Soils class for Transylvania Master Gardeners

1. Soils and composting for the
Master Gardener
Bart Renner, North Carolina
Cooperative Extension
March 31, 2020

2. Soil Structure

3. Soil Particle size
http://www.selectsg.com/articles_news/differences_dirt_topsoil_loam

4. Soil Structure
• O -Humus (organic)
• A –Topsoil
• B –Subsoil
• C- Regolith (parent
material)
• R- Bedrock

5. Ideal Soil Characteristics
• Physical
– Holds water for plant growth
– Drains well
– Air for oxygen absorption
• Chemical
– Contains needed nutrients
– Proper Ph Level
• Biological
– Supports diverse population of microorganisms

6. The Soil Ecosystem???
• A Microherder’s Manifesto- Molly Haviland

7. Balance of Aeration and Moisture
Solids
Water
Air
Solids
Water
Air
Solids
Water
Air
Ideal balance
Waterlogged soil
Compacted soil

8. 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.

9. So what’s wrong with
my plant?
• Biotic or abiotic ?

10. 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!

11. 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

12. 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

13. What does lime do?
• Raises the soil pH
• NC soils slightly acidic

14. 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

15. Azalea with root rot disease – fertilizer
will not fix!

16. 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

17. 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

18. 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

19. • 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?

20. Soil Sampling
• Why do it?
• Where to do it?
• Why do it?
• How to do it?

21. 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

22. 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

23. 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

24. 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

25. 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

27. Soil Test Report
• Sample ID – what you entered
• Crop 1 – what you plan to grow

28. 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

29. 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

30. 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

31. 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

32. Understanding a Soil Report

33. Use technology to help with Math!
• Our friends in Georgia have done the hard work

34. Working with soil is hard, don’t hurt
yourself!
• The Garden Warm up!