A icle
Cen ennial Fe iliza ion-Induced Soil P ocesses
Con ol T ace Me al Dynamics. Lessons om a
Long-Te m Ba e Fallow Expe imen
Folke an Oo 1,*, Remigio Pa adelo 2ID , Nicolas P oix 3, Ghislaine Dela ue 1, Denis Baize 4
and Fab ice Monna 5
1INRA-Ag oPa isTech, UMR 1402 EcoSys, Soil Eco oxicology, RD10, F-78026 Ve sailles CEDEX, F ance;
[email p o ec ed]
2Facul ade de Fa macia, Depa amen o de Eda oloxía e Química Ag ícola, Uni e sidade de San iago
de Compos ela, E-15782 San iago de Compos ela, Spain; [email p o ec ed]
3INRA, US 0010 Labo a oi e d’Analyse des Sols, 273 Rou e de Camb ai, F-62000 A as, F ance;
[email p o ec ed]
4INRA, UR 0272 Science du Sol, F-45075 O léans CEDEX 2, F ance; [email p o ec ed]
5
Uni e si éde Bou gogne—F anche Com é, UMR 6298, A TéHis, CNRS-Cul u e, 6 bd Gab iel, Bâ . Gab iel,
F-21000 Dijon, F ance; [email p o ec ed]
*Co espondence: [email p o ec ed]; Tel.: +33-130-833-251
Recei ed: 15 Ma ch 2018; Accep ed: 17 Ap il 2018; Published: 19 Ap il 2018
Abs ac :
Long- e m ba e allow (LTBF) expe imen s wi h his o ical sample a chi es o e unique
oppo uni ies o s udy long- e m impac s o an h opogenic ac i i ies on mine al soil ac ions.
In na u al
ag o- and ecosys ems, such impac s a e o en masked by o ganic ma e due o i s
bu e ing ac ion and apid u no e . The 42-plo LTBF ial o INRA (Ins i u Na ional de la Reche che
Ag onomique) s a ed in Ve sailles (F ance) in 1928 o assess he impac s o p olonged applica ion o
e ilize s and amendmen s on he composi ion and p ope ies o loamy soils. He e, we es ablished
geochemical budge s o majo and ace elemen s on su ace samples om 1929 and 2014 o ou
g oups o ea men s ele an o de eloped soil p ocesses. We conside ed accompanying e ec s o
soil compac ion o decompac ion due o changing physicochemical condi ions o e 85 yea s. Elemen
losses om he su ace ho izon we e quan i ied ia e iliza ion-induced o -ampli ied soil p ocesses:
clay leaching a o ed by Na- o K-based e iliza ion, and lixi ia ion o majo and ace elemen s
in acidic o alkaline soil condi ions. Enhanced mine al wea he ing was shown o acidi ied and
nonamended plo s. Conclusions on ace me al mig a ion we e con i med by selec ed analyses on
subsu ace ho izons. Addi ional in o ma ion was p o ided on speci ic elemen inpu s ia e ilize s
and/o di use inpu s ia a mosphe ic deposi ion.
Keywo ds:
e iliza ion; ba e allow soils; long- e m ag onomic expe imen s; loess Lu isol; acidi ica ion;
lixi ia ion; clay leaching; geochemical budge s; majo elemen s; ace me als
1. In oduc ion
Soil deg ada ion o , be e , deg ada ion o soil p ope ies may esul om bo h an h opogenic
ac i i ies and na u al p ocesses, i.e., land misuse, soil mismanagemen , o clima ic change and ela ed
ac o s [
1
]. Soil acidi ica ion was an up- o-da e opic in he 1970s o 1990s wi h a iew o acid
ain and ela ed isks o inc eased leaching o soil nu ien s. Cu en ly, soil o ganic ca bon (SOC)
pools occupy a cen al place in p oblema ic global change, wi h espec o educed biodi e si y,
dec eased agg ega e s abili y and soil compac ion, and nu ien loss [
1
,
2
]. Such i ems a e widely
documen ed. The SOC pool was epo ed as he de ining cons i uen o soil [3] and epu ed o be he
Soil Sys . 2018,2, 23; doi:10.3390/2020023 www.mdpi.com/jou nal/soilsys ems
Soil Sys . 2018,2, 23 2 o 20
mos eliable indica o o moni o ing soil deg ada ion [
4
], pa icula ly by soil e osion.
This epu a ion
is due, in la ge pa ,
o sho - e m
esponse on clima ic o an h opogenic cons ain s and apid
u no e dynamics in
soils [5,6]
. Howe e , in mos ecosys ems, he decomposi ion o o ganic ma e is
compensa ed by es i u ion o plan deb is o o ganic e iliza ion and amendmen s in ag icul u al
soils. The e o e,
soil o ganic
ma e (SOM) is no necessa ily he mos sui able indica o o long- e m
cons ain s a ec ing soils, o in any case no he sole indica o . Changing land use and managemen o
ag icul u al p ac ices may also a ec he soil’s mine al ac ion, in pa icula he ines eac i e phases.
Phyllosilica e clay mine als egis e such impac s by changes in hei composi ion (subs i u ion),
beha io (hyd a ion), su ace p ope ies (elec ic cha ge), o clay-pa icle hickness [
7
–
9
]. The chemical
and mine alogical e olu ion o clay mine als is gene ally less apid han ha o SOC pools. Impac s o
long- e m an h opogenic ac i i ies on mine al ac ions a e less well documen ed, because s udy in
eal ield condi ions is o en hampe ed by soil he e ogenei y, changing land use, managemen p ac ices,
o du a ion o ield moni o ing.
Long- e m ag onomic expe imen s a e pa icula ly aluable o s udying ime impac s o
ag icul u al managemen on soils and cul i a s, unde mo e o less known and/o con olled
condi ions. Among hem, long- e m ba e allow (LTBF) expe imen s, in he absence o ege a ion and
o ganic ma e es i u ion, o e unique oppo uni ies o un a el he complex impac s o an h opogenic
ac i i ies on mine al soil ac ions. In 1928, such a long- e m ag onomic expe imen , simply designa ed
as he “42-plo s ial,” was c ea ed a he esea ch cen e o INRA (Ins i u Na ional de la Reche che
Ag onomique) in Ve sailles, loca ed in he ga dens o he Cha eau de Ve sailles. The main ini ial
objec i e was o “examine he impac s o p olonged applica ions o main N, P and K e ilize s,
as well as o ganic and basic amendmen s on he composi ion and p ope ies o loam soils” [
10
].
The expe imen
was conduc ed on ba e soils, in he absence o ege a ion. Fe ilize doses we e abou
wice hose applied in he 1930s [
10
]. Such condi ions a e mo e ex eme han hose obse ed in eal
ield si ua ions, bu we e in en ionally selec ed o exace ba e he impac s o he di e en ea men s on
mine al soil ac ions. The es ic ed su ace o he expe imen in a ai ly la geog aphical posi ion
ensu ed he simila i y o soils and soil p ope ies a he s a o he expe imen . Mo eo e , he his o ical
soil a chi e o annually collec ed su ace samples makes i possible o s udy ime e ec s, such as SOM
dynamics [
11
] o a mosphe ic deposi ion o me al pollu an s [
12
,
13
]. O ganic C and N dynamics in he
42 plo s ha e been ex ensi ely discussed elsewhe e [11,14,15].
Recen ly, soil damage e ec s o chemical e iliza ion o in ensi ely cul i a ed soils in mode n
indus ialized ag icul u e in he ques o e e -inc easing p oduc i i y we e ques ioned in an a icle
i led “Why I ’s Time o S op Punishing Ou Soils wi h Fe ilize s” [
16
]. Such ques ioning implies
disposing o good indica o s o ime e ec s o e iliza ion p ac ices on soils. S udy o long- e m
ba e allow ials p o ides aluable insigh in o e ilize -induced impac s on soils. The aim o he
p esen wo k was o in e p e , om a pedological poin o iew, ecen ly ob ained analy ical da a on
soils o he LTBF 42-plo s ial o INRA Ve sailles. We es ablished geochemical budge s o majo and
ace elemen s co e ing a ime span o 85 yea s and assessed he impac s o e iliza ion ea men s
on he composi ion and p ope ies o loess Lu isols. Fo ha , we selec ed su ace soil samples
collec ed in 1929 and 2014 in plo s unde mono alen (Na, K), ammonium-based, d ied blood, o basic
amendmen ea men s, and in nonamended plo s, hus o e ing a wide panel o physicochemical
soil condi ions. Geochemical budge s we e examined in e ms o inpu s by e ilize s, amendmen s,
and a mosphe ic
deposi ion, o losses ia e iliza ion-induced soil p ocesses. Selec ed explo a o y
da a on soil cha ac e is ics in subsu ace ho izon a e b ie ly discussed o suppo he majo indings o
ou wo k wi h espec o mig a ion pa hways o majo and ace elemen s owa d soil dep h.
Soil Sys . 2018,2, 23 3 o 20
2. Ma e ials and Me hods
2.1. Long-Te m Ba e Fallow Expe imen o INRA Ve sailles
The expe imen was conduc ed on sil -loam ex u ed Haplic Lu isols [
17
] de eloped in loess,
ep esen a i e o la ge a eas used o con en ional ce eal p oduc ion in no he n F ance and
no hwes e n Eu ope. The expe imen was and s ill is managed acco ding o a s ic plan, unchanged
since 1928: plo s a e 2 m
×
2.5 m wide; annual inpu s o N- e ilize s a e in he sp ing, whe eas K and
P e ilize s, as well as o ganic and basic amendmen s, a e added in au umn; he uppe 25 cm soil
o all plo s is dug by spade wice a yea , ollowing e iliza ion; 16 e iliza ion ea men s a e es ed
in duplica e and 10 plo s emain wi hou applica ions as a e e ence. Weeds a e emo ed manually
and occasionally by he bicide ea men . The i s applica ions we e pe o med on 12 No embe 1928.
Samples o he uppe 25 cm su ace laye ha e been collec ed h oughou he expe imen , gene a ing
oday a 90-yea -old unique ba e-soil sample a chi e.
Ini ial soil da a used in ou wo k we e aken om [
10
]: pH 6.3, and bulk densi y es ima ed
a
1300 kg/m3
based on soil po osi y da a. Ini ial chemical da a we e de e mined on he i s
e e ence-plo samples collec ed in Ma ch 1929: clay con en : 189 g/kg and concen a ions o majo
and ace elemen s [
18
,
19
]. The e ilize s used we e comme cial p oduc s. The e ilize s ocks we e
enewed pa ly in 1954 and comple ely in 1991. The applied doses o he a ge elemen s N, P, K,
and Ca
we e adap ed acco ding hei concen a ion in he e ilize s, bu li le o no in o ma ion on he
con en s o ace elemen s was a ailable.
The expe imen al design o he 42 plo s is p esen ed in Figu e 1. Fo he p esen s udy,
26 plo s we e selec ed and di ided in o 4 g oups wi h compa able analy ical cha ac e is ics:
(1) ammonium-based
e ilize s (sul a e, phospha e, chlo ide, ni a e) and d ied blood; esul s
indica ed by ed ba s (o spo s) and black bo de s; (2) mono alen Na- and/o K-based e ilize s
added as sul a e, chlo ide, o ni a e; o he sodic ea men s, he esul s a e indica ed by yellow ba s
wi h ed bo de s; (3) e e ence plo s, 4 om he le -hand ni ogen block ( e e ence L) and 4 om he
igh -hand K, P, and basic amendmen s block ( e e ence R); esul s indica ed by g ay ba s wi h black
bo de s; and (4) basic amendmen s, indica ed by g een ba s wi h black bo de s. The samples om
plo s along a small oad in sigh o he INRA’s esea ch cen e (19–21,40–42) we e excluded om ou
s udy due o suspec ed localized dus con amina ion [19].
Soil Sys . 2018, 2, x FOR PEER REVIEW 3 o 20
2. Ma e ials and Me hods
2.1. Long-Te m Ba e Fallow Expe imen o INRA Ve sailles
The expe imen was conduc ed on sil -loam ex u ed Haplic Lu isols [17] de eloped in loess,
ep esen a i e o la ge a eas used o con en ional ce eal p oduc ion in no he n F ance and
no hwes e n Eu ope. The expe imen was and s ill is managed acco ding o a s ic plan,
unchanged since 1928: plo s a e 2 m × 2.5 m wide; annual inpu s o N- e ilize s a e in he sp ing,
whe eas K and P e ilize s, as well as o ganic and basic amendmen s, a e added in au umn; he
uppe 25 cm soil o all plo s is dug by spade wice a yea , ollowing e iliza ion; 16 e iliza ion
ea men s a e es ed in duplica e and 10 plo s emain wi hou applica ions as a e e ence. Weeds a e
emo ed manually and occasionally by he bicide ea men . The i s applica ions we e pe o med
on 12 No embe 1928. Samples o he uppe 25 cm su ace laye ha e been collec ed h oughou he
expe imen , gene a ing oday a 90-yea -old unique ba e-soil sample a chi e.
Ini ial soil da a used in ou wo k we e aken om [10]: pH 6.3, and bulk densi y es ima ed a
1300 kg/m
3
based on soil po osi y da a. Ini ial chemical da a we e de e mined on he i s
e e ence-plo samples collec ed in Ma ch 1929: clay con en : 189 g/kg and concen a ions o majo
and ace elemen s [18,19]. The e ilize s used we e comme cial p oduc s. The e ilize s ocks we e
enewed pa ly in 1954 and comple ely in 1991. The applied doses o he a ge elemen s N, P, K, and
Ca we e adap ed acco ding hei concen a ion in he e ilize s, bu li le o no in o ma ion on he
con en s o ace elemen s was a ailable.
The expe imen al design o he 42 plo s is p esen ed in Figu e 1. Fo he p esen s udy, 26 plo s
we e selec ed and di ided in o 4 g oups wi h compa able analy ical cha ac e is ics: (1)
ammonium-based e ilize s (sul a e, phospha e, chlo ide, ni a e) and d ied blood; esul s indica ed
by ed ba s (o spo s) and black bo de s; (2) mono alen Na- and/o K-based e ilize s added as
sul a e, chlo ide, o ni a e; o he sodic ea men s, he esul s a e indica ed by yellow ba s wi h ed
bo de s; (3) e e ence plo s, 4 om he le -hand ni ogen block ( e e ence L) and 4 om he
igh -hand K, P, and basic amendmen s block ( e e ence R); esul s indica ed by g ay ba s wi h black
bo de s; and (4) basic amendmen s, indica ed by g een ba s wi h black bo de s. The samples om
plo s along a small oad in sigh o he INRA’s esea ch cen e (19–21,40–42) we e excluded om ou
s udy due o suspec ed localized dus con amina ion [19].
Figu e 1. Expe imen al design o he 42-plo s ial, g oups o selec ed plo s wi h hei colo codes,
and equi alen annual e ilize inpu a es pe hec a e. Whi e plo s we e no conside ed in his
wo k.
In addi ion o global sampling in he su ace ho izon, bulk and undis u bed samples we e also
collec ed in he unde lying E, B and C ho izons o a dozen plo s, using a oo auge de ice (diame e
8 cm, heigh 15 cm), un il he ca bona ed pa en ma e ial was eached, be ween 90 and >120 cm. The
co e samples we e sepa a ed acco ding soil ho izon limi s. Selec ed undis u bed pa s we e
esin-imp egna ed be o e hin-sec ion p epa a ion; he es we e g ound o 2 mm and s o ed o
Figu e 1.
Expe imen al design o he 42-plo s ial, g oups o selec ed plo s wi h hei colo codes,
and equi alen
annual e ilize inpu a es pe hec a e. Whi e plo s we e no conside ed in his wo k.
In addi ion o global sampling in he su ace ho izon, bulk and undis u bed samples we e also
collec ed in he unde lying E, B and C ho izons o a dozen plo s, using a oo auge de ice (diame e
8 cm, heigh 15 cm), un il he ca bona ed pa en ma e ial was eached, be ween 90 and >120 cm.
The co e samples we e sepa a ed acco ding soil ho izon limi s. Selec ed undis u bed pa s we e
Soil Sys . 2018,2, 23 4 o 20
esin-imp egna ed be o e hin-sec ion p epa a ion; he es we e g ound o 2 mm and s o ed o
chemical analysis. Rele an chemical and mic oscopic da a a e p esen ed, p o iding a i s sho
o e iew o he impac s o 85 yea s o expe imen a ion on soil cha ac e is ics in subsu ace ho izons,
which suppo s ou in e p e a ion o geochemical budge s es ablished in he 0–25 cm su ace ho izons.
2.2. Analysis o Soil Cha ac e is ics and To al Elemen Concen a ions
On ep esen a i ely qua e ed soil samples om he selec ed plo s, he ollowing analyses we e
pe o med acco ding o in e na ional s anda d condi ions [
20
]: g ain size dis ibu ion (NF X 31-107),
pH in wa e (ISO 10390), o ganic ca bon and ni ogen (ISO 10694, ISO 13878), and ca ion exchange
capaci y (CEC) and exchangeable ca ions by he cobal hexammine me hod (ISO 23470). Fo analysis
o o al elemen concen a ions, subsamples we e g ound o 250
µ
m be o e comple e dissolu ion by
hyd o luo ic and pe chlo ic acid (ISO NF X31-147). Majo ag onomic elemen s (K, P, Ca, Mg, and Na),
pedological key indica o elemen s (Al, Fe, and Mn), and 12 ace elemen s—mic o-oligo-elemen s
(Cu, Zn, Co, C , Ni, Mo, and As) and nonessen ial elemen s (Cd, Pb, U, Tl, and Sc)—we e de e mined
by ei he Induc i ely Coupled Plasma A omic Emission Spec ome y (ICP-AES) o Mass Spec ome y
(ICP-MS) (NF ISO 22036 and NF ISO 17294-2, espec i ely). To al elemen concen a ions we e
analyzed simul aneously on samples om 1929 and 2014. The s udied elemen s we e chosen based on
a p elimina y analy ical sc eening o 25 elemen s in soils o he 42 plo s. Ou inal selec ion coincides o
a la ge ex en wi h he panel o majo and ace elemen s conside ed in a la ge F ench na ional esea ch
p og am on ace me al con en s in ag icul u al soils [21].
2.3. Compu a ion o Elemen S ocks and Budge s
Following decomposing o ganic ma e and di e ging physicochemical ambience induced by
e iliza ion, he physical p ope ies o soils in he su ace ho izon we e signi ican ly modi ied, no ably
wi h ega d o soil s uc u e, agg ega e s abili y, and bulk densi y [
2
,
22
,
23
]. Among he plo s selec ed
o ou wo k, he bulk densi ies in 2014 a ied om abou 1200 o 1600 kg/m
3
, i.e.,
≈
30% a ia ion
wi h espec o he es ima ed 1300 kg/m
3
a he s a o he expe imen . Consequen ly, he weigh
o 1 m
2
o he 25 cm hick Ap ho izon anged om
≈
300 o 400 kg. In iew o such di e ences,
he use
o elemen concen a ions exp essed as mass pe kg o soil does no app op ia ely accoun o
hei amoun s in he su ace ho izon. The e o e, we calcula ed s ocks o elemen s in he 0–25 cm Ap
ho izons, exp essed as mass pe m
2
. The use o elemen s ocks was epo ed as an ecologically ele an
uni o soil quali y s udies [
24
,
25
], p e en ing biased compa isons o elemen amoun s in soils wi h
a iable bulk densi y, o ganic ma e con en , o ho izon hickness [
26
]. S ocks o elemen s in a soil
ho izon we e calcula ed by mul iplying he elemen concen a ion, he bulk densi y, and he ho izon
hickness. Thus, in 1929 he ini ial s ock o elemen s (S1929) in he Ap ho izon was:
S1929 = [M]1929 ×ρ1929 × Ap (1)
whe e [M]
1929
= elemen concen a ion (mass/kg), de e mined on Ma ch 1929 e e ence-plo samples;
ρ1929 = bulk densi y (kg/m3) o he Ap ho izon in 1929; and Ap = hickness o Ap, se o 0.25 m.
Fo 2014, he compu a ion o elemen s ock was mo e complex. Fi s , due o he combining e ec s
o soil compac ion and successi e soil collec ion, and a cons an 25 cm dep h o annual digging and
sampling, he uppe cen ime e s o he unde lying E ho izon was p og essi ely inco po a ed in o he
su ace Ap ho izon (Figu e 2). Second, a small bu nonnegligible pa o he su ace ho izon elemen s
is cu en ly s o ed in he soil a chi e collec ion. The e o e, in 2014 he elemen s ock (S
2014
) in he Ap
ho izon included 3 e ms:
S2014 = S’2014 −SE+ Sa ch (2)
S’2014: o e all elemen s ock (kg/m3) in he 25 cm su ace laye = [M]2014 ×ρ2014 ×0.25
Soil Sys . 2018,2, 23 5 o 20
whe e [M]2014 = elemen concen a ion (mass/kg) and ρ2014 = bulk densi y; and
SE: elemen s ock om he E ho izon inco po a ed in o he Ap ho izon
= [M]E1929 ×ρE×( E1 + E2)/100
whe e [M] = elemen concen a ion (mass/kg) in he uppe ew cm o he E ho izon in 1929,
se o
he
ini ial su ace ho izon concen a ion;
ρE
= bulk densi y (kg/m
3
) o he E ho izon, se o
1580 kg/m3
acco ding o se e al local soil su ey s udies [
27
,
28
]; and
E
= hickness (cm) o he E ho izon
inco po a ed in o he su ace Ap ho izon, wi h:
E1: hickness linked o densi ica ion in he Ap ho izon = [(ρ2014 −ρ1929)×0.25]/ρE/100
E2: hickness linked o soil sampling, es ima ed a 75 kg o 5 m2= (75/5)/ρE/100
Soil Sys . 2018, 2, x FOR PEER REVIEW 5 o 20
SE: elemen s ock om he E ho izon inco po a ed in o he Ap ho izon
= [M]E1929 × ρE × ( E1 + E2)/100
whe e [M] = elemen concen a ion (mass/kg) in he uppe ew cm o he E ho izon in 1929, se o he
ini ial su ace ho izon concen a ion; ρE = bulk densi y (kg/m3) o he E ho izon, se o 1580 kg/m3
acco ding o se e al local soil su ey s udies [27,28]; and E = hickness (cm) o he E ho izon
inco po a ed in o he su ace Ap ho izon, wi h:
E1: hickness linked o densi ica ion in he Ap ho izon
= [(ρ2014 − ρ1929) × 0.25]/ρE/100
E2: hickness linked o soil sampling, es ima ed a 75 kg o 5 m2 = (75/5)/ρE/100
The es ima ion o 75 kg o soil collec ed o each plo is based on he ac ual amoun s s o ed in
he his o ical sample a chi e, and p obably sligh ly unde es ima es he amoun o soil used wi h
ime o labo a o y analyses. The e o e, E2 was se o 1 cm.
Sa ch: elemen s ock o he Ap in he his o ical sample collec ion
= (75/5) × ([M]2014 + [M]1929)/2
The inal geochemical budge o each elemen is calcula ed as:
B2014−1929 = S2014 − S1929 (3)
Figu e 2. E ec s o soil deepening o heigh ening (Δep ) o he 0–25 cm laye due o changing bulk
densi y caused by e ilizing ea men s (Δep) and epe i i e soil sampling (Δ’ep) since 1929. The
manu e ea men is added he e o demons a e he ampli ude o soil heigh (modi ied a e [19]).
NB: Fo ea men s wi h dec easing bulk densi y du ing he expe imen (d ied blood, lime), he
soil su ace ose, p oducing a new laye be ween he Ap and E ho izons, Ap/E. This e ec was
pa icula ly isible o he manu e ea men (Figu e 2), whe e he su ace Ap bulk densi y
dec eased o 960 kg/m3 [2,19]. The co esponding elemen s ock SA/E was calcula ed using a e age
alues o elemen concen a ions and bulk densi ies be ween 1929 and 2014:
SA/E: = ([M]1929 + [M]2014)/2 × (ρ2014 + ρ1929)/2 × ( A/E1 + A/E2)/100
whe e A/E1 = [(ρ2014 − ρ1929) × 0.25]/[(ρ2014 + ρ1929)/2]/100 and A/E2 is se o 1 cm. NB: AE1 and AE2 ha e
opposi e signs, hus exp essing a soil ising o deepening e ec , espec i ely.
Figu e 2.
E ec s o soil deepening o heigh ening (
∆ep
) o he 0–25 cm laye due o changing bulk
densi y caused by e ilizing ea men s (
∆ep
) and epe i i e soil sampling (
∆
’
ep
) since 1929.
The manu e
ea men is added he e o demons a e he ampli ude o soil heigh (modi ied a e [19]).
The es ima ion o 75 kg o soil collec ed o each plo is based on he ac ual amoun s s o ed in he
his o ical sample a chi e, and p obably sligh ly unde es ima es he amoun o soil used wi h ime o
labo a o y analyses. The e o e, E2 was se o 1 cm.
Sa ch: elemen s ock o he Ap in he his o ical sample collec ion
= (75/5) ×([M]2014 + [M]1929)/2
The inal geochemical budge o each elemen is calcula ed as:
B2014−1929 = S2014 −S1929 (3)
NB: Fo ea men s wi h dec easing bulk densi y du ing he expe imen (d ied blood, lime),
he soil su ace ose, p oducing a new laye be ween he Ap and E ho izons, Ap/E. This e ec was
pa icula ly isible o he manu e ea men (Figu e 2), whe e he su ace Ap bulk densi y dec eased
Soil Sys . 2018,2, 23 6 o 20
o 960 kg/m
3
[
2
,
19
]. The co esponding elemen s ock S
A/E
was calcula ed using a e age alues o
elemen concen a ions and bulk densi ies be ween 1929 and 2014:
SA/E: = ([M]1929 + [M]2014)/2 ×(ρ2014 +ρ1929)/2 ×( A/E1 + A/E2)/100
whe e
A/E1
= [(
ρ2014 −ρ1929
)
×
0.25]/[(
ρ2014
+
ρ1929
)/2]/100 and
A/E2
is se o 1 cm. NB:
AE1
and
AE2 ha e opposi e signs, hus exp essing a soil ising o deepening e ec , espec i ely.
2.4. Validi y o Calcula ions
The alidi y o ou compu a ion app oach was checked by compa ing budge s o one soil
componen , a key indica o o dominan soil p ocesses (<2
µ
m clay ac ion), and one ace elemen
(scandium, Sc), assuming hei concomi an mig a ion in loess Lu isols. This hypo hesis was
based i s on he geochemis y li e a u e om he 1960s and 1970s: (i) in e omagnesian mine als,
Sc
3+
can subs i u e o Fe
3+
and Al
3+
[
29
]; (ii) in sedimen a y soils, scandium is p ima ily loca ed in
easily wea he able mine als, such as ho nblende, bio i e, and chlo i e [
30
]; and (iii) in Lu isols o
No h Ame ica, Sc ansloca ion was shown o be closely ela ed o clay and i on ia pedogenesis
p ocesses [
29
]. Second, Sc is dissemina ed a li le o no a all by an h opogenic ac i i y in he
en i onmen [
31
] and has e y low mobili y in soils unde oxidizing and acidic en i onmen al
condi ions [
32
]. Thi d, ou p e ious wo k [
19
] e ealed ema kably high co ela ion be ween Sc and
clay o he en i e soil se o he 42-plo s expe imen (Figu e 3a, excluding manu e plo s), suppo ing
he li e a u e indings. The Sc con en in clay ac ions, analyzed on samples om plo s wi h highly
con as ing physicochemical condi ions, showed an a e age o 18.4
±
0.37 mg/kg. Such low a iabili y
o he Sc con en o clay makes i use ul as an indica o o clay loss/accumula ion.
The s ocks o <2
µ
m clay ac ions and scandium we e es ablished ollowing
Equa ions (1) and (2)
o he selec ed g oups o e iliza ion ea men s (c . Figu e 1) and hei geochemical budge s we e
es ablished ollowing Equa ion (3). Compa ing he co ela ion o concen a ions and budge s o
scandium and clay (Figu e 3a,b) e eals an app eciable inc ease o R
2
om 0.83 o 0.92. In bo h
g aphs, he slopes o linea eg ession we e e y close o measu ed clay Sc con en s (18.4 mg/kg),
17.6 and 17.3
, espec i ely. Fo plo s displaying clea ly lowe clay con en in 2014, i.e.,
≥
20%
since 1929
,
he budge a io B
clay
/B
Sc
anged om 16.2 o 15.6, di e ging by 12.5–15.2% wi h espec o he
measu ed
18.4 mg/kg
Sc con en in he clay ac ion. In iew o he es ima ions made o unknown
pa ame e s a he s a o and du ing he expe imen , his di e ence was ound o be sa is ac o y o
alida ing ou compu a ion app oach.
Soil Sys . 2018, 2, x FOR PEER REVIEW 6 o 20
2.4. Validi y o Calcula ions
The alidi y o ou compu a ion app oach was checked by compa ing budge s o one soil
componen , a key indica o o dominan soil p ocesses (<2 µm clay ac ion), and one ace elemen
(scandium, Sc), assuming hei concomi an mig a ion in loess Lu isols. This hypo hesis was based
i s on he geochemis y li e a u e om he 1960s and 1970s: (i) in e omagnesian mine als, Sc
3+
can
subs i u e o Fe
3+
and Al
3+
[29]; (ii) in sedimen a y soils, scandium is p ima ily loca ed in easily
wea he able mine als, such as ho nblende, bio i e, and chlo i e [30]; and (iii) in Lu isols o No h
Ame ica, Sc ansloca ion was shown o be closely ela ed o clay and i on ia pedogenesis p ocesses
[29]. Second, Sc is dissemina ed a li le o no a all by an h opogenic ac i i y in he en i onmen [31]
and has e y low mobili y in soils unde oxidizing and acidic en i onmen al condi ions [32]. Thi d,
ou p e ious wo k [19] e ealed ema kably high co ela ion be ween Sc and clay o he en i e soil
se o he 42-plo s expe imen (Figu e 3a, excluding manu e plo s), suppo ing he li e a u e indings.
The Sc con en in clay ac ions, analyzed on samples om plo s wi h highly con as ing
physicochemical condi ions, showed an a e age o 18.4 ± 0.37 mg/kg. Such low a iabili y o he Sc
con en o clay makes i use ul as an indica o o clay loss/accumula ion.
The s ocks o <2 µm clay ac ions and scandium we e es ablished ollowing Equa ions (1) and
(2) o he selec ed g oups o e iliza ion ea men s (c . Figu e 1) and hei geochemical budge s
we e es ablished ollowing Equa ion (3). Compa ing he co ela ion o concen a ions and budge s
o scandium and clay (Figu e 3a,b) e eals an app eciable inc ease o R
2
om 0.83 o 0.92. In bo h
g aphs, he slopes o linea eg ession we e e y close o measu ed clay Sc con en s (18.4 mg/kg),
17.6 and 17.3, espec i ely. Fo plo s displaying clea ly lowe clay con en in 2014, i.e., ≥20% since
1929, he budge a io B
clay
/B
Sc
anged om 16.2 o 15.6, di e ging by 12.5–15.2% wi h espec o he
measu ed 18.4 mg/kg Sc con en in he clay ac ion. In iew o he es ima ions made o unknown
pa ame e s a he s a o and du ing he expe imen , his di e ence was ound o be sa is ac o y o
alida ing ou compu a ion app oach.
Figu e 3. Linea co ela ion be ween clay (<2 µm ac ions) and scandium in soils o he 42-plo s
expe imen . (a) Soil concen a ions o all plo s (excep manu e plo s); (b) scandium and clay budge s
o he selec ed e ilize g oups.
2.5. Da a P esen a ion and S a is ical T ea men
Due o he ini ial se up o he expe imen , including 2 eplica es pe ea men , no s a is ics
could be ope a ed on da a om e ilized plo s; he e o e max and min ba s a e p esen ed on
his og ams o indica e in ag oup a iabili y. Fo he 8 e e ence plo s, he signi icance o di e ences
in geochemical budge s in he soil su ace ho izon be ween 1929 and 2014 was s a is ically examined
using he pai ed Wilcoxon es . A p incipal componen analysis (PCA) p ojec ion o he 2014–1929
elemen and clay budge s and he 2014 soil pH was made o help assess he impac s o soil p ocesses
on elemen dynamics.
Figu e 3.
Linea co ela ion be ween clay (<2
µ
m ac ions) and scandium in soils o he 42-plo s
expe imen . (
a
) Soil concen a ions o all plo s (excep manu e plo s); (
b
) scandium and clay budge s
o he selec ed e ilize g oups.
2.5. Da a P esen a ion and S a is ical T ea men
Due o he ini ial se up o he expe imen , including 2 eplica es pe ea men , no s a is ics could
be ope a ed on da a om e ilized plo s; he e o e max and min ba s a e p esen ed on his og ams o
Soil Sys . 2018,2, 23 7 o 20
indica e in ag oup a iabili y. Fo he 8 e e ence plo s, he signi icance o di e ences in geochemical
budge s in he soil su ace ho izon be ween 1929 and 2014 was s a is ically examined using he
pai ed Wilcoxon es . A p incipal componen analysis (PCA) p ojec ion o he 2014–1929 elemen
and clay budge s and he 2014 soil pH was made o help assess he impac s o soil p ocesses on
elemen dynamics.
3. Resul s
3.1. P esen Physicochemical Soil Cha ac e is ics
No able modi ica ions o chemical and physical soil p ope ies in he su ace ho izons we e
epo ed ea ly, as soon as 10 yea s a e he s a o expe imen a ion [
10
], and p og essi ely ampli ied
o e he yea s. The mos s iking e ec s o e ilize s a e p esen ed in Figu e 4. The ange o pH
alues in 2014 was ou s andingly wide, mo e han 5 uni s om 8.8 in CaCO
3
amended plo s o 3.5 in
he ammonium sul a e plo (Figu e 4a). The pH dec ease was highe o K-based han o Na-based
e ilize s. Al hough a ia ion o pH was ema kably as du ing he i s decades (4 uni s in 1939, [
10
]),
he magni ude o ∆pH is s ill inc easing: 4.6 uni s in 1999 [33] and 5.3 uni s in 2014 [18].
Soil Sys . 2018, 2, x FOR PEER REVIEW 7 o 20
3. Resul s
3.1. P esen Physicochemical Soil Cha ac e is ics
No able modi ica ions o chemical and physical soil p ope ies in he su ace ho izons we e
epo ed ea ly, as soon as 10 yea s a e he s a o expe imen a ion [10], and p og essi ely
ampli ied o e he yea s. The mos s iking e ec s o e ilize s a e p esen ed in Figu e 4. The ange
o pH alues in 2014 was ou s andingly wide, mo e han 5 uni s om 8.8 in CaCO3 amended plo s o
3.5 in he ammonium sul a e plo (Figu e 4a). The pH dec ease was highe o K-based han o
Na-based e ilize s. Al hough a ia ion o pH was ema kably as du ing he i s decades (4 uni s
in 1939, [10]), he magni ude o ΔpH is s ill inc easing: 4.6 uni s in 1999 [33] and 5.3 uni s in 2014 [18].
Figu e 4. Rema kable physicochemical da a in selec ed plo s o he long- e m ba e allow (LTBF)
expe imen : (a) soil pH; (b) p opo ion o exchangeable ca ions on ca ion exchange capaci y (CEC); (c)
clay con en ; (d) bulk densi y. The acid plo s include ammonium sul a e, chlo ide, and ni a e; P–
NH4: ammonium phospha e e iliza ion; e e ence L and e e ence R: mean da a o ou e e ence
plo s o he le and igh blocks, espec i ely; sodic plo s include NaNO3 and syl ini e ea men s,
po assic plo s include KCl and K2SO4 ea men s, basic plo s include CaO and CaCO3 amendmen s.
Da a modi ied a e [18].
Concomi an ly, he composi ion o he exchange complex ma kedly changed: he p opo ion o
bi alen ca ions dec eased om >98% in 1928 o ≈80% in he e e ence plo s, o 75 and 55% in he
sodic and po assic plo s, espec i ely, and o <5% in s ongly acidi ied plo s (Figu e 4b). In he la e ,
exchangeable Al occupied up o 96% o he CEC in 2014, s ongly con as ing wi h soils unde basic
amendmen s, whe e exchangeable Ca + Mg occupied almos 99% o he CEC. In he mono alen
plo s, he p opo ion o exchangeable Na + K eached 15–35% in 2014 and was highes unde K
e iliza ion. Clay con en conside ably a ied (Figu e 4c) om 134 g/kg o he NaNO3 ea men o
197 g/kg o he (NH4)2HPO4 ea men . Wi h espec o 1929, he dec ease o clay con en was mo e
ma ked o Na- han o K- e ilized plo s and indica es a p ocess o enhanced clay leaching unde
mono alen dispe si e condi ions. In he e e ence plo s, an a e age clay con en in 2014 o 174 g/kg
also poin ed o a loss o clay by leaching owa d dep h. Such widely di e ging physicochemical soil
condi ions impac ed he physical p ope ies o he su ace ho izon: e ec s o su ace sealing a e
easily isible a he su ace o he plo s a e majo ain e en s [22], as well as e ec s o soil
compac ion due o inc easing bulk densi y wi h espec o 1928, no ably in he e e ence and
mono alen plo s, eaching 1590 kg/m3 o syl ini e (Figu e 4d). By con as , bulk densi y emained
Figu e 4.
Rema kable physicochemical da a in selec ed plo s o he long- e m ba e allow (LTBF)
expe imen : (
a
) soil pH; (
b
) p opo ion o exchangeable ca ions on ca ion exchange capaci y (CEC);
(
c
) clay con en ; (
d
) bulk densi y. The acid plo s include ammonium sul a e, chlo ide, and ni a e;
P–NH
4
: ammonium phospha e e iliza ion; e e ence L and e e ence R: mean da a o ou e e ence
plo s o he le and igh blocks, espec i ely; sodic plo s include NaNO
3
and syl ini e ea men s,
po assic plo s include KCl and K
2
SO
4
ea men s, basic plo s include CaO and CaCO
3
amendmen s.
Da a modi ied a e [18].
Concomi an ly, he composi ion o he exchange complex ma kedly changed: he p opo ion o
bi alen ca ions dec eased om >98% in 1928 o
≈
80% in he e e ence plo s, o 75 and 55% in he
sodic and po assic plo s, espec i ely, and o <5% in s ongly acidi ied plo s (Figu e 4b). In he la e ,
exchangeable Al occupied up o 96% o he CEC in 2014, s ongly con as ing wi h soils unde basic
amendmen s, whe e exchangeable Ca + Mg occupied almos 99% o he CEC. In he mono alen plo s,
he p opo ion o exchangeable Na + K eached 15–35% in 2014 and was highes unde K e iliza ion.
Clay con en conside ably a ied (Figu e 4c) om 134 g/kg o he NaNO
3
ea men o 197 g/kg o
he (NH
4
)
2
HPO
4
ea men . Wi h espec o 1929, he dec ease o clay con en was mo e ma ked o
Na- han o K- e ilized plo s and indica es a p ocess o enhanced clay leaching unde mono alen
dispe si e condi ions. In he e e ence plo s, an a e age clay con en in 2014 o 174 g/kg also poin ed
Soil Sys . 2018,2, 23 8 o 20
o a loss o clay by leaching owa d dep h. Such widely di e ging physicochemical soil condi ions
impac ed he physical p ope ies o he su ace ho izon: e ec s o su ace sealing a e easily isible
a he su ace o he plo s a e majo ain e en s [
22
], as well as e ec s o soil compac ion due o
inc easing bulk densi y wi h espec o 1928, no ably in he e e ence and mono alen plo s, eaching
1590 kg/m
3
o syl ini e (Figu e 4d). By con as , bulk densi y emained unchanged o e en dec eased
unde basic amendmen s and d ied blood, and he lowes alue eached 1210 kg/m3.
3.2. Geochemical Budge s o Majo and T ace Elemen s be ween 1929 and 2014
3.2.1. Elemen Budge s in Nonamended Re e ence Plo s
Geochemical budge s in soils o he e e ence plo s p o ide in o ma ion abou cumula i e gains
and losses o elemen s unde local clima ic condi ions o e a pe iod o 85 yea s. Tables 1and 2p esen
he median alues o elemen s ocks in 1929 and 2014 in he eigh selec ed e e ence plo s, as well
as p- alues calcula ed a a 95% signi icance le el by pai ed Wilcoxon es . Signi ican di e ences
a e exp essed as bo h he elemen mass/m
2
and a ough es ima ion o mass/ha. Among he majo
elemen s, signi ican changes (p<0.01) we e obse ed o Ca, Mg, and Na (Table 1). Losses eached
1.2 kg/m2 o Ca and ≈50g/m2 o Mg, and he e was a gain o ≈100 g/m2 o Na.
Table 1.
Median alues o majo elemen s ocks calcula ed o e e ence plo s in 1929 and 2014;
signi icance o di e ences es ima ed by pai ed Wilcoxon es a p<0.05; ** signi ican a 99%.
Elemen P K Ca Mg Na Al Fe Mn
S1929 (g/m2)156 4250 2069 918 1766 11,823 5913 114
S2014 (g/m2)158 4248 876 862 1877 12,006 6091 129
p- alue 0.64 0.15 <0.01 ** <0.01 ** <0.01 ** 0.25 0.055 0.31
B2014–1929 (kg/m2)– – −1.2 −0.05 +0.1 – –
Table 2.
Median alues o ace elemen s ocks calcula ed o e e ence plo s in 1929 and 2014;
signi icance o di e ences es ima ed by pai ed Wilcoxon es a p<0.05; ** signi ican a 99%.
Elemen Cu Zn Co C Ni Mo As Cd Pb U Tl Sc
S1929 (mg/m2)6530 15,380 2062 13,312 5328 161 2583 39.5 16,753 615 129 1781
S2014 (mg/m2)6895 20,437 2492 18,374 5285 178 2539 52.0 25,856 593 128 1743
p- alue 0.31 <0.01 ** <0.01 ** <0.01 ** 0.55 <0.01 ** 0.31 <0.01 ** <0.01 ** 0.31 0.55 0.11
B2014−1929 (mg/m2)– +5057 +430 +5026 – +17 – +12.5 +9103 – – –
Fo he 12 ace elemen s (Table 2), six o hem showed signi ican gains: Cd, Co, C , Mo,
Pb, and Zn, asc ibed o a mosphe ic deposi ion be ween 1929 and 2014. The gains o Cd and
Mo anged be ween 10 and 20 mg/m
2
, bu o Co, C , Pb, and Zn, he gains we e in he o de
o 0.5–10 g/m2, and hei sum o aled abou 20 g/m2, ep esen ing an a e age yea ly deposi ion a e
o mo e han 200 mg/m2.
3.2.2. Elemen Budge s in Fe ilized Plo s
Fo plo s ecei ing chemical e ilize s and amendmen s, budge s a e p esen ed in Figu es 5and 6.
The o de o p esen a ion is based on simila pa e ns o gain/loss dis ibu ion in he e iliza ion
ea men g oups. In he g aphs, he g ay igh -angle ep esen s he 95% con idence in e al o elemen
budge s calcula ed o he e e ence plo s wi h maximum (T
+
) and minimum (T
−
) alues. In case o
signi ican inpu s o elemen s ia a mosphe ic deposi ion (Tables 1and 2), he ne elemen gains and
losses in e ilized plo s we e es ima ed wi h espec o he T+o T− alue, espec i ely.
A i s g oup o elemen s (Mn, Co, and Cd) demons a ed dis inc losses o ammonium-based
e iliza ion and d ied blood (Figu e 5a–c). Budge s o mono alen and basic ea men s we e ound
wi hin o close o he 95% con idence in e al o he e e ence plo s. In he acidi ied plo s, Mn loss
om he su ace ho izon eached
−
55 o
−
65 g/m
2
in 85 yea s (Table 3). Cobal budge s in hese
Soil Sys . 2018,2, 23 9 o 20
ea men s we e be ween abou
−
250 and
−
600 mg/m
2
(Figu e 5b). When conside ing he Co inpu by
a mosphe ic deposi ion, he ne Co budge s ep esen a loss o
−
600 o
−
800 g/m
2
(Table 3). Cadmium
budge s showed a loss o
−
30 o
−
40 mg/m
2
o he d ied blood and acid plo s, espec i ely. Howe e ,
a small gain was obse ed unde P–NH
4
e iliza ion (Figu e 5c), highligh ing he equen ly epo ed
p esence o Cd as an impu i y in phospha e e ilize s [
32
]. When conside ing a mosphe ic deposi ion
o Cd e ealed in he e e ence plo s (Table 3), he ne budge s eached
−
45, +3.5, and
−
35 mg/m
2
o he acid, N–PH
4
, and d ied blood plo s, espec i ely. I mus be no ed ha a loss o
−
39 mg/m
2
ep esen s he o al es ima ed Cd s ock p esen in he 0–25 cm su ace laye in 1929.
Soil Sys . 2018, 2, x FOR PEER REVIEW 9 o 20
deposi ion o Cd e ealed in he e e ence plo s (Table 3), he ne budge s eached −45, +3.5, and −35
mg/m
2
o he acid, N–PH
4
, and d ied blood plo s, espec i ely. I mus be no ed ha a loss o −39
mg/m
2
ep esen s he o al es ima ed Cd s ock p esen in he 0–25 cm su ace laye in 1929.
Figu e 5. Elemen budge s be ween 2014 and 1929 in he 0–25 cm laye o e ilized plo s. The colo
code is acco ding o Figu e 1. The g ay- one box ep esen s he maximum (T
+
) and minimum (T
−
)
alues o he 95 % con idence in e al o he elemen budge calcula ed in he e e ence plo s: (a)
manganese; (b) cobal ; (c) cadmium; (d) calcium; (e) magnesium; ( ) nickel; (g) aluminum; (h) i on; (i)
scandium; (j) a senic; (k) hallium; (l) clay.
A second g oup o elemen s (Ca, Mg, and Ni) displayed losses o bo h he ammonium-based
e ilize s and he mono alen plo s (Figu e 5d– ). Calcium loss was ou s andingly high, be ween
−1.4 and −1.6 kg/m
2
(i.e., −14 o −16 /ha), exceeding Ca loss in he e e ence plo s by 200 o 400 g/m
2
.
In he mono alen ea men s, he loss o Ca also sligh ly exceeded ha obse ed o he e e ence
plo s. In he basic amendmen s, he gain o Ca eached abou +2.5 kg/m
2
(i.e., +25 /ha). The
dis ibu ion o budge s o Mg and Ni showed compa able endencies. Mg loss in soils unde
Figu e 5.
Elemen budge s be ween 2014 and 1929 in he 0–25 cm laye o e ilized plo s. The colo code
is acco ding o Figu e 1. The g ay- one box ep esen s he maximum (T
+
) and minimum (T
−
) alues
o he 95% con idence in e al o he elemen budge calcula ed in he e e ence plo s: (
a
) manganese;
(
b
) cobal ; (
c
) cadmium; (
d
) calcium; (
e
) magnesium; (
) nickel; (
g
) aluminum; (
h
) i on; (
i
) scandium;
(j) a senic; (k) hallium; (l) clay.
A second g oup o elemen s (Ca, Mg, and Ni) displayed losses o bo h he ammonium-based
e ilize s and he mono alen plo s (Figu e 5d– ). Calcium loss was ou s andingly high, be ween
−
1.4 and
−
1.6 kg/m
2
(i.e.,
−
14 o
−
16 /ha), exceeding Ca loss in he e e ence plo s by 200 o 400 g/m
2
.
In he
mono alen ea men s, he loss o Ca also sligh ly exceeded ha obse ed o he e e ence plo s.
Soil Sys . 2018,2, 23 16 o 20
deposi ion (Table 2). High losses we e obse ed o Ca (Figu e 5d) in he e e ence plo s (
−
1.2 kg/m
2
)
and o acid ea men s (
−
1.6,
−
1.5,
−
1.4 kg/m
2
, espec i ely). Such magni udes b ing in o ques ion
he o igin o Ca washed ou o he su ace ho izon. Da a o exchangeable Ca in he e e ence plo s
dec eased oughly om 15 o 5 cmol/kg be ween 1929 and 2014 [
18
], ep esen ing a loss o abou
0.73 kg/m2
o Ca. In he s ongly acidi ied plo s, whe e i ually no mo e exchangeable Ca is de ec ed
a p esen , such a Ca loss accoun ed o abou 0.98 kg/m
2
. These calcula ions indica e ha , in iew
o o al Ca loss, abou 0.4–0.6 kg/m
2
mus be a ibu ed o mine al dissolu ion, likely o he mo e
wea he able plagioclase eldspa s. Magnesium also washed ou o he su ace ho izon in he e e ence
soils (Table 1) and mo e in he acid and P–NH
4
plo s (Figu e 5e). Loss o Mg was less e iden o d ied
blood, sugges ing consis en inpu ia his o ganic ni ogen sou ce.
A second indica ion o mine al wea he ing was gi en by posi i e budge da a obse ed o Al, Fe,
Sc, Tl, As, and clay in he acid, P–NH
4
, and d ied blood plo s (Figu e 5g–l, Table 4). High inpu s o
H
+
would expec edly lead o clay des uc ion and dec easing clay con en (c . Sec ion 4.1). Howe e ,
soils o he s ongly acidi ied plo s demons a ed he highes clay con en (Figu e 4c). Such appa en ly
con adic o y indings may be explained by subsidia y hyd olysis wea he ing o p ima y phyllosilica e
mine als in loess soils (mica and chlo i e) a ec ing he ine sil ac ions. Thei b eakdown would
p oduce clay-sized pa icles wi h low elec ic cha ge and hus compensa e o he acid dissolu ion
o clay
. A mechanism o clay mine alogical de elopmen o sil ac ion in acid loess soils was epo ed
by [
52
]. Such a dissolu ion p ocess o clay mine als in acid soils would explain he omnip esence o Al
on he exchange complex (Figu e 4b), and he dec easing CEC alues in e sely p opo ional wi h he
p oduced p o on loads by ammonium e ilize s epo ed by [
18
] is consis en wi h a mine alogical
mechanism o b eakdown o sil in o clay-sized mica o chlo i e pa icles. Posi i e elemen budge s o
Al, Fe, Sc, Tl, and Sc sugges hei immobiliza ion by Al oxyhyd oxides, o phospha e, in he su ace
ho izon. The inco po a ion o a pa o he unde lying E ho izon by cons an 25 cm dep h digging
in a compac ing A ho izon would lead o a ela i e accumula ion o Al, Fe, Sc, Tl, and Sc du ing he
85 yea s
o he expe imen . Fo Fe, i s ela i e accumula ion in s ongly acidic soil condi ions may
explain he di e ence be ween he obse ed posi i e Fe budge in he d ied blood plo s (+6.6 /ha)
and he heo e ical inpu s (+1.8 o +2.7 /ha) (c . Sec ion 4.1.1).
Rema kably, some elemen s, such as Mg, Ni, and Ca, we e a ec ed by bo h clay leaching and
acidi ica ion (Table 4), explaining hei in e media e posi ion be ween clay and pH in he PCA budge
p ojec ion (Figu e 8). Fu he mo e, all h ee elemen s showed posi i e budge s o he basic amendmen
plo s (Figu e 5d– ).
Alkaliniza ion
In Figu e 8, molybdenum was opposed o he soil pH, illus a ing a clea loss obse ed o he
basic plo s (
≈
400 g/ha), despi e a di use inpu o Mo o abou 170 g/ha by a mosphe ic deposi ion
(Figu e 6a). Ac ually, in neu al ae a ed soils, Mo is p esen in an anionic o m (MoO
4
)
2−
whose
mobili y inc eases in alkaline soil condi ions [
45
]. This inding demons a es a dis inc beha io o Mo
wi h espec o he o he ace elemen s s udied he e. Conside ing he inpu o Mo by a mosphe ic
deposi ion (Table 2), i s ne loss eached
−
30 mg/m
2
(Table 3). This inding is no ewo hy, as i means
ha abou 20% o he ini ial Mo s ock has been los by 85 yea s o liming p ac ices.
4.2. Signi icance o Ag onomic Expe imen s o Long-Te m Soil E olu ion S udies
Ag onomic long- e m expe imen s a e o g ea in e es o s udies aiming a un a eling he
physicochemical mechanisms o soil deg ada ion and hei consequences o declining sus ainabili y o
ecosys em quali y and se ices. In he 42-plo s ial, ou s anding a iable physicochemical and physical
p ope ies a e obse ed oday in he su ace 0–25 cm ho izon ha ela e he ascina ing s o y o almos
90 yea s o applica ion o e ilize s and amendmen s, o hei absence. The changes o soil p ope ies
ha ha e occu ed since 1928 a e due, in la ge pa , o he ca ion composi ion o he soil exchange
complex [
53
], i.e., he ac ion o compensa ing ca ions in N, P, and K e ilize s (Na
+
o H
+
) o Ca
2+
in
Soil Sys . 2018,2, 23 17 o 20
he basic amendmen s. Bi alen Ca
2+
ca ions in soils a o he loccula ion o elec onega i e colloids,
enhancing agg ega e s abili y [
15
], low bulk densi y (Figu e 2d),
and well-ae a ed
hyd odynamic
condi ions. Exchangeable Na
+
(and K
+
) is known o p omo e swelling o expendable clay mine als
and clay dispe sion [
8
]. When i exceeds 10 o 15% o he soil CEC (Figu e 2b), Na
+
may become oxic
o plan s and a o s deg ada ion o agg ega e s abili y and soil compac ion (Figu e 2d), leading o
empo a y wa e s agna ion and hyd omo phic condi ions [
51
]. High inpu o H
+
(NH
4+
-based
e ilize s) leads o s ong soil acidi ica ion and he o ma ion o hyd ogen clay [
54
]. Such H
+
clay is highly uns able and e ol es apidly in o Al-sa u a ed clay [
55
], explaining he p esence o
consis en amoun s o exchangeable Al. In he p esence o s ong complexing o ganic agen s ha
immobilize exchangeable Al, acidi ica ion leads o clay-mine al dissolu ion, as epo ed in podzol-B
ho izons [
56
,
57
]. Conside ing he low SOC con en in soils o he 42-plo s ial, s ong complexing
anions o ammonium e ilize s, such as (PO
4
)
3−
o (SO
4
)
2−
, may possibly play an Al-immobilizing ole.
P e ious wo k on he impac s o 85 yea s o e iliza ion p ac ices on pedological cha ac e is ics showed
a la ge se ies o ac i e soil p ocesses: acidi ica ion, mine al dissolu ion, aluminiza ion, neo o ma ion o
seconda y phases, e og ession o phospha es o K ia illi iza ion o smec i e, clay leaching, lixi ia ion,
o empo a y wa e logging [
18
]. In eal ield si ua ions, s udy si es ha o e such a wide panel o
p ocesses and physicochemical condi ions uni ed in a es ic ed a ea wi h ini ially iden ical soils a e
excep ional, i no nonexis en . Ac ually, due o con inuous expe imen al cons ain s, he 42-plo s
expe imen ac s as a pedo on in eal clima ic condi ions. Toge he wi h i s his o ical soil a chi e,
such a long- e m ba e allow expe imen enables access o synch onic and diach onic aspec s o soil
e olu ion on a cen ennial ime scale.
5. Conclusions
In his wo k, he soils o he 42-plo s LTBF ell ascina ing s o ies abou his o ical dynamics o
majo and ace elemen s and cons ain by con inuous applica ion o e ilize s and amendmen s,
o by
hei absence. Taking accoun o modi ied physical p ope ies in he 0–25 cm su ace ho izon du ing
he expe imen , s ocks o elemen s we e calcula ed o 1929 and 2014 and budge s we e es ablished.
The ele ance o ou compu a ional app oach was checked by he equi alen losses o scandium and
clay in Na-based e ilized plo s, unde he hypo hesis o a p edominan loca ion o Sc in phyllosilica e
mine als in loess soil. The budge s demons a ed clea gains o elemen s by e ilize inpu s (no ably
P, K, Ca, Na, Cd, and U) o a mosphe ic deposi ion in he e e ence plo s (Na, Cd, Co, C , Mo, Pb,
and Zn
). Addi ionally, he budge s ga e insigh in o a se ies o di e ging elemen losses con olled by
di e en soil p ocesses ha we e induced by changing physicochemical soil condi ions o e 85 yea s,
which can be conside ed as a long- e m ime span in ag onomic expe imen a ion s udies, bu a he a
sho - e m ime span in soil de elopmen .
Clay leaching was s ongly a o ed in Na- and K-based e ilize s and coincided wi h consis en
losses o Al, Fe, Mg, Sc, Ni, C , Tl, and As. In he acidi ied soils unde ammonium-based e iliza ion,
la ge losses we e obse ed o Ca, Mg, Mn, Co, and Ni, whe eas unde basic amendmen s wi h high
soil pH, a clea loss o Mo was demons a ed. Howe e , elemen s we e some imes a ec ed by bo h
inpu s and losses, i.e., Cd inpu s by phospha e e ilize s and a mosphe ic deposi ion and i s lixi ia ion
in acid soil condi ions, bu o en he geochemical budge s p o ided insigh in o he main p ocesses.
Calcula ion o dec easing con en s o o al and exchangeable Ca ga e e idence o enhanced mine al
wea he ing in he acid and e e ence plo s, p obably o eldspa s, whe eas ela i e accumula ions o
Al, Fe, Sc, and Tl (and As) in he acid plo s poin ed o mine al wea he ing o phyllosilica e.
P esen ly, he 42-plo s LTBF expe imen shows a ema kable wide di e si y o elemen dynamics
in eac ion o e iliza ion ea men s. Howe e , despi e a s ic and unchanged expe imen al plan,
clea eac ions we e no ound o all elemen s. Fo some elemen s, inpu s may coun e balance losses.
Fo elemen s such as Zn and Pb, he magni ude o inpu s ia a mosphe ic deposi ion masks hei
a e unde he cons ain o di e ging physicochemical condi ions. Mo e comp ehensi e insigh on
Soil Sys . 2018,2, 23 18 o 20
elemen dynamics may be ob ained om de ailed s udy o samples om he his o ical soil a chi e,
gi ing access o he ch onology o geochemical changes o he soil su ace.
Acknowledgmen s:
The au ho s g ea ly acknowledge all people who we e, since 1928, o a e s ill oday in cha ge
o he main enance and echnical exploi a ion o he 42-plo s expe imen : applica ion o e ilize s, soil digging,
sample collec ion and p epa a ion, emo al o weeds, e c. Thei conscien ious e o s ha e made i possible o
de elop ou geochemical budge app oach and es i s alidi y. Financial suppo came om INRA and om he
Agence de l’En i onnemen e de la Maî ise de l’Ene gie ADEME. R. Pa adelo hanks he Spanish Minis y o
Economy and Compe i i eness (MINECO) o a Ramón y Cajal ellowship (RYC-2016-19286). We hank Sébas ien
B euil o sample p epa a ion and Ch is ian Lelay o hin sec ion p epa a ion. We a e g a e ul o wo anonymous
e iewe s o hei posi i e eac ions o ou wo k and help ul sugges ions.
Au ho Con ibu ions:
Folke an Oo concei ed and designed he s udy; Folke an Oo , Remigio Pa adelo,
Ghislaine Dela ue, Nicolas P oix, Denis Baize and Fab ice Monna analyzed he expe imen al da a;
Nicolas P oix
supe ised he chemical analyses; Folke an Oo w o e he pape wi h he help o Remigio Pa adelo,
Ghislaine Dela ue, Nicolas P oix, Denis Baize and Fab ice Monna.
Con lic s o In e es : The au ho s decla e no con lic o in e es .
Re e ences
1. Lal, R. Res o ing Soil Quali y o Mi iga e Soil Deg ada ion. Sus ainabili y 2015,7, 5875–5895. [C ossRe ]
2.
Pa adelo, R.; an Oo , F.; Chenu, C. Wa e -dispe sible clay in ba e allow soils a e 80 yea s o con inuous
e ilize s addi ion. Geode ma 2013,200–201, 40–44. [C ossRe ]
3.
Manlay, R.; Felle , C.; Swi , M. His o ical e olu ion o soil o ganic ma e concep s and hei ela ionships
wi h he e ili y and sus ainabili y o c opping sys ems. Ag ic. Ecosys . En i on.
2007
,119, 217–233.
[C ossRe ]
4.
Rajan, K.; Na a ajan, A.; Kuma , K.; Bad ina h, M.; Gowda, R. Soil o ganic ca bon—The mos eliable
indica o o moni o ing land deg ada ion by soil e osion. Cu . Sci. 2010,99, 823–827.
5.
Ree es, D.W. The ole o soil o ganic ma e in main aining soil quali y in con inuous c opping sys ems.
Soil Tillage Res. 1997,43, 131–167. [C ossRe ]
6.
Balesden , J.; Wagne , G.H.; Ma io i, A. Soil o ganic ma e u no e in long- e m ield expe imen s as
e ealed by C-13 na u al abundance. Soil Sci. Soc. Am. J. 1988,52, 118–124. [C ossRe ]
7.
Dixon, J.B.; Weed, S.B. Mine als in Soil En i onmen s, 2nd ed.; SSSA Book Se ies 1; Soil Scien i ic Socie y
Ame ican: Madison, WI, USA, 1989; ISBN 0-89118-787-1.
8.
Tessie , D. Beha iou and mic os uc u e o clay mine als. Soil Colloids and Thei Associa ions in Agg ega es;
De Bood , M.F., Hayes, M.H.B., He billon, A., Eds.; Na o ASI Se ies B: Physics; Plenum P ess: New Yo k, NY,
USA, 1990; Volume 215, pp. 387–415. ISBN 0-306-43419-9.
9.
Van Oo , F.; Thi y, M.; Foy, E.; Fujisaki, K.; Dela ue, G.; Dai on, R.; Jongmans, A.G. Impac s o one cen u y
o was ewa e discha ge on soil ans o ma ion h ough e olysis and ela ed me al pollu an dis ibu ions.
Sci. To al En i on. 2017,590–591, 1–13. [C ossRe ] [PubMed]
10.
Bu ge in, H.; Hénin, S. Dix années d’expé iences su l’ac ion des eng ais su la composi ion e les p op ié és
d’un sol de limon. Ann. Ag on. 1939,9, 771–799.
11.
Ba é, P.; Eglin, T.; Ch is ensen, B.T.; Ciais, P.; Houo , S.; Kä e e , T.; an Oo , F.; Peylin, P.; Poul on, P.R.;
Romanenko , V.; e al. Quan i ying and isola ing s able ca bon using long- e m ba e allow expe imen s.
Biogeosciences 2010,7, 3839–3850. [C ossRe ]
12.
Semlali, R.; Dessogne, J.; Monna, F.; Bol e, J.; Azimi, S.; Denaix, L.; Loube , M.; an Oo , F. Modeling lead
inpu and ou pu in soils by using lead iso opic geochemis y. En i on. Sci. Technol.
2004
,38, 1513–1521.
[C ossRe ] [PubMed]
13.
Monna, F.; an Oo , F.; Hube , P.; Dominik, J.; Bol e, J.; Loizeau, J.L.; Labanowski, J.; Lam i, J.; Pe i , C.;
Le Roux, G.; e al. Modelling o 137Cs mig a ion in soils using an 80-yea s soil a chi e. Role o e ilize s
and ag icul u al amendmen s. J. En i on. Radioac . 2009,100, 9–16. [C ossRe ] [PubMed]
14.
Ba é, P.; Plan e, A.F.; Cécillon, L.; Lu alla, S.; Baudin, F.; Be na d, S.; Ch is ensen, B.T.; Fe nandez, J.M.;
Houo , S.; Kä e e , T.; e al. The ene ge ic and chemical signa u es o pe sis en soil o ganic ma e .
Biogeochemis y 2016,1–2, 1–12. [C ossRe ]
Soil Sys . 2018,2, 23 19 o 20
15.
Pa adelo, R.; an Oo , F.; Ba é, P.; Billiou, D.; Chenu, C. Soil o ganic ma e s abiliza ion a he plu i-decadal
scale: Insigh om ba e allow soils wi h con as ing physicochemical p ope ies and mac os uc u es.
Geode ma 2016,275, 48–54. [C ossRe ]
16.
Haney, R.J. A e Fe ilize s Punishing Ou Soils? Yale School o Fo es y & En i onmen al S udies: New Ha en,
CT, USA, 2017; A ailable online: h p://e360.yale.edu/ ea u es/why-i s- ime- o-s op-punishing-ou -soils-
wi h- e ilize s-and-chemicals/ (accessed on 5 Decembe 2017).
17.
IUSS Wo king G oup WRB. Wo ld Re e ence Base o Soil Resou ces 2014, Upda e 2015. In e na ional soil
Classi ica ion Sys em o Naming Soils and C ea ing Legends o Soil Maps; Wo ld Soil Resou ces Repo s No. 106;
FAO: Rome, I aly, 2014; ISBN 978-92-5-108369-7.
18.
Van Oo , F.; P oix, N.; Pa adelo, R.; Dela ue, G.; B euil, S.; Baize, D.; Richa d, A. De niè es nou elles de
42 ieilles
pa celles. Indica eu s d’é olu ions pédologiques in a-cen enai es en Néolu isol de lœss nu, sous
con ain e d’applica ions con inues de ma iè es e ilisan es. É ude e Ges ion des Sols 2016,23, 143–162.
19.
Van Oo , F.; Pa adelo, R.; P oix, N.; B euil, S.; Dela ue, G.; T ou é, A.; Baize, D.; Monna, F.; Richa d, A.
A senic e Vieilles Pa celles. É a s e bilans géochimiques dans un Néolu isol de lœss nu, a ec ou sans
appo s de ma iè es e ilisan es depuis 1928. É ude e Ges ion des Sols 2017,24, 99–126.
20.
AFNOR. Mé hodes D’analyse Chimique. In E alua ion de la Quali édes Sols;
Recueil No mes & Réglemen a ion
;
AFNOR: Pa is, F ance, 2004; Volume 1, pp. 401–409, ISBN 2.12.213151-9.
21.
Baize, D. Teneu s To ales en Elémen s T aces Mé alliques Dans les Sols (F ance); INRA: Pa is, F ance, 1997;
ISBN 2-7380-0747-3.
22.
B esson, L.M.; Boi in, J. Mo phological cha ac e iza ion o soil c us de elopmen s ages on an expe imen al
ield. Geode ma 1990,47, 301–325. [C ossRe ]
23.
Pe nes-Debuyse , A.; Tessie , D. Soil physical p ope ies a ec ed by long- e m e iliza ion. Eu . J. Soil Sci.
2004,55, 505–512. [C ossRe ]
24.
Do an, J.W.; Sa an onio, M.; Liebig, M.A. Soil heal h and sus ainabili y. Ad . Ag on.
1996
,56, 1–54.
[C ossRe ]
25.
Elle , B.H.; Be any, J.R. Calcula ion o o ganic ma e and nu ien s s o ed in soils unde con as ing
managemen egimes. Can. J. Soil Sci. 1995,75, 529–538. [C ossRe ]
26.
Balabane, M.; Fai e, D.; an Oo , F.; Dahmani-Mulle , H. Mu ual e ec s o soil o ganic ma e dynamics
end hea y me als a e in a me allophy e g assland. En i on. Pollu . 1999,105, 45–54. [C ossRe ]
27.
Isambe , M. E udes des Sols des Pa celles Expé imen ales du CNRA Ve sailles, Pa celles des Closeaux; In e nal
Repo ; SESCPF: O léans, F ance, 1979.
28.
Monni, C. S abilisa ion Physique e Physico-Chimique de la Ma iè e O ganique dans les Ho izons P o onds
du Sol. Ph.D. Thesis, Uni e si éPie e e Ma ie Cu ie, Pa is, F ance, 2008.
29.
Ho o i z, C.T.; Gschneidne , K.A., J .; Melson, G.A.; Youngblood, D.H.; Schock, H.H. Scandium. I s
Occu ence, Chemis y, Physics, Me allu gy, Biology and Technology; Academic P ess: London, UK, 1975;
ISBN 978-0124125353.
30.
Mi chel, R.L. T ace Elemen s in Soils. Chemis y o he Soil, 2nd ed.; Bea , F.E., Ed.; Rheinhol : New Yo k, NY,
USA, 1964.
31.
Sho yk, W.; Weiss, D.; K ame s, J.; F ei, R.; Che bukin, A.K.; Gloo , M.; Reese, S. Geochemis y o he pea
bog a É ang de la G uè e, Ju a Moun ains, Swi ze land, and i s eco d o a mosphe ic Pb and li hogenic
ace me als (Sc, Ti, Y, Z , and REE) since 12 370
14
C y BP. Geochem. Cosmochim. Ac a
2001
,65, 2337–2360.
[C ossRe ]
32.
Kaba a Pendias, A. T ace Elemen s in Soils and Plan s, 4 h ed.; CRC P ess: Boca Ra on, FL, USA, 2010;
ISBN 978-1-4200-9368-1.
33.
Pe nes-Debuyse , A.; Tessie , D. In luence de ma iè es e ilisan es su les p op ié és des sols : Cas des
42 pa celles de L’INRA àVe sailles. É ude e Ges ion des Sols 2002,9, 177–186.
34.
S oops, G.; Ma cellino, V.; Mees, F. In e p e a ion o Mic omo phological Fea u es o Soils and Regoli hs; Else ie :
Ams e dam, The Ne he lands, 2010; 720p, ISBN 978-0-444-53156-8.
35.
Yun a, F.; Di Foggia, M.; Bellido-Díaz, V.; Mo ales-Calde ón, M.; Tessa in, P.; López-Rayo, S.; Tin i, A.;
Ko ács, K.; Klencsá , Z.; Fodo , F.; e al. Blood meal-based compound. Good choice as i on e ilize o
o ganic a ming. J. Ag ic. Food Chem. 2013,61, 3995–4003. [C ossRe ] [PubMed]
Soil Sys . 2018,2, 23 20 o 20
36.
Alloway, B.J. Hea y Me als in Soils, 3 d ed.; Sp inge : Do d ech , The Ne he lands, 2013; ISBN 9789400744691.
37.
Jus e, C.; Tauzin, J. E olu ion du con enu en mé aux lou ds d’un sol de limon main enu en jachè e nue ap ès
56 années d’applica ion con inue de di e s eng ais e amendemen s. CR Acad. Ag ic. 1986,72, 739–746.
38.
Ma, Y.; Hooda, P.S. Ch omium, Nickel and Cobal . In T ace Elemen s in Soils; Hooda, P.S., Ed.; Whiley:
Chiches e , UK, 2010; pp. 461–479. ISBN 978-1-405-16037-7.
39.
Van Leeuwen, E.P.; D aaije , G.P.J.; E isman, J.W. Mapping we deposi ion o acidi ying componen s and
base ca ions o e Eu ope using measu emen s. A mos. En i on. 1996,30, 2495–2511. [C ossRe ]
40.
Belon, E.; Boisson, M.; Depo es, I.Z.; Eglin, T.K.; Feix, I.; Bispo, A.O.; Galsomies, L.; Leblond, S.; Guellie , C.R.
An in en o y o ace elemen s inpu s o F ench ag icul u al soils. Sci. To al En i on.
2012
,439, 87–95.
[C ossRe ] [PubMed]
41.
Saby, N.; A ouays, D.; Boulonne, L.; Joli e , C.; Pocho , A. Geos a is ical assessmen o Pb in soil a ound
Pa is, F ance. Sci. To al En i on. 2006,367, 212–221. [C ossRe ] [PubMed]
42.
Rampazzo, G.; Innocen e, E.; peco a i, E.; Squizza o, S.; Valo o, G. Po en ial ha m ul elemen s in he
a mosphe e. In PHE’s, En i onmen and Human Heal h; Bini, C., Bech, J., Eds.; Sp inge : Do d ech ,
The Ne he lands, 2014; pp. 1–36. ISBN 978-94-017-8964-6.
43.
G anie , L.; Che euil, M.; Ca u, A.M.; Ches e iko , A. A mosphe ic allou o o ganochlo ines and hea y
me als on he Pa is a ea (F ance). Sci. To al En i on. 1992,126, 165–172. [C ossRe ]
44.
Azimi, S.; Ludwig, A.; Thé eno , D.R.; Colin, J.L. T ace me al de e mina ion in o al a mosphe ic deposi ion
in u al and u ban a eas. Sci. To al En i on. 2003,308, 247–256. [C ossRe ]
45.
E ans, L.J.; Ba abash, S.J. Molybdenum, Sil e , Thallium and Vanadium. In T ace Elemen s in Soils;
Hooda, P.S., Ed.; Whiley: Chiches e , UK, 2010; pp. 515–549. ISBN 978-1-405-16037-7.
46.
T emel, A.; Masson, P.; S e ckeman, T.; Baize, D.; Mench, M. Thallium in F ench ag osys ems. I. Thallium
con en s in a able soils. En i on. Pollu . 1997,95, 293–302. [C ossRe ]
47.
Punshon, T.; Jackson, B.P.; Meha g, A.A.; Wa czak, T.; Scheckel, K.; Gue ino , M.L. Unde s anding a senic
dynamics in ag onomic sys ems o p edic and p e en up ake by c op plan s. Sci. To al En i on.
2017
,
581–582, 209–220. [C ossRe ] [PubMed]
48.
Manning, B.A.; Goldbe g, S. Adso p ion and s abili y o a senic(III) a he clay mine al-wa e in e ace.
En i on. Sci. Technol. 1997,31, 2005–2011. [C ossRe ]
49.
Pa y, J.P.; P obs , A.; Damb ine, E.; Thomas, A.L. C i ical loads o acidi y o F ance: Sensi i i y a eas in he
no h-eas e n F ance. Wa e Soil Ai Pollu . 1995,85, 2407–2412. [C ossRe ]
50.
UNEP. Global En i onmen Ou look; GEO4; Uni ed Na ions En i onmen P og amme: Vale a, Mal a, 2007;
ISBN 978-92-807-2836-1.
51.
Van B eemen, N.; Buu man, P. Soil Fo ma ion; Sp inge : Do d ech , The Ne he lands, 2013; ISBN 978-1-4020-0718-7.
52.
Ha dy, M.; Jamagne, M.; Elsass, F.; Robe , M.; Chesneau, D. Mine alogical de elopmen o he sil ac ions
o a Podzolu isol on lœss in he Pa isBasin (F ance). Eu . J. Soil Sci. 1999,50, 443–456. [C ossRe ]
53.
Bohn, H.L.; McNeal, B.L.; O’Conno , G.A. Soil Chemis y, 4 h ed.; John Wiley & Sons: New Yo k, NY, USA,
2015; ISBN 978-1118629253.
54.
Bol , G.H.; B uggenwe , M.G.M. Soil Chemis y. A. Basic Elemen s; Else ie : Ams e dam, The Ne he lands, 1978.
55.
Eeckman, J.P.; Laudelou , H. Chemical s abili y o hyd ogen-mon mo illoni e suspensions. Colloid Polym. Sci.
1961,178, 99–107. [C ossRe ]
56.
Robe , M.; Razzaghe, M.H.; Range , J. Rôle du ac eu biochimique dans la podzolisa ion. In Podzols e
Podzolisa ion; Righi, D., Chau el, A., Eds.; AFES-INRA: Pa is, F ance, 1987; pp. 207–223.
57.
Robe , M.; Razzaghe, M.H.; Vicen e, M.A.; Veneau, G. Rôle du ac eu biochimique dans l’al é a ion des
miné aux silica és. Science du Sol 1979,2–3, 153–174.
©
2018 by he au ho s. Licensee MDPI, Basel, Swi ze land. This a icle is an open access
a icle dis ibu ed unde he e ms and condi ions o he C ea i e Commons A ibu ion
(CC BY) license (h p://c ea i ecommons.o g/licenses/by/4.0/).
