Composition of Soils

• An average soil sample is 45% minerals, 25% water, 25% air and 5% organic matter

• Healthy soil has many parts

• The soil’s texture comes from the different sizes of the rock and mineral particles

  • sandy soils have larger particles

  • silt has fine particles (very small broken pieces of rock)

  • clay soils have particles that are too fine to be distinguished with a microscope (tiny particles of soil that hold water well, provides nutrients)

Layers of Soil

• O horizon, or topsoil - made of decaying organisms and plant life; responsible for plant production

• A horizon - mixture of organic material and inorganic products of weathering

• B horizon, or subsoil - dense layer of mostly fine material that has been pushed down from the topsoil

• C horizon, or soil base - located above bedrock and is made of parent, organic, and inorganic material.

loam: soil with no dominant particle size that contains a mixture of sand, silt, and humus

humus: a group of natural compounds composed of decaying plants/dead and living microorganisms, adds nutrients in the soil

topsoil: top layer of soil containing humus at its surface and decomposing vegetation at its base; the most fertile soil/best for plant growth

subsoil: dense layer of soil containing fine material that has moved downward

- subsoil and bedrock are formed over a long period of time by the action of water

A life cycle is a series of stages a living thing goes through during its life.

All plants and animals go through life cycles.

Stages of Life: All life cycles start at birth, end with death, and involve growth and reproduction.

Think about life cycles you know about -- how do humans grow from babies to adults?

What about pets?

Life Cycle of Plants

• start as seeds and then form flowers/fruit

• plants start as seeds

• germination - when a seed starts to grow

• when a plant is mature, it produces flowers.

• flowers are fertilized by animals like honeybees or sometimes by wind

• after a flower is fertilized, most plants make seeds in the form of fruit

• the seed inside the fruit can be planted and grow into a new plant

• cycle starts over again!

Life Cycle of Animals

• animals start from eggs or live birth

• baby animals grow and change into adolescents and eventually become adults

• adult animals look for a mate to begin the life cycle all over again

• each type of animal has their own unique life cycle

• when babies are born or hatch from eggs, some look much like their parents, like kittens and horses, while other baby animals look different from their parents, like tadpoles which will turn into frogs.