The warm climate and rich soil of southern Brazil made the area produce abundant harvests. By 1990, the soil in the region had been farmed so many times, its productivity was ruined. Before then, farmers had tilled (plowed) the soil. This left the soil loose and vulnerable. The heavy rains in Brazil would wash away the soil.

After 1990 farmers there then began turning to zero- tillage farming. The farmers and scientists in Brazil came up with a method of planting ‘cover crops’ on the farmland to keep the soil intact, and then simply slicing a thin groove in the ground and dropping seeds in when it was time to plant a commercial crop. This method reduced erosion in Brazil by 90%.

reduces a farmer’s expenses because less fuel and labor are used to plant reduces erosion the soil holds more water and organic nutrients plants grow better in no-till soil

Agriculture: the practice of raising crops and livestock for human use and consumption Cropland: land used to raise plants for human use Rangeland: land used for grazing livestock, also known as pasture Soil: a complex plant-supporting system consisting of disintegrated rock, organic matter, water, gases, nutrients, and microorganisms

By over-farming humans are greatly reducing its ability to support life for long time periods Soil degradation can cause considerable environmental damage, for example turning grasslands into deserts

For the 80 million people added to the Earth every year, it loses about 15 million acres of productive cropland Europe currently has the highest proportion of degraded land of any other continent

Humans began using agriculture about 10,000 years ago. Agriculture most likely began as the hunter- gatherers brought back seeds and nuts to their villages, some fell to the ground, began to grow, and people realized they could plant.

Farming using human and animal power is traditional agriculture. Subsistence agriculture is a family farming only to produce enough for themselves. Intensive traditional agriculture is farming to produce excess food to sell at market.

Replaced animal power in farming with machine power Appeared after the Industrial Revolution Boosted crop yields by intensifying irrigation and introducing synthetic fertilizers, while the creation of chemical pesticides reduced weeds and pests

In order to be efficient, industrialized agriculture requires that vast areas be planted with only one type of crop. The uniform planting of only a single crop is called monoculture. Today, monoculture is used on over 25% of Earth’s croplands.

In the mid-1900s, a revolution was sparked around the world that encouraged the introduction of industrialized agriculture to developing nations. This greatly increased the productivity of developing nations and helped many regions avoid starvation.

Parent Material: the base geological material in a particular location (rock/sediment/dunes/lava/volcanic ash) Bedrock: the continuous mass of solid rock that makes up Earth’s crust.

Erosion: the dislodging and movement of soil from one area to another. Weathering: the physical, chemical, and biological processes that break down rocks and mineral, turning large particles into small particles (physical, chemical, & biological weathering).

Soil is made of roughly 50% mineral matter, 45% air and water, and 5% organic matter. Formation begins when the lithosphere’s parent material is exposed to the effects of the atmosphere, hydrosphere, and biosphere. Weathering, erosion, and the deposition and decomposition of organic matter are most responsible for the formation of soil.

After small particles are produced from the parent material, wind, water, and organisms move and sort them. Distinct layers of the particles begin to develop, and each layer is known as a soil horizon. The vertical look at the layers, from the surface to the bedrock down below is known as a soil profile.

The six major horizons in a soil profile are the O, A, E, B, C, and R horizons. The most important horizon in agriculture is the A horizon, more commonly referred to as topsoil. Topsoil is the most nutritive horizon for plants.

Minerals move down through a soil profile in a process known as leaching

Color Texture Structure pH

Soil color indicates its composition and fertility. Dark soils are usually rich in organic matter, while gray to white soils often mean leaching occurred or there is low organic matter.

Soil texture is determined by the size of the particles. ‘Clay’ consists of particles less than mm in diameter, ‘silt’ particles mm, and ‘sand’ particles mm. Soil with a relatively even mixture of all three textures is called loam.

Soil structure is a measure of the ‘clumpiness’ of the soil.

Soil pH is the degree of acidity or alkalinity of the soil.

Rainfall and temperature influence agriculture and vary from region to region.

Areas with a lot of rainfall, such as tropical rainforests, often fall victim to leaching. Many farmers there use ‘swidden’ agriculture- in which the farmer cultivates a certain plot for a year or two and then abandons it for another plot and lets the forest grow back there.