Horticulture - Soil Pt. 2

Roots provide

Anchorage, transportation, absorption

Roots grow where there is

Water and Oxygen

Tree’s absorbing roots are located

the top 12” of soilwhere moisture and nutrients are abundant.

Soil Solution

the liquid in soil that contains dissolved nutrients, minerals, and organic matter, which plants absorb for growth.

The water attached to the surface of soil particles

Field Capacity

Amount of water in the soil after an irrigation event (ex: rainfall)

Leaching

the process by which soluble nutrients are washed out of the soil due to excessive water movement.

Macropores

large soil pores that allow for air and water movement

Micropores

small soil pores that retain water and nutrients but limit air movement.

Soil Texture

refers to the classification of soil based on the size of its particles, including sand, silt, and clay, which affects water retention and nutrient availability.

Sand

the coarsest soil particle, largest in size compared to silt and clay, allowing for good drainage and aeration.

2.00-0.05mm

Silt

the soil particle size between sand and clay, providing moderate drainage and nutrient retention. Silt feels smooth and retains more water than sand.

0.05-0.002mm

Clay

the smallest soil particle size, known for holding water and nutrients effectively, but it can lead to poor drainage and aeration.

Less than 0.002mm

Sandy Soils

Soils that contain a high percentage of sand, promoting excellent drainage but low nutrient retention.

• Faster water movement

• Excellent aeration

• Decreased water holding capacity

• Decreased nutrient holding capacity

Clay Soils

Soils that have a high percentage of clay particles, which retain moisture and nutrients effectively but may suffer from poor drainage and aeration.

• Slower water movement

• Poorly aerated

• Increased water holding capacity

• Increased nutrient holding capacity

Soil Texture contributes to

the composition and properties of soils, including drainage, aeration, and nutrient retention.

• Chemistry of soil

• Surface area

• Ability to hold nutrients

Clay plays a major role in

Soil chemistry

Clay has 1000x more __ than coarse sand

surface area

Fertility

the ability of soil to support plant growth by providing essential nutrients, moisture, and a suitable environment for root development.

• Clay vs. Sand

You can find nutrients in 2 areas in the soil

the soil solution and the solid phase of the soil/particle bond

Cation Exchange Capacity (CEC)

the ability of soil to hold and exchange cations, which are positively charged ions essential for plant nutrition.

• Hold against the forces of leaching

• Ion is a charged particle either + or -

Cation is , Anion is _

Positive, negative

The binding sites on soil particles are

negatively charged, allowing for cation exchange.

Gardeners want a __ cation exchange capacity

High

Nutrients are primarily available to the plant in the

soil solution

Soil texture with a higher amount of CEC is

Better than soil texture with lower amounts

Ions

that carry a positive or negative charge and are essential for nutrient exchange in the soil.

K+

is the potassium ion, essential for plant growth, helping to regulate various physiological processes.

H+

is the hydrogen ion, playing a crucial role in soil acidity and nutrient availability for plants.

Ca+2

is the calcium ion, vital for cell wall structure and stability, as well as promoting root development and overall plant health.

NH+4, NO-3

are ammonium and nitrate ions, which serve as important nitrogen sources for plants, contributing to amino acid and protein synthesis.

Mg+2

is the magnesium ion, essential for chlorophyll production, enzyme function, and overall plant metabolism.

HPO4-2

Phosphorus

H2PO4-

The dihydrogen phosphate ion, an important intermediary in the phosphorus metabolism, playing a critical role in energy transfer as part of ATP

SO4-2

The sulfate ion, a crucial component in plant nutrition, primarily involved in protein synthesis and enzyme function.

Carbon and Oxygen have no

Ionic form

Organic Matter

Plant and animal residues in soil that decompose, providing essential nutrients and improving soil structure.

• Different than mulch

• Any compound high in Carbon

• Either alive or dead organisms

What is the main decomposer of Organic Matter?

Soil microorganisms such as bacteria and fungi that break down organic material into simpler substances for nutrient cycling.

• Breaks down residue faster if particles are smaller

Organic Matter is

Dynamic - always changing

Organic matter contains

varying degrees of nutrition

Humus

the dark organic material in soil formed by the decomposition of plant and animal matter, essential for soil fertility.

• Improves soil structure

• Increases holding capacity

• Improves water relations

• Improves pore space

CEC ranges from

200-400, achieve this by continuously adding organic matter to soil

Soil Structure

refers to the arrangement of soil particles and the pore spaces between them, influencing water movement, root growth, and overall soil health.

Good soil structure

allows for improved drainage and aeration, promoting healthy plant growth and root development. Ability of soil to form clumps

Soil structure is improved by

the addition of organic matter, humus Microbes, cultivation practices, and appropriate crop rotation.

Healthy Soil

is soil that has a balanced composition of organic matter, minerals, and microorganisms, which supports plant growth and maintains ecological balance.

Degraded Soil

is soil that has lost its health and fertility due to factors like erosion, contamination, or loss of organic matter, leading to diminished productivity.