Soil Management for the Home Gardener

Dr. Greg SchwabExtension Soil Management Specialist

Estill County Horticulture SeminarFebruary 3, 2004

Soil Management for the Home Gardener

Dr. Greg SchwabExtension Soil Management Specialist

Estill County Horticulture SeminarFebruary 3, 2004

Idealized Kentucky Soil Idealized Kentucky Soil

Pore Space 50%

Soil Minerals(Silt loam)

47%

Organic Matter 3%

Macropores• Include earthworm channels

• Old root channels

• Surface Cracks

Controls soil permeability and aerationControls soil permeability and aeration

Beach sand is almost entirely Beach sand is almost entirely macropores – infiltration is very high, macropores – infiltration is very high, but water holding capacity is very lowbut water holding capacity is very low

Micropores• Very fine pores

• Similar to pores in a sponge or towel

• Hold water against the force of gravity

Much of the water held in micropores Much of the water held in micropores is available to plants, is available to plants, but some is but some is held so tightly that plant roots cannot held so tightly that plant roots cannot use it.use it.

Idealized Kentucky Soil Idealized Kentucky Soil

Macropores 25% Soil Minerals

(Silt loam)47%

Miropores 25%

Organic Matter 3%

Disturbed/Compacted KY Soil Disturbed/Compacted KY Soil

Air5%

Soil Minerals(Silt loam)

72%

Water 20%

Organic Matter 3%

Characteristics of soil with poor internal structure

• Slow permeability

• Very wet natured

• Crust easily

• Poor plant productivity

Once lost, soil structure is very hard Once lost, soil structure is very hard to rebuildto rebuild – – prevention is the keyprevention is the key

Gray Soil = No Oxygen = No Root GrowthGray Soil = No Oxygen = No Root Growth

Maintaining Soil Structure

• Prevent soil compaction

8 10 12 14 16 18 20 228 10 12 14 16 18 20 22

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Soil Moisture Content (%)Soil Moisture Content (%)

Optimum M.C.=14.3% for a silt loam

Higher Higher Yield Yield Potential?Potential?

Maintaining Soil Structure

• Use roto tiller sparingly

Compaction caused by tillageCompaction caused by tillage

4 – 8”4 – 8”

0.5 – 2”0.5 – 2”

Inaccessible water and nutrients

Slide by: R. PearceSlide by: R. Pearce

Use mulch to control weeds Use mulch to control weeds and conserve moistureand conserve moisture

Incorporate Compost or Organic Incorporate Compost or Organic Material when TillingMaterial when Tilling

• Don’t exceed 10% per year

–½ inch mixed into the surface 5 inches

• Stabilized compost is much better

–Fresh manure use very sparingly

–Uncomposted leaves or straw tie up soil nitrogen

• Wood ash is a good sources of nutrients, but doesn’t contain organic matter

Use Cover Crops Use Cover Crops • Turnips and mustard greens

–Grow very good in the fall

–Provide ground cover to prevent erosion

–Have strong tap roots to break compaction and provide future root channels for better infiltration

• Wheat

–Roots provide organic matter

–Improves soil structure

–Reduces winter annual weed pressure

Soil MineralsSoil Minerals

Macropores 25% Soil Minerals

(Silt loam)47%

Miropores 25%

Organic Matter 3%

Soil Mineral Phase Soil Mineral Phase • Sand

–Large soil particles – feel gritty and can be seen with the naked eye

• Silt

–Much smaller than sand – feel smooth about the size of flour particles

• Clay

–So small particles can only be seen under a microscope

–Chemically active part of the soil

Cation Exchange Capacity Cation Exchange Capacity

CaCa++++

Plant Root

HH++

KK++HH++

KK++

-----

- - --

-

-

-

- - -

-

HH++NHNH44++CaCa++++

CaCa++++

HH++

HH++

KK++

KK++

MgMg++++

MgMg++++

CaCa++++

CaCa++++CaCa++++

CaCa++++

MgMg++++

MgMg++++

MgMg++++

HH++HH++HH++

KK++

KK++

HH++

KK++

CaCa++++

CaCa++++

NHNH44++

NHNH44++

NHNH44++

Clay

ClayClay

Clay

Soil SolutionSoil Solution

Soil pHSoil pH is is the most the most important important soil test soil test conductedconducted

azaleasazaleas VegetablesVegetables

Estill County Soil Test Results Estill County Soil Test Results

Elemental Sulfur Reduces pHLime Increases pH

Gypsum Has No Effect

Soil Testing - Nitrogen

• Nitrogen is the fertilizer needed most in KY Nitrogen is the fertilizer needed most in KY soilssoils

–Very little soil nitrogen is in the plant available Very little soil nitrogen is in the plant available form so soil testing is not generally form so soil testing is not generally recommendedrecommended

–Soil testing can be used to diagnose Soil testing can be used to diagnose excessive fertilizer applicationsexcessive fertilizer applications

–Plants take up inorganic (NOPlants take up inorganic (NO3 3 and NHand NH44) )

nitrogen – nitrogen – Organic sources must be Organic sources must be mineralized before they are plant availablemineralized before they are plant available

Fertilizer Recommendations Fertilizer Recommendations Soil Testing is the only way to know for sure how Soil Testing is the only way to know for sure how much phosphorus and potassium is needed. much phosphorus and potassium is needed.

If soil test phosphorus is above 100 lbs/a PLEASE DON’T apply any more phosphorus

Fertilizer Recommendations Fertilizer Recommendations Soil Testing is the only way to know for sure how Soil Testing is the only way to know for sure how much phosphorus and potassium is needed. much phosphorus and potassium is needed.

Fertilizer AnalysisFertilizer Analysis

34-0-0 34% N – 0% P2O5 – 0% K2O5-5-5 5% N – 5% P2O5 – 5% K2O

Analysis Nutrient Concentration

Fertilizer recommendation is for 1 lb N per 1000 sq ft how much 34-0-0 or 5-5-5 is needed?

1 lb N/1000 sq ft0.34 lb N/lb material

3 lbs 34-0-0 per1000 sq ft

Nutrient Content of ManureNutrient Content of Manure

Other Essential ElementsOther Essential Elements

Sulfur, Calcium, Magnesium, Zinc, Sulfur, Calcium, Magnesium, Zinc, Iron, Copper, Manganese, Boron, Iron, Copper, Manganese, Boron, Molybdenum, and ChlorineMolybdenum, and Chlorine

Are almost always adequate if soil pH is adjusted for the crop

Questions???