This article was downloaded by: [Northeastern University]On: 11 October 2014, At: 02:11Publisher: Taylor & FrancisInforma Ltd Registered in England and Wales Registered Number: 1072954 Registered office: MortimerHouse, 37-41 Mortimer Street, London W1T 3JH, UK

Acta Agriculturae Scandinavica, Section B — Soil &Plant SciencePublication details, including instructions for authors and subscription information:http://www.tandfonline.com/loi/sagb20

Assessment of seafood processing wastes asalternative sources of Selenium in plant productionTrine A. Sogn a , Espen Govasmark b , Susanne Eich-Greatorex a , Anne Falk-Øgaard a &John A. MacLeod ca Department of Plant and Environmental Sciences , Norwegian University of LifeSciences , Aas, Norwayb The Norwegian Centre for Ecological Agriculture , Tingvoll, Norwayc Agriculture and Agri-Food Canada , Charlottetown, PEI, CanadaPublished online: 12 Apr 2007.

To cite this article: Trine A. Sogn , Espen Govasmark , Susanne Eich-Greatorex , Anne Falk-Øgaard & John A. MacLeod(2007) Assessment of seafood processing wastes as alternative sources of Selenium in plant production, Acta AgriculturaeScandinavica, Section B — Soil & Plant Science, 57:2, 173-181, DOI: 10.1080/09064710600768277

To link to this article: http://dx.doi.org/10.1080/09064710600768277

PLEASE SCROLL DOWN FOR ARTICLE

Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) containedin the publications on our platform. However, Taylor & Francis, our agents, and our licensors make norepresentations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose ofthe Content. Any opinions and views expressed in this publication are the opinions and views of the authors,and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be reliedupon and should be independently verified with primary sources of information. Taylor and Francis shallnot be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and otherliabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to orarising out of the use of the Content.

This article may be used for research, teaching, and private study purposes. Any substantial or systematicreproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in anyform to anyone is expressly forbidden. Terms & Conditions of access and use can be found at http://www.tandfonline.com/page/terms-and-conditions

ORIGINAL ARTICLE

Assessment of seafood processing wastes as alternative sources ofSelenium in plant production

TRINE A. SOGN1, ESPEN GOVASMARK2, SUSANNE EICH-GREATOREX1,

ANNE FALK-ØGAARD1 & JOHN A. MACLEOD3

1Department of Plant and Environmental Sciences, Norwegian University of Life Sciences, Aas, 2The Norwegian Centre for

Ecological Agriculture, Tingvoll, Norway and 3Agriculture and Agri-Food Canada, Charlottetown, PEI, Canada

AbstractIn some parts of the world, the soil selenium (Se) content is too low to ensure the Se level recommended for human oranimal consumption in the crops produced. In order to secure a desired concentration of Se in crops, Se has been applied asmineral fertilizer to agricultural fields. Since only a minor part of the inorganic Se applied is utilized by plants and smallincreases in Se concentrations in, e.g., drinking water, may be toxic, the method is somewhat controversial. As an alternativeto Se-enriched mineral fertilizer, different seafood-processing wastes have been examined as a source for Se in cropproduction. Both in greenhouse pot experiments and field trials the Se in seafood waste was not plant-available during thefirst growing season. There was no significant difference between the Se concentration in wheat growing in soil withoutadded Se and in soil receiving Se from seafood waste in amounts ranging from 0.9 to 9 g ha�1. Neither was any residualeffect of Se in seafood waste seen during a second year growth period. Thus, seafood-processing waste cannot be regarded asa potential source of Se in crop production. Possible mobilization of formerly applied Se, as seafood-processing waste or Seenriched mineral fertilizer due to changes in soil redox conditions were examined in a leaching experiment. The mobility offormerly applied Se was generally very low, but the results indicated that under permanently wet soil conditions leaching ofSe may occur in plant dormant periods in soils with low organic matter content and high pH.

Keywords: Plant-available selenium, seafood waste, selenium leaching, soil selenium, wheat.

Introduction

The trace element selenium (Se) is of fundamental

significance for human and animal health, foremost

as an important constituent of the antioxidant

enzyme gluthatione peroxidase. In parts of the

world, particularly in large areas of Scandinavia

(Wu & Lag, 1988; Gissel-Nielsen et al., 1984), in

Finland (Varo et al., 1988), in New Zealand (Gupta

& Watkinson, 1985) and in eastern Canada (Gupta

& Winter, 1975) plant availability of Se in soils is

very low. Thus, crops produced in these areas have a

very low Se concentration (Gupta & Winter, 1975;

Gissel-Nielsen et al., 1984; Gupta & Watkinson,

1985; Varo et al., 1988; Govasmark et al., 2005). In

order to ensure that the Se concentration in plants

reaches recommended levels of 0.1 to 0.2 mg kg�1

dry matter for humans and 0.2 to 0.3 mg kg�1 for

livestock, Se-enriched mineral fertilizers have been

used in crop production (Varo et al., 1988; Eurola

et al., 1989; Ekholm, 1997). However, results from

different trials show that only a limited part of the

added Se is utilized by plants (Mikkelsen et al.,

1989; Ylaranta, 1990; Ekholm et al., 1995; Bakken

& Ruud, 2000). Also, the residual effect has shown

to be very small (Singh, 1991). Between 70 and 90%

of the inorganic Se applied seemed to accumulate in

soil in forms not available for plants. It is still not

fully understood whether the applied Se will remain

immobile in the soil, or if changes in soil environ-

mental factors may cause mobilization. If mobilized,

the excess of the applied Se represents a potential

environmental problem since relatively small in-

creases in Se may result in toxic concentrations. A

Se concentration of 10 mg l�1 is usually regarded as

Correspondence: T. A. Sogn, Department of Plant and Environmental Sciences, Norwegian University of Life Sciences, P.O. Box 5003, N-1432 Aas, Norway.

Tel: �/47 64965565. E-mail: trine.sogn@umb.no

Acta Agriculturae Scandinavica Section B-Soil and Plant Science, 2007; 57: 173�181

(Received 12 January 2006; accepted 18 April 2006)

ISSN 0906-4710 print/ISSN 1651-1913 online # 2007 Taylor & Francis

DOI: 10.1080/09064710600768277

Dow

nloa

ded

by [

Nor

thea

ster

n U

nive

rsity

] at

02:

11 1

1 O

ctob

er 2

014

the maximum acceptable for drinking water. For

instance, elevated Se concentrations in ground water

have been associated with leaching from agricultural

land in California (White et al., 1991), and thus Se

contamination of drinking water is of concern

(Hudak, 2004). It would evidently be safer to find

a Se source that is more bioavailable than inorganic

fertilizer enriched with Se. In organic farming, where

use of such fertilizer is restricted, alternative Se

sources must be found. Plants have been shown to

take up organic Se compounds, such as the amino

acid Se methionine (SeMet), in nutrient solution

experiments (Lauchli, 1993). In animal feeding

experiments, organic Se sources, such as SeMet or

selenoyeast, proved to be more bioavailable than

inorganic Se sources (Pehrson et al., 1989; Wang &

Lovell, 1997; Ortman, 1999). Organic Se sources

may therefore be an alternative to the inorganic Se

additives also in plant production. Fish and crusta-

ceans generally have a high Se content. Fish Se

concentration normally ranges between 0.10 and

1.90 mg kg�1 and crustacean Se concentration

between 0.20 and 2 mg kg�1. In addition, feed for

fish farming is usually enriched with Se in order to

ensure optimal mineral supplement and thereby

good fish health. In order to recycle a waste product

and thus utilize Se that already exists in the food

chain, seafood-processing waste may be evaluated as

a Se source in plant production. If positive results are

gained, the waste may be used as an ultimate Se

source within organic farming and as a desirable

alternative to the Se-enriched manufactured mineral

fertilizer within traditional plant production.

In this study, three different seafood-processing

wastes were assessed as Se sources in wheat produc-

tion both in greenhouse and field studies. Addition-

ally, the mobility of the Se not taken up by plants was

investigated in a leaching experiment with different

redox conditions prior to leaching. The hypotheses

to be tested were that: 1) Se-rich seafood-processing

waste, applied as an organic fertilizer, increases

wheat grain Se concentration; 2) oxidizing soil

conditions followed by reducing soil conditions

(heavy irrigation) may induce leaching of formerly

applied Se from soil.

Material and methods

The field experiment in Canada

A field study with wheat (Belvedere) cultivation and

organic Se fertilizer treatments consisting of two

different lobster wastes was established at the

Harrington research farm, Prince Edward Island,

Canada (6389?W, 46820?N). The site is situated

about 40 m above sea level with an annual precipita-

tion ranging from 800 to 1100 mm. The soil is a fine

sandy loam classified as a Typic Haplorthod in Soil

Taxonomy. The soil contained 3.1% (w/w) organic

matter in the plough layer and the pH was 6.5

(H2O, 1:1). The natural soil Se content was about

0.22 mg kg�1 (Gupta & Winter, 1975), and the

grain yields produced in this area have an average Se

concentration of 0.05 mg kg�1 (MacLeod et al.,

1998). The treatments were laid out in a randomized

block design with four replicates. The plot size was

20 m2 (5 m�/4 m) with a 2 m border around, and a

harvested area of only 0.36 m2. The levels of Se

applied with lobster waste ranged from 0.9 to 9 g

ha�1 (Table II). No mineral fertilizer was applied in

addition to the lobster waste, or to the control plots.

The grain crop was harvested at maturity, dried at

608C, and analysed for Se by a method described

below.

As Se fertilizer, fresh and composted waste was

applied to the soil. Chemical characteristics of the

two wastes are presented in Table I. For analysis of

most elements, except Se, samples of the lobster

waste (1 g) were digested in 12 ml HNO3 in a

microwave. The sample solution which evaporated

to 5 ml in the process, was diluted to 50 ml with

H2O and then centrifuged (3500 r.p.m. for 10 min)

before an aliquot was transferred to an 8-ml tube

and analysed by ICP optical emission spectroscopy

(ICP-OES). The lobster and grain samples were

analysed for total Se concentration by the recently

developed method of Govasmark and Grimmet

(2006). Briefly, 1 g of sample was digested in closed

Teflon vessels in the microwave using ultra-pure

HNO3 and 30% H2O2. Se in the digested solution

was reduced by concentrated HCl, derivatized with

2,3-diaminonaphthalene, and then extracted into

Table I. Chemical characteristics of the fish silage and the fresh and composted lobster waste.

Macronutrients (g kg�1 DM) Trace elements (mg kg�1 DM)

C:N N P K S Ca Mg Na Fe Zn Mn Cu B Co Se Al

Fish silage 3.8 11.4 20.5 11.5 10.4 23.7 2.6 16.3 530 590 10 40 nd1 nd1 0.90 30

Fresh lob. waste 6.2 42.3 16.1 3.0 3.3 158 8.7 6.6 336 45 259 24 29 0.26 0.45 382

Composted lob. waste 22.5 13.2 8.0 3.0 1.7 113 5.7 3.4 4437 37 301 23 15 1.94 0.34 8439

1nd�/not determined.

174 T.A. Sogn et al.

Dow

nloa

ded

by [

Nor

thea

ster

n U

nive

rsity

] at

02:

11 1

1 O

ctob

er 2

014

cyclohexane. This solution was analysed for Se on a

high performance liquid chromatograph (HPLC)

equipped with a fluorescence detector. The method

was validated with a suite of reference materials.

The field experiment in Norway

A field experiment with cultivation of spring wheat

(Triticum aestivum L.) and different Se fertilizer treat-

ments was carried out at As, Norway (10845?E,

59840?N). The annual precipitation in this area is on

average about 800 mm. The experimental site is

situated about 70 m a.s.l. on a marine clay deposit.

The soil is a loam, classified as a Typic cryaquept in

Soil Taxonomy. The soil pH is about 5.8 (H2O,

1:2.5), and the organic matter content in the plough

layer about 5.3% (w/w). The natural soil Se content

is 0.29 mg kg�1 (Ruud, 1997). Plants growing in

this soil usually have a Se concentration B/0.02 mg

kg�1 (Ruud, 1997). Thus, a very small fraction of

the total soil Se pool is plant-available. As Se

supplement, the soil was applied Se-rich fish silage

(Table I) or Se-enriched NPK fertilizer ((21:3:8)

with 12 mg Se kg�1 as Na2SeO4). The Se concen-

tration in the fish silage was analysed by hydrid

generation atomic absorption spectrophotometry

(Perkin Elmer 1100-B) after digestion in HNO3

and Mg(NO3)2, ashed at 4508C and resolved in

HCl. The N concentration was determined by using

a CHN analyser (LECO EC-12) and the concen-

trations of other elements were analysed by use

of inductively-coupled plasma mass spectrometry

(ICP-MS) after microwave digestion.

The treatments were laid out in a randomized

block design with four replicates. The plot size was

21 m2 (3 m�/7 m), with a harvested area of 10 m2.

Each Se treatment plot received a total amount of Se

corresponding to 9 g ha�1, divided into 8 g Se ha�1

at the start of the experiment and 1 g Se ha�1 at

Zadoks stage 21 (Zadoks et al., 1974), i.e., at

tillering. The Se-treated plots were compared to

control plots without any added Se. In the control

treatment, a basic dose of NPK fertilizer (21:4:10)

corresponding to 140 kg N ha�1 was applied prior

to sowing. At Zadoks stage 21, a top dressing with

NPK corresponding to 18 kg N ha�1 was applied.

The Se-enriched (as NaSeO4) NPK fertilizer was

applied in an amount corresponding to the same

amount of N as in the control. In order to adjust for

the imbalance in P and K, the amounts of these

elements were adjusted with superphosphate and

KCl. To achieve the same amount of Se as in the

NPK�/Se (as Na2SeO4) treatment, 9514 kg fish

silage was applied per ha. To adjust for the N in the

fish silage (Table I), the amount of NPK fertilizer

(21:4:10) was reduced by 10 kg N ha�1 compared to

the amount used in the other treatments. The crop

was harvested at maturity. Grain samples were dried

and ground before digestion with strong acid

(HNO3) in an autoclave. The plant material was

analysed for Se by a high-resolution inductively-

coupled plasma mass spectrometry (HR-ICP-MS).

The pot experiment in Norway

A greenhouse pot experiment with wheat (Triticum

aestivum L.) growing in two different soil types was

conducted. The soil types were a commercial growth

peat and a loam soil taken close to where the field

experiment was carried out. In order to establish two

different pH levels, approximately 5.5 (pHlev 1) and

6.5 (pHlev 2), the soil was limed with different

amounts of CaCO3, depending on initial and in-

tended pH. The pH values found after the growth

period were, however, somewhat different from the

intended ones; pHlev 1 represented pH values

ranging from 4.8 to 5.5 in the peat, and from 4.5

to 5.4 in the loam, while pHlev 2 represented values

from 6.1 to 6.8 in the peat, and values from 5.8 to

6.3 in the loam.

The Se treatments were equivalent to those

conducted in the field experiment described above,

given as fish silage or Se-enriched NPK fertilizer.

There were seven replicates per treatment, three of

which were used for analysis at the end of the

experiment. Four pots were used in the leaching

experiment. The pot volume was 6.7 l. Moisture

content in the soil was maintained at 60% of field

capacity by regular irrigation with deionized water.

The crop was harvested at maturity. Grain and straw

Se concentrations were measured by use of HR-ICP-

MS after digestion with strong acid (HNO3) in an

autoclave.

In order to examine a possible residual effect,

three pots from the fish silage treatment were kept

for a second year growth experiment. All the pots

received NPK fertilizer as in the control, and no new

fish silage was added � otherwise the experiment ran

exactly similar to the first year.

Table II. Fresh and composted lobster waste and the correspond-

ing Se applied per m2 in the Canadian field experiment.

Se mg m�2

Applied kg plot�1 Fresh Silageed

0

5 0.113 0.085

10 0.225 0.170

20 0.450 0.340

40 0.900 0.680

Selenium in seafood processing wastes 175

Dow

nloa

ded

by [

Nor

thea

ster

n U

nive

rsity

] at

02:

11 1

1 O

ctob

er 2

014

Four pots within each treatment from the first year

growth experiment were used in a leaching study in

order to examine if some of the Se that accumulated

in the soil from Se fertilization could be mobilized

due to changes in soil redox conditions. The leaching

experiment was divided, and in two replicates per

treatment, the soil was homogenized after harvest,

dried and remoistened to field capacity after 20 days,

while the soil in the two other replicates was kept

undisturbed and constantly moist at 60% of field

capacity. After 20 days also these pots were mois-

tened to field capacity. To simulate a heavy rainfall,

1 l distilled H2O was added to the pots in four doses

of 250 ml each, and the leachate was collected after

24 h. Se concentration in the leachate was analysed

by HR-ICP-MS.

Statistics

Treatment effects on plant Se concentration and

uptake, as well as soil pH and Se concentrations in

leachate were tested by analysis of variance and

multiple testing using the General Linear Model

(GLM) procedure and the Student- Neuman-Keul’s

(SNK) test of SAS (SAS Institute Inc. statistical

software). The differences were considered signifi-

cant at the p B/0.05 level.

Results and discussion

Experiment in Canada

In the Canadian field experiment, fresh and com-

posted lobster waste, in amounts ranging from 0.25

to 2 kg m�2, were used as Se source. Neither the

grain yield nor the grain Se concentration was

significantly affected by the Se-rich lobster waste

application (Figure 1). The grain yield was on

average 459, 517, and 497 g m�2 for the control,

fresh lobster waste, and composted lobster waste

treatments, respectively, and the average grain Se

concentrations were 0.13, 0.15, and 0.13 mg kg�1 in

the same treatments. The soil pH was not altered by

the lobster waste application. The lobster waste

decomposition process had led to a higher C:N ratio

and to somewhat lower concentrations of most

elements except for Fe, Al, Co, and Mn in the

composted waste relative to the fresh (Table I). The

higher C:N ratio in the decomposed waste (Table

III) could have influenced enhanced microbial im-

mobilization of Se. However, the Se in lobster waste,

independent of waste decomposition degree and

C:N ratio seems to be little plant-available, and

cannot be regarded as a potential source of Se in

crop production, at least not in the same growing

season as the application.

Experiments in Norway

Average grain yield in the field experiment in Nor-

way was 338 g m�2 and there were no significant

differences in grain yield between the treatments. As

expected, according to the low C:N ratio (Table I),

the fish silage represented a source of plant avai-

lable N during the growing season. There was no

significant difference in grain Se concentration ob-

served between the fish silage treatment (0.0119/

0.008 mg kg�1 DM) and the control (0.0139/

0

0.1

0.2

0 5 10 20 40 0 5 10 20 40

Fresh lobster waste Composted lobster waste

Se

mg

kg-1

DM

kg lobster waste applied per plot (20 m2)

Figure 1. Grain Se concentration in control (0) and after application of increasing amounts (5�40 kg per 20 m2) of fresh and silaged lobster

waste in the Canadian field experiment.9/St. dev. of the average is indicated by the bars, n�/ 4.

176 T.A. Sogn et al.

Dow

nloa

ded

by [

Nor

thea

ster

n U

nive

rsity

] at

02:

11 1

1 O

ctob

er 2

014

0.008 mg kg�1 DM). Thus, the Se in fish silage was

not plant-available in the first growing season. On

the other hand, Se application via the NPK fertilizer

resulted in significantly higher Se concentration in

grain (0.2109/0.023 mg kg�1 DM) compared to

grain from fish silage and control plots. The Se

concentration in the wheat grain produced in soil

fertilized with NPK-Se reached the recommended

Se level in grain for animal feed and human bread

flour (0.1�0.2 mg kg�1). As percent of Se added,

the amount of Se found in the grain was, however,

only 7.2%.

In general, the results from the pot experiment

supported the finding from the field experiment in

that the Se from fish silage was not plant-available

during the first growing season, whereas application

of Se-enriched NPK fertilizer significantly increased

the plant concentration of Se (Figure 2). The straw

and grain Se concentrations in plants grown in soil

supplied with fish silage were not significantly

different from the control. Neither soil pH nor the

varying content of soil organic matter had any

significant impact on this result. Neither was there

any significant effect of Se treatment on plant growth

in the pot experiment. As seen in the field experi-

ment, and also as expected according to the low C:N

ratio (Table I), the fish silage represented a source of

plant available N during the growing season. How-

ever, reduced plant growth was observed in the loam

soil at the lowest pH level (pH 4.5). Estimated plant

Se uptake (straw Se concentration*straw weight�/

grain Se concentration*grain weight) (Table III)

revealed that in the case of wheat plants grown in

loam at pHlev 1 (i.e., pH 4.5), the higher plant Se

concentration was apparently a result of this reduced

growth. Up to almost 32% of the applied Se was

taken up by plants in the greenhouse experiment

(Table III). This figure is higher than the Se

utilization usually reported from field experiments

(Mikkelsen et al., 1989; Ylaranta, 1990; Ekholm

et al., 1995; Bakken & Ruud, 2000). The higher

plant and root density in the pot experiment has

apparently led to a better utilization of the applied Se

than in field.

The residual effect of inorganic Se fertilization has

shown to be of little importance in plant production

(Singh, 1991). The decomposition of fish silage in

soil is most probably not completed during the first

growing season and release of Se from seafood waste

decomposition in soil may partly occur in the plant-

dormant periods and coming growth seasons. In our

study the amount of residual Se from the fish silage

taken up by plants in the second growth season was

almost negligible (Figure 2; Fish_2 yr). Results from

a ten-year study with Se-rich sewage sludge applica-

tion, published by Edelbauer and Eder (2001)

showed no significant residual effect of added Se

via sludge. The application of sewage sludge induced

increased Se content in the upper 0�5 cm of soil,

while no significant increase in plant Se concentra-

tion was found. Thus, the residual effect of Se added

via organic waste products seemed to be as limited as

for Se enriched mineral fertilizer. The Se released in

the plant dormant period has, probably, quite

rapidly been transformed to forms strongly adsorbed

in soil. Perhaps the addition of organic matter has

induced enhanced binding of Se as well. The plant

concentration (Figure 2) and plant uptake of Se

(Table III) is often lower when fish silage is applied

than in the control treatment (not significant). pH

measurements in soil after harvest show a slightly

lower pH (not significant) in the pots applied fish

silage compared to the control. As plant availability

of Se generally decreases with decreasing soil pH,

this pH reduction may explain the lower plant

uptake of Se when fish silage is applied. Additionally,

Lee (1997) demonstrated excellent binding proper-

ties of sea food processing waste for phosphate,

which is an anion like selenate and selenite. Johnsson

(1991) and Gustafsson and Johnsson (1992) found

added mineral Se to be strongly bound to soil

organic matter. When the process was further

investigated, the Se retention seemed to be primarily

due to microbially mediated reductive incorporation,

whereby the Se anions are reduced to low valence

states and then incorporated into low-molecular-

weight humic substance fractions (Gustafsson &

Johnsson, 1994). They claimed further abiotic sorp-

tion of Se in organic matter to be important only as a

‘trapping’ mechanism for dissolved Se, but quanti-

tatively unimportant in the storage process. How-

ever, the effect of organic matter on Se availability in

soil is somewhat inconsistent. Winja and Schulthess

(2000) found that presence of organic acids as

oxalate and citrate inhibited adsorption of Se by

competition for the anion binding sites and thus in-

duced more labile and plant-available Se in the soil.

Leaching experiment

More information on the environmental fate of Se

applied to crops in Se-deficient areas has been

requested (e.g., MacLeod et al., 1998). At low pH

and reducing conditions, Se occurs mainly in the

form of selenite, whereas in oxidizing soil conditions

combined with higher pH the more mobile selenate

prevails. By studying distribution of Se in paddy soils

(rice fields) where oxidation and reduction occur

repeatedly, Kang et al. (1991) detected Se enrich-

ment in the lower soil horizons. In a similar way, but

to a lesser extent, we assume that ploughing com-

bined with a dry weather period may induce oxida-

Selenium in seafood processing wastes 177

Dow

nloa

ded

by [

Nor

thea

ster

n U

nive

rsity

] at

02:

11 1

1 O

ctob

er 2

014

tion and remobilization of the soil-bound Se. If the

dry period is suddenly ended by heavy rainfall,

leaching of the remobilized Se may occur. Owing

to these assumptions, the leaching experiment in-

cluded physical disturbance and drying before the

actual leaching event. In the loam at pHlev 2,

significantly higher leaching of Se was found from

pots with soils being permanently wet than those

being dried before the leaching event. For all the

others, no significant differences were found be-

tween the pots exposed to physical disturbance and

drying and those kept permanently wet with regard

to Se leaching (Figure 3), independent of Se treat-

ment. Our hypothesis that oxidizing soil conditions

followed by reducing soil conditions (heavy irriga-

tion) may induce leaching of formerly applied Se

from soil was not verified. Rather, the results

indicated that leaching of applied Se may occur in

plant dormant periods, under permanently wet soil

conditions, in soil with low organic matter content

and high pH. Similar to the results regarding plant

availability, the Se applied to the soil as Se-enriched

NPK fertilizer showed significantly higher mobility

than the Se applied via fish silage (Figure 3), whereas

the latter did not differ from the control treatment.

Although significantly higher than the leaching

of Se from the control and fish silage treatments,

the leaching of Se from the pots with Se enriched

NPK was not alarming. The maximum Se concen-

tration measured in the leachate was 5.1 mg l�1.

Table III. Se applied, plant Se uptake and calculated plant Se utilization (%) during the first growth season in the greenhouse pot

experiment. Means (n�/ 3) followed by the same letter are not significantly different (p B/0.05).

Soil pHlev Treatment

Se applied

(mg pot�1)

Plant Se uptake

(mg pot�1)

Plant Se utilization

(%)*

Peat 1 Control 0 1.39a

NPK-Se 30 10.86b 31.56a

Fish silage 30 0.57a �/2.71b

2 Control 0 2.95a

NPK-Se 30 6.89b 13.11a

Fish silage 30 1.36a �/5.32b

Loam 1 Control 0 0.41a

NPK-Se 30 2.64b 7.46a

Fish silage 30 1.19a 2.61b

2 Control 0 1.32a

NPK-Se 30 9.31b 26.64a

Fish silage 30 0.91a �/1.37b

*((Plant Se uptake treatment � Plant Se uptake control)/Se applied in treatment) *100.

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

Con

trol

Fis

h

Fis

h_2y

r

NP

K_S

e

Con

trol

Fis

h

Fis

h_2y

r

NP

K_S

e

Con

trol

Fis

h

Fis

h_2y

r

NP

K_S

e

Con

trol

Fis

h

Fis

h_2y

r

NP

K_S

e

Peat, pHlev 1 Peat, pHlev 2 Loam, pHlev 1 Loam, pHlev 2

Se

mg/

kg D

M

Straw Grain

Figure 2. Grain and straw Se concentration [mg kg�1] in the greenhouse pot experiment. Fish_2yr denotes the second year residual effect

study of the fish silage treatment.9/St. dev. of the average is indicated by the bars, n�/ 3. The treatment abbreviation used along the

horizontal axis mean: ‘Fish’�/Fish silage, ‘Fish_2yr’�/ residual Fish silage (second yr) and ‘NPK_Se’�/Se enriched NPK fertilizer.

178 T.A. Sogn et al.

Dow

nloa

ded

by [

Nor

thea

ster

n U

nive

rsity

] at

02:

11 1

1 O

ctob

er 2

014

This concentration is below 10 mg l�1, which is

generally regarded as the maximum acceptable Se

concentration for drinking water.

As mentioned above, there was a trend (not

significant) towards lower plant uptake of Se when

Se-rich fish silage was added compared with the

control treatment. In the leaching experiment there

was also a trend (not significant) towards lower

concentrations of Se in leachate from the pots

receiving fish silage than in the control treatment.

This may indicate that addition of organic matter has

reduced soil Se mobility. However, the effect of

organic matter application on soil Se mobility or

availability of applied mineral Se must be verified by

batch or column experiments.

Although the plant utilization of the applied Se

(organic or inorganic) varied in our experiments, the

general low plant uptake and the low leaching found

leave no doubt that application of Se (organic or

inorganic) will increase the soil total Se pool. Never-

theless, it is difficult to trace the additional Se in soil.

Within Scandinavia, Finland is the country practis-

ing the most liberal Se fertilization policy, and Se has

been applied to agricultural soils since 1985. This

fertilization practice has been accompanied by stu-

dies on long-term effects of the Se fertilization.

Usually less then 10% of the applied Se is found to

be taken up by the crop (Yli-Halla, 2005), and no

sign of increased Se concentration in surface waters

has been found (Wang et al., 1994). Comparison

of water-extractable Se in soil before the start of

application (Sippola, 1979) and after 14 years of

application gave no significant increases (Makela-

Kurtto & Sippola, 2002). In soil samples from 48

fields at ten different research stations in Finland,

sampled in 1994 and 2004, no significant changes

were found in aqua regia-extractable Se (Yli-Halla,

2005). No obvious environmental effects connected

to the Se-fertilization practices have been detected to

date (Alfthan & Aro, 2005). However, the interval

between deficiency and toxicity for Se is very tight.

For instance, elevated Se concentrations in ground-

water have been associated with leaching from

agricultural land in California (White et al., 1991),

and thus Se contamination of drinking water is of

concern (Hudak, 2004). Although the leaching of Se

from the pots with Se-enriched NPK in our experi-

ment was lower than the maximum acceptable Se

concentration for drinking water, the fact that it was

significantly higher than in the control treatment

should support use of a precautionary principle. As

important as establishing agronomic practice secur-

ing recommended levels of Se in food plants, is the

search for practices improving the plants’ utilization

of applied mineral Se, as well as Se sources which

have a higher utilization degree than Se enriched

mineral fertilizer.

Conclusions

The hypothesis that Se-rich seafood processing

waste increases wheat grain Se concentration when

Figure 3. Se concentration [mg l�1] in the leachate in the greenhouse experiment.9/St. dev. of the average is indicated by the bars, n�/ 2.

Each of the four groups of bars is linked to the soils loam or peat, each at different pH levels (pH lev). The abbreviations used on the bars

mean: ‘Contr.-ox’�/Control treatment, with drying. ‘Contr.-red’�/Control treatment, with constant wet soil conditions. ‘Fish-ox’ and

‘Fish-red’�/Fish silage treatment, with respectively drying or constant wet conditions. ‘NPK-Se-ox’ and ‘NPK-Se-red’�/Treatment with Se

enriched NPK fertilizer, with drying or constant wet conditions, respectively.

Selenium in seafood processing wastes 179

Dow

nloa

ded

by [

Nor

thea

ster

n U

nive

rsity

] at

02:

11 1

1 O

ctob

er 2

014

applied to soil as a fertilizer, was not verified. There

was no significant difference between the Se con-

centration in wheat growing in soil without added

Se and in soil receiving Se in amounts from 0.9 to

9 g ha�1 as seafood waste. Nor was any residual

effect of the Se added as seafood waste found during

a second growth season. The hypothesis that oxidiz-

ing soil conditions followed by reducing soil condi-

tions (heavy irrigation) may induce leaching of

formerly applied Se from soil was not verified.

Rather the results indicated that leaching of applied

Se may occur under permanently wet soil conditions

in plant dormant periods, in soil with low organic

matter content and high pH.

References

Alfthan, G., & Aro, A. (2005). Environmental effects of selenium

fertilization � is there a potential risk? In M Eurola (Ed.),

Twenty years of Selenium fertilization . (pp.33�35). Agrifood

Research Reports 69 .

Bakken, A.K., & Ruud, L. (2000). Mineralinnhald i gras gjødsla

med selenhaldig Fullgjødsel. Kvithamardagene 2000. Grønn

forskning 05/2000. Planteforsk, pp.120. (In Norwegian.)

Edelbauer, A., & Eder, G. (2001). Auswirkung unterschie-

dlicher Dungungsmassnamen in Dauergrunland auf den

Selengehalt in Boden und im Aufwuchs. Die Bodenkultur ,

52 , 209�214.

Ekholm, P., Ylinen, M., Koivistoinen, P., & Varo, P. (1995).

Selenium concentration of Finnish foods: effects of rendu-

cing amount of selenate in fertilizers. Agricultural Science in

Finland , 4 , 377�384.

Ekholm, P. (1997). Effects of selenium-supplemented commercial

fertilizer on food selenium contents and selenium intake in

Finland, Univesity of Helsinki EKT series 1047, p. 74.

Eurola, M.P., Ekholm, P., Ylinen, M., Koivistoinen, P., & Varo, P.

(1989). Effects of selenium fertilization on the selenium

content of selected Finnish fruits andvegetables. Acta Agri-

culturae Scandinavica , 39 , 345�350.

Gissel-Nielsen, G., Gupta, U.C., Lamand, M., & Westermarck, T.

(1984). Selenium in soils and plants and its importance in

livestock and human nutrition. Advances in Agronomy, 37 ,

398�453.

Govasmark, E., & Grimmet, M.G. (2006). A microwave digestion

method for determination of selenium in organic tissue using

liquid chromatography. Journal of AOAC International ,

Accepted.

Govasmark, E., Steen, A., Strøm, T., Hansen, S., Singh, B.R., &

Bernhoft, A. (2005). Statusof selenium and vitamin E on

Norwegian organic sheep and dairy cattle farms. Acta

Agriculturae Scandinavica Section A Animal Sciences , 55 ,

40�46.

Gupta, U.C., & Winter, K.A. (1975). Selenium content of

soils and crops and the effects of lime and sulphur on

plant selenium. Canadian Journal of Soil Science , 55 , 161�166.

Gupta, U.C., & Watkinson, J.H. (1985). Agricultural significance

of selenium. Outlook on Agriculture , 14 , 183�189.

Gustafsson, J.P., & Johnsson, L. (1992). Selenium retention in the

organic matter of Swedish forest soils. Journal of Soil Science ,

43 , 461�472.

Gustafsson, J. P., & Johnsson, L. (1994). The association between

selenium and humic substances in forested ecosystems �

laboratory evidence. Applied Organometallic Chemistry, 8 ,

141�147.

Hudak, P.F. (2004). Boron and selenium contamination in south

Texas groundwater. Journal of Environmental Science and

Health , 39 , 2827�2834.

Johnsson, L. (1991). Selenium uptake by plants as a function of

soil type, organic matter content and pH. Plant and Soil , 133 ,

57�64.

Kang, Y., Nozato, N., Kazutake, K., & Yamada, H. (1991).

Distribution and forms of selenium in paddy soil. Soil Science

and Plant Nutrition , 37 , 477�485.

Lauchli, A. (1993). Selenium in plants: uptake, functions, and

environmental toxicity. Botanica Acta , 106 , 455�468.

Lee, S.M. (1997). Phosphate removal by wasted sludge of

cuttlefish processing factory. Proceedings of the international

Symposium on environmental engineering , POST ECH,

Kyungju, Korea.

MacLeod, J.A., Gupta, U.C., Milburn, P., & Sanderson, J.B.

(1998). Selenium concentration in plant material, drainage

and surface water as influenced by Se applied to barley

foliage in a barley-red clover-potato rotation. Canadian

Journal of Soil Science , 78 , 685�688.

Makela-Kurtto, R., & Sippola, J. (2002). Monitoring of Finnish

arable land: changes in soil quality between 1987 and 1998.

Agricultural and Food Science in Finland , 11 , 273�284.

Mikkelsen, R.L., Page, A., & Bingham, F.T. (1989). Factors

affecting selenium accumulation by agricultural crops. In

Selenium in agriculture and environment . (pp. 65�93).

SSSA special publication No 23 SSSA and ASA, Madison,

WI.

Ortman, K. (1999). Organic vs. inorganic selenium in farm

animal nutrition with special reference to supplementation

of cattle. Doctoral thesis. Swedish University of Agricultural

Sciences, Uppsala. ISSN 1401�6257. p. 51.

Pehrson, B., Knutsson, M., & Gyllensward, M. (1989). Glu-

tathione peroxidase activity in heifers fed diets supplemented

with organic and inorganic selenium compounds. Swedish

Journal of Agricultural Research , 19 , 53�56.

Ruud, L. (1997). Forsøksrapport 1997. Samarbeidsprosjekt IJVF �Norsk Hydro ASA . Rapport nr. 6/1997 (56). ISSN 0805-

7214. p. 89 (In Norwegian.)

SAS Institute Inc. statistical software (http://support.sas.com/rnd/

app/).

Singh, B.R. (1991). Selenium content of wheat as affected by

selenate and selenite contained in a Cl� or SO42�( based

NPK fertilizer. Fertilizer Research , 30 , 1�7.

Sippola, J. (1979). Selenium content of soils and timothy (Phleum

pratese L.) in Finland. Annales Agriculturae Fenniae , 18 ,

182�187.

Varo, P., Alfthan, G., Ekholm, P., Aro, A., & Koivistionen, P.

(1988). Selenium intake and serum selenium in Finalnd:

effects of soil fertilization with selenium. American Journal of

Clinical Nutrition , 48 , 324�329.

Wang, D., Alfthan, G., Aro, A., Lahermo, P., & Vaananen, P.

(1994). The impact of selenium fertilization on the distribu-

tion of selenium in rivers in Finland. Agriculture Ecosystems &

Environment , 50 , 133�149.

Wang, C., & Lovell, R.T. (1997). Organic selenium sources,

selenomethionine and selenoyeast, have higher bioavalability

than an inorganic selenium source, sodium selenite, in diets

for channel catfish (Ictalurus punctatus ). Aquaculture , 152 ,

223�234.

White, A.F., Benson, S.M., Yee, A.W., Wollenberg, H.A. Jr., &

Flexser, S. (1991). Ground water contamination at the

Kesterson Reservoir, California. 2. Geochemical parameters

influencing selenium mobility. Water Resources Research , 27 ,

1085�1098.

180 T.A. Sogn et al.

Dow

nloa

ded

by [

Nor

thea

ster

n U

nive

rsity

] at

02:

11 1

1 O

ctob

er 2

014

Winja, H., & Schulthess, C.P. (2000). Interaction of carbonate

and organic anions with sulphate and selenate adsoption on

an aluminium oxide. Soil Science Society of America Journal ,

64 , 898�908.

Wu, X., & Lag, J. (1988). Selenium in Norwegian farmland soils.

Acta Agriculturae Scandinavica , 38 , 271�276.

Ylaranta, T. (1990). The selenium content of some agricultural

crops and soils before and after the addition of selenium to ferti-

lizers in Finland. Annales Agriculturae Fenniae , 29 , 131�139.

Yli-Halla, M. (2005). Influence of selenium fertilization on soil

selenium status. Proceedings. In M Eurola (Ed.), Twenty

years of Selenium fertilization. (pp.25�32). Agrifood Research

Reports , 69 .

Zadoks, J.C., Chang, T.T., & Konzak, C.F. (1974). A decimal

code for the growth stages of cereals. Weed Research , 14 ,

415�421.

Selenium in seafood processing wastes 181

Dow

nloa

ded

by [

Nor

thea

ster

n U

nive

rsity

] at

02:

11 1

1 O

ctob

er 2

014