Horticultural Soils

Obj. 5.01 Discuss horticultural soils

Organic Partially decomposed

material mined from the swamps

Good moisture holding properties

Peat Moss

Inorganic Mica material matter Commonly used to start

seed and cuttings Holds moisture Neutral pH

Vermiculite

Inorganic Natural volcanic material Help with soil aeration

and water holding capacity

Perlite

Dead plant or animal tissue Contains carbon

Organic Matter

Decayed organic matter Used for soil conditioning and fertilizer

Compost

Organic Larger matter added to

some horticulture media to promote drainage

Adding bark usually makes mix heavier

Used in tree and shrub production

Bark

Organic Dehydrated remains

of acid bog plants Holds moisture Very acidic Commonly used to

line wire hanging baskets

Sphagnum Moss

Soil is sterile pH is neutral Soil is disease and weed free Good for starting disease sensitive seeds

(tomato) Easy to control the nutrient content of the soil Improves crop uniformity Easy to create a horticulture soil for particular

plant needs

Advantages of Horticultural Soils

Expensive Light weight

Disadvantages of Horticultural Soils

Sawdust has a high carbon to nitrogen ratio

Sawdust makes nitrogen unavailable for plant use

Wood shaving have a high carbon to nitrogen ratio Wood shaving makes nitrogen unavailable for

plant use

Additional Materials Used

Properties of Soils

Obj: Discuss the soil profile and soil sampling for surface and subsurface

layers.

Soil layers are called horizons

O Horizon A Horizon B Horizon C Horizon R Horizon

Soil Profile

Rich in organic matter Dark in color Most fertile layer

O Horizon

Topsoil Just below O Horizon Home to earthworms and soil organisms Brown in color due to the organic matter in

soil

A Horizon

Subsoil Clayey soil High mineral content Usually brown or

reddish due to large amount of clay

B Horizon

Parent material Consist mainly of

clumps of un-weathered rocks

C Horizon

Bed rock Cannot be dug by hand Very few roots can penetrate the bedrock

R Horizon

A Soil Profile

As you can see, soil is made up of several

layers…much like this pudding Imagine the layered pudding representing

different layers of the soil horizon Top the pudding off with a gummy worm, as

the gummy represents the critters of the topsoil

Enjoy!

An Edible Soil Profile

Soil Structure & Texture

Soil structure: How the soil particles fit together

Soil texture: Soil characteristic determined by the percentage of sand, silt, and clay

Soil Structure

Sandy Soil

Sandy soils typically have a loose soil structure

Sand has the largest particles (.05-2 mm)

Sandy soils have low moisture and nutrient holding capacity

Silty Soil

Silty soils have a granular soil structure

Granular soil structure is best for plants

Silt has medium sized particles (.002-.05mm)

Silt has a good moisture and nutrient holding capacity

Clayey Soil

Clayey soils have a blocky or platy structure

Clay has the smallest sized particles (<.002mm)

Clayey soils have a high water and nutrient holding capacity

Loam

Loam has almost equal parts of sand, silt and clay

This is the ideal texture for most non container outside plants

Textural Triangle

Used to determine soil textural class from the percentages of sand, silt, and clay in the soil

How do you determine these percentages? SOIL SAMPLE!

Practice using the following worksheet by

using the textural triangle!

Try the Textural Triangle