Soil Texture

The inorganic matter in soil is made of small particles of rock. These particles are ….(3)

• sand

• silt

• clay

Sand

Soil particles are larger than silt and clay particles. Because of how large it is, water passes quickly through sandy soils.

Silt

Silt is finely ground particles of parent rock. Its particles are larger than clay, but smaller than sand.

Clay 

Clay has the smallest particles, so clay retains water because water passes through it very slowly.

7 properties of minerals

• biota

• primary productivity

• water retention

• mineral content

• organic nutrient content

• water drainage

• air spaces

7 properties of sand 

• biota - low

• primary productivity - low

• water retention - low

• mineral content - high

• organic nutrient content - low

• water drainage - high

• air spaces - high

7 properties of silt  

• biota -medium

• primary productivity -medium

• water retention - medium/low 

• mineral content - high

• organic nutrient content - low

• water drainage -medium

• air spaces -low

7 properties of clay 

• biota - high (but oxygen is limited)

• primary productivity - variable 

• water retention - high 

• mineral content - high

• organic nutrient content -high

• water drainage -low

• air spaces -low

Soil supports higher primary productivity when (3)

• soil can store adequate water

• soil mineral content is high

• humus is present

Soil can store adequate water

• Water passes so quickly through sandy soils, that plant roots are unable to absorb much of it. 

• In clay soils, water is sometimes so slow to move that roots are damaged by the high water content. 

• Waterlogged soil has too much water and productivity is low. Therefore, a mixture of soil particles will support the highest primary productivity,

Soil mineral content is higher

When soil contains sand and silt, which is very fine ground rock, it will be high in minerals that are essential to plant growth.

Humus is present

 Organic matter provides plants with nutrients. When manure and decaying organisms are completely decomposed by soil organisms, they produce humus, which helps retain water and air, and prevents waterlogging.

Loam soil

Soil that has a balanced mixture of sand, silt, and clay. Therefore, they are the most productive (best for agricultural purposes).

• Good drainage 

• Water / nutrient holding 

primary productivty

the rate at which organisms like plants and algae convert solar energy into chemical energy through photosynthesis, creating biomass or organic matter