| 7. VOCABULARY / GLOSSARY |
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BIO-MASS: Bio-mass is the total matter on and in a property which has to do with the productive process. It consists of everything which forms a base for growth or production. Generally speaking, the amount of bio-mass determines the amount of food the land can produce, whether in the form of crops or stock. The Bio-mass is made up of several components which include:-
CONVERGENCE: When low-level airstreams meet, or converge, they generate uplift, as in the Intertropical Convergence Zone. Convergence can occur near ‘inland heat lows’ or troughs over northern Australia. Easterly trade winds, deflected southward by the trough, meet dry southerly winds on the western side, often forming thunderstorms. Other examples are orographically-induced convergence, and ‘seabreeze convergence’, a common source of thunderstorms in tropical coastal areas.
CONVECTIVE UPLIFTING: Thermal currents over an area of hot land (or very warm water) can produce cumulus clouds, with showers if sufficinet moisture is present. If the airmass is unstable and the thermal currents strong, the cumulus may develop into cumulonimbus - the thunderstorm cloud.
Cumulonimbus produces lightning and thunder, usually with strong wind gusts, heavy rian and sometimes hail. However, as individual thunderstorm cells are usually small, strom rain is localised and highly variable. Occasionally in the tropics, thunderstorms amalgamate into intense clusters to produce several hours of heavy rainfall over an extensive area.
Apart from the broadscale uplift processes associated with, for example, fronts and depressions an airmass can be lifted by:
If the airmass is unstable, it will introduce thermals, or convective currents, forming shower or thunder clouds; if stable, it forms more widespread stratiform cloud and steady rain or drizzle.
Convective rainfall is almost always assisted by some other source of uplift-convergence, orographic lifting, or fronts or depressions. It is best developed in the warmer months, and accounts for much of the rainfall in northern and central Australia, but for relatively little in the southern states.
DROUGHT: Drought can have a variety of meanings. For meteorologists, severe and serious droughts refer to the 5 and 10 percentiles respectively in the probability distribution of rainfall events. Plant physiologists understand it to mean the point at which plants lose turgor. Ecologists see drought as a condition where there is a qualitative change in plant growth or survival. Soil hydrologists include soil moisture status, the amount of run-off, the effects of soil type as well as the actual rainfall.
Primary producers generally refer to drought when the available rainfall over a period of time is insufficient to generate adequate plant growth and there is a consequent reduction in agricultural production.
Even within some agricultural industries, there can be differences of emphasis; references to a "feed" drought, "protein" drought and "water" drought are common in the livestock sector.1
EL NIŅO: Traditionally, El Niņo was the name given to warming of coastal waters off Peru around Christmas. Occasionally, this warming is exceptionally strong. It is these occasional extremes (once every 5 to 9 years) that are now called El Niņo episodes. This strong warming of the eastern Pacific is linked to negative phases of the Southern Oscillation. Through this connection, El Niņo episodes are generally periods of drought over eastern Australia.2
FRONTAL SYSTEMS AND DEPRESSIONS: Frontal lifting occurs when airmasses of different density and temperature are brought together. In a cold front, a relatively cold, dense, often fast moving airmass undercuts a lighter, warmer airmass. The sudden lifting creates large cumulus clouds, resulting in showers and sometimes thunder storms. Most fronts affecting southern Australia are cold fronts.
Rainfall may be more widespread, and often heavy, if the airmass ahead of the front is fairly moist, as in a tropical-extratropical interaction.
Very occasionally, a warm airmass overruns a cold airmass (a warm front), giving a more gradual uplift and steady rian; more often widespread steady rain is produced by uplift associated with upper atmospheric temperature gradients (see section on northwest cloudbands).
Cold fronts are frequently followed by cold winds from the west or south-west, with showers in the southern states. Much of the rain experienced in exposed or hilly areas, and most of the snow on the Southern Highlands, falls from cold fronts and post-frontal airstreams.
Low pressure areas - lows or depression - may or may not be associated with frontal systems. Depressions may orginate within the mid-latitude westerlies to affect the southern states, or within the monsoonal trough in summer over northern or central Australia. Depressions azre generally accompanied by rain, sometimes by thunderstorms; the rain can be very heavy if the ‘low’ is slow-moving, and associated with moist air. This often occurs off eastern Australia, where slow-moving, intense, ‘east coast lows’ can produce flood rains and gales, as in the record flood in Sydney in August 1986.
LA NIŅA: The opposite of El Niņo, when the waters in the eastern equatorial Pacific are abnormally cold, dubbed La Niņa. La Niņa episodes (positive phases of the Southern Oscillation) are characterised by more frequent and heavier rain periods, occasionally with severe flooding.2
OFF FARM INCOME: Income produced outside the farm business which provides cash flow.
OFF FARM INVESTMENT: Capital that is invested outside of the farm business.
PROPERTY MANAGEMENT PLANNING (PMP): Strategic planning approach to property management. It focuses on land-holders reviewing current management practices and developing long term sustainable management strategies for their properties.
It is planning which incorporates reviewing and developing land-holders' personal goals; natural resource assessment and planning and physical planning; sustainable agricultural production; business and financial management; ecological considerations; drought preparedness and risk management; and marketing.
PROPERTY PLAN: Plan with aims to provide to the land-holder or land occupier, recommendations for the management of an entire farm based on two main principles:
(i) land capability assessment;
(ii) the need to protect the land from the effects of soil erosion, loss of fertility and the consequent loss in production capacity.
RAINFALL PROBABILITY: The likely occurrence of a (designated) rainfall event to occur within a certain time, eg a 60% chance of 40mm of rain to fall in a month. There is expected 40mm of rain to occur that month in 6 out of 10 times.
RESOURCE INVENTORY: It is a listing of vegetation species, soil units and rainfall data in a property plan.
The resource inventory is used to provide basic information for developing the land management recommendations for the property.
RETURN TO TOTAL CAPITAL: The annual operating profit expressed as a percentage of total capital. Measures the efficiency of resource use.
RISK ASSESSMENT: Assessing the risk (i.e. the uncertainty in the outcome) of any project, including production, climate, market, financial and personal risks. Often a budget is helpful to assess the impact of poor seasons and low prices on your ability to service a loan.
RISK MANAGEMENT: Acknowledging and determining appropriate options to manage for risks in any project including production, climate, market, financial and personal risks.
SOIL DEGRADATION: Decline in soil quality commonly caused through its improper use by humans. Soil degradation includes physical, chemical and/or biological deterioration. Examples are loss of organic matter, decline in soil fertility, decline in structural condition, erosion, adverse changes in salinity, acidity or alkalinity and the effects of toxic chemicals, pollutants or excessive flooding.3
SOUTHERN OSCILLATION: The major air pressure shift between Asia and the eastern Pacific regions. Related changes occur in the trade winds, in cloudiness patterns and in rainfall across the Tropical Pacific. The new approach to seasonal outlooks is based on Southern Oscillation relationships. The Southern Oscillation is measured by an index of pressure difference between Tahiti and Darwin.
When the index is positive, the trade winds blow strongly across the Pacific, feeding moisture into the monsoons of Asia and Australia.
When the index is negative, trade winds are weak or even reversed. The monsoons are deprived of their energy source and rainfall is much below average over the Australian/Asian region.2
SUSTAINABILITY: The ability to remain viable. When considering sustainability it is useful to consider the following:
Agronomic - the ability of the field system to maintain acceptable levels of production over a long period of time (this must be evaluated over multiple growing seasons).4i
Microeconomic - the ability of the farm unit to maintain economic viability.4ii
Ecological - the ability of the catchment or land system to maintain the services that ecosystems provide (e.g. clean air and water).4i
Macroeconomic - the ability of regional or national economies and institutional frameworks to continue to meet regional and national goals.4i
SUSTAINABLE AGRICULTURE: An agriculture that is, and will continue to be, profitable for farmers, that will conserve soil and water resources and protect the environment, and that will assure adequate and safe food supplies.4ii
SUSTAINABLE DEVELOPMENT: Development that meets the needs of the present (generation) without compromising the ability of future generations to meet their own needs.4iii
THE ‘40-DAY WAVE’: At irregular intervals of between 30 and 60 days, a disturbance of atmospheric pressure may start over the tropical Indian Ocean and move eastward, like a wave,between latitudes, 100S, at 200-300 kilometres a day.
This wave has been popularly called a ‘40-day wave’, but its irregularity makes ’30 to 60-day wave’ a less misleading term. It is also known as a ‘Madden-Julian Oscillation’, after the scientists who first described it, while climatologists prefer ‘intraseasonal oscillation’.
During the northern Australian summer, the passage of the 30- to 60-day wave is marked by a ‘blow up’ in convention, creating widespread cloud and heavy rainfall, although this may range from ‘a few drops to a deluge’ at any particular location.
In mid-latitudes, the 30- to 60-day wave has most infuence in winter when it may strengthen an upper-level trough, possibly leading to the development of northwest or tropical-extratropical cloud bands or to a tropical-extratropical interaction.
The wave is too unreliable to be used for routine rainfall forecasts at this stage.
TOTAL CATCHMENT MANAGEMENT (TCM):
Government initiative with the principles of balancing the development and
conservation of land, water, vegetation and other natural resources while minimising
land degradation and maintaining high water quality.
TROUGHS IN THE UPPER ATMSOPHERE: Troughs, associated with pools of cold air in the upper atmosphere, will destabilise the underlying airmass, and hence may cause rain. These upper level systems, which may not show on surface pressure charts, are most common in the cooler months. If the low-level airmass is moist and the upper-level trough is slow-moving, widespread heavy rainfall can cause flooding, as in the Charleville floods in Queensland in April 1990.
VARIABLE COSTS: Costs which change according to the size or intensity of the activity, e.g. fuel, seed, drench.
WHOLE FARM BUDGET: A budget showing the expected outcomes of a farm plan, as it effects the entire farm's profitability.
WHOLE FARM PLANNING: A process that assists landholders to analyse the farm operation from the ecological, economic and social perspectives and integrates these perspectives in redesigning farm layout and management in order to ensure more sustainable production.5
WORKING CAPITAL: Capital needed for the day to day operation of a farm.
REFERENCES FOR VOCABULARY / GLOSSARY
1. Drought Policy Review Task Force 1990, Managing for Drought, Final Report, Volume 2, Australian Government Publishing Service, Canberra.
2. Bureau of Meteorology (undated), Seasonal Climate Outlook Service, National Climate Centre, Melbourne.
3. Charman, P.E.V. & Murphy, B.W. 1991, Soils - Their Properties and Management, Sydney University Press.
4.i Lowrance, R., Hendrix, P. & Odum, E. 1986, An Hierarchical Approach to Sustainable Agriculture, Am, J. Alt Agric 1 (4):169-173. Quoted in Reeve, I.J. 1990, Sustainable Agriculture: Ecological Imperative or Economic Impossibility, Rural Development Centre, UNE, Armidale.
4.ii Schaller, N., 1989, A Look at low input sustainable agriculture, paper presented at the Oklahoma Agricultural Policy 1989 Conference, Oklahoma City, 28 March. Quoted in Reeve, I.J. 1990, Sustainable Agriculture: Ecological Imperative or Economic Impossibility, Rural Development Centre, UNE, Armidale.
4.iii World Commission on Environment & Development 1987, Our Common Future, Oxford University Press, London. Quoted in Reeve, I.J. 1990, Sustainable Agriculture: Ecological Imperative or Economic Impossibility, Rural Development Centre, UNE, Armidale.
5. Sandilands, J. (compiler), 1990, On Borrowed Time - a Guide to the Potter Farm Plan, The Ian Potter Foundation, Melbourne.