1. Making Your Garden Green and Healthy

2. The Perfect Soil It doesn’t exist, but you can come close
Components of the perfect soil
Good texture
Good structure
Good water content
Good oxygen content
Good nutrient content
Good pH
Good management can improve most of these.

3. Soil Texture The percentage of sand, silt, clay in soil
Mineral fraction
Sand
Silt
Clay
Organic fraction
Living
Dead

4. Texture, Water and Nutrients
Water Holding capacity
CEC
Clay content Sand content
Clay content Sand content
Infiltration capacity
Clay content Sand content

5. Texture, Water and Nutrients
Soil colloids: a portion of the mineral and organic fractions
Clay
Humus K+
Fe2+
Zn2+
H2O
H2PO4-
H2O
Cu2+

6. Texture and Water capacity
As discussed, clay and organic matter increase water holding
But why is clay bad and OM good?

7. Texture and Water Capacity
Understanding soil-water dynamics
Three important water contents
Saturation
Field capacity
Wilting point
Plant available water is the difference between field capacity and wilting point

8. Texture and Water Capacity
sands loams clays
Soil Texture
Plant available water
Field capacity
Wilting point
Water Volume in Soil
Effect of OM
Field capacity
with OM additions
Plant available water w/ OM
Field capacity
Wilting point
with OM additions
Water Volume in Soil
Plant available water
Wilting point
sands loams clays
Soil Texture

9. Managing Texture What is the best texture?
Loam: maximize the benefits of sand and clay, minimize the negatives
How do you minimize the effects of bad texture?
Add organic matter: the benefits of clay without the negatives
Wouldn’t recommend adding sand. Sand adds no fertility to soil, plus very, very heavy.

10. Soil Structure How soil solids are arranged together
Soil solids clump together into little aggregates called “peds”
Macropores between peds, micropores within peds
Sand does little to create structure, but the pores between sand grains are often macropores already

11. The importance of soil structure
Soil’s composition:
50% solid material
25% water
25% gas
Gas
Water
Solids

12. Good structure Strong peds with lots of macropores in between
Peds are granular or blocky
The 50% solid, 25% gas, 25% water ratio is maintained most of the time

13. Good structure How do you get it? How do you maintain it? Good texture
Can’t be managed
Good OM content
Can be managed
How do you maintain it?
Talk about how OM attracts biology that can help to create structure

14. Good Structure Maintaining structure Manage tillage carefully
Keep soil covered
Cover crops?
Avoid compaction
Incorporate OM

15. Good nutrient content Greatly dependent on management Fertilizers
Concentrated nutrient source
Conditioners
Organic matter
Management can result in direct changes. In most other management, you are conditioning the soil to be better at its functions in the future. Here, you can directly add nutrients and see quick results

16. Fertilizers
All fertilizers provide one or more plant essential nutrients
Macronutrients: Nitrogen (N), Phosphorous (P), Potassium (K), Sulfur (S), Calcium (Ca), Magnesium (Mg)
Micronutrients: Iron (Fe), Manganese (Mn), Zinc (Zn), Copper (Cu), Boron (B), Molybdenum (Mo), Nickel (Ni), Cobalt (Co), Chlorine (Cl)

17. Fertilizers N-P-K: what do they do General rule
N is for growth, especially leaves and shoots
P is for root and shoot production
K is for hardiness and durability
A lot more roles tham this. N is part of most plant proteins and chlorophyl. Phosphorous is part of ATP enzyme which creates energy, as well as DNA and RNA. K ascts as activator for many enzymes and as salt solution to increase osmotic pressure in roots

18. Soil Conditioners Many types, but have some general characteristics
OM rich
Lower nutrient concentration than fertilizer
So, why use them?
Well conditioned soil needs less fertilizer
Conditioning improves structure, water holding capacity, CEC
Feeds the soil food web
Compost can come from a compost pile, composted leaf litter from a municipality, composted manure or sewage sludge. Can make your own or can buy it commercially

19. Soil Conditioners Soil food web 1 to 4 billion bacteria per teaspoon
40 yards to 40miles of fungi roots per teaspoon

20. Soil Conditioners Soil food web
Soil biology releases nutrients from OM, from each other, and from the mineral material of soil.
There are more than enough nutrients in soil to feed all your plants without any fertilizer additions
…….it just has to be made available.

21. Good pH What is the ideal pH? How does it affect plant growth
Depends on the plant
How does it affect plant growth
It affects nutrient availability

22. Soil pH and Nutrients

23. Keys to Healthy Soil Do: Add organic matter! This will….
Feed soil biology
Power the soil food web
Increase water and nutrient holding capacity
Increase structural formation and infiltration

24. Keys to Healthy Soil Don’t Compact the soil Leave the soil bare
Overtill

25. The End!
Dan Schwartz Soil Scientist Fairfaxcounty.gov