4.2/4.3

Parent material

rock from which the soil was formed, so it's basically just minerals

Young soil

soil that has not grown many plants, soil that is newly formed

Mature soil

soil that is well formed and has horizons

Old soil

soil that has lost its nutrients been used for agriculture/growing plants for a long time (exhausted)

Soil profile

diagram that shows all the layers of the soil

Topsoil

top soil that contains humus

Subsoil

layer underneath the topsoil that contains minerals

Loam

soil capable of growing plants

Cation exchange capacity

the ability to give up cations to plants

Pedocal

soil that occurs in dry regions and is high in Ca+

Pedalfer

soil that occurs in wet regions and is high in Al and Fe (as neither element leaches out); not good for growing plants

Soil erosion

loss of soil, by wind or water

Ground cover

plants growing that hold the soil in place

Difference between soil and dirt

soil is organized into horizons, dirt is misplaced soil

Why is topsoil considered nonrenewable?

it is consumed faster than it can regenerate (500-1000 years)

Two functions for soil

providing nutrients to plants, regulating water

Two most common parent materials for soil in the U.S.

Calcium carbonate (limestone) or silicon based stone (sandstone)

Why is limestone based soil good for farming?

its ability to neutralize soil acidity

Three main soil horizons

O: Humus, mostly organic material; A: Topsoil, a layer of organic materials and minerals mixed together (usually mixed by plowing or tilling); B: Subsoil, composed primarily of mineral material with very little organic material mixed in; C: Least weathered, made mostly of parent material; D: Bedrock

E horizon

A layer in some soil profiles w/ leaching of minerals and organic matter, leading to a lighter color compared to the layers above and below it (older and forest soils). Only found in pedalfer

Three kinds of soil particles in order of size

Sand, silt and clay

Ideal loam composition

40% sand, 40% silt, 20% clay

Main ions in soil

Ca, Mg, K, NH4, H, and Na

Ions usually present in basic soil

hydroxide ions (makes it basic)

Climate producing acidic soils

wet/rainy

Why are soils usually low in nitrates and potassium?

because they leech out easy with water (a soil with a lot of rain); most common reason for deficiency would be a wet climate or irrigation - same for soils low in Ca

Why are soils usually low in phosphates?

soil based on rock with a lack of phosphate (dry soils)

Why does no-till agriculture prevent erosion?

No-till systems enrich the soil with organic matter, increase soil water-holding capacity, and protect crops during periods of drought and flooding. The crop residue left on the soil surface also prevents wind and water erosion, benefitting water and air quality.

How does crop rotation increase the nutrient content of soil?

divide field into sections, move plants in different always plow under one (different plants take different nutrients, rotation prevents the leaching of too much of the same nutrient in one area)

How does contour plowing prevent erosion?

method that respects land area, contour lines, or natural shape; plowing along CL the farmer creates mini terraces which discourage swift water run off—water doesn't erode soil, but soaks into it, and can be used by plants for growth.

Flooding kills plants

suffocates them/cuts off their access to O2

Organisms in flooded soil

anaerobic bacteria (make methane/hydrogen)

Nutrients added by animal waste to soil

nitrates

Why do you want clay in soil?

Clay is good at holding ions/nutrients

Why do you want sand in soil?

nutrients go through it very quickly

Why do you want silt?

Silt adds structure to the soil