Please enable JavaScript.
Coggle requires JavaScript to display documents.
5.3: Soil Degradation and Conservation - Coggle Diagram
5.3: Soil Degradation and Conservation
Fertile soil requires significant time to develop through the process of sucession
Human activities may reduce soil fertility and increase soil erosion
Soil conservation strategies exist and may be used to preserve soil fertility and reduce soil erosion
Understanding
1) Soil ecosystems change through sucession. Fertile soil contains a community of organisms that work to maintain functioning nutrient cycles and that are resistant to soil erosion
Q1) Explain relationship between soil ecosystem sucession and soil feritility
Influence biotic factors range form orgnism or barriers to humans -bacteria fix atmospheric nitrogen converting to usable form of plant roots -mycorrhizal fungi on tree roots take up soil nutrients and pass them directly to the tree -decomposers break down litter releasing nutrients into the soil -soil organisms help to mix the soil improving its structure -animal burrows help to aerate the soil -animal faeces return nutrient to the soil.
Indirect influence -interception of precipitation by vegetation -reduction of precipitation via evapotranspiration
2) Human activities that can reduce soil fertility include deforestation, intensive grazing, urbanization and certain agricultural practices (such as irrigation and monoculture)
:
3) Commercial, industrialized food production systems generally tend to reduce soil fertility more than small-scale subsistence farming methods.
Q1) Discuss the influences of human activities on soil fertility and soil erosion.
Overgrazing:- the grazing of natural pastures at stocking intensities above the livestock carrying capacity. Main impacts: 1. Greater the intensity of grazing → the more vegetation covers is removed. 2. Large herds may destroy vegetation cover by trampling. - Reduce interception, Increases raindrop impact impact - Increases soil erosion 3. Grazers may compact the soil • Increases soil compaction, less infiltration – soil become impermeable • Increases potential for soil erosion • Semi arid area:- lead to desertification
• Irrigation :- increase amount of salt in soil (ground water level are close to the surface) • Evaporation:- capillary action bring water to the surface, evaporated and leaving soluble salt behind (salinization). • Paddy field / large dams→ as water evaporate, salinity increases • Coastal and estuarine:- salt water intrusion
Commercial system / intensive agriculture • Deforestation:- leave the soil bare →contributing to soil erosion • Lead to soil exhaustion:- growing the same crops reduce availability of certain set of nutrients. • Tillage/ploughing can leave the soil prone to erosion • Lost of nutrients replace by chemical and organic fertilizer require cost • Use of pesticides → leading to soil toxification
COMMERCIAL, INDUSTRIALIZED FPS • Large amount of chemical and energy input is required in commercial and industrialized food production systems. • Usually alters the natural environment /deforestation, deteriorates soil quality, and eliminates biodiversity → Maximize the potential yield of crops. • The use of heavy machine compact the soil→ more impermeable → reduce O2 content. • The use of fertilizer alter soil’s chemical composition + increase nutrient runoff • The use of pesticides / herbicides → increase amount of dangerous toxins
4) Reduced soil fertility may result in soil erosion, toxification,salinization and desertification
Wind erosion
Gullying
Sheet Wash
Soil erosion
Salinization
Desertification
5) Soil conservation measures include soil conditioners (such as organic materials and lime), wind reduction techniques (wind breaks,shelterbelts), cultivation techniques (terracing, contour ploughing,strip cultivation) and avoiding the use of marginal lands.
Soil Degradation
Usually the result of -erosion by water and wind -physical degradation -chemical degradation -biological degradation -climate and land use change may accelerate above factors
Physical degradation
• loss of structure, soil crusting, surface sealing and compaction
• Caused by compaction through heavy machine or animal and cultivation in wet weather.
• Soil crusting and compaction:- increase runoff, decrease the infiltration of water into the soil, inhibit plant growth and leave the surface bare.
Factors influencing the erosion of soil by water and wind
Chemical Degradation
• Loss of nutrients or organic matter:- reduce the capacity of soils to support plant growth and crops production
• Soil acidification:- results from change in the composition of soil ( impact of acid rain /dry deposition of acid gasses and particles, combustion of fossil fuels)
• Salinization: accumulation of salts rise which impedes the entry of water in plants roots (arid and semi arid areas) : evaporation associates with irrigation : coastal zones:- capillary action bring salt to the upper part of soils.
• Soil toxicity:- caused by municipal and industrial waste, oil spills, excessive use of fertilizer, herbicides and insecticides or release of radioactive materials and by airborne pollutants
Biological degradation
Biological degradation: loss of organic matter and biodiversity
• Organic matter enters soil mainly from plants remains and organic manure
• loss of organic matter reduce the ability of soil aggregate (impact of rainfall), result the formation of soil crust, reduce water infiltration, increase run off and water erosion
