Soil on Earth

Write five things that comes to mind when you hear the word “soil”. WARM UP

What is Soil? Soil is a mixture of minerals, organic material, air, water, and microorganisms.

Soil Composition 45% are minerals. Soils lose minerals by erosion, leaching (the movement of minerals dissolved in water), and by plant uptake. 5% is organic matter. Organic matter is matter composed of decayed remains of living organisms, leaves, roots, insects... It is also called humus and is the glue that holds mineral particles together, helps form pore spaces, and increases fertility of the soil. 25% is air. Fertile soil also needs to contain air. Air in soil similar to air in atmosphere and oxygen is especially important; turning and mixing soil called tilling and this is how air is introduced to the soil. 25% is water (soil moisture).

Earth Soil Composition

Mars Soil Composition 55% 45% Data taken at the Viking 1 landing site:

outube.com/watch?v=60KBrOFQrTA ay-s mars-look-when-it-had-water

Soil Moisture Soli moisture is water held in soil pores. If soil contains too much water, it becomes saturated. Optimum water content is field capacity (water to air ratio = 50% to 50%). When soil moisture is gone - wilting point.

Soil Moisture Three States of Moisture in Pores

Soil Organisms Earthworms mix and aerate the soil. Bacteria help add nitrogen to the soil by converting atmospheric nitrogen to plant-available forms such as nitrates. Fungi and insects improve structure and add organic matter. Rodents help to mix the soil.

Soil Structure Soil structure is the arrangement of mineral particles and organic matter within a soil. The parts of a soil are sand, silt, and clay. If a soil is high in sand – the soil will have excessive drainage. If soil is high in clays, it prevents water infiltration, is highly erodible, and does not support crop growth.

Next Steps… Why is it important for us to understand the soil on Earth before we go to Mars? The rest of the week we will look at both Earth and Martian Soil.

SOIL TEXTURE TRIANGLE

SOIL TEXTURE TRIANGLE ACTIVITY 60% Sand 30% Silt 10% Clay 1. WHICH SOIL TYPE CONTAINS 60% SAND, 30% SILT and 10% CLAY ?

SOIL TEXTURE TRIANGLE 60% Sand

SOIL TEXTURE TRIANGLE 60% Sand 30% Silt

SOIL TEXTURE TRIANGLE 60% Sand 30% Silt 10% Clay IT IS SANDY LOAM!!!

SOIL TEXTURE TRIANGLE 60% Sand 30% Silt 10% Clay