Soil types of the Burnett River Catchment Considerations for irrigating with saline water

Transcription

1 Soil types of the Burnett River Catchment Considerations for irrigating with saline water Purpose: This fact sheet forms part of a series addressing saline irrigation water in the Burnett River catchment, aimed at providing information and guidance to local irrigators about how to ascertain and manage their salinity issue/s. The purpose of this fact sheet is to provide information about the 13 broad soil groups within the Burnett Catchment; their common characteristics and the implication of these with regard to irrigating with saline water. Determining what your soil type is and how it is likely to behave under such conditions will assist with management decision making. Refer also to the Irrigation water quality factsheet. How to use the factsheet: This factsheet should be used in conjunction with the Wide Bay Burnett Soil Grouping spatial file (.kml). To identify which of the 13 broad soil types are located on your property, load the.kml file into Google Earth and zoom to your property. For information relating to the soil types present, refer to the relevant Soil Group section below. It is also recommended that you download the applicable Land Resource Assessment Report and Map from the website listed below (see item 2) for more detailed information. Where to find more detailed information about soils on your property: 1. General soils information & factsheets: Website 2. Land Resource Assessment Reports & Maps: n=derm&url=%2fliberty%2flibraryhome.do 3. Property soil maps (i.e. select map type e.g. land suitability): property/vegetation map request Qld Globe Queensland Globe is a free mapping and data online interactive tool, which displays Queensland Government spatial datasets using the Google Earth platform. (Soil data to be available shortly): data/queensland globe/about Department of Natural Resources & Mines (DNRM) Soils Unit in Bundaberg: Contact Phone: (07) soil.enquiry@dnrm.qld.gov.au Address: Enterprise St, Bundaberg Cautionary Note: Information provided in this factsheet is meant as a guide only. All soil mapping/grouping information is subject to the scale at which it was captured and will therefore require ground truthing at the property level. Similarly, it is important to undertake EC (i.e. salinity level) sampling of local soil and water regularly, in order to adjust management accordingly. It is strongly recommended that you seek professional agronomic advice. 1 25

2 Definitions & Terminology: Soil Groups Soils within the Wide Bay Burnett have been lumped up into 13 broad soil groups, based on similar permeability and drainage attributes (primarily derived from soil profile clay content and sodicity). Soil Texture Soil texture refers to the amount of sand, loam and clay present within a soil and is expressed in terms of clay content (% clay). For simplicity, four main texture categories are shown below, ranging from lighter textured sand to heavier textured clay. Soil texture influences others soil properties, including permeability. Approximate clay content (%) of broad soil textures Sand Loam Clay Loam Clay < 10 % % % > 35 % Source: Adapted from Australian Soil & Land Survey Field Handbook 3 rd Edition (2009, p ) Texture Contrast Soils / Duplex Soils A texture contrast soil (also called a duplex soil) refers to a soil with a lighter textured surface soil over a heavier textured subsoil. The change between the two must be abrupt and constitute a difference in clay content of at least 20%. Sodicity Sodicity refers to the presence of a high proportion of sodium (Na+) ions relative to other cations within a soil sample (in either exchangeable and/or soluble form) (DNR, 1997, p. 203). High levels of sodicity will affect how a soil behaves after medium to long term exposure to saline water. Sodicity levels are categorised below. Soil Sodicity levels Low Medium High Sodicity Level: (Non sodic) (Sodic) (Strongly sodic) ESP: <6 % 6 15 % > 15% Source: Baker & Eldershaw (1993, p.39) NOTE: Saline water counteracts the effects of soil dispersion. Once water salinity returns to low levels soil dispersion may result in sodic soils. Dispersion: Dispersion refers to the complete breakdown of soil aggregates into primary particles of sand, silt and clay in saturated soils, when the attractive forces between the soil particles are not strong enough to hold them together. Dispersion may be quick (minutes) or slow (hours). Sodic soils are generally dispersive soils have exchangeable sodium percentages of greater than six percent. Note: Not all sodic soils are susceptible to dispersion. A sodic soil s tendency to disperse is affected by soil ph and clay mineralogy. Exchangeable Sodium Percentage (ESP): 2 25

3 Exchangeable Sodium Percentage (ESP) is the proportion of sodium adsorbed to the surface of clay particles (as a proportion of total cation exchange capacity), expressed as a percentage. ESP is commonly used as measure of soil sodicity (DNR, 1997, p. 200). Permissible Sodium Adsorption Ration (SAR) Sodium Adsorption Ratio (SAR) refers to the relative content of sodium, compared to calcium and magnesium, in a soil solution or water that approximates the ESP of the soil. The relationship between SAR and ESP is based on the Gapon ion exchange relationship (DNR, 1997, p. 203). Salinity The level of salt within a soil or water sample, commonly referred to as salinity, is measured in terms of electrical conductivity (EC) and is expressed in units of deci seimens per metre (ds/m). For ease of comparison, salinity levels have been categorised as follows: Plant salt tolerance grouping 1 Equivalent EC 1:5 reading, based on clay content of soil Soil salinity (ds/m) rating 10 20% clay 20 40% clay 40 60% clay 60 80% clay Sensitive crops < 0.07 < 0.09 < 0.12 < 0.15 very low Moderately sensitive crops low Moderately tolerant crops medium Tolerant crops high Very tolerant crops very high Generally too saline for crops > 0.93 > 1.21 > 1.53 > 1.87 extreme Source: Adapted from Salinity Management Handbook DNRQ Pg 77 Drainage & Permeability Drainage refers to local soil wetness conditions likely to occur in most years. It is determined based on both internal and external attributes (e.g. soil texture and slope). Permeability is independent of climate and drainage and is controlled by the least permeable layer in the soil. Permeability is inferred from internal soil attributes only (e.g. texture, structure and porosity). Risk to declining structure ratings The overall risk of soils to structural decline as a result of increased exposure to salinised and sodic water) has been categorised into low, medium and high and descriptions are provided below: Risk Low Moderate High Description of risk to declining soil structure Minor impact on soil physical and chemical properties. Permeability of soil will remain unchanged. Soil will require only minor or no intervention to remain healthy. Infrequent monitoring of the soil resource is recommended. Salt accumulation is likely to be leached out of the soil profile with seasonal rainfall and standard irrigation/agronomic practices. Moderate impact on soil physical and chemical properties. Permeability of soil likely to be reduced. Increased sodicity in the soil may require the application of soil conditioners (e.g. gypsum/organic matter). Regular monitoring of the soil and water resource is recommended for the identification of suitable management strategy. Significant impact on soil physical and chemical properties in the medium to longer term. Permeability of soil will be reduced resulting in increased surface runoff and potentially erosion. Increased sodicity in the soil will require the application of soil conditioners (e.g. gypsum/organic matter). Regular monitoring of the soil and water resource is recommended for the identification of suitable management strategies. Improved irrigation management practices are recommended to manage soil chemical / physical properties to avoid long term impacts. 3 25

4 Soil Group 1 Soil Description: Landform: Common Soil Type Names: Soil Grouping Name: Massive sandy surface over a structured clay subsoil Plains or hillslopes Gooburrum, Meadowvale, Farnsfield, Quart SR1 Dermosols (sandy surface); includes non sodic Chromosols/Kurosols/Kandosols/Calcarosols 4 25

5 Texture Group Permeability Drainage Sodicity* Soil Salinity Surface Sand to loam High Rapid Low Low Subsoil Clay loam to clay High Well drained Low Low Risk to declining structure & permeability as a result irrigating with water high in sodium salts Permissible SAR Low <8 13 Key Considerations: Confirm that the soil mapping accurately reflects what is seen on the ground. Monitoring soil salt levels in the root zone and below is recommended to ensure salts are not concentrating. Maintain soil moisture between irrigation events to reduce the salinity levels concentrating in the soil. Growing crops sensitive to specific ions may require leaching to ensure plant toxicities do not occur (e.g. avocado sensitivity to chloride ions). Monitor soil surface for soil structure decline and reduced permeability manage as situation allows (e.g. apply gypsum or organic matter etc.) Apply soil ameliorants/conditioners (e.g. gypsum) to assist with the removal of sodium from the soil profile. Note: quantity and timing is critical. Minimise the area where saline water is applied, to reduce the salt stored in the soil. Application of gypsum prior to rainfall events may assist with flushing of salts from the soil profile. Maintain surface mulch to reduce salting of the soil surface as a result of evaporation. Maintaining soil health through organic matter retention, good nutrient management, and minimal traffic will increase soil resilience to the effects of irrigation induced soil salinity. Maintain surface mulch to reduce erosion of the soil surface as a result of rainfall and irrigation. Add organic matter/mulch to improve soil structure and surface permeability and to protect form rain drop impact (and consequent erosion). Consider planned leaching events at key salinity stress periods (e.g. for young or flowering crop) to manage soil salinity. Choose the best irrigation method that provides best water efficiency whilst conserving potential salt accumulation in the soil profile. Over irrigating will reduce irrigation efficiency and may result in the loss of nutrients or pesticides and further dissolution of salts from the soil profile. Excessive leaching may result in seepage or the contribution of a shallow groundwater table lower in the landscape. 5 25

6 Soil Group 2 & 3 Soil Description: Landform: Common Soil Type Names: Soil Grouping Loamy to clay loamy surface over structured clay subsoil. Plains, hillslopes or alluvial plains Kepnock, Oakwood, Isis, Flagstone, Gahan, Otoo, Mary, Watalgan, Mondure SR2 Dermosols (sealing loamy surface); includes non sodic Chromosols/Kurosols/Kandosols SR3 Dermosols (structured clay, clay loam surface) 6 25

7 Texture Group Permeability Drainage Sodicity* Soil Salinity Surface Loam to clay loam Moderate Well Low Low Subsoil Clay Moderate Moderately Low to Low to well moderate moderate Risk to declining structure & permeability as a result irrigating with water high in sodium salts Permissible SAR Low <5 13 Key Considerations: Confirm that the soil mapping accurately reflects what is seen on the ground. Monitoring soil salt levels in the root zone and below is recommended to ensure salts are not concentrating. Maintain soil moisture between irrigation events to reduce the salinity levels concentrating in the soil. Growing crops sensitive to specific ions may require leaching to ensure plant toxicities do not occur (e.g. avocado sensitivity to chloride ions). Monitor soil surface for soil structure decline and reduced permeability manage as situation allows (e.g. apply gypsum or organic matter etc.) Apply soil ameliorants/conditioners (e.g. gypsum) to assist with the removal of sodium from the soil profile. Note: quantity and timing is critical. Minimise the area where saline water is applied, to reduce the salt stored in the soil. Application of gypsum prior to rainfall events may assist with flushing of salts from the soil profile. Maintain surface mulch to reduce salting of the soil surface as a result of evaporation. Maintaining soil health through organic matter retention, good nutrient management, and minimal traffic will increase soil resilience to the effects of irrigation induced soil salinity. Maintain surface mulch to reduce erosion of the soil surface as a result of rainfall and irrigation. Add organic matter/mulch to improve soil structure and surface permeability and to protect form rain drop impact (and consequent erosion). Consider planned leaching events at key salinity stress periods (e.g. for young or flowering crop) to manage soil salinity. Choose the best irrigation method that provides best water efficiency whilst conserving potential salt accumulation in the soil profile. High clay content, compaction or soil sodicity can limit the leaching of salts in this soil type Excessive leaching may result in seepage or the contribution of a shallow groundwater table lower in the landscape. 7 25

8 Soil Group 4 Soil Description: Landform: Common Soil Type Names: Soil Grouping Structured clay soil (often red). Plains, hillcrests or hillslopes Childers, Wongarra, Telegraph SR4 Ferrosols 8 25

9 Texture Group Permeability Drainage Sodicity* Soil Salinity Surface Clay loam to clay High Well drained Low Low Subsoil Clay High Well drained Low Low Risk to declining structure & permeability as a result irrigating with water high in sodium salts Permissible SAR Low <5 10 Key Considerations: Confirm that the soil mapping accurately reflects what is seen on the ground. Monitoring soil salt levels in the root zone and below is recommended to ensure salts are not concentrating. Maintain soil moisture between irrigation events to reduce the salinity levels concentrating in the soil. Growing crops sensitive to specific ions may require leaching to ensure plant toxicities do not occur (e.g. avocado sensitivity to chloride ions). Monitor soil surface for soil structure decline and reduced permeability manage as situation allows (e.g. apply gypsum or organic matter etc.) Minimise the area where saline water is applied, to reduce the salt stored in the soil. Application of gypsum prior to rainfall events may assist with flushing of salts from the soil profile. Maintain surface mulch to reduce salting of the soil surface as a result of evaporation. Maintaining soil health through organic matter retention, good nutrient management, and minimal traffic will increase soil resilience to the effects of irrigation induced soil salinity. Maintain surface mulch to reduce erosion of the soil surface as a result of rainfall and irrigation. Add organic matter/mulch to improve soil structure and surface permeability and to protect form rain drop impact (and consequent erosion). Consider planned leaching events at key salinity stress periods (e.g. for young or flowering crop) to manage soil salinity. Choose the best irrigation method that provides best water efficiency whilst conserving potential salt accumulation in the soil profile. Over irrigating will reduce irrigation efficiency and may result in the loss of nutrients or pesticides and further dissolution of salts from the soil profile. High clay content, compaction or soil sodicity can limit the leaching of salts in this soil type Excessive leaching may result in seepage or the contribution of a shallow groundwater table lower in the landscape. 9 25

10 Soil Group 5 Soil Description: Landform: Common Soil Type Names: Soil Grouping Seasonally wet. Sandy surface of varying thicknesses over a nonsodic to sodic subsoils (often texture contrast soils) Plains, hillslopes or drainage lines Alloway, Mahogany, Robur, Kinkuna, Wallum SR5 Hydrosols (sandy surfaced) 10 25

11 Texture Group Permeability Drainage Sodicity* Soil Salinity Surface Sand to loam High Poorly Low Low to high Subsoil Sand to clay Slow to high Poorly Low to moderate Low to high NOTE: Surface depth can be variable. These soils are prone to surface salting as a result of a shallow groundwater table. Risk to declining structure & permeability as a result irrigating with water high in sodium salts Permissible SAR Low <5 Key Considerations: Confirm that the soil mapping accurately reflects what is seen on the ground. Monitoring soil salt levels in the root zone and below is recommended to ensure salts are not concentrating. Knowledge of sodium levels (or SAR) in irrigation water is critical for managing soil health following irrigation applications. Maintain soil moisture between irrigation events to reduce the salinity levels concentrating in the soil. Growing crops sensitive to specific ions may require leaching to ensure plant toxicities do not occur (e.g. avocado sensitivity to chloride ions). Monitor soil surface for soil structure decline and reduced permeability manage as situation allows (e.g. apply gypsum or organic matter etc.) Apply soil ameliorants/conditioners (e.g. gypsum) to assist with the removal of sodium from the soil profile. Note: quantity and timing is critical. Minimise the area where saline water is applied, to reduce the salt stored in the soil. Application of gypsum prior to rainfall events may assist with flushing of salts from the soil profile. Maintain surface mulch to reduce salting of the soil surface as a result of evaporation. Maintaining soil health through organic matter retention, good nutrient management, and minimal traffic will increase soil resilience to the effects of irrigation induced soil salinity. Maintain surface mulch to reduce erosion of the soil surface as a result of rainfall and irrigation. Add organic matter/mulch to improve soil structure and surface permeability and to protect form rain drop impact (and consequent erosion). Consider planned leaching events at key salinity stress periods (e.g. for young or flowering crop) to manage soil salinity. Choose the best irrigation method that provides best water efficiency whilst conserving potential salt accumulation in the soil profile. Where irrigating a salt sensitive crop, improve drainage to assist the leaching of salts from the root zone (e.g. mounding). Manage erosion risk. High clay content, compaction, soil sodicity, or a high water table can limit the leaching of salts in this soil. Over irrigation can cause waterlogging

12 Soil Group 6 Soil Description: Landform: Common Soil Type Names: Soil Grouping Seasonally wet. Loamy surface over a clay sodic subsoils (often texture contrast soils). Plains, hillslopes or drainage lines Clayton, Alloway, Kalah (Tirroan, Kolbore, Robur, Winfield) SR6 Hydrosols (sealing loamy surfaced) 12 25

13 Texture Group Permeability Drainage Sodicity* Soil Salinity Surface Loam to clay loam Moderate Poor Low Low to high Subsoil Clay Slow Poor Moderate to high Low to high NOTE: These soils are prone to surface salting as a result of a shallow groundwater table. Risk to declining structure & permeability as a result irrigating with water high in sodium salts Permissible SAR Moderate to high <5 Key Considerations: Confirm that the soil mapping accurately reflects what is seen on the ground. Monitoring soil salt levels in the root zone and below is recommended to ensure salts are not concentrating. Knowledge of sodium levels (or SAR) in irrigation water is critical for managing soil health following irrigation applications. Maintain soil moisture between irrigation events to reduce the salinity levels concentrating in the soil. Growing crops sensitive to specific ions may require leaching to ensure plant toxicities do not occur (e.g. avocado sensitivity to chloride ions). Monitor soil surface for soil structure decline and reduced permeability manage as situation allows (e.g. apply gypsum or organic matter etc.) Apply soil ameliorants/conditioners (e.g. gypsum) to assist with the removal of sodium from the soil profile. Note: quantity and timing is critical. Minimise the area where saline water is applied, to reduce the salt stored in the soil. Application of gypsum prior to rainfall events may assist with flushing of salts from the soil profile. Maintain surface mulch to reduce salting of the soil surface as a result of evaporation. Maintaining soil health through organic matter retention, good nutrient management, and minimal traffic will increase soil resilience to the effects of irrigation induced soil salinity. Maintain surface mulch to reduce erosion of the soil surface as a result of rainfall and irrigation. Add organic matter/mulch to improve soil structure and surface permeability and to protect form rain drop impact (and consequent erosion). Consider planned leaching events at key salinity stress periods (e.g. for young or flowering crop) to manage soil salinity. Choose the best irrigation method that provides best water efficiency whilst conserving potential salt accumulation in the soil profile. Where irrigating a salt sensitive crop, improve drainage to assist the leaching of salts from the root zone (e.g. mounding). Manage erosion risk. High clay content, compaction, soil sodicity, or a high water table can limit the leaching of salts in this soil. Over irrigation can cause waterlogging

14 Soil Group 7 Soil Description: Landform: Common Soil Type Names: Soil Grouping Seasonally wet. Clay loam or clay surface over structured sodic subsoils (sometimes texture contrast soils). Plains, hillslopes or drainage lines Fairydale, Fairymead, Ashgrove, Bingera, Tandora SR7 Hydrosols (structured clay/clay loam surface) including Organosols 14 25

15 Texture Group Permeability Drainage Sodicity* Soil Salinity Surface Clay loam to clay Moderate Poor Low to moderate Low to high Subsoil Clay Slow Poor Moderate to high Low to high Risk to declining structure & permeability as a result irrigating with water high in sodium salts Permissible SAR High <5 Key Considerations: Confirm that the soil mapping accurately reflects what is seen on the ground. Monitoring soil salt levels in the root zone and below is recommended to ensure salts are not concentrating. Knowledge of sodium levels (or SAR) in irrigation water is critical for managing soil health following irrigation applications. Maintain soil moisture between irrigation events to reduce the salinity levels concentrating in the soil. Growing crops sensitive to specific ions may require leaching to ensure plant toxicities do not occur (e.g. avocado sensitivity to chloride ions). Monitor soil surface for soil structure decline and reduced permeability manage as situation allows (e.g. apply gypsum or organic matter etc.) Apply soil ameliorants/conditioners (e.g. gypsum) to assist with the removal of sodium from the soil profile. Note: quantity and timing is critical. Minimise the area where saline water is applied, to reduce the salt stored in the soil. Application of gypsum prior to rainfall events may assist with flushing of salts from the soil profile. Maintain surface mulch to reduce salting of the soil surface as a result of evaporation. Maintaining soil health through organic matter retention, good nutrient management, and minimal traffic will increase soil resilience to the effects of irrigation induced soil salinity. Maintain surface mulch to reduce erosion of the soil surface as a result of rainfall and irrigation. Add organic matter/mulch to improve soil structure and surface permeability and to protect form rain drop impact (and consequent erosion). Consider planned leaching events at key salinity stress periods (e.g. for young or flowering crop) to manage soil salinity. Choose the best irrigation method that provides best water efficiency whilst conserving potential salt accumulation in the soil profile. Where irrigating a salt sensitive crop, improve drainage to assist the leaching of salts from the root zone (e.g. mounding). Manage erosion risk. High clay content, compaction, soil sodicity, or a high water table can limit the leaching of salts in this soil. Over irrigation can cause waterlogging

16 Soil Group 8 Soil Description: Landform: Common Soil Type Names: Soil Grouping: Shallow soils over rock. NB: Soil grouping is complex and may include other soils. Hillslopes or hillcrests Eerwah, Riverleigh, Cd.3 SR8 Rudosols/Tenosols (loamy) 16 25

17 Texture Group Permeability Drainage Sodicity* Soil Salinity Moderate to Imperfect to Surface Sand to clay Low Low high rapid Subsoil Rock NA NA NA NA Risk to declining structure & permeability as a result irrigating with water high in sodium salts Permissible SAR Low to Moderate < 5 20 Key Considerations: Confirm that the soil mapping accurately reflects what is seen on the ground. Monitoring soil salt levels in the root zone and below is recommended to ensure salts are not concentrating. Knowledge of sodium levels (or SAR) in irrigation water is critical for managing soil health following irrigation applications. Maintain soil moisture between irrigation events to reduce the salinity levels concentrating in the soil. Growing crops sensitive to specific ions may require leaching to ensure plant toxicities do not occur (e.g. avocado sensitivity to chloride ions). Monitor soil surface for soil structure decline and reduced permeability manage as situation allows (e.g. apply gypsum or organic matter etc.) Apply soil ameliorants/conditioners (e.g. gypsum) to assist with the removal of sodium from the soil profile. Note: quantity and timing is critical. Minimise the area where saline water is applied, to reduce the salt stored in the soil. Application of gypsum prior to rainfall events may assist with flushing of salts from the soil profile. Maintain surface mulch to reduce salting of the soil surface as a result of evaporation. Maintaining soil health through organic matter retention, good nutrient management, and minimal traffic will increase soil resilience to the effects of irrigation induced soil salinity. Maintain surface mulch to reduce erosion of the soil surface as a result of rainfall and irrigation. Add organic matter/mulch to improve soil structure and surface permeability and to protect form rain drop impact (and consequent erosion). Consider planned leaching events at key salinity stress periods (e.g. for young or flowering crop) to manage soil salinity. Choose the best irrigation method that provides best water efficiency whilst conserving potential salt accumulation in the soil profile. Over irrigating will reduce irrigation efficiency and may result in the loss of nutrients or pesticides and further dissolution of salts from the soil profile. High clay content, compaction or soil sodicity can limit the leaching of salts in this soil type Excessive leaching may result in seepage or the contribution of a shallow groundwater table lower in the landscape

18 Soil Group 9 Soil Description: Landform: Common Soil Type Names: Soil Grouping: Loamy to clay loamy surface, sodic texture contrast soil Plains, hillslopes or old alluvial plains Tirroan, Avondale, Auburn, Kolan, Peep, Marshlands, Booloongie, Givleda, Butcher, Turpin, Moorland, Washpool SR9 Sodosols (loamy surface) including sodic Chromosols/Kurosols/ Kandosols/Calcarosols 18 25

19 Texture Group Permeability Drainage Sodicity* Soil Salinity Loam to clay Moderate to Low to Surface Moderate Low loam Imperfect moderate Moderate to Moderate to Subsoil Clay Slow High Imperfect high Risk to declining structure & permeability as a result irrigating with water high in sodium salts Permissible SAR High < 5 Key Considerations: Confirm that the soil mapping accurately reflects what is seen on the ground. Monitoring soil salt levels in the root zone and below is recommended to ensure salts are not concentrating. Knowledge of sodium levels (or SAR) in irrigation water is critical for managing soil health following irrigation applications. Maintain soil moisture between irrigation events to reduce the salinity levels concentrating in the soil. Growing crops sensitive to specific ions may require leaching to ensure plant toxicities do not occur (e.g. avocado sensitivity to chloride ions). Monitor soil surface for soil structure decline and reduced permeability manage as situation allows (e.g. apply gypsum or organic matter etc.) Apply soil ameliorants/conditioners (e.g. gypsum) to assist with the removal of sodium from the soil profile. Note: quantity and timing is critical. Minimise the area where saline water is applied, to reduce the salt stored in the soil. Application of gypsum prior to rainfall events may assist with flushing of salts from the soil profile. Maintain surface mulch to reduce salting of the soil surface as a result of evaporation. Maintaining soil health through organic matter retention, good nutrient management, and minimal traffic will increase soil resilience to the effects of irrigation induced soil salinity. Maintain surface mulch to reduce erosion of the soil surface as a result of rainfall and irrigation. Add organic matter/mulch to improve soil structure and surface permeability and to protect form rain drop impact (and consequent erosion). Consider planned leaching events at key salinity stress periods (e.g. for young or flowering crop) to manage soil salinity. Choose the best irrigation method that provides best water efficiency whilst conserving potential salt accumulation in the soil profile. Where irrigating a salt sensitive crop, improve drainage to assist the leaching of salts from the root zone (e.g. mounding). Manage erosion risk. High clay content, compaction, soil sodicity, or a high water table can limit the leaching of salts in this soil. Over irrigation can cause waterlogging

20 Soil Group 10/11 Soil Description: Landform: Common Soil Type Names: Soil Grouping: Sandy surface, sodic texture contrast soil. Plains, hillslopes or old alluvial plains Summerville, Turpin, Gall, Tirroan, Crossing, Gigoon SR10 Sodosols (moderately deep (>0.5m) sandy surface); including sodic Chromosols/Kurosols/ Kandosols 20 25

21 Texture Group Permeability Drainage Sodicity* Soil salinity Surface Sand High Moderately well to imperfect Low Low Subsoil Clay Slow Moderately Moderate to well to High high imperfect NOTE: Depth of sandy surface can vary between soils Risk to declining structure & permeability as a result irrigating with water high in sodium salts Permissible SAR Moderate < 5 Key Considerations: Confirm that the soil mapping accurately reflects what is seen on the ground. Monitoring soil salt levels in the root zone and below is recommended to ensure salts are not concentrating. Knowledge of sodium levels (or SAR) in irrigation water is critical for managing soil health following irrigation applications. Maintain soil moisture between irrigation events to reduce the salinity levels concentrating in the soil. Growing crops sensitive to specific ions may require leaching to ensure plant toxicities do not occur (e.g. avocado sensitivity to chloride ions). Monitor soil surface for soil structure decline and reduced permeability manage as situation allows (e.g. apply gypsum or organic matter etc.) Apply soil ameliorants/conditioners (e.g. gypsum) to assist with the removal of sodium from the soil profile. Note: quantity and timing is critical. Minimise the area where saline water is applied, to reduce the salt stored in the soil. Application of gypsum prior to rainfall events may assist with flushing of salts from the soil profile. Maintain surface mulch to reduce salting of the soil surface as a result of evaporation. Maintaining soil health through organic matter retention, good nutrient management, and minimal traffic will increase soil resilience to the effects of irrigation induced soil salinity. Maintain surface mulch to reduce erosion of the soil surface as a result of rainfall and irrigation. Add organic matter/mulch to improve soil structure and surface permeability and to protect form rain drop impact (and consequent erosion). Consider planned leaching events at key salinity stress periods (e.g. for young or flowering crop) to manage soil salinity. Choose the best irrigation method that provides best water efficiency whilst conserving potential salt accumulation in the soil profile. Where irrigating a salt sensitive crop, improve drainage to assist the leaching of salts from the root zone (e.g. mounding). Manage erosion risk. High clay content, compaction, soil sodicity, or a high water table can limit the leaching of salts in this soil. Over irrigation can cause waterlogging

22 Soil Group 12 Soil Description: Landform: Common Soil Type Names: Soil Grouping: Deep sandy and loamy soils. Plains and alluvial plans Burnett, Moore Park, Dillan, Burrum, Tantitha, Toogum, Fison, Wallum, Colvin SR12 Tenosols/Rudosols/Podosols (sandy) 22 25

23 Texture Group Permeability Drainage Sodicity* Soil salinity Surface Sand to loam High Rapid Low Low Subsoil Sand to loam High Rapid Low Low Risk to declining structure and permeability as a result irrigating with water high in sodium salts Permissible SAR Low <13 to 20 Key Considerations: Confirm that the soil mapping accurately reflects what is seen on the ground. Monitoring soil salt levels in the root zone and below is recommended to ensure salts are not concentrating. Maintain soil moisture between irrigation events to reduce the salinity levels concentrating in the soil. Growing crops sensitive to specific ions may require leaching to ensure plant toxicities do not occur (e.g. avocado sensitivity to chloride ions). Monitor soil surface for soil structure decline and reduced permeability manage as situation allows (e.g. apply gypsum or organic matter etc.) Minimise the area where saline water is applied, to reduce the salt stored in the soil. Application of gypsum prior to rainfall events may assist with flushing of salts from the soil profile. Maintain surface mulch to reduce salting of the soil surface as a result of evaporation. Maintaining soil health through organic matter retention, good nutrient management, and minimal traffic will increase soil resilience to the effects of irrigation induced soil salinity. Maintain surface mulch to reduce erosion of the soil surface as a result of rainfall and irrigation. Add organic matter/mulch to improve soil structure and surface permeability and to protect form rain drop impact (and consequent erosion). Consider planned leaching events at key salinity stress periods (e.g. for young or flowering crop) to manage soil salinity. Choose the best irrigation method that provides best water efficiency whilst conserving potential salt accumulation in the soil profile. Over irrigating will reduce irrigation efficiency and may result in the loss of nutrients or pesticides and further dissolution of salts from the soil profile. Excessive leaching may result in seepage or the contribution of a shallow groundwater table lower in the landscape

24 Soil Group 13 Soil Description: Landform: Common Soil Type Names: Soil Grouping: Cracking clays. Plains and alluvial plans Walla, Rubyanna SR13 Vertosols 24 25

25 Texture Group Permeability Drainage Sodicity* Soil salinity Imperfect to Low to Surface Clay Moderate moderately Low to high moderate well Subsoil Clay Slow to moderate Imperfect to moderately well Moderate to high Moderate to high Risk to declining structure & permeability as a result irrigating with water high in sodium salts Permissible SAR Moderate <5 Key Considerations: Confirm that the soil mapping accurately reflects what is seen on the ground. Monitoring soil salt levels in the root zone and below is recommended to ensure salts are not concentrating. Knowledge of sodium levels (or SAR) in irrigation water is critical for managing soil health following irrigation applications. Maintain soil moisture between irrigation events to reduce the salinity levels concentrating in the soil. Growing crops sensitive to specific ions may require leaching to ensure plant toxicities do not occur (e.g. avocado sensitivity to chloride ions). Monitor soil surface for soil structure decline and reduced permeability manage as situation allows (e.g. apply gypsum or organic matter etc.) Apply soil ameliorants/conditioners (e.g. gypsum) to assist with the removal of sodium from the soil profile. Note: quantity and timing is critical. Minimise the area where saline water is applied, to reduce the salt stored in the soil. Application of gypsum prior to rainfall events may assist with flushing of salts from the soil profile. Maintain surface mulch to reduce salting of the soil surface as a result of evaporation. Maintaining soil health through organic matter retention, good nutrient management, and minimal traffic will increase soil resilience to the effects of irrigation induced soil salinity. Maintain surface mulch to reduce erosion of the soil surface as a result of rainfall and irrigation. Add organic matter/mulch to improve soil structure and surface permeability and to protect form rain drop impact (and consequent erosion). Consider planned leaching events at key salinity stress periods (e.g. for young or flowering crop) to manage soil salinity. Choose the best irrigation method that provides best water efficiency whilst conserving potential salt accumulation in the soil profile. Where irrigating a salt sensitive crop, improve drainage to assist the leaching of salts from the root zone (e.g. mounding). Manage erosion risk. High clay content, compaction, soil sodicity, or a high water table can limit the leaching of salts in this soil. Over irrigation can cause waterlogging