Soil System
Identify the orizons of a soil profile
- O: Organic horizon (referred to as the O horizon) is on the top of the soil and includes all the DOM that accumulates on top of the soil.
- A: A horizon is the top soil or mineral layer. This layer is usually dark in colour due to the high proportion of organic matter.
- B: B horizon is the sub-soil and tends to be the zone of illuviation or accumulation. Minerals and particles are washed into this horizon from the ones above.
- C: C horizon is the decomposed parent material.
What type of soil is 20% clay, 45% silt, and 40% sand?
Loam
Describe two different subsistence farming systems.
Shifting agriculture
Slash and burn, clearing land by cutting and burning.
Land used for few years until soil becomes infertile
Overtime, trees will grow and soil will recover.
Nomadic herding
Moving of cattle in search of suitable grazing areas.
Intensive subsistence farming
Families farm on a plot of land and aim to produce enough food to feed their families with some surplus to sell. They often employ traditional farming methods that are labour intensive, such as terracing of paddy fields.
Identify factors that contribute to hunger around the world.
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.
Outline the reasons for increase in demand for meat.
Increase in population, more people means that there are more people to feed so more meat demand.
Increase in meat production, means cheap meat production which makes more people able to afford meat.
Status value of buying and eating meat within some cultures. For instance, in parts of Asia it can be prestigious to eat rare and expensive meat, demonstrating an individual's wealth and position in society.
Explain how soil can be viewed as a system.
Soil is not static; it is continually changing and developing through physical, chemical and biological processes such as weathering, erosion and translocation (internal reorganisation of matter and energy). As soil has processes it can be seen as a system.
Explain how soil texture impacts primary productivity.
Soil texture influences nutrient retention as finer texture soils tend to store soil nutrients. Coarse soils tend to be well drained and so are more prone to leaching and so lose the nutrients.
Explain reasons for differences in food production around the world.
Environmental conditions e.g. weather (precipitation, sunlight, temperature), topography and soil conditions that determine whether the area is suitable for growing specific plants or for rearing certain animals.
Access to vehicles and technology, such as tractors and animal feeding systems.
Available financial funds to purchase land and inputs, such as seeds, fertilizers, pesticides, equipment and labour.
Cultural and environmental value systems that influence methods of farming. For example some communities will use specific traditional methods of husbandry whereas other communities with technocentric beliefs will embrace the use of modern technology.
Government and political initiatives. For instance, farmers can be encouraged to produce certain products or employ particular methods through education programmes and financial incentives.
Explain the role of consumer choice on farming methods.
New technologies have risen which allow for an increase in variety of food in supermarkets around the world, which has allowed food to be available beyond their usual season. This contributes to more pollution due to the processing, packaging and transportation that the food requires.
Describe factors that influence sustainability of farming systems.
Legislation: can be used to restrict use of certain substances and set regulation standards for food production.
Pollution management: strategies to reduce pollution and its impacts by reducing pesticides, land management practices, and removing pollutants from the environment.
Reduction of food waste
Growing indigenous crops
Polyculture farming
Reduction in meat consumption
Outline the transfer of material in a soil profile.
Movement of materials through the soil profile. Transfering water and air from the upper layers downwards mostly by burrowing animals.
Explain how soil is an ecosystem.
An ecosystem must have biotic and abiotic components that interact. (Ecosystem is a community of interdependent organisms and the physical environment they interact with)
Soil has biotic factors: such as microorganisms and macroorganisms
Soil has abiotic factors: such as rocks and minerals
Thus it can be viewed as a system.
Discuss the environmental impacts of intensive commercial farming.
Pesticides kill non-target organisms and can reduce overall biodiversity, these can also bioaccumulate and biomagnify.
Fertilizers can result in nutrient run off, causing eutrophication.
Water abstraction 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.
Soil degradation, for example excessive irrigation, can increase nutrient run-off and also cause salinisation.
Loss of natural habitats, this also leads to loss of biodiversity.
Loss of pollinators such as bees as a consequence of using pesticides and habitat clearance.
Evaluate use of farmers markets.
Advantages
fresh and seasonal produce
reduced food miles
less refrigeration and use of preservatives
improved local economy
place of social interaction for the community
improved cohesion between farmers and consumers
Improved understanding of farming methods
Disadvantages
Higher cost to produce than commercial farming
Range of food is limited by seasonality
reduced shopping times when compared to supermarkets
may reduce global distribution of wealth
Describe properties of fertile soils.
It is rich in nutrients necessary for basic plant nourishment. This includes nitrogen, phosphorus and potassium.
It consists of adequate minerals such as boron, chlorine, cobalt, copper, iron, manganese, magnesium, molybdenum, sulphur and zinc. These minerals promote plant nutrition.
It contains soil organic matter that improves the structure of the soil. This enables the soil to retain more moisture.
The soil pH is in the range 6.0 to 6.8.
It has a good soil structure which results in well-drained soil.
Outline three of the soil system storages.
- Organic matter: DOM that comes from biotic elements of an ecosystems.
- Organisms: soil hosts millions of organisms, these add nutrients to the soil and also break down DOM.
- Minerals: parent material is made up of minerals, most from the parent material.
- Air: the amount of gasses present in the soil, this can depend on weather and type of soil.
- Water: it is dependent on soil texture.
- Nutrients: may be stored in the soil or in the organic matter.
Compare and contrast the properties of sand, clay and loam soils.
Sand is the largest of the mineral particles. Sand particles create large pore spaces that improve aeration. Water flows through the large pore spaces quickly. Soils with a high percentage of sand are generally well drained. Sandy soils lack the ability to hold nutrients and are not fertile. Sandy soils also feel gritty to the touch.
Silt is the mid-size soil particle. Silt has good water-holding ability and good fertility characteristics. It feels like flour when dry and smooth like velvet when moist.
Clay is the smallest size soil particle. Clay has the ability to hold both nutrients and water that can be used by plants. It creates very small pore spaces, resulting in poor aeration and poor water drainage. Clay forms hard clumps when dry and is sticky when wet.
Explain reasons for differences in food production around the world.
Intensive commercial farming
Monoculture
High yields
GMOs
herbicides/insecticides
fertilizers
usage of mechanical equipment
more sowing
Organic farming
Physical removal by hand
biological predators instead of pesticides
crop rotation
usage of manure and compost as fertilizers
Distinguish between the reasons for food waste in less economically developed countries and more economically developed countries.
In LEDCs food loss tends to be associated with stages from production to the market. This includes severe losses to pests, while food is in storage. The transportation infrastructure may also be poor and the lack of adequate refrigeration results in the loss of perishable produce before reaching the market place.
In MEDCs, food loss tends to be associated with consumer behaviour, together with food policies and regulations. Such as consumer misunderstanding of labels such as “best before date”.
Outline factors which contribute to desertification.
Overgrazing: Animal grazing is a huge problem for many areas that are starting to become desert biomes. If there are too many animals that are overgrazing in certain spots, it makes it difficult for the plants to grow back, which hurts the biome and makes it lose its former green glory.
Deforestation: When people are looking to move into an area, or they need trees in order to make houses and do other tasks, then they are contributing to the problems related to desertification. Without the plants (especially the trees) around, the rest of the biome cannot thrive.
Farming Practices: Some farmers do not know how to use the land effectively. They may essentially strip the land of everything that it has before moving on to another plot of land. By stripping the soil of its nutrients, desertification becomes more and more of a reality for the area that is being used for farming.
Urbanization and other types of land development. As mentioned above, development can cause people to go through and kill the plant life. It can also cause issues with the soil due to chemicals and other things that may harm the ground. As areas become more urbanized, there are less places for plants to grow, thus causing desertification.
Climate Change: Climate change plays a huge role in desertification. As the days get warmer and periods of drought become more frequent, desertification becomes more and more eminent. Unless climate change is slowed down, huge areas of land will become desert; some of those areas may even become uninhabitable as time goes on.
Stripping the land of resources. If an area of land has natural resources like natural gas, oil, or minerals, people will come in and mine it or take it out. This usually strips the soil of nutrients, which in turn kills the plant life, which in turn starts the process toward becoming a desert biome as time goes on.
Natural Disasters: There are some cases where the land gets damaged because of natural disasters, including drought. In those cases, there isn’t a lot that people can do except work to try and help rehabilitate the land after it has already been damaged by nature.
Outline the inputs and outputs of the soil system.
Inputs
Minerals: The minerals of a soil come from the weathering of the parent material.
Organic matter: Organic matter comes from the living organisms that are on and in the soil.
Gases: Certain plants also add some inputs to the soil. Certain plants fix atmospheric nitrogen and change it into nitrates and ammonia compounds in the soil.
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.
Outputs
Soils lose minerals, organic matter, water and gases through the action of wind, water and plants and animals. Wind can physically remove soil by blowing loose soil away. Water leaches minerals from the soil, and washes the finer clay particles out of the soil.
Explain the impact soil texture has on mineral and nutrient content, drainage, water-holding capacity, air spaces, biota and potential to hold organic matter.
Soil structure affects aeration, water-holding capacity, drainage, and penetration by roots and seedlings, among other things. Soil structure refers to the arrangement of soil particles into aggregates (or peds) and the distribution of pores in between. It is not a stable property and is greatly influenced by soil management practices.
Justify whether the increase in demand for meat is sustainable.
The increase of food demand is not sustainable because there is not more space to produce more animals. Meat consumption climbing steeply as the world population increases along with average individual income, and could play a significant role in increasing carbon emissions and reducing biodiversity. Livestock farming is also a major contributor to biodiversity loss, as forests and wild countryside are given over to agricultural land to grow animal feed.
Evaluate organic farming methods.
Organic farming is more labour intensive than intensive commercial farming and produces lower yields. Hence the cost of organically produced crops tends to be higher, which has led to accusations of organic food being elitist and not readily accessible to all. Despite this, the global organic market is growing especially in affluent countries within Europe and North America. It is driven by concerns over health, concerns over ethics, and increase in awareness of unsustainable farming methods.
Explain why soil is considered to be a non-renewable resource.
Soil is a non-renewable resource. Its preservation is essential for food security and our sustainable future. Soil is a finite resource, meaning its loss and degradation is not recoverable within a human lifespan. As a core component of land resources, agricultural development and ecological sustainability, it is the basis for food, feed, fuel and fibre production and for many critical ecosystem services.