Intro to Soils PowerPoint Worksheet

Intro to Soils PowerPoint Worksheet

HW 2.3

  1. Define soil 

Soil is defined as Mineral & Organic material that supports plant growth on the earth’s surface, and mixtures of particles of rock, organic materials, living forms, air, water



  1. What soil resources aid in supporting life?



  • Oxygen: needed for adequate root growth

  • Temperature: soil absorbs heat from the sun – loses heat to atmosphere (plant growth and seed germination)

  • Water: plant growth

  • Carbon: organic matter

  • Nutrients: minerals




  1. How does Soil originate? Describe at least 4 specific but separate processes that could lead to soil.

  • All soil originated as rocks

  • Powerful forces act on the rocks to break them down into smaller fragments.

  • Water penetrates the cracks in the rock and when it freezes the water acts as a wedge to split the rock.

  • Rivers, glaciers, landslides and avalanches cause rock particles to grind against each other wearing them down.



  1. What are the 5 factors that are responsible for soil development?



  1. Parent material

  2. Climate

  3. Variation in the earth’s surface (topography)

  4. Plant & animal life

  5. Time



  1. What is soil Made of?

  • Mineral Matter: about 45% of soil (partially decomposed rock material (sand, silt, clay)

  • Organic Matter: about 5% of soil (partially decomposed plant & animal matter)

  • Air: about 25% of soil (constant fluctuation as soil is dry and wet)

  • Water: about 25% of soil



  1. How does water get in the soil?

Water gets in the soil due to infiltration



  1. How do plants use soil?

  1. Anchorage – roots

  2. Water – absorbed through roots

  3. Oxygen – all living organisms need oxygen

-plants release oxygen during photosynthesis

and consume oxygen during respiration 

-good soil aeration needed for below ground

plant parts to get oxygen

  1. Nutrients – of the 16 essential nutrients for plant growth – 13 are obtained from the soil 

-root hairs absorb the nutrients dissolved in soil water

  1. How long does it take healthy soil to form?

100-1000 years 



  1. List the different soil layers, and briefly describe what makes each one unique?

O Horizon (Organic Layer) – The top layer, made of decomposed leaves and organic material, rich in nutrients.

A Horizon (Topsoil) – Contains a mix of minerals and organic material, dark in color, and supports most plant life.

E Horizon (Eluviated Layer) – Light-colored layer where minerals and nutrients are leached (washed out), often found below the A horizon.

B Horizon (Subsoil) – Accumulates minerals and nutrients leached from upper layers, denser and lighter than topsoil.

C Horizon (Parent Material) – Consists of broken-down rock pieces, with little organic material, acting as the base layer of soil.

R Horizon (Bedrock) – The solid rock layer beneath all soil layers, not yet broken down into soil



  1. What do we call the different particles of soil when categorized by size. What are the size ranges for each?

Soil particles are categorized as sand, silt, and clay, based on their size. Sand particles are the largest (0.05–2 mm), silt particles are medium-sized (0.002–0.05 mm), and clay particles are the smallest (less than 0.002 mm).

  1. When we combine the three different sizes of soil, what different categories of soil do we have? How much of each size particle does each type of soil have? 




  1. Define porosity and permeability and differentiate between the two.

Porosity: Measure of spaces per volume of soil 🡪 holds more H2O/air

Permeability: how fast H2O/air move down in soil.



  1. Which has more porosity between clay soils and sandy soils?

Clay soils



  1. What are loam soils?

Loam soils are Mixes of all sizes of soil, with medium permeability and porosity



  1. What is the upside of high input farming?

The upside of high input farming is that it produces a lot of food.



  1. What are the two major downsides to tillage farming?

Plowing brings up topsoil (A) layer to O layer and loose soil is then exposed to wind and water 🡪 carried away- soil erosion.



  1. What is terracing? 

Terracing is when slope converted into broad terraces to retain H2O and soil

  1. What is contour farming? 

Contour farming is plowing and planting in rows across slope of land (slow water and soil runoff)



  1. What is strip cropping?

Strip cropping is planting a row of 1 type of plant, then planting a row of another type of plant.



  1. What are windbreaks?

Windbreaks slow wind down before it hits farm soil.



  1. What are the pros and cons of inorganic fertilizers?

Inorganic fertilizers provide a quick and efficient source of nutrients for plants, leading to rapid growth. However, they can lead to soil degradation, water pollution, and disruption of natural ecosystems if overused.

  1. What are three organic fertilizers

1) Animal manure: dung/urine of animals

2) Green manure: plants plowed into soil

3) Compost: semi-broken down org. matter



  1. Why is locally grown food bought from farmers markets typically better for the environment?

Locally grown food bought from farmers markets typically better for the environment because it lowers fuel emissions of greenhouse gasses, less gas is used, less transport of pests, less packaging, lower costs of produce, and revenues remain local