Upload
others
View
14
Download
0
Embed Size (px)
Citation preview
Managing soil biology
Stephen Briggs MSc, BSc, IOTA, Nuffield Scholar
• Dirt or Soil – What's the difference ?
• Soil life / soil biology
• Feeding soil biology
• Soil analysis
• Practical steps for good soil biological management
Managing soil biology
• Dirt or Soil – What's the difference ?
• Soil life / soil biology
• Feeding soil biology
• Soil analysis
• Practical steps for good soil biological management
Managing soil biology
Natural SuccessionNatural Succession
“It takes more than 500 years to form an inch of topsoil.” “It takes more than 500 years to form an inch of topsoil.”
Structure and ‘Structure and ‘habitathabitat’ for soil life is important ’ for soil life is important
• Dirt or Soil – What's the difference ?
• Soil life / soil biology – What is it – Different types – The soil food web and how it works – The benefits of the soil food web – What is needed for good soil biological life
• Feeding soil biology
• Soil analysis
• Practical steps for good soil biological management
Managing soil biology
Plant roots move to nutrientsPlant roots move to nutrients Nutrients have to be ‘Nutrients have to be ‘processedprocessed’ to be ’ to be made plant available (by soil microbes)made plant available (by soil microbes)
Nutrients need processing Nutrients need processing into available forms into available forms
for plant uptake for plant uptake
(by soil microbes)(by soil microbes)
FertilisersFertilisers
But what about the impact of pesticides and But what about the impact of pesticides and fertilisers on the soil microbial food chain ?fertilisers on the soil microbial food chain ?
Above ground
Mycorhizae
• Myco = fungus rhiaze = root
• More than 90% of plants have a mycorrizal symbiont
• Ectomycorrhizae (external)
• Endomycorrhizae (internal)
Mycorrizal Fungi hair like filaments (hyphae) bind soil particles together, helping create friable structure soil
•Foliar applications of non systemic fungicides have less effect even though some reach the soil •Soil applied non systemic fungicides can inhibit VAM – esp when roots small at low colonization rates •Greater impact on ‘ecto’ (outside) VAM than ‘endo’ (internal) VAM •Systemic fungicides generally inhibit VAM •Fungicidal seed treatments = varied impacts •Choose Fungicide carefully !
• Dirt or Soil – What's the difference ?
• Soil life / soil biology
• Feeding soil biology – What kind of feed – When – how
• Soil analysis
• Practical steps for good soil biological management
Managing soil biology
Material C: N ratio
Soil microorganisms 7
Soil organic matter (SOM) 10 – 12
Clover 13
Compost 15
Grazing Rye 36
Maize stems 60
Wheat straw 80
Fresh sawdust 400
Soil Organic Matter
Decline in mean soil organic carbon concentration (% g Decline in mean soil organic carbon concentration (% g gg--11) for UK loam soils (1.3 ) for UK loam soils (1.3 MhaMha). ).
2.18
2.2
2.22
2.24
2.26
1930 1940 1950 1960 1970 1980 1990 2000 2010 2020
Year
SO
C (
% g
g-1
)
MC1
MC7
MC1 = from permanent grassland MC7 = cultivation Dotted lines beyond 2000 represent projections assuming no further management changes (Source : Canfield University Defra Project SP0553 2003)
2.24 2.24 –– 2.00%2.00%
= 11% loss= 11% loss
English soil SOC concentrations
= 1.3% (g g-1) Red pixels = 2.3% (g g-1) Green pixels = permanent grassland & native vegetation
Arable sites tending to 1.3% Carbon
Arable sites tending to 2.3% Carbon
Pemanent grassland
Other landuses (not arable or permanent grass)
Arable sites unable to classify
(Source : Canfield University 2013)
In natures termsIn natures terms
“Cultivation is a catastrophic event !”“Cultivation is a catastrophic event !”
• Dirt or Soil – What's the difference ?
• Soil life / soil biology
• Feeding soil biology
• Soil analysis – What standard analysis is tells you (and not) & what its for – Other information – Approaches for soil biological management
• Practical steps for good soil biological management
Managing soil biology
• Dirt or Soil – What's the difference ?
• Soil life / soil biology
• Feeding soil biology
• Soil analysis
• Practical steps for good soil biological management
Managing soil biology
Suppression of plant pathogens
Improved soil structure and water retention
Greater diversity of soil organisms
Supply of plant nutrients
Some benefits of compost
Typical nutrient content Green waste compost
Material DM
(%)
Total
(kg/t fresh wt)
Readily available
(% of total)
N P2O5 K2O N P K
FYM
25 6.0 3.5 8.0 25 60 60
Cattle slurry 6 3.0 1.2 3.5 30-50 50 90
Sewage
sludge
25 7.5 8.7 0.8 15 50 100
Green waste
compost
66 7.3 3.0 5.5 <10 15 50
Compost use
• 1997 – 2000 study
• Green waste compost
• Animal manures (FYM, cattle slurry, poultry bedding)
• Spread at various rates, both annually and as a one off application
Effects on yields
Linseed
Wheat
Barley
OSR
Wheat
0
2
4
6
8
10
12
1996 1997 1998 1999 2000
Yie
ld
(t/
ha)
Standard fertiliser applications
Slightly reduced fertiliser applications + low rate compost
No fertiliser application + high rate compost
Much reduced fertiliser application + high rate compost
• Green waste compost used on its own or in combination with artificial fertilisers
• A series of combinable crops were grown
Green waste compost: • Is a good source of P and K
• Contains nitrogen in a very unavailable form
which is unlikely to lead to nitrate leaching
• May improve soil structural and soil biological life
• Is particularly appropriate for use in farming systems where the crops are of high value
Consider Above & Below Ground
Root Spread and depth ?
Winter wheat Spring Wheat Peas Sugar Beet Pots W clover Lucerne
Forage Legumes
White clover Trifolium repens
Red clover Trifolium pratense
Crimson clover Trifolium incarnatum
Subterranean clover Trifolium subteranneum
Alsike clover Trifolium hybridum
Persian clover Trifolium resupinatum
Egyptian clover Trifolium alexandrinum
Lucerne/alfalfa Medicago sativa
Winter/common vetch Vicia sativa
Summer/goar vetch Vicia lathyroides
Hairy vetch Vicia hirsuta/villosa
Kidney vetch Anthyllis spp
Sanfoin Onobrychis viciifolia
Large birdsfoot trefoil Lotus pedunculatus
Birdsfoot trefoil Lotus corniculatus
Trefoil/black medick Medicago lupulina
White lupin Lupinus alba
Yellow lupin Lupinus luteus
Blue lupin Lupinus angustifolius
Grain legumes
Field peas Pisum sativum
Fodder (grey) pea Pisum arvense
Field bean Vicia Fabia
French /pinto bean Phaseolus vulgaris
Soya bean Glycine max
Lentil Lens culinaris
Other legumes
Galega, Goats rue Galega orientalis
Chickling vetch, sweet pea Lathyrus spp.
White Sweet clover Melilotus alba
Chickpea Cicer arietinum
Black bean Castanospernum australe
0 100 200 300 400 500 600
kg N/ha/year
Red clover (silage)
Lucerne (silage)
Field bean (grain crop)
Forage peas
White clover/grass (grazed)
Lupin (grain crop)
Vetch (cut & mulched)
Soya (grain crop)
White clover/grass (silage)
Provisional ranges for quantities of N fixed and remaining after harvest
N fixed
N after harvest
(including roots)
Source : OF0316 – Adas, Abacus Organic, Duchy College, IGER
Conclusions • Soil biology is key to soil health
• Nutrients require microbial processing
• Soil microbes need good stable habitat
• Feed soil microbial populations
• Green manures, catch crops, cover crops
• Consider quick growing spp. - between
harvest and planting next crop
• Under-sow in previous cash crop
• Environmental management / X compliance
• Cultivations – catastrophic for soil biology
• Cultivations - Inversion > non-inversion
• Reduce biological disruption = reduce nutrient loss
• Use all fertilisers carefully – salts damage soil life
• Fungicides & insecticides damage soil life
• Index soil analysis – replacement of ferts only
• Consider soil biological monitoring
“A GOOD FARMER IS“A GOOD FARMER IS NOTHING MORE NOTHING MORE NOR LESS THAN A NOR LESS THAN A
HANDYMAN WITH A HANDYMAN WITH A SENCE OF HUMUS”SENCE OF HUMUS”
(E.B WHITE)
Become subterranean livestock farmersBecome subterranean livestock farmers
Stephen Briggs MSc, BSc, IOTA, Nuffield Scholar
Objectives:
• You’ll appreciate the work that soil life does, and what it needs to function
• You’ll meet some soil organisms up close and think about how they live
• You’ll explore how land management affects soil life and soil function
Soil’s Work
• “the biological engine of the earth”
• Engines need fuel…
Illustrations: Matthew Shepherd
What does the soil do?
• Carbon in plant organic matter is the carbon source…
Illustrations: Matthew Shepherd
Bacteria
Bacteria
Myxobacteria photo: Michiel Vos doi:10.1371/journal.pbio.0030398
Photo: Julia Plotnikov
Firmicutes Photo: Wikimedia commons
Photo: GrahamColm at en.wikipedia
Photo: http://genomics.energy.gov
Photo: Matthew Shepherd Photo: Matthew Shepherd
Photo: MS Turmel, University of Manitoba,
Plant Science Department
Fungi (incl.
mycorrhiza)
Decomposers Photo: Kirsten Harvey
Photo: Michel Vuijlsteke Photo: Sonia Martinez
Photo: Andy Murray
Photo: Matthew Shepherd
Photo: Matthew Shepherd
Photo: Matthew Shepherd
Photo: B Kimmel at nl.wikipedia
Predators
Photo: Matthew Shepherd
Photo: Matthew Shepherd Photo: Palica, Wikipedia
Photo: Matthew Shepherd
Photo: James K. Lindsey
Earthworms and
Potworms
Photo: Michael Linnenbach
Photo: Natural History Museum, London
Photo: Mihai Duguleana
What does soil life need to work?
• Energy source – plant roots, litter, exudates and partnerships
• Space to live – soil pores and litter
• Moisture
• Lack of disturbance (at their level and timescale)
• Chemical stability – pH, solutes etc.
• No dangerous toxins
• Comfortable temperatures
Activity Sessions – 12 mins each
• Session 1: Assessing soil biological health – looking at soil blocks – what they can and can’t tell us.
• Session 2: Meet the soil Beasties – quick whiz around the microscopes – factsheets.
• Session 3: Problems, solutions and impacts – card game
• PLEASE LEAVE EACH ACTIVITY AS YOU FIND IT!
What is “good” soil structure?
• A soil that sustains healthy and high yielding crops as well as fulfilling its role of buffering chemicals, water and air to maintain a healthy environment
– the economics of creating and maintaining this have to work as well!
What are the physics of a “good soil structure”?
• A heterogeneus (diverse) mix of solids, air and water with a continuous network of pores that allow free movement of air, water and roots
What can we influence or manage?
With acknowledgement to R.C. Palmer, Independent Soil Assessment Specialist [email protected]
The volume of soil that we can influence
How do we improve soil structure?
• Increase organic matter levels
– Maximise level and duration of green or other cover
– Avoid stresses on the soil:
• compaction
• tillage
• starving wildlife
• bare fallows – at any time
• raindrop impact
The importance of SOM!
• Without soil organic matter (SOM), soils have no structure or life
– SOM is the primary food source for all soil living animals and micro-organisms
– SOM initiates aggregation of soil particles and thus porosity
– Animals and roots create further porosity
The dynamics of SOM
• Plants add SOM
• Soil micro-organisms break it down – Addition or loss of SOM is the balance of these
two processes
• “Inappropriate” tillage increases loss by exposing more of the soil to microbes
+ -
+ -
Increasing SOM
• There is no controversy about increasing SOM
– it is beneficial on practically all levels
Addition of SOM
• Cover crops
–with large vigorous roots
– as much growth and over as long a time period as possible
–must be compatible with cash crops
Effect of impervious layers on soil water content
• A practical demonstration of drainage constraints
Compaction makes soils stronger
First video, random traffic no-till for 3 years
Second video, zero traffic no-till for 3 years
Compaction makes soil management more difficult and costly
• Energy to loosen. Energy to re-compact
• Loss of moisture
• Uneven germination and growth
– Timeliness effects on subsequent chemical applications
Addressing the principles Choosing and using tyres correctly
• Learn the principles
– manufacturer’s literature and training workshops
• tyre data book or pdf
– lowest inflation pressure for load and speed
Tyres – what’s the correct inflation pressure?
• Example from tyre data book
– 18.4R34 tyre
Tyre rolling radius, mm
Max speed, km/h
Load, kg at:
Pressure 0.8 bar 1.0 bar 1.2 bar
744 10 2745 3010 3275
744 30 2160 2370 2580
744 40 2015 2210 2410
Choosing the right tyres
Axiobib - 20% more load at same pressureAxiobib - 20% more load at same pressure
Xeobib – 40% more load at same pressureXeobib – 40% more load at same pressure
Tracks
• Lay down area in length rather than width
– but pressure not even under this length
Ground pressure time history
0.0
0.5
1.0
1.5
2.0
2.5
3.0
0 1 2 3 4 5 6 7 8 9 10
Time, secs
Record
ed p
ressure
, bar
128
107
177
271
421
Run No. 4\3\1\009
combine rear wheels
combine track
Accepted thinking: most stress under tracks is
dissipated in the topsoil
Tracks
• Advantages
– Less area tracked on each pass
– More efficient pulling power
• 4% compared with 10% slip
– Less rutting
• Disadvantages
– Heavier than wheels
– More expensive than wheels
– Can do more damage to crops on turning
Good
Not so good
265 kW tracked tractor – 25% premium compared with equivalent wheeled tractor of 425 kW
Setting up machinery combinations properly
• Mounted cultivators
– correct ballasting
– 3-point hitch geometry
• top link position should ensure weight transfer onto rear wheels
• Trailed cultivators
– correct ballasting
– particularly important with single tracks
Fuel savings
• Adaptive driving 10-20%
• Appropriate settings 5-10%
• Engine maintenance 5-10%
• Diesel quality 3-5%
• Appropriate ballast 5-8%
• Correct tyre pressures 5%
Keep an eye on weight
• Take time to remove excess weight
Not always easy or appropriate
and can remove too much!
0.00
0.20
0.40
0.60
0.80
1.00
1.20
1.40
1.60
1.80
2.00
Timeline from the 1930s to the present day
Pre
dic
ted
pre
ssu
re a
t 0
.5 m
de
pth
, bar
850 kg Horse
11.2-28
12.4-36
16.9-34
18.4-38
16.9 R 34
710/70 R 38
800/65R32
1050/50R32
The effects of increasing weight
2.5 t vehicle
21 t vehicle It’s load that does damage at depth
And we apply weight to a big area
Traditional: Average: 85% tracked
Kroulik et al,
2011
grain carting
straw carting
straw baling
Wheat Czech Republic
• any system that confines all tracks to least possible area of permanent traffic lanes
– CT is NOT prescriptive about tillage
– CT is NOT just about keeping tramlines in the same place
– Commitment to continual improvement
Another approach
Controlled Traffic Farming - CTF
CTF has a lot of benefits
• Yield improvements
• Improved fertilizer use efficiency
• Lower and less intensive tillage
• Large fuel savings
• Lower operating and capital costs
• Improved soil health
– 4 x better water infiltration & conductivity
– lower greenhouse gas emissions
– more soil-living animals
but equally CTF has some drawbacks
• It needs careful planning and attention to detail
– matching track gauges
– matching implement widths
• It requires investment in auto-steer
• It introduces an element of inflexibility
• Probably needs a change in agronomy
– less and shallower tillage
– different soil structure
Trailer
Grain auger
Cereal harvesting
Cultivator/drill
Chemical application
Take home messages
• Improving soil structure is a long-term commitment involving
– lowering soil stresses
• tillage and traffic
• choosing and using tyres correctly
– increasing organic matter levels
• less tillage
• cover cropping
• retaining residues
• adding composts and manures
Take home messages
• Improving soil structure
– Controlling traffic can be part of the solution
– It can also:
• make farming simpler
• lower inputs
• raise yields
• reduce negative environmental impacts