Soil and Fertility

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Soil & Fertility


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April 11 BASIL2

Introduction

Conventional agriculture deals with soil chemistry

ratherthanthe soil biology Conventional agriculturethinks ofsoil as littlemore

thanananchorfor plants

BD thinks ofsoil as a living/breathingentity

BD focuses on soil health ratherthan planthealthand hencetaking careofthe soil is giventhehighest

priority


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Is Soil Living

Has Digestive System

Composting/Decomposition

Has Respiratory System

Soil breathes (aerobic processes)

Has Reproductive System

Every 100 years 1 inch layeroftop soil is

generated


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April 11 BASIL4

Soil Formation

Mother rock broken down by the chelatingactionoffungi and algaethatgrow inthe cracks

Plant roots further breakthe soil

Process takes millions ofyears

Earth is a blue planet i.e. primarily covered by water.Relatively small land areaand avery thin layer

(topsoil) availableforgrowingfood


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Basic Components of Good Soil

Minerals (45% by vol.)

Primary minerals in parentmaterial (rocks) &secondary compounds formed by these

Air 25%

Water 25%

Organic Matter (2% - 5% by vol.) In Punjab, Organic Mattertoday is less than 1%

compared to 5% beforethe Green Revolution


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Soil Characteristics

Useful to determine whatkind ofsoil wehave

onourfarms Soil Colour

Determined by the colourofthe primary minerals and

their compounds

Soil Texture Relative portions ofsand, silt & clay

Soil Structure

Aggregationofsoil particles


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Soil Colour

Colour duetothe primary minerals and the

secondary compounds present inthe soil Red Secondary compounds of iron

Black Secondary compounds of

manganese, sulphurand nitrogen


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Soil Texture

Mineral partmadeof3 distinct particle sizes

Sand - Largest; Quartz; No Nutrients;Cannothold water;Heats &

Cools very fast Silt Medium;Mostly Quartz but smaller;

Clay Smallest;Holds appreciablenutrients and water

Texture is the relative portions ofSand, Silt & Clay

Coarsetextured Finetextured

Sand

Loamy Sand

Sandy Loam

Fine Sandy Loam

Loam

Silty Loam Silt Silty Clay Loam Clay Loam Clay

Does not change withagricultural activity


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Soil Structure

Structure refers totheaggregation (clumpingtogether) ofsoil particles into larger secondaryclusters

Good structure when soil crumbles easily in yourhand

Structure improves when it contains organic material

& humus Can be improved/destroyed by choiceand timingof

farm practices


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Organic Portion of Soil

Contains dead organisms, plantand organic

materials invarious phases ofdecomposition Contains Humus Relatively stableorganic

matter

Contains a livingeco-systemofmicroand

macroorganisms


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Organic Portion - Humus

The relatively stableorganic matter (steady state)

Made up ofdark coloured organic matter infinal stages of

decomposition Formed by gummy/gluey substances the by-products ofthe

decomposition

Gives lightness tothe soil and improves aeration

Chelatingacids are presentthat dissolveminerals inthe soiland putthem ina colloidal statemakingthemavailabletothe

plants Helps build soil structure becauseofcementingofthe soil

particles/aggregates by thegummy/gluey substances

Canhold watervery efficiently


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Organic Portion Living EcoSystem

Contains enormous diversity ofmicro/macroorganisms Bacteria nitrogenfixers; phosphor solubilizing; releasegrowthhormones;

Actinomycetes releaseantibiotics

Fungi mycorhyzzia & theirhyphaeextend the reachofthe roothair Cyanobacteria & Algae produceownfood via photosynthesis; produceglue

Protozoa feed on bacteria & provide soil nutrients after death

Nematodes Microscopic round worms;eat decaying litter, fungi etc.

Earthworms The best labourers one canhave. They work day and nightand eat dirtfora living. Tunnels aeratethe soil. The

casts are rich innutrients.

Termites Thehealthofafarm can bemeasured by thenumberofanthills onthat farm. Break downthe cellulose

Manure Worms/Grinders etc. - Efficient Shredders

These living systems arethetrue builders and keepers ofthefertility ofthe soil Store & upontheir death releasethenutrients

This slow/controlled releaseofnutrients leads to less leaching

Convert bound up minerals into plantavailableforms

Interact withoneother inamillion different ways inthe soil ecosystem

Convert N2 to Nitrates; Sulphurto Sulphates & soon


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Soil Testing Taking Samples

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Experimental Evidence

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Hyphal Network VAM Fungi

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Vesicles-VAM Fungi

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Effects of Modern Agricultural

Practices on the Soil Ecosystem

Tractors compactthe soil and the ploughingthatfollows creates atalcumpowder consistency

Soil gets blownaway easily and with itthefertility and the wealthofthe land

Farmers most precious capital thus gets eroded

Thefertilizers & pesticides causethemicro/macroorganisms inthe soil to die

Soil loses its vitality and lifeand it becomes littlemorethanananchorforthe plants

The practiceofnot returningtheorganic matter backtothe soil severelydepletes thehumus inthe soil

Soil cannot retain waterefficiently

Thefarms waterneeds (and hencetheexpenses incurred) increase substantially

Thenutrients leachmoreeasily eventually pollutingand poisoningour water systems

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Soil and Fertility