Two laboratory-prepared ferric hydroxy bi-selenites and
CuSeO? applied to Portneuf silt ham in the field provided
slowly available Se to alfalfa, resulting in Se concentration adequate
but nontoxic for livestock. These materials have potential
as Se fertilizers at low application rates. The ferric hydroxy
bi-selenites offer little or no advantage over CuSeO?. Se from
BaSeO? alone, BaSeO?—BaSO? mixtures, and CuSeO? was
absorbed by alfalfa in concentrations toxic to livestock. A small
fraction of applied elemental Se was available immediately
after application, providing adequate Se to alfalfa for livestock.
The remaining elemental Se was rather inert, and supplies only
slightly more Se to alfalfa than did the untreated soil the year
following application

Brown, M.J.

Carter, D.L.

Robbins, C.W.

Two laboratory-prepared ferric hydroxy bi-selenites and
CuSeO₃ applied to Portneuf silt ham in the field provided
slowly available Se to alfalfa, resulting in Se concentration adequate
but nontoxic for livestock. These materials have potential
as Se fertilizers at low application rates. The ferric hydroxy
bi-selenites offer little or no advantage over CuSeO₃. Se from
BaSeO₄ alone, BaSeO₄—BaSO₄ mixtures, and CuSeO₄ was
absorbed by alfalfa in concentrations toxic to livestock. A small
fraction of applied elemental Se was available immediately
after application, providing adequate Se to alfalfa for livestock.
The remaining elemental Se was rather inert, and supplies only
slightly more Se to alfalfa than did the untreated soil the year
following application

USDA - ARS - NWISRL

Reprinted from the Soil Science Society of America ProceedingsVolume 33, Number 5, September-October 1969677 South Segoe Road, Madison, Wisconsin 53711 USAPurchaaed by the Agricultural Research Service, U. S. Department of Agriculture, for official use.Selenium Concentrations in Alfalfa From Several SourcesApplied to a Low Selenium, Alkaline Soil 1D. L. CARTER, M. J. BROWN, AND C. W. ROBBINS 2ABSTRACTTwo laboratory-prepared ferric hydroxy bi-selenites andCuSeOs applied to Portneuf silt ham in the field providedslowly available Se to alfalfa, resulting in Se concentration ade-quate but nontoxic for livestock. These materials have poten-tial as Se fertilizers at low application rates. The ferric hydroxybi-selenites offer little or no advantage over CuSe0s. Se fromBaSe04 alone, BaSeO4—BaSO4 mixtures, and CuSe04 wasabsorbed by alfalfa in concentrations toxic to livestock A smallfraction of applied elemental Se was available immediatelyafter application, providing adequate Se to alfalfa for livestock.The remaining elemental Se was rather inert, and supplies onlyslightly more Se to alfalfa than did the untreated soil the yearfollowing application.Additional Key Words for indexing: white muscle disease,ferric hydroxy bi-selenites, copper selenite, selenites, copperselenate, selenates.MHE DISCOVERY that Se is required for normal animalI nutrition stimulated considerable related research. Gen-eral and detailed maps of the Se content of forage and haycrops grown in the USA have been published (4, 12) aswell as maps relating the occurrence of white muscle dis-ease (WMD), a Se-responsive myopathy (14) , to areasknown to produce low Se forage (12, 15). The minimalSe concentration required in the animal diet ranges be-tween 0.03 and 0.10 ppm depending upon the vitaminE level in the diet and other factors (1). Many consider0.10 ppm Se as a safe minimum. Se concentrations above3 to 4 ppm are toxic (17), and small applications of Se1 Contribution from the Northwest Branch, Soil and WaterConservation Research Division, ARS, USDA, Idaho Agr. Exp.Sta. cooperating. Received Feb. 10, 1969. Approved June 17,1969.2 Research Soil Scientist and Soil Scientists, respectively,Snake River Conservation Research Center, Kimberly, Idaho83341.have repeatedly produced plant concentrations of Se toxicto livestock (3, 8, 9, 12, 15). Where total Se concentra-tions in the soil in the Central United States range from2 to 13 ppm, Se toxicity problems have occurred repeatedly(13).Current regulations do not permit the direct addition ofSe to animal feeds. Stockmen frequently use Se injectionsto prevent WMD in lambs and calves. Se compounds assoil additives can be used to provide plants with protectivebut nontoxic Se concentrations. The application of Na 2SeOsto acid and neutral soils has successfully prevented WMDin animals consuming the forage produced. However,application rates must be carefully controlled to avoidplant concentrations toxic to livestock (3, 7). Se treatmentof alkaline soils may be especially difficult, because Secompounds may oxidize to form soluble selenates in analkaline environment (6, /2). Se concentrations toxicto animals were found in 20 plant species grown in thegreenhouse on alkaline soils receiving 5 to 20 ppm Se asNa2Se0s, Na2Se04 or organic Se in the form of groundplant material (9). Alfalfa (Medicago sativa L.) grownin the greenhouse absorbed Se in concentrations toxic tolivestock from four of seven soils treated with Se at a2.5-ppm rate as selenized concentrated superphosphate(6). Se concentrations toxic to animals were found inalfalfa grown in the greenhouse on Madras sandy loam soil,an acid soil, when Na2Se03 treatment rates exceeded 1.0ppm Se. Alfalfa grown in the field on the same soil treatedwith 1.12 kg Se/ ha contained up to 2.7 ppm Se (3), aconcentration range safe for livestock. Topdressing withabout 0.07 kg Se/ha as Na2Se0, or Na2Se04 on NewZealand pasture resulted in Se concentrations toxic to live-stock for periods of more than a year after application (8).In this case plant crowns apparently absorbed Se, anduptake was greater than if the Se had been applied onlyto the soil.The uptake of Se from soils appears to be dependent716	SOIL SCI. SOC. AMER. PROC., VOL. 33, 1969upon the pH of the soil. Thus, there is a need for evaluatingSe compounds as soil additives to provide slow and longlasting Se availability to plants grown on alkaline soils.This paper reports results of a field study conducted toevaluate the Se availability to alfalfa (Medicago sativa L.%anger') as influenced by the application of commerciallyavailable and laboratory prepared (ferric hydroxy bi-sele-nites) Se compounds to an alkaline Portneuf silt loam.Several types of additives containing Se compounds wereincluded as suggested in the literature. BaSO 4 was addedwith Se compounds as suggested by an observation that(i) CaSO4 or BaCl2 applications to an alkaline soil greatlyreduced Se uptake (16), and (ii) by evidence that S andSe compounds compete in plant uptake and assimilation(10, 11).MATERIALS AND METHODSForty-eight field plots each 2 by 5 m were established ina 1-year old stand of alfalfa growing on an alkaline Portneufsilt loam near Kimberly, Idaho. Three replications of 16 treat-ments were arranged in a randomized block design. The Se-containing materials were applied July 6, 1966 after the firstalfalfa cutting had been removed from the field. All materialswere applied using a hand-pulled shank with a tube down therear of the shank through which the constantly agitated aque-ous suspensions of the materials were dispensed. Placementwas approximately 12 cm below the soil surface in bandsapproximately 15 cm apart.The commercially available materials used and the appli-cation rates are shown in Table 1. The S/Se ratio was variedto determine the effect of Son Se uptake. In addition to thelisted materials, two laboratory-prepared ferric hydroxy bi-selenites were applied. These materials were prepared to besimilar to slightly soluble ferric hydroxy bi-selenites thoughtto be present in many acid soils (7).One of these materials was prepared by adding NH4OH toa solution of FeCI3 until excess (OH)- was present. 112Se03was then added until a slight excess was present, as detectedby the drop in pH. The precipitate was allowed to age for 48hours. It was then separated by centrifuging and washingthree times with water at an approximate water:so/id ratio of25:1. It was then dried and ground to a coarse powder. Thismaterial contained 30% Se with a Fe:Se molar ratio of 1:1,and will be referred to as (Fe) 5(OH) y (HSe03 ) 5. It wasapplied at 4 kg material/ha, equivalent to 1.2 kg Se/laa.The second ferric hydroxy bi-selenite was prepared byadding an excess of H2SeO3 to a FeC18 solution and then add-ing NI-1.40H until excess (OH)- was present. The materialwas then handled as described above. The resuiting compoundwas 54% Se with a Fe:Se molar ratio of 1:2.75, and will bereferred to as (Fe).(OH) b (HSe03),. It was applied at 4 kgmaterial/ha, equivalent to 1.62 kg Se/ha.The Portneuf silt loam used in this study is alkaline with apH of 7.8 and a cation exchange capacity of 24 meq/100 gin the surface 15 cm. Below 15 cm, free CaCO 3 is present andthe pH is 8.2. The CaC08 equivalent ranges from 17 to 25%below 25 cm. The surface layer particle size distribution is25, 54 and 21% sand, silt, and clay, respectively.Table 1-Commercially available Se containing materialsapplied to alkaline Portneuf silt loamSe applied, kg/haCarrier	 S/Se	 0.5	 0.1	 2.0	 4.1stsao,	 XB40004 and BaSD,	 1	 S	 XBaSe04 and BaSO,	 10	XCuSe0iCu.8003Element SeAlfalfa samples were collected just before harvest duringthe 1966 and 1967 seasons. Samples were composed of theupper 30 cm of growth from 10 or more plants for each plot.In 1966 the second and third cuttings were sampled July 21and September 14, respectively. The respective sampling datesin 1967 were June 21, August 8, and September 28 for thefirst, second and third cuttings. Samples from each plot weredried at 50C, ground to pass a 1-mm sieve, and analyzed forSe content by a fluorometric method (2).RESULTS AND DISCUSSIONAlfalfa readily absorbed Se from BaSeO 4 applied toPortneuf silt loam. Se concentrations toxic to livestockwere found in samples from all application rates in at leastone of the five cuttings harvested over two seasons (Table2). Evidently Se from BaSeO 4 on alkaline soil is as avail-able for plant absorption as it is from Na 2SeO4 appliedto acid and alkaline soils (8, 9). Thus, use of BaSe04would require the same precautions necessary when usingsoluble selenates to avoid plant concentrations of Se toxicto livestock.Applying BaSO 4 with BaSeO4 at a S/Se ratio of I hadno effect on the Se concentration in alfalfa. Mean Se con-centrations for the five cuttings on the 0.5, 1.0, and 2.0kg/lia application rates were 1.49, 3.09 and 7.38 ppm,respectively, where only BaSeO 4 was applied, and 1.78,3.51, and 5.27 ppm where BaSO4 was added with BaSeO4to give a S/Se ratio of 1 (also see Table 2). When theS/Se ratio was increased to 10, Se concentrations wereenhanced, particularly at the higher application rates(Table 2). This enhancement tended to disappear withtime, especially at the low application rates. Reactions inthe soil and leaching of selenate from the application zonesand possibly beyond the root zone probably account forthe decrease in effects with time. A crop response to theapplied sulfate is not a likely explanation because no cropresponses to S have been observed in the area of the study.The irrigation water supplies about three times the amountof S required by alfalfa each year. Yields were not mea-sured because yield responses were not expected in thisstudy.The results of this study contrast somewhat with reportsthat applications of BaC1 2, CaSO4 , and S decreased Seavailability to plants (10, 11, 16). These reports generallydealt with seleniferous soils or with soils treated with SeTable 2-Se concentrations in alfalfa resulting from applica-tions of BaSeO4, CuSeal, and BaSeO4-BaSO4mixtures to Portneuf silt loamSeapplicationrate carrier 6/Se1960 1987Cu Wag Cutting2nd 3rd Oat 2nd 3rdkg/ha Se concentradm,--- ppm* .--0.0 Check 0.12 0.11 0.12 0.13 0.110.2 EaSeCii 0,98 0.74 3.47 1.50 0.701.0 DaSeq. 4.26 0.79 8.83 2.69 0, 812.0 R6Se°, 6.05 2.51 19.27 6.87 3.224.0 BeSeQ 12.68 6.87 24,92 13.27 4.531.0 CitSe% 27.85 9.81 3.80 3.20 1.680.5 BaSec% + 88.80, 1 1.97 1.04 2.98 2.15 0.771.0 BaROI + BaSO, 1 4.14 1.85 7.34 3.00 1.412.0 BeSe0, + BaSO, 1 5.97 3,07 10.40 4,40 2.580,5 88.800, + BaSO, 10 5.03 1.54 5.94 1.79 0. BO1.0 BaSe04 + BaSO, 10 8.78 1.00 3.64 1,77 0.702.0 EseeCh + also. 10 33.80 11.93 11.55 5.65 2,45+ Values are means of three replications. The coefficient of variation of the meanranged from 4 to 52%, but were generally /aim than 30%.q (Fo)xliCkti)y CHS•034o (F0,3 10e0b OlSoOslca Control2nd	 3rd	1st	 2nd	 3rd1966	1967Alfalfa CuttingO Elemental Se, 4.0 Kg/haq Elemental Se. 2.0 Kg/hao CaSe0 3 1.0 Kg/ha• ControlECvCto01.5-l.0-0.5-CARTER ET AL.: SELENIUM CONCENTRATIONS IN ALFALFA	7172nd	 3rd	 1st	 2nd	3rd19 66	 1967Alfalfa	 CuttingFig. 1—Se concentration in alfalfa from CuSeOs and elementalSe applied to alkaline Portneuf silt loam. Points representmeans of three replications. Standard error of the mean forsuccessive cuttings are 0.168, 0.044, 0.088, 0.232 and 0.120,respectively, including data from both Fig. 1 and 2.compounds from which plants absorbed relatively largeamounts of Se. Our study was with a low Se, alkaline soil,and small applications of Se.Se uptake from CuSeO4 was initially very high anddecreased in each successive crop (Table 2). All cropscontained concentrations toxic to livestock except the thirdcutting in 1967. Thus, CuSeO4 should not be used as aslowly available Se source for plants.Selenites may be more useful than selenates as slowlyavailable Se additives on alkaline soils. Se uptake fromCuSe0, was in the protective and nontoxic range for live-stock in all five crops (Fig. 1). Evidently CuSe0 3 providedonly slow Se availability to alfalfa. The supply rate wasnot rapid enough to maintain the same Se concentrationsin third cuttings as in second cuttings both years. Thelonger period of time between seasons was sufficient formore Se to become available to alfalfa, resulting in greateruptake the second year than the first (Fig. 1). CuSeOsdoes have potential as a slowly available Se source, butapplication rates should not exceed 1.0 kg Se/ha.Maintenance of protective but nontoxic concentrationsof Se in alfalfa grown in the greenhouse on some acid andneutral soils treated with NaHSeOs at rates of 1 ppm Sehas been reported (5). Therefore, it may be that CuSeO3and NaHSeO5 react in about the same way in the soil, eventhough CuSeO 5 is less soluble. Other selenites may behavesimilarly in the soil.Elemental Se applied at 2.0 and 4.0 kg/ ha provided ade-quate Se in alfalfa for livestock. Small amounts of the ele-mental Se became available rapidly after application tothe soil, but later the availability decreased (Fig. 1). Bythe third cutting 1967, elemental Se at both rates suppliedonly slightly more Se to alfalfa than did the untreated soil.The low recovery of added elemental Se may render thisform of Se impractical because of cost. It might be usedat low rates of about 1/4 or 1/2 kg/ha to provide Se for oneor two crops. The elemental form is less hazardous tohandle because it is rather inert and much less toxic toman than soluble forms.The two ferric hydroxy bi-selenites provided slowlyavailable Se to alfalfa, and resulting plant concentrationsE 3.00.Fig. 2—Se concentration in alfalfa from two laboratory pre-pared-ferric hydroxy bi-selenites applied to alkaline Portneufsilt loam. (Fe) 0 ( OH ) 9 (HSe03 )0 applied at 1.2 kg Se/baand ( Fe)a( 011)6(11Se0a)a applied at 1.62 kg Se/ha. Pointsrepresent means of three replications. Standard error of themean for successive cuttings are 0.188, 0,044, 0.088, 0.232,and 0.120, respectively, including data for both Fig. 1 and 2.were in the desirable range for livestock in all five alfalfacrops (Fig. 2). The (Fe)„(OH) b(HSe03 ), when appliedat a higher rate provided less Se than did the (Fe) (OH) 3,(HSe03 ) E. Evidently Se from (Fe) x(OH),(HSe03) ismore readily available than that from (Fe)„(OH) b(HSe03),. Both materials have potential as slowly avail-able Se sources, but (Fe) a (OH) b (HSe03 ), appears tohave the greater potential because of its tendency to releaseSe at a slower, but adequate rate.These laboratory-prepared bi-selenites may not be thesame as those thought to be present in acid soils (7). Ad-mittedly the compounds used are not well characterized,but neither are those forms present in soils. It is likely thatdifferent preparation procedures would produce com-pounds that differ considerably in their Se availability toplants. Nevertheless, the data reported in this paper indi-cate that compounds can be prepared that will provide aslowly available Se source for plants. How practical thepreparation and use of these materials might be cannot bereadily assessed. Furthermore, since these compoundsappear to offer little advantage over CuSeO5 and possiblyother commercially available selenites, it may be morepractical to use commercially available selenites.In conclusion, the data presented in this paper show thatSe uptake from BaSe04 on an alkaline soil is about the sameas it is from soluble selenates. Addition of sulfate with theselenate may enchance Se uptake. Therefore it is not safeto add selenates to alkaline soils even when mixed withBaSO4 because from these materials plants absorb Se con-centrations toxic to livestock. Selenites can be safely addedto the alkaline soil used in this study. Two ferric hydroxyselenites have potential as long-lasting, slowly availableSe sources for plants, but they have little or no advantageover CuSeOs. The possible advantages of selenites used inthis study in comparison to a very soluble form such asNa2Se03 were not directly determined. The most practicalsource will probably depend upon cost and convenience.Elemental Se can be safely added to the alkaline soil usedbut it is less efficient and therefore more expensive thanselenite sources.718	 SOIL SCI. SOC. AMER. PROC., VOL. 33, 1969LITERATURE CITED1. Allaway, W. H., E. E. Cary, and C. F. Ehlig. 1967. Thecycling of low levels of selenium in soils, plants and ani-mals. In 0. H. Muth (ed.) Selenium in biomedicine.A.V.I. Publishing Co., Westport, Conn. p. 273-296.2. Allaway, W. H., and Earle E. Cary. 1964. Determinationsof submicrogram amounts of selenium in biological ma-terials. Anal. Chem. 36:1359-1362.3. Allaway, W. H., D. P. Moore, J. E. Oldfield, and 0. H.Muth. 1966. Movement of physiological levels of selen-ium from soils through plants to animals. J. Nutr. 88:411-418.4. Carter, D. L., M. J. Brown, W. H. Allaway, and E. E.Cary. 1968. Selenium content of forage and hay cropsin the Pacific Northwest. Agron. J. 60:532-534.5. Cary, Earle E., and W. H. Allaway. 1969. The stabilityof different forms of selenium applied to low seleniumsoils. Soil Sci. Soc. Amer. Proc. 33:571-574.6. Cary, Earle E., George A. Wieczorek, and W. H. Alla-way. 1967. Reactions of selenite-selenium added to soilsthat produce low-selenium forages. Soil Sci. Soc. Amer.Proc. 31:21-26.7. Geering, Harold R., Earle E. Cary, L. H. P. Jones, andW. H. Allaway. 1968. Solubility and redox criteria forthe possible forms of selenium in soils. Soil Sci. Soc.Amer. Proc. 32:35-40.8. Grant, A. B. 1965. Pasture top-dressing with selenium.New Zealand I. Agr. Res. 8:681-690.9. Hamilton, John W., and 0. A. Beath. 1963. Uptake ofavailable selenium by certain range plants. J. Range Man-age. 16:261-264.10. Hurd-Karrer, Annie M. 1935. Factors affecting the ab-sorption of selenium from soils by plants. J. Agr. Res. 50:413-427.11. Hurd-Karrer, Annie M. 1937. Selenium absorption bycrop plants as related to their sulphur requirement. J. Agr.Res. 54:601-608.12. Kubota, J., W. H. Allaway, D. L. .Carter, E. E. Cary, andV. A. Lazar. 1967. Selenium in crops in the United Statesin relation to selenium-responsive disease of animals. Agr.Food Chem. 15:448-453.13. Lakin, H. W. 1961. Selenium content of soils. In Agr.Hdbk. 200, US Dept. Agr. p. 27-34.14. Muth, 0. H. 1963. White muscle disease, a selenium-responsive myopathy. J. Amer. Vet. Med. Assoc. 142:272-277.15. Muth, 0. H., and W. H. Allaway. 1963. The relationshipof white muscle disease to the distribution of naturallyoccurring selenium. J. Amer. Vet. Med. Assoc. 142:1379-1384.16. Ravikovitch, S., and M. Margolin. 1959. The effect ofbarium chloride and calcium sulfate in hindering selen-ium absorption by lucerne. Empire J. Exp. Agr. 27:235-340.17. Underwood, E. J. 1966. The mineral nutrition of live-stock. FAO, United Nations, and Commonwealth Agr.Bureaux. p. 291-330.

Selenium Concentrations in Alfalfa from Several Sources Applied to a Low Selenium, Alkaline Soil

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Selenium Concentrations in Alfalfa from Several Sources Applied to a Low Selenium, Alkaline Soil

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