Available in PDF or IBook, these documents include a property overview, detailed production data and management information for each of the Tocal enterprises: beef, dairy, free range eggs and well as horse and sheep breeding. This information can support students using Tocal as a study in a range of NSW syllabuses.
The climate helps determine the type of agriculture that is viable and highlights the risks and uncertainty that are a feature of Australian agriculture. Those working in agriculture are vitally interested in both the weather (day to day experience) and the climate (long term data) that affect their activities.
A large part of reducing risk in agriculture and protecting natural resources comes from being aware of the climate record and seasonal fluctuations. Armed with this knowledge, landholders can set their production at levels that use the land according to its capabilities and generate profit from the land.
The Weather and Climate at Tocal pdf provides more details on the climate records (including graphs) for Tocal and discusses how this information is useful for farm decision making.
Tocal receives more summer rainfall than winter. In January to March there is more than twice the rain of July to September. There are only slightly more rain days in the summer/autumn period, however there are more thunderstorms in summer, bringing heavier falls. Most summer rainfall comes from storms caused by moist air extending southwards from northern Australia and east from the Tasman Sea. Winter rainfall is mainly caused by cold fronts from the mid latitudes. The development of low pressure systems in the Tasman Sea in winter can also bring heavy rain and strong winds.
The lower monthly rainfall figures from July to September are made much worse by the incidence of strong westerly winds causing high evaporation rates. The district rarely receives really good rainfall in spring compared to southern New South Wales. Reliance on the ryegrasses and clovers as the main feed source is therefore difficult and explains the need for summer growing species such as kikuyu.
An understanding of the weather patterns across the Pacific has allowed meteorologists to determine that pressure changes can be used as an indication of changing weather patterns and have developed a system using an indicator known as the Southern Oscillation Index (SOI). Historical data demonstrates that the Southern Oscillation Index (SOI) is often a good predictor of seasonal conditions, but it should not be the sole basis for making decisions about the outlook for agriculture in the Paterson district.
In addition to the SOI, Australia is affected by other variables. The Southern Annular Mode (SAM) affects winds over much of the continent; the Indian Ocean Dipole (IOD) is a measure of sea surface temperatures in the Indian Ocean, and these impact on rainfall patterns.
Other drivers of climate have less effect on Tocal, but a serious influence is the arrival of east coast lows. East coast lows are intense low-pressure systems which occur several times each year off the eastern coast of Australia, in southern Queensland, New South Wales and eastern Victoria. East coast lows will often rapidly intensify overnight, making them one of the more dangerous weather systems to affect the southeast Australian coast. Their effects reach inland as far as Tocal and can cause serious flooding.
Note: the DPI has a series of animations that explain the operation of the climate drivers https://www.dpi.nsw.gov.au/climate-and-emergencies/seasonal-update/climatedogs].
Since European settlement, records suggest that the Paterson River floods on an irregular basis. These floods cause extensive damage to low lying areas. The floods do not follow any particular pattern and have occurred in most months. The most likely time for floods is in the late summer-autumn period.
Flooding mostly effects the rich river flats which may be covered by four metres of water in a big flood. Floods have a huge impact on the operation of the property as they make large areas of the property unusable and hinder stock movement (a problem made worse in 1911 by the establishment of the railway line). While floods cause a lot of inconvenience to farm operations the sediments left behind as the flood recedes are an important factor in the fertility of these flats.
Though the district has a high average annual rainfall by Australian standards, it is still susceptible to droughts.
Droughts cause low levels of paddock stock water and a decline in feed production. Strong westerly winds again cause high evaporation rates. The impacts of drought are felt across the property.
A short but serious dry period occurred in 2017, extending into 2018. Low rainfall during this period led to feed shortages and in particular, the drying of dams and water supplies. Tocal suffered with much of the Lower Hunter, but the effects were much worse in the Upper Hunter. Some relief was felt in the Lower Valley with relieving rains in March 2018.
Paterson's proximity to the coast affects its temperatures by reducing extremes. The area does not receive the intensity of hot days in the summer and cold nights in the winter compared to the Upper Hunter Valley. It is, however, far enough inland to receive some very hot days (>35°C) in most summers and some frosts in most winters.
Severe frosts are uncommon at Tocal. When they occur, they are associated with stationary high pressure systems and still, dry air in mid-winter.
The frost figures show that, as expected, July experiences the most frosts, with August the next most frost-prone month.
Humidity is the actual amount of water vapour in the air and is measured by a wet bulb thermometer.
The humidity data for Tocal shows that humidity, while not fluctuating greatly throughout the year, remains relatively high, which is typical for coastal districts. High humidity is often associated with discomfort in humans and animals when combined with high temperatures. Tocal is far enough from the coastal breezes to experience this discomfort, especially in the summer months.
The Paterson district receives quite a lot of windy days, an important factor to be considered when planning agricultural enterprises. Winds coming from the north-west or west in September and October are beginning to warm up, and can quickly 'burn off' the spring flush of white clover. This important pasture legume is an important feed source in summer, but can almost disappear in the face of these hot north-westerlies.
Thunder occurs about 30 times per year at Tocal and hail occurs on average about once or twice a year; this is less than the number of occurrences on the tablelands and western slopes and usually storms in our region do not cause any damage. Notable severe storms recently occurred on 9 December 1985, 27 November 1988, 20 November 1992 and 4 December 2002.
The Australian bush is susceptible, and adapted, to fire. When high temperatures are combined with low humidity and strong winds, there is always a danger of bushfires if there is sufficient fuel-load to support the spread of fire.
Tocal has been seriously affected by fires on a number of occasions because much of the Tocal property is heavily timbered by dry eucalypt forest that is very exposed to bushfires. Most bushfires burn in the dry season, which at Tocal is in spring or early summer. The chance of a bushfire becoming established depends on the amount of fuel available, the number of days since previous rain, the humidity, the air temperature and the wind speed.
The impacts of fire can be significant on farm operations. Apart from the potential for loss of infrastructure, stock or crops, it can be a costly and time consuming exercise to return the farm to a situation similar to that before the fire. Fences on Tocal have been burnt three times during the first half of the 20th century.
For more detail on the areas addressed here and for information about how we manage the effect of weather and climate download the Weather and Climate at Tocal pdf.