AGR2301 Flashcards
What are the 5 principles of sustainable farming?
- Farm productivity is sustained or enhanced over the long term
- Adverse impacts on the natural resource base of agriculture and associated ecosystems are minimised or avoided.
- Residues resulting from use of chemicals are minimised
- Net social benefit from agriculture is maximised
- Farming systems are sufficiently flexible to manage risks associated with the vagaries of climate and markets.
What are the 4 forms of water / soil erosion?
- Sheet erosion - where soil is lost along slope due to uniform flow of runoff
- Rill erosion - soil is lost by runoff concentrated in shallow channels
- Gully erosion - lost by runoff with rill wall collapse in deep channels (due to soil type, management, catchment characteristics, slope, land use, etc.)
- Soil is lost in tunnels with lateral flow of water
What are environmental rhythms?
- Circadian rhythms controlling plant function (e.g. photosynthesis, auxin production, etc.)
- Rhythms are generally believed to be controlled by a “biological clock”.
- Periods may range from 21-27 hours, but synchronised with environment by temperature and light / dark cycles.
- Temperature - affects dormancy in seeds, flowering and fruiting
- Photoperiod - differences in the relative light / dark period. Affects flowering and initiates dormancy.
What are the 16 nutrients essential for plants?
C, H, O, N, P, K. Ca, Mg & Sulphur are macro (large amount needed) nutrients.
Fe, Mn, B, Cu, Zn, Cl & Mo are micro (needed in small amounts)
- EDIT?* What do plants require to survive?
- Air, sunlight and water for photosynthesis
- Nutrients (N, P and K from soil) - should be slightly acidic-neutral
- Weed removal
- Pest & disease control (staking, crop rotation, removal of diseased plants, etc.)
- Drainage - ensure water doesn’t build up
Disease develops in the presence of:
- Susceptible host
- Pathogenic source
- Favourable environment
What are the major types of diseases?
- Parasitic diseases: internal parasitic (liver fluke, worms, etc.) and external parasitic (tropical (i.e. cattle tick, buffalo fly, etc) and blow flies, mange (in pigs), lice (in sheep).
- Metabolic disorder - aka nutritional disorder; white-muscle disease, selenium deficiency
- Miscellaneous disease - degenerative conditions
- Non-infectious (disorder) - exposure to pollutants / toxicity (i.e. pesticide) or exposure to extreme environmental conditions (hailstone, extreme heat or cold, cyclones, etc.)
What are the 4 classes of acquired immunity?
- Passive immunity - no previous exposure to antigen, i.e. colostrum.
- Active immunity - exposure to antigen, activates immune system, acquired over weeks.
- Vaccination - phased introduction of specific pathogen antigen to develop immunity
- Resistance - age, physiology, nutrition, stress level, etc.
What are the 4 main ways plants develop infectious disease?
- In presence of susceptible host, pathogenic source, favourable environment
- Initiation of infection with inoculum (vaccine)
- Pathogen-host transfer of inoculum (vaccine)
- Nature of infection (localised or systemic; sub-clinical (no sign of symptom AND environmental factors affecting spread of disease).
What are plant disease vectors and what do they do?
A biting insect that spreads disease from one plant (or animal) to another - through probing and ingestion (saliva)
What are 5 pest control measures?
- Exclusion - preventing entry of a pest into an area
- Eradication - complete elimination of pest within small areas (exotic species with limited control)
- Agronomic or Cultural control - modification of environment to make it unfavourable to pest survival (sanitation, tillage, rotation, etc.).
- Chemical control - using chemicals to kill target pests (e.g. herbicides, insecticides, fungicides, etc.)
- Biological control - natural enemies managed to reduce pest survival (microbes, parasites, predators of pest species augmented or introduced)
What are the 5 key components of integrated pest management?
- Understand key factors that regulate pest numbers
- Establish damage thresholds and economic thresholds for each key pest
- Monitor pest numbers and their natural enemies
- Monitor environmental and crop conditions to predict when damaging pest outbreak is likely
- Select a pest intervention strategy that will minimise damage to non-target organisms.
What are the 4 main environmental constraints to crop production?
1) Temperature / weather
2) Sunlight
3) Water
4) Soil / nutrients
All of these can be referred to as “land capability”
What is meant by the term ‘Day Degrees’ or ‘Cumulative Degree Days’?
- The sum of the maximum temperatures above a limiting threshold (base) temperature for a given species required to complete a growth stage.
- Mean daily temperature can be used on occasion
Explain what the Law of the Least Limiting Factor means:
All nutrients should be provided in an equal and consistent manner. If for example, there are 8 crucial nutrients and you don’t provide just one of them at the optimal ratio, it is likely the plants will only be able to grow based on the 2 limiting nutrients.
i.e. if you don’t have enough nitrogen, it doesn’t matter how much of the other nutrients you have, the plant will only grow in accord with the nitrogen as the limiting factor.
What are the input factors affecting animal production (4 pillars of animal production)?
1) Genotype / breeding
2) Nutrition / feed
3) Disease / welfare / health management
4) Environmental management
(points 3 and 4 come under health / well-being)
What are the output factors affecting animal production?
1) Amount of output and price
2) Value
3) Quality
4) Timeliness of supply
What are some characteristics of monogastrics (non-ruminants)?
- 1x chambered gut
- Small intestine does most of the absorption
- Large intestine / cecum (facilitates microbial breakdown of undigested protein).
- Cellulose
- Lignin breakdown material (roughage)
What are some characteristics of ruminants?
- 4x chambered gut (Reticulum, Abomasum, Omasum, Rumen)
- Enzymic breakdown in reticulo-rumen
- Rumen muscle contractions draw solids back into oesophagus & liquids into omasum
- 70% of all digesta solubilised by microorganisms (cellulose, lignin) in reticulo-rumen
What are the energy processes in animal metabolism?
1) Catabolism - breakdown of food for energy
2) Anabolism - building up cells / tissues / organs from breakdown products
3) Oxygen (electron donor) - bound to haemoglobin in lung, transported in circulatory system (CO2 by-product)
4) Metabolic rate - in birds and mammals it is controlled by body temperature (homeotherms)
5) Metabolic rate - in insects and reptiles it is controlled by temperature of the environment (poikilotherms)
What are the 6 components of production value (proximate analysis) of animal feed components? (what are the food requirements supplying major functional requirements for animal growth?)
1) Moisture - water, volatile acids and bases
2) Ash - major & trace elements
3) Crude protein - nitrogen compounds
4) Ether extract - fats, oils, organic acid
5) Crude fibre - cellulose, lignin, hemicellulose
6) N-Free extractives - sugar, starch, pectins, organic acids
Explain the diagram for animal energy requirements (Module 6A, slide 31).
Gross energy (20-40% lost in faeces) --> Digestible energy (4% lost in urine, 6% lost in methane) --> Metabolisable energy (heat increment) --> Net energy (maintenance) --> Production (less than 20% left by time it reaches here)
What are the “5 freedoms” of animal welfare?
Freedom from:
1) Thirst, hunger and malnutrition
2) Discomfort
3) Pain, injury and disease
4) Fear and distress
5) Freedom to express normal behaviour
Where did the 5 freedoms originate? [check lecture, module 6B, slides 7-9]
Came about as recommendations from report prepared post WWII, finalised in 1979, adopted later
What does a good system of intensive livestock production involve? [check lecture 13, module 7A]
For pigs, it involves temp control, ventilation, feeding & drinking space, hygiene and freedom of movement.
Farmers require low-cost buildings, often automated in cleaning and feeding, that command high output and return on investment.
What is an input-output relationship?
The basic principle that in order to achieve and maximise output, there must be inputs (fertiliser, irrigation, pesticides, etc.).
Also important to note that if too much inputs are used, the output can stagnate or even decrease. This is referred to as the ‘Law of Diminishing returns’.q
What is the law of diminishing returns?
“A decrease in the amount of extra output per each additional unit of input”.
To apply to assignments, it might mean that in the first 8 hours we achieve 90% of our assignment. In the next 8 hours we might achieve 5% of our assignment, and so on. This amount generally diminishes and is often evident in fertiliser applications.
It is possible, due to the cost of additional fertilisers, to lose money if they are not effective or detrimental to the land / crop.
What are marginal changes, in the context of farm economics?
Marginal changes are the changes between profit rates with each input. When each profit / marginal change minimises / gets less with each added input, it may soon likely decrease with more input.
