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11 AGS Unit 2
11 AGS Unit 2 - Renewable Resources and Soils
| Term | Definition |
|---|---|
| recall and describe the cycling of nutrients | Water – ocean, atmosphere, precipitation, run-off, condensation, evaporation, transpiration N – atmosphere, soil, denitrification, mineralisation, leaching, fixation, nitrification, C – ocean, fossil fuels – respiration, photosynthesis, decomposition, |
| identify and describe renewable resources | a resource that can be replaced naturally over a relatively short period of time including water, edible biota, biofuels and forestry products |
| Define edible biota | organisms found naturally in a geographic region that can be used for human consumption. Examples finger lime, lemon myrtle, fish, witchetty grubs, native fruit and nuts |
| recall some of the key terms from the nitrogen cycle and what they mean | fixation - changing unavailable form of N to an available form; assimilation - protein production and tissue growth; ammonification - the creation of ammonia; nitrification - the conversion of nitrogen to nitrates or nitrites (available forms) |
| recall some of the key terms from the carbon cycle and what they mean | decomposition - breaking down; combustion - burning of fossil fuels; sedimentation - settling of carbon to the ocean floor; sinks - storage of carbon e.g. ocean |
| describe two ways by which Nitrogen is added to the atmosphere | Burning fuels causes nitrogen oxides to be released Fertilisers, necessary for increasing yield to feed the growing population, can be washed into waterways causing a rapid growth of microscopic algae. |
| Define renewable resources | a resource that can be replaced naturally over a relatively short period of time. examples are fresh water, edible biota, biofuels and forestry production |
| Define non-renewable resources | non-living resources that are not renewed quickly eg coal, oil, uranium |
| Describe biofuels | renewable resources produced from grain, sugar, vegetable oils, algae and green waste. The production process is considered “greenhouse gas neutral” as carbon dioxide produced during combustion is used up by the next crop. |
| List some disadvantages of biofuels | Large areas of farmland are needed for growing suitable biofuel crops Carbon dioxide is produced in preparing the land, and in the fermentation and distillation processes |
| Describe forestry products | Renewable resources that come from timber and forestry plantations. Timber doesn’t require a lot of energy to turn it into a useable product. Timber is also very recyclable |
| Identify two harvestable resources relevant to Australia that are important agricultural industries | water, edible biota, biofuels and forestry products |
| Describe harvestable resources | Useful products that humans can extract directly or indirectly from a natural ecosystem e.g. Water, edible biota, biofuels and forestry products or Food (seafood and game), wild foods and spices, Construction materials (wood), Natural fibres |
| Define ecosystem regulating services | the benefits obtained from the regulation of ecosystem processes such as climate and natural hazard regulation, water and waste management and pollination and pest control |
| recall some examples of ecosystem regulating services | Carbon sequestration and climate regulation Maintaining hydrological cycles Waste decomposition and detoxification Purification of water and air Crop pollination Pest and disease control Generating and maintaining soils |
| describe carbon sequestration | A natural or artificial process by which carbon dioxide is removed from the atmosphere and held in solid or liquid form. e.g. CCS or photosynthesis |
| describe the process of CCS | an artificial method to capture and store carbon. This can be injected underground and some oil wells pump carbon dioxide down wells to force oil to the surface |
| describe how deforestation is affecting climate control | Deforestation has caused a change in rainfall patterns and distribution. Resutls = increased temperature, decreased rainfall. Loss of trees can cause land use changes, the degradation of freshwater systems, loss of valuable soils, increased erosion, |
| describe how urganisation is affecting climate control | natural forests and grasslands are becoming covered with hard surfaces - roads, roofs, parking lots, etc The natural heat absorbing landscape is being replaced with a heat radiating artificial one |
| describe some examples of ecosystem supporting services | Natural processes in water catchment areas clean water to use for livestock and growing crops Bees, butterflies and birds pollinate plants for fruit and grain production Nutrient dispersal and cycling (carbon, nitrogen, etc). Soil formation |
| Explain how agricultural industries can be managed, through consideration of legislative requirements to reduce their impact on other ecosystems | Examples include: aesthetics, air quality, biodiversity and effluent management, |
| Describe sustainability | development that meets the needs of the present without compromising the ability of future generations to meet their needs |
| recall the pillars of sustainability | Economic, Environmental and Social |
| recall the trend of global meat consumption | Global meat consumption is increasing, particularly in developing countries |
| recall the trend of the sustainability of fish stocks | consumption of fish and seafood is increasing with the majority of marine fish stocks fully fished or overfished - resulting in an increase in aquaculture production |
| recall the trend of food consumption | demand for food is increasing annually as food consumption is increasing per capita and the world population is also increasing |
| Describe traditional Aboriginal methods and Torres Strait Islander methods of sustainable harvesting and management of Australian biota | for example: The practice of burning vegetation encouraged new growth as the fires were low intensity and attracted animals into the area to feed on regrowth. Minerals were released into the soil from the burnt vegetation and maintain soil fertility. |
| describe some examples of sustainable farming practices | Efficient irrigation to avoid problems such as soil salinity, optimal use of fertiliser application in relation to soil mineral analysis and use of wildlife corridors to conserve native wildlife. |
| describe how provisioning of dams impacts sustainability | Dams collect run off water within a catchment and store it for use for agricultural, urban and industrial needs Dams provide a safe, secure and cost effective water supply, as well as help mitigate floods |
| describe how urbanisation impacts sustainability | The expansion of urban areas has resulted in marked alterations to natural processes, environmental quality and natural resource consumption. The urban landscape influences infiltration (less soil available) and transpiration (less water available). |
| describe how resource extraction impacts sustainability | Pollution of waterways through metal waste Damage to waterways ecological systems Changing paths of waterways Redistributing groundwater |
| describe some of the reasons for water pollution | 1. added organic materials 2. Pathogens 3. Synthetic organic compounds (human manufactured compounds) 4. Nutrients 5. Pesticides, herbicides 6. Radioactive substances |
| describe some of the natural process that cause water pollution | Salinity. Blue-green algae. Flooding Blackwater. Acidic soils. Siltation. Drought |
| recall some examples of water use efficiency measures on farm | Minimum tillage or zero tillage Plant into stubble from previous crop Plant varieties suitable to climate Increase irrigation efficiency. Alternate water supplies e.g. groundwater or building dams |
| explain how government policy influences the availability and quality of fresh water | water buybacks - governments are purchasing water allocations from farmers to contribute to the 'environmental flow' of water in the Murray Darling |
| describe the condition of Australian soils | old, nutrient poor, geologically stable and structurally unstable. six per cent of the Australian landmass is arable. highly dependent upon vegetation cover to generate nutrients and for stability. |
| describe a typical soil profile | includes the O, A, B, C and D horizons |
| recall some of the biological properties of soil | organic matter, invertebrates and humus |
| recall some of the physical properties of soil | soil texture, soil structure, porosity, infiltration, water holding capacity, compaction |
| recall some of the chemical properties of soil | pH, cation exchange capacity, nutrient levels and nutrient availability |
| describe the O Horizon of a soil | leaf litter and organic matter |
| describe the A Horizon of a soil | the upper layer of soil, nearest the surface. It is commonly known as topsoil. It is often rich in organic matter. |
| describe the B Horizon of a soil | less fertile than Horizon A. There is less leaf litter and also less humus. The elements present are due to leaching from the upper horizons of the soil profile. |
| describe the C Horizon of a soil | large rocks and weathered material. Not particularly fertile. Little organic material or life. |
| describe the C Horizon (can sometimes be known as 'R') of a soil | the parent material or bedrock (unweathered) |
| describe the common components of a soil | ■45% Mineral Matter (from rocks) ■5% Organic Matter (dead & living plant/animal material) ■25% Air ■25% Water this fluctuates depending on rainfall, irrigation, evaporation etc. |
| describe the common soil particles in a soil | Gravel >2mm Sand 0.02 - 2mm Silt 0.002 to 0.02 mm Clay - less than 0.002 mm Soil particles are classified according to their diameter. |
| describe the characteristics of a sandy soil | particles have very little charge and therefore has weak bonds to ions. Therefore limited ability to hold nutrients or water. |
| describe the characteristics of a silty soil | Ideal particle size with good ability to hold and store nutrients. |
| describe the characteristics of a clay soil | A very small particle that has strong bonding ability. Surfaces have a negative charge so stores nutrients very well (may not readily give up). Cements soil together. Holds water well (can become waterlogged). Lacks airspaces |
| describe the characteristics of a loam soil | The ideal combination of sand, silt and clay so that the soil holds nutrients and water yet drains well so isn't easily waterlogged. The soil will also have adequate air spaces for plant roots and soil microorganisms. |
| describe soil texture | Refers to the size of soil particles in a soil (sand, silt and clay) Soil can be classified according to its texture class. Determined by a texture triangle or field determination (by feel). |
| describe the use of a soil texture triangle. | Water is added to the soil and allowed to settle out overnight. The depth of the sand, silt and clay are measured and converted to a percentage. The soil texture triangle is used to classify the texture class. |
| explain why soil texture is important | Important because it influences a) the amount of water the soil can hold. b) the rate of water flow through the soil (drainage). c) aeration and therefore workability of the soil. d) fertility. |
| describe soil structure | Soil structure refers to the way soil particles group together to form aggregates (or peds). Examples of soil structure include blocky, columnar, massive, platy, granular. A well-structured soil breaks up easily into peds (such as granular or blocky) |
| describe some agricultural actions that can negatively affect soil structure | Compaction Plough pans (caused by disc ploughs) Crusts (caused by rain on exposed soil) Conventional cultivation |
| describe some agricultural actions that can reduce soil structure degradation | zero or minimum till planting controlled tracks/precision agriculture |
| describe porosity in soil | a measure of the space between soil particles |
| describe infiltration in soil | the downward entry of water into the soil. The velocity at which water enters the soil is the infiltration rate. It is an indicator of the soil’s ability to allow water movement into and through the soil profile. |
| describe Water Holding Capacity in soil | the total amount of water a soil can hold at field capacity. Sandy soils tend to have low water storage capacity. |
| describe how Field Capacity is calculated | A soil is saturated (e.g. irrigation), then allowed to drain for 24 - 48 hours. The remaining water is considered the FC of the soil. |
| define Field Capacity | approximates the amount of water that is held in soil after it has been fully wetted and all gravitational water has been drained away 1 - 2 days after saturation. |
| define the Permanent Wilting Point (PWP) | the level of soil moisture at which a plant wilts and can no longer recover its turgidity. Soil at PWP will be dusty and dry. |
| define Available Water Content (A.W.C.) | The amount of water held between F.C. and P.W.P. it is a measure of the amount of water in the soil that is “potentially” available to plants. |
| describe some management techniques to conserve soil moisture | Maintain organic matter eg. Minimum tillage, manures. Crop rotation (different root lengths). Mulches (natural or artificial eg. Plastic). |
| define compaction | the process by which the porosity of a given form of sediment is decreased as a result of its mineral grains being squeezed together by the weight of overlying sediment or by mechanical means (e.g. tractors or vehicles) |
| describe why salinity is a problem in agriculture | high levels of salt in the soil mean that plants are unable to grow to their full potential. Salinity can be caused through the clearing of trees and irrigation with saline water. |
| describe why erosion is a problem in agriculture | if topsoil (A Horizon) is removed from the paddock, nutrients and water are unable to be retained. It can be caused by wind or water. |
| recall the best pH of soils for growth of plants | The best pH for plant growth is between 6 and 7. A highly acidic soil can be as low as 3 and a highly alkaline soil close to 10. |
| describe the agricultural practices that can raise pH (make it more alkaline) | the combined use of organic matter and the addition of calcium ions in the form of dolomite (calcium magnesium carbonate) or lime (calcium carbonate, oxide or hydroxide). |
| describe the agricultural practices that can lower pH (make it more acidic) | by adding organic matter as compost, green manures, and animal manures, without including lime or dolomite. Organic matter produces hydrogen ions as it decomposes. |
| describe the Cation-exchange Capacity (CEC) of a soil | the degree to which a soil can adsorb and exchange cations at a given pH (degree of fertility). Cations are positively charged mineral ions (NH4+, K+, Ca2+, Fe2+, etc...) Soil particles and organic matter have negative charges on their surfaces. |
| describe how to improve (increase) CEC of a soil | 1. increase the amount of clay 2. increase the amount of organic matter 3. increase in soil pH |
| describe how soil microbes promote soil formation | decomposing organic matter nitrogen fixation, ammonisation and nitrification oxidation reactions mineralisation reactions (breaking down soil into minerals) humus formation |
| describe some of the functions of humus in soil | binds soil particles into aggregates improving soil structural stability. Enhances water holding capacity of soil. Provides resilience against pH change. Moderates changes in soil temperature. |
| describe how land can be classified | via biological, chemical or physical properties, by the Australian Soil Classification system, by land suitability, land capability or agricultural land classification. |
| describe the land suitability categories | a 5-class system which is assessed from detailed mapping. There are three classes of suitable land (negligible limitations, minor limitations and moderate limitations), marginal land and unsuitable land. |
| describe the land capability categories | the assessment of land for broad land uses. It is an 8-class system assessed from broad scale mapping. Lower-numbered classes are suited to more intense uses and higher-numbered classes are suited only to low-intensity rural use or conservation etc. |
| describe Agricultural land Classification | based on the suitability of land for specified agricultural uses. It rates the ability of land to maintain a sustainable level of productivity. |
Created by:
DrLeeAGS
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