Regional land suitability guidelines for SBC Serial Biological Concentration application

Transcription

1 Regional land suitability guidelines for SBC Serial Biological Concentration application Zahra Paydar, Shahbaz Khan, Mohammad Ali Rahimi Jamnani and John Blackwell CSIRO Land and Water Science Report 46/07 July 2007

2 Copyright and Disclaimer 2007 CSIRO To the extent permitted by law, all rights are reserved and no part of this publication covered by copyright may be reproduced or copied in any form or by any means except with the written permission of CSIRO Land and Water. Important Disclaimer: CSIRO advises that the information contained in this publication comprises general statements based on scientific research. The reader is advised and needs to be aware that such information may be incomplete or unable to be used in any specific situation. No reliance or actions must therefore be made on that information without seeking prior expert professional, scientific and technical advice. To the extent permitted by law, CSIRO (including its employees and consultants) excludes all liability to any person for any consequences, including but not limited to all losses, damages, costs, expenses and any other compensation, arising directly or indirectly from using this publication (in part or in whole) and any information or material contained in it. Cover Photograph: From CSIRO Land and Water Image Gallery: File: PMA07_002_013.jpg Description: Water is remarkably photogenic. This image was created using the amazing ability of water to transmit, disperse and reflect light in ever changing patterns of colour Photographer: Willem van Aken 2006 CSIRO ISSN:

3 Regional land suitability guidelines for SBC application Zahra Paydar a, Shahbaz Khan a,c, Mohammad Ali Rahimi Jamnani b and John Blackwell c a CSIRO Land and Water b Ab_Khak Engineers, Karaj, Iran c Charles Sturt University, Wagga Wagga, NSW Report Title Page i

4 CSIRO Land and Water Science Report 46/07 July 2007 Report Title Page ii

5 Acknowledgements This work has been carried out as part of a suite of activities being undertaken by ACIAR funded project LWR/2000/013: Sustainable agriculture in saline environments through Serial Biological Concentration. The project is a collaborative work with the Department of Primary Industries, Victoria and the Pakistan Agricultural Research Council (PARC). The funding of the ACIAR is gratefully acknowledged. We wish to thank Mr. Mike Morris, Trevor Dowling and Tariq Rana for providing environmental data for the two irrigation areas in this study. Report Title Page iii

6 Executive Summary The disposal of the drainage water from irrigation areas needs careful consideration so that water supplies downstream are not polluted. In the Murray Darling Basin there is an increasing pressure to limit salinity levels in the River Murray by minimising salt load leaving the irrigated catchments of the Basin. Drainage disposal to fresh water bodies is likely to become less acceptable over time hence strategies will have to be considered to manage saline drainage effluent flows from irrigation areas where the salt loads are generated. The ultimate goal of irrigation management should be to minimize the amount of water extracted from a good-quality water supply and to maximize the utilization of the extracted water (achieving high water use efficiency) during irrigation, so that as much of it as possible is consumed in transpiration and as little as possible is wasted and discharged as drainage. On-farm management of drainage effluent has been considered, tested and/or adopted in a number of places around the world. The on-farm practices usually consist of agronomic and engineering techniques applied by the farmers on a field. Many different approaches can be combined for the satisfactory use of drainage water. Drainage water of sufficiently good quality might be used directly for crop production or can be used conjunctively with fresh water. Conjunctive use may involve blending drainage water with better quality water or can be used cyclically with fresh water being applied separately. In cyclic use, the two water sources can be alternated within the cropping season, or the two water sources can be used separately over the season for different crops. The choice of a certain reuse option depends largely on drainage water (quantity, quality and time of availability); crop tolerance to salinity; and availability of fresh water resources. Sequential reuse of drainage water, referred to as SBC (Serial Biological Concentration), involves reuse of drainage water on successively more salt tolerant crops reducing the volume of the effluent while the salinity increases, thus ultimately resulting in a small volume of highly saline effluent for disposal in a small evaporation basin. Not all areas in an irrigation region are suitable for SBC application in terms of effectiveness and the risk of damaging the environment. Identification of the suitable areas requires multi criteria analysis in a spatial platform. The suitability of a site for SBC should be evaluated on the basis of criteria indicative of its potential to create conditions that deteriorate soil, and groundwater conditions. Factors to be considered include the effects of changes in salinity with time, the average salinity distribution in the root zone, interaction with climate variables (ET, rain), and the effects of different soil types. Relevant criteria for considering a site for SBC are primarily: soil salinity and permeability, groundwater depth and groundwater salinity. It should be noted that consideration of the above factors does not take into account the interactive effects of those factors or the dynamics of the processes. Groundwater flow system, for example, is an important factor in delivering the saline water into regional aquifers and its movement should be considered in a more detailed evaluation process. If sufficient suitable areas can not be identified in a region, alternative disposal methods will be required for drainage of irrigated lands. This report describes a methodology to assist in regional planning for the environmentally safe use of SBC technology in the irrigation areas on the Riverine Plain of the Murray-Darling Basin. A GIS-based approach is developed using suitability criteria expected to minimize the risk of off-site effects of this drainage management method. The analysis covers the Murrumbidgee Irrigation Area (MIA) in NSW and the Shepparton Irrigation Region (SIR) in Victoria to identify sites where SBC can be applied with minimum off-site effects and environmental risks. In addition to this regional assessment, a detailed site investigation (to identify site specific characteristics) is required in order to decide whether a particular site is suitable. Report Title Page iv

7 Table of Contents 1. Introduction Management strategies for drainage water reuse Dual rotation cyclic management strategy Sequential reuse of drainage water Regional site suitability criteria Application of the suitability criteria in Irrigation Areas Murrumbidgee Irrigation Area Study area Soils Climate Hydrogeology Groundwater salinity Suitable SBC sites Shepparton Irrigation Region Climate Soils Groundwater and salinity in the Shepparton Irrigation Region Suitable SBC sites Conclusions Appendices Appendix 1. Salt tolerance of crops Appendix 2. Threshold values for reduction in infiltration rate of soils Appendix 3. Spatial data References Report Title Page v

8 1. Introduction Increased intensity of land and water use under large scale irrigation has altered the hydrological regime and resulted in degradation of water quality of the water bodies in irrigated catchments. As much as drainage is needed to eliminate salinity and waterlogging hazards in irrigated lands, the disposal of the drainage water needs careful consideration so that water supplies downstream are not polluted. New strategies are needed to manage saline drainage effluents to diminish such disposals to fresh water bodies over time. The ultimate goal of irrigation management should be to minimize the amount of good quality water extracted for irrigation and to maximize the water use efficiency during irrigation, so that as much of it as possible is consumed in transpiration (hence producing biomass) and as little as possible is wasted. To achieve this goal and due to the high cost of transporting wastewater to a proper disposal site (ocean, salt lakes), the maximum use of any drainage water should be made before ultimate disposal. Reuse of poor quality water (drainage water) requires careful management to prevent the potential problems such as secondary salinisation of the land used. Most of this drainage water, while degraded, is still usable and its reuse through a plant based system will reduce the amount of wastewater requiring further management or disposal. Effective salinity control measures must be implemented to sustain irrigated agriculture and to prevent degradation of existing water resources. Such measures must be considered within the whole irrigation and geohydrologic system. Some practices can be used to control salinity within the crop root zone, while others can control salinity within larger management units (irrigation areas, catchments). The on-farm practices usually consist of agronomic and engineering techniques applied by the farmer at a field scale. The larger scale practices generally consist primarily of engineering structures for water control (delivery and discharge) and systems for the collection, reuse, treatment or disposal of drainage water. The preferred strategy to control salinity is to intercept drainage waters and utilise them beneficially before they reach and pollute surface or underground water bodies. When the drainage water quality is such that its potential for reuse is exhausted then it should be discharged to an appropriate outlet. Many different approaches can be combined for the satisfactory use of saline water. The appropriate combination depends on economic, climate, social factors factors and the hydrogeological setting of the region. In this report we briefly review some proposed salinity management strategies for the reuse of saline drainage water from irrigation and provide guidelines that should be considered in the regional selection of the sites for application of the Serial Biological Concentration method. Report Title Page 1

9 2. Management strategies for drainage water reuse Drainage water of sufficiently good quality might be used directly for crop production. However, poor quality drainage water needs certain management strategies. One option is to use it conjunctively with fresh water. Conjunctive use may involve blending drainage water with better quality water or drainage and fresh water can be used alternately termed cyclic use. In cyclic use, the two water sources can be rotated within the cropping season, or the two water sources can be used separately over the seasons for different crops. Another option is to sequentially use and reuse the drainage water to grow increasingly more salt tolerant crops while concentrating drainage to a manageable level. This practice is called sequential reuse or serial biological system (SBC). The choice of a particular reuse option depends largely on drainage water (quantity, quality and time of availability); crop tolerance to salinity; and availability of fresh water resources (for conjunctive use) Dual rotation cyclic management strategy Rhoades (1984a, b, and c) proposed the dual rotation cyclic management strategy which enhances the feasibility of reusing saline drainage water for irrigation. In this system, sensitive crops (lettuce, alfalfa, etc.) are irrigated with low salinity water (irrigation water supply), and salt- tolerant crops (cotton, sugar beets, wheat, etc.) are irrigated with saline drainage water or the shallow groundwater in the area. The secondary drainage resulting from such re-use could be used successively for crops of increasingly greater salt tolerance. The ultimate unusable drainage water is disposed of to an appropriate non polluting outlet. It should be noted that in this management strategy, the switch to saline water for the salt tolerant crops is usually made after seedling establishment, depending on the salinity of water; pre-plant irrigation and initial irrigation being made with better quality irrigation water. Where fresh waters are available for critical stages (germination and seedling), growers can take advantage of the fact that many crops are most salt sensitive during critical stages and much more tolerant during later growth stages. This flexible management is also good for long term feasibility of using drainage water as it keeps the soil from becoming excessively saline over the long run. The strategy was tested in a 20 ha field experiment on a commercial farm in California (Rhoades et al. 1989a, b, c). Two cropping patterns were tested. One was a 2-year rotation of wheat, sugar beets and melons. Colorado River water (900mg/l TDS) was used for pre-irrigation and early stages of wheat and sugar beets and for all irrigations of the melons. The remaining irrigations were with drainage water of 3500 mg/l TDS. No significant losses in the yields of the wheat or sugar beets occurred from substituting drainage water for Colorado River water after the initial stages and no significant yield loss was observed from growing melons in the land previously salinized from using drainage water. The estimated amounts of water consumed by the crops and lost as deep percolation are given in Table 1. These data show that the saline drainage water was successfully used for irrigation without resorting to high leaching. Soil salinity and sodicity in the seedbeds and rootzones were kept within acceptable limits for seedling establishment and the subsequent growth of the individual crops grown. These results along with the high crop yields and qualities obtained in this test under actual farming conditions support the credibility of the recommended cyclic, dual-rotation strategy to facilitate the use of saline waters for irrigation (Rhoades et al. 1989b). In this cyclic strategy, steady-state salinity conditions in the soil profile are never reached, since the irrigation water quality changes with crop type in the rotation and with time in the irrigation season. Consequently, a flexible cropping pattern which includes salt-sensitive crops can be achieved. The intermittent leaching which occurs using this strategy is more effective in leaching salts than is continuous leaching (i.e. imposing a leaching fraction with each irrigation). Another advantage of the strategy is that a facility for blending waters of different qualities is not required (Rhoades et al. 1992). Report Title Page 2

10 Table 1. Estimated evapotranspiration and deep percolation (inches) (after Rhoades et al. 1989b) Crop V a et V b iw V c dw LF d 1982 wheat s. beet melons wheat s. beet melons a Evapotranspiration estimated from pan evaporation and crop factors at Brawley, California. b Total amount of water applied for irrigation, c Estimate of deep percolation drainage water i.e. V iw - V et. d Estimate of leaching fraction, i.e. V dw /V iw. Some guidelines for selecting appropriate management practices are given by Rhoades et al. (1992). The most important management decision mentioned is crop selection. Crop tolerances to salinity are given in Tables A1-A3 (Appendix1). A list of other criteria that should be considered in the selection of crops for a reuse practice is given in Table 2. Table 2. Criteria to be considered for selecting crops for a reuse practice (after Grattan and Rhoades 1990) Selection criteria Desirable Undesirable Marketability high marketability low, unmarketable Crop salt tolerance tolerant sensitive Crop boron/chloride tolerant sensitive tolerance Potential to accumulate toxic element excluder toxic element accumulation toxic constituent Crop quality unaffected by saline water adversely affected by saline water Crop rotation consideration compatible incompatible Management/environmental conditions requirements Easy management, able to grow under diverse conditions Requires intensive management and can only be grown under very specific conditions The dual rotation cyclic management strategy presupposes the availability of two water sources; the saline drainage/ground water and less saline (fresh) irrigation supply water. Such reuse requires that the saline water be readily accessible for irrigation. A difficulty in adopting the cyclic, "dual-rotation" strategy may exist on small farms where the drainage water produced on-site is too little or does not coincide with peak crop-water demand and thus a storage system may be required to meet crop demands on-time. One method of collecting sufficient quantities of drainage water is to install a network of interceptor drains or to install a network of shallow wells in areas with shallow water table. A submersible pump could be placed in collector sumps as a means to access the drainage water. The size of the area that can be irrigated using such drainage water will vary depending on the capacity of the drainage system. If the flow rate needed for irrigation exceeds the drainage flow rate, storage reservoirs can be constructed for storing drainage water until its use is required. Rhoades et al. (1992) proposed application of the drainage reuse system in a regional context. They postulated that the long-term feasibility of using drainage water for irrigation would likely be increased if implemented on a regional scale such as shown in Figure 1, rather than on a farm scale. With regional management, certain areas in the region can be Report Title Page 3

11 dedicated to reuse. With progressively more saline drainage water, other dedicated reuse areas are irrigated where even more salt-tolerant crops are grown. Regional evaporation ponds or to treatment plants can be used for the final disposal of saline drainage water. Coordination and cost-sharing among growers will be required in such a regional reuse system (Rhoades et al. 1992). Figure1. Regional drainage water reuse plan (Rhoades et al. 1992) Under the cyclic strategy, soil salinity will fluctuate more than in soils irrigated with conventional water supplies. Management must be adjusted to keep the rootzone salinity levels within acceptable limits and long-term effects on soil salinization should be considered (Rhoades et al. 1992). Another concern in regards to the long-term feasibility of saline water reuse is that of soil permeability. Adverse effects are most likely to occur when irrigating with low-salinity water on soils previously irrigated with sodic, saline water. Such problems occurred at an experimental "reuse" site in California following pre-season rains and pre-irrigation with 0.3 ds/m water where sodic, saline water [9000 mg/l TDS; SAR = 30 (mmol c /l)½] had been used for irrigation for four previous years (Rolston et al. 1988). An impermeable, crusted soil was the result of this practice. Whether such a problem will occur or not, depends on whether the EC of the irrigation water is less than the threshold value, given the SAR of the irrigation water (Figure A2). The presence of carbonates and bicarbonates in the water could result in soil degredation in the long term because precipitation of calcium carbonate increases soil SAR. If the saline water contains certain elements, to levels that cause reduction in crop yield then toxicity may have more long-term detrimental effects than salinity. Thus long-term accumulation of potential toxicants in the soil must be considered. Water containing excessive concentrations of B or Cl should not be used to irrigate perennial crops (Rhodes et al. 1992). Report Title Page 4

12 Biofiltration is referred to a process where certain crops will accumulate large quantities of undesirable constituents (e.g. Se, Mo, NO 3, B, etc.) in the plants. A novel means of "treating" saline waste waters is to use them for irrigating those crops with biofiltration ability to help reduce adverse ecological effects of disposal. Cervinka et al. (1987) and Wu et al. (1987) have demonstrated the feasibility of this process. They found that mustard, and certain native plant species in California are effective in biofiltering and sequestering Se in their shoots. This practice is attractive where there is a potentially toxic trace constituent in the drainage water Sequential reuse of drainage water The reuse of drainage water on successively more salt-tolerant crops, referred to as sequential reuse (Drainage Reuse Technical Committee, 1999) or Sequential Biological Concentration (SBC) is another attractive water-management strategy for drainage and salt control. SBC is a management system that is based on the serial re-use of tile drainage effluent, cascading water through a series of crops with final containment in an evaporation basin. During the serial re-use cycle, the volume of effluent is reduced while the salinity increases, resulting in a relatively small volume of highly saline effluent for disposal in a small evaporation basin. In this system, higher-quality water is used to grow a salt-sensitive crop, and the drainage from this operation is collected by subsurface drains and subsequently used on a more salt-tolerant crop. This process is continued on progressively more salttolerant species until the final residual is collected and sent to evaporation ponds. Since substantial water is used as evapotranspiration at each stage, the drainage water volume available for irrigation is progressively reduced, while the salt concentration is correspondingly magnified. In California this system, called Integrated Farm Drainage Management (IFDM). In 2003, this novel system was being applied in California on some 63,000 ha, where it was part of IFDM program, (Khan et al., 2007). Figure 2 depicts the principles of a typical sequential reuse system. Figure 2. Principles of an IFDM system (Source: SJVDIP, 1999) Report Title Page 5

13 A typical IFDM system consists of four zones. In Zone 1, traditional salt sensitive crops are grown, e.g. vegetables, fruits, beans and corn. In Zone 2, traditional salt tolerant crops are grown, e.g. cotton, sorghum and wheat. In Zone 3, salt tolerant trees and shrubs are grown. In Zone 4, only halophytes can be planted. The final non-re-usable drainage water is discharged to a solar evaporator (SJVDIP, 1999). Figure 3 shows an example of IFDM from California and depicts the current layout of the 260-ha Red Rock Ranch. The ranch was waterlogged and salt affected and the farmer transformed it into an agroforestry reuse system. The shallow groundwater in some areas was within 30 cm of the land surface. The farmer planted rows of Eucalyptus camendulensis in the upslope boundary to intercept some of the lateral groundwater flow, and then tile drained the four parcels of land progressively. Within a few years of subsurface drainage, the land was reclaimed and vegetables were successfully grown in the non-saline parcels with imported irrigation water of 0.5 ds/m EC I. Cotton, sugar beets and salt tolerant grasses were grown successfully in the low-saline parcel using tile drainage water (EC I 6-8 ds/m) from the three non-salinezones. Because there were no opportunities for off-farm disposal of drainage waters in this area, the residual drainage water from this ranch was sequentially reused until no longer usable. A portion of the northeast zone has been set aside to irrigate saltgrass (EC I about ds/m) and the drainage water from saltgrass is used to irrigate Salicornia. The drainage water from the final stage (EC > 30 ds/m) is disposed into a solar evaporator to harvest salts. While about 75 percent of the land has been reclaimed sufficiently to grow salt sensitive cash crops, the remaining land is devoted to drainage water reuse by growing salt tolerant plants and harvesting salt. Figure 3. Layout of sequential reuse at Red Rock Ranch, California (Source: SJVDIP, 1999a) Report Title Page 6

14 Similar systems have been developed and tested in Australia (Blackwell et al. 2006). The Sequential Biological System (SBC) has been trialled at 2 sites in the Murray Darling Basin. One site at Griffith is at the municipal sewage treatment farm and involves a range of crops (e.g. maize, sunflower), trees and pastures. The other site is on an irrigated dairy property at Undera in northern Victoria, using a range of pasture, tree and shrub species. Both the Victorian and Griffith SBC systems have trialled fish farming in saline drainage water (saline aquaculture). The Undera system was able to grow several fish species at economically viable production levels. Figure 4 shows a schematic representation of an SBC system in Murrumbidgee Irrigation Area. This system can take drainage water, from the Murrumbidgee Irrigation Area, containing a mixture of salts and other pollutants through a series of six potentially productive cells or stages. This enables farmers and agricultural communities to potentially generate cash returns from wastewater flows, prior to discharge to evaporation basins (Balckwell et al. 2006). The theoretical design of the SBC system is based on application of irrigation drainage water with 1.2 ds/m salinity and adoption of a 33% leaching fraction. This, requires stage 2 to be irrigated with saline water at 3.6 ds/m and Stage 3 with 10.8 ds/m saline water. The drainage from Stage 3 is pumped directly into the Aquaculture cell at about 32.4 ds/m. The remaining components of a full SBC system can consist of non-vegetative biological and physical systems to further concentrate the salt, or provide a financial benefit. These systems include production of a range of aquatic species in ponds of varying salinities, salt gradient solar ponds to produce energy and evaporation basins to produce pure salts for industrial use and/or stockpiling for disposal, either by deep injection or perhaps transport to the sea (Blackwell et al. 2006). The field trialling (10.5 hectares) of the first three cells of a pilot SBC system demonstrated a capacity to manage the salts and other pollutants in saline wastewaters, through selected productive agricultural systems. The field data indicate that the progressive increase in salinity can be accommodated by using suitable cropping choices, although yields and financial returns diminished with increasing salinity. The cell with the highest salinity water (10.8 ds/m) was restricted to the production of halophytes. Significant reductions in other pollutants were achieved during flow through the first cell of the SBC system, with appropriate irrigation and drainage management (Blackwell et al. 2006). They suggested that further testing and economic analysis of the last three cells of the SBC system, the aquaculture, the solar pond and the salt production, as well as the whole integrated system is needed under Australian conditions. Report Title Page 7

15 Figure 4. Schematic Representation of Possible Layout, Flows and Concentrations of an SBC System designed to handle the winter drainage from the Murrumbidgee Irrigation area (After Blackwell et al. 2001). Jury (1975a) calculated the response time of tile-drained fields as a function of their drainage rates, drain spacing, and depth to barriers reducing or preventing downward flow, and found that it may take years to leach existing salt out of fields of the type found in the San Joaquin Valley, California. This delay time might substantially affect the performance of a system designed for water reuse or remediation of saline soil (Jury, 1975b). Jury et al. (2003) simulated a sequential reuse operation and concluded that drain lines primarily capture resident groundwater for decades or more after the operation starts and, especially if the barrier is at a substantial depth below the surface. As a result, the system will never reach steady state in any practical period of time. This was also noted by Ninghu et al. (2005) after simulating an experimental SBC site in Victoria where Saline groundwater (EC = 8.4 ds/m) was applied to blocks of red gums (Eucalyptus camaldulensis) and tall wheat grass. Simulations over a 10-year period highlighted that a large proportion of the applied saline drainage water escapes below the level of the tile drains, thus reducing the concentration effect of the trees and pasture. Much of the water intercepted by the tile drains under the site was resident groundwater, rather than leachate from underneath the crops. (Ninghu et al. 2005) also showed that increasing groundwater pressure from 100 to 150 cm below the surface doubled the drainage to the aquifer, while halving the amount of tile drainage (Table 3). Report Title Page 8

16 Table 3. Average water balances over 10-year period for tall wheat grass (Ninghu et al. 2005) Regional groundwater pressure(cm below surface) Rain (cm/year) Irrigation (cm/year) ET a (cm/year) Drainage to aquifer (cm/year) Tile drainage (cm/year) They concluded that SBC systems for the management of drainage effluent are unlikely to function effectively in areas with deep watertable levels and/or deep, permeable profiles underlain by aquifers. Large components of the leachate can by-pass the tile drains and escape to greater depths in the profile, thus making the systems operate poorly. According to Ninghu et al. (2005), a suitable site for SBC (in terms of soil profile) would be where tile drains are installed on top of an impermeable barrier at relatively shallow depth in the profile (about m below surface). 3. Regional site suitability criteria It is important to have an assessment of the irrigation areas where SBC can be implemented with little risk of damaging the environment. Not all areas in an irrigation region are suitable for SBC application and identification of the suitable areas requires multiple criteria analysis using GIS in a spatial context. If sufficient suitable areas can not be identified in a region, alternative disposal methods will be required for saline drainage waters from irrigated lands. In this section we will look at identifying areas in different irrigation regions in the (Murray Darling Basin (MDB) where SBC can be sited with minimum off-site effects and environmental risk. While it is difficult to accurately identify suitable locations on a regional basis, spatial data can be used to estimate the probability of finding suitable land (compared to the surrounding land) and its general location within a region. Of course in addition to this regional assessment, a detailed site investigation is required in order to decide whether a particular site will ultimately be suitable. Appropriate site selection is important to assure that the re use systems perform their functions in terms of salinity and long-term effects on soils and crops satisfactorily. The suitability of a site for SBC should be evaluated on the basis of criteria indicative of its potential to create conditions that deteriorate soil, and groundwater conditions. Factors to be considered include the effects of changes in salinity with time, the average salinity distribution in the root zone, interaction with climate variables (ET, rain), and the effects of different soil types. Relevant criteria for considering a site for SBC are primarily: soil salinity and permeability, groundwater depth and its salinity. As well as considering the relevant criteria for siting an SBS system, the dynamic and interactive effects of all criteria must be considered. Groundwater flow system dynamics are also important in when considering the potential for leakage into regional aquifers. Sinclair Knight Mertz 2004, established irrigation development risks and guidelines for the Murray-Darling Basin based on biophysical attributes and threshold values in a risk assessment framework (Table 4). These biophysical thresholds identify potential major and minor risks and identify where new developments are not permissible. Environmental factors considered important in this risk assessment are soil type, groundwater salinity, watertable depth and rate of rise, rate and quality of water applied for irrigation. These threshold values are also valuable in assessing the sustainability of sites in terms of salinity and reuse. Report Title Page 9

17 Table 4. Some irrigation development risk assessment triggers In assessing land suitability for application of SBC, there are a number of criteria to consider.: Firstly, what is the depth to groundwater? This determines the storage available beneath the site. Secondly, what is the quality of the groundwater below the site? Thirdly, the groundwater gradient and permeability of the aquifer determine the rate of movement from the site itself. In making this evaluation the following criteria has been used: - The extent of shallow watertable conditions - The extent of fine textured soils - The presence of soil salinity - The extent of high salinity groundwater These criteria were included for SBC site selection in order to select those sites where saline groundwater disposal is already a problem and SBC might offer an effective saline effluent Report Title Page 10

18 management option. Limiting the criteria to the sites with current or potential salinity problems would reduce the risk of spreading salinity to other unaffected areas in the region. A Geographical Information Systems (GIS) based approach was used in regional suitability analysis, using estimates of thresholds for SBC suitability criteria in two irrigation areas (Murrumbidgee Irrigation Area -MIA and Shepparton Irrigation Region -SIR) both in the MDB. The main aim of the analysis is to provide a coarse scale ranking of the relative suitability of land for SBC application within regions. Here we only considered the main physical factors for defining the suitability thresholds. Socio-economic factors associated with SBC application such as loss of land, proximity to roads and facilities have not been considered in this analysis. In this study, GIS was used in each region to display high resolution layers of spatial data (e.g. groundwater depths, salinity, and soils data). Among the benefits of using a geographic information system (GIS) to solve problems is its ability to easily store, retrieve, query, manipulate, copy, and display spatial and attribute information. With the spatial data projected, it is possible to view and interpret this information and create a consistent basis on which to identify thresholds and assess risk. The GIS facilitates risk assessment by making it easier to consider different environmental factors. Maps that displayed hazards for each environmental factor were developed to view the results. The provision of information in this manner is seen as highly advantageous, as the distribution of environmental risks can readily be identified and they also provide supporting information to decision-making. Also revisions can be easily captured as additional information on risk assessment becomes available. Khan, 2001 adopted a multiplication index for SBC suitability that uses GIS-based data of groundwater depth, groundwater quality and soil texture. The multiplicative factor (F mpf ) is given in Equation (1). F mpf = F gwd *F gwq *F st (1) Where F gwd = the groundwater depth index which is 0 if the watertable depth is more than 3m, 5 for depths between 1.5 and 3m and is 10 if the watertable is shallower than 1.5m (Table 5). F gwq = the groundwater quality index which is 0 if the groundwater salinity (EC) is less than 1.5 ds/m, 5 for groundwater salinity between 1.5 and 3 ds/m and is 10 for groundwater salinity greater than 3 ds/m (Table 6). F st = soil suitability index and is 0 for the mountainous and hilly regions/soils, 1 for sandy soils, 5 for flooded, 7 for loamy soils and 10 for salt affected and clay soils (Table 7). F mpf = The multiplicative SBC factor ranging from marginal (0-245) to extremely suitable ( ) (Table 8). Table 5. Groundwater depth index (F gwd ) classes for the multiplicative SBC factor (Khan 2001) Groundwater depth (m Fgwd < >3.0 0 Report Title Page 11

19 Table 6. Groundwater quality index (F gwq ) classes for the multiplicative SBC factor (Khan 2001) Groundwater quality, EC (ds/m) Fgwq < >3 10 Table 7.Soil type suitability index (F st ) for the multiplicative SBC factor (Khan 2001) Soil Type Fst Mountains and hilly soils 0 Sandy Soil 1 Flooded Soil 5 Loamy Soil 7 Salt-affected and clay soils 10 Table 8. The multiplicative SBC factor (F mpf ) (Khan 2001) Category F mpf Description Extremely Suitable Highly Suitable Suitable Marginal Here we modified the multiplicative SBC factor (F mpf ) to include soil salinity as a risk factor as well as changing the threshold values for other indices. The new proposed SBC suitability factor (F sbc ) is based on the previous work on the SBC suitability factors in Pakistan (Khan 2001) and threshold values for irrigation sustainability in MDB (Table 4). The new risk factors are groundwater depth, groundwater salinity, soil salinity, and soil hydraulic conductivity. Tables 9-13 summarize the threshold values for each of these indices. Table 9. Groundwater depth Index (F gwq ) Groundwater depth (m) Groundwater Index < >4.0 0 Report Title Page 12

20 Table 10. Groundwater Quality Index (F gwq ) Groundwater salinity-ec (ds/m) Groundwater quality Index > <2 0 Table 11. Soil Salinity Index (F ss ) Soil salinity (ds/m) Soil Salinity Index > <0.5 0 Table 12. Soil Permeability Index (F st ) Soil K (m/d) Soil Permeability Index <= >1.5 0 Based on the above indices the following classification for the overall SBC suitability (F sbc ) is proposed for in this study. F sbc = F gwd *F gwq *F st * F ss (2) The above proposed indices can be calculated for irrigation areas using watertable depth, salinity and soils data in a GIS environment. The overall SBC suitability Index is then a combination of all individual indices used to identify areas suitable for application of SBC on a regional map (Table 13). Report Title Page 13

21 Table 13. Proposed SBC Suitability Index (Fsbc ) Category F sbc Description 1 >5000 Extremely Suitable Highly Suitable Suitable Marginal Groundwater flow system data is another layer of information that should be used in conjunction with the SBC Suitability Index to assess how the local or regional groundwater system behaves in confining the salinity effects of the probable SBC sites to the surrounding areas. Similar assessments have been carried out using simulation modelling for the SBC site in Griffith (Khan et al. 2001; David and Khan 2001). Long-term sustainability of the system can best be studied by simulation modelling of the specific sites using data on soils, crops, watertable depths and salinities. 4. Application of the suitability criteria in Irrigation Areas Spatial data were obtained from CSIRO Land and Water for groundwater depth and salinity of the Murrumbidgee Irrigation Area (MIA) and the Shepparton Irrigation Area (SIR). Measured soil hydraulic property data for SIR were obtained from DPI Victoria on 34 sites and were linked to the soils map according to each soil type. Suitability thresholds were defined separately for each of the physical factors (groundwater depth and salinity, soils hydraulic conductivity and salinity), and assigned to classes (0-10) which were then combined to derive a number of suitability classes ranging from extremely suitable (Fsbc >5000) to not suitable (Fsbc <525) Murrumbidgee Irrigation Area Study area Murrumbidgee Irrigation Area (MIA), part of the Murrumbidgee catchment, is in southeast Australia and forms the eastern part of the Murray-Darling Basin (Figure 5). It is located about 600 Km southwest of Sydney and 900 km east of Adelaide. Irrigation development took place in the MIA between 1906 and Water was supplied by the first major Australian reservoir built for irrigation Burrinjuck Dam. During its 90-year history, this flat landscape has allowed the Murrumbidgee Irrigation Area to become a large integrated re-use system with downstream water users receiving a mixture of river water and drainage water from the upstream irrigation area. The development of irrigation farming over this time has altered the natural environment-vegetation, fauna and landscape from a semi-arid pastoral district to a vibrant irrigation area. Rice-growing started in the MIA in 1924, although rapid development of rice areas only took off in the 1970s and 1980s. Of the total area of 230,222 ha, rice has been the most dominant land use with a maximum planting in 2001 of 184,384 ha. Recent drought condition has decreased the area under rice. Other land use includes cereals/ oil seeds, horticulture (especially citrus and winegrapes), pasture and vegetables. The MIA consists of the Yanco, Mirrool, Benerembah, Wah Wah and Tabbita irrigation districts. The natural drainage-way of the MIA is the Mirrool Creek. The topography is a flat Report Title Page 14

22 open plain at an elevation of m above sea level. Water for the MIA is diverted from the Murrumbidgee River at Berembed Weir and further downstream at Gogeldrie weir. From Berembed Weir water moves into Bundidgery storage which is the start of the system owned and maintained by Murrumbidgee Irrigation Ltd. Water is distributed and measured onto farm properties and farmers pay for the water supply charges. From Gogeldrie Weir water is directed to the Sturt canal to supply farms on the western side of the MIA. Drainage water from irrigation farms flows through Mirrool Creek which is a natural drainage system discharging to Barren Box Swamp and then flows into the districts of Benerembah, Tabbita and Wah Wah (Figure 5). Figure 5. Location map of the Murrumbidgee Irrigation Area (MIA) Soils The soils (0-5 m depth) in the MIA consist of more than 90 different soil types, and have been mapped in the Murrumbidgee Irrigation Area (MIA) (Hornbuckle and Christen, 1999; Stannard, 1970; Taylor and Hooper, 1938; van Dijk, 1958; 1961). These soils are generally grouped into five distinct groups due to similarity in hydraulic characteristics: Clays - self mulching and hard setting (non self mulching clays)-these soils either consist of crumbly calcareous shallow horizons (self mulching) or hard setting non-calcareous surface soils (non self mulching clays). The hydraulic conductivity of the top horizons of self mulching Report Title Page 15

23 clays (up to 0.5 m depth) is normally high (around 30 mm/day) whereas the hydraulic conductivity for deeper horizons (1.5 to 3 m) is relatively low (0.5 to 1mm /day). The reported hydraulic conductivity values for shallow non-self mulching clays are around 4 mm/day. Red-Brown Earths - this group of soils consists of loamy or sandy surface horizons of more than 0.1 m depth which abruptly change to clay subsoils. The reported hydraulic conductivity values for this soil group vary greatly between 58 mm/day to 1039 mm/day. Transitional Red Brown Earths these soils have hydraulic characteristics of clays and red brown earths. The top clay layer is very shallow ( m). The deeper profiles contain lime and gypsum. The reported hydraulic conductivity of these soils in the m depth ranges between to 10 mm/day. Sands over clay these soils mainly consist of sandy top soils (0.1 to 0.6 m) with a dense sub clay soils. The hydraulic conductivity of some of the soils of this group is greater than 100 mm/day. Deep sandy soils these soils are of aeolian origin and contain coarse sands to a depth of 4 meters. The hydraulic conductivities for this soil group may be greater than 1000 mm/day. Spatial distribution of soil groups in the MIA is given in Appendix 3 (Figure A-3) Climate The climate of Murrumbidgee Irrigation Area is classified as semi-arid, characterised by hot summers and mild winters. The average annual rainfall lies between 256 mm to 609 mm with the long term average of 406 mm. Evapotranspiration exceeds rainfall in the summer months from November to April and average rainfall is close to average evapotranspiration rates during the winter months of June and July (~35mm/month). Recent drought has contributed to low local rainfall and extreme evapotranspiration conditions over the irrigation season. These conditions increased crop water use and evaporation from water bodies and extended the irrigation season Hydrogeology The Murrumbidgee Irrigation Area is located on the fluvial plains created by the Murrumbidgee River. The relief is generally flat with the average height below 200 m AHD The groundwater body extends through the sequence of unconsolidated sediments that comprise three major aquifer systems: Shepparton, Calivil and Renmark underlain by the Palaeozoic bedrock (Khan et al. 2002). Shepparton Aquifer System The Shepparton aquifer system comprises a series of aquitard layers (Punthakey et al., 1994). Lithology of the aquifer system comprises interconnected fine to coarse Layers and it is basically unconfined. The material is not well sorted and aquifers are thin comparing to deeper beds in the aquifer system. Calivil Aquifer System This aquifer system underlies the Shepparton and is characterised by high yield potential achieved during water extraction.the water quality of the thick sand and gravel deposits of this formation is generally good- EC ~ 2.3 ds/m in the Griffith area (Punthkey et al.,1994). Renmark Aquifer System Report Title Page 16

24 The aquifer in this formation lies 150 m below the surface. The water quality declines to approximately 3 ds/m Groundwater salinity The shallow Shepparton sediments were deposited by a series of prior streams over several million years. Below the Shepparton formation (20 to 60 meters thick), the Calivil aquifer systems often extends to depths greater than 150 meters. Water movement through the deep aquifers is generally from east to west except in the area with major groundwater pumping around Darlington Point. Recharge to the deep aquifers is mainly from the Murrumbidgee River downstream of Narrandera and from the irrigation areas. The salinity increases from east to west, but is generally low. Deep groundwater with low salinity levels (<0.5 ds/m) occur over a large area extending between Narrandera and Hay. The shallow Shepparton aquifer is often very saline especially under the irrigation areas (Figure A-4) where salinity levels can be high (e.g ds/m). Deep bore yields may exceed 400 L/s from depths of 90 to 250 meters. The Lower Murrumbidgee Alluvium has been estimated to have 250,000,000 ML of low- salinity groundwater in storage. In the last 10 years local imbalance between groundwater recharge and discharge has resulted in around meters residual drawdown in deep aquifers over large areas between Darlington Point and Hay Suitable SBC sites Figures 6-9 show the distribution of different environmental factors (watertable depth, salinity, soil hydraulic conductivity) as indecies for SBC suitability in the MIA. Suitability thresholds were defined separately for each of the physical factors and assigned to classes (0-10), according to tables These were then combined to derive a number of suitability classes ranging from extremely suitable (>5000) to not suitable (<525) according to table 13. Report Title Page 17

25 Figure 6. Map of groundwater depth index (Table 9) in MIA Report Title Page 18

26 Figure 7. Map of the soil permeability index (Table 12) in MIA Report Title Page 19

27 Figure 8. Map of groundwater salinity index (table 10) in MIA Report Title Page 20

28 Figure 9. Soil salinity index (Table 11) in MIA Report Title Page 21

29 Figure 10 shows the spatial map of the final SBC suitability criteria for the MIA. Figure 10. Map of the SBC suitability- new criteria (F SBC -Table 13) in the MIA As can be seen in figure 10, most of the land in the MIA is marginally suitable; mostly because of watertable depth restriction in the suitability criteria for SBC application (i.e. areas Report Title Page 22

30 with watertable depth greater than 4m are not suitable and between 2-4m marginally suitable). Areas in the north and east of the region show more suitable areas for SBC. It should be noted that some extremely suitable areas that show on the map (Figure 10) might have other restrictions such as the slope or high elevation (areas around Yenda, for example) which restrict the use of the land as a communal SBC area. Conversely, some areas west of the region might be suitable based on restriction of groundwater movement and high existing salinity which are not shown as a result of this analysis and because of deep watertable as a limiting factor. Any decisions on setting up an SBC area should be based on further analysis considering potential groundwater movement and other factors such as economics, accessibility, topography, soil profile (e.g. depth to impermeable layer) and other factors discussed in this report. The current analysis only considers four biophysical criteria that were thought to be most important in a regional assessment. For comparison purposes, an analysis has also been carried out where the multiplicative SBC factor (Equation 1) was calculated for MIA according to the criteria in tables (5-8). Figure 11 gives final multiplicative SBC suitability map of the MIA which shows most of the area being marginally suitable and only the areas in the north and east being more suitable for the SBC application. The addition of the soil salinity as an index for the suitability seems to have caused inclusion of a few parcels of land as suitable areas. Overall the areas suitable for the SBC application seem to be similar with both suitability criteria in a regional context, with some differences in the north central parts (Figures 10 and 11). Report Title Page 23

31 Figure 11. Map of SBC suitability (multiplicative) factor in the Murrumbidgee Irrigation Area. Report Title Page 24

32 4.2. Shepparton Irrigation Region The Shepparton Irrigation Region (SIR) covers more than 500,000 hectares or one third of the Goulburn Broken Catchment and the eastern area of the North Central Catchment (Figure 12). The irrigated area of 317,000 ha uses 1.5 million megalitres of water a year and in had a gross value of production of about $5.5 billion. The main primary industries are horticulture, dairying, cropping, viticulture, wool, forestry and grazing. The Shepparton Irrigation Area (SIA) is located in the Golburn Murray Water (G-MW) area of operations in northern Victoria and is part of the whole SIR which consists of Rochester, Central Goulburn, SIA and the Murray Valley irrigation areas ( Figure 12). Irrigated horticultural and dairy are the key drivers of the Shepparton regional economy. Indeed, the Shepparton region is often referred to as the Food Bowl of Australia as around 25% of the total value of Victoria s agricultural production is generated in this area. The irrigation sector supports a host of secondary industries, in the Shepparton region, including food processing, equipment manufacturing and transport. In terms of the area irrigated, dairying is the most common enterprise and is concentrated in the central and northern areas of the district. Figure 12. Irrigation areas in the Shepparton Irrigation Region Report Title Page 25

33 Climate Average annual rainfall in the region is berween 380 and 500mm, spread throughout the year, and average annual Class A pan evaporation is 1350mm Soils The Shepparton area is part of an extensive alluvial plain within the Murray Basin. This basin was formed by massive land subsidence during the Tertiary period and began to fill with sediments. The dominant sediments in the area were deposited by an older river system ('prior stream' system) in the Quaternary period. These deposits are called the Shepparton Formation on geological maps and are mainly derived from rivers and streams but also include aeolian (i.e. windblown) deposits. These aeolian deposits consist of fine calcareous soil material which spread over much of Northern Victoria during drier climatic periods. The Shepparton Formation deposits vary from about 50 to 125 metres in depth across much of the Northern Victorian plains and cover the older alluvial (Tertiary) and marine sediments. The prior stream landscape is a complex array of relic stream lines. The soil types have developed on or near prior streams and are highly variable. The SIR has a wide range of soil types. Detailed soil maps for the SIR were developed during the period from 1942 to 1964 and mostly feature 6 major soil groups, made up of 148 soil types. The soil groups were designed primarily to provide an indication of the crop suitability of soils. For example, Group 1 was considered suitable for horticultural crops, and Groups 2 and 3 for pasture and shallow-rooting crops. The region has a variety of soils ranging from sandy to heavy clay soils. Most of the soils are duplex, characterised by a shallow Horizon A of mm and a restricting layer at or below the interface of Horizons A and B Groundwater and salinity in the Shepparton Irrigation Region The Shepparton Irrigation Region is very much like a basin that has been filled up with fine and coarse sediment over thousands of years. The riverine plains of the Shepparton Irrigation Region are alluvial deposits having a comparatively flat surface. More recent ancestral streams deposited sediments over the top of the deep lead materials and bedrock. In these sediments, deposits of coarse material (aquifers) are separated by less permeable clayey materials. Aquifers occur at all depths in these sediments. These underground waterbearing layers of sand or gravel are capable of supplying significant quantities of water to bores or springs. Water quality in these aquifers becomes poorer with depth. An extensive network of unconfined aquifers, ranging from near surface to 420 m beneath the ground, occurs within the Shepparton Irrigation Region. The main aquifers are found within the first 25 m. These are generally pumped for irrigation, stock and domestic use. The confined Deep Lead system commonly found around the Murray-Valley area refers to groundwater stored at depths between m. Following land clearing and introduction of irrigation in the region, about 100 years ago, watertables have risen from about 20m to a few meters below the surface mobilizing the salt in the profile. The quality of the groundwater is varied across the region. Good quality groundwater is found in Murray Valley east, areas surrounding Shepparton and Nathalia as well as the western region of the SIR. High salinity groundwater is found around Tongala, Kyabram, Stanhope and Tatura. These areas require careful management of water when used for irrigation and stock and domestic purposes. Much of the groundwater that can be pumped in the Shepparton Irrigation Region is not suitable for irrigation and requires mixing with another water source. This dilution is necessary to minimise the hazards associated with using straight saline groundwater on pasture productivity and soil health. Generally speaking, due to the relatively low salinity status of soils in much of the region, the need for rehabilitation of saline land is low, hence the focus has been mostly on prevention (pumping of groundwater and mixing with fresh channel water) to date. However, there have been a few examples where rehabilitation works have successfully restored production Report Title Page 26

34 where groundwater salinity is over 5 ds/m and safe reuse becomes more difficult. For example, the Girgarre evaporation basin project developed in the 1980's was able to restore and improve productivity to some 400 hectares of salt affected irrigation land. Another is the Undera SBC project (discussed below) that has researched the productive use of higher salinity groundwater at a badly salt affected site Suitable SBC sites For the purpose of identifying suitable areas for the SBC application in the region, environmental factors identified in tables 9-13, were mapped using GIS for the whole region. Spatial data were obtained from CSIRO Land and Water for groundwater depth and salinity of the SIR. Measured soil hydraulic properties and soil salinity data for SIR were obtained from DPI Victoria on 34 sites and were linked to the soils map according to each soil type. Each factor was then grouped into classes according to the suitability criteria (table 6-9). Figures show the result of this classification for watertable depth, groundwater salinity, soil hydraulic conductivity, and soil salinity. While figure 14 shows a large portion of the area suitable in terms of the watertable depth (index >=5), the groundwater salinity index (Figure 13) shows a limited area suitable (index>=5). When soil suitability criteria are introduced, figure 14 shows almost no restriction because of low hydraulic conductivity of the soils in the region (index >=5 corresponding to Ks< 0.2 m/day). But introduction of soil salinity, as a suitability criterion, changes the picture (Figure 15) as all the area has soil salinity less than the minimum threshold of 0.5 ds/m. Assigning a value of 0 to the soil salinity index caused the overall SBC suitability index to be 0 according the Equation 2 and no area in the region is shown to be suitable (Figure 16). The low salinity of the soils (both A and B horizons) might be the result of leaching the surface soils with less saline water (averaging ~ 0.06 ds/m) in the Goulburn River (Smith et al. 1983). In order to avoid the restriction of soil salinity imposed by equation 2, there is a possibility of assigning weights to different physical factors in equation 2 and defining a new suitability factor based on weighted values of each factor. Another option is to consider the multiplicative factor (F mpf in equation 1) which does not include soil salinity. We have applied the latter option for comparing the results of the two suitability factors (i.e. F mpf vs F sbc ). Figure 17 shows the result of applying this option to the data in SIR. As expected, relaxing the soil salinity restriction, resulted in a map showing the south and west part of the region ( mostly in Rochester and Shepparton area) as being potentially suitable to highly suitable areas for SBC application (F mpf >500). These are the areas with shallow saline groundwater. The results of applying these SBC criteria to both irrigation areas are summarized in Table 14, with the multiplicative criteria (in Table 8) being summarized for SIR. It should be noted that this analysis is coarse and at the regional level. Any decision on whether a particular site is suitable for SBC application requires a detailed site investigation. Table 14. Areas (ha) with different suitability for SBC application in MIA and SIR Suitability class MIA SIR Criteria used Table 13 Table 8 Not suitable-marginal Suitable Highly Suitable Extremely Suitable Report Title Page 27

35 Groundwater salinity index Figure 13. Map of groundwater salinity in the Shepparton Irrigation region Report Title Page 28

36 Figure 14. Map of groundwater depth index for SIR Report Title Page 29

37 10 Soil salinity index 0 Figure 15. Soil salinity index in SIR Report Title Page 30

38 SBC suitability index 0 Figure 16. SBC suitability index for SIR Report Title Page 31

39 Figure 17. Map of SBC multiplicative factor in SIR Report Title Page 32

40 5. Conclusions While SBC is one way of managing saline drainage water from irrigation areas, there is a need for guidelines for suitable site selection for an SBC operation. Four biophysical factors related to possible environmental impact of SBC application, namely, water table depth and salinity, soil salinity and hydraulic conductivity were considered in a spatial framework. Thresholds for these factors were identified considering risk assessment in irrigation areas. A multiplicative index for regional SBC suitability considering these factors is proposed that is simple to implement. Application of the method in two irrigation areas in the Murray darling Basin has identified some suitable areas in the MIA, but none in the SIR. The multiplicative formulation of the proposed index is believed to be a restrictive factor if any of the environmental indices are below the threshold criteria (i.e. giving a numerical value of zero to the index). In the MIA, areas suitable for SBC application are mostly in the north east part of the region indicating the limiting watertable condition (deeper than 4m) in the west part. In SIR, the low salinity of the soils (probably because of leaching) caused the overall suitability index to be nil all over the region. The soil salinity index can be relaxed for this region to consider suitable areas with three other indices. Doing this has resulted in identifying some suitable areas in the Goulburn Valley Irrigation Area and some in Rochester Irrigation Area. The proposed multiplicative index, in its current form, considers all four environmental factors to be equally important in making decision on the suitability of land. One way of improving the method would be to consider different weights to different factors depending on the anticipated impacts. The weightings can also be assigned different values across irrigation areas based on our understanding of each region. Whilst the proposed guidelines and thresholds can be useful in identifying suitable areas in a coarse regional context, more in-depth study of the environmental factors are needed for specific site selection. Modelling the dynamics of water and salt movement at potential sites is the recommended method to study the long term effects of the SBC application on the surrounding environment. Report Title Page 33

41 Appendices Appendix 1. Salt tolerance of crops Table A1. Salt tolerance of herbaceous crops 1 (after Maas 1986) Crop Electrical conductivity of Rating 4 saturated soil extract Common name Botanical name 2 Threshold 3 ds/m slope %/ds/m Fibre, grain & special crops Barley 5 Hordeum vulgare T Bean Phaseolus vulgaris S Broadbean Vicia faba MS Cotton Gossypium hirsutum T Cowpea Vigna unguiculata MT Flax Linum usitatissimum MS Groundnut Arachis hypogaea MS Guar Cyamopsis tetragonoloba T Kenaf Hibiscus cannabinus MT Maize 6 Zea mays MS Millet, foxtail Setaria italica MS Oats Avena sativa MT* Rice, paddy Oryza sativa S Rye Secale cereale T Safflower Carthamus tinctorius MT Sesame 8 Sesamum indicum S Sorghum Sorghum bicolor MT Soybean Glycine max MT Sugarbeet 8 Beta vulgaris T Sugarcane Saccharum officinarum MS Sunflower Helianthus annuus MS* Triticale X Triticosecale T Wheat Triticum aestivum MT Wheat (semidwarf) 10 T. aestivum T Wheat, Durum T. turgidum T Grasses & forage crops Alfalfa Medicago sativa MS Alkaligrass, Nuttall Puccinellia airoides T* Alkali sacaton Sporobolus airoides T* Barley (forage) 5 Hordeum vulgare MT Bentgrass A. stolonifera palustris MS Bermudagrass 11 Cynodon dactylon T Report Title Page 34

42 Bluestem, Angleton Dichanthium aristatum MS* Brome, mountain Bromus marginatus MT* Brome, smooth B. inermis MS Buffelgrass Cenchrus ciliaris MS* Burnet Poterium sanguisorba MS* Canarygrass, reed Phalaris arundinacea MT Clover, alsike Trifolium hybridium MS Clover, Berseem T. alexandrinum MS Clover, Hubam Melilotus alba MT* Clover, ladino Trifolium repens MS Clover, red T. pratense MS Clover, strawberry T. fragiferum MS Clover sweet Melilotus MT* Clover, white Dutch Trifolium repens MS* Cowpea (forage) Vigna unguiculata MS Dallisgrass Paspalum dilatatum MS* Fescue, tall Festuca elatior MT Fescue, meadow F. pratensis MT* Foxtail, meadow Alopecurus pratensis MS Grama, blue Bouteloua gracilis MS* Hardinggrass Phalaris tuberosa MT Kallargrass Diplachne fusca T* Lovegrass 12 Eragrostis sp MS Maize (forage) 6 Zea mays MS Milkvetch, Cicer Astragalus cicer MS* Oatgrass, tall Arrhenatherum, Danthonia Oats (forage) Avena sativa MS* Orchardgrass Dactylis glomerata MS Panicgrass, blue Panicum antidotale MT* Rape Brassica napus MT* Rescuegrass, blue Bromus unioloides MT* Rhodesgrass Chloris gayana MT Rey (forage) Secale cereale MS* Ryegrass, Italian Lolium italicum multiflorum Ryegrass, perennial L. perenne MT Saltgrass, desert Distichlis stricta T* Sesbania Sesbania exaltata MS Sirato Macroptilium atropurpureum Sphaerophysa Sphaerophysa salsula MS Sudangrass Sorghum sudanense MT MS* MT* MS Report Title Page 35

43 Timothy Phleum pratense MS* Trefoil, big Lotus uliginosus MS Trefoil, birdsfoot narrowleaf L. corniculatus tenuifolium MT Trefoil, broadleaf L. corniculatus arvenis MT birdsfoot 13 Vetch, common Vicia angustifolia MS Wheat (forage) 10 Triticum aestivum MT Wheat, (forage) Wheatgrass, crested Wheatgrass, crested Wheatgrass, intermediate Durum stand, fairway T. turgidum MT Agropyron sibiricum MT A. cristatum T A. intermedium MT* Wheatgrass, slender A. trachycaulum MT Wheatgrass, tall A. elongatum T Wheatgrass, western A. smithii MT* Wildrye, Altai Elymus angustus T Wildrye, beardless E. triticoides MT Wildrye, Canadian E. canadensis MT* Wildrye, Russian E. junceus T Vegetables & fruit crops Artichoke Helianthus tuberosus MT* Asparagus Asparagus officinalis T Bean Phaseolus vulgaris S Beet, red 8 Beta vulgaris MT Broccoli Brassica oleracea botrytis MS Brussel sprouts B. oleracea gemmifera MS* Cabbage B. oleracea capitata MS Carrot Daucus carota S Cauliflower Brassica oleracea botrytis MS* Celery Apium graveolens MS Cucumber Cucumis sativus MS Eggplant Solanum melongena esculentum Kale Brassica oleracea acephala Kohlrabi B. oleracea gongylode MS* Lettuce Lactuca sativa MS Maize, sweet Zea mays MS MS MS* Report Title Page 36

44 Muskmelon Cucumis melo MS Okra Abelmoschus esculentus S Onion Allium cepa S Parsnip Pastinaca sativa S* Pea Pisum sativum S* Pepper Capsicum annuum MS Potato Solarium tuberosum MS Pumpkin Cucurbita pepo pepo MS* Radish Raphanus sativus MS Spinach Spinacia oleracea MS Squash, scallop Cucurbita pepo melopepo MS Squash, zucchini C. pepo melopepo 1 33 MT Strawberry Fragaria sp S Sweet potato Ipomoea batatas MS Tomato Lycopersicon lycopersicum MS Turnip Brassica rapa MS Watermelon Citrullus lanatus MS* 1 These data serve only as a guideline to relative tolerances among crops. Absolute tolerances vary, depending upon climate, soil conditions and cultural practices. 2 Botanical and common names follow the convention of Hortus Third where possible. 3 In gypsiferous soils, plants will tolerate EC e s about 2 ds/m higher than indicated. 4 T = Tolerant, MT = Moderately Tolerant, MS = Moderately Sensitive and S = Sensitive. Ratings with an* are estimates. 5 Less tolerant during seedling stage, EC e at this stage should not exceed 4 or 5 ds/m. 6 Grain and forage yields of DeKalb XL-75 grown on an organic muck soil decreased about 26% per ds/m above a threshold of 1.9 ds/m. 7 Because paddy rice is grown under flooded conditions, values refer to the electrical conductivity of the soil water while the plants are submerged. Less tolerant during seedling stage. 8 Sesame cultivars, Sesaco 7 and 8, may be more tolerant than indicated by the S rating. 9 Sensitive during germination and emergence, EC e should not exceed 3 ds/m. 10 Data from one cultivar, "Probred". 11 Average of several varieties. Suwannee and Coastal are about 20% more tolerant, and common and Greenfield are about 20% less tolerant than the average. 12 Average for Boer, Wilman, Sand and Weeping cultavars. Lehmann seems about 50% more 13 Broadleaf birdsfoot trefoil seems less tolerant than narrowleaf. Table A2. Salt tolerance of woody crops 1 (after Maas 1986) Crop Common name Electrical conductivity of saturated soil extract Botanical name 2 Threshold 3 ds/m slope %/ds/m Almond 5 Prunus duclis S Apple Malus sylvestris S Rating 4 Report Title Page 37

45 Apricot 5 Prunus armeniaca S Avocado 5 Persea americana S Blackberry Rubus sp S Boysenberry Rubus ursinus S Castorbean Ricinus communis MS* Cherimoya Annona cherimola S* Cherry, sweet Prunus avium S* Cherry, sand P. besseyi S* Currant Ribes sp. S* Date palm Phoenix dactylifera T Fig Ficus carica MT* Gooseberry Ribes sp. S* Grape 5 Vitis sp MS Grapefruit 5 Citrus paradisi S Guayule Jojoba 5 Parthenium argentatum Simmondsia chinensis T Jujube Ziziphus jujuba MT* Lemon 5 Citrus limon S Lime C. aurantiifolia S* Loquat Eriobotrya japonica S* Mango Mangifera indica S* Olive Olea europaea MT Orange Citrus sinensis S Papaya 5 Carica papaya MT Passion fruit Passiflora edulis S* Peach Prunus persica S Pear Pyrus communis S* Persimmon Diospyros virginiana S* Pineapple Ananas comosus MT* Plum; prune 5 Prunus domestic a S Pomegranate Punica granatum MT* Pummelo Citrus maxima S* Raspberry Rubus idaeus S Rose apple Syzygium jambos S* Sapote, white Casimiroa edulis S* Tangerine Citrus reticulata S* 1 These data are applicable when rootstocks are used that do not accumulate Na + or Cl - rapidly or when these ions do not predominate in the soil. 2 Botanical and common names follow the convention of Hortus Third where possible. 3 In gypsiferous soils, plants will tolerate EC e s about 2 ds/m higher than indicated. 4 T = Tolerant, MT = Moderately Tolerant, MS = Moderately Sensitive and S = Sensitive. Ratings with an* are estimates. T Report Title Page 38

46 5 Tolerance is based on growth rather than yield. Table A3. Salt tolerance of ornamental shrubs, trees and ground cover 1 (after Maas 1986) Common name Botanical name Maximum permissible 2 EC e ds/m Very sensitive Star jasmine Trachelospermum jasminoides 1-2 Pyrenees cotoneaster Cotoneaster congestus 1-2 Oregon grape Mahonia aquifolium 1-2 Photinia Photinia fraseri 1-2 Sensitive Pineapple guava Feijoa sellowiana 2-3 Chinese holly, cv. Burford Ilex cornuta 2-3 Rose, cv. Grenoble Rosa sp. 2-3 Glossy abelia Abelia grandiflora 2-3 Southern yew Podocarpus macrophyllus 2-3 Tulip tree Liriodendron tulipifera 2-3 Algerian ivy Hedera canariensis 3-4 Japanese pittosporum Pittosporum tobira 3-4 Heavenly bamboo Nandina domestica 3-4 Chinese hibiscus Hibiscus rosa-sinensis 3-4 Laurustinus, cv. Robustum Viburnum tinusm 3-4 Strawberry tree, cv. Compact Arbutus unedo 3-4 Crape Myrtle Lagerstroemia indica 3-4 Moderately sensitive Glossy privet Ligustrum lucidum 4-6 Yellow sage Lantana camara 4-6 Orchid tree Bauhinia purpurea 4-6 Southern Magnolia Magnolia grandiflora 4-6 Japanese boxwood Buxus microphylla var. japonica 4-6 Xylosma Xylosma congestum 4-6 Japanese black pine Pinus thunbergiana 4-6 Indian hawthorn Raphiolepis indica 4-6 Dodonaea, atropurpurea cv. Dodonaea viscosa 4-6 Oriental arborvitae Platycladus orientalis 4-6 Thorny elaeagnus Elaeagnus pungens 4-6 Spreading juniper Juniperus chinensis 4-6 Pyracantha, cv. Graberi Pyracantha fortuneana 4-6 Report Title Page 39

47 Cherry plum Prunus cerasifera 4-6 Moderately tolerant Weeping bottlebruch Callistemon viminalis 6-8 Oleander Nerium oleander 6-8 European fan palm Chamaerops humilis 6-8 Blue dracaena Cordyline indivisa 6-8 Spindle tree, cv. Euonymus japonica 6-8 Grandiflora Rosemary Rosmarinus officinalis 6-8 Aleppo pine Pinus halepensis 6-8 Sweet gum Liquidamabar styraciflua 6-8 Tolerant Brush cherry Syzygium paniculatum >8 3 Ceniza Leucophyllum frutescens >8 3 Natal palm Carissa grandiflora >8 3 Evergreen pear Pyrus kawakamii >8 3 Bougainvillea Bougainvillea spectabilis >8 3 Italian stone pine Pinus pinea >8 3 Very tolerant White iceplant Delosperma alba >10 3 Rosea iceplant Drosanthemum hispidum >10 3 Purple iceplant Lampranthus productus >10 3 Croceum iceplant Hymenocyclus croceus > Species are listed in order of increasing tolerance based on appearance as well as growth reduction. 2 Salinities exceeding the maximum permissible EC e may cause leaf burn, loss of leaves, and/or excessive stunting. 3 Maximum permissible EC e is unknown. No injury symptoms or growth reduction was apparent at 7 ds/m. The growth of all iceplant species was increased by soil salinity of 7 ds/m. Report Title Page 40

48 Appendix 2. Threshold values for reduction in infiltration rate of soils FIGURE A-2. Relative rate of water infiltration as affected by salinity and SAR (Source: Ayers and Westcot 1985) Report Title Page 41

49 Appendix 3. Spatial data Figure A-3. Spatial distribution of soil groups in MIA. Report Title Page 42