Soil Health – An OverviewDr. M. DhakshinamoorthyProfessor of Soil ScienceTamil Nadu Rice Research Institute,Aduthurai
What is meant by the word “Soils”?Soil is one of the most important earth materials weencounter each day, but the definition of soil isdifficult.Soil Scientists (and most ordinary people): • fine-grained, well-weathered earth material that is able to support plant growth • focus on the physical and chemical propertiesEngineers: • any earth material that can be removed without blasting • focus on particle size and the amount of organic material • engineering applications
Soil defined as“Soil is a natural dynamic bodydifferentiated into horizons of variabledepth which differ among themselvesand from the parent material below inmorphology, physical properties andconstitution, chemical properties andcomposition and biologicalcharacteristics” (Joffee)
The soil is teeming with life. It is a world ofdarkness, of caverns, tunnels andcrevices,inhabited by a bizaree assortment ofliving creatures J. A. Wallswork
Some Facts about soil1.Soil is not dirt2.Soil is not inert3.Soil is dynamic4.Soil is a three dimensional body5.Soil is a three/four phase system
Leaching takes minerals carried by water to the subsoilHumus givesthe topsoil arich browncolor D
In the A horizon,water percolatesdownward andcarries minerals asit goes. This iscalled “leaching.”Leaching carriesminerals downinto the lower soilhorizons.
The B-Horizon is called thesubsoil.This horizon is where theleached minerals fromhorizon A end up.These leached minerals maycolor the subsoil. Forexample, the presence of ironmy color the subsoil red.Horizon B-Zone of Accumulation of leached minerals
The C-horizon is called thezone of weathered bedrock.When you have a residual soil,one formed over the originalbedrock, the C-horizonresembles the bedrock, but itis weathered.In a residual soil, the bedrockis below the C-horizon.Remember that the CoastalPlain does not have bedrockunder the soil profile, but ithas layers of sand, clay andgravel. That is because of thesea level changes over timeand the rivers that flowed overit.
Goods and Services provided by Soil Human Health Air Biomass Production (e.g. food chain) Culture Open Water Biodiversity Soil Ground Water
S O I Black Soil L Alkali Soil S O F I Red SoilSandy soil N D I A
Soil TaxonomyEntisols - soils with little or no morphological developmentVertisols - clayey soils with high shrink/swell capacityInceptisols - soils with weakly developed subsurface horizonsAridisols - CaCO3-containing soils of arid environments with moderate to strong developmentMollisols - grassland soils with high base statusAndisols - soils formed in volcanic ashSpodosols - acid soils with a subsurface accumulation of metal-humus complexesAlfisols - soils with a subsurface zone of silicate clay accumulation and >35% base saturationUltisols - soils with a subsurface zone of silicate clay accumulation and <35% base saturationOxisols - intensely weathered soils, tropical and subtropicalHistosols - organic soils (peak, bog, muck)Gelisols - soils with permafrost within 2 m of the surface
Soil HealthSoil health, provides an overall picture of the condition of manyproperties and processes; the terms soil health and soil quality canbe used interchangeably.Soil health or quality is the soils fitness to support crop growthwithout resulting in soil degradation or otherwise harming theenvironment.Soil quality changes slowly because of natural processes, suchas weathering, and more rapidly under human activity; land useand farming practices may change soil quality for the better orfor the worseSoil health deteriorates mainly through erosion by wind andwater, loss of organic matter, breakdown of soil structure,salinization, and chemical contamination.
Assessing Soil QualityHuman Health – Physical functions, Mental capacity, Emotional well– beingSoil Quality – Physical, Chemical and Biological properties of the soil – Soil Texture, Structure, Water holding capacity,pH, EC, CEC, etc.
Elements of soil qualitySupport Plant Growth – Soil Fertility vs ProductivityWater storage and supply – Minimum surface runoffEnvironmental buffering – reduce toxicity of some elements
Plant growthA good-quality soil is both tillable andfertile.provides a suitable medium for seedgermination and root growthsupplies a balance of nutrients to plantsreceives, stores, and releases moisture forplant usesupports a community of microorganismsthat recycle nutrients through decompositionand help plants to resist disease.
Water regulation and partitioningPercolation – EntryInfiltration – Downward movementSeepage – Lateral movementRunoff – Overflow A good quality soil must reduce surfacerunoff, deep percolation and infiltration intogroundwater and stores enough water topromote optimal crop growth.
Environmental bufferingAccept and hold nutrients and release them asrequired by plantsBreak down harmful compounds intosubstances that are nontoxic to plants andanimals and do not pollute surface water andgroundwater.
SPLASH EROSIONSoil Surface just beforerain drop impact Soil Surface after Rain drop impact
WIND EROSION SUSPENSIONW IN SALTATION D CREEP SALTATION DETACHES PARTICLES SMALLER PARTICLES SUSPENDED LARGER PARTICLES CREEP SANDY AND SILTY SOILS MOST SUSCEPTIBLE SOIL ACCUMULATION IN DITCHES AND FENCE ROWS
LOSS OF SOIL ORGANIC MATTERSoil ErosionMicrobial OxidationIntensive CultivationArid and Semi Arid ClimateLack of organic manure additionRemoval of stocks and/or burning
Deterioration of Soil StructureSoil Erosion – Break down of Soil AggregatesPhysical Degradation – use of heavy implementsChemical Degradation - Irrigation with Poor QualityWatersIntensive Mono – crop Cultivation
SOIL CONTAMINATIONIndiscriminate use of Pesticides and Inorganic FertilizersAccumulation of solid waste, is a major problem indeveloping countries like India where the garbage and refuse products are not degradedRadioactive substances from nuclear plants which arereleased into the soil andIndiscriminate discharge of industrial effluents on landAnd water bodies
Consumption of pesticides in important states of India Gross cropped area Consumption of Consumption of State pesticide (MT) pesticide (g ha-1) Andra Pradesh 12,783 7000 548 Gujarath 11,188 5000 447 Karnataka 12,013 2600 216 Madhya Pradesh 24,689 1299 53 Maharastra 21,418 3942 184 Orissa 9,724 1006 103 Punjab 7,693 7100 923 Rajasthan 20,380 3300 162 Tamil Nadu 7,113 2882 (Agnihotri,2000) 410
Persistence of pesticides in soilPesticides Months (95% disappearance)Aldrin 24Heptachlor 8BHC 18Parathion 3Phorate 3Carbofuran 3CarbarylDisulfaton 4
Metal content of some rock phosphates (mg kg-1) Rock phosphate Zn (mg kg-1) Cu (mg kg-1)Mussoorie 100 115Jhamarkotra 200 129Kasipatnam 100 190Purulia 350 140 Buyanovsky et al. (1990)Udaipur 75 85
Content of some heavy metals in imported rock phosphates (mg kg-1) Rock Cd Hg Pb Ni Zn As phosphateMorocco 18 0.04 2 30 270 10Florida 5 0.09 12 13 80 5Tunisia 34 0.03 2 16 290 2 FAO, 1975Senegal 71 0.33 4 53 500 2USSR 0.2 0.01 4 0.5 20 <1
Cd concentrations in phosphate fertilizers (mg kg-1) Country Range Canada 2.1 – 9.3 Australia 18.0 – 91 USA 7.4 – 156 Netherlands 9.0 – 60.0 Tiller, 1983 sweden 2.0 – 30.0
Heavy metal contents (average) in fertilizers Fertilizer Heavy metal (mg kg-1 fertilizer) Cu Zn Mn Mo Cd PbSingle super phosphate 26 115 150 3.3 187 609Diammonium phosphate - - - 109 188 -Muriate of potash 3 3 8 0.2 14 88Ca-ammonium nitrate 0.2 6 11 - 6 200Urea 0.4 0.5 0.5 0.2 1 4Ammonium sulphate
Industrial EffluentsS. Size of Industrial Number of Red AlertNo. Unit Units Units1. Large Units 700 4502. Medium units 2200 1000 The Hindu, 19973. Smaller Units 14000 6500
Industrial unitsIndustrial Unit PollutantThermal Power Heavy MetalsPaper High pH, BOD and CODRubber High salt, Chlorides, High pH, BODSteel Acids, Phenols, Cyanides, Low pH, Oils, Fe saltsTextile Sodium salts, Organic Compounds, High pH, FibresOil Refineries Acids, Bases, Resins, Phenols, Petrochemicals
Industrial unitsIndustrial Unit PollutantOrganic Chemicals Toxic Compounds, Phenols, High/low pHExplosive Chemicals Alcohol, Heavy Metals, Organic CompoundsFertilizers High pH, Heavy Metals, Fluorides, Ammonia cpdsCement Dust, Sodium salts, High BDFood Industries High BOD and COD, Organic compoundsSoap Acids, Fats, Glycerol, Phosphates, S hydrocarbons
Content of Toxic heavy metals (mg kg-1) in Punjab Fe Zn Cu Pb Ni As CrHighly industrialized 6.2 0.68 0.94 0.053 0.14 1.38 0.189Less industrialized 0.15 0.24 0.26 0.032 0.004 0.23 0.004 Source : Khurana et al. (2003)
Heavy metal characterization in various industrial effluents S1- Sewage water ; S2 - Electroplating ; S3 - Textiles ; S4 - Dying ; S5 – Foundry 70.0 60.0 50.0 -1 ) 40.0 Sewage 30.0 m C L g n o e ( t 20.0 EP Textiles 10.0 Dye 0.0 Ni Pb Cd Cr Cu Zn S1 S2 S3 S4 S5
Range and mean values of the total heavy metal content of the soil collected from Erode Place of soil Concentration (mg kg-1) collection Cr Ni Range Mean Range MeanRN Pudur 126 – 468 261 96– 187 141Agraharam (Big) 288 – 446 322 73 – 176 116Agraharam (Small) 98 – 156 103 66 – 178 125
Heavy metal content (mg kg-1) of soils treated with sewage and solid waste around HyderabadHeavy metals Normal soil Treated soilLead 5.0 170.0Nickel 2.0 10.0Cobalt 5.0 7.0
TANNERY INDUSTRY WASTEIndia is the major exporter of processed leathers.Animal skins and hides are converted into non-biodegradable, stable andquality leathers through a process known as tanning.This process includes dehairing, removal of flesh and fat, and treatmentwith either plant extracts (vegetable tanning) or chemicals (chrometanning).Several chemicals, including salts and heavy metals, are used inchemical tanning.Such process results in large quantities of solid waste (sludge).It is estimated that annually more than 1,24,400 tonnes (dry weightbasis)oftannery sludge are produced from 1008 small and 75 large tanneries inIndia.
STATUS OF TANNING INDUSTRIES IN INDIAIt is estimated that tanning industry wastes have already contaminated over50,000 ha of productive agricultural land.In chrome tanning, 276 chemicals and 14 heavy metals are used.It is estimated that approximately 32,000 t of basic chromium (cr) sulfatesalts are used annually in Indian tanneries. This amounts to an annual loss of nearly 2000-3200 t of Cr (on anelemental basis).The concentration of Cr in the effluents from the chrome tanning yard is inthe range 2000-5000 mg L-1.International regulations stipulate that the Cr concentration in industrialwaste shall not exceed 2 mg L-1.
Salt and heavy metal content of tannery sludge Location pH EC Na Cr Cu Zn (H2O) (dSm- (mg kg-1) (mg kg-1) (mg kg-1) (mg kg- 1 ) 1 )Ambur 7.95 12.5 49451 5406 42 121Vaniyambadi 8.11 4.0 10021 1605 19 54Vaduganthangal 8.46 8.3 12231 8241 42 67Pernampet 7.70 20.8 29239 16158 32 51
Heavy metal content (ppm) of the soil treated with different dilutions of tannery effluent Treatment Zn Cu Fe Mn Cr 100% effluent 2.2 1.2 5.4 6.2 0.17 50:50 effluent:water 2.3 1.3 5.8 0.6 0.15 33:67 effluent:water 2.2 1.3 5.6 7.2 0.12 25:75 effluent:water 2.2 1.3 5.6 6.6 0.99 20:80 effluent:water 2.4 1.4 5.4 8.8 0.12 10:90 effluent:water 2.5 1.4 6.8 8.8 0.10 Control(water alone) 2.6 1.6 7.2 10.0 0.02
DISTILLERY SPENT WASHMore number of sugar factories in the country, more and morefactories producing alcohol are being established.Molasses, containing 8 per cent of sugar, serves as a cheap sourceof raw material for the production of alcohol.Every Lit of alcohol, nearly 12 to 14 Lit of effluent is discharged.Each unit is discharging 5 to 10 lakh Lit of raw effluent every day.Sakthi Sugars Distillery Unit discharged 10 lakh Lit of effluent/ day.The primary treatment plant the BOD has been reduced from45,000 to 4,500 ppm and COD from 1,00,000 to 35,000 ppm.These values are found to exceed the limits prescribed by PCBnorms.
SAGO FACTORY EFFLUENT Most of the sago factories in India are concentrated inTamil Nadu. Out of 800 sago factories in Tamil Nadu, 650 are located inSalem district. A Sago factory with a capacity to produce 3,500 kg starchper day, uses 110 m3 to 115 m3 water per day. Of this, 95-100 m3 (nearly 87%) water comes out as wastewater after processing. Because of the starch content in the waste water, themicrobial activity is more in the stagnated waste waterresulting in unpleasant odour (Balagobal et al., 1977).
SAGO FACTORY EFFLUENT (Continued)Sago factory effluent contains appreciable quantitiesof TSS and is acidic in nature with high EC.High amounts of P and K and moderate level of Nwith very low quantities of trace elements.Sago factory waste water irrigated soils have lowerapparent and absolute specific gravity and waterholding capacity and has slightly higher porositythan the corresponding control soil. Balagobal et al., 1977
TEXTILE INDUSTRY EFFLUENT Processing such as boiling, bleaching, dyeing, sizing desiringmercerizing, printing and finishing which can let out copious quantitiesof waste waters and sludges which are usually dumped on river beds aswell as on public areas. Accumulation of such waste material slowly create environmentaldegradation on soil ecosystem, ground water status and crop stand andits yield potentials. For Colouring the textile materials several dyes and colouring agentswere used Textile mills require large quantity of high degree pure water and alsothey discharge high volume of wastewater. The land and water and the ecosystem located on the Cauvery riverarea and its tributaries Bhavani, Noyyal are adversely affected.
Causes of Acid Rain• The principal cause of acid rain is from human sources – Industrial factories, power-generating plants and vehicles – Sulphur dioxide and oxides of nitrogen are released during the fuel burning process (i.e. combustion) MSN Encarta
NITRATE POLLUTION OF GROUNDWATERPollution of groundwater from fertilizer N is caused by leaching. The magnitude of loss depends upon soil conditions, agriculturalpractices, agro-climatic conditions, and type of fertilizers and methodsof application. The time taken by nitrate to move from the root zone to the watertable, therefore, varies considerably. In sandy soils with high water table and high rate of fertilizerapplication, it may reach the water table in matter of days whereas inheavy soils, low rainfall and low rate of application with deep watertable, it may take years. Two main alleged health hazards are blue baby disease of youngbabies and cancer due to nitrate ingestion in food and water. World Health Organization (WHO) recommends that drinking watershould not contain more than 50 mg NO3 – L-1.
ENVIRONMENTAL PROBLEMS RELATED TO FERTILIZER USE, THEIR MITIGATION STRATEGIES AND IMPLICATIONS IN INDIAEnvironmental Causative mechanism Mitigation Seriousness of the problem and impact strategies problem in IndiaStratospheric Nitrous oxides from Use of Emission fromozone burning of fossil nitrification, soil is lowdepletion and fuels by industry, urease compared toglobal climate automobiles andchange from denitrification inhibitor, countries of nitrate in soils increasing where are transported to fertilizer use fertilizer N the stratosphere efficiency, use is higher where ozone avoid destruction occurs; ultraviolet radiation intermittent incident on earth’s wetting and surface increases, drying in rice
What we know about GW• CO2 content of the air has increased from 280 to ~360 PPM since the industrial revolution.• Average world temperatures have risen by around 0.5 centigrade in the last 100 years.• The levels of CFCs, nitrous oxide and methane have also increased in the upper atmosphere.• The ozone layer above the poles continues to thin.• The world’s forested area has shrunk by more than 50% in 100 years.• The last 20 years has been dominated by a series of record climatic highs.• Sea levels have risen 1 foot in the last 100 years and alpine glaciers are shrinking/retreating rapidly.
Anthropogenic greenhouse gases in the atmosphere. (Source:Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory.)
Nutrient Mining in IndiaRemoval of nutrients 28.5 M. TonnesAddition of nutrients 18.5 M. TonnesDepletion 10.0 M. TonnesIn Tamil NaduRemoval of nutrients 9.14 lakh tonnesAddition of nutrients 7.91 lakh tonnesDepletion 1.23 lakh tonnesFertilizer consumption in T.N. 157 kg ha-1National consumption 971 g ha-1 (Fert. News, April 2001)
Extent of Nutrient Deficiency (%)Nutrient India Tamil NaduNitrogen 100 100Phosphorus 98 85Potassium 30 40Sulphur 18 20Iron 12 17Manganese 5 6Copper 3 5Zinc 50 60
Nutrient Use Efficiency in India Nutrient Efficiency (%) Nitrogen 30-50 Phosphorus 15-20 Potassium 50-60
Soil Health care – Issues and Strategies IssuesIssues StrategiesSOIL SOIL HEALTH CAREDEGRADATIONIndustrial wastes Scientific and TechnicalPesticides ManagementFertilizers PhytoremediationSewage INM, IPM. ISFM etcRadionuclides Alternative croppingBiotic interference Regular monitoringSalinisation Decision SupportWaterlogging Systems Increasing awareness
Integrated Nutrient ManagementWhat is INM?Integrated use of all available resources – Fertilizers,Organic and Green Manures, Biofertilizers, Crop Residues,Agricultural and Industrial WastesWhy INM?To effectively utilize all the available resources and bridgethe gap between the requirement and availability offertilizers and thereby reduce the cost of cultivation
Estimates of the availability of some crop residues in India and their plant nutrient potential Crop Residue Nutrient Nutrient potential (000 t) yield (000 t) N P2O5 K2O Total Utilizable Fertilizer equivalent Rice 1,10,495 0.61 0.18 1.38 2,398 799 399 Wheat 82,631 0.48 0.16 1.18 1,504 501 250 Sorghum 12,535 0.52 0.23 1.34 262 87 43 Maize 11,974 0.52 0.18 1.35 252 84 42 Pearl millet 6,967 0.45 0.16 1.14 121 40 20 Barley 2, 475 0.52 0.18 1.30 51 17 8
Nutrient potential of harvest residues in Tamil Nadu Residue yield Nutrient potentialCrop N P2O5 K2O --------------------------------------(lakh tonnes)---------------------------Rice 90.92 0.53 0.21 1.51Sorghum 8.50 0.05 0.02 0.16Pearl millet 5.08 0.03 0.01 0.11
Nutrient potential of urban and Agro- industrial wastes in Tamil NaduWaste Quantity Nutrient potential N P2O5 K2O -------------------------------(lakh tones or * litres )-----------------Pressmud 3.0 0.04 0.05 0.02Sugar mill 30.0* 0.06 0.02 0.33effluentRaw coir pith 2.8 0.007 0.001 0.022Sewage sludge 2.6 0.09 0.04 0.07
Animal manure and its nutrient potential in Tamil Nadu Wet Urine Nutrient potential Animal Dung N P2O5 K2O -------------------------------(lakh tones)---------------Cattle 827 354 1.95 0.87 1.12Sheep & 44 22 0.62 0.10 0.66Goat
Composting technologies available and developed at TNAU 1. Preparation of coirwaste compost usingyeast sludge 2. Rapid composting technology for sugarcanetrash using yeast sludge 3. Alternate method of sugarcane trashcomposting 4. Vermicomposting technique 5. Farm waste composting 6. Urban solid waste composting 7. Bio-compost from bagasse based pulp andpaper mill
WARNING PL…….. UPON THIS SOIL OUR SUVIVAL DEPENDS HUSBAND IT AND DO NOT ABUSE IT