A
acidic: describes a substance that is low on the pH scale and loses hydrogen in water. Examples of acidic substances include lemon juice and vinegar.
aeroponics: a method of growing plants without any soil or substitute material.
antibiotic: a substance that destroys bacteria or stops it from growing.
atmosphere: the blanket of air surrounding the earth.
B
bacteria: tiny organisms found in animals, plants, soil, and water.
basic: describes a substance that is high on the pH scale and gains hydrogen in water. Examples of basic substances include soap, baking soda, and ammonia.
BCE: put after a date, BCE stands for Before Common Era and counts years down to zero. CE stands for Common Era and counts years up from zero. The year this book was published is 2015 CE.
bedrock: the layer of solid rock under soil.
C
carbon: an element found in all living things.
carbon dioxide: a gas formed by the rotting of plants and animals and when animals breathe out.
cell: the smallest, most basic part of a living thing.
chemical: the pure form of a substance. It has certain features that can react with other substances. Some chemicals can be combined or broken up to create new chemicals.
civilization: a community of people that is advanced in art, science, and government.
climate change: changes to the average weather patterns in an area during a long period of time.
commercial: large businesses that produce large quantities of something.
component: an important part of a system or mixture.
composting: recycling food scraps to form humus for the soil.
contaminate: to pollute or make dirty.
crop: a plant grown for food and other uses.
cuneiform: a system of wedge-shaped letters created by ancient civilizations.
decay: to break down and rot.
E
ecosystem: a community of living and nonliving things and their environment. Living things are plants, animals, and insects. Nonliving things are soil, rocks, and water.
element: a pure substance that can’t be broken down, such as hydrogen, oxygen, carbon, or gold.
eluviate: when materials move down through the soil to the layer below.
environment: everything in nature, living and nonliving, including plants, animals, soil, rocks, and water.
erosion: the gradual wearing away of rock or soil by water and wind.
expand: to spread out and take up more space.
F
fertilizer: any substance put on land to help crops grow better.
filter: to pass a liquid through something to remove unwanted material.
food chain: a community of animals and plants where each is eaten by another higher up in the chain.
forensics: using scientific methods to investigate and solve a crime.
fungi: organisms that grow on and feed on rotting things.
G
gravity: the force that pulls things down toward the surface of the earth.
graze: to eat grass.
H
habitat: a plant or animal’s home.
horizon: a layer of soil.
humus: soil formed from decaying leaves and organisms.
hydrogen: the most common element in the universe. Hydrogen and oxygen are the two elements in water.
hydroponics: a method of growing plants in a material other than soil.
I
Ice Age: a period of time when ice covered a large part of the earth.
infect: when microbes invade your body and make you sick.
inorganic: not living.
landscape: a large area of land with specific features.
leaching: when minerals and other matter move out of the topsoil.
listeria: a bacteria that’s unhealthy for animals and people.
livestock: animals raised for food and other products.
M
mammal: a warm-blooded animal, such as a human, dog, or cat, that can keep itself warm. Mammals feed milk to their young and usually have hair or fur covering most of their skin.
manure: animal waste.
Mesopotamia: an area of ancient civilization between the Tigris and Euphrates Rivers in what is now called Iraq, Kuwait, and Syria.
microbe: a tiny living or nonliving thing. Bacteria and fungi are living microbes that are also called microorganisms.
microscopic: something so small that it can be seen only with a microscope.
minerals: nutrients found in rocks and soil.
N
natural resource: something from nature that people can use in some way, such as water, stone, and wood.
nutrients: substances in food, soil, and air that living things need to live and grow.
O
organic matter: rotting plants and animals that give soil its nutrients.
organic: something that is or was living.
organic farming: raising livestock and crops in a natural way.
organism: a living thing.
P
parent material: material that eventually becomes soil, such as rock.
particle: a tiny piece of matter.
pesticide: a chemical used to kill pests, such as insects.
petri dish: a shallow dish with a loose cover that’s used to grow bacteria and other microscopic organisms in a lab for scientists to study.
photosynthesis: the process in which plants use sunlight, water, and carbon dioxide to create energy.
pH: the scale people use to measure how acidic or basic something is.
pictograms: the symbols in the first written languages, based on pictures instead of letters.
pneumonia: (noo-MOW-nyuh) an infection of the lungs.
R
resistant: something that stands against something else.
rooting: when pigs push around the soil with their snouts.
root rot: when the roots of a plant rot, usually because of too much water.
runoff: when fertilizers and pesticides leach out of the soil and into the water system.
S
silt: particles of fine soil, rich in nutrients.
soil: the top layer of the earth, in which plants grow.
soil respiration: when carbon dioxide is released into the atmosphere from the soil.
species: a group of plants or animals that are related and look like each other.
subsoil: the layer of soil below the topsoil.
substance: the material that something is made of.
T
topsoil: the top layer of soil.
toxic: something that is poisonous.
tropics: the area near the equator. This is the imaginary line around the earth halfway between the North and South Poles.
W
water cycle: the continuous movement of water from the earth to the clouds and back to the earth again.
water table: the underground water supply for the planet.