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 j.rickson@cranfield.ac.uk

+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?