LA Master Gardener

Soils, Soil Moisture and Nutrition

Chapter 5 J Stevens

Associate Professor/SpecialistSoil Fertility/Nutrient Management

Still daylight in California.

Did You Read Chapter 5?If so, do you have any “burning”

questions?

This presentation is a combination of information from 4-5 courses in Soil

Fertility,Advanced Soil Fertility, Micronutrients,

Soil Chemistry, and Soil Classification.

Soil Fertility is actually Soil Chemistry.

So, What is Soil?

A living dynamic resource that supports plant

life.

Contains mineral particles, organic matter, air,

water, and organisms.

Biological, chemical and physical properties that

are always changing.

Soil CharacteristicsA medium in which plants grow.

An ideal garden soil is fertile, deep, easilycrumbled, well drained and fairly high in

organicmatter (O.M.)

Soil fertility is vital to a productive soil. A

fertile soil is not necessarily a productive soil.

Poor drainage, insects, weeds, drought and other

factors can limit production, even when fertility is

adequate.

Soil Composition

Soil is made up of:Mineral matter- sand to clay 45%Organic matter 5%Water - in the pore spaces 25%Air - in the pore spaces 25%

These are the proportions in a loam-textured

soil & they vary from time to time and place to

place.

Soil Formation The exposed surfaces of rocks,

gravel,sand and silt particles are constantlybeing broken down by physical andchemical weathering.

As soils are formed during the weathering

process, some minerals and organicmatter are broken down to

extremelysmall particles.

Important Physical Properties of SoilColor- determined by O.M., drainage,

and degree of oxidation/weatheringTexture- amounts of different sized particlesStructure- arrangement of soil

particles into aggregatesDrainage- water movement in/on the

soilSoil Depth- vertical distance into a

soil to layer that restricts root

growth

Soil Color- GeneralizationsLight (topsoil) - low O.M., coarse texture, leached

Dark (topsoil) - more O.M., could be parent

material

Red/Brown (subsoil) - relative free movement

of water and air

Yellow (subsoil) - drainage impediment

Gray (mottling) - too much water/ too little air

Poor drainage - notice the gray color

O

High water in bed – notice the plasticNot a desirable situation!

O

Soil TextureRelative amounts of sand, silt and clayRefer to the soil textural triangle (Figure

5-2)

Sand is the coarser particles, feel rough when

rubbed between the thumb and fingersSilt when dry feels smooth/floury; wet-

smooth,not slick or stickyClay particles are fine textured. Smooth

whendry; slick and sticky when wet

Eight or nine textural classes generally used.

Soil Textural Triangle

Notice the direction of the arrow

Maui Gulf of Mexico White SandsNew Mexico

Sand

Clay

Structure of Clay,1:1 non-expanding lattice clay

Structure of Clay, 2:1 expanding lattice clay

Soil StructureRefer to Table 5-1Arrangement of primary soil particles intoaggregates. Principal forms are- platy,prismatic, columnar, blocky and granular.Structure is closely related to air and

watermovement. Water, air and plant roots

movemore freely through soils that have blockystructure than those with platy structure.

Watercan enter a soil with granular structure

morerapidly.

MulchingSimply placing a layer of organic or

inorganicmaterial on top of the soil. Shredded pine

barkor compost can reduce extremes in soil temperature and moisture levels. Dense

mulchcan be effective in controlling weeds.

Mulch that decomposes can be incorporated

into the soil to improve soil structure, water

holding capacity, rainfall infiltration, and raise

soil nutrient levels.

What is Composting?Composting occurs naturally nearly everywhere! Leaves

drop, grassclippings after the lawn is cut, plants and animals die.

Over time, these organic materials breakdown and decompose.

The rich, dark, soil-like material that results is called compost.

Microorganisms such as bacteria and fungi and small soil animals

do much of the work in breaking organic residues down to form

compost.

Microorganisms use the organic materials as food sources.

Nutrients are released back into the soil, to be used by plants.

This is nature’s way of composting and recycling!

Why Compost?You can help the composting cycle work even better than

innature. The organic waste you put back into the soil can be

usedby other things.

Instead of it going to a landfill or garbage-burning plant, itbecomes a valuable resource.

Yard waste and food scraps account for 20 to 30 % of garbage. By

composting these organic materials you send less garbage to the

landfill.

Gardeners use compost, as it allows the soil to hold more water,

and it adds nutrients to the soil.

Flowers, vegetables, trees, shrubs, house plants, lawns and

container plants benefit greatly.

Best Ever CompostLike baking a cake- just follow the recipe! Add the ingredients,

stir, “bake” and out comes compost!

There are a few basic steps to follow. Here are the necessary ingredients

and general directions for composting:

IngredientsKitchen Compost Yard or Garden Compost Add a mixture of some or all of these ingredients

Vegetable peels and seeds Hay or straw

Eggshells Wood chips/sawdustFruit peels and seeds Weeds and other wastesNutshells Grass clippings & leavesCoffee grounds Manure (not dog/cat)

Other vegetable or fruit scraps Ashes, shredded newspaper

Do not add meat scraps, bones, dairy products, oils or fats- Attract pests.

Directions1. Choose a composting bin; buy one for $$ - $$$ or make one.2. Place kitchen or yard waste in the bin; chop or shred

organics.3. Spread soil or “already done” compost over the pile This

layercontains the microorganisms that do the work; can do this in layers.

4. Adjust the moisture. The materials should be damp to the touch,but not so wet that drops come out when it’s squeezed.

5. Allow the pile to “bake”. It should heat quickly and reach a desiredtemperature of 90 to 160 degrees F in four to five days.

6. Stir the compost as it “bakes” if you want to speed the process.

7. The pile will settle down from its original height. This is good signthat the compost is “baking properly”.

8. If you turn or mix the pile every week, it should be done, or readyto use in 1 to 2 months. If you don’t turn it, the compost should be ready in 6 to 12 months.

9. Your compost should look like dark, crumbly soil; earthy/sweet.

10. Use the compost to mix into the soil to “feed” hungry plants.

Microbes Need a Balanced DietMicrobes normally live in the soil and eat small

tidbits oforganic matter where they get their nutrition.

They need carbon for energy and nitrogen to help build

their bodies. Carbon to Nitrogen ratio; C:N

Some wastes high in Carbon:Paper, sawdust, wood chips, straw, and leaves

Some wastes high in Nitrogen:Food scraps, grass clippings, legumes, and manures.

Be sure to include a mixture of wastes high in Nitrogen

in your compost pile.

Air, Water and WarmthMicrobes need oxygen, which if low, microbes

die-offand other microbes that don’t need oxygen

breakdownmaterial and give off nasty odors.

Compost piles should be as moist as a sponge that has

just been wrung out. If the pile is too dry, add water; if

too wet, add straw or dry sawdust to soak-up excess

moisture.

Microbes like temperatures of 90 to 140 degrees F. If

the temperature is too low, microbes will die-off and the

pile will take longer to reach the compost stage. Build

pile at least 3’ X 3’ X 3’ to help keep it warm.Shred the organic material, as it’s easier for

microbes to work with smaller pieces and decompose it

faster.

Which Composting System?System Used Cost Rate of

CompostingYard Waste

Compost mound None Slow not turned; fast

Holding unit Low SlowTurning unit High/Low Fast, minimum 6

wksCommercial bin High Fast, minimum 2

wksKitchen Waste

Garbage can Low Slow; faster if mixed

Worm compost bin Medium Fast, minimum 4 wks

Turning unit High Fast, minimum 6 wks

Kitchen/yard wastes combined may attract rodents.

Compost Pile Isn’t WorkingSymptom Problem How to Fix It

Pile is wet/ smells of Not enough air Turn the pile

rancid butter, vinegar, Too much N Add straw, sawdust,

and rotten eggs Too wet and chips

Pile doesn’t heat up Pile is too small Make pile larger

Pile is too dry Add water

Pile is damp and sweetsmelling, won’t heat up Not enough N Add grass

clippings or other sources of N

Center is dry, containstough materials Not enough water Add water and

turnPile attracts animals Meat and other Keep meat

and otheranimal products animal

products out;have been added enclose pile in

¼ inch hardware cloth

What To Do With My Compost1. Spread it on garden and mix it in with tillage.

2. Place or bury between the rows; roots will find nutrients.

3. In flower gardens, dig it in around the plants.

4. Use it as a mulch for shrubs, trees, and plants.

5. When transplanting, mix compost into the soil.

Don’t use compost to sprout tender seed. The seed may be killed by a fungus in the compost that causes a damping-off disease.

Organic Material vs. Organic Matter

Fresh/Partially decomposed OrganicMaterial:

Manures, grass clippings, leaf mold, oldsawdust and straw are good examples.

Broken down similar to composting, by micro-organisms in the soil, with adequate moisture, temperature, and nitrogen availability, to ultimately become Organic Matter (O.M.).

Soil Organic Matter Organic matter was once a living,

breathing organism, either plant or animal. Organic materials breakdown into humus under favorable temperature, oxygen and moisture conditions. What we measure in a soil sample as organic matter is the end product of decomposition. As earthworms, insects, bacteria, fungi and microbes feed on organic matter, nutrients are released that are available for use by growing plants.

Benefits of Soil Organic Matter

Improves soil physical condition, soil tilth

Increases water infiltration and water

holding capacityImproves soil structure and aerationStorehouse of plant nutrients - N, P,

S,Zn, etc.Increases exchange capacity

Cation Exchange One teaspoon of clay particles has a

surface area that will cover an acre of land. For the same measure, sand particles will have a surface area about equal to a sheet of paper in your manual.

The clay and organic fraction of the soil are referred to as colloids. These colloids have a negative (-) charge, attracting positively (+) charged particles.

This soil property is important, as it enables

a soil to hold positively charged nutrients;negatively charged nutrients will leach

throughthe soil.

Cation Exchange Capacity

The net total negative charge of a soil (or it’s capacity toexchange one cation for another) is referred to as cationexchange capacity, abbreviated as CEC.

Table 5-2 shows the CEC of soils from seven soil areas inLouisiana. Numbers increase with > amounts of clay.

Basic Cations include: Calcium, Ca ++, Magnesium, Mg ++, Sodium, Na+, Potassium, K+ and Ammonium, NH4

+

Acidic Cations: Aluminum, Al+++, Hydrogen, H+; maydominate exchange sites in highly weathered, acidic soils.

Selected Soil Areas in LASoil Area Soil Texture CEC

(meq/100 g)

Coastal Plains sl 4vfsl 6

Mississippi Terrace sil 8 – 10Coastal Prairies vfsl 8

sil 10cl 15

Miss., Red, Ouachita sl 4River Alluvial vfsl 8

sil 10 -15sicl/c 20/25

Clay or Organic MatterParticle(Colloid)

Ca++

- -Mg ++

- -Na +

-

- H+

-K+

-NH4

+- - -Al+++

NO3 -

HPO4-2

Lime reaction:

Step 1. Al +3 + CaCO3 + OH- ----> Ca +2 + Al(OH)2 + OH- + CO2

Step 2. H+ + OH- ----> HOH (pH goes up)

Cl-

SO4-2

Exchangeable Soil solution Fertilizer

(NH4)2SO4

NH4NO3

H3PO4

KCl

NH4+

K+

Na + Ca +2 Mg +2

Soil Water TermsGravitational water- available to plants

Capillary water- available to plants

Hygroscopic water- referred to as unavailable water.

Associated with soil moisture content at or below the

wilting point.

Field capacity- water a soil will hold against gravity

when allowed to drain freely.

Soil Moisture Storage

Figure 5-4 illustrates the relationship between soil texture and

soil moisture content.Size and total volume of pore space are a function of soiltexture and structure. Both available and unavailable water increases as claycontent increases. Thus, sands have a a much lower waterholding capacity than clay soils.Soil water holding capacity is important for irrigationamounts and frequency. Table 5-5 lists numerical values ofwater storage capacities for six common soil textures.

Remember, most garden and landscape soils have been

modified, so the values in this table may vary significantly.

Fertilizer or Food?Fertilizers contain plant nutrients. Fertilizers are not plant food.Plants produce their own food usingwater, carbon dioxide, and energy

fromthe sun to produce sugars andcarbohydrates, which, combined

withplant nutrients, do produce proteins,amino acids, enzymes, and vitamins,

asthe building blocks essential for

plantgrowth and development.

Plant Nutrients Plants need 16 elements for plant growth.

These arecalled the essential elements.

Carbon, C from carbon dioxide; Hydrogen, H from

water and Oxygen, O from water and the air, as O2.

These are the non-mineral nutrients.

There are 13 other elements (nutrients) that aregrouped into three categories:

Major nutrientsSecondary nutrientsMicronutrients

The Major Nutrients

Nitrogen, NPhosphorus, PPotassium, K

Plants require these in larger quantities;

Most likely to be deficient.These are the three elements on afertilizer label. ( N – P2O5 – K2O)

NitrogenDark green color of leaves; usually responsible

more forincreasing plant growth than any other element.Proteins & DNA/RNA

Excess- succulent growth, weak spindly plants, few fruit

Deficiency- yellowing of the leaves, reduced growth

Plants can absorb their N in the form of ammonium or

nitrates, with nitrates being the largest quantity.

Mobile in the plant; nitrates may leach in sandy soil.

Phosphorus

No other nutrient can be substituted for it. Contained in

proteins and amino acids. Without it, plants could not

convert solar energy to chemical energy for synthesis of

sugars, starches and proteins.

Excess- micronutrient deficiencies of Zinc and Iron

Deficiency- reduced growth, purpling in foliage or veins of some plants

Fixed by Al, Fe and Mn in acid soils; fixed by Ca in alkalinesoils. Important in root development of young plants.

Mobile in plant; doesn’t leach except in organic mixes.

Applied as a fertilizer in the phosphate form.

PotassiumInvolved in photosynthesis, sugar transport,

water and nutrient movement, protein synthesis, and starchformation. Improves tolerance to disease, water

stress,winter hardiness and uptake efficiency of othernutrients.

Excess- causes N deficiency and may affect uptake of

other positively charged nutrient elements.

Deficiency- marginal burn or scorch affecting photosynthetic activity. Short

internodes, weak stalks.

Involved in photosynthesis, plant-water relations,disease tolerance, and quality in fruits and

vegetables.Mobile in the plant/leaches in the soil

The Secondary NutrientsCalcium, CaMagnesium, MgSulfur, S

These are not any less essential than the major

nutrients, only being used in a smaller quantity.

Lime, if needed to raise soil pH, will supply

Calcium and/or Magnesium. Calcitic orDolomitic lime; there are other liming

materials(Hydrated lime and Quick lime ; Pelletized

lime)Gypsum is not a liming material, not

effect pH.Gypsum (Calcium sulfate) contains Ca and

S.

CalciumImportant in the structure of the plant cell walls.Stimulates root and terminal bud development.

Excess- interferes with Mg absorption; replaces K, Na

and NH4+ on soil complex; causes high soil pH-

micro’s

Deficiency- inhibition of bud and root tip growth,blossom-end rot on vegetables

Important in pH control by reducing acidity. Limited

mobility in the plant; moderately leachable.

MagnesiumCentral element of the chlorophyll molecule, so

it’sactively involved in photosynthesis, energy

metabolism,and is required for protein formation.

Excess: interferes with Ca uptake

Deficiency: reduced growth, marginal chlorosis, interveinal chlorosis starting at leaf

tips at lower to mid-plant.

Leaches from soils, is mobile in the plant. Foliage plants

susceptible. Epsom salts or Dolomitic lime, if pH is low.

SulfurComponent of some amino acids that are

importantin building proteins.

Excess: over-application of S to lower soil pH

Deficiency: symptoms are general yellowing of

younger leaves or the entire plant

High N rates may induce S deficiency. Is not mobile

in the plant, but sulfate-S is leachable in the soil.

The Micronutrients

Boron, B; Copper, Cu; Manganese, Mn ; Zinc, Zn; Iron,

Fe; Molybdenum, Mo and Chlorine, Cl

Micro meaning small; at one time called minornutrients, but not of minor importance. Soilavailability depends on pH with deficiencies

likelyabove a soil pH of 6.8

Many micronutrients are enzyme activators. Used in

smaller quantities than major or secondary nutrients.

IronImportant in chlorophyll and protein formation,

enzymesystems, respiration, photosynthesis and energytransfer.

Deficiency: interveinal chlorosis on younger tissue that

may change from yellowish to white.

Conditions for deficiency include soils high in Ca, poorly

drained soil, high soil pH, high soil P, Cu or Zn.

Acid loving plants: azaleas, blueberries, camellias,

roses, etc. need iron and will show symptoms.

Can be corrected with chelated forms of iron and other

type fertilizers containing iron , as well as amendments

that lower soil acidity; Aluminum sulfate & sulfur.Caution!

Iron deficiency- Crepe myrtle

Iron deficiency- Elm

Hydrangea- Iron deficiency

Soil pHThe term pH defines the relative acidity or

alkalinity of a substance.

The pH scale ranges from “ 0 ” to “ 14 ” , with a pH of

“ 7 ” being neutral.

0 ------------------------7-----------------------14 Acid Alkaline

pH is defined as the negative logarithm of the hydrogen

(H+) concentration.

pH - Hydrogen Ion ActivitySoil pH is expressed in logarithmic terms, not a

linearscale! Each pH unit change means a tenfold

changein acidity or alkalinity. Ex: pH 4 is 10 times as

acidic aspH 5

Older literature spoke of a soil being sour (acid) or

sweet ( basic or alkaline)

pH is one of the most important soil chemical reactions

Soil pH has a profound effect on availability of

nutrients and microbial activity. (Refer to page 5-11)

I

II

Don’t lime to this level Never happen

Need to lime

Need to lime

Need to lime

Adjusting Soil pHBase it on a Soil Test!!!! Lime or Sulfur

requirement.

Lime raises the soil pH; Sulfur reduces soil pH, more

acid. The old adage “ if a little is good, more is better”

willget you in a bind if you over-apply either of thesematerials.

Raise pH – Ag Lime, Dolomitic lime, Hydrated lime

(caution)

Lower pH- Elemental sulfur, Aluminum sulfate (caution)

Soil TestingPurpose - supply clients with enough

information tomake a wise choice regarding applications of

soil amendments and fertilizers.

Measures the plant-available portion of soil nutrients.

Soil test results form the basis for nutrientrecommendations.

Routine soil test from the LSU AgCenter Soil Testing

and Plant Analysis Laboratory costs $10, provides a soil

texture, soil pH, Calcium, Magnesium, Phosphorus,

Potassium, Sodium, Zinc, Copper, and Sulfur plus a lime

or sulfur requirement, if needed, to adjust pH for the

crop (s) listed.

No Reliable Soil Test For Nitrogen Availability* In all soils there is considerable intake

and outgo of nitrogen in the course of a

year. This is accomplished by many complex transformations. * The Nitrogen cycle is an interlocking succession of largely biochemical

reactions.* Total N encompasses all phases of N, but

available N is like a snapshot of something in

motion.

Philosophy of Soil Test Fertilizer Recommendations1. Base them on soil test results, every 3

years

2. Recommend that lower testing soils be built up to higher test levels by adding fertilizer

3. Apply maintenance amounts of plant nutrients to higher testing soils to keep them there and keep productivity high (Vegetables and high value crops)

4. Do not apply specific nutrients to soils testing very high in these nutrients

Using the Soil Test Results

Need to understand the information on the

Soil Test Results Sheet that is mailed toyou from the Soil Lab with Soil Test

Results.

*Soil Test Results and ratings (interpretations)

*Fertilizer and lime recommendations*Fertilizer management practices or

concerns (Soil Test Information Sheet)

Soil Area

*Soils are classified into two areas, upland &

alluvial. Upland soils are those in the Coastal Plains (hill soils) and the

Loessial, silt loam-textured soils, like the Macon Ridge or the Grand Coteau Ridge.

*The alluvial soils are those in the river bottoms, not creek bottoms.

Soil pH ( Soil Reaction)*Soil pH indicates the level of active

acidity.*Maintaining a soil pH between 5.7 to 6.5

will generally provide a favorable

environment for growth and development of many

plants.*Lime recommendations are made to

correct problems with soil acidity; H, Mn &Al*Recommendations are based on the soil

pH, soil texture and the crop to be grown.*Two types of lime: Calcitic or Dolomitic*Look at soil test Ca and/or Mg levels.

Soil Test Ratings

Soil testing labs use some form of rating scale within which

soil test values are placed. What do these ratings mean?

An example of this :

Very Low < 50% crop potential, with no fertilizerLow 50-75% crop potential, if not fertilizedMedium 75- perhaps 95% of the crop potentialHigh no fertilizer is needed, soil can supply allVery High no fertilizer is needed, just more cost;

potential for environmental issues

Phosphorus- P*In LA, P is extracted using the Mehlich III soil testing extractant. *Test results given as ppm of Extractable

P, a measure of the relative availability of

P.

*Not a measure of total phosphorus.

*Recommendations as lbs. of Phosphate/Ac

( P2O5 ); oz./bush; oz or lb./100 or 1,000 sq. ft., based on the crop.

Calcium, Magnesium,Potassium, Sodium, Copper, Sulfur, Zinc* Cations are extracted by the Mehlich III

soil test extractant.* Reported as Extractable nutrients, as

ppm.

* Calcium/ Magnesium levels – type of lime

* Recommendations for K as lbs. Potash/Ac

( K2O ); oz./bush or 100 or 1,000 sq. ft.

Organic Matter*Expressed as a percentage*No rating system*Measures the resistant state of

O.M. in soilConsider this:

An acre of soil measured to a depth of six and 2/3 inches weighs about 2,000,000 pounds, meaning that 1% organic matter in the soil would weigh about 20,000 pounds. It takes about 10 pounds of organic material to decompose to 1 pound of organic matter, so it takes at least 200,000 pounds (100 tons) of organic material applied to the soil to add 1% stable organic matter under favorable conditions.

Know the Size of the Plot** 1 Acre = 43,560 square feet AND** Anything at ~ 45 lb/1,000 sq. ft. = 1

Ton/Ac

Ex: Length in feet X Width in feet = Square feetGarden is 20 ft. X 50 ft. = 1,000 sq. ft.

1,000 sq. ft. divided by 43,560 sq. ft. = 0.023 Ac and

0.023 Ac X 2000 lb Lime (1 ton) = 46 lb of lime (rounded)

Use this type equation to figure lime/sulfur rates on

small areas of less than one acre.

Additional Soil Tests- STPALSoil Organic Matter $4/sample

Micronutrient Test Zn, Fe, Mn and Cu. , $5/sample

Heavy Metal Test As, Cd, Pb, and Zn., $5/sample

Optional Soil Tests Al, B, S, Soluble salts and Extractable oil; $5 for each analysis; separate

Flood Test EC, Salts, SAR, Cl, Na, etc.; $6/sample

Soil-less Routine Ca, K, Mg, P, pH, conductivity (E.C)for potting mixes nitrates ; $10/sample

The soil tests offered are not for environmental assessment purposes.

Heavy metals should be determined by labs using EPA approved methods, which determine and report these elements as totals or

semi-total values.

The W. A. Callegari Environmental Lab will run totals.

Fertilizer

Produces results that are considered desirable; applied

to obtain some desired plant response; appliedwhenever you expect to get a desired plant

response;that’s where the ratings/interpretations come in.

Fertilizer needs should be based on soil test results ~ 3

years.

A properly taken soil sample, analyzed by a soil testing

lab will give you recommendations on the fertilizer

nutrient needs of the crop (s) you will be growing.

Fertilizer SelectionRecognize the plant response you are seeking

Contains the needed nutrient (s)

Releases the nutrients when needed

Cost effective

Safe and convenient to use

Environmentally friendly

LA Fertilizer Law

Louisiana Dept. of Agriculture and Forestry- State LawRequiring fertilizer manufacturers to guarantee the

claimedfertilizer analysis on the label on a bag of fertilizer.

Nutrient analysis is based upon a percentage of weight. The

analysis is sometimes called the “grade.”

All fertilizers are labeled with three numbers that give the percentage by weight of nitrogen, phosphate and

potash.

All fertilizers are based on 100 pounds.

Example: 8-8-8 contains 24 lb. of nutrients per 100 pounds of

fertilizer.

Common Nitrogen FertilizersFertilizer material % NitrogenAmmonium nitrate 34

Ammonium sulfate 21

Urea 45-46

Potassium nitrate 13

Calcium nitrate 15

Common Phosphate Fertilizers

Fertilizer material % P2O5

Triple superphosphate (TSP) 46

Ordinary superphosphate 20

Bone meal 22 - 30

Common Potash FertilizersFertilizer material % K2O

Muriate of potash 60

Potassium sulfate 52

Potassium nitrate 44

Sulfate of potash magnesia 21also known as K Mag

Complete/Incomplete/Balanced FertilizersComplete- contains the three major

nutrients; N, P and K Ex: 12-6-6

Incomplete- lacks one of the major nutrients

Ex: 34-0-0 ; 0-0-60 ; 18-46-0

Balanced- contains the three major nutrients,

in the same proportions Ex: 8-8-8 ; 13-13-13

Incomplete to Complete FertilizerFertilizer Analysis AmountUrea 45-0-0 100 lb

Triple superphosphate 0-46-0 100 lb

Muriate of potash 0-0-60 100 lb

Produces 45-46-60 300 lb

With a grade of ~ 15-15-20 for every 100 lb

Slow- Release Fertilizers

Slow release of nutrients at a controlled rate, with a

balance of nutrients throughout the growth cycle.

Categorized by the way the fertilizer is released:1. materials that dissolve slowly2. materials from which nitrogen is released by

microorganisms3. granular materials with membranes made of resins

or sulfur that control the rate of nutrient release

from the granules into the soil

Ex: Sulfur-coated Urea and Osmocote

Slow Release - Pros and Cons

AdvantagesFewer applicationsLow burn potentialRelease varies based on fertilizer characteristicsComparatively slow release rate

DisadvantagesUnit cost is highAvailability limitedRelease rate governed by factors other than plant need

Conventional Fertilizer – Pros and Cons

AdvantagesFast actingSome are acid-formingLow cost

DisadvantagesGreater burn potential (fertilizer salts)Solidifies in the bag when wetNitrogen leaches readily

Manures/Sewage Sludge – Pros and Cons

AdvantagesLow burn potentialRelatively slow releaseContains micronutrientsConditions the soil

DisadvantagesSalts may be a problemBulky; hard to handleOdorExpensive per pound of actual nutrientWeed seeds may be a problemHeavy metals in sewage sludge

Organic FertilizersRefers to nutrients contained in fertilizer - type

productsderived solely from the remains (or a by-product)

of aonce living organism.

Cottonseed meal, blood meal, bone meal, fish emulsion

and all manures are examples of organic fertilizers. If

sold as a fertilizer, it will have a fertilizer analysis

stated on it.

Many times sold as a soil conditioner, without aguaranteed fertilizer analysis. Some have

fertilizeradded to them.Depend on soil organisms to break them down.

Manure is a Complete FertilizerLow in the amount of nutrients it can supply.

Varies in nutrient content according to the animal

source, what the animal has been eating and storage

method.

Manures are best used as soil conditioners.

Fresh manure should not be used in contact with tender

plant roots.

Application rates may vary from a moderate 70 lbs/1,000 sq. ft. to as much as 1 ton/1,000 sq. ft.

“Weed and Feed”CAUTION IS ADVISED!!!!

We use them for convenience and reduced labor.However, a big concern is that the herbicides

used onthe lawn area will be taken up by tree and shrub

rootsand severely affect or kill what we don’t want todisturb. Different herbicides control different

weedspecies.

Need to check on which herbicides are used in the

“Weed and Feed” products. Ask your County Agent!

Keep these fertilizers away from shrubs, flower beds,

and trees.

Soluble SaltsFertilizers don’t burn or damage plants if applied

correctly.

Fertilizers are salts: nitrates, sulfates, phosphates, chlorides,

carbonates, bicarbonates, borates, etc.

Consider table salt ( Sodium chloride); we have afertilizer material, Muriate of potash (Potassium

chloride.)

Fertilizer applied to the soil dissolves in the soil moisture

and diffuses out into the soil. Tender roots near fertilizer

have water drawn from them and the surrounding soil; roots

begin to dehydrate and collapse if the salt concentration is

too high, roots “burn” and plants may die or suffer severe

damage.

Salt ProblemsContainers- salts accumulate on top of the soil; white crust

or ring of deposits at soil line or the drain hole. Clay pots- inside and/or outside of the pot.

Fertilizer applied repeatedly without sufficient water to leach or wash accumulated salts through the soil.

Container plants should be leached every 2-4 months. Do this

prior to fertilizing the plant, with an amount of water twicethe volume of the container.

Do not allow leached water to remain in contact with containers.

Problems do occur in gardens, with excess fertilization, since all

fertilizers are one type of salt or another. Fertilizer salts.

Fertilizer salts- Strawberry field

Gypsum for Sodium ProblemsGypsum is calcium sulfate, a neutral salt.

Does not increase or decrease the soil pH.

Soil areas should receive an application of gypsum to

dislodge the Na on the soil exchange sites.

Thorough watering/irrigation, will move Na somewhat

deeper into the soil (away from the active rooting zone)

or out of a pot. If it’s a clay soil, salts will not move.

Calcium is left on the soil exchange sites.

Gypsum does not improve soil tilth; does not alleviate

compaction problems, unless Na is the problem!

Fertilizer Application Methods

Broadcasting

Banding

Starter solutions

Side-dressing

Foliar feeding

Wishing you the best with your gardening adventure!

Thanks for your attention!

Are there any questions?

STPAL website

http://www.lsuagcenter.com/soiltest