mocks cramming - topic 5 - soil Flashcards
Soil inputs
Minerals: The minerals of a soil come from the weathering of the parent material by physical, chemical and biological processes.
Organic matter: Organic matter comes from the living organisms that are on and in the soil. Soil and vegetation develop together. During succession, the early plants colonize the area before the soil has really developed. When the early plants die, they add organic material to the soil
gases: Certain plants fix atmospheric nitrogen and change it into nitrates and ammonia compounds in the soil. The nitrogen fixation is a process that forms an input into the soil system
Water: The way in which water enters the soil is dependent one whether the soil is on a slope and where it is on that slope. At the top of a slope the soil receives most water through direct precipitation.
soil stores
- organic matter
- organisms
- minerals
soil outputs
- physical erosion: through the action of wind, water and plants and animals
- organic erosion: Plants take nutrients and carbon dioxide from the soil for growth and to photosynthesize.
- leaching water flowing vertically through the soil transports nutrients in solution downward in the soil profile. Many of these nutrients can be completely lost from the soil profile if carried into groundwater and then horizontally transported into rivers, lakes, or oceans.
Soil Profile
four main horizons – O, A, B and C. Soils will not always have all the horizons.
Soil - Organic horizon (referred to as the O horizon)
is on the top of the soil
- includes all the DOM that accumulates on top of the soil.
- Initially the remains can be identified but as decomposition progresses the DOM becomes an unrecognizable jelly like substance (humus) that mixes into the soil over time.
Soil - A horizon
the top soil or mineral layer.
- This layer is usually dark in colour due to the high proportion of organic matter.
- The high organic content means it is a zone of highest biological activity. This layer has often lost its clay as it has been eluviated or washed out. This is often absent.
Soil - B horizon
the sub-soil
- tends to be the zone of illuviation or accumulation.
- Minerals and particles are washed into this horizon from the ones above.
- Plant roots are likely to be found in this layer but very little humus is found here.
Soil - C horizon
the decomposed parent material. In most cases this layer is not really affected by soil processes but it has weathered. This layer may contain large lumps of parent material.
Soil texture
is linked to the relative proportions of sand, silt and clay particles. There are other sizes of particles but these three are the most important.
Soil structure
- describes the way the sand silt and clay particles stick together
- affected by the presence of organic matter and soil organisms.
Fertilizers (3):
Nitrogen-based Fertilizers: Ammonium nitrate and urea were commonly used to provide essential nitrogen for plant growth.
Phosphorus-based Fertilizers: Superphosphate and diammonium phosphate supplied phosphorus, crucial for root development and energy transfer.
Potassium-based Fertilizers: Potash (potassium chloride) helped with plant metabolism and disease resistance.
Pesticides (3):
Insecticides: DDT (dichlorodiphenyltrichloroethane) and organophosphates were used to control insect pests.
Herbicides: Atrazine and glyphosate were employed to manage weeds.
Fungicides: Copper sulfate and sulfur compounds were applied to combat fungal diseases
two kinds of farming
Arable - Focus on crops (Corn, Rice, Wheat)
Pastoral - Any animals or livestock
intensive commercial crop production includes the use of (7)
- High-yielding crop varieties including genetically modified organism (GMOs).
- Fertilizers that provide nutrients to encourage maximum growth.
- Herbicides to kill weeds that compete with the crops for space, water and nutrients.
- Insecticides to kill insects that eat and damage the plants.
- Water (either via rainfall or irrigation) to encourage maximum growth.
- Mechanical equipment that allows large areas to be effectively farmed.
- Automated technologies that can be used to extend the scale of farming by reducing the amount of labour required to manage larger fields, (eg. automatic irrigation systems.)
The impacts (Animal Production) (4)
- High density of animals increases the risk of rapid spread of disease through the animal population.
- Ethical concern over keeping animals under such confined conditions.
- Regular use of medication such as antibiotics to prevent diseases. Use of antibiotics increases the risk of developing resistance within bacteria. This makes future infections more difficult to treat.
- High concentration of organic waste matter produced that can pollute water systems.
environmental impacts (crops)
-
Pesticides kill non-target organisms and can reduce overall biodiversity. Some non-biodegradable chemicals, (eg. DDT), can bioaccumulate and biomagnify building up concentrations through the food chain.
-Fertilizers - eutrophication of waters - Water for agriculture competes with other uses of limited water resources
- Monoculture increases the risk of disease, affecting all crops.
- Mechanical equipment uses non-renewable fossil fuels and emit greenhouse gases, for instance carbon dioxide and nitrous oxides.
- Soil degradation, for example excessive irrigation, can increase nutrient run-off and also cause salinisation.
the great dust Bowl
During the 1930s in the USA, dust storms swept across the Midwestern states of the USA. This period is commonly referred to as the ‘Dust Bowl’ and brought the issue of soil loss to global attention.
Prolonged drought in the 1930s dried out the soil. When wind storms occurred, large amounts of topsoil were swept into the air causing vast dust storms. The cost was immense with no harvests and damage to property. Many people starved or died from dust penetrating into their lungs causing dust pneumonia. Thousands of farmers lost their livelihoods and migrated to urban areas seeking employment. Unfortunately there were few opportunities in the cities and towns during this period of the Great Depression.
The Dust Bowl prompted investment into the study of soils to find solutions to the problem. In 1935, the US Soil Erosion Act came into force to encourage soil conservation practices. Although our understanding of soils and soil conservation has improved since the Dust Bowl, soil loss and degradation continues to be a problem around the world.
Fertile soils
- essential nutrients and minerals
- Organic matter which provides sufficient soil moisture holding capacity and good soil structure
- a suitable pH
Threats to soils (4)
- Water erosion.
- Wind erosion.
- Chemical degradation, such as salinisation, acidification, nutrient depletion and chemical pollution.
- Physical degradation, such as soil compaction.
water erosion phases (3)
- Detachment: When the raindrops hit the soil, it frees some of the soil particles. Then run-off detaches more soil particles as it flows.
- Transport: The flow of the water carries the soil particles.
- Deposition: When the water slows down, the soil particles are deposited.
DOM
- dead organic matter
- from biotic elements
Good agricultural soils (structure)
allow for:
- plant root growth
- nutrient retention
- free air and water movement.
They are described as:
- friable (crumbly) and break up easily.
- Poor soil structure has coarse lumps that do not break apart.
Type of farming & levels of food production depend on: (5)
- Environmental Conditions: Weather (precipitation, sunlight, temperature), topography, and soil conditions determine the suitability for specific crops or livestock.
- Access to Vehicles and Technology: Availability of tractors and animal feeding systems.
- Financial Resources: Funds for purchasing land, seeds, fertilizers, pesticides, equipment, and labor.
- Cultural and Environmental Values: Influence of traditional methods or modern technology based on community beliefs.
- Government and Political Initiatives: Education programs and financial incentives to encourage specific products or methods.
soil degradation definition
the decline in soil condition caused by its improper use or poor management
subsistence farming
farming in which nearly all of the crops or livestock raised are used to maintain the farmer and the farmer’s family, leaving little, if any, surplus for sale or trade
Reasons for hunger despite enough food porduced to feed everyone
- Poverty that prevents people being able to afford food.
- Poor infrastructure that limits access and distribution to food.
- Extreme weather events, such as drought or floods.
- War and associated displacement of people.
- Food waste. The FAO estimate that approximately a third of food produced is lost or wasted each year.
Food supply chain (5)
- harvesting
- processing and packaging
- distribution
- retailer
- consumer
main crops prefer a soil pH of:
between 5.5 and 7.5
Soil as a non-renewable resource
- rate of soil formation is slow, the FAO estimate that it takes around 1,000 years to develop up to 5cm of soil.
- ^varies considerably between places
- Soil formation is fastest under sunny, warm and wet conditions when there is maximum plant growth.
- ^contributes to high levels of plant litter and other dead organic matter which is broken down to form soil.
wind erosion
- Dry regions with exposed soil surfaces are most vulnerable.
- Particles that are light and loose (for instance, sand particles) are more easily picked up by wind currents.
- The wind velocity can increase along large flat areas, making large open areas more vulnerable
functions of soil
- Medium for plant growth. Soil supplies nutrients and water as well as anchors roots.
- Water storage and purification system.
- Habitat for organisms, such as bacteria, insects and mammals. These organisms modify the soil.
- modifies the atmosphere through respiration of the soil organisms and plant roots.
characteristics of souls will depend on
- Climate: Precipitation/evaporation determines the dominant direction of water movement.
- Organisms: Breaks down organic matter and mix it into the upper layers of the soil.
- Relief: The elevation, aspect of the slope (the direction it faces) and the angle of the slope.
- Parent material: The original material that the soil develops from. This can be either the bedrock or lake or glacial till that has been laid down on top of the bedrock.
- Time: Soil formation is a long and slow process, therefore it is considered to be a non-renewable natural capital.
soil leaching
the downward movement of dissolved mobile plant nutrients in the soil profile following percolating water such as rain or irrigation water
percolation
- the process by which water moves downward through the soil under gravitational forces.
- The rate of percolation depends on the water content and the hydraulic conductivity of the soil.
soil structure affects:
- aeration
- water-holding capacity
- drainage
- penetration by roots and seedlings
eating from lower trophic levels benefits
- yield of food per unit area from lower trophic levels is greater in quantity, lower in cost and may require fewer resources
- Not as much land, water, etc, raising grain to feed to animals.
- More people could receive an adequate diet
- Less fossil fuel energy (and associated emissions of CO2) would be required to produce our food.
categories of causes of inbalance in food distribution
- Ecological: some climate and soils are better for food production
- Economic: advance technology and money can overcome ecological limitation (transportation of water)
- Socio-political: underinvestment in rural area and rapid area in LEDC; poor human health weaken available labor force
increased sustainability in food consumption may be achieved through:
– altering human activity to reduce meat consumption and increase consumption of organically grown and locally produced terrestrial food products
– improving the accuracy of food labels to assist consumers in making informed food choices
– monitoring and control of the standards and practices of multinational and national food corporations by governmental and intergovernmental bodies
increased farming sustainability may be achieved through:
- organic farming
- polyculture instead of monoculture
- Using biodegradable pesticides
- Using pesticides that are target specific
food miles
- the distance food is transported from the time of its making until it reaches the consumer.
- one factor used when testing the environmental impact of food
desertification
- gradual land degradation of fertile land into arid desert
unsustainable agriculture
- total removal of crops after harvest leaves soil open to erosion
- excessive use of pesticides makes the soil toxic
- in many irrigation systems water evaporates before reaching the crops.
- Minerals dissolved in water remain on top soils causing salinization
- monocultures deplete soil nutrients
animal husbandry
area of agriculture that involves the breeding and care of farm animals
