Stop Treating Soil Like Dirt! Soil Workshop Soil is living! There - - PowerPoint PPT Presentation

Stop Treating Soil Like Dirt! Soil Workshop

Soil is amazing!!

• Soil is living! There are more microorganisms

in a teaspoon of healthy soil than there are people on earth.

Soil is amazing!!

• Soil holds over twice the carbon than what is presently in all the world’s above

ground vegetation and in the air!

Soil is amazing!!

• Soil microbiomes may also contain antidepressants!

Soil on your Orchard

• Physical support for plants and posts
• Supplies water and nutrients to plant

roots

• Regulates temperature of the roots
• Provides drainage of excess rainfall

Healthy Soil is Important for Sustainability

• Healthy soil supports:
• Nutrient retention
• Water efficiency
• Supports production
• Prevents sediment loss
• Builds Resiliency

Stop Treating Soil Like Dirt Zespri Soil Workshop 2019 Part 1: Soil Basics

Dr Charles ‘Merf’ Merfield MRSNZ charles@merfield.com

The Future Farming Centre

Permanent Agriculture and Horticulture Science and Extension www.bhu.org.nz/future-farming-centre

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A presentation in four parts

Soil basics Soil chemistry Nitrogen – the joker Soil health – putting it all together

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My Background

Commercial Horticulture Diploma, late 1980s, UK Managed organic vegetable farms in UK and NZ for 7 years supplying farm shops and restaurant trade - grown nearly every vegetable there is M.Sc. and PhD at Lincoln Uni Experience in UK, Ireland, EU, USA, Uruguay & Oz Founding head of the BHU Future Farming Centre

The Future Farming Centre

Part of the BHU Organics Trust - based at Lincoln Uni Not for profit - charitable trust Old-school ag and hort research coupled to extension / tech transfer and consulting A quarterly free newsletter - FFC Bulletin Just handing out knowledge:

– No preaching, no politics – Separating snake-oil from science

www.bhu.org.nz/future-farming-centre

Upon handful of soil our survival

• depends. Husband it and it will grow
• ur food, our fuel, and our shelter and

will surround us with beauty. Abuse it and the soil will collapse and die, taking humanity with it. — Atharava Veda, the Sanskrit Scripture, 1500 BC.

‘What greater stupidity can be imagined that that of calling jewels, silver and gold, “precious”, and earth and stone “base”? People who do this ought to remember that if there were as great a scarcity of soil as of jewels or precious metals there would not be a prince who would not spend a bushel of diamonds and rubies and a cartload of gold just to have enough earth to plant a jasmine in a little pot,

• r to sow an orange seed and watch it sprout, grow

and produces its handsome leaves, its fragrant flowers and fine fruit.’

Dialogue on the Two Chief World Systems Ptolemaic and Copernican, Galileo.

“A nation that destroys its soil, destroys itself.”

President Franklin Roosevelt

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So what is soil?

Ground up rock is regolith – not soil. Soil is biologically active Soil is a living ecosystem It could be considered an organism in its own right

Soil is alive!

The Living Soil

Components of a healthy soil

Physical

– Structure – Bulk density – Aggregate stability – Aeration – Infiltration – Water holding capacity

Chemical

– Biologically available nutrients – pH – Minimising losses

Biological / ecological

– Organic matter

• Living
• Dead

– Biodiversity

Physical health varies with soil texture

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Healthy soil structure

Healthily structure should be like a sponge - a lot of holes

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Bulk density

Low density = healthy High density / compacted = unhealthy Compact soil due to

– Machinery, animal and human compaction – Cultivation / tillage – Lack of living plants - ‘ground cover’ / living mulch

Permanent beds for vegetables farmer guidelines 2013 www.landwise.org.nz

Aggregate stability

https://www.farmersjournal.ie/itlus-tour-improved-soils-provide-more-and-cheaper-output-217972

Aeration and infiltration

Good structure – back to being like a sponge

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Water holding capacity

Soil texture big effect – but can’t be changed Soil organic matter – key manageable driver 1% of organic matter can hold 250 cubic meters of water /ha which equates to 25 mm / inch of rain

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Chemical soil health

Optimum levels of biologically (plant) available nutrients Optimum pH Minimizing nutrient losses to the environment, mainly N (nitrate) and P

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Biological / ecological soil health

‘Good’ levels of soil organic matter (SOM)

– Living – Dead

• Short (days), medium (years, decades), long term (centuries, millennia)

residency.

High level of biodiversity

– Microbes (micro fauna), e.g. bacteria, fungi, are the most important – Bigger stuff (macro fauna) e.g. worms, nematodes

The soil food web

(de Ruiter et al. 1993, J Appl Ecol 30, 95-106)

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Stop Treating Soil Like Dirt Zespri Soil Workshop 2019 Part 2: Soil Chemistry

Dr Charles ‘Merf’ Merfield MRSNZ charles@merfield.com

The Future Farming Centre

Permanent Agriculture and Horticulture Science and Extension www.bhu.org.nz/future-farming-centre

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Soil chemistry

Soil science in agriculture has mostly been soil chemistry / fertiliser science Main focus for the past 70 odd years The focus is moving to a holistic perspective which includes soil biology But, that does not mean the chemistry is now unimportant – it is the foundation on which the temple of soil biology is built

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Understanding soil nutrient testing

The issue of soil tests may appear done and dusted There is still a fair bit of misunderstanding about them

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Chemical soil tests

A simulation, based on an approximation, informing an empirical estimate, wrapped up in a value judgment!

Apologies to Winston Churchill “Russia is a riddle wrapped in a mystery inside an enigma”

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Proportion of nutrients in plants

Element Percent Element Percent Carbon 45.0 Sulphur 0.100 Oxygen 45.0 Iron 0.010 Hydrogen 6.0 Chlorine 0.010 Nitrogen 1.5 Manganese 0.005 Potassium 1.0 Boron 0.002 Calcium 0.5 Zinc 0.002 Phosphorus 0.2 Copper 0.001 Magnesium 0.2 Molybdenum 0.00001

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A simulation

Chemical laboratory tests are trying to simulate the amount of soil nutrients available to plants – a biological process Test tube chemistry trying to simulate biology! NB, available not total nutrients

Available plant nutrients

Total soil P 900 – 1,800 kg/ha P

Primary mineral phosphates Soil parent material

Soil solution Approx 500 g/ha Sorbed P in clays, humus and aluminum and ferrous oxides Organic P:

• Soil biomass (living)
• Soil organic matter
• Soluble organic P

Forms of elements taken up by plants

Element Abbreviation Form absorbed Nitrogen N NH4

+ (ammonium) and NO3

• (nitrate)

Phosphorus P H2PO4

• and HPO4
• 2 (orthophosphate)

Potassium K K+ Sulphur S SO4

• 2(sulfate)

Calcium Ca Ca+2 Magnesium Mg Mg+2 Iron Fe Fe+2 (ferrous) and Fe+3 (ferric) Zinc Zn Zn+2 Manganese Mn Mn+2 Molybdenum Mo MoO4

• 2 (molybdate)

Copper Cu Cu+2 Boron B H3BO3 (boric acid) and H2BO3

• (borate)

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An approximation – Soil sampling

1 ha = 7,500 tonnes soil in the plough layer (30 cm) Typical soil sample is 200- 400 g of soil May be for >10 ha of land A soil sample represents 0.0000007% of the plough layer - approximately! Correct field sampling is the most critical part of a soil test to get right

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An empirical estimate - Yield curves

Yield curves are entirely derived from empirical data from field trials No theory, no math's, no models Just zillions of bits of data from yield response experiments in the field

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Yield curves - the full story

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Yield curves – how they work

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Too much of a good thing

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Yield curves to fert recommendations

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Yield curves to fert recommendations

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An empirical estimate

Yield curves / fertiliser recommendations are too often considered to be highly precise and accurate They are in fact very fuzzy

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Real yield curves are fuzzy

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Real yield curves are fuzzy

50 100 150 200 250 300 350 400 450

P availability index (PAI)

0.0 0.2 0.4 0.6 0.8 1.0

Observed Predicted 95 % CIs 95 % PIs

E = 0.34

P availability index (PAI) fits and uncertainties

Data from Vadas and White. 2010. TASABE 53: 1469-1476. Slide from: Model Parameter Uncertainty Analysis for an Annual Field-Scale P Loss Model. Carl H. Bolster, Peter A. Vadas, & Debbie Boykin USDA-ARS. LuWQ 2015

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Impact of biology on a yield curve

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Wrapped up in a value judgment

Yield maximisation is not a scientific objective It is a value judgement You cant design an experiment that shows you ought to increase yield Only an experiment to show you how to increase yield Maximising yield is a moral / ethical judgement therefore outside

• f science

Hume's guillotine

David Hume, Scottish philosopher and historian 1711-1776 The is–ought problem You cant logically get from what is to what

• ught (should) to be

That we can maximise yield does not mean we

• ught to, even have to

Could just as well aim for crop quality or any

• ther measure of plant performance

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Justus von Liebig

Invented the Liebig condenser, marmite and oxo! The founder of organic chemistry One of the greatest chemistry teachers of all time The father of agricultural chemistry / fertilizer industry Popularized Carl Sprengel’s the ‘law of the minimum’

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Law of the Minimum

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Soil tests as a guide not an oracle

Tests are a guide not God Long term trends using exactly the same lab and test are the real gold - make a chart Coupled with YOUR observations of plant reaction to applied nutrients - i.e., are test recommendations over or under YOU need to build your own experience of your vines needs

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FFC Bulletin article

www.bhu.org.nz/future-farming- centre/information/bulletin/2015-v1/fundamentals-of-soil- nutrient-management-soil-testing-and-fertiliser- recommendations

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Stop Treating Soil Like Dirt Zespri Soil Workshop 2019 Part 3: Nitrogen

Dr Charles ‘Merf’ Merfield MRSNZ charles@merfield.com

The Future Farming Centre

Permanent Agriculture and Horticulture Science and Extension www.bhu.org.nz/future-farming-centre

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Overview

Understanding why N is the joker of the pack of plant nutrients / chemical elements How N (mis)behaves - the N cycle Practical organic, N management techniques

– In situ N fixation – Importing N

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Nitrogen - the joker / wildcard

Nitrogen Nitrogen

To understand nitrogen you need to understand why it is different

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The three nutrient classes

C,O,H delivered free by the atmosphere

– CO2 and H2O ‘atmospheric nutrients’

P,Ca,K,Mg,S,Fe, etc only come from the soil / rocks of the planet

– The ‘lithospheric nutrients’

Nitrogen ‘is’ the atmosphere - 80% but plants can only absorb it from the soil

– atmospheric + lithospheric nutrient

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Nutrient cycles

Lithosphere (rocks) + pedosphere (soil) = Geosphere solid & liquid Atmosphere gas Hydrosphere solid & liquid

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Carbon cycle

CO2

Soil - major carbon reservoir - 3 x the atmosphere

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Geological sediment uplift 10 - 50,000,000 years + Rock weathering Thousands of years Atmosphere

Lithospheric nutrients

Cycles are the same for all lithospheric nutrients

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Nitrogen cycle

N2 Nr N2 Nr Nr N2

Geosphere - very small amounts of N

Nitrogen (spaghetti) cycle!

Atmospheric, un-reactive di-nitrogen (N2) gas Biological nitrogen fixation by bacteria, cyanobacteria and actinomycetes in symbiosis with higher plants especially the Fabaceae (legumes) Nitrites NO2

• Nitrates NO3
• Ammonia NH3

Ammonium NH4

+

Decomposers Aerobic and anaerobic fungi and bacteria Reactive nitrogen in soil organic matter Ammonification Nitrification by nitrifying bacteria Nitrifying bacteria Assimilation by plants Biological nitrogen fixation by free living bacteria and cyanobacteria in the soil Reactive nitrogen stored in living plants and animals Assimilation by plants Denitrification by soil dwelling bacteria

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Nitrogen is the flip side of carbon N+C+O+H = soil organic matter (SOM) N sorbed onto organic matter N is therefore both in and on organic matter N management flip side of SOM management

Practical orchard N management N C

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Importing or fixing N

N comes from - and returns to - the atmosphere To get N into the orchard it has to either be:

– Imported i.e. as fertiliser, compost, manure – Fixed in-situ, by legumes

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Importing N

Difficult under organic standards Only biological-organic forms are permitted The main N compound in living things is protein Protein is 6.25% N (Jones factor) i.e., max N content of bio-ferts without fortification

• r concentration is 6%

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Importing N

Need data (not guess) on:

– Total N content of material – How much of the total N is available per year

All bio-organic ferts contain a wide (all) range of the other nutrients

– Need to include all other nutrients in fert calculations to make sure they are not over applied – Other nutrients may be higher than N

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Importing N - compost

Is a very poor source of N - 1-2% total N Has much more P & K on a plant needs basis Using compost to supply N will result in excess P & K A good soil conditioner It is not soil ‘food’

A literature review on the availability of phosphate from compost in relation to the Nitrate Regulations SI 378 of 2006. 2009 Prasad A literature review on the availability of nitrogen from compost in relation to the nitrate regulations SI 378 of 2006. 2009 Prasad

Importing N - compost

Need both total N and C:N ratio % of total N mineralised after application

Wallace, P. (2006) Production of Guidelines for Using Compost in Crop Production- A Brief Literature Review

Compost C:N ratio Over 3 years In year 1 In year 2 In year 3 10 25.0 12.5 7.0 5.5 13 17.5 8.0 5.0 4.5 15 10.0 5.0 3.0 2.0 18 5.0 2.5 1.5 1.0 20 0.0 0.0 0.0 0.0

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Importing N - Vermicompost

Compost made by worms – quite different to hot compost Higher nutrient levels than hot compost – depends on feed stock N as nitrate more than ammonium Need nutrient analysis of each batch - varies Cost and supply – fewer vermicomposters than hot composters

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Importing N - manure

If you can find organic certified manure… Total N

– Sheep manure 2% – Cow manure 0.7% – Pig manure 1.0% – Chook manure

• Cage (banned)

1.4%

• Litter

2.4%

from Practical Soil Management, Ian Cornforth

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Importing N - Foliar sprays

Importing N into organic orchards, and getting into the plant via the soil, is slow If vines are N deficient then N needs to be got directly into the plant…. Foliar sprays

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Importing N - Foliar sprays

Not recommended as the main N supply route - due to cost (materials and application) There are foliar sprays and foliar sprays

– Some are based on good science – Some are not – Caveat emptor

Ask to see research results / strong evidence Get good independent advice

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Importing N – Wool and feathers?

Wool and feathers contain up to 12% N Is there potential to use them as an N source? Issues:

– Certification rules

• Uncertified has to be composted – N lost
• Certified products – supply issues?
• Would they be allowed to be used as fertiliser?

– Decompose slowly – resistant to decay – Other issues?

Research project?

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Importing N – biodigestate?

Anaerobic digestion / biodigestion Giant steel rumen Unlike composting no N lost Biodigestate high in mineral N (ammonium) Grow high N feedstock – certified clover pasture Convert to biodigestate + methane – energy

???

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Making your own: Fixing N

Importing N in organic ag is difficult and expensive Fixing N in-situ is the dominant route A few key concepts underpin the process

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Biologic zero

The absolute zero of soil biology 5 - 10°C, average ~ 8°C Below this soil organisms, including diazotrophs (N fixing ‘bacteria’) are inactive → Little N fixation during winter → Most N fixation occurs during summer

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Serving up N and biologic zero

N in soil is in the form of organic matter To become available to plants it has to be mineralised into ammonium This is done by fungi and bacteria The release of soil N is therefore determined by microbial activity Which is determined by soil temperature

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Serving up N and biologic zero

If temps are close or below to biologic zero

– Zero N release

If other soil conditions suppress microbial activity, e.g., too dry, to hot

– Zero N release

Spring is the time when organic systems struggle for nitrogen - crops start growing and need N, soil microbes are still in bed

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Loosing N

The main form of Nr loss in healthy soils is leaching Mainly as nitrate NO₃− There has to be soil drainage Soil has to be above biologic zero so SOM can be mineralised to nitrate Spring and mainly autumn are the main loss periods

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Green manures and catch crops

Cover crops is the overarching term

– Green manures to fix N. – Catch crops to hold N

Basic concepts pretty straight forward Lots and lots of permutations

N fixed and remaining after harvest

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) N fixed N after harvest (including roots)

Compendium of international figures

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What causes the variability

Fixing N is very hard and very energy intensive Legumes are lazy They wont fix N, if there is available soil N If there is little soil N, they will fix N flat out Biologic zero – soil temperatures

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N catch crops

It is easy to loose 50 – 100 kg N / ha over autumn- winter-spring when leaching is high Quite possible to catch 50 - 100 kg N / ha over autumn-winter-spring with catch crops Mustard and cereals are the best Need to be well established before N leaching

• ccurs

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Growing catch crops & green manures

Where?

– Undervine – Interrow – Both

What kind?

– Perennials – Annuals

When

– Summer – Autumn – Winter – Spring

http://www.sare.org/Learning-Center/Books/ Managing-Cover-Crops-Profitably-3rd-Edition

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OSCAR

Optimising Subsidiary Crop Application in Rotations www.covercrops.eu

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Wrapping up N

You need to understand the N cycle and how N behaves in the soil Importing N is expensive in organics Fix your own is the best and cheapest long term option (Un)fortunataly the options and permutations are many - and

• ften highly site specific

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Stop Treating Soil Like Dirt Zespri Soil Workshop 2019 Part 4: Soil Health

Dr Charles ‘Merf’ Merfield MRSNZ charles@merfield.com

The Future Farming Centre

Permanent Agriculture and Horticulture Science and Extension www.bhu.org.nz/future-farming-centre

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Soil health = soil biology

Soil health is physical, chemical and biological / ecological – all are required But soil biology is a key driver of physical and chemical health Physical and chemical health is the foundation for biological health A healthy soil is a biologically active soil How to make a soil biologically active?

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163 pages

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http://www.bhu.org.nz/future-farming-centre/future-farming- centre/information/bulletin/2013-v1/make-soil-organisms-work-for-you-mythbusting- practices-that-do-and-don-t-work

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The living soil

Soil is the most complex ecosystem on the planet It is typically 10 times as complex and contains 10 times the amount of life (weight and species) than the above ground biomass Looking after all this complexity is surprisingly straight forward

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Looking after your soil

Your soil Feed Organic matter

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Soil fodder

Fresh plant residues, animal dung and dead animals (freshly dead, living things) Diversity is the spice of life, and it makes for a healthier soil - the more diverse the ‘fodder’ the better the soil will be The more the merrier (unlike people) more fodder (in situ production) is better than less

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The Jena Experiment

Why ecosystems need biodiversity

www.the-jena-experiment.de www.the-jena-experiment.de

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Living plants = soil armour

A diverse, living, ground cover of plants Living plants join the pedosphere and atmosphere into a single continuum…

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Living plants join the sky and soil into a single continuum

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Living plants = soil armour

It’s not just leaf fall – plant roots are actively moving energy and photosynthates into the soil Highly complex food webs – esp. with mycorrhiza A diverse, living, ground cover of plants vital for a healthy soil

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What ‘kills’ soil biology?

Way back in the first presentation:

– Machinery, animal and human compaction – Cultivation / tillage – Lack of living plants - ‘ground cover’ / living mulch

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What ‘kills’ soil biology?

Long term trial at Plant & Food Land had been in pasture >15 years Run for 11 years Five treatments

• Continuous grass pasture
• No till: No cultivation, direct drilled
• Minimum tillage: Disc, harrow, roll x 2
• Intensive tillage: Plough, maxi-till, harrow, roll x 2
• Continuous herbicide fallow

http://dx.doi.org/10.1071/SR14173

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Amount of soil carbon loss relative to pasture after 11 years

17 15.9 16.9 24.2 5 10 15 20 25 30

Pasture No till Min till Intensive till Herbicide fallow Soil carbon tonnes / ha

Dr Mike Beare et al. Plant & Food Research

Multiply C by 1.72 = organic matter

OM=29 OM=27 OM=29 OM=42

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Effect of herbicides on soil structure

Harvest Year

2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012

Structural Condition Score (1-10)

1 2 3 4 5 6 7 8 9 10

Pasture No-till Min-till Intensive till

• ---- Optimum range ------

Fallow

Dr Mike Beare et al. Plant & Food Research

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Lack of ground cover is ‘kills’ soil

Bare soil = ‘dead’ soil Loss of soil C = climate change impact Loss of soil and above ground biodiversity Physical loss of soil, esp. on slopes Loss of N and P -> freshwater Organic options are not necessarily better, cultivation is likely worse > min-till + fallow = ☠!

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Over in viticulture…

John van der Linden ex Villa Maria

“The death zone has gotta go”

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Soil health – in one page

Physics

– Don’t compact it – Don’t till / cultivate it

Chemistry

– Optimum nutrient levels

Biology / ecology

– Fresh dead stuff – Diversity of fresh dead stuff – The more fresh dead stuff the better – Soil amour – a continual covering of diverse living plants

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Available from the FFC Bulletin Issue: 2019 V4 October

Thank you.