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Agroecosystems - Coggle Diagram
Agroecosystems
How the properties of pesticides influence their effectiveness and environmental impacts:
Solubility in water/lipids: Pesticides that are water soluble are more likely to be washed off and need re-application. Liposoluble pesticides may be absorbed and stored within a crop, possibly entering the human food chain
Mode of action: There are two main modes of action by which chemical pesticides kill pests
Persistence: Chemically more stable and degrade slowly. This reduces frequency of re-application
1) Contact action: Kills plants by damaging the tissues they are sprayed onto. Contact insecticides kill insects that are sprayed directly
Specificity: A measure of the range of taxa affected by the pesticide
2) Systematic action: Are absorbed by the crop and translocated throughout the plant. This protects the plant and will also protect new growth. The pesticide cannot be washed off.
Toxicity: Pesticides which have high toxicity require the use of smaller volumes. Most pesticides act by inhibiting enzyme action
The importance of pollinators and how they can be encouraged: Many crops are pollinated by species such as bees, moths, beetles, and other taxa. Their services can be aided in different ways
Provision of food supplies by growing plants that provide nectar
-restricting the use of pesticides that harm pollinators
The reasons why antibiotics are used:
1) to treat infections: A course antibiotics may be kill the pathogenic bacteria
2)To prevent infection: regular large doses of antibiotics may prevent livestock from becoming infected with pathogenic bacteria
3) To promote growth:Can be used to increase growth rate efficency
Abiotic factors that affect productivity and how they are controlled
Technological factors
3) Water:Importance
-physiological functions: Water is the general physiological solvent in living cells.
Nutrient absorption: Nutrients are absorbed from soils as ions dissolved by water
-Gaseous exchange
How water supply effects crops:
Amount
Reliability
Quality
problems caused by waterlogged soils: Higher risk of fungal diseases
and
Soils become anaerobic
Methods to reduce soil water levels: excavation of drainage ditches or instillation of drainage pipes and deep ploughing
Problems caused by water shortages
:2) Light
The intensity of light affects the rate of photosynthesis, brighter light producing more photosynthesis.
-Photoperiodism (daylength) affects the growth and development of crops. Some plants require longer periods of light each day for flowering, for example, oats, while others require shorter days,for example,maize. Day length can affect the reproduction function of some livestock species
-Long day length increases milk production
Control of light:
Artificial lighting can be used to extend the growing season, for example, for salad crops in greenhouses
Suitability of the environment: 1)Temperature can affect different species
-Length of the thermal growing season: It is not just necessary for temperatures to be warm enough for growth. For example, Grass can survive in very low temperatures but can't grow at temperatures below 5 degrees
-Frost-free period: Some crops are damaged by frost, for example, maize, so it cannot be grown in areas where late frost is likely. The blossom of many fruit crops is damaged by frost.
-Impact on evaporation: Higher temperatures increase the rate of evapotranspiration which increases crop water requirement
-Biochemical reactions: The rate of biochemical reactions, including those involved in photosynthesis and plant growth, are generally increased by higher temperatures.
-Thermoregulation: Mammals and birds use food energy to maintain constant internal body temperature. Keeping the animals warm reduces heat loss and increases the amount of food energy to put into growth
Control of temperature: The selected field location can affect the temperature
Low lying areas such as valley bottoms are more likely to have frost as cold dense air collects there
4) Soil nutrients: plants need a range of nutrients for growth and good health
Soil salinity:Essential for plant growth as they include soil nutrients nut excessive salinity can kill plants by osmotic dehydration
6) Soil PH:
Biotic factors that affect productivity
Crop rotation: Different pests have their own unique pest species. If the same crop is grown year on year it's likely to increase each year
Companion crops: These are crops which, if grown together,will be more productive
Pest control: Pest are organisms that reduce agricultural productivity. They may:
-Be predators that eat crop or livestock
Compete for resources
Predator habitats: The populations of natural pest predators can be increased by providing suitable habitats
Biological control:Predator or pathogens may be introduced to control pests
Sterile male techniques and pheromone traps
Genetic resistance to disease: Selective breeding may enhance the resistance to a variety of pests or diseases