IJERD – International Journal of Environmental and Rural Development (2017) 8-1

Research article
erd

The Effects of Land Restoration on Soil Fertility in Tsunamiinundated Farmlands of Miyagi Prefecture in JapanKINGSHUK ROY*
College of Bioresource Sciences, Nihon University, Kanagawa, Japan
Email: roy.kingshuk@nihon-u.ac.jp

SATOKI IWATA
Graduate School of Agricultural Science, Tohoku University, Sendai, Miyagi, JapanYURIKA KATO
Geosciences Department, University of Missouri-Kansas City, Missouri, USA
Received 3 February 2017

Accepted 5 May 2017(*Corresponding Author)

Abstract In previous studies, a series of samples were analyzed to measure the salinity status ofagricultural lands in Miyagi prefecture, where the extent of the seawater damage was the most
severe among the tsunami-affected area in Northeast Japan following the Great East Japan
earthquake in 2011. Since then, various restoration projects have been implemented byconcerned agencies of the central and local governments. In the agricultural lands damaged by
the earthquake and flooded with tsunami water, most of the technical tasks, such as the removalof debris and salts and the repair of irrigation and drainage infrastructures, were in the final
stages of completion in 2016, and the efforts seems to have achieved their primary objectives.
However, soil productivity in the restored farmlands remains a big issue for the local farmers.
The present study was carried out in different farmlands in two adjacent towns in Miyagi
Prefecture, Watari-cho and Yamamoto-cho. The major physicochemical and biologicalproperties of soil were investigated, and the results show that the soil dressing used as topsoil in
the restored farmlands had a low average cation exchange capacity (CEC) of <6 cmol(+)kg-1,
which ultimately contributed to lower average CEC values overall (<9 cmol(+)kg-1). Moreover,carbon-to-nitrogen (C:N) ratios in the soil dressings and the restored lands showed a wider
range (5 to 19), making the soil inconsistent in nutrient supply i.e., less fertile, compared tothose in the farmlands where there was no top-dressing and in the farmlands at nearby inlandsites. The study also suggests that issues concerned with rebuilding soil fertility and improving
soil productivity in tsunami-inundated agricultural lands should be resolved through sustainable,soil-friendly methods and practices.
Keywords tsunami, farmland, soil salinity, soil fertility, soil dressing, land restoration

INTRODUCTION
The Great East Japan earthquake and tsunami disaster of 2011 caused massive damages to the coastal
area. The earthquake damaged irrigation and drainage infrastructures severely, while the tsunami
waves inundated large areas of agricultural land, causing excessive saline in the soil. Since theoccurance, a lot of restoration efforts and studies have been carried out in the disaster-affected areas.
Most notably, the central government of Japan announced a comprehensive recovery plan in thedevastated area (Government of Japan, 2012), and accordingly, all concerned ministries, agencies,
prefecture administrations, and non-governmental organizations (NGOs) started restoration projects indifferent sectors. In agricultural lands, salinity was a very big issue soon after the tsunami, especially in
Miyagi prefecture, as this region accounted for nearly two-thirds of the tsunami-inundated agriculturalⒸ ISERD

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IJERD – International Journal of Environmental and Rural Development (2017) 8-1

lands (23,600ha) in northeast Japan (MAFF, 2011). The different stages and the order of execution
related to the restoration, remedial, and reclamation works in agricultural lands consisted of mostly
removing debris, puddling and leaching with freshwater and flushing away salts from the topsoil, andcutting away the top layer and dressing it with new soil carried from a nearby mountain area along withthe rejuvenation of irrigation/drainage infrastructures. Roy et al. (2014, 2015) monitored thespatiotemporal changes in soil salinity in the tsunami-inundated agricultural lands in Miyagi prefecturefrom 2013 to 2015 and concluded that the salinity varied because of several physical factors, such as
topography, soil texture, and water stagnation due to damage to drainage infrastructure. Researchstudies carried out by Tomomasa et al. (2013) and Toyama and Tajima (2014) specified the damage tounderground infrastructures (i.e., buried drainage pipes) as an important factor responsible for waterlogging, poor infiltration, and high salinity. As the restoration works progressed and reached the final
stages of completion in 2016, salinity levels in most areas had returned to pre-tsunami levels (electricalconductivity<1 dS m-1). In addition, the area had enough precipitation (approximately 1,200mm/year) tohelp to mitigate the salinity level even in non-restored lands (NARO, 2013; Roy et al., 2015). However,when crops were cultivated, farmers started to face new problems related to soil productivity in therestored lands.
Soil productivity refers to the capacity of the soil in its normal environment to support plant
growth, while soil fertility refers to the ability of the soil to provide nutrients in proper quantities forthe growth of plants (Gruhn et al., 2000). Therefore, to better understand the potential productivity ofsoil in the restored area, it is important to examine key soil characteristics and indicators—such as soil
texture, depth, pH, organic matter content, and fertility—that might be affected through humanactivities, such as the use of a soil dressing in restoration works, or by natural processes, such as theaccumulation of salt due to seawater intrusion. A report published by the Miyagi Prefecture Furukawa
Agriculture Resaerch Station (2013) showed that the parts of restored paddy fields with a soil dressing
had a reduced average production (361 kg/10a) compared to that of non-restored lands (563 kg/10a).
During prior field surveys from 2013 to 2015, restoration works and farming activities were observed,
and local farmers were interviewed at random about these issues. It is not difficult to understand that,in the case of any sudden replacement of the topsoil with a new soil (soil dressing), the fertility of the
new soil is a big factor that ultimately affects soil productivity. No reports were published to dateindicating that any prior investigations or analyses were completed regarding the fertility status of the
new soil used as the soil dressing in the restored lands in the studied area. This promted further study todetermine the existing soil productivity in terms of the soil fertility in the area. In particular, fieldsamples were collected from different farmlands in two adjacent towns, Watari-cho and Yamamotocho, in Miyagi prefecture, where samples were also collected from 2012 to 2014. Soil samples werecollected from restored farmlands with topsoil dressing (“dressed land”); farmlands with no soil
dressing (“undressed land”); new/mountain soil used in topsoil dressing (“soil dressing”); and inland
farmlands (“inland”) and analyzed for soil fertility.
The aim of this study is to determine the soil fertility in tsunami-inundated farmlands in Miyagi
prefecture, where restoration works have already been completed, as well as to investigate sustainable,soil-friendly methods for agricultural lands where salinity and soil recovery are big issues.
METHODOLOGY
Study Sites and Methods of Sampling
Two adjacent towns, Watari-cho and Yamamoto-cho, both of which accounted for the largest
inundated areas in Miyagi prefecture, were selected as study areas for sampling, although the postdisaster statuses and recovery plans were different in these two sites (Watari-cho, 2015; Yamamotocho, 2015). Field samples were collected and interview surveys were conducted five times fromⒸ ISERD

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December 2014 to December 2015. Fig. 1 presents the sampling sites and sampling points (farmlands)
in the study area. The location of each sampling point were traced by a portable GPS receiver (Garmin
eTrex). It is notable that, in some cases, the land use of the surveyed farmlands (paddy fields/uplands)
as shown in Table 1, differed before and after the tsunami. The sampling points of dressed andundressed lands were randomly selected based on the information gathered during interviews with thelocal farmers. Samples of soil dressing were collected with permission from construction workers at
the study sites. In addition, soil samples were collected from inland farmlands within a distance of 1km from the inundated zone (sampling point) to represent the pre-tsunami soil characteristics of theinundated farmlands. A total of 48 samples were collected from different farmlands in the two
sampling sites: 17 from dressed lands (paddy fields:14, upland:3), 13 from undressed lands (paddy
fields:4, upland:9), 6 from soil dressing, and 12 from inlands (paddy fields:6, upland:6). All soil
samples were collected from the top layer of disturbed soil (upto a depth of 10 cm) by a diagonal
sampling method, packed in polyethylene sacks, and brought back to the laboratory for analysis. Other
related data about land use (paddy, upland, or mountain), land condition (dressed or undressed lands),
plant growth, fertilizer uses, and yields were recorded during interviews with farmers.
A visual outlook of two adjacent farmlands, one a restored land with soil dressing and the otherwith no soil dressing, as presented in Fig. 2, points a clear difference in growth between the two
farmlands.

(Picture taken on June 22, 2015)

Fig. 1 Study sites with sampling locations
Miyagi Prefecture, Japan

Fig. 2 Plant growth in two adjacent paddy fields inat Yamamoto-cho in Miyagi Prefecture

Analysis of Soil Samples
All of the soil samples were processed and analyzed in the laboratories of the College of Bioresource
Sciences at Nihon University. The collected soil samples were air-dried and sieved through a 2 mm mesh,and then select parameters representing key indicators related to soil quality and productivity were
measured. The parameters selected to represent the chemical properties were pH, electrical conductivity(EC), cation exchange capacity (CEC), and exchangeable cations (Ca2+，Mg2+，K+, Na+). The pH (H2O)
and the EC of the soil were measured with a pH meter (Twin pH B-212, Horiba, Japan) and an EC meter(B-173, Horiba, Japan), respectively. The ratio of soil to deionized water was 1:2.5 for pH, and 1:5 for
EC. The CEC, estimated from soil cations (Ca2+ ，Mg2+ ，K+, Na+), was determined by ammonium
acetate method (soil extracted in 1 mol L-1 ammonium acetate (NH4OAc) at a pH 7) and measured with anⒸ ISERD

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atomic absorption spectrophotometer (AA-6680, Shimadzu, Japan). The concentrations of exchangeable
cations, as well as the total exchangeable bases, were then expressed in terms of centi-mol per kg(cmol(+)kg-1). Moreover, basic cation ratios—e.g., calcium-to-magnesium ratio (Ca:Mg), magnesium-topotassium ratio (Mg:K)—and the percent base saturation were also calculated from the amounts of
exchangeable cations analyzed. On the other hand, the selected physical properties were mainly particle
size distribution and soil texture. In addition, gravel content (weight percentage) was also determinedsince the local farmers were worried about an excess of gravel in the soil dressing. The particle size
distribution of the soil was measured using with the pipette method based on Stoke's theorem, and thesoil textural classes were determined according to the IUSS (International Union of Soil Sciences)method. Gravel contents were calculated based on the remnants after sieving the air-dried soil through a
2 mm mesh. For biological properties, total carbon (TC), total nitrogen (TN), carbon-to-nitrogen (C:N)
ratio, and organic matter content (OMC) were measured. The C:N ratio, TC, and TN of the soil were
determined using an NC analyzer (Sumigraph NC-220F, Sumika Chemical Analysis, Japan), while the
OMC of the soil was estimated using with the loss-on-ignition method and a muffle furnace (KBF-748,
Koyo Thermos, Japan). All measured and calculated data regarding soil properties are listed in Table 1.
Statistical Analyses
Descriptive statistics, correlation analyses, and one-way analyses of variance (ANOVA) among thephysicochemical and biological parameters in this study were executed using a Microsoft Office Excel
2013 add-in application.
RESULTS AND DISCUSSION
Chemical Properties of Soil
As presented in Table 1, the average soil CEC values in dressed lands were 8.7 cmol(+)kg-1 and 7.8
cmol(+)kg-1 in Watari-cho and Yamamoto-cho, respectively, whereas those values in undressed lands
were 17.5 cmol(+)kg-1 and 14.9 cmol(+)kg-1, respectively. The inland soil at these two sites had similar
average CEC values at 18.4 cmol(+)kg-1 in Watari-cho and 16.7 cmol(+)kg-1 in Yamamoto-cho. However,average CEC values were much lower for soil dressings at these two sites—5.9 cmol(+)kg-1 and 5.5
cmol(+)kg-1 in Watari-cho and Yamamoto-cho, respectively. Soil from several dressed lands at both sites(sample numbers 14 to 18 and 34 to 36 in Table 1) showed comparatively lower pH values (4.5 to 5.6)
and percent base saturation (17% to 55.4%). However, EC1:5 values in the respective lands werecomparatively higher than in other farmlands. Although CEC and percent base saturation are essential
indicators of soil fertility, the overall balance in exchangeable ions that can be estimated from thenutrient ratios is more important for the nutrient supply to the plants. Fig. 3 and Fig. 4 present the basic
cation ratios (Ca:Mg, Mg:K) in the studied farmlands. The suitable values as recommended by MAFF
(2007) are 2 to 6 for Ca:Mg and 2 to 4 for Mg:K. The nutrient ratios from different farmlands, aspresented in Table 1 and graphed in Fig. 3 and Fig. 4, indicate that, while most of the farmlands’ soils
were within the MAFF-recommended limits, some soil samples collected from the dressed lands(sample 8 and 13 through 18 for Watari-cho, and samples 35, 36, and 39 for Yamamoto-cho in Table
1) had either higher or lower values than the recommended ranges. Such a situation indicates animbalance in nutrition supply in the dressed lands at both Watari-cho and Yamamoto-cho.
Physical Properties of Soil
As presented in Table 1, most of the soil samples (42 out of 48 samples), including each type of lands
in both of the studied areas, were sandy (sandy loam (SL), sand (S), or loamy sand (LS)). The texturalⒸ ISERD

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IJERD – International Journal of Environmental and Rural Development (2017) 8-1

class of 31 soil samples (of 48) was sandy loam (SL), according to the IUSS classification system.
Therefore, the texture of the soil in the study area was generally sandy by nature, regardless of thepresence or absence of top dressing. However, the average particle size distribution showed a tendency
toward fewer fine fractions (silt and clay) in dressed lands than that in undressed and inland lands
because of the abundant gravel contents in the soil dressing—averages of 14.6% and 20.8% in Wataricho and Yamamoto-cho, respectively (Fig. 5).
Biological Properties of Soil
Fig. 6 presents the total C:N ratio of soil, a determinant of organic matter content and an important
indicator for plants’ nutrient availability, at different farmlands in the studied sites. Dividing the C:Nratios into four groups (Fig. 6) shows that most of the soil samples were within the range of 10<C:N<20.
10

10
8

MAFF recommended
range: (2.0 to 6.0)

6

Mg:K ratio

Ca:Mg ratio

8

4

6

MAFF recommended
range : (2.0 to 4.0)

4
2

2

0

0

1 4 7 10 13 16 19 22 25 28 31 34 37 40 43 46

1 4 7 10 13 16 19 22 25 28 31 34 37 40 43 46

Sample number

Sample number

Notes: 1) MAFF: Ministry of Agriculture, Forestry and Fisheries, 2007
2) Sample number: 1 to 27 denote Watari-cho, 28 to 48 denote Yamamoto-cho3) Land use and condition: As presented in Table 1

Fig. 3 Soil Ca:Mg ratios at different farmlands
in Miyagi Prefecture

Fig. 4 Soil Mg:K ratios at different farmlands
in Miyagi Prefecture

0.30

25

5＜C:N ＜10

0.25

20

10＜C:N＜20

C:N＜5

0.20

15

TN (%)

Gravel content (%)

30

10

0.15

5

0.10

0

0.05

C:N＞20(N deficiency)

0.00
0.00
Watari-cho

Yamamoto-cho

Fig. 5 Gravel contents in soils from different
farmlands in Miyagi Prefecture

1.00

2.00

Watari- cho Undressed
DressedSoil dressing
InlandYamamoto- Undressedcho
DressedSoil dressing
Inland3.00

TC (%)

Fig. 6 Total C:N ratios of soils from different
farmlands in Miyagi PrefectureⒸ ISERD

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The C:N ratio in most agriculture soils remains more or less constant; Cleveland (2007) found a
global tendency for the C:N ratio of overall soil to be 14.3±0.5. A soil with a C:N ratio greater than 20
indicates N-deficiency because of microbial growth (JSSSPN, 1998).Although none of the soil samples
in this study had poor C:N values, however, the individual C:N values from the soil dressing and the
dressed lands were highly irregular and scattered across a wider range (5.7 to 18.4) compared to thosein the undressed (10.5 to 15.7) and inland soils (10.1 to 15.8). Moreover, the TC and TN values werealso lower in soil dressings and dressed lands than that in undressed and inland soils. The averagevalues for organic matter content (ignition loss) in the samples of the field soils (dressed, undressed
and inland) ranged within 3.9% to 4.9%, whether the same in the soil dressings showed lower values of
2% and 2.1% in the two study sites.
Soil Properties and Their Correlations
Table 2 presents the correlations between the measured properties of the soil samples collected fromdifferent farmlands in Miyagi prefecture. The correlation matrix also includes the grain-yield factor as
recorded during interviews with farmers at 15 paddy fields with different land conditions. From thetable, the grain yield was found to have strongly correlated (positively and negatively) with soil CEC(r=0.794), clay content (r=0.813), and gravel content (r=-0.87). Moreover, significant correlations
existed between the pH and the base saturation (r=0.889) and EC (r=-0.743); between the EC1:5 andthe base saturation (r=0.739); and between the CEC and the TN(r=0.884), clay (r=0.882), and gravel
contents (r=-0.970). Except for the C:N ratio, most of the measured parameters of the soil samples
that represent the productivity and fertility of the agricultural lands were found to have significantly
correlated to one another (p<0.001, p<0.01, or p<0.05), as presented in the correlation matrix table.
Status of Soil Fertility and Productivity in Restored Lands
While the data and analyses presented above give an idea of soil properties, Fig. 7 shows the yield in2015 at different farmlands in our study sites. As seen in the soil properties, the lands that were
restored with soil dressing (dressed lands) are relatively imbalanced nutritionally and, therefore, lessfertile compared to the undressed and inland fields, which ultimately negatively affects grain yields
at paddy fields with soil dressing in both Watari-cho and Yamamoto-cho, as shown in Fig. 7.
Although fertility does not always guarantee the productivity of soil, it (fertility) represents the
productivity of agricultural lands. Data from Table 1 show that the soils’ CEC and percent basesaturation values were lower overall in dressed lands than in undressed lands, and the extent ofvariation widens when comparing the values from dressed lands with the inlands. The use of soil
Table 2 Correlation matrix between soil properties in Miyagi prefecture
Grain yield
pH(H2O)(Paddy)Grain yield
pH(H2O)
EC1:5

EC1:5

CEC

Exchangeable cations
CaO

MgO

K2O

Base
saturation

TC

TN

C:N ratio

Sand

Silt

Clay

Silt+Clay

Gravelcontent

1.0
0.275-0.660 ***0.794 ***
CEC
0.790 ***
CaO
0.853 ***
MgO
-0.157
K2O
Base saturation 0.310 *
0.749 ***
TC
0.697 ***TN
0.187
C:N ratio-0.705 ***Sand
0.583 ***
Silt
0.813 ***
Clay
0.706 ***
Silt+Clay
Gravel content -0.870 ***1.0-0.743 ***
0.037

1.0
-0.293 *1.0

0.484 *** -0.564 ***0.837 ***

1.0

0.175

-0.484 ***0.916 ***

0.868 ***

1.0

0.116

-0.2510.620 ***

0.576 ***

0.649 ***

1.0

0.889 *** -0.739 ***0.077

0.560 ***

0.321 *

0.264

-0.093-0.1250.902 ***

0.734 ***

0.806 ***

0.485 ***

-0.0481.0-0.043-0.2570.884 ***

0.751 ***

0.817 ***

0.549 ***

0.042

0.904 ***

-0.113

0.325

0.011

-0.069-0.102-0.226-0.2350.201-0.0680.334 *

-0.792 ***-0.659 ***-0.797 ***-0.450 **-0.133-0.704 *** -0.693 *** -0.002

0.079-0.365 *0.685 ***

0.580 ***

0.734 ***

0.382 **

0.165

0.606 ***

0.609 *** -0.047-0.970 ***

1.0

0.052

-0.2170.882 ***

0.720 ***

0.791 ***

0.517 ***

0.050

0.789 ***

0.754 ***

0.102

-0.855 ***0.707 ***

1.0

0.076

-0.340 *0.801 ***

0.669 ***

0.805 ***

0.456 **

0.137

0.712 ***

0.702 ***

0.001

-0.999 ***0.970 ***

0.857 ***

1.0

-0.0490.254-0.734 ***-0.660 ***-0.725 ***-0.302 *-0.072 *-0.757 *** -0.647 *** -0.320 *0.535 *** -0.454 **-0.625 ***-0.545 ***1.0
1.0-0.1931.0
1.0

Significance of correlations indicated by *, **, and ***, are equivalent to p=0.05, p=0.01, and p=0.001 (n=48; only except grain yield, where n=15)Ⓒ ISERD

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IJERD – International Journal of Environmental and Rural Development (2017) 8-1

dressings with a low CEC (4.02 cmol(+)kg-1 to 8.35 cmol(+)kg-1) in the restored lands can be said tobe responsible for that. Because pH and base saturation are generally closely related to soil CEC(Turner and Clark, 1966; Huvlin et al., 2011), even a soil with a high CEC does not guarantee
productivity if the pH is low. In the current study, comparatively lower pH values (4.5 to 5.3) andpercent base saturations (15.67% to 55.49%) were observed in parts of the dressed lands at bothstudy sites (5 lands out of 11 in Watari-cho, and 2 lands out of 6 in Yamamoto-cho), although the EC
were comparatively higher (0.32 dS m-1 to 0.59 dS m-1) in the respective areas. In such case, whilesoil pH needs to be rectified to increase the percent base saturation and thus to enhance the fertility
and favor productivity, farmers were observed using overdoses of fertilizers in these fields, whichmight affect the C:N ratio and increase the EC1:5 of the soil. As a result, while the C:N ratio in mostof the agricultural soil is constant, as found in the inland soil (10 to 12), dressed lands showed
inconstant and wider-ranged values (5 to 19) within the same type of land condition in both study
areas. Lower cation ratios also indicate the inferiority of soil fertility levels in these dressed lands.
All of these chemical properties were found to have strong correlations with the proportion of finer
and the coarser particles from different soils in the study sites. While none of the inland fields had
more than 3.4% gravel contents, the undressed fields contained 6.4% (although there is somepossibility that undressed fields might have some gravel parts carried by the tsunami water), and soil
dressings contained between 14.1% and 25.8%, resulting in maximum percentages of 21.1% gravel
content in dressed lands. During the survey, many volunteers were observed periodically sorting out
gravel at the restored farmlands. All of these factors and activities individually and jointly
deteriorated the nutritional balance and fertility of the soil in these specific lands.

Grain yield (kg m -2)

6

5

4

3
Undressed ｜ Dressed ｜Inland｜Undressed｜Dressed ｜Inland
Watari-cho
Yamamoto-cho
Sampling site

Fig. 7 Yields from paddy fields at different farmlands
in Miyagi Prefecture (2015)
CONCLUSIONS
Several years have passed since the Great East Japan earthquake and tsunami disaster of 2011, and thetsunami-inundated farmlands have been influenced by many natural and anthropological activities.
Therefore, to figure out the absolute status of fertility and productivity in the fields before and after thetsunami is very difficult. Soil samples from nearby inland fields were collected and analyzed of toprovide an idea of the pre-tsunami soil quality in the area.
The analytical results indicate that soil in the restored (dressed) lands is inferior from theperspective of agricultural production compared to the non-restored (undressed) land. The extent ofthat inferiority becomes more distinct when compared with the soil inland, and the reason lies in thequality (or inferiority) of new soil used as a top dressing during the restoration. The findings of thisstudy conclude that, in the tsunami-inundated agricultural fields, the presence of a soil dressing (i.e.,Ⓒ ISERD

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mountain soil) with inferior physical properties (i.e., fewer fine fractions) contained poor andimbalanced chemical and biological constituents, making it less fertile, which ultimately affected soil
productivity even after the restoration. It may take several years or even decades for the topsoil toregain its productivity, and the process can be accelerated only by proper fertility management after
figuring out the specific cause(s) and extent(s) in the specific field(s).
This study also serves to remind that, in the case of agricultural practices with long-term histories andprocesses, rapid land restoration does not necessarily ensure land productivity, which is the most important tofarmers and agriculturists. ‘Slow but steady’ mitigation processes, such as phytoremediation by using
halophytes (Yaneshita, 2011), would be much more practical because the latter does not damage theinherent soil fertility in agricultural fields. Instead, over-fertilization will not only worsen the soil quality
but also have drastic side-effects on soil and natural environment in the long run.
More detailed analyses considering more spatiotemporal data on soil humus, isotopes, and buried
geology could give a clearer picture of the overall fertility and productivity in the area after the tsunami
disaster. Future studies related to salinity mitigation in agricultural fields should include research using
different inexpensive and locally originated materials, such as cotton waste, charcoal, fly ash, andhalophyte species, all of which have salt removing potentials and are harmless to agricultural soils
which is a precondition to sustainable agriculture.
ACKNOWLEDGEMENTS
The authors would like to express gratefulness to the local farmers in Miyagi prefecture, who werevery kind and cooperative throughout the study period. Prof. Yukihiro Hayashi at the College of
Bioresource Sciences at Nihon University in Japan provided valuable suggestions. Thanks are due tothe students of the International Environment Conservation Lab at the College of Bioresource Sciencesat Nihon University for their support in carrying out the experiments and sample analyses.
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