Salt water tolerant plants

Living along the coast certainly has its advantages: access to the beach every day, coastal breezes, mild temperatures, fresh seafood and pretty views.

However, gardening in these environments can present a challenge. While saltwater has its benefits, most plants and flowers don’t like it. Salinity in the soil inhibits a plant’s ability to absorb important nutrients, thereby disrupting the plant’s metabolism.

Finding salt tolerant plants to for your lawn can be a challenge. In many cases, you can select salt tolerant varieties of ceratin plants which can do well in coastal climates. The salt tolerance of plants is determined by a variety of factors, including a plant’s ability to grow under and resist high winds, salt spray, alkaline soils and infertile, sandy soils.

When choosing plants that will be placed facing the ocean without buildings to protect them, you should choose highly salt tolerant plants. If the plants are protected by a building, you can get away with selecting types that are only slightly salt tolerant.

Keep reading for recommendations on salt tolerant shrubs, salt tolerant perennials, salt tolerant plants for beach landscaping and even ideas for salt tolerant tropical plants.

Salt Tolerant Shrubs

Salt tolerant shrubs can deliver a big impact, depending on how big they get. Finding a variety that you love can transform your yard into a beautiful oasis.

Oleander is a favorite shrub for coastal living. Not only are oleanders salt tolerant, but also they are heat tolerant, survive in full sun and thrive in a variety of soils while producing beautiful blooms. Different varieties can grow to a height of 10 feet and 8 feet wide, so they can cover a large area for just one plant.

Other highly salt tolerant shrubs that like sun or part shade include these varieties:

  • Century Plant (Agave americana)
  • Natal Plum (Carissa macrocarpa)
  • Pampas Grass (Cortaderia selloana)
  • Prickly Pear (Oputnia ficus-indica)
  • Thorny Olive (Elaeagnus pungens)
  • Dwarf Yaupon Holly (Ilex vomitoria)
  • New Zealand Flax (Phormium tenax)
  • Pittosporum and Dwarf Pittosporum (Pittosponrum tobira)
  • “Majestic Beauty” Indian Hawthorn (Rhaphiolepis umbellata)
  • Rugosa Rose, Rosemary (Rosa rugosa, Rosmarinus officinalis)
  • Butcher’s Broom (Ruscus aculeatus)
  • Sandwanka Viburnum (Viburnum suspensum)
  • Yucca (Yucca gloriosa, Yucca aloifolia)

If part of your yard is sheltered from the wind and the sand that comes with it, you can try incorporating some moderately salt tolerant species into your landscape. The following shrubs are moderately salt tolerant:

  • Agarito (Mahonia trifoliolata)
  • Sago Palm (Cycas revoluta)
  • Japanese Aucuba and Dwarf Aucuba (Aucuba japonica, Aucuba japonica ‘Nana’)
  • Hedge Bamboo (Bambusa multiplex)
  • Wintergreen Barberry (Berberis julianae)
  • Bottlebrush (Callistemon rigidus)
  • Flowering Quince (Chaenomeles speciosa)
  • Sweet Pepperbush Clethra and Dwarf Sweet Pepperbush Clethra (Clethra alnifolia; Clethra alnifolia ‘Hummingbird’, ‘White Doves’ and ‘Sixteen Candles’)
  • Fragrant Daphne (Daphne odora)
  • Japanese Euonymus (Euonymus japonicus)
  • Fatsia (Fatsia japonica)
  • Pineapple Guava (Feijoa sellowiana)
  • Forsythia (Forsythia x intermedia)
  • Rose of Sharon (Hibiscus syriacus)
  • Bigleaf Hydrangea (Hydrangea macrophylla)
  • ‘Carissa’ Holly (Ilex cornuta ‘Carissa’), ‘Rotunda’ Holly (Ilex cornuta ‘Rotunda’), ‘Needlepoint’ Holly (Ilex cornuta ‘Needlepoint’) and Inkerry Holly (Ilex glabra)
  • Chinese Juniper (Juniperus chinesis)
  • Texas Sage (Leucophyllum frutescens)
  • Japanese Privet (Ligustrum japonicum)
  • Leatherleaf Mahonia (Mahonia bealei)
  • Firethorn Pyracantha (Pyracantha coccinea)
  • Indian Hawthorne (Rhaphiolepis indica)
  • Southern Indica Azalea Varieties and Satsuki Azaleas (Rhododendron ‘Formosa’, ‘George Tabor’ and ‘G.G. Gerbing’; Rhododendron ‘Gumpo’ series)
  • Stinking Viburnum (Viburnum odoratissimum)
  • Adam’s Needle Yucca (Yucca filamentosa)

If you only need slightly salt tolerant shrubs, you can look for these plants at your local garden center:

  • Abelia (Abelia x grandiflora)
  • ‘Brilliant’ Chokeberry (Aronia arbutifolia ‘Brilliantissima’)
  • Japanese Barberry (Berberis thunbergii)
  • Butterfly Bush (Buddleia davidii)
  • American Beautyberry (Callicarpa americana)
  • Japanese Camellia and Sasanqua Camellia (Camellia japonica, Camellia susanqua)
  • Gardenia (Gardenia jasminoides)
  • Winterberry (Ilex verticillata)
  • Banana Shrub (Michelia figo)
  • Nadina Heavenly Bamboo (Nandina domestica)
  • Dwarf Nandina (Nandina domestica ‘Firepower’, ‘Harbor Belle’ and ‘Moon Bay’)
  • Tea Olive Osmanthus (Osmanthus fragrans, Osmanthus x fortune)
  • Double Reeves Spirea (Spirea cantoniensis ‘Lanceata’)
  • Cleyera (Ternstroemia gymnanthera)
  • Walter’s Viburnum (Virburnum obvatum)
  • Tinus Viburnum Laurustinus (Viburnum tinus)
  • Weigela (Weigela florida)

Thinking you may prefer something smaller? Let’s move onto perennials.

Salt Tolerant Perennials

Perennials can add color to a yard that is typically dominated by its green grass. There are just a few highly tolerant flowers, such as the Blanket Flower Gaillardia, Daylily, Lantana, Prickly Pear Cactus, Lavender Cotton and Seaside Goldenrod. When you are making your selections, just keep in mind other important factors in your yard, such as the amount of sun the area gets, as well as how much water the plants need.

If you can give your flowers some protection, these moderately salt tolerant perennials would work well:

  • Fern Leaf Yarrow (Achillea filipendulina)
  • Common Yarrow (Achillea millefolium)
  • Agapanthus (Agapanthus africanus)
  • Sea Thrift (Ameria maritima)
  • Butterfly Weed (Ascelpias tuberosa)
  • Asparagus Fern (Asparagus densiflorus ‘Sprengeri’)
  • Crinum Lily (Crinum varieties)
  • Mexican Heather (Cuphea hyssopifolia)
  • Hardy Ice Plant (Delosperma cooperi, Delosperma nubigenum)
  • Cheddar Pinks Dianthus (Dianthus gratianopolitanus)
  • Hummingbird Plant (Dicliptera suberecta)
  • Firebush (Hamelia patens)
  • Hardy Ginger Lily (Hedychium varieties)
  • Candytuft (Iberis sempervierns)
  • Red False Aloe (Hesperaloe parviflora)
  • Turk’s Cap (Malvaviscus drummondii)
  • Nippon Daisy (Nipponanthemum nipponicum)
  • Seashore Mallow (Kosteletzkya virginica)
  • Firecracker Plant (Russelia equisetiformus)
  • Purple Heart (Setcreasia pallida)
  • Hen and Chicks (Sempervivum tectorum)
  • Society Garlic (Tulbughia violacea)

If your flowers will be protected from the ocean by a wall or another structure, you can choose one of the following slightly salt tolerant plants for your garden:

  • Angel’s Trumpets (Brugmansia)
  • Canna Lily (Canna varieties)
  • Holly Fern (Cyrtomium falcatum)
  • Golden Dewdrop (Duranta erecta)
  • Purple Coneflower (Echinacea purpurea)
  • Hardy Hibiscus (Hibiscus moscheutos, Hibiscus coccineus)
  • Hosta (Hosta varieties)
  • Red Hot Poker (Kniphofia varieties)
  • Daffodil (Narcissus)
  • Blue Jasmine Leadwort (Plumbago auriculata)
  • Dwarf Mexican Petunia (Ruellia brittoniana ‘Katie’)
  • Autumn Sage (Salvia greggii, Salvia microphylla)
  • Princess Flower (Tibouchina urvilleana)
  • Common Thyme Verbena (Thymus vulgaris)

Looking to put it all together? Now, let’s talk about beach landscaping ideas.

Salt Tolerant Plants for Beach Landscaping

In addition to all the salt tolerant plants we have listed about, you’ll probably also want to think about turf grasses, groundcovers, vines and trees. All of these types of plants thrive better than flowers in these environments.

Turfgrasses such as Seashore Paspalum have a very high salt tolerance and moderate drought tolerance and prefer sunny conditions. Hybrid and Common Bermuda, as well as Zoysia grasses, all have a high salt and drought tolerance, which is one reason you tend to see them in coastal areas.

If you are in search of a salt tolerant groundcover, you might consider trying:

  • Asparagus Sprengeri Fern (Asparagus densiflorus)
  • Algerian Ivy (Hedera canariensis)
  • Goats-foot Morning Glory (Ipomea pes-caprae)
  • Trailing Lantana (Lantana montevidensis)
  • Virginia Creeper (Parthenocissus quinquefolia)
  • Stonecrop (Sedum varieties)
  • Asiatic Jasmine and Confederate Jasmine (Trachelospermum asiaticum, Trachelospermum jasminiodes)
  • Wedelia (Sphagneticola trilobata)
  • Shore Blue Pacific Juniper (Juniperus conferta)
  • Lily Turf Liriope (Liriope muscari)
  • Japanese Purpleleaf Honeysuckle (Lonicera japonica ‘Purpurea’)
  • Mondo Grass (Ophiopogon japonicus)

Vines, which can sometimes serve as groundcover can help add color to your outdoor areas. If you have an idea which would work well for this type of plant, you might consider:

  • Virginia Creeper (Parthenocissus quinquefolia)
  • Cape Honeysuckle (Tecoma capensis)
  • Bougainvillea (Bougainvillea varieties)
  • Trumpet Vine (Campsis radicans)
  • English Ivy (Hedera helix)
  • Coral Honeysuckle (Lonicera sempervirens)
  • Fig Ivy/Creeping Fig (Ficus pumila)
  • Carolina Jessamine (Gelsemium sempervirens)

English Ivy needs shade, so if you opt for this plant, make sure it isn’t in full sun.

If you’d like to add height or shade to your yard, you might want to add a tree which can tolerate salty conditions. A few we suggest are:

  • Chinaberry Texas Umbrella (Melia azedarach)
  • Huisache (Vachellia farnesiana)
  • Texas Persimmon (Diospyros texana)
  • Southern Golden Raintree (Koelreuteria bipinnata)
  • Mulberry (Morus alba)
  • Mesquite (Prosopis glandulosa)
  • Lavender Chaste Tree Vitex (Vitex agnus-castus)
  • Camphor Tree (Cinnamomum camphora)
  • Citrus (Cleopatra mandarin)
  • Loquat (Eriobotrya japonica)
  • Retama (Parkinsoia aculeata)
  • Japanese Black Pine (Pinus thunbergii)

Large Trees, including the Australian Pine, Tamarisk Salt Cedar, Deodar Cedar, Arizona Cypress, Live Oak, Eucalyptus, Cottonwood and Bald Cypress also do well along the beach. Of course, if you want to go with a typical tropical landscape, then the Palmetto, Texas Palmetto, Cabbage or Florida Palmetto, Washington Fan Palm, Pindo Palm, European Fan Palm and Phoenix or Canary Island Date Palm work well along our Texas beaches.

If you have an area that gets hit with strong winds or experiences a good amount of sea spray, you might want to consider adding Sea Coast Blue Stem, Salt Grass, Lindheimer’s Muhly Grass, Sand Knotgrass, Fountain Grass and Giant Seaoats to your lawn and garden.

Salt Tolerant Tropical Plants

If you want a more tropical look for your landscaping, you have plenty of options. You will still need to take into account which types are shade tolerant and which plants need sun, depending on the conditions in the area you want to plant.

Palms are the most obvious addition to turn your property into a tropical oasis. Whether it’s a large Sabal Palmetto or a smaller Saw Palmetto, these plants are adapted to flourish in coastal areas.

Ornamental grasses like the Sand Cordgrass work well along the coast when paired with Oleander, Bougainvillea and some of the perennials below. A combination of these plants can help you create a pretty tropical escape.

Tropical perennials that do well at the beach include:

  • Wright’s Texas Firecracker (Anisacanthus wrightii)
  • Purple Milkweed (Asclepias purpurascens)
  • Cast-iron plant (Aspidistra elatior)
  • Various Angel’s Trumpets (Brugmansia) varieties, including “Betty Marshall”, “Double White”, “Charles Grimaldi”, “Cherub”, “Snowbank”, “Sunset”, “Intrigue”, “Lemon Punch”, “Minerva”, “Orange Punch” and “Pacific Beauty”
  • Several Canna (Canna x generalis) varieties, such as “Bengal Tiger”, “Blueberry Sparkler”, “Chocolate Sunrise”, “Ermine”, “Flaming Kabobs”, “Phasion” and “Pink Sunburst”
  • Louisiana Canna (Canna glauca), specifically the “Karin” and “Panache” varieties
  • The “Red Stripe” Wild canna lily (Canna indica)
  • Several varieties of Crinum lily (Crinum americanum), including “Elizabeth Traub”, “Ellen Bosanquet”, “Infusion”, “Li’l Stinker”, “Parfait”, “Persephone”, “Peyton’s Place”, “Pink Trumpet”, “Sangria”, “Super Ellen” and “Wading Pool”
  • The “Schreck” species of Milk and Wine Lily (Crinum x herbertii)
  • King’s Cross (Dicliptera suberecta)
  • Four varieties of Garland Flower (Hedychium coronarium); (“Anne Bishop”, “Daniel Weeks”, “Kin Ogi” and “Vanilla Ice”)
  • “Applecourt” and “Slim’s Orange” types of Scarlet Ginger Lily (Hedychium coccineum)
  • “Prayer Flags” variety of Kahili Ginger (Hedychium urophyllum)
  • “Anna’s Red” type of Lenten Rose (Helleborus orientalis)
  • “Red Silver” version of Stinking hellebore (Helleborus foetidus)
  • Over one dozen Hellebore (Helleborus x hubridus) varieties
  • Four Day Lily (Hemerocallis) varieties: “August Flame”, “Autumn Minaret”, “Freewheelin’” and “Steeple Jackie”
  • Red yucca (Hesperaloe parviflora)
  • “Swamp Angel”, “Cranberry Crush”, “Fantasia”, “Fireball”, “Heartthrob” and “Midnight Marvel” Texas star hibiscus (Hibiscus coccineus) varieties
  • China rose (Hibiscus rosa-sinensis) varieties, including “Raspberry Rose”, “Flora Plena”, “Peppermint Flare”, “Robert Fleming” and “Summer Storm”
  • “Voodoo” variety of Amaryllis lily (Hippeastrum puniceum)
  • A dozen Hosta varieties
  • “Dick Weaver” and “Dunbar Creek” types of Garden phlox (Phlox Paniculata) varieties
  • “Chi chi” variety of the Mexican petunia (Ruellia brittoniana)
  • The “Ragin’ Cajun” Red ruellia (Ruellia elegans)
  • The “Amistad” type of Sage (Salvia)
  • Mealy blue sage (Salvia farinacea)
  • Autumn sage (Salvia greggii)
  • Chinese windmill palm (Trachycarpus fortunei)
  • August rain lily (Zephyranthes candida)

Another option is to use containers for your landscaping so that you can bring these plants inside to control the salinity of the soil. By using this approach, you can have the flexibility to use lower salt tolerant alternatives to what species might work well in other areas. You can also change the salinity of the soil or build a fence or other barrier to help protect the plants to increase the variety of plants you may choose for your beachside home.

ABC Knows Coastal Lawns

Finding plants that thrive in our coastal environment can be a challenge. If you have a brown thumb or just need a second opinion on how to turn your yard into an oasis, contact the professionals at ABC Home & Commercial Services. Our experienced lawn care technicians can assist you in creating outdoor spaces that will remain healthy in our conditions here in Corpus Christi.

What’s a Mangrove? And How Does It Work?

If you’ve ever spent time by the sea in a tropical place, you’ve probably noticed distinctive trees that rise from a tangle of roots wriggling out of the mud. These are mangroves—shrub and tree species that live along shores, rivers, and estuaries in the tropics and subtropics. Mangroves are remarkably tough. Most live on muddy soil, but some also grow on sand, peat, and coral rock. They live in water up to 100 times saltier than most other plants can tolerate. They thrive despite twice-daily flooding by ocean tides; even if this water were fresh, the flooding alone would drown most trees. Growing where land and water meet, mangroves bear the brunt of ocean-borne storms and hurricanes.

AMNH

There are 80 described species of mangroves, 60 of which live exclusively on coasts between the high- and low-tide lines. Mangroves once covered three-quarters of the world’s tropical coastlines, with Southeast Asia hosting the greatest diversity. Only 12 species live in the Americas. Mangroves range in size from small bushes to the 60-meter giants found in Ecuador. Within a given mangrove forest, different species occupy distinct niches. Those that can handle tidal soakings grow in the open sea, in sheltered bays, and on fringe islands. Trees adapted to drier, less salty soil can be found farther from the shoreline. Some mangroves flourish along riverbanks far inland, as long as the freshwater current is met by ocean tides.

One Ingenious Plant

How do mangroves survive under such hostile conditions? A remarkable set of evolutionary adaptations makes it possible. These amazing trees and shrubs:

  • cope with salt: Saltwater can kill plants, so mangroves must extract freshwater from the seawater that surrounds them. Many mangrove species survive by filtering out as much as 90 percent of the salt found in seawater as it enters their roots. Some species excrete salt through glands in their leaves. These leaves, which are covered with dried salt crystals, taste salty if you lick them. A third strategy used by some mangrove species is to concentrate salt in older leaves or bark. When the leaves drop or the bark sheds, the stored salt goes with them.
  • hoard fresh water: Like desert plants, mangroves store fresh water in thick succulent leaves. A waxy coating on the leaves of some mangrove species seals in water and minimizes evaporation. Small hairs on the leaves of other species deflect wind and sunlight, which reduces water loss through the tiny openings where gases enter and exit during photosynthesis. On some mangroves species, these tiny openings are below the leaf’s surface, away from the drying wind and sun.
  • breathe in a variety of ways: Some mangroves grow pencil-like roots that stick up out of the dense, wet ground like snorkels. These breathing tubes, called pneumatophores, allow mangroves to cope with daily flooding by the tides. Pneumatophores take in oxygen from the air unless they’re clogged or submerged for too long.
Roots That Multitask

Root systems that arch high over the water are a distinctive feature of many mangrove species. These aerial roots take several forms. Some are stilt roots that branch and loop off the trunk and lower branches. Others are wide, wavy plank roots that extend away from the trunk. Aerial roots broaden the base of the tree and, like flying buttresses on medieval cathedrals, stabilize the shallow root system in the soft, loose soil. In addition to providing structural support, aerial roots play an important part in providing oxygen for respiration. Oxygen enters a mangrove through lenticels, thousands of cell-sized breathing pores in the bark and roots. Lenticels close tightly during high tide, thus preventing mangroves from drowning.

Ready-to-Roll Seeds

The mangroves’ niche between land and sea has led to unique methods of reproduction. Seed pods germinate while on the tree, so they are ready to take root when they drop. If a seed falls in the water during high tide, it can float and take root once it finds solid ground. If a sprout falls during low tide, it can quickly establish itself in the soft soil of tidal mudflats before the next tide comes in. A vigorous seed may grow up to two feet (about 0.6 m) in its first year. Roots arch from the seedling to anchor it in the mud. Some tree species form long, spear-shaped stems and roots while still attached to the parent plant. After being nourished by the parent tree for one to three years, these sprouts may break off. Some take root nearby while others fall into the water and are carried away to distant shores.

A World Traveler

Botanists believe that mangroves originated in Southeast Asia, but ocean currents have since dispersed them to India, Africa, Australia, and the Americas. As Alfredo Quarto, the head of the Mangrove Action Project, puts it, “Over the millions of years since they’ve been in existence, mangroves have essentially set up shop around the world.” The fruits, seeds, and seedlings of all mangrove plants can float, and they have been known to bob along for more than a year before taking root. In buoyant seawater, a seedling lies flat and floats fast. But when it approaches fresher, brackish water—ideal conditions for mangroves—the seedling turns vertical so its roots point downward. After lodging in the mud, the seedling quickly sends additional roots into the soil. Within 10 years, as those roots spread and sprout, a single seedling can give rise to an entire thicket. It’s not just trees but the land itself that increases. Mud collects around the tangled mangrove roots, and shallow mudflats build up. From the journey of a single seed a rich ecosystem may be born.

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Mangroves are survivors, due to elaborate root systems that sprawl above and below the waterline. These so-called walking trees coolly shrug off extreme heat and muddy topsoil deficient in oxygen and filter the salty waters of southern Florida and tropical Southeast Asia, where the majority of the 73 known mangrove species live. Mangroves also help other species survive, forming dense forests that shelter monkeys, kangaroos, and tigers as well as shellfish and brightly colored corals. Even humans benefit as impoverished coastal communities exploit the tree for food, lumber, and medicine. But mangrove forests are dwindling. Relentless deforestation and powerful tropical storms have reduced their habitats by 35 percent (pdf) since 1980, prompting ecologists to step up their investigations into the unique ability of mangroves to survive and protect their coastal environments.

iStockphoto

Slows Coastal Erosion Following the Indian Ocean tsunami of 2004, a study led by Danish ecologist Finn Danielsen reported that coastal areas flush with mangrove trees were markedly less damaged than those without. The findings suggest that the trees shield the coastline (pdf) by reducing the height and energy of ocean waves and offer hard evidence that deforestation could result in increased coastal damage from storms.

Captures Carbon Mangroves are expert carbon scrubbers. A global inventory by McGill University environmental scientist Gail Chmura found that mangroves pack away carbon faster than terrestrial forests. Every year they hoard some 42 million tons, roughly equivalent to the annual carbon emissions of 25 million cars.

Establishes Deep Roots The mangrove depends on its complex root system for stability, oxygen, and salt filtration. In 2007 U.S. Geological Survey scientists analyzing mangrove roots and soil up to 8,000 years old found that during periods of rising sea level, the roots grow faster and bolster the soil, which helps hoist the tree upward.

Survives Extreme Heat Mangroves love sunshine. Unlike many tropical plants that close the pores on their leaves at midday to reduce sun exposure, mangroves remain active, absorbing heat to prevent evaporation of the shallow waters they depend on. They also curb their thirst: A 30-foot mangrove sips about six gallons per day, while a similar-size pine tree guzzles more than three times that amount.

Are there any crops that can be irrigated by salt water?

Asked by: Sarah Tawton, Liverpool

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Most plants would be killed by salt water irrigation, but there are a few that would thrive. One, which has the potential to become a cash crop, is the pink-flowering seashore mallow (Kosteletzkya virginica), which grows wild in the coastal marshlands of the southeastern United States. Researchers from the University of Delaware are calling it “the saltwater soybean”, because its seeds contain oils that are similar in composition and quantity to those produced by soybean plants.

Researchers in China have now introduced it to the heavy saline soils of Jiangsu Province, where the area of saline mudflats has been increasing year by year. They believe it has the potential to improve the soil, as well as to form a basis for the development of ecologically sound saline agriculture. Another plant with similar potential is the dwarf glasswort (Salicornia bigelovii), which has been evaluated for growth with seawater irrigation in a harsh desert environment – and with great success, producing at least as much nutritious edible oil as conventional soybean and sunflower crops.

  • Why don’t we use desalination technology to provide drinking water?
  • Why do mimosa plants close when touched?

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Saltwater Incursion

Jerry Coleby-Williams

JERRY COLEBY-WILLIAMS: This is the story of salt. What it does to our plants and how gardeners can adapt. I’m on the edge of Moreton Bay in Brisbane, a perfect place to show you what I mean.

This park is just across the road from the bay and a few weeks ago this area was inundated by a king tide. In fact the water was knee deep and marine fish were feeding in this area. And until recent rains, saltwater encrusted this soil white. This park is a laboratory for the varied affects of salt on plants.

This mango tree is in very good health and yet not thirty metres away is another mango tree, exactly the same age but with a very different story to tell.

This tree is displaying classic symptoms of salt water damage. The crown is thin. It’s trying to re-grow, but subsequent king tides are killing off the regrowth. The bark is beginning to split, even limbs are starting to fail and there’s secondary problems. There’s fungal decay and borer. This tree is going to die.

Most of the crops and ornamentals we grow are not adapted to salty conditions. For these plants, when water in the soil is fresh, it is absorbed by their roots. But when water in the soil contains more dissolved minerals than their sap, instead of entering their roots, water is drawn out. So these plants can be literally standing in saltwater and yet they’re experiencing an artificial drought.

Salty conditions are not confined to our coasts. If you live in a heavily cleared landscape, such as the Murray Darling, dry land salinity is widespread. And there are naturally salty soils – sodic soils around Adelaide. Now while it’s easy to be confronted in our laboratory by the negative impacts of salt, there’s also some plants which are growing really well. They’re adapted to saline soils.

Australia is blessed with a wide range halophytes – that is, plants that are adapted to salty soils. And this fern here, it’s the Mangrove Fern, it’s one of the few ferns that are adapted water and it grows really well in fresh soil with fresh water as well. But this verdant grass down here is a beautiful thing. This is Saltwater Couch, sometimes called ‘Saltine.’ Now this makes a wonderful lawn grass in a salty soil.

I’m walking through a grove of she-oaks. These are beautiful trees. They’ve got wonderful bark, a graceful form and you can hear them sighing in the breeze. There are so many different species, there’s one for every situation in Australia. But right now I’m feasting my eyes on this Tuckeroo. This is a medium sized tree and I’ve seen them growing further south than Sydney and you quite often see them growing in fissures in rock, so they don’t need a deep soil. They take salt water really well. But the thing I like about them best is that while this is a medium-sized tree, if you’re prepared to prune and shape them from a young tree, you can fit them in to a very small garden. And they’re so fresh when they come out into new leaf. It’s a delightful shade of green.

Other plants that are thriving here in our laboratory include the Swamp Lily, a fast growing, lush bulb that produces large white flowers in summer. And there’s Portulaca. There’s large flowered varieties which make great summer annuals, and this wild form can be used just like spinach. And the Beach Hibiscus. This can be trained either as a shade tree or as a hedge. It’s very adaptable.

We’ve seen there’s a range of ornamentals that can cope with salt. But what if you’re a vegetable grower? Well as it happens, my grandad had a very nice trick. To four and a half litres of water, he’d add one tablespoon full of salt and once a fortnight, he’d water these vegetables – Cabbage, Kale, Kohlrabi, beetroot, Mangle-wurzel, silverbeet, New Zealand spinach and asparagus. And the result was he got really luscious, leafy crops. And the reason this trick works is because the ancestors of all these modern crops came from a maritime climate. They’re partly adapted to salt.

None of these vegetables will thrive if you’ve got salty, clay soil. Salt disperses clay, making it sticky and gluey. Now there is a solution – you add gypsum. A handful per square metre once or twice a year and you work it in. Now the other solutions for growing on salty soil – you know these because we tell you every week. You add plenty of compost into your soil and you make sure your beds are freely draining. Raise them if you can. If you can’t raise them, then just grow plants in ridges.

So you can see that gardening with salt isn’t a death sentence. It’s a question of choosing the right plants and adapting the way you garden.

STEPHEN RYAN: Jerry’s dead right. As gardeners we need to stay on our toes and learn to adjust to changing conditions.

Now if you want to know more about Jane’s visit to Steel’s Creek and how the garden’s going, check out the June issue of the Gardening Australia Magazine. And if you want to know more about next week’s program, stay just where you are.

Next week, it’s Sophie’s guide to drought tolerant plants – what to select and how to grow them.

And to some they’re Roly Poly’s, to others, Pill Bugs, Slaters or Wood Lice. Josh calls them pests and he shows how to control them.

JOSH BYRNE: As organic gardeners, we don’t want to eradicate. Firstly, that’s simply not possible and secondly, they do have a role to play. We need to manage them.

STEPHEN RYAN: I guarantee you’ll enjoy next week’s program, so I’ll see you then.

Using saline water for irrigation

How does salt affect the plant?

Plant roots generally take up moisture by a type of osmosis through membranes in root cells.

Osmosis is a natural process where water, passing through a semi-permeable membrane, moves from a solution of low levels of dissolved salts to one with a higher salt level.

This process allows water to move from a solution of relatively low concentration (the irrigation water) into a solution of relatively high concentration (in the plant root cells) in an attempt to establish equilibrium in the two solutions.

This continues until the plant cells become full, or turgid.

Moderately saline water

If the irrigation water is moderately saline, the plant has to work harder to absorb water from the soil.

With lack of water, the plant soon begins to wilt, and growth is slowed, with reduced yields.

Highly saline water

If highly saline irrigation water is used, the process of osmosis can become reversed. Where the solution outside the plant roots is higher in salt concentration than that of the root cells, water will move from the roots into the surrounding solution.

The plant loses moisture, and so suffers stress.This is why symptoms of high salt damage are similar to those from high moisture stress:

  • leaf tip dieback
  • margins yellowing, scorched and turning brown or black, followed by
  • leaf fall of dead leaves.

If water is sprayed directly on leaves, it can cause salt scorch and leaf damage even at lower salinities.

Another danger: specific ion toxicity

Irrigation water is only moderately saline, but if it contains high concentrations of specific ions, it can still damage the crop.

  • High chloride or sodium ion levels (the most common) cause symptoms similar to high salinity.
  • High bicarbonate levels can make calcium and magnesium unavailable to the plant.
  • Some effluent waters that may be used for irrigation can have high boron levels.

Acceptable salinity levels

There will be some variation in how salinity affects the plant, depending on crop, variety, rootstock, leaching ability of the soil and also method of irrigation (spray, drip or furrow).

Most crops, including salt-sensitive crops, should accept salinity levels of up to 700 µS/cm without loss of yield. (See How salinity is measured).
With salinities over 700 µS/cm, we could expect to see reduced yields from some salt-sensitive plants.
The water salinity levels acceptable to each crop (that is, the levels that do not affect crop yields), and levels that will cause about 10% loss of yield.

Acceptable salinity levels for horticulture

Using the table on fruit crops (Table 2), for example, we see that most grapevines should accept salinity levels of up to 1000 µS/cm without loss of yield. Above this figure, yields generally start to decline, and we could expect up to 10% yield loss at 1700 µS/cm.

Acceptable salinity levels for pasture

Similarly, using the table on forage crops (Table 4), we would expect lucerne, for example, to accept salinity levels of up to 1300 µS/cm without loss of yield. Above this figure, yields generally start to decline, and there might be up to 10% yield loss at 2200 µS/cm.

Soils and salinity

High salt levels in soils also reduce yield.

High levels of sodium from common salt can also, over time, damage soil structure, causing

  • surface crusting
  • reduced infiltration
  • restricted subsoil drainage and root development in ‘blocky’ soils.

Soils with high proportions of sodium are known as sodic soils.

Management options for saline irrigation water

For horticultural crops

  • Rootstocks: Choosing saline-resistant rootstocks in new plantings can minimise the detrimental effect of salinity. (See comment on grapevines.)
  • Mulching: As saline water evaporates from the soil it leaves behind salts. A good mulch under the crop helps reduce surface evaporation, maintains moisture near the soil surface and lessens the build-up of soil salinity.

Monitoring salinity levels

If you have a regular irrigation water salinity problem, you must have a meter for monitoring salinity levels.

Small hand-held meters are readily available at reasonable cost. Calibrate meters against a known buffer solution at least twice each season, as all meters tend to drift in accuracy over time. This calibration is a simple procedure: the meter should come with instructions for this.

Using leaching

The main method of reducing the effect of saline water is to apply extra water to leach salts below the rootzone.

Water with an EC as low as 800 µS/cm will add over ½ tonne of salt for each megalitre of water applied. At this rate, unless leaching and drainage occurs, soil salinity may quickly increase to unsustainable levels.

Leaching often occurs with rainfall. In other cases, irrigation water beyond the crop’s water requirement may need to be applied.

The extra irrigation water needed to leach salts is termed the leaching fraction, and this can be calculated for various crops and soil types.

The formula for determining the minimum leaching requirement (MLR) is:

MLR = ECWA÷

where

  • ECWA is the EC of the available irrigation water
  • ECWY % is the salinity level of the irrigation water that results in a specified percentage yield loss.

Example: Say we needed to use water with an EC of 1800 µS/cm. We are prepared to accept a 10% yield loss, and we know that water of 1700 µS/cm (1.7 dS/m) EC would cause this (acceptable) yield loss.

MLR = 1.8 ÷ = 0.16

This means that, in this example, 16% more water (than is strictly required by the crop) should be applied when irrigating.

Note on drainage: If you apply additional leaching water, you must have good subsoil drainage to ensure the leached saline water can regularly be removed from the soil.

Checking the salt index of fertilisers

All fertilisers have a salt index which indicates what the fertiliser contributes to soil salinity.

If your irrigation water or soils are saline, changing to fertilisers with similar nutrients but with a lower salt index may help. For example, potassium chloride has a salt index of 114 but potassium sulphate has a lower salt index of 46.

Information on the salt index of each fertiliser should be available from your local supplier.

Desalinisation

Desalinisation for saline waters is technically possible, but its use is limited by cost (initial capital cost of the equipment, and high operation and maintenance costs) and the problem of disposing of the residual saline concentrate.

General problems to consider with desalinisation treatments:

  • Pre-treatment of the water may require sand filtration, micro-filtration, and ultraviolet treatment to kill bacteria.
  • Water with high iron, silica or manganese is difficult to treat.
  • It takes 2-3 days to properly sanitise membranes.
  • Membranes are operating under high pressure, and have a 3-year life.

Normal agricultural uses would not warrant the cost and maintenance of desalinisation. For example, for a reasonable quantity of water at 800 µS/cm salinity, a system to recover 75% of the water would have an initial capital cost of about $160,000 (1998 values), and operating and maintenance costs of about 50-60 cents per kilolitre of water treated.

At a 75% recovery rate, every megalitre of water treated would leave most of the salt in the remaining 250,000 litres: this extremely high saline concentrate would need to be disposed of in an environmentally acceptable manner.

Further reading

*Grapevine rootstocks for saline conditions are discussed in several publications including
Using Grapevine Rootstocks – The Australian Perspective by Peter May and
Viticulture – Volume 1 edited by B. Coombe and P. Day.

A web site offering information on water quality, part of the National Water Quality Management Strategy, is http://agriculture.gov.au/water/quality/nwqms

Awad, A. S. 1984, Water quality assessment for irrigation.

Australian National Committee on Irrigation & Drainage 2001, Rural Water Industry Terminology and Units, 2nd edn, ANCID/Sinclair Knight Merz, Armadale.

Handreck, K. and Black, N. 1991, Growing Media for Ornamental Plants and Turf, University of NSW Press, Kensington.

K. Horlocks, Memtec Pty Ltd.

Salt Tolerant Vegetable Gardening

Theresa Badurek, Urban Horticulture Agent, UF/IFAS Extension

Do you live in a coastal area where saline (salty) irrigation water is an issue? Some gardeners on the coast as well as some inland gardeners should be concerned about the salt levels in their well water. Water with salt levels above 1,000 parts per million will kill many plants, including beans, cucumbers, lettuce, and tomatoes. If your well is salty, it is recommended that you use fresh water from another source such as your city’s water supply to supplement irrigation. For more information on how well water may become salty, read the “Salt Water Intrusion” section of Florida’s Water Resources.

What if you are not sure if your well water is salty? Well, we can test that for you at the UF/IFAS Pinellas County Extension office at 12520 Ulmerton Rd., Largo, FL 33774. Water tests cost $10 each (cash or check only) and can be done Mon.-Fri. between 8am-5pm, excluding County holidays. Bring in about a cup of your well water in any clean container. Testing is quick and will be done while you wait. Results are given in parts per million (ppm). We can only test for dissolved salt in your water sample- no other contaminants. For any other water quality testing please consult the county health department.

Another smart gardening solution is to plant salt-tolerant vegetables. That’s right- some veggie crops can tolerate salt better than others. The jury is still out on exactly how many parts per million each plant can handle but anything over 1000ppm is too high for most. Here is a handy list from the University of Florida researchers (highest tolerance assumed to be around 1000ppm):

High Salt Tolerance

Beets, photo: Purdue

  • Beets
  • Bell peppers
  • Broccoli
  • Cabbage
  • Kale
  • Loquats
  • Spinach
  • Tomatoes

Moderate Salt Tolerance

Carrots, photo: National Junior Horticultural Association

  • Carrots
  • Cauliflower
  • Lettuce
  • Peas
  • Potatoes
  • Squash
  • Sweet Corn

Low Salt Tolerance

Cucumbers, photo: Purdue

  • Beans
  • Celery
  • Cucumbers
  • Radishes

Source: http://gardeningsolutions.ifas.ufl.edu/plants/edibles/vegetables/watering-the-vegetable-garden.html

Other things to do in April in your veggie garden: Continue planting warm season crops such as bean, cantaloupe, and okra. Mulch well to prevent weeds, and provide water if the weather has been dry.

For more vegetable gardening info see the UF/IFAS fact sheet Florida Vegetable Gardening Guide.

by tbadurek

Posted: March 28, 2014

Category: Fruits & Vegetables, Home Landscapes

Tags: coastal gardening, gardening, salt tolerant plants, vegetable garden, vegetable gardening, vegetables

Salinity Management Guide

Part of a broader process

Selecting salt-tolerant species of plants for a particular landscape is somewhat more complicated than it might at first seem. In many cases, you cannot simply pick the requisite number of plants from a list of salt-tolerant species. Instead, you’ll need to choose species based on multiple criteria.

Selecting plants according to these criteria should be viewed as one element of a comprehensive, multi-step design process. The main plant-related steps in that process are shown in Figure 1.

The first step is to determine the needs of the site’s potential users and of the site itself — drainage improvements, soil improvements, and so forth. Use the information acquired from surveying the users and studying the site for Step 2: preparing a list of criteria for selecting plants.

The criteria can be categorized as either aesthetic, or biological, or functional. The following tables provide some examples.

Some typical aesthetic criteria

  • Size of plant
  • Form and texture of plant
  • Color of foliage
  • Deciduous versus evergreen
  • Predictability of growth characteristics and form
  • Seasonality, size, texture, and color of any flowers
  • Attractiveness to birds or butterflies

Typical biological criteria for selecting plant species

  • How well-suited is the species to the local climate?
  • How tolerant is the species to salt in the soil…
  • …Or to deposition of salt on its leaves?
  • Can the species tolerate low levels of oxygen in soil (often a result of excess water)?
  • Tolerant of atmospheric pollution?
  • Tolerant of low soil moisture? (drought tolerance)
  • How susceptible is the species to diseases and pests?

Some typical functional criteria

  • For shade trees, little or no fruit (nor dropping of fruit) is a requirement
  • For all trees, having minimal leaf litter usually is desirable
  • Lack of objectionable odor is another requirement
  • Is it likely the plant’s roots will disrupt paving?
  • Is the plant likely to suffer damage from wind?
  • Non-poisonous, non-allergenic

With the list of criteria in hand, you begin Step 3: creating a conceptual design of your site’s planting areas according to aesthetic criteria. Once that conceptual design has been reviewed and approved, there’s a fourth step: refining the design according to biological and functional criteria. Eventually, you arrive at a final design and a list of species.

One or more of the computer-based programs for selecting plants that have become widely available recently may be helpful in creating an initial list of potential species for your landscape. These programs on CD-ROMs query the user about specific criteria and then search their databases for appropriate plants. One such program is Interactive Guide to Your Yard and Garden, produced by Sunset New Media. Another is Southern Trees, which covers 887 trees and shrubs grown in the United States.

At the core of this process is a careful consideration of the numerous factors related to plants and their interactions with the environment, salt tolerance among them. Adopting such a comprehensive approach helps to ensure that plants are well matched to the landscape’s soil and to the local and regional climate. Focusing solely on salt tolerance without considering climate and other factors may lead to the selection of plants that need extra care, if not eventual replacement.

Water salinity and plant irrigation

Introduction

Salts in irrigation water are mainly common salt (sodium chloride), calcium and magnesium bicarbonates, chlorides and sulphates. In most areas of Western Australia, about three-quarters of the total soluble salt is sodium chloride, though this may vary in coastal and pastoral areas. For example, in irrigation water at Carnarvon, only about half the total soluble salt is sodium chloride.

Crop yields can be markedly reduced before visual symptoms of salinity damage become apparent.

The first of sign of salinity is usually stunted growth, with plant leaves often having a bluish-green colour. As salt levels in the soil increase to more toxic levels, scalding or burning on the tip and edges of the older leaves occurs. The leaf dies and falls off and finally, the plant dies. In other cases, the youngest leaves may appear yellow, or the crop may show signs of wilting, even though the soil appears adequately moist.

Salty irrigation water can affect plant growth in two ways: salinity effect and toxicity effect.

Salinity effect

Plant roots take up moisture through membranes in root cells by osmosis. Water passes through a semi-permeable membrane, and moves from a solution of low levels of dissolved salts to one with higher salts.

This process continues until the plant cells become full. If the irrigation water is moderately saline, the plant has to work harder to absorb water from the soil and growth is slowed, with reduced yields.

If highly saline irrigation water is used, the process of osmosis can reverse. Where the solution outside the plant roots is higher in salt concentration than that of the root cells, water will move from the roots into the surrounding solution. The plant loses moisture and suffers stress. This is why symptoms of high salt damage are similar to those of high moisture stress.

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Toxicity effect

Excessive concentrations of sodium and chloride ions in irrigation water can cause toxicities in plants. These ions can be taken up either by the roots or by direct contact on the leaves. More damage is caused by direct absorption through the leaves.

Sodium

Typical sodium toxicity symptoms are leaf burn, scorch and dead tissue along the outside edges of leaves. In contrast, the symptoms of chloride toxicity occur initially at the extreme leaf tip. High concentrations of sodium in irrigation water can induce calcium and potassium deficiency in soils low in these nutrients, and crops may respond to fertilisation with these nutrients. Another effect of sodium is that if sodium is high in relation to calcium and magnesium, waterlogging may result due to the degradation of well-structured soils.

The direct toxic effects of sodium concentrations in irrigation water on different plants are shown in Table 1, which lists the effect of the sodium absorption ratio (SAR) of the irrigation water. The SAR measures the relative percentage of sodium ions in water to calcium and magnesium ions. A high SAR indicates there is potential for sodium to accumulate in the soil. This can degrade soil structure by breaking down clay aggregates, which results in waterlogging and poor plant growth.

Table 1 Tolerance of crops to sodium

Tolerance Sodium adsorption ratio of irrigation water Crops
Very sensitive 2–8 Avocado, citrus, deciduous fruits and nuts
Sensitive 8–18 Beans
Moderately tolerant 18–46 Clover, oats, tall fescue, rice
Tolerant 46–102 Barley, beets, lucerne, tomatoes, wheat

Chloride

The chloride ion can be taken up by plant roots and accumulate in the leaves. Excessive accumulation may cause burning of the leaf tips or margins, bronzing and premature yellowing of the leaves. In general, most fruit trees are sensitive to chloride, whereas most vegetable, forage and fibre crops are less sensitive. Table 2 shows the tolerance of some crops to chloride damage by root uptake.

Crops, and even varieties and rootstocks, vary greatly in their tolerances to chloride and sodium. If irrigation water has a total salinity close to the critical concentration, then test its chloride and sodium concentrations.

Chemical analysis of soil or leaves can be used to confirm probable chloride toxicity. Fruit leaves usually suffer from toxicity when the dried leaves contain more than 0.2% sodium or 0.5% chloride.

Table 2 Chloride upper tolerance limits for some fruit crops, cultivars and rootstocks by root uptake

Crop (variety/rootstock) Chloride concentration in irrigation water
(mg/L)
Citrus rootstocks
trifoliata 120
rough lemon 200
troyer citrange, sweet orange 300
Rangpur lime, Cleopatra mandarin 600
Stone fruit rootstocks
Marianna plum (for budding plums and apricots) 600
Myrobolan plum (for budding plums and apricots) 370
Peach 235
Avocado rootstocks
Mexican 120
West Indian 190
Grape rootstocks
Ramsey 950
Dog Ridge 700
Sultana 600
Soft fruit varieties
Blackberry, boysenberry 235
Raspberry 120
Strawberry 120–190

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Direct adsorption through leaves

Some crops which are not sensitive to root uptake of chloride or sodium ions develop symptoms of leaf burn when sprinkled with saline water.

Damage is most severe during hot dry conditions because evaporation concentrates the salts on leaf surfaces. Table 3 shows chloride and sodium concentrations in irrigation water that will damage the leaves of certain crops.

Table 3 Chloride and sodium concentrations in irrigation water causing damage to leaves

Sensitivity Chloride (mg/L) Sodium (mg/L) Affected crop
Sensitive

<178

<114

Almond, apricot, citrus, plum
Moderately sensitive 178–355 114–229 Capsicum, grape, potato, tomato
Moderately tolerant 355–710 229–458 Barley, cucumber, sweetcorn
Tolerant

>710

>458

Cauliflower, cotton, safflower, sesame, sorghum, sunflower

Leaf injury is influenced by cultural and environmental conditions such as drying winds, low humidity, speed of rotation of sprinklers and timing and frequency of irrigations. Data presented are only general guidelines for summer daytime sprinkling.

Measuring salinity

Salinity of water is usually estimated from its electrical conductivity (EC), which may be converted to total dissolved solids (TDS). The EC does not identify the dissolved salts, or the effects they have on crops and soil, but gives a fairly reliable indication of salinity problems. Table 4 shows a general salinity classification for water.

EC is measured in milliSiemens per metre (mS/m) in DPIRD. Some laboratories use different units for salinity.

To convert EC to milligrams per litre (mg/L) or parts per million (ppm) of TDS, multiply a measurement in mS/m by 5.7, or a measurement in mS/cm or dS/m or mS/cm by 570. These conversion figures are approximate, suitable for EC readings of less than 1000mS/m and for the common salts found in WA irrigation water.

Table 4 General salinity classification for water

EC
(mS/cm, dS/m or mmhos/cm)
EC
(mS/m)
Approximate total dissolved solids
(mg/L or ppm)
Status
0–0.80 0–80 0–456 Low salinity
0.80–2.50 80–250 456–1425 Moderately salty
2.50–5.00 250–500 1425–2850 Salty

>5.00

>500

>2850

Very salty

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Factors affecting damage

The extent of plant yield loss when irrigated with saline water depends on a number of factors including:

Soil type and drainage

The key to irrigating successfully with saline water is to leach or move salts downwards away from the root zone.

In well drained sandy soils, irrigation water can readily flush salts out of the root zone but this is less successful on poorly drained, heavy soils. The amount of leaching to maintain acceptable growth depends on:

  • salinity of the irrigation water
  • salt tolerance of the crop
  • climatic conditions
  • soil type
  • water management.

The amount of additional water required to leach salt from the root zone is called the leaching fraction.

Frequency and timing

Salt concentration in the root zone continually changes following irrigation. As the soil dries, the salt concentration in the soil solution increases and this reduces the moisture available to the plant. Frequent, light irrigations increase salt concentrations in the topsoil and should be avoided.

High rainfall and heavy irrigations will remove salts from within the root zone.

Watering during hot dry conditions will increase evaporation and therefore increase the concentration of salt.

Fertilising

If salinity is a problem, avoid fertilisers containing chloride.

Replace muriate of potash (potassium chloride) with sulphate of potash and use nitrogen, phosphorus and potassium (NPK) fertilisers which contain sulphate of potash.

Growth stage

Plants are generally more susceptible to salinity damage during germination and at the seedling stage than when established.

The best quality water should be used at this stage.

Rootstocks and varieties

Rootstock and variety differences are important factors affecting salt tolerances of tree and vine crops, especially with avocado, citrus, grapes and stone fruit (see Table 2).

Irrigation method

Drip irrigation allows water with higher salt content to be used than other delivery methods, as evaporation losses are minimal.

Drip irrigation can alsoreduce the effects of salinity by maintaining continuously moist soil around plant roots and providing steady leaching of salt to the edge of the wetted zone.

Sprinkler irrigated crops are potentially subject to additional damage caused by salt uptake into the leaves and burn from spray contact with the leaves.

If using saline water for sprinkler irrigation, irrigate when temperatures are coolest. Watering in the heat of the day concentrates the salts due to high evaporation. Watering during high winds also concentrates salts.

Do not use sprinklers which produce fine droplets and misting. Avoid knocker sprinklers if possible, especially slow revolution sprinklers which allow drying periods, causing salt to build up on the leaves.

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Guidelines for critical salinity

Tables 5 to 8 show the tolerance of plants to irrigation with saline water. These values should only be used as a guide because the extent of salinity damage depends on the factors described previously.

If the salinity of the water is near the upper recommended limit, conduct preliminary trials under the specific conditions present to determine if crop damage will occur.

Tables 5 to 8 also show the threshold salinity at which yield begins to decline (0% yield loss) and the salinity at which 10% and 25% of yield is lost. Changes of water salinity of 20% above or below the indicated salt tolerance value may have little effect because of the modifying effect of soil, climate and management. The yield loss data depends on several assumptions.

The crop tolerance figures relate to a loamy soil, with good drainage and with at least 15% of the applied water percolating below the root zone (leaching fraction 15% or more). These figures are applicable to sprinkler irrigation systems in which there is an extended drying period between irrigations. Crops can usually tolerate higher salinity under higher frequency irrigation.

These guidelines are likely to be too restrictive for sprinkler irrigation on very permeable sands of the Swan Coastal Plain. Irrigation on these soils is frequent, often with a leaching fraction over 15%. Sprinkler irrigation of crops with water high in chlorine or sodium may result in damage via absorption through the leaves, even though the salinity concentration is below the critical level listed in Tables 5 to 8.

The guidelines apply mainly to sprinkler irrigation. Trickle irrigation is applied frequently which reduces salinity concentrations in the root zone and increases in salinity due to evaporation are minimal.

For crops where yield loss data is not available, a maximum recommended concentration or range of concentrations is given.

Recycling of salts

Groundwater below horticultural properties on the Swan Coastal Plain may become more saline over time. The longer an area is irrigated, the higher the risk. Large amounts of water are pumped from the shallow aquifer in some areas. As excess irrigation water infiltrates back to the aquifer, the salt level increases because of evaporation and addition of fertiliser salts. Good irrigation management should, in most cases, overcome these problems. Excessive pumping from an aquifer can also result in the intrusion of salty water.

If several sources of differing quality water are available, blend the poorer quality with better quality to reduce or prevent salinity damage.

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Analysis of water samples

A number of laboratories in Western Australia will analyse water for electrical conductivity. Check the Yellow Pages phone book for contact details.

Use a glass or plastic bottle that is about 500mL capacity. Rinse the bottle in the water to be sampled before filling. Seal the bottle and mark it with the sender’s name and address, and date of sampling.

When sampling from bores or wells, run the pump for a few minutes to ensure a representative sample is taken. Large variations in the salinity of surface irrigation water can occur throughout the year, usually highest from the end of summer until the first rains. Collect the water sample at the time of year when water will be pumped for use.

Crop tolerance tables

Table 5 Vegetable crop tolerance to irrigation with saline water on loamy soil

Crop

0% yield loss

EC (mS/m)

10% yield loss

EC (mS/m)

25% yield loss

EC (mS/m)

Asparagus 270–635 No data available No data available
Bean 70 100 150
Beetroot 270 340 450
Broccoli 190 260 370
Cabbage 120 190 290
Capsicum 100 150 220
Carrot 70 110 190
Cauliflower 90–270 No data available

No data available

Celery 120 230 390
Cucumber 170 220 290
Kale 270-635

No data available

No data available

Lettuce 90 140 210
Onion 80 120 180
Parsnip 90 No data available No data available
Peas 90 No data available No data available
Potato 110 170 250
Pumpkin 90–270

No data available

No data available

Radish 80 130 210
Rockmelon 90–270 No data available No data available
Spinach 130 220 350
Squash 210 260 320
Sweetcorn 110 170 250
Sweet potato 100 160 250
Tomato 170 230 340
Watermelon 150 240 380

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Table 6 Fruit crop tolerance to irrigation with saline water with loamy soil

Crop

0% yield loss

EC (mS/m)

10% yield loss

EC (mS/m)

25% yield loss

EC (mS/m)

Almond 100 140 190
Apple No data available 150 No data available
Apricot 110 130 180
Avocado 90 No data available

No data available

Blackberries 100 130 180
Date palm 270 450 730
Fig No data available 253 No data available
Grapefruit 120 160 220
Grape 100 170 270
Mulberry 90–270 No data available No data available
Nectarine 90

No data available

No data available
Olive No data available 250 No data available
Orange 110 160 220
Peach 110 130 180
Pear No data available 150 No data available
Plum 100 140 190
Pomegranate No data available 250 No data available
Raspberry No data available 90 No data available
Strawberry 70 90 120

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Table 7 Pasture and fodder crop tolerance to irrigation with saline water with loamy soil

Crop

0% yield loss

EC (mS/m)

10% yield loss

EC (mS/m)

25% yield loss

EC (mS/m)

Birdsfoot trefoil 330 400 500
Cocksfoot 100 210 370
Couch 270–635 No data available No data available
Kikuyu grass 270–635 No data available No data available
Lovegrass 130 210 330
Paspalum dilatatum 270–635 No data available No data available
Perennial ryegrass 370 460 590
Phalaris 310 380 530
Puccinellia 635–2365 No data available No data available
Red clover 100 160 240
Rhodes grass 270–635 No data available No data available
Saltwater couch 635–2365 No data available No data available
Strawberry clover 100 160 240
Sub clover 100 110 240
Sudan grass 190 340 570
Tall fescue 260 390 570
Tall wheat grass 500 660 900
White clover 90 No data available No data available
Barley (hay) 400 490 630
Lucerne 130 220 360
Maize 110 170 250
Sorghum 450 500 560

In Tables 5, 6 and 7 detailed yield loss data is not available for some crops. A maximum recommended concentration or range of concentrations is given. The data should serve only as a guide. Absolute tolerances vary depending on climate, soil conditions and cultural practices.

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Table 8 Maximum recommended electrical conductivity of irrigation water for selected ornamentals with increasing tolerance within groups

EC (mS/m) Plant
90 Primula, gardenia, star jasmine, begonia, rose, azalea, camellia, ivy, magnolia, fuchsia
90–270 Hibiscus, geranium, gladiolus, bauhinia, zinnia, aster, poinsettia, lantana, Thuja orientalis, hop bush (Dodonea attenuata), banana emu bush (Podocarpus), Juniperus chinensis, bottlebrush
270–635 Stock, chrysanthemum, carnation, oleander, rosemary, bougainvillea, vinca, coprosma, Ficus spp., NZ Christmas bush (Metrosideros excelsa), Bangalay gum (Eucalyptus botryoides), river red gum (E. camaldulensis), Rottnest teatree (Melaleuca lanceolata), Rottnest cypress (Callitris preissii), Acacia longifolia, buffalo grass, kikuyu, portulaca, boobialla (Myoporum acuminatum), morrel (E. longicornis), swamp yate (E. occidentalis), York gum (E. loxophleba), swamp mallet (E. spathulata), couch grass, bamboo
635–2365 Salt river gum (E. sargentii), saltwater couch, Melaleuca thyoides, salt sheoaks (Allocasuarina cristata and A glauca), saltbush

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