Soil Physical Chemical Quality 08

7/31/2019 Soil Physical Chemical Quality 08

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Hailin Zhang

Department of Plant and Soil Sciences

Oklahoma State University

Soil Physical and Chemical

Quality and Management inOrganic Production


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What makes up soils?

Water

25%

Air

25%

OM2%

Mineral

48%

SandSiltClay


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Soil Is a Living Body

US


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Soil Properties

Physical

TextureStructure

Chemical

Fertility

pH

Soluble salts

Biological

Microorganism population-life in the soil


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Clay

Silty ClaySandy Clay

% Sand

LoamySand

SandyClay Loam

Sandy

LoamSand

Silt

Loam

Clay Loam

Loam

Silty ClayLoam

Silt


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Water holding capacity andmovement

NRCS


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Improving Soil PhysicalCondition

Adding organic material

Adding gypsum for alkali soils


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pH and Buffer Index

Soil pH is a measure of the acidityand alkalinity of the soil;

Nutrient availability is related to pH;Crops can only grow well in certain

pH ranges;

Liming is the most economical andeffective method to raise soil pH


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pH valuedefinesrelative

acidity orbasicity

9.0

8.0

7.0

6.0

5.0

4.0

Very strong

Strong

Medium

Moderate

Slight

Slight

MediumStrong

Basic

Acid

Pure wate

Mostproductivesoils

VinegarLemon juic

Ammoniacleaner


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Apply limewell ahead of planting to

correct soil acidity


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N Ca

P Mg

K S

16

Essential

Elements

C H O

B Cl Cu Fe

Mn Mo Zn

Essential Plant Nutrients


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Negatively Charged Colloids

Attract Cations

K+

Ca++

Na+

Ca++

H+

Mg++

-

--

-

--

---

Soil Colloid


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Clay and Organic Matter Have

Greatest Influence on CECClay

10-150meq/100g

Organic matter

200-400meq/100g

Organic matter has a higher CEC

(cation exchange capacity)


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Nutrient balance is the key forsuccess

Rightnutrients

Impropernutrients


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Soil Soluble Salts Affect Plant Growth

Normal

EC (mmhos/cm)0 4 8 12 16

15

ESP%

Saline

Sodic

Increased salt hazard

30

Saline-Sodic


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Over Fertilization

Salts build up in thesoil

Alters soil pH

Unbalanced growth More vegetative, less

reproductive growth

More disease and

less winter hardy
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Soil Tests Serve

Two Basic Functions

Provide a starting point fordeveloping fertilizer and limingprogram

Monitor nutrient level to keep thefertilizer program on track


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OSU Cooperative Extension

Soil Probe

Get a Useful Sample

Clean Bucket

Right Depth(plow layer or 6inches

15-20 cores


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Soil Tests at OSU

RoutinepHBuffer IndexNitrogen

PhosphorusPotassium

Secondary NutrientsSulfurMagnesiumCalcium

MicronutrientsIronZincBoron

Soil Organic Matter, Soil Texture, Soil SalinityCompost, Animal Manure, Irrigation Water


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Summary

Soil properties are important for plant growth There are 16 essential plant nutrients

Soil testing is important for successfulorganic production

An representative sample is needed toensure reliable test results

Balanced fertilizer program is critical


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Soil, Water and Forage AnalyticalLaboratory

http://www.soiltesting.okstate.edu
http://www.soiltesting.okstate.edu/http://www.soiltesting.okstate.edu/

Documents

Soil Physical Chemical Quality 08