FERTILE SOILS IN

TRANSYLVANIA COUNTY

BART RENNER, NORTH CAROLINA

COOPERATIVE EXTENSION SERVICE.

TODAY’S CLASS:

How can I tell when fertilizer is needed?

1. Soil basics

2. How do I take a soil sample?

3. How do I read a soil test report?

4. What type of fertilizer should I

apply?

5. How much and when?

Will fertilizer fix this

problem?

SOIL STRUCTURE

SOIL PARTICLE SIZE

http://www.selectsg.com/articles_news/differences_dirt_topsoil_loam

SOIL STRUCTURE

O -Humus (organic)

A –Topsoil

B –Subsoil

C- Regolith (parent

material)

R- Bedrock

IDEAL SOIL CHARACTERISTICS

Physical

• Holds water for plant growth• Drains well• Air for oxygen absorption

Biological

• Supports diverse population of microorganisms

Chemical

• Contains needed nutrients• Proper Ph Level

BALANCE OF AERATION AND MOISTURE

Solids

Water

Air

Solids

Water

Air

Solids

Water

Air

Ideal balance

Waterlogged soil

Compacted soil

TILTH

“The physical

condition, or

structure, of the

soil as it influences

plant growth”

•Porous- allows

good drainage.

•Permits roots to

grow

•Easy to work.

20-44% in animals

56% manure/urine

13-50% 8%

16-35%

Eriksen et al., (2002) and Williams et al., (2000)

HOW CAN I TELL WHEN

FERTILIZER IS NEEDED?

Is Fertilizer Plant Food?

• No! – plants make their

own food by

photosynthesis

What is fertilizer?

• Concentrated source of the

nutrients plants need to

produce their own food

Feed me Seymour!

HOW DO ROOTS ABSORB THE

NUTRIENTS IN FERTILIZERS?

Can roots ingest fertilizer pellets?

No – nutrients must be dissolved in water

Fertilizers need water to work

• This is why liquid fertilizers work so fast!

During drought plants cannot take up nutrients

ROOTS MUST BE

HEALTHY TO ABSORB

NUTRIENTS

Nutrient deficiencies can

be symptoms of soil and

root problems

•Must rule these out

Soil pH also affects roots

ability to take up nutrients

Iron deficiency due to high

soil pH

HOW PH AFFECTS

NUTRIENT

AVAILABILITY

•Width of horizontal bars represent how available nutrient is at different pH levels

•5.5 to 6.5 ideal for most plants

•Lime raises pH

•Difficult to lower pH –sulfur temporary, choose tolerant plants

3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0

Ideal for most plants

WHAT DOES LIME DO?Raises the soil pH

NC soils slightly acidic

AZALEA WITH ROOT ROT DISEASE

– FERTILIZER WILL NOT FIX!

HOW CAN I TELL WHEN

FERTILIZER IS NEEDED?

Leaf symptoms

Lower leaves yellow and dropping = nitrogen deficiency

Lower leaves red/purple = phosphorous deficiency

Nitrogen deficiency on azalea

HOW CAN I TELL WHEN

FERTILIZER IS NEEDED?

Leaf symptoms

•Newer leaves pale,

micronutrient deficiency – most

likely iron

•Usually a pH or root health

issue

HOW CAN I TELL WHEN

FERTILIZER IS NEEDED?

Leaf symptoms

•Discoloration solid or between the veins, not in circular spots

•Distributed throughout the plant – not single branch or side

•Does not start on one side and spread to other side

POOR GROWTH?

Lack of nutrients not always the cause!

Many factors can cause poor growth – must determine what is really happening

• Root diseases or root damage

• Poor drainage

• Compacted soil

• Drought

• pH issuesWhich of our three samples do you think needs fertilizer?

Fertilizer only helps if lack of nutrients is the cause of poor growth!

• Determine through soil testing

Soil Testing = ONLY accurate way of knowing what nutrients your soil needs

Also find out pH and if changes need to be made

Do it yourself kits are extremely inaccurate!

How can I tell when

fertilizer is needed?

HOW DO I TAKE A SOIL

SAMPLE?

SOIL SAMPLING

Why do it?

Where to do it?

Why do it?

How to do it?

SOIL SAMPLING

Results are only as good as the sample!

Can be done anytime of the year

• Plan ahead: want to send samples off and get results BEFORE beginning project

Sample before any new project

Sample established areas every 2-4 years

• Every 2 years in sandy soils

• Wait 6-8 weeks after applying fertilizer or lime

HOW TO SOIL SAMPLE

Start with clean equipment

• Stainless steel soil probe, hand shovel, shovel

• Not brass, bronze or galvanized

• Clean plastic bucket

Decide where to sample

• Divide landscape into areas of unique use

AREAS OF UNIQUE USE:

SAMPLE DIFFERENT AREAS

SEPARATELY

Different plants/crops

Changes in plant health

Obvious changes in soil type (color, texture, topography)

5-10 random samples from each area, total of 1 ½ cups

HOW TO TAKE SOIL SAMPLES

Avoid thatch or mulch

Take a ‘slice’ of soil

Turf: 4” deep

Landscape beds, vegetables: 6” deep

Mix subsamples together to make one composite sample for each unique area

PACKAGING SOIL SAMPLES

•Boxes and forms available from any

Extension office

•Fill box to ‘fill’ level

•Soil can be moist but not so wet it

dissolves the box!

•Do NOT put soil in plastic bag!

•Do NOT tape box shut

Soil Test Report

• Sample ID – what you entered

• Crop 1 – what you plan to grow

Lime Recommendation

• pH level – gives number and shows where your pH is in comparison to target

range (based on soil type and what you intend to grow)

• Lime recommendation – for dolomitic or agricultural/garden lime, pounds per

1000 square feet

FERTILIZER

RECOMMENDATION

Nitrogen recommendation based totally on crop to be grown

• Standard for ornamentals and fruits/vegetables = 1lb of N per 1000 sq. ft. per year

• Multiply rate (# lbs) by Nitrogen % (first number), e.g. 7 x .15 = 1.05

• Turf recommendations = N based on type of turf

Fertilizer Recommendation

• Phosphorous and Potassium Index – between 50 and 70 is ideal, less than 50

will recommend fertilizer

• Fertilizer Recommendation – in pounds per 1000 square feet – Notice, only

Nitrogen is recommended but there is no N index

ADDITIONAL INFORMATION

• HM% - humic matter, not total organic matter

• W/V – Weight/Volume, over 1.0 usually sandy soil

• Mn, Zn, Cu, S indices – ideal range 50-70

UNDERSTANDING A SOIL REPORT

CATION EXCHANGE

CAPACITY

CEC

• Measure of soil’s capacity to hold nutrients

• Increases as organic matter, pH, and clay content increase

• Sandy soils lower, eg. 2.0

• Organic/Clay soils higher, eg. 25

Organic matter increases

CEC

WHAT SOIL SAMPLING

CAN AND CAN NOT

TELL YOU

Can

• Nutrients your soil needs

to support healthy

growth

• Soil pH, if lime is needed

or not

• If pH or nutrient levels

are contributing to plant

problems

Can Not

• Why your plant died

• If diseases are present in

the soil

• If chemical residues are in

the soil

• If your soil has depth or

compaction issues

SOIL SAMPLING IN NC

Samples are analyzed by NC Dept. of Agriculture Soil Testing Lab in Raleigh

• NOT NCSU, NOT NC Cooperative Extension

No direct cost for NC residents April -November

• Peak season fee, $4/sample Dec – March

• Pay online

Results posted online – turnaround time depends on time of year

• Jan – April: 4 to 8 weeks +

• Summer, Fall: 1 to 3 weeks

SOIL SAMPLE FORMS

Fill in contact information (ink)

• Date, County, # Samples

Make up sample ID #

• Letters or numbers

• Something you will remember (veg, flower, shrub,

etc)

Crop codes listed on back of sheet

• Lawn and garden codes will give recommendations

in lbs. per 1000 sq. ft.

HOW DO I READ A

SOIL TEST REPORT?

Available online:

http://www.ncagr.gov/agronomi/pals/

Search by last name only!

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Macronutrients

Air & Water Primary Secondary

Carbon (C) Nitrogen (N) Calcium (Ca)

Hydrogen (H) Phosphorus (P) Magnesium (Mg)

Oxygen (O) Potassium (K) Sulfur (S)

Plants need these in large quantities

Plant Nutrition:

Micronutrients

• Iron (Fe)

• Manganese (Mn)

• Copper (Cu)

• Zinc (Zn)

• Boron (B)

• Molybdenum (Mo)

• Chlorine (Cl)

Micronutrients are just as

essential as

Macronutrients,

But are needed in smaller

amounts.

All nutrients must be dissolved in

water for plants to take up!

NITROGEN 10-5-15

Promotes green, leafy growth

Most limiting nutrient

• Most common deficiency

Most forms easily leach from soil, especially sand

• Pollute surface and groundwater

Mobile in plants

• Deficiency shows up in older leaves first

• Stunted growth, yellow leaves

N

-N

Older leaves show symptoms first

NITROGEN 10-5-15

Too much burns plants

Too much increases pest problems

• Especially aphids, scale, and mealybug

Too much reduces vegetable yields

• Especially in beans, tomatoes, cucumbers, squash, peppers

N

PHOSPHOROUS 10-5-15

Promotes root growth, flower, fruit

and seed production

Held tightly by soil – leaching rare

Causes pollution when soil erodes

• P attached to soil particles

Needs to be incorporated

Frequently fertilized soils

probably have too much

• Most home gardens

P

PHOSPHOROUS 10-5-15

Mobile in plants

Deficiency

• Reduced growth

• Plants dark green

• Purple or reddish color to older leaves

Not taken up as well in cold or wet soils

• Deficiency symptoms in winter usually due to cold weather rather than lack of nutrient in soil

P

-P

POTASSIUM 10-5-15

Plant health tonic!

• Increases drought tolerance, disease resistance and improves winter hardiness

Improves flavor in melons and tomatoes

Can leach, especially in sand

• Many coastal plain soils low

Sometimes called potash

Deficiency symptoms (mobile):

• Reduced growth

• Chlorosis and burning of leaf margins – older leaves

• Necrotic spots on older leaves

K

-K

WHAT TYPE OF FERTILIZER

SHOULD I APPLY?

YOU KNOW WHAT NUTRIENTS

YOU NEED, NOW HOW ARE

YOU GOING TO APPLY THEM?

FERTILIZERS:

LOTS OF CHOICES!

Synthetic

• Manmade

• More predictable, higher analysis

• More likely to leach, burn

Natural

• Often low analysis, slow to release

• Condition the soil – feed microbes

• Expensive if only source of nutrients

• Do not release well in cold weather

FERTILIZER CHOICES

Slow Release - insoluble

• Resin or Sulfur coated or Natural

• Plants use more efficiently, available over longer time, less leaching

• Usually more expensive

Quick Release - soluble

• Dissolves rapidly

• Granular or blue crystals

• Anything plant does not use leaches

• More likely to burn, especially if high analysis, N over 10%

SLOW RELEASE FERTILIZERS

Slow release - Excellent for sandy soils unless need nutrients immediately

Coated (synthetic resin or sulfur), 0-12 month

• Osmocote and other brands

• Sulfur Coated Urea – acidifying

• Don’t apply after mid-July on trees and shrubs

Natural

• Organic or mineral

• Usually low analysis, e.g. 4-3-4

Quick-Release Fertilizers

• Supply Water-Soluble Nitrogen (WSN)

• Granular (10-10-10) and Liquid fertilizers

• Available for immediate plant uptake

• Less expensive than controlled-release

fertilizers

• May be leached from root zone - pollution

• High salt index – more likely to burn plants

and microbes!

• Often lowers soil pH

MORE FERTILIZERS

Liquid Fertilizers (blue crystals)

• Dissolve in water

• For a quick boost (fast food)

• No sustained release!

Special Purpose

• Eg. Tomato fertilizer, Camellia Fertilizer

• Marketing trick!! Often more expensive

• Acid lovers – contain Ammonium N and sulfur

• With micronutrients – what about pH?

Spikes and Pellets

• Hard for roots to access and absorb

WHICH FERTILIZER?

Slow release best, especially in sandy soils

Organic fertilizers encourage beneficial microbes

Liquid fertilizers useful when need a quick boost and when setting out transplants, but not for sustained feeding

Do you always need to fertilize?

If your plants look

healthy and are growing

at a good rate you do not

need to fertilize

WHEN SHOULD I FERTILIZE?

When plants are growing!

If P levels low, incorporate into soil

Ornamentals (trees, shrubs, perennials)

• March

• No later than August

• Do not apply high Nitrogen at planting time

WHEN TO FERTILIZE

Annual flowers, container plants

• When planted, slow release

• May need second application mid

summer

• Use liquid fertilizer for a quick

boost

Lawns

• Depends on turf type

• No earlier than April, no later than

August

WHEN TO FERTILIZE

Vegetables

• At planting time, slow release

• If using granular will require reapplication (sidedressing)

• Liquid feed for a quick boost

Fruits

• Annually, usually March

HOW MUCH DO I APPLY?

If do not have soil test report or wish to use

different fertilizer, must calculate rate

Numbers on bag represent % of N-P-K in

that fertilizer (always in that order)

100 lbs of 16-4-8 = 16lbs N, 4lbs P, 8lbs K

Application rate usually based on N, to

apply 1 lb. of actual N per 1000 sq. ft.

N is first number!

HOW MUCH DO I APPLY?

To figure out how much of any fertilizer to

apply per 1000 sq. ft. to give 1 lb. of actual

N, divide first number on the bag into 100

• Eg. for 10-5-10, 100/10 = 10 lbs.

• For 20-10-15, 100/20 = 5 lbs

• For 40-0-0, 100/40 = 2.5 lbs

1 lb. of fertilizer equals

• 2 cups 10-10-10 (granular)

• 3 cups organic (eg. Plant Tone)

• 1 ¾ cup Osmocote (time release)

HOW MUCH?

Always given on a per 1000 sq. ft. basis

Must calculate size of area fertilizing

Length x Width

If less than 1000 sq. ft., reduce amount accordingly

• 500 sq. ft. – apply ½

• 100 sq. ft. – apply 1/10

• 2000 sq. ft. – requires 2x

OVER

FERTILIZATION

Burn plant roots and tissues

Pollute ground and surface waters (N&P)

Increase insect and disease problems (N)

Cause blossoms or fruits to shed (N)

Favor leaf growth over flowers (N)

LET’S TAKE A LOOK AT SOME

POPULAR FERTILIZERS

What nutrients do they contain?

Based on nutrients, what should they be good for?

Slow or Quick release? High analysis?

Advantages/Disadvantages

How much would you need to put out to apply 1 lb. of actual

N per 1000/sq.ft.?

How many cups for 100 sq. ft.

MIRACLE GROW

ALL PURPOSE PLANT

FOOD

24-8-16

Lots of N! Plenty of K!

Quick release, high analysis

Quick boost of growth

No sustained feeding

Easy to over feed

Mix according to directions

ESPOMA PLANT-TONE

5-3-3

Low analysis, some of everything, general feeding

Slow release – organic

Sustained feeding, good for microbes

Not a ‘quick fix’

20 lbs./1000 sq. ft.

60 cups! Or 6 cups per 100 sq. ft., ½ cup per shrub

SCOTT’S SOUTHERN

TURF BUILDER

•32-0-10

•Lots of N – new growth, no

P, some K

•Some of N in slow release

form

•Sustained feeding but too

much N!

•3 lb. per 1000 sq.ft. = 6 cups

TRIPLE SUPER PHOSPHATE

0-45-0

Only P

Promotes root growth, flower and fruit production

Should only apply if soil test results indicate P is low!

Best if incorporated – very slow acting when surface applied

YOUR TURN!

The average compost contains less than 1% of any one

nutrient!

• 0.5-0.5-0.5

• Would need 200 lbs. per 1000 sq. ft!!!

Poultry litter averages around 4-4-2

• Would need 25 lbs. per 1000 sq. ft. to supply 1 lb. of N

For Comparison:

SODA

Nitrate of Soda

“Bulldog Soda”

16-0-0

BONE MEAL

6-9-0

HOLLY-TONE

4-3-4

OSMOCOTE

INDOOR/OUTDOOR

3-4 MONTH RELEASE

14-14-14

19-6-12

MIRACLE GRO

TOMATO PLANT FOOD

18-18-21

WORKING WITH SOIL IS HARD,

DON’T HURT YOURSELF!

The Garden Warm up!

TRANSYLVANIA COUNTY GIS

SYSTEM CAN BE HELPFUL

Give it a try!