Soil and Fertility
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Transcript of 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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April 11 BASIL3
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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April 11 BASIL5
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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April 11 BASIL6
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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April 11 BASIL10
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
April 11 BASIL13
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Experimental Evidence
April 11 BASIL14
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Hyphal Network VAM Fungi
April 11 BASIL15
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Vesicles-VAM Fungi
April 11 BASIL16
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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