Tailoring the workshop to the needs of the specific group (making it relevant) Local information (background information on the participants, age range, gender, agricultural area, farms and previous seasons, etc.) can be important. Slides should include the workshop objectives, learning outcomes for participants, and a timeline for the day.
How much has leakage changed from pre-clearing native vegetation to post- clearing annual cereal crops in the WA wheatbelt?
Most of the salt in the soil profiles in our landscapes has been deposited by rainfall. Changes in hydrological balances due to clearance have led to rising groundwater levels and the development of secondary salinization.
What is the average % of cleared land in the wheatbelt of WA affected by salinity?
Quiz questions and answers with additional background information 1) What is the main cause of new salinity in the wheat belt of WA?. Farmers' estimates will probably be on the low side and the experts' figures on the high side.
Land Monitor estimates are around ha and the omission of barley grass land on this figure is a huge mistake. The reality is probably somewhere in between these numbers, and it depends on what you're going to report as salty earth.
What is the major origin of the salt causing secondary salinity?
Experts' estimates are probably based on interpretation of medium-scale aerial and satellite images and probably a generous estimate. Farmers' estimates are probably too low, as they do not take into account the salinized land that is not scorched or the flat area of barley grass, i.e.
What are the respective amounts of salt deposited annually WA?
What percentage of a catchment needs planting to perennials to make a big difference to salinity in the wheatbelt?
On average, how much salt per hectare is stored in the ground in the wheatbelt?
QUIZ
What is the major cause of new salinity in the wheatbelt of WA?
How much has leakage changed from pre-clearing native vegetation to post-clearing annual cereal crops in the WA wheatbelt?
What is the average percentage of cleared land in the wheatbelt of WA affected by salinity?
In what part of the soil profile is most salt stored?
What percentage of a catchment needs planting to perennials to make a big difference to salinity in the wheatbelt?
On average, how much salt per hectare is stored in the ground in the wheatbelt?
WORKSHOP DETAIL Quiz
AGENDA
Introduction
General
Outcomes for participants
Understanding the cause of salinity
Where does salt come from?
What causes secondary salinity?
Note: Figures for runoff as a percentage of annual rainfall are only an indication based on average seasonal rainfall and standard soil and plant parameters. In low rainfall years, runoff will be reduced and may be low even in pastures; in high rainfall years even perennial plants cannot use all the rainfall at once. The runoff level is indicated as high, medium, or low, based on total runoff mm and soil permeability.
If drainage on a soil is low, a small amount of runoff will eventually fill it, while the same runoff on a more permeable soil will dry out the system. The total mm of runoff coming from different parts of the agricultural system is based on soil types and crop rotations (calculated by AgET). Note: Figures for runoff as a percentage of annual rainfall are only an indication based on average seasonal rainfall and standard soil and plant parameters.
In years with little rainfall, leakage will decrease and may be low even under annuals; in years with a lot of precipitation, even perennial plants cannot use up all the precipitation immediately. Runoff from crops and pastures Runoff from crops and pastures compared to permanent vegetation compared to permanent vegetation. It is important that the length of the production phase after three years of alfalfa is adjusted to suit the course of the seasons and specific soil types, rather than being cultivated for a specific period.
How hydrology interacts with geomorphology to create salinity
What characterises the local landscapes?
Hydrology, hydrogeology, soils and recharge on them What is the magnitude of the
- Recognising salinity
Groundwater flow is limited by aquifer transferability (deep) or aquifer dilution (sit/sandplain) and expresses itself at the surface. Many areas of salinity are caused by surface water problems (eg roads, small culverts, flooding of slopes without earthworks, etc.). Groundwater cannot flow past a geological constriction and builds up until it approaches the surface.
Flow tree for evaluating salinity risk and determining management options available to farmers.
Flow Tree for Evaluating the Risk of Salinity and Determining Management Options Available to Farmers
Salinity risk at local landscape level (What is happening in my area?)
The speed of capillary rise and the height of the capillary fringe depends on the type of soil. Capillary rise may occur in fine-textured (coarse) soils when the water table is within 2 m of the surface (eg clays may have a 2 m capillary fringe). In coarse-textured soils, the capillary bed is much thinner and so evaporation and salt concentration can only occur when the water table is much shallower.
Coarse-textured unconfined aquifers terminate above an impermeable layer (e.g., duplex subsoil) that allows water to seep to the surface and evaporate, leaving salts behind. General information for the south-west of Western Australia shows that shallow piezometers located near discharge zones typically have little variation in water level due to evaporation and use of vegetation (equilibrium). Deep piezometers intercepting semi-confined aquifers at similar locations often show rates of rise on the order of 10 cm/yr, possibly indicating the presence of an upward vertical hydraulic gradient that may ultimately increase the discharge area.
Upper and middle slope catchment areas where recharge dominates usually have groundwater rises of the order of 30 cm/year. With the general exception of shallow piezometers located in discharge areas, seasonal fluctuations of 0.5 to 1 m during an average rainfall season across different landscape positions are common, indicating groundwater response to individual recharge events- ( see Mackie River RCA Report). Comment All pits have upward trends with the greatest rate of increase on the lower slope and mid-slope where salinity has not yet developed.
Model results from Flowtube, AgET and Land Monitor predictions
Do nothing - Recharge under the existing rotation mix is estimated to be 11% of annual rainfall.
What is the risk at the landscape level (Land Monitor)?
For example, in some areas of the catchment, groundwater may be fresh and therefore pose no major threat. Areas mapped as being at risk may also have a deep sandy soil with minimal capillary fringes, thereby preventing capillary rise from causing salinity, even over the longer term. These are not "salinity risk maps"; nor do they identify areas with rising groundwater or water tables.
They indicate "valley floors" where the site is reasonably dissected (so that surface water flow paths can be identified), or where the site is so flat that there is basin drainage. Some of these valley floors/low-lying areas may become saline and/or waterlogged in the future, but this will be determined by a number of other hydrologic factors. Also, areas designated as at risk may have a deep sandy soil with minimal capillary fringe, thus preventing capillary growth to cause salinity, even in the longer term.
Group interpretation (small groups) of local Land Monitor information Divide into groups of three or four farmers. Are there significant threatened areas within the local area and at the farm level. Are there significant threatened areas within the local area and at the farm level.
Identify symptoms of current salinity and signs of potential salinity
Soil types and landscapes with the greatest risk of salinisation?
Overall results show that middle and lower slopes are at risk of salinization within 20 years and that the onset of salinity in middle slopes can be delayed by many years depending on the level of intervention. Examples of such areas include stretches of the Mortlock River East, particularly on the western flank of the catchment around the Dowerin-Meckering Road and south of the Great Eastern Highway between Meckering and Cunderdin. Participants will need to look for landscape features related to expressions of salinity and water logging at the field site.
Landscape map analogy for PURSL
Why does all this matter?
What units are used to measure/describe salinity?
Pre-field activity
Work in groups to plan a salinity management strategy based on information related to the field location. To allow participants to look at the range of resources and information related to a specific site that (time permitting) will be visited in the field. Have the owner of the land present to provide background information on the site.
Divide into groups of three to plan a management strategy for the site based on available information. Have groups present back to all participants before or after the field visit or both. Farmers get to put theory into practice in the field (reinforcement of previous learning).
The time allotted for the field visit should be adapted to the background of the participants. Briefly describe the field activity before you leave, including the tools used in the field. The purpose of this visit is to give the participants on site an overview of the information covered in the workshop.
The effect of salinity on farm production and profitability
Waterlogging and salinity interactions
Waterlogging saturates the pores in the soil that are normally filled with gas, making them oxygen-deficient. If salt accumulates to a significant extent in the shoots, plant growth and survival are affected. The two pots on the left are waterlogged while the two pots on the right are free draining.
Pictures show the effects of waterlogging on wheat grown with (a) no salt, (b) salt equivalent to 4% seawater, and (c) salt equivalent to 20% seawater. The effect of salinity and waterlogging combined has a much more severe effect on plant growth than salinity alone. This indicates the possibility of removing chokes from the surface water drainage system.
Raised beds are an option that can be used to remove the flooding (Barrett-Lennard 2003).
Impact of loss of productivity to profitability of the farm
Assess the salinity risk for your farmland
Farmers put salinity into perspective for their farms and develop a number of long-term and medium-term goals related to salinity management. Have farmers fill out worksheet sections for the estimated areas of both current and potential salinity. Estimate the current value of production on this land (protection value) representing the cost of the "No Change Option".
Complete section at the end of planning worksheets - what are my general medium and long term goals in relation to salinity and recharge management.
Monitoring watertables
Preliminary appraisal of major potential management options for your business
Work in small groups to review the range of salinity management options using planning worksheets. Groups to propose a list of possible options for their business and make a recommendation regarding the best management options for their business. Select one or two PowerPoint slides from the Million Acres Optional Workshops to highlight some of the options you think members of the group might be interested in.
Optional workshops available (on Department of Agriculture website) Simulated Economic Transition Planning (STEP) – is it for me.
Options for managing salinity
Introduction to the STEP Workshops
- Where to next
This may be at the end of this workshop or after participants have had a chance to summarize the information they have received. Lead a session either directly after this workshop or within two to three weeks, while the implications of the workshop are still fresh in the minds of the participants. 4th National Workshop on Productive Use and Rehabilitation of Saline Soils, Albany, March 1996, p. 88-89.
Effect of salt substrate on hourly levels of carbohydrates and inorganic components of barley plants.
