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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!
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
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
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.
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
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)
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