Plant Nutrition &

Fertilizers

WMAMG 1/31/17

By Dawn Pettinelli

UConn Soil Nutrient Analysis Lab

dawn.pettinelli@uconn.edu

SOIL-PLANT SYSTEM

• Relationships between

plants & soils evolved

over billions of years.

• For plant life to endure,

needs nutrients.

• Micro-organisms evolved

with plants to break down

organic matter – symbiotic

relationships.

• Closed system.From: Extension.org

From: rmsiblog.wordpress.com

SOIL FERTILITY

Soil Fertility is defined in

terms of both soil

nutrient levels and the

ability of the plant to

recover those nutrients.

Soil conditions and

cultivation can either

favor or adversely affect

nutrient release and uptake

by the plant.

PLANT NUTRITION

• INORGANIC SIDE -

Includes inorganic elements

like Ca+2, NO3-, Fe+3, etc.

• ORGANIC SIDE –

Includes enzymes,

hormones, chelated

elements, antibiotics, and

other substances. Not as

much known but doesn’t

mean less important.

IDEAL SOIL PROVIDES

PLANT ROOTS WITH:

• Evenly distributed water

• Oxygen for root respiration

• Oxygen for microbial activity

• Good pore structure so roots can grow

freely and deeply

• Nutrient supply

SOIL pH & SCALE

Graphic by R. Zito, UConn MG 2010

Soil pH is the

measurement

of acidity or

alkalinity of

the soil

Chart showing a range of pH from 1 to 12 and the approximate pH of produces commonly used in our society every day.

From: The Nature and Properties of Soils, 11th edition by Nyle C. Brady and Ray R. Weil

WHY NEW ENGLAND’S SOILS

ARE ACIDIC

• PARENT MATERIAL IS LOW IN BASE CATIONS

• CARBON DIOXIDE (ROOT/MICROBE RESPIRATION) AND WATER PRODUCES CARBONIC ACID

• ORGANIC MATTER DECOMPOSITIONPRODUCES ORGANIC ACIDS

• ACID RAIN

A SOIL’S pH AFFECTS:

• NUTRIENT AVAILABILITY

• ELEMENT TOXICITY

• MICROBIAL ACTIVITY

• FATE OF MANY SOIL POLLUTANTS

• ROOT GROWTH

• AGGREGATE STABILITY

pH VS NUTRIENT AVAILABILITY

WIDTH OF BAR SHOWS

THE RELATIVE

AVAILABILITY OF EACH

NUTRIENT ELEMENT

WITH A CHANGE OF

SOIL pH. YELLOW AREA

OF CHART (6.0 to 7.0) IS A

GOOD RANGE FOR

MOST GARDEN PLANTS.

FROM GARDENS ALIVE CATALOG, 2000

POTATO SCAB

• CORKY SCABS OR BROWN

SUNKEN SPOTS

• POTATOES DO NOT STORE

WELL THOUGH TASTE IS

NOT AFFECTED

• SOILBORNE

• AFFECTS POTATOES,

BEETS, CARROTS,

TURNIPS, PARSNIPS

• MAINTAIN A SOIL pH OF 5.2

OR BELOW

INTERVEINAL CHLOROSIS

INTERVEINAL CHLOROSIS IN RHODODENDRON TYPICALLY CAUSED BY IRON DEFICIENCY. THIS MAY ALSO INDICATE OTHER MICRONUTRIENT DEFICIENCIES LIKE ZINC OR MANGANESE AS WELL AS DEFICIENCIES IN MACRO NUTRIENTS.

Photo by Carol Lambiase, MG

CHANGING SOIL pH

• Apply Sulfur

• Apply Acidic Salts of

Iron, Aluminum or

Ammonium

• Peat Moss

• Apply Limestones or

Hydrated Lime

• Soluble Calcium

Products

• Apply Woodashes

• Compost

To Lower pH: To Raise pH:

AMOUNT OF LIME NEEDED DEPENDS

UPON:

• NECESSARY CHANGE IN SOIL pH

• CHEMICAL COMPOSITION OF

LIMING MATERIAL

• BUFFERING CAPACITY OF SOIL

FERTILIZER EFFECTS ON

SOIL REACTION

Ammonium-N

based fertilizers

are

ACIDIC

They lower pH

Nitrate-N based

fertilizers

are

BASIC

They raise pH

The soil pH change is temporary!

ESSENTIAL ELEMENTS

C HOPKNS CaFe Mg B Mn

CuZn Mo and Cl NiCo

MACRONUTRIENTS - GROUP I

SUPPLIED BY AIR AND

WATER:

CARBON

HYDROGEN

OXYGEN

ARE THE BUILDING

BLOCKS OF PLANT

LIFE

CO2 + H20 = C6H12O6 + O2Illustration from Botany for Gardeners by Brian Capon, 1990

MACRONUTRIENTS - GROUP II

• NITROGEN

• PHOSPHORUS

• POTASSIUMTHESE THREE ELEMENTS

OCCUR NATURALLY IN THE

SOIL BUT OFTEN IN

LIMITED AMOUNTS. WE

COMMONLY ADD THESE

NUTRIENTS BY FERTILIZING.

MACRONUTRIENTS - GROUP III

• CALCIUM

• MAGNESIUM

• SULFUR

THEY OCCUR IN SOILS

NATURALLY BUT IN

VARYING AMOUNTS. WE

SUPPLY Ca AND Mg WITH

LIMESTONE OR OTHER

AMENDMENTS LIKE

SUPERPHOSPHATE. S IS

USUALLY SUPPLIED BY

ACID RAIN IN OUR PART

OF THE COUNTRY.

MICRONUTRIENTS - GROUP IV

• BORON

• COPPER

• IRON

• MANGANESE

• MOLYBDENUM

• ZINC

• CHLORINE

POSSIBLY Si, Co, Ni

Micronutrients or trace elements are needed in very small amounts, ie. an acre of corn only uses 1/2 ounce boron!!!!

Naturally supplied by soil but pH affects availability.

Often added to synthetic fertilizers, generally present in natural organic fertilizers

HEAVY METALS - 5

METALLIC IONS THAT TO A GREATER

OR LESSER DEGREE ARE TOXIC TO

HUMANS AND OTHER ANIMALS. SOME

ARE REQUIRED BY PLANTS IN TINY

AMOUNTS. THEY INCLUDE ARSENIC,

CADMIUM, CHROMIUM, COPPER, LEAD,

MERCURY, NICKEL AND ZINC

HOW NUTRIENTS BECOME

AVAILABLE

• Weathering of Minerals

• Soil Chemical Reactions Dissolve Larger

Compounds

• Rain Carries Nutrients From Atmosphere

• Microbial Decomposition of Organic Matter

• Fertilizer/Limestone Application

HOW NUTRIENTS TAKEN UP

• ROOT INTERCEPTION - Absorbed

from soil solution at root surfaces

• MASS FLOW - As plants transpire, water is

lost through leaves and then replaced

through roots

• DIFFUSION - Nutrients move from areas of

greater to lesser concentrations

Plant Growth Vs. Nutrient Concentration

Graphics by R. Zito, MG 2010

FACTORS CONTROLLING

NUTRIENT SUPPLY AND UPTAKE

• Soil Moisture

• Soil Air

• Soil pH

• Soil Organisms

• Soil Compaction

• Soil Temperatures

• Nutrient Interactions

• Amount of Organic Matter

NITROGEN

• PART OF ALL LIVING CELLS

• STIMULATES GREEN LEAFY GROWTH

• PLANTS TAKE UP MOSTLY AS NO3 AND

SOMETIMES NH4

• DEFICIENCY SYMPTOMS INCLUDE

SMALL LEAVES, YELLOWING OR

SHORT, THIN GROWTH

NITROGEN CYCLE

PHOSPHORUS

• NECESSARY FOR PHOTOSYNTHESIS, FLOWERING, FRUITING AND MATURATION

• ENCOURAGES ROOT GROWTH

• COMPONENT OF DNA

• DEFICIENT PLANTS MAY BE STUNTED OR SPINDLY, DARK GREEN, PURPLISH OR YELLOW COLOR

PHOSPHORUS

EFFICIENCY VS pH

0

10

20

30

40

50

60

70

80

90

100

pH 5.0 pH 6.0 Ph 6.5-7.0

Relative Efficiency

POTASSIUM

• REMAINS IN IONIC FORM IN PLANT CELL, ACTS AS AN ACTIVATOR FOR CELLULAR ENZYMES

• HELPS REDUCE WATER LOSS FROM STOMATES AND INCREASES ROOT CELLS’ ABILITY TO TAKE UP WATER

• HELPS PLANTS ADAPT TO ENVIRONMENTAL STRESS

• IMPROVES FLAVOR, COLOR AND STEM STRENGTH

AVAILABILITY OF

NUTRIENTS REDUCED BY:

• REMOVAL OF

BIOMASS

(HARVEST AND

WEEDING)

• LEACHING

• PRECIPITATION

INTO INSOLUBLE

COMPOUNDS

SOIL TESTING

Consider your soil a storehouse for plant nutrients, a pantry of sorts. A soil test is a means to take a chemical inventory of the available nutrients in your soil. Can tell if you need more nutrients or if the shelves are overstocked.

WHICH ONE TO CHOOSE?

Graphic by R. Zito, MG 2010

FERTILIZERS AND

AMENDMENTS

• A FERTILIZER is any material added to soil in order to supply plant nutrients. Comes with a guaranteed analysis.

• An AMENDMENT improves aeration, drainage, structure, fertility and the ability of the soil to hold water and nutrients (and it may or may not supply nutrients)

FERTILIZER GRADESTHE 3 NUMBERS ON THE

FRONT OF THE LABEL ARE

REFERRED TO AS THE

GRADE OR GUARANTEED

ANALYSIS. THEY STAND

FOR THE MINIMAL

AMOUNTS OF TOTAL

NITROGEN (N),

AVAILABLE PHOSPHATE

(P2O5) AND WATER

SOLUBLE POTASH (K2O)

BY PERCENT DRY WEIGHT

FERTILIZER RATIOS

GRADE

• 20-20-20

• 5-10-5

• 13-24-12

• 12-4-8

• 20-4-8

• 0-45-0

RATIO

• 1:1:1

• 1:2:1

• 1:2:1

• 3:1:2

• 5:1:2

• 0:1:0

GUARANTEED ANALYSISTHIS FERTILIZER

CONTAINS ALL WATER

SOLUBLE

NITROGEN(WSN). IT

ALSO CONTAINS

MAGNESIUM, SULFUR,

IRON AND

MANGANESE. ALL

THESE NUTRIENTS ARE

FROM INORGANIC

SOURCES.

BEST FERTILIZER TO USE

DEPENDS ON:

• NUTRIENTS NEEDED

• SOIL TEXTURE

• AMOUNT OF SOIL ORGANIC MATTER

• METHODS OF APPLYING

FERTILIZER

• YOUR TIME AND EFFORTS

TYPES OF FERTILIZERS

• NATURAL/ORGANIC includes fertilizers

derived from the remains or a by-product of a

plant or animal (manures, composts, seaweed,

bonemeal) as well as untreated mined

materials (rock minerals)

• SYNTHETIC FERTILIZERS are materials

that have been chemically altered,

manufactured and/or synthesized.

COMPARISON OF FERTILIZERSCONVENTIONAL FERTILIZERS

ADVANTAGES

• FAST ACTING

• LOW COST

• HIGHER NUTRIENT CONTENT SO LESS IS NEEDED

• SOME ARE ACID-FORMING

DISADVANTAGES

• GREATER BURN POTENTIAL

• MAY REQUIRE MORE FREQUENT APPLICATIONS

• NUTRIENTS READILY LEACH

• ENERGY USED FOR PRODUCTION

NATURAL/ORGANIC FERTILIZERS

ADVANTAGES

• LOW BURN POTENTIAL

• RELATIVELY SLOW RELEASE

• CONTAINS MICRONUTRIENTS

• IMPROVES SOIL CONDITIONS

• ENCOURAGES SOIL ORGANISMS

• INCREASES ORGANIC MATTER

DISADVANTAGES

• EXPENSIVE PER LB NUTRIENT

• BULKY

• ODOR

• SLOW NUTRIENT RELEASE

• WEED SEEDS/HEAVY METALS

HARVESTING ROCK MINERALS

“NEARLY 90 YEARS OF

MINING HAVE

TURNED 80% OF

NAURU INTO A LUNAR

LANDSCAPE OF BARE

CORAL

PINNACLES”NATIONAL GEOGRAPHIC

MINING FOR

PHOSPHATE, A RICH

FERTILIZER BASE

FORMS OF FERTILIZER

• WATER SOLUBLE

POWDERS

• SLOW RELEASE

PELLETS

• LIQUIDS

• GRANULAR

SOLIDS

• SPIKES/TABLETS

• PLANT/ANIMAL

MEALS

SPECIALTY FERTILIZERS

• GARDEN FERTILIZER 5-10-5

• ROSE FOOD 5-9-6

• FLOWER FOOD 7-7-7

• AZALEA AND EVERGREEN

FOOD 10-4-6

• TOMATO FOOD 5-10-10

• BULB FOOD 3-10-6

• CITRUS FOOD 12-6-8

• PALM FOOD 10-6-6

GROWTH ENHANCING

SUBSTANCES

• CHELATING

AGENTS

• ENZYMES

• HUMIC ACID

• PLANT HORMONES

APPLICATION METHODS

• BROADCASTING

• BANDING

• STARTER SOLUTIONS

• FOLIAR FEEDING

• FERTILIZER SPIKES OR STAKES

• LIQUID SOIL INJECTION

• DRILL OR PUNCH BAR HOLES IN SOIL

• LIQUID SURFACE APPLICATION

TIMING OF FERTILIZER APPLICATIONS

• INFLUENCED BY TYPE OF CROP

• MOST LANDSCAPE PLANTS AND

PERENNIALS FERTILIZED IN SPRING

• BULBS FERTILIZED IN FALL

• FERTILIZE LAWNS SPRING AND FALL

• INCORPORATE FERTILIZER INTO ANNUAL AND

VEGETABLE BEDS BEFORE PLANTING, SIDEDRESS

IF NECESSARY

• USE A 6 MONTH SLOW RELEASE FOR CONTAINERS

OR A WATER SOLUBLE AS DIRECTED (USUALLY

EVERY 7 TO 10 DAYS)