CMG GardenNotes #224 Saline Soils

Transcription

1 CMG GardenNtes #224 Saline Sils Outline: Sluble Salts, page 1 Impact f high salt n plant grwth, page 1 Factrs cntributing t salt prblems, page 2 Drainage, page 2 Sil amendments, page 2 Excessive r unnecessary fertilizatin, page 2 De-icing salts, page 3 Pet urine, page 3 Measuring sil salt levels, page 3 Managing sil salts, page 4 Leaching salts, page 4 Adding sil amendments, page 4 Other management techniques, page 5 Sluble Salts The term sluble salts refers t the salts (ins) disslved in the sil s water. Sme salts such as gypsum (calcium sulfate) are less sluble. Limestne (calcium carbnate) disslves nly in acidic water. Others like sdium chlride (table salt0 disslves very easily and bnds with water mlecules making it hard fr plants t absrb the water. Salts are anther sil factr limiting crp grwth in sme areas f Clrad, especially in the Western Clrad Valleys. The salty layer f the Grand Valley is Mancs shale that can have a depth up t Sme salts such as Brn, chlride and sdium can be txic t plants. Impact f High Salt n Plant Grwth High salt levels can reduce water uptake by plants, restrict rt grwth, cause marginal burning f the fliage, inhibit flwering, limit seed germinatin, and reduce fruit and vegetable yields. Irregular bare spts in gardens and uneven crp grwth suggest salinity prblems. Crp yields may be reduced as much as 25% withut any damage being apparent. Salt injury generally is mre severe during perids f ht dry weather, when water use is high. Sensitivity t sluble salts differs amng plant species/cultivars and is dependent n their state f grwth. Seed germinatin and seedling grwth are mre sensitive t salt stress than mature plants. [Table 1] Salt burn n bean leaf frm high salts in cmpst

2 Table 1. Relative Salt Tlerance f Cultivated Plants Nn-tlerant 0-2 ds/m Slightly 2-4 ds/m Mderately 4-8 ds/m 8-16 ds/m begnia apple beet arbrvitae carrt cabbage black lcust asparagus ctneaster celery bxwd juniper green bean cucumber brccli Russian live nin grape chrysanthemum Swiss chard pea frsythia creeping bentgrass radish Kentucky bluegrass geranium raspberry lettuce marigld red pine linden muskmeln rse Nrway maple perennial ryegrass strawberry pepper red ak sugar maple ptat spinach viburnum red fescue squash white pine red maple tmat snapdragn sweet crn white ash white ak zinnia Nte: ds/m is the unit used t measure salt cntent. It measures the electrical cnductivity f the sil. ds/m = mmhs/cm Factrs Cntributing t Salt Prblems Drainage A cmmn sign f salt prblems is the accumulatin f salts at the sil surface due t limited perclatin in cmpacted and/r clayey sils. Sluble salts mve with the sil water. Deep perclatin f water dwn thrugh the sil prfile mves salt ut f the rting zne. Surface evapratin cncentrates the salts at the sil surface. Salt depsits may r may nt be seen as a white crust n the sil surface. As yu drive arund Clrad, it is cmmn t see these sils with the white salt accumulatin in lw spts f fields and natural areas. In sme areas, salt naturally accumulates due t limited rainfall t leach the salt ut. Salt levels drp when the sil underges irrigatin. In ther areas, salts may build-up when pr sil drainage prevents precipitatin and irrigatin water frm leaching the salt dwn thrugh the sil prfile. In this case, crrective measures are limited t imprvements in sil drainage. Sil Amendments Manure, bislids, and cmpst made with manure r bislids may be high in salt. When using manure r cmpst made with manure, rutinely mnitr salt levels. Fr mre infrmatin, see the sectin n Sil Amendments

3 Excessive/Unnecessary Fertilizer Applicatins Unwarranted applicatin f fertilizers (such as phsphate r ptash) increases the salt level. On sils marginally high in salts, ptash fertilizers shuld be avided unless a ptassium deficiency is identified by sil tests. Over- fertilizatin als has ther envirnmental impacts. Placing fertilizer and salty sil amendments t clse t seeds r plant rts creates a salt burn f the tender rts. Germinatin failure r seedling injury can result. De-Icing Salts The use f de-icing salts n streets and sidewalks frequently results in high salt levels in adjacent sils. Alng rads, salt injury has becme a majr cncern. Highway salts may reach plants in tw ways: mvement t sil and uptake by plant rts, r mvement nt plant stems and fliage thrugh the air as vehicle splash-back. Salts depsited n bth sil and fliage have high ptential t cause plant injury. Highway salts in rad-melt runff is anther cncern fr plants and the wider envirnment. Pet Urine Damage by pet urine is als a salt prblem cntaining alkaline salts and nitrgen. Water mves by smtic pressure frm the rts t the high salt cncentratin in the sil, dehydrating and killing rts. Train yur pet t eliminate in a plant free zne r fllw ther salt management methds belw. Measuring Sil Salt Levels Bean plants are rather salt sensitive and can be used t help assess salt prblems. In a garden, if beans are ding well, sluble salts are nt a prblem. If the beans are ding prly, cnsider salts as a pssibility. Beans, tmates and ther easily germinated seeds can be used in a pt test n a windwsill t live assay the salt cntent f a sil. Assess plants perfrmance in light f Table 1. The amunt f salt in a sil can be quantified nly by a sil test. A sil test fr sluble salts can be useful when investigating the cause f pr plant grwth, determining the suitability f a new planting site, r mnitring the quality f fill sil r sil amendments fr use n a landscape area. Sil tests fr sluble salts are based n electrical cnductivity. Pure water is a very pr cnductr f electric current, whereas water cntaining disslved salts cnducts current apprximately in prprtin t the amunt f salt present. Thus, measurement f the electrical cnductivity, ECe, f a sil extract gives an indicatin f the ttal sluble salt cncentratin in the sil. The ECe is measured in decisiemens per meter (ds/m) r millimhs per centimeter (mmhs/cm). 1 ds/m = 1 mmhs/cm. [Table 2] 224-3

4 Table 2. Sluble Salt Test Values and Relative Sensitivity Levels f Plants Electrical Cnductivity 1 (ds/m) Salinity Level Effect n Plant Grwth 0 t 2 nn-saline nne 2.1 t 4 very slight salinity sensitive plants are inhibited 4.1 t 8 mderately salinity many plants are inhibited 8.1 t 16 strngly salinity mst cultivated plants are inhibited ver 16 very strngly salinity few plants are tlerant 1 Saturated paste extract Managing Sil Salts Leaching Salts Leaching is the nly practical way f remving excess salts. This is effective nly t the extent that water mves dwn thrugh the sil prfile and beneath the rt zne (drainage must be gd). The amunt f salts remved depends n the quantity and quality f water leached thrugh the sil prfile during a single irrigatin perid. Water shuld be lw in salts (high quality) and must nt run ff the surface. It shuld be applied slwly s amunts d nt exceed the ability f the sil t take in water (infiltratin rate). If yu see pets urinate n a plant, rinse and flush with water within 8 hurs. The fllwing amunts f water applied in a single, cntinuus irrigatin will disslve and decrease sil salts by these fractinal amunts: 6 inches f water will leach abut ½ the salt 12 inches f water will leach abut 4/5 f the salt. 24 inches f water will leach abut 9/10 f the salt. Adding Sil Amendments Salty sils are nt reclaimable when the sil s clay cntent, cmpactin, r hardpan prevents leaching. Because manure, bislids, and cmpst made frm manure r bislids may be high in salts, d nt add mre than 1 inch per seasn withut a sil test t evaluate salt levels. An amendment with up t 10 ds/m ttal salts is acceptable if mixed thrugh the upper six t eight inches f a lw-salt sil (less than 1 ds/m). Amendments with a salt cntent greater than 10 ds/m are questinable. Avid these sil amendments in sils that are already high in salts (abve 3 ds/m) when grwing the salt sensitive plants. Nte: Because sil amendments are nt regulated in Clrad, d nt assume that prducts sld in bags r by bulk are necessarily lw in salt cntent and gd fr the garden s sil. Many cmmercially available surces f manure, bislids, and cmpst made with manure r bislids have excessively high levels f salt. Sme cmpanies d test, s ask if they have recent salt levels f the amendment

5 On marginally salty sils, cncentrate n gradually imprving the sil rganic cntent and activity f sil micrrganisms and earthwrms. D nt exceed recmmended rates per applicatin as large quantities f rganic matter can hld salts next t plant rts and cause injury. Organic amendments applied ver time imprve sil tilth, which then will imprve the ptential fr effective leaching as well as plant grwth. Other Management Techniques Plants grwn n salty sils are less tlerant f dry sil cnditins. Plants will require mre frequent irrigatin, with reduced amunts f water. Within pedestrian and vehicle safety limits, avid the use f de-icing salts. Cnsider the use f sand r ther abrasive materials fr use n slick sidewalks and pavement. Where de-icing salts are rutinely used, expect t find salt prblems in adjacent sils and drainage swales where the snwmelt runs. Because sil salt levels frm de-icing salts easily rise abve the tlerance f even the mst salttlerant plants, a rck mulch area withut plants may be a better landscape design slutin in salt use areas. Fr additinal details n sil salt issues, refer t the fllwing CSU Extensin fact sheets #7.227, Grwing Turf n Salt-Affected Sites. Authrs: David Whiting (CSU Extensin, retired), Adrian Card (CSU Extensin), Carl Wilsn (CSU Extensin, retired), and Jean Reeder, Ph.D., USDA-ARS (retired). Artwrk by David Whiting; used by permissin. Revised by Susan Carter, (CSU Extensin) Clrad Master Gardener GardenNtes are available nline at Clrad Master Gardener training is made pssible, in part, by a grant frm the Clrad Garden Shw, Inc. Clrad State University, U.S. Department f Agriculture and Clrad cunties cperating. Extensin prgrams are available t all withut discriminatin. N endrsement f prducts mentined is intended nr is criticism implied f prducts nt mentined. Cpyright Clrad State University Extensin. All Rights Reserved. CMG GardenNtes may be reprduced, withut change r additins, fr nnprfit educatinal use with attributin. Revised Octber