? 558 45%
Diffuse contamination ? ? ? ? 25* ? 25 2%
Loss of soil biota ? ? ? ? ? ? ? ?
Soil sealing ? ? ? ? ? ? ? ?
TOTAL 212 - 270 166 - 280 115 - 142 398 - 750 25 ? 1,229
% 20% 19% 11% 49% 2% 100
*cost of regulation to protect soils from contamination
? Estimates not available at national scale
3. The importance of soil
management for healthy soils
A. Enhance productivity (quantity, quality and reliability of marketable yield)
– Provide physical support to canopy and root development
– Improve uptake of water and nutrients by roots
– Reduce pests / diseases / weeds
B. Control soil degradation
– Erosion; diffuse pollution; compaction; losses of C, organic matter and habitats; salinisation; acidification
C. Concept of “sustainable intensification”
– Producing more (quantity/ quality/ reliability of marketable yield) with less environmental impact / damage
A + B = C
Aim: “To maintain a fertile seedbed and root zone, whilst retaining
maximum resistance to soil degradation”
ORGANIC MATTER
BIOTA
NUTRIENTS STRUCTURE
WATER BIOTA
Soil health: the pivotal 5
Soil erosion, Bedfordshire
Soil management practices for
healthy soils: examples
1. Soil cultivation and tillage – Maintain soil structure
– Prepare a suitable growing medium for a crop (germination, emergence and development)
– Maintain organic matter and soil biology
– Bury/incorporate surface residues/FYM
– Remove local or general soil compaction problems (promote drainage)
– Provide adequate soil strength to support surface traffic
2. Crop agronomy
3. Increasing soil organic matter content
+ 14 minutes rainfall
Soil management practices for
healthy soils
a) Conventional v conservation tillage
– reduced tillage, minimum till, strip
tillage, zero till, etc.
– The main reasons to use min-till are:
To reduce energy consumption
To reduce labour, fuel and
machinery costs
High work rates
To conserve moisture
To retain plant cover to minimize
erosion
Minimise loss of organic matter
Keep soil structure / less
compaction
+ 14 minutes rainfall
Courtesy of Professor Karl Ritz
Soil management practices for
healthy soils
a) Conventional v conservation tillage
‘Challenges’ of min-till
• Min-till needs dry ground conditions for
sowing in order to avoid compaction
and smearing in the final seed bed.
• “One of the best tools in your tool box
for min-till is patience”
• Wait until conditions are excellent for
sowing. Avoid sowing in a compacted
or smeared seed bed.
• Residue management
– Slugs
– Machinery
• Weeds and costs of control (economic
and environmental)
+ 14 minutes rainfall
Courtesy of Professor Karl Ritz
Soil management practices for
healthy soils
1. Soil cultivation and tillage
b) Timeliness of operations soil moisture content when trafficking – erosion and compaction risks?
c) Depth of operations plough pan formation?
effects on biota?
doubling the working depth, approx. quadruples the drawbar pull force and fuel requirement
d) Direction of operations (up/down on steep, marginal land)
A case study:
Optimising soil disturbance and use of mulches for
erosion and runoff control
Dr. Joanne Niziolomski
Shallow soil disturbance (175 mm), both with and without straw mulch (6 t ha-1).
Winged tine Narrow with two shallow
leading tines Modified para-plough
Field trial treatments
– Modified para-plough with straw most reduced soil loss
– Little significant difference was observed between SSD (different tines) and Non-SSD
– Straw mulch decreased total soil loss as compared with no mulch
Soil disturbance field trial results:
Total soil loss (kg)
0
1
2
3
4
Non-SSD NSLT MPP WT
To
tal so
il lo
ss (
kg
)
SSD type
No shallow Narrow tine shallow Modified Winged tine soil disturbance leading tine para-plough
(Niziolomski, 2015)
Soil management practices for
healthy soils
2. Use of crop agronomy for better soil management
– Rotations
– Cover and companion cropping
– Break crops (deep rooting species)
– Nutrient replenishment (e.g. N fixing legumes)
– Grass waterways (erosion and runoff control)
N.B. Eligible for Basic Farm Payment under CAP reform and ‘greening’
rules
Crop
Root
Type
Root traits expected to
improve soil structure
Wheat D Fibrous vigorous deep
roots
Rye D Deep fibrous roots
Oats D Aggressive deep roots
Italian
ryegrass F
Fibrous root system
Lucerne E Deep and aggressive
rooting
Phacelia F Prolific root system but
more confined to surface
Fodder
radish T
Tap root, long and
extensive root hairs on
laterals
Chicory T Tap root
Sweet
clover E
Vigorous and extensive
multi-order lateral
branching,
Field bean E Large, strong roots
Lupin E Tap root
(Ritz, 2014)
Root morphology of cover crops
T D F E T D F E
Radish Mustard
Turnip Rape
Cranfield University PhD study (Agnese Mancini):
Cover crops for soil erosion and runoff control in forage maize
Case study:
Use of grassed waterways for sediment
control
Case study:
Use of grassed waterways for sediment
control
Soil management practices for
healthy soils
3. Increasing soil organic matter content
– Green manures (cover cropping)
– Composts
– Mulches
– Sewage sludge
– Digestate from AD plants
Increase organic matter content, carbon, soil biota
Improve soils structure and resilience
Effects will be specific to materials used and sites
(weather, soil type, etc)
http://www.biogen.co.uk/The-Biogen-Difference/The-
Closed-Loop
Case study:
Application of organic waste to restore soil
health and productivity of a degraded soil Benedict Unagwu
Increase crop
yield?
Poultry
manure
Mushroom
compost
PAS
compost
(green
waste)
Anaerobic
digestate
Improve Soil Quality
Indicators (SQIs)?
Key: C = Control; PM = Poultry manure; PAS = PAS 100:2005 Quality Protocol compliant compost; SW = Anaerobic
digestate solid waste; MC = Mushroom compost; 1 = 10 t ha; 2 = 30 t/ha. F = with fertiliser; NF = without fertiliser
Results: Post-incubation soil
analysis (OMC and Total N)
Mean
Mean±SE
CF
CN
F
PM
1F
PM
1N
F
PM
2F
PM
2N
F
PA
S1
F
PA
S1
NF
PA
S2
F
PA
S2
NF
SW
1F
SW
1N
F
SW
2F
SW
2N
F
MC
1F
MC
1N
F
MC
2F
MC
2N
F
Treatments
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
OM
(%
)
F(17,62) = 16.0899, p = 0.0000
Mean
Mean±SE
CF
CN
F
PM
1F
PM
1N
F
PM
2F
PM
2N
F
PA
S1
F
PA
S1
NF
PA
S2
F
PA
S2
NF
SW
1F
SW
1N
F
SW
2F
SW
2N
F
MC
1F
MC
1N
F
MC
2F
MC
2N
F
Treatments
0
40
80
120
160
To
tal o
xid
es o
f N
itro
ge
n (
mg
kg
-1)
F(17,62) = 4.3294, p = 0.00001
Amendment effects on maize height and biomass
28
control
10 t ha-1 PM
At 3 weeks after planting
10 t ha-1 MC
At tasseling (9 weeks after planting)
4. Take home messages
• Healthy soils deliver multiple ecosystem goods and
services, but can be irreversibly degraded
• Soil management can improve soil productivity and
control degradation processes
• Cost effectiveness of practices will be site specific
and must fit into current farming practices
– socio-economic context
– infrastructure / machinery
– farmer psychology / behaviour
• Ultimate goal is economically, socially and
environmentally acceptable food production
= “sustainable intensification”
ORGANIC MATTER
BIOTA
NUTRIENTS STRUCTURE
WATER BIOTA
In conclusion…..
“The challenge for global agriculture is to grow more food, on
not much more land, using less water, fertiliser and pesticides
than we have historically done.”
Sir John Beddington
former UK Government Chief Scientific Adviser.
‘The answer is in the soil……’
Thank you for your attention
Professor Jane Rickson [email protected]
+44 1234 750111 ext. 2705
What kind of measures are used? 0 10 20 30 40 50 60 70 80 90
Riparian buffer strip / zone
Establish in-field grass buffer strips
Establish edge-of-field buffer strips
Convert arable land to extensive grassland
Mulching / crop residue management
Cover cropping
Strip cropping
Adopt minimal cultivation systems
Remove compaction in affected fields
Cultivate and drill across the slope
Leave autumn seedbeds rough
Tramline management
Maintain and enhance soil organic matter levels
Allow field drainage systems to deteriorate
Reduce grazing intensity
Constructed waterways
Infiltration / detention / retention basins, ponds and…
Contour bund
Mean % effectiveness of erosion control measures (after Rickson, 2014 Sci. Total Env.)
What sort of measures are used to control soil erosion?