Soil Fertility and Plant Nutrition for Master Gardeners

1
Soil Fertility and Plant Nutrition for Master
Gardeners
Boy did that fertility course work!

• Terry E. Poole
• Extension Agent
• Frederick County

2
Soil Quality

• This is the most important factor in plant and
  crop production.
• Soils will determine which plant species yields
  the most, the time of harvest, and ultimately the
  investment a landowner must make to yield an
  acceptable economic return from management.

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Soil Profile
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Where can you find info on a your soil?

• In the County Soil Survey Map you can find out
  what kind of soil(s) you have around your home or
  farm.
• There are also tables on various land use options
  where the different soil types are outlined for
  yield potential, limitations, and environmental
  impact.

5
Factors Controlling Plant Growth

• Light
• Mechanical Support
• Heat
• Air
• Water
• Nutrients
• All except for light, involves soil

6
Major Components of Soil
50
7
Soil Terminology

• Soil texture - concerns the size of mineral
  particles, specifically the relative
  proportion of various size groups in a given
  soil.
• Soil structure - the arrangement of these
  soil particles into groups of aggregates.

8
Soil Texture

• Soil texture is separated into three soil
  separates based on particle size.
• Sand
• Silt
• Clay

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Soil Texture Pyramid
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Soil Texture

• Silt, clay - imparts a fine texture and
  slow water and air movement, also high water
  holding capacity.
• Sandy to gravelly - are referred to as
  lighter soils with lower water holding capacity.

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Soil Texture
Mg
Ca
K20
NH4

• Sandy soils are normally very well drained and
  often lack nutrients due to constant leaching
  loss.
• Mostly clay soils are at the opposite end of the
  soil spectrum. They tend to allow water to move
  through more slowly and will stay wetter longer.
  They will hold nutrients like a magnet.

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Soil Terminology

• Pore space - is that portion of the soil
  occupied by air and water.
• - sandy soils have low soil porosity, while
  silt and clay soils have high soil porosity.
• Soil compaction - compaction reduces pore
  spaces. - fine textured, wet soils are more
  easily compacted.

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Soil Terminology

• Soil depth
• - defined as that depth of soil material
  favorable for plant root penetration - deep,
  well drained soils are the best

Talk about in a hole!
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Soil Terminology

• Slope - land topography largely
  determines the amount of drainage, runoff,
  and erosion. - the steeper the land, the more
  management is required.

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Soil Terminology

• Organic matter - it consists of plant and
  animal residues in various stages of
  decay.
• - adequate levels benefit soil by
• 1) improving physical condition
• 2) increasing water infiltration
• 3) improving soil tilth
• 4) decreasing erosion losses
• 5) supplying plant nutrients
• 6) holding cation nutrients

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Soil Terminology

• pH - expression of both acidity and
  alkalinity on a scale whose values run from 0
  to 14 with 7 representing neutrality, lt7
  represents acidity, and gt7 represents
  alkalinity.
• pH has a significant impact on the availability
  of soil nutrients.
• pH 6.5 - pH objective for most plants and
  crops.

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pH Scale
I dont see any scales.
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pH Effect on Nutrient Availability
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pH Preferences by Plants
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pH Preferences by Plants
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pH Preferences by Plants
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16 Essential Elements

• Primary Nitrogen (N) Phosphorus
  (P) Potassium (K)
• Secondary Sulfur (S) Magnesium
  (Mg) Calcium (Ca)

No more nitrogen for you!
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16 Essential Elements (cont)

• Micro-nutrients Iron (Fe) Manganese
  (Mn) Boron (B) Chlorine (Cl) Zinc
  (Zn) Copper (Cu) Molybdenum (Mo)

B
Zn
Cl
Mo
Fe
Mn
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16 Essential Elements (cont)

• The final three (3) essential elements to plant
  growth come mostly from air and
  water.
• They are Carbon (C) Hydrogen
  (H) Oxygen (O)

C
H
O
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The Primary Elements

• Nitrogen It gives plants their green color,
  promotes above ground growth, and regulates
  utilization of other elements.
• Phosphorus It has favorable affect on
  - cell division - stem strength -
  crop maturation - root development -
  flowering/fruiting -disease resistance

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The Primary Elements (cont)

• Potassium (K) - It is essential for starch
  formation and translocation of sugars. It is
  also essential to the development of chlorophyll.
  K helps plants to over-winter.

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What is the nutrient content of commercial
fertilizers?

• Expressed as a percent called the guaranteed
  analysis or fertilizer grade.
• Nutrient content always appears in this order
• total nitrogen
• available phosphate (P2O5), or
  phosphoric acid
• soluble potash (K2O)

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The Fertilizer Number

• The fertilizer number refers to a ratio of N-P-K
• 5-10-5 (1-2-1 ratio) has 5 N 10 P2O5 5
  K2O 20
• The other 80 of the material is called the
  carrier. This is typically some inert material.
• 10 - 6 - 4 (2-1-1 ratio) 10 -10 -10 (1-1-1
  ratio)

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What does a fertilizer guarantee mean?
This bag contains
5
nitrogen--10 phosphate--15 potash
or

2.5 lbs. nitrogen

5 lbs. phosphate

7.5 lbs. potash
Ag-Gro-Pro 5-10-15 50 lbs.
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Why is the fertilizer ratio important?

• The fertilizer ratio determines how much P and K
  are applied at application.
• N is the constant in the ratio.
• For example Apply 1 lb of N per 1,000 ft2 on
  lawn using 10-10-10 and 5-10-5.
• 10-10-10 1 lb N, 1 lb P2O5, and 1 lb K2O
• 5-10-5 1 lb N, 2 lbs P2O5, and 1 lb K2O

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How much fertilizer is needed to meet the
recommendation?

• Remember, the fertilizer analysis is expressed as
  a percentage.
• For example, the recommendation calls for you to
  apply 1 lb of N/1,000 ft2. How much 20-10-5
  fertilizer do you need to apply to meet the
  recommendation?
• Divide .20 into 1 and you get 5. This means that
  you need to apply 5 lbs of this material per
  1,000 ft2 to get 1 lb of N.

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How much total fertilizer will I need to apply?

• Lets take a look at a simple example.
• We need to apply some K-Mart Special 23-7-7
  fertilizer to our lawn. We need to apply it at a
  rate that yields 1 lb N/1,000 ft2.
• Our lawn is about 10,000 ft2 in area. (Thats
  length x width house, etc.)
• How much K-Mart fertilizer do we need to buy?

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How much fertilizer to buy?

• How much 23-7-7 does it take to get 1 lb of N?
• .23 divided into 1 4.3 lbs.
• 10,000 ft2 divided by 1,000 (units of
  application) 10
• 4.3 lbs. x 10 43 lbs. of 23-7-7 will be needed
  to cover the entire lawn.

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Fertilizer Calculation Example

• Joe Smith Garden
• Joe has a garden that is 45 ft. wide and 50 ft.
  long.
• He wants to plant sweet corn in it.
• The recommendation comes from the county agent as
  120-60-60/acre.
• Whats he to do?

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Fertilizer Ratio and Proportion

• First lets determine the area of the garden. 50
  x 45 2,250 ft2
• Next lets determine the type of fertilizer to
  use. 120-60-60 is a 2-1-1 ratio of
  nutrients. 10-6-4 is a fertilizer with a 2-1-1
  ratio.

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Fertilizer Ratio and Proportion

• Next, how much 10-6-4 will be needed to supply
  120-60-60?
• .10 divided into 1 10 lbs.
• So, 10 lb 10-6-4 yields N .10 x 10 lbs.
  1.0 lb P2O5 .06 x 10 lbs. .6 lb K2O .04
  x 10 lbs. .4 lb

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Fertilizer Ratio and Proportion

• So, lets calculate the total 10-6-4 needed for
  120 lbs. of N.
• 10 lbs. x 120/A 1,200 lbs. 10-6-4/A
• How much P2O5 and K2O will this yield/A?
• 1,200 x .06 (P2O5) 72 lbs.
• 1,200 x .04 (K2O) 48 lbs.
• Total nutrients/A 120-72-48

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Fertilizer Ratio and Proportion

• Now lets convert the results to 1,000 ft2.
• An acre has 43,560 ft2 in it and Joes garden has
  2,250 ft2 in it. We want to put an equivalent
  amount of 10-6-4 on Joes garden as we would have
  on an acre to meet the nutrient requirements.

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Fertilizer Ratio and Proportion

• So, lets make our final calculation.
• 1200 lbs. (10-6-4) x X
  2,700,000 43,560 ft2 2,250 ft2
  43,560
• X
  62 lbs.
• Joe needs 62 lbs. of 10-6-4 to meet the nutrient
  requirements of the sweet corn in his garden.

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Common Fertilizer Components

• Urea 46 - 0 - 0
• Ammonium nitrate 34 - 0 - 0
• UAN 30 - 0 - 0
• Ammonium sulfate 21 - 0 - 0
• Diammonium phosphate 18 - 46 - 0
• Triple superphosphate 0 - 46 - 0
• Muriate of potash 0 - 0 - 60

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Determining Fertilizer Need

• Production Goal Total lb/M1 N - P - K
• soil reserve - P - K
  crop residue - N
• manure/compost - N - P - K
• ______________
• Fertilizer lb/1,000 ft2 N - P
  K
• 1- Abbreviation for 1,000 ft2

Id hate figuring fertilizer.
42
Soil Reserve
Why is my soil bad?

• Soil test - private labs
• Frequency of testing - depends on crop and
  management
• Typical test looks at P, K, Ca, Mg, O.M., and pH.
  Minors are as needed.

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Crop Residue

• Benefits left by a previous crop or cover crop.
• Previous crops leave little unless it was a
  leguminous crop.
• Leguminous crops leave nitrogen.
• The amount of N left depends on the species of
  legume and the stand density and maturity.
• Cover crops are not harvested and will recover
  nutrients otherwise lost.

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Available Organic Nitrogen Only part of the
nitrogen in organic fertilizer materials becomes
plant-available -- through the process of
mineralization -- the year its applied.
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Nitrogen Credits

• Organic nitrogen in organic sources continues to
  break down or mineralize for several years after
  application.
• The largest proportion of this organic nitrogen
  breaks down and becomes available in the year of
  application.
• Organic sources include manure, biosolids
  (sludge), and composts.

Whats that about breaking down with age?
46
The Loss of Nitrogen When Spreading Manure

• Nitrogen in the form of ammonia is volatile.
• When manure is left on the soil surface after
  application, its ammonia nitrogen can be lost
  through the process of volatilization.
• The longer it sits, the more of it
  is lost.

Wow, thisll clear your sinuses.
NH3
NH3
NH3
NH3
NH3
NH3
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Estimated Manure Values
Do I look like a chicken?

• Dairy (fresh, spread daily) 89 moist. 7 - 3
  - 6 (lb/T)
• Dairy (stored outside, leachate lost) 87 moist.
  3 - 2.5 - 4 (lb/T)
• Poultry (layer stored in pit) 65 moist. 25
  - 27 - 24 (lb/T)
• Swine (storage tank beneath slotted floor) 95
  moist. 2.5 - 3 - 5 (lb/T)
• Beef (bedded manure pack under roof) 80 moist.
  5 - 4 - 8 (lb/T)

Umm, this tastes like chicken.
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Use of Raw Manure

• Heavy applications can throw off nutrient
  balance.
• Excess available N can lead to excessive growth
  and nitrate buildup in plants.
• Plants with high nitrates do not store as well,
  become diseased, and attract insects.
• Nitrogen and phosphorus are potential pollutants.
• Weed seeds pass through animals.

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Often Forgotten Sources of N

• Carryover from past manure/biosolids
• Cover crops ( fixed recycled N)
• N released from soil organic matter
  (40-80 lb/A)
• Nitrates in rain irrigation water
• Weeds, plowed down have slow-release N, 85 lb/T
  pigweed, 80 lb/T lambsquarter
• Crop residues, humus, and composts

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Fertilizer Application Terms

• Broadcast - fertilizer is applied uniformly
  to entire field before crop emerges.
• Topdress - fertilizer is applied uniformly
  to entire field after crop emerges.
• Plowed down or tilled in - fertilizer is
  applied to field then is tilled in with a disk
  or a plow.

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Fertilizer Application Terms

• Banded - fertilizer is applied directly
  over the top of the crop row, generally
  before the crop emerges, omitting the area
  between the rows.
• Side-dressed - fertilizer is applied
  directly to growing crop, generally in a band
  at the base of the plant.

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Spreader Calibration

• Calibration is a way to set your fertilizer
  spreader to apply material uniformly at the
  desired rate.
• It insures application of the required amount of
  nutrients without over-fertilizing.
• Two common methods are used - weight-area
  method - load-area method

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Basics of Calibration
Area Length x Width
L e n g t h
L e n g t h
Width
Width
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Dont Overload!
Idiots!
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How to Calibrate a Spreader

• Measure the actual rate of application.
• Compare actual application rate to the
  recommended application rate.
• If the application rate is substantially greater
  or less than the recommended rate, try -
  changing equipment settings

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Load-Area Method

• Know
• capacity of the spreader
• size of the area where fertilizer is to be
  applied
• Apply fertilizer, then measure the amount of
  material it takes to refill the spreader.
  Project rate of application to proper units (A or
  1,000 ft2).

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Weight-Area Method

• 1. Arrange at least 3 plastic sheets in the
  center of the spreaders path.
• 2. Drive the spreader over the center of the
  sheets at a specific setting.
• 3. Collect weigh the material on each sheet.
• 4. Average the quantity applied to the sheets and
  project to lbs./A or lbs./1000 ft2.

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Basics of CalibrationUsing Sheets and Pans
1
2
3
Spread manure
9
7
2
1
5
Spread manure
8
3
4
6
10
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Weight-Area Method

• Simple Example
• Calibrate typical 24 inch drop spreader using
  10-6-4 fertilizer.
• Make a tray to capture fertilizer material to be
  dropped.
• Measure distance of 50 ft. This works out to 2
  ft. x 50 ft. 100 ft2, which is 1/10 of 1,000
  ft2.
• Operate the spreader over this course until you
  collect 1 lb. of material, which is 1/10 of the
  10 lbs. needed to applied over the 1,000 ft. area.

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Lets take a quick look at some other materials
we apply to our soils.
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Limestone

• Supplies calcium and magnesium
• Mined calcium carbonate is the principle liming
  material, typically 50 oxides
• CaCO3 equivalent is the basis for liming material
  recommendation rates
• Comes in various forms and grades

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Limestone

• Mesh size determines how quickly it reacts in the
  soil.
• Good quality ag lime is typically 80 90-100
  mesh and 20 40 mesh.
• Ground dolomite (dolomitic lime) is over 10
  magnesium it is a good source of Mg when needed.

Ca
Ca
H
H
Ca
Ca
Clay Particle (-)
Ca
H
H
H
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Liming Notes

• Limestone recommendations are based on raising
  the pH of the plow layer (top 7-9) to 6.5
  except for special crops.
• Limited to 35 lb/1,000 ft2 oxides/year when not
  incorporating i.e. lawns.
• Avoid applying liming products and fertilizer at,
  or around the same time.
• Liming materials laying on the surface will
  neutralize pesticides.

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CompostDecomposed Plant animal Matter

• When correctly done
• - pH is near neutral
• - CN ratio is 151
• - Majority of weed seeds
  disease organisms are dead.
• - Offers a well balanced slow release supply of
  nutrients.
• - As much as 1/4 of compost weight is microbes
  (dead alive).

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Principles of Composting

• Best composts come from piles with the highest
  microbial activity.
• Temperature is easiest sign of microbial
  activity.
• Good composts heat to approximately 140 - 1600 F
  within the first 3 or 4 days.

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Principles of Composting

• Small particle size makes a greater surface area
  available to microbes. - particles that are too
  small however can pack a pile.
• Adequate volume, or size of pile keeps it from
  cooling too quickly. - piles 4 x 4 x 4 ft. do
  well.

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Unfinished Composts
OOPS!

• Can hurt crops
• Chemicals formed in process are toxic to plants.
• N can be tied up.
• Good composts take 12 - 18 months
• Moisture must be adequate (50 - 70) similar to a
  squeezed sponge.
• CN ratio in initial pile should be 301

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Common CN Ratios

• Undisturbed top soil 101
• Alfalfa 131
• Rotted barnyard manure 201
• Corn stalks 601
• Small grain straw 801
• Oak 2001
• Spruce 10001

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Compost Problem Solving

• Bad Odor - not enough air
  - turn the pile more frequently
• Center of pile too dry - not enough
  water - moisten while turning

Boy, this stinks!
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Compost Problem Solving

• Pile is damp warm in center, but nowhere
  else. - pile is too small - collect
  more material and mix the old ingredients into
  a new pile
• Pile is damp sweet smelling will not heat
  up. - lack of nitrogen - mix in N-rich
  material like fresh grass, manure,
  or urea

71
Crop Rotation and Cover Crops

• Benefits crop fertility - fixed and
  recaptured nutrients
• Benefits soil structure (tilth) - cover crops
  add organic matter - variability in root growth
  improves soil pores and water penetration
• Pest management - breaks the parasite life
  cycle
• Harvest vs. cover crop is the decision

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What is a Cover Crop?

• A crop whose main purpose is to benefit the soil
  or other crops in one or more ways, but is not
  intended to be harvested for feed or sale.

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Benefits of Cover Crops

• Cuts fertilizer bill - fixed nitrogen -
  recycles nutrients
• Reduces soil erosion
• Reduces water pollution
• Improves soil tilth - physical properties of
  soil favorable to plant growth

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Benefits of Cover Crops

• Cuts herbicide costs - mulch -
  alleopathy
• Reduces insect pests
• Reduces disease organisms and nematodes
• Provides wildlife forage and habitat

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N Furnished by Cover Crops

• alfalfa, alone 80 lb alfalfa/grass 60 lb
• ladino clover 80 lb crimson clover 80 lb
• red clover, alone 80 lb red clover/grass 40
  lb
• common vetch 50 lb lespedeza 30 lb
• hairy vetch 100 lb winter peas 90
  lb
• cowpeas 40 lb soybeans 35 lb
• mostly grass 0 lb

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Legume Inoculation

• Legumes fix nitrogen (N) in
  a symbiotic relationship (root nodules) with
  Rhizobium sp. bacteria.
• Infection takes place at seed germination so high
  populations of the proper bacterium are necessary
  for adequate nodulation.

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Root Nodules on Clover
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Alfalfa Inoculation Study

• ?Good Inoculation?
• No nodulation

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Proper Inoculation

• Always inoculate legume seed, or use
  pre-inoculated seed.
• Check expiration date on seed, or inoculant
  package.
• Use correct inoculant specific to the legume you
  are inoculating.
• Store inoculum and inoculated seed in a cool, dry
  place. Inoculum is a living organism.
• Low pH and heavy N use reduce nodulation

80
Disadvantages of Cover Crops

• Can be expensive to establish.
• Can be difficult to eliminate.
• Can become a weed.
• Can compete with your crop.
• Not a cash crop lose income from crop. -
  benefits are more indirect
• Some cover crops are more flexible than others
  with seeding times.

81
Thanks for your enthusiastic attention.
That worm is toast!
Pooles Farm Organic Carrots
POOLES FARM