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The legacy o deep ploughing and liming : A 1990s expe imen al si e e isi ed
© 2024 The Au ho s. Published by Else ie B.V.
Published e sion
Hy äluoma, Ja i; Keskinen, Riikka; He manenko, Vik o iia; Kinnunen, Sami;
Mie inen, A u; Niemi, Pe i; Kase a, Janne; Soinne, Helena
Hy äluoma, J., Keskinen, R., He manenko, V., Kinnunen, S., Mie inen, A., Niemi, P., Kase a, J., &
Soinne, H. (2025). The legacy o deep ploughing and liming : A 1990s expe imen al si e e isi ed.
Soil and Tillage Resea ch, 245, A icle 106323. h ps://doi.o g/10.1016/j.s ill.2024.106323
2025
The legacy o deep ploughing and liming – A 1990s expe imen al
si e e isi ed
Ja i Hy ¨
aluoma
a,*
, Riikka Keskinen
a
, Vik o iia He manenko
b
, Sami Kinnunen
c
,
A u Mie inen
c
, Pe i Niemi
d
, Janne Kase a
a
, Helena Soinne
b
a
Na u al Resou ces Ins i u e Finland (Luke), Jokioinen, Finland
b
Na u al Resou ces Ins i u e Finland (Luke), Helsinki, Finland
c
Depa men o Physics, Nanoscience Cen e , and School o Resou ce Wisdom, Uni e si y o Jy ¨
askyl¨
a, Jy ¨
askyl¨
a, Finland
d
H¨
ame Uni e si y o Applied Sciences (HAMK), Fo ssa, Finland
ARTICLE INFO
Keywo ds:
Tillage
S a i ica ion
Ca bon s o age
Po e sys em
Yield
ABSTRACT
Managemen o ag icul u al soils o inc eased p oduc i i y may exe posi i e o nega i e e ec s on soil
s uc u e, unc ions, and o ganic ca bon (SOC) s ocks. In his s udy, a ield expe imen es ablished in 1993 on a
clayey soil in sou hwes Finland was e isi ed o in es iga e he long- e m e ec s o deep ploughing and liming
on SOC concen a ion and s ock, pa icula e (POC) and mine al-associa ed (MOC) ac ions o SOC, pH, elec ical
conduc i i y (EC), bulk densi y (BD), po osi y, c i ical po e size and ce eal yield. The expe imen comp ised
whole plo s o con en ional illage (CT) o a maximum dep h o ca. 20 cm, and plo s deep ploughed o ca. 35 cm
dep h by a comme cial (DP1) o by a sel -made (DP2) plough. The illage plo s we e di ided in o h ee spli -plo s
assigned o liming ea men s (low, medium and high). Th ee decades a e implemen a ion, he inc easing
liming a es s ill induced consis en di e ences in soil pH, a signi ican inc easing e ec on o al po osi y in he
subsoil, and a ma ginally signi ican dec ease in yield wi h an inc ease in soil acidi y. The deep ploughing
exe ed a mino di e ence in opsoil ex u e, sligh ly lowe ed SOC concen a ion in he opsoil in DP2 in
compa ison o CT, and sligh ly highe subsoil SOC concen a ion in DP1 in compa ison o CT, which indica ed
ans e o he opsoil SOC o deepe laye s and dilu ion o he SOC in he new opsoil. Howe e , no signi ican
di e ences be ween he illage ea men s occu ed in SOC s ocks. In MOC and POC concen a ions, he e we e
no signi ican di e ences be ween he con ol and illage ea men s. The e ec s o deep ploughing on soil
s uc u al p ope ies on he decadal ime scale we e mino and sca e ed. Ce eal yield exhibi ed a sligh nega i e
end o deep ploughing. Fo EC and BD, no ea men e ec s we e eco ded. O e all, he s udy showed ha he
legacy o soil managemen e ec s on soil p ope ies can be pe sis en on decadal ime scales, bu no pe manen
s uc u al damage due o deep ploughing no gains in SOC s ock acc ual could be obse ed.
1. In oduc ion
C oplands a e in ensi ely managed o inc ease biomass p oduc ion,
which o en in ol es ade-o s in sus ainabili y and en i onmen al
impac s (DeF ies e al., 2004; Vanwalleghem e al., 2017). In soil illage,
educed shallow ea men and di ec d illing minimizing soil dis u -
bance ha e been long used o a oiding loss o soil by e osion and
deg ada ion o soil o ganic ma e (SOM) (Cannell and Hawes, 1994).
Howe e , con en ional ploughing, in which he soil is in e ed, s ill
se es in con olling pe ennial weeds, inco po a ing c op esidues and
soil amendmen s, and loosening compac ed soil (Guul-Simonsen e al.,
2002). Compac ed soil laye s educing pe meabili y o ai , wa e and
oo s a di e en dep hs can o m h ough na u al p ocesses o be caused
by comp ession om wheels o he ield machine y o o ampling
animals (Ba ey, 2009). A ploughing dep h o 20 cm o somewha less is
gene ally conside ed su icien , bu deepe loosening allowing deepe
inco po a ion o o ganic ma e ial and deepe oo de elopmen is also
possible (Guul-Simonsen e al., 2002).
Se e al o ms o deep illage, i.e., mechanical modi ica ion o he soil
p o ile below he ypical illage dep h, ha e been de eloped (Schneide
e al., 2017). In subsoiling o deep ipping, he soil s uc u e is loosened
wi h he aim o dec easing he bulk densi y and soil s eng h in he
* Co esponding au ho .
E-mail add ess: [email p o ec ed] (J. Hy ¨
aluoma).
Con en s lis s a ailable a ScienceDi ec
Soil & Tillage Resea ch
jou nal homepage: www.else ie .com/loca e/s ill
h ps://doi.o g/10.1016/j.s ill.2024.106323
Recei ed 13 May 2024; Recei ed in e ised o m 2 Oc obe 2024; Accep ed 3 Oc obe 2024
Soil & Tillage Resea ch 245 (2025) 106323
A ailable online 7 Oc obe 2024
0167-1987/© 2024 The Au ho s. Published by Else ie B.V. This is an open access a icle unde he CC BY license (
h p://c ea i ecommons.o g/licenses/by/4.0/ ).
subsoil laye wi hou in e ing he soil ho izons. Deep ploughing, in
u n, leads o he in e sion o he soil p o ile, whe eby subsoil is b ough
up o he su ace and he opsoil laye is bu ied deepe . In p ac ice, a e
he deep ploughing ope a ion he soil p o ile ypically consis s o in-
clined u ow slices, and a e ollowing illage ope a ions, a new opsoil
laye mixing he old subsoil and opsoil is o med, while pa o he old
opsoil ich in SOM is le unde he new illage laye (Alcan a a e al.,
2016). Deep ploughing is mos ly pe o med only once, and he common
objec i e o he ope a ion has been o loosen he compac ed soil laye s
ha limi oo g ow h and wa e in il a ion and hus acili a e access o
nu ien and wa e esou ces s o ed in he subsoil (Baumha d e al.,
2008).
In ecen yea s, he e has been in e es in how deep illage impac s
soil o ganic ca bon (SOC) s ocks in soils (Feng e al., 2020). While
educed o ze o illage is equen ly p esen ed as a SOC seques a ion
measu e (Me an e e al., 2017 and e e ences he ein), hese p ac ices
lead o he en ichmen o SOC in he soil su ace bu limi he inpu o
c op esidues deepe in o he soil. Consequen ly, se e al s udies ha e
epo ed no inc ease in he SOC s ocks o he whole soil p o ile (Singh
e al., 2015; Ogle e al., 2019; Honkanen e al., 2021). The concep o
SOC sa u a ion, which is s ill a opic o ac i e deba e (e.g., Begill e al.,
2023; Co u o e al., 2023; Poeplau e al., 2023; Six e al., 2024) is based
on he idea ha soil mine al ac ion has a ini e capaci y o p o ec C in
soils (S ewa e al., 2007, 2008). Thus, a e SOC sa u a ion is eached,
no addi ional eac i e mine al-associa ed si es a e a ailable o physi-
cochemical s abiliza ion o SOC, whe eby ine- ex u ed soils wi h high
speci ic su ace a ea ha e a highe SOC sa u a ion limi han soils
o med o coa se pa icles (Hassink, 1997; Hassink and Whi mo e, 1997;
Dex e e al., 2008). The sa u a ion concep also indica es ha soils close
o sa u a ion ha e lowe C seques a ion e iciency han hose wi h
clea ly lowe SOC con en (Six e al., 2002). The sa u a ion concep hus
sugges s ha subsoils low in SOC could p o ide a mo e e icien a ge
o C seques a ion measu es han opsoils, al hough mos measu es
aiming o seques e SOC ocus on he opsoil laye . In addi ion, many
adioca bon s udies wi h 14 C iso ope ha e shown ha C age inc eases
wi h inc easing soil dep h (Gleixne , 2013; Balesden e al., 2018; Shi
e al., 2020), which indica es highe s abili y o C in he subsoil. F om
he SOC seques a ion pe spec i e, deep ploughing bu ies he SOC- ich
opsoil in o deepe laye s whe e decomposi ion a es a e lowe
(Alcan a a e al., 2017; Wo dell-Die ich e al., 2017). Concu en ly,
a e deep ploughing he SOC con en o newly o med opsoil is
dec eased and ca ied a he away om sa u a ion, which inc eases he
SOC acc ual po en ial o he opsoil o ‘con en ional’ SOC seques a ion
measu es, such as high esidue c ops, co e c ops, and no- ill.
Some esul s indica ing ema kable inc eases in SOC s ocks a e
deep ploughing ha e been epo ed. Fo example, Alcan a a e al. (2016)
conside ed se e al si es in Ge many, which had been deep ploughed
35–50 yea s ea lie and epo ed ha deep ploughing esul ed on
a e age in 42 % highe SOC s ocks. Schiedung e al. (2019), in u n,
in es iga ed deep lipping si es in New Zealand, whe e he soil p o ile
had been in e ed by exca a o s and epo ed an a e age inc ease o
69 % in SOC s ocks 20 yea s a e he deep lipping. Some s udies ha e
indica ed a much mo e limi ed e ec o deep ploughing (Feng e al.,
2020; Bu on e al., 2022). Rega ding he SOC acc ual, he bene i s o
deep ploughing emain unclea as he e ec i eness o deep ploughing
has been ound o be highly dependen on si e-speci ic soil and en i-
onmen al condi ions (Feng e al., 2020).
While he e is e idence ha deep ploughing may unde ce ain
condi ions ha e posi i e e ec s in e ms o SOC acc ual, he e ha e been
conce ns ha such a se e e illage ope a ion may ha e nega i e in-
luences on soil s uc u e and unc ions (Ba eye e al., 2020). SOC
con en is an impo an con ol o soil agg ega e s abili y (Soinne e al.,
2016), whe eby SOC dilu ion esul ing om deep ploughing may lead o
weakened opsoil s uc u e and inc eased isk o soil e osion. Weak-
ened agg ega e s abili y may also a ec he SOC dynamics h ough he
educed physical p o ec ion o o ganic ma e (Dungai e al., 2012;
K a chenko e al., 2015). Schneide e al. (2017) e iewed s udies whe e
he yield e ec s o deep illage had been in es iga ed and hei
me a-analysis showed on a e age a sligh (+6 %) yield inc ease. How-
e e , hey concluded ha he yield e ec s o deep illage a e inconsis en
and highly si e-speci ic as 40 % o he e iewed s udies had esul ed in
dec eased yield.
In addi ion o illage ope a ions, ex e nal nu ien and lime inpu s
a e managemen p ac ices ha exe an e ec on soil p ope ies
(Fage ia, 2002). Lime is applied o adjus he pH o acidic soils o he
op imal ange o plan g ow h and o main ain i by coun e balancing
acidi ica ion caused by acidi ying (ammonium-based) e ilize s and
acidic p ecipi a ion and deposi ion (Goulding, 2016). In addi ion o pH
inc ease-induced in luence on he bioa ailabili y o elemen s, liming
may exhibi posi i e e ec s on soil s uc u e, such as inc eased agg e-
ga e s abili y and dec eased dispe sion, ia changes in ca ion composi-
ion and inc eased ionic s eng h o he soil solu ion (Holland e al.,
2018). The ne e ec o liming on SOC s ocks shows a iabili y due o
con a y e ec s (Pa adelo e al., 2015). On one hand, liming can in-
c ease SOC mine aliza ion h ough enhanced biological ac i i y and on
he o he hand inc ease C inpu o soil h ough imp o ed plan
p oduc i i y.
P e ious esea ch shows ha he e ec s o deep ploughing on C
seques a ion a e inconsis en and u he in es iga ions in di e en
en i onmen s a e needed o unde s and he si e-speci ic in luences o
deep ploughing. In addi ion, i would be impo an o un a el he
s uc u al e ec s o deep ploughing o a oid o e simpli ied solu ions o
SOC acc ual which o ge he possible nega i e e ec s o deep ploughing
on soil unc ioning. To his end, we e isi ed an old expe imen loca ed
in sou hwes Finland and in es iga ed he long- e m e ec s o deep
ploughing and liming on SOC s ocks as well as soil s uc u e 29 yea s
a e he ea men s. The s udied si e has high clay con en and manu e
has been equen ly used in e iliza ion a e he ac i e expe imen al
pe iod. The e o e, ou s udy also p o ides in o ma ion on how SOC-
deple ed opsoil eco e ed a e deep ploughing when he soil has
plen y o mine al su aces a ailable o SOC s abiliza ion due o ine
ex u e and he e is an addi ional ex e nal C inpu due o manu e
applica ion. In addi ion, we s udied he soil s uc u e bo h in opsoil and
subsoil o assess whe he s uc u al di e ences can be obse ed h ee
decades a e deep ploughing. Ou s udy hus conside ed he pe sis ence
o soil managemen p ac ices on he decadal ime scale o bo eal clay
soil and aimed a answe ing he ollowing p ima y esea ch ques ions:
(1) Does deep ploughing posi i ely a ec C s ocks? (2) Does deep
ploughing lead o nega i e soil s uc u e and/o yield e ec s? (3) Does
liming induce long- e m di e ences in soil pH and c op yield?
2. Ma e ial and me hods
2.1. Field expe imen
The expe imen exploi ed in he cu en s udy was o iginally es ab-
lished in Augus 1993 on a clay soil in Jokioinen, sou h-wes e n Finland
(60.858◦N, 23.433◦E), o explo e possibili ies o imp o ing he a ail-
abili y o phospho us (P) du ing d ough pe iods by deep soil inco po-
a ion (Saa ela e al., 2000). A spli -plo design was applied such ha
h ee illage ea men s each in h ee eplica es we e assigned o whole
plo s o 14 m ×63 m in size. These whole plo s we e di ided in o h ee
spli -plo s assigned o liming ea men s aiming a pH le els o 6.1 (LL),
6.5 (ML) and 7.0 (HL). The soil pH be o e he ea men s was 6.1 and he
amoun o lime added o each he ele a ed pH le el o ML and HL
ea men s anged be ween 12 and 36 ha
−1
depending on he aimed
le el and plough dep h (Saa ela e al., 2000). The spli -plo s we e u he
di ided in o ou spli -spli -plo s o di e en P e iliza ion a es, which
we e la e spli once mo e o in es iga ing e ilize applica ion
me hods. These P e iliza ion spli -spli -plo s we e no conside ed in he
p esen s udy.
In 1993, he illage ea men s we e (1) shallow cul i a ion o 12 cm,
J. Hy ¨
aluoma e al.
Soil & Tillage Resea ch 245 (2025) 106323
2
(2) deep ploughing o 32 cm, and (3) con en ional ploughing o 22 cm.
In au umn 1994, he illage ea men s we e epea ed as in 1993. In
au umn 1995, all plo s we e cul i a ed o 10 cm dep h and in 1996
o o a ed o sowing dep h. In au umn 1997, he shallow o o a ing was
epea ed excep o he o iginal con en ional ploughing ea men ,
which was now deep ploughed using a sel -made special plough
designed o cu a shallow (ca. 5 cm) slice o he opsoil and d op i a he
bo om o he u ow. The ploughing was ca ied ou wice in a ow, i s
o 30 cm dep h and a e ha aiming a 40 cm dep h, bu a he end, a
ploughing dep h o 35 cm was eached (Saa ela e al., 2000). The illage
ea men s a e summa ized in he supplemen a y ma e ial, Table S1.
The expe imen al plo s we e main ained un il 2007.
A e he ield expe imen was discon inued, he whole a ea has been
unde uni o m ag icul u al managemen (see supplemen a y ma e ial,
Table S2). The expe imen al ield was unde g ass p oduc ion o a ou -
yea pe iod 2008–2012. The ea e he ield has been in ce eal p o-
duc ion excep o 2021 when a a bean was cul i a ed. A e 2013,
manu e has been sp ead on he ield annually wi h addi ional mine al
ni ogen e iliza ion, bu no lime has been applied. Tillage me hods
ex ending unde he no mal ploughing dep h (ca. 20 cm) ha e no been
used a e he e mina ion o he ield expe imen . The expe imen al
a ea hus encompasses con ol plo s o con en ional illage dep h (CT)
and wo se s o plo s deep ploughed in he 1990s (DP1 and DP2). DP1
e e s o deep plough ea men wi h a comme cial moldboa d plough
o deep ploughing (Fiska s 1×20”) and DP2 o ploughing wi h a sel -
made plough.
2.2. Si e eloca ion and sampling
While he ield map and o de o he illage and liming plo s we e
a ailable in he documen a ion o he expe imen , he accu a e posi ion
o he expe imen al si e was no documen ed. Howe e , he si e was
isible in ae ial pho og aphs aken om he egion in 2004 and 2006/
2007 when he expe imen al plo s we e s ill main ained in he ield. The
ae ial pho og aphs a e a ailable in he Finnish na ional geopo al
Paikka ie oikkuna main ained by he Na ional Land Su ey o Finland
(h ps://ka a.paikka ie oikkuna. i). Al hough he e is a small inaccu-
acy in he posi ioning o he si e co ne s (ca. 1 m), he la ge size o he
plo s made i possible o a ge he soil sampling o co ec ea men s.
Soil samples we e collec ed om he eloca ed expe imen al si e in
June 2022. On he longi udinal cen al line o each main plo , h ee
sampling poin s we e se such ha one poin was placed in he cen e o
each h ee spli -plo s o di e en liming ea men s (in o al 27 sampling
poin s, see Fig. 1). All sample ypes we e aken om he same sampling
loca ions. The small spli -spli -(spli ) plo s o a ying P e iliza ion
could no be conside ed in he sampling. Soil co e samples we e aken
sepa a ely om each o he sampling poin s in 10-cm segmen s down o
50-cm dep h wi h an auge o 4.8 cm in diame e . In addi ion, dis u bed
composi e samples we e collec ed om 0 o 20 cm opsoil and 20–40 cm
subsoil laye s by bulking soil co es o ca. 2 cm in diame e om all h ee
sampling poin s o he main plo .
Fo X- ay omog aphy imaging, in ac soil co es we e sampled om
he sampling poin s in aluminium cylinde s wi h an inne diame e o
46 mm and a heigh o 70 mm. F om each sampling poin , one sample
was aken om opsoil and one om subsoil. The sampling dep hs we e
app oxima ely 10–15 cm and 25–30 cm, espec i ely. Fo bo h sampling
dep hs, h ee samples om each illage plo we e sampled such ha one
sample was aken om each liming plo . Thus, in o al 54 soil co es o
imaging we e collec ed. The collec ed soil samples we e w apped wi h
plas ic ilm o p ese e hei na u al soil mois u e and s o ed a +5 ◦C
un il imaging. In addi ion, subsoil samples o wa e e en ion mea-
su emen s we e aken om ca. 25–30 cm soil dep h o cylinde s wi h an
inne diame e o 72 mm and a heigh o 60 mm. Sampling loca ions
we e he same as o imaging samples, i.e., in o al 27 samples o wa e
e en ion measu emen s we e collec ed. The sampling imes o opsoil
and subsoil samples we e 29 h June and 26 h Sep embe 2022,
espec i ely. Wa e e en ion samples we e also co e ed and s o ed a
+5 ◦C be o e measu emen s.
To assess possible di e ences in c op g ow h be ween he p e ious
illage ea men s, a emo e sensing da ase o he ield si e was collec ed
on 14 h July 2022 wi h an unmanned ae ial ehicle (UAV) DJI Ma ice
RTK V2 quadcop e equipped wi h a Micasense Al um adiome ic
mul ispec al came a. The ligh al i ude was 80 m and a e o homo-
saicing, he pixel size o he image was 5.3 cm. In addi ion, whole abo e-
g ound biomass samples o ipe ba ley (Ho deum ulga e) we e
collec ed om each sampling poin on 1s Sep embe 2022, by cu ing
he c op a 4-cm heigh wi hin a 50 cm ×50 cm ame.
2.3. Labo a o y analyses
The soil co e samples we e d ied a 40 ˚C and weighed o bulk
densi y. The ea e , he samples we e g ound o pass a 2-mm sie e and
analysed o o al C ia d y combus ion (Leco 628 CHN De e mina o ),
which in he acidic soil can be aken o ep esen o ganic C (Nelson and
Somme s, 1996). C s ocks in soil p o iles we e calcula ed using he
equi alen soil mass me hod wi h he C concen a ions de e mined o
he 10-cm soil laye s. S ocks we e calcula ed o ep esen a 600 kg m
−2
mine al soil laye , which co esponded o soil dep hs be ween 43 and
50 cm. Calcula ions we e done as desc ibed by Heikkinen e al. (2021).
Concen a ions o SOC we e conside ed in 0–20 cm and 20–40 cm
opsoil and subsoil laye s. Fo his pu pose, an a e age weigh ed by bulk
densi y was calcula ed o e he SOC concen a ions de e mined in he
10-cm segmen s.
Fo analyses o pH and elec ical conduc i i y (1:2.5 wa e suspen-
sion) samples ep esen ing 0–20 cm and 20–40 cm dep hs we e con-
s uc ed om he co e samples aken in 10-cm segmen s by mixing equal
olumes o samples om he wo laye s. Fo he analysis o soil pa icle
size dis ibu ion ( ex u e) by he pipe e me hod o Elonen (1971),
samples om he h ee sampling poin s in each plo we e u he com-
bined o o m one ep esen a i e sample o each plo om bo h
0–20 cm and 20–40 cm laye s.
The composi e soil samples aken om each plo we e size and
densi y ac iona ed o assessing he soil C ese es in ee pa icula e
o m (POC) and mine al-associa ed o m (MOC) ollowing sligh ly
modi ied p ocedu e o Keskinen e al. (2024). In b ie , 50 g o esh soil
was dispe sed by shaking (18 h) in deionized wa e , and he ea e we
sie ed on sie es o 2 mm, 0.25 mm, and 0.063 mm mesh in succession.
The size ac ions we e o en-d ied a 80 ˚C. The ac ions o 0.25–2 mm
and 0.063–0.25 mm we e u he densi y sepa a ed in sodium poly-
ungs a e adjus ed o 1.8 g cm
−3
densi y o eco e ligh e POC and
hea ie MOC. The o al C concen a ion o all i e ac ions was analysed
ia d y combus ion (Leco 628 CHN De e mina o ). Fu he , he POCs
Fig. 1. Expe imen al si e imaged 14 h o July 2022. Rec angles wi h shades o
blue show he main plo s wi h di e en illage ea men s (con ol and wo deep
plough ea men s) and ec angles wi h shades o g ey he spli plo s wi h
di e en liming le els. The sampling poin s we e in he cen es o he 27
spli plo s.
J. Hy ¨
aluoma e al.
Soil & Tillage Resea ch 245 (2025) 106323
3
and MOCs in 0.25–2 mm and 0.063–0.25 mm size ac ions we e sum-
med up esul ing in h ee SOC ac ions: POC, MOC>0.063 mm and
MOC<0.063 mm.
The wa e e en ion p ope ies o subsoil samples we e de e mined
by using he UGT MP10 ku-pF appa a us (Umwel -Ge ¨
a e-Technik
GmbH, Ge many). Be o e measu emen , soil cylinde s we e sa u a ed
wi h wa e om below and a e his, wo mic o- ensiome e s we e
inse ed ho izon ally in d illed holes a a heigh di e ence o 3 cm. A e
being placed in he appa a us, he samples we e weighed and he
ensiome e eadings we e ead au oma ically in 10-min in e als un il
he ai -en y ension o he ensiome e s was eached (ca. 85 kPa).
Du ing he measu emen , samples we e co e ed wi h 3D-p in ed
pe o a ed lids o es ain he e apo a ion a e and hus he ension
di e ence be ween he op and bo om o he samples. The ea e he
samples we e o en-d ied a 105 ◦C and he weigh losses in he samples
we e con e ed o olume ic wa e con en alues a each ime. The
po e olumes abo e and below 30 µm po e diame e ( ield capaci y)
we e conside ed, which also app oxima ely co esponds o he po osi y
isible and in isible in he X- ay omog aphy images, espec i ely.
No malized di e ence ege a ion index (NDVI) was calcula ed om
he emo e sensing da a o es ima e he g ow h in di e en ield plo s.
NDVI index is de ined as NDVI =(NIR-Red)/(NIR+Red), whe e NIR and
Red s and o he calib a ed e lec ance alues o nea -in a ed and ed
bands, espec i ely. Fu he de ails o he UAV imaging app oach can be
ound in Niemi alo e al. (2021). The abo e-g ound ce eal biomass was
o en-d ied a 60 ◦C o 6 days and he ea e weighed.
2.4. Image analysis
Soil po osi y, c i ical po e size and po e size dis ibu ion we e
de e mined using an in-house buil JTomo X- ay omog aph. X- ays
we e gene a ed wi h an L12161 X- ay ube (Hamama su Pho onics,
40–150 kV, 75 W) and sou ce ol age and powe we e se o 150 kV and
30 W, espec i ely, in medium ocus mode. Inciden X- ays we e il e ed
wi h a 6 mm hick glass il e . Radiog aphs we e acqui ed wi h a Shad-o-
Box 6k HS la panel de ec o (Teledyne) in cone-beam geome y. In
each scan ei he 5880 o 2940 p ojec ions o e 360 deg ees we e
cap u ed wi h 500 ms exposu e ime and 20 µm pixel size. Each sample
was imaged a wo e ical posi ions o co e i in i s en i e y.
Recons uc ion o omog aphs (Fig. 2a) and image analysis was done
wi h pi2 so wa e (a ailable a gi hub.com/a umie inen/pi2) Recon-
s uc ion o omog aphs was pe o med using he Feldkamp-Da is-K ess
Fil e ed Backp ojec ion algo i hm (Feldkamp e al., 1984). A e
econs uc ion, he wo omog aphs we e s i ched o a single 3D olume
using NRS i che so wa e (Mie inen e al., 2019).
The imaging noise was educed (Fig. 2b) om he s i ched images
wi h bila e al il e (spa ial sigma =40 µm, adiome ic sigma =3500)
and images we e scaled o 40 µm pixel size. Segmen a ion o images was
hen done by h esholding all samples wi h he same h eshold alue.
The h eshold alue was manually selec ed so ha i yielded he isually
mos accu a e sepa a ion o oid and solid phases.
Po osi y was calcula ed om he segmen ed bina y images (Fig. 2c).
In he po osi y analysis, he op and bo om pa s o he sample we e
excluded o a oid analysing possible damaged pa s o he sample due o
Fig. 2. a) Recons uc ed c oss-sec ion o a soil sample. b) A smalle egion be o e and a e bila e al il e ing. c) Segmen a ion o he same c oss-sec ion, whe e oids
a e shown as whi e and d) local hickness map o he segmen a ion. The colou ba in d) shows po e diame e alues in pixels.
J. Hy ¨
aluoma e al.
Soil & Tillage Resea ch 245 (2025) 106323
4
sample collec ion. Po e diame e dis ibu ion was calcula ed om local
hickness maps (Fig. 2d) o oid space wi h s a is ical binning
(Hildeb and and Ruegsegge , 1997).
The la ges sphe e ha can a el h ough he oids in he sample is
called c i ical po e size (Koes el e al., 2018; Ka z and Thompson, 1986).
The c i ical po e size was calcula ed h ough an i e a i e lood- ill p o-
cess. Fi s , he local hickness map was h esholded by he la ges po e
size, di iding he image in o space consis ing o oids la ge han he
h eshold alue, and e e y hing else. I a lood ill p ocess s a ed a he
oid space abo e he sample could no p og ess o he oid space below
i h ough he la ge oids, he h esholding po e size alue was
dec eased by 1 pixel and he p ocess was epea ed. The c i ical po e size
was de ined as he i s h eshold alue ha esul ed in he lood ill
being able o p opaga e h ough he sample.
2.5. S a is ical analyses
The expe imen al design was a andomized spli -plo expe imen
wi h h ee blocks, whe e plough ea men was used as he whole plo
and lime ea men as he subplo . In addi ion, measu emen s we e
aken om wo dep hs om each plo .
The analyses o esponse a iables measu ed a wo dep hs we e
pe o med wi h, gene alized linea mixed models (GLMM) wi h plough
ea men (CT, DP1, DP2), lime ea men (LL, ML, and HL), dep h
(0–20 cm, 20–40 cm) and all hei in e ac ions we e deno ed as ixed
e ec s. The andom e ec s o block, block ×plough ea men , and
block ×dep h we e assumed o be independen and no mally dis ib-
u ed. Fo hose esponse a iables ha ing measu emen s only om he
one soil laye , he model was simpli ied omi ing he e ec o dep h om
he models.
Co ela ions be ween dep hs we e aken in o accoun using a he -
e ogeneous o homogeneous compound symme y (CSH o CS) co a i-
ance s uc u e. He e ogenous s uc u es also allow non-cons an
a iance. The Akaike’s In o ma ion C i e ion (AICc) was used o choose
he mos sui able co a iance s uc u e o each model.
An iden i y link was used o he Gaussian-dis ibu ed models. Due o
skewed esponse a iables, he assump ion o gamma dis ibu ion wi h a
log link was used o C concen a ion, equal soil mass-based SOC s ocks,
and imaged po osi ies o opsoil and subsoil. The esidual pseudo-
likelihood (RSPL) es ima ion me hod o he models ha ing he
gamma dis ibu ion assump ion, and he esidual maximum likelihood
(REML) me hod o he Gaussian-dis ibu ed models we e used. Deg ees
o eedom we e calcula ed using he Kenwa d-Roge me hod. The
no mali y o he esiduals was ound adequa e using boxplo s. Deep
plough ea men s and dep hs we e compa ed o he con ol ea men
(CT) and o he opsoil laye (0–20 cm), and hus he me hod o Dunne -
Hsu was used o all pai wise compa isons o means wi h a signi icance
le el o 0.05. Due o he small s udy size, also esul s ending owa ds
s a is ical signi icance (0.05<p<0.10) a e p esen ed and deno ed as
‘ma ginally signi ican ’. The analyses we e pe o med using he GLIM-
MIX p ocedu e in he SAS En e p ise Guide 8.3 (SAS Ins i u e Inc., Ca y,
NC, USA).
3. Resul s and discussion
3.1. Gene al ea u es
The expe imen al a ea p o ed o be o e all a he uni o m in ex u e.
Howe e , acco ding o he main plo soil samples (n=9), clay con en
was signi ican ly highe in he 0–20 cm soil laye o he deep ploughed
plo s (DP1 and DP2) han in he con ol plo s (p=0.025 and p=0.0087,
espec i ely, Table 1). In he 20–40 cm soil laye , he e we e no sig-
ni ican ex u al di e ences. The small e ec o he DP ea men s on he
ex u al composi ion o he opsoil is explained by he subsoil iche in
clay being mixed in he opsoil due o deep in e ing o he soil p o ile.
The lack o e ec in he subsoil may de i e om a smalle ela i e e ec
o a s eep ex u al dep h g adien wi hin he 20–40 cm subsoil since
al hough mouldboa d ploughing bu ies he opmos soil e icien ly,
edis ibu ion o he laye a he e y bo om has been shown o be less
e icien (Scanlan and Da ies, 2019).
The p e ious liming ea men s ca ied ou on spli -plo s s ill showed
a signi ican e ec on soil pH (p <0.001) he mean pH inc easing wi h
an inc ease in lime applica ion a e. O e all, pH was lowe in he opsoil
(5.9 LL; 6.4 ML; 6.5 HL), han in he subsoil (6.3 LL; 6.5 ML; 6.6 HL). The
illage ea men s showed no e ec on soil pH (p =0.127). Rega ding
he long- e m e ec s o liming, Holland e al. (2019) conside ed wo
long- e m liming expe imen s and epo ed ha he de ia ing pH
ollowing he lime applica ion pe sis ed o e a decade. Benne e al.
(2014), on he o he hand, did no ind s a is ically signi ican di e -
ences be ween liming and non-limed con ol in a sampling pe o med 12
yea s a e lime applica ion bu obse ed signi ican di e ences in hy-
d aulic conduc i i y and agg ega e s abili y. Al hough he e ec s o
liming a e known o depend on he soil p ope ies such as ex u e and
o ganic ma e con en (Holland e al., 2018), hese s udies demons a e
ha liming can ha e e ec s on soil p ope ies pe sis ing on a decadal
ime scale as also obse ed in he p esen s udy. Manu e applica ion has
been epo ed o ha e a liming e ec on soil (Eghball, 1999; Whalen
e al., 2000), which may also a ec he obse ed esul s, as manu e has
been sp ead o he s udy ield equen ly. The de ec able e ec s o he
liming his o y can also be aken o con i m ha he posi ioning o he
ield expe imen was success ul despi e he lack o exac coo dina es.
Simila ly o pH, a signi ican e ec on soil elec ical conduc i i y
(EC) was eco ded o dep h (96 µS cm
−1
a 0–20 cm and 63 µS cm
−1
a
20–40 cm; p <0.001) bu no o illage (p =0.794). Di e ences in he
liming his o y we e nei he e lec ed in he p esen EC alues (p =
0.303). The EC alue e lec s he p esence o soluble sal s in soil (Ha die
and Doyle, 2012), and highe EC a he opsoil in compa ison o he
subsoil can be a ibu ed o inpu s o mine al e ilize s and manu e.
3.2. Soil ca bon
3.2.1. Soil ca bon concen a ion and s ock
Only a ma ginally signi ican main e ec on SOC concen a ion was
ound o he illage ea men (p =0.079) bu he illage and plough
dep h had a signi ican in e ac ion e ec (p =0.016; Fig. 3a). This was
mani es ed as a sligh ly lowe SOC concen a ion in he opsoil o DP2 in
compa ison o he opsoil o CT (2.63 % s. 2.80 %; ma ginally signi i-
can , p =0.058) and secondly as a highe SOC concen a ion in he
subsoil o DP1 in compa ison o he subsoil o CT (1.31 % s. 1.01 %; p =
0.048). A ma ginally signi ican di e ence be ween DP1 and CT could
also be seen in ca bon s ock when calcula ed o he equi alen dep h o
20–40 cm (DP1 3.83 kg C m
−2
, CT 2.89 kg C m
−2
; p =0.053). Howe e ,
in equal mass-based SOC s ocks o 600 kg m
−2
, no signi ican di e ences
be ween he illage ea men s occu ed (CT 10.0 kg C m
−2
, DP1
10.6 kg C m
−2
, DP2 9.7 kg C m
−2
; p =0.215, Fig. 3b). No signi ican
e ec on SOC was obse ed ei he o lime ea men (p =0.382) bu
o e all, SOC dec eased wi h dep h (p <0.001).
The lack o sys ema ic e ec o deep illage on SOC concen a ions o
s ocks likely pa ly o igina es om he sampling design. The sampling
Table 1
Clay (<0.002 mm), sil (0.002–0.02 mm) and sand (0.02–2 mm) con en s in
0–20 cm and 20–40 cm soil laye s in con ol (CT) and deep-ploughed plo s (DP1
and DP2). Tillage ea men s di e ing signi ican ly (p<0.05) om he con ol
ea men a e ma ked wi h an as e isk (*).
CT DP1 DP2
0–20 cm Clay 44.9 46.4* 46.8*
Sil 30.8 30.2 30.3
Sand 24.3 23.4 22.9
20–40 cm Clay 59.1 58.3 60.0
Sil 26.2 26.1 26.0
Sand 14.7 15.7 14.0
J. Hy ¨
aluoma e al.
Soil & Tillage Resea ch 245 (2025) 106323
5
pa e n consis ing o single sample poin s on he cen e line o each plo
could no cap u e he a ia ion o he e ogenei y in he subsoil de i ed
om he u ow slices (Scanlan and Da ies, 2019). The sampling was
hus a he non-sensi i e o small changes. In case o mo e esou ces,
inc easing he sample numbe o, e.g., h ee pa allel poin s in each
sampling loca ion o co e he wid h o he u ow would be ecom-
mendable (e.g., Alc´
an a a e al., 2016). Howe e , he lack o a clea
signi ican inc ease in SOC s ocks a e nea ly 30 yea s om he illage
ope a ions does no in his case suppo he hypo hesis o enhanced SOC
acc ual ia he less C-sa u a ed mine al su aces o he subsoil in com-
pa ison o opsoil. The plough dep h (ca. 35 cm) used in he s udy si e
was shallowe he e han hose conside ed in some o he s udies ocusing
on he impac s o deep ploughing. Fo example, Alc´
an a a e al. (2016)
s udied deep plough si es whe e he plough dep h a ied be ween 55
and 90 cm. While he plough dep h may pa ly explain he milde e-
sul s, he plough dep h ne e heless was clea ly deepe han he con-
en ional ploughing dep h (ca. 20 cm) used in he egion (Tu ola e al.,
2007). Deep ploughing may also ha e ad e se e ec s on SOC acc ual
h ough he so-called p iming e ec . The in oduc ion o easily
decomposable o ganic ma e o subsoil may igge he mine aliza ion
o old s abilized SOC s o ed in he deepe soil laye s (Fon aine e al.,
2007). Howe e , he esul s o he p iming e ec in subsoil a e incon-
clusi e. Fo example, in mic ocosm incuba ions by Wo dell-Die ich
e al. (2017), he same o ganic ma e addi ion decomposed slowe in
he subsoil han in opsoil and he added o ganic ma e did no lead o
accele a ed mine aliza ion o na i e SOC. Dai e al. (2022), in u n,
ound ha o ganic ma e addi ion esul ed in a posi i e p iming e ec
bo h in opsoil and subsoil, bu he e ec was s onge in opsoil.
3.2.2. Soil ca bon in mass and densi y ac ions
O he o al OC in he composi e soil samples, 13 % was eco e ed in
he POC ac ion in he 0–20 cm soil laye and 7.7 % in he 20–40 cm
laye . O he o al OC, 11 % (bo h laye s) we e la ge -sized MOC
(>0.063 mm), and 75 % (0–20 cm) and 81 % (20–40 cm) MOC smalle
han 0.063 mm. The sha es o POC and MOC all wi hin sha es epo ed
o simila soil (Salonen e al., 2023). The mean POC concen a ion was
clea ly highe in he 0–20 cm laye (0.34 mg C (100 g)
−1
soil) han in
he 20–40 cm dep h (0.12 mg C (100 g)
−1
soil) (p<0.0001). The e we e
Fig. 3. (a) Ca bon concen a ions and hei 95 % con idence in e als in opsoil (0–20 cm) and subsoil (20–40 cm) laye s o he illage ea men s (con ol CT and
wo deep plough ea men s DP1 and DP2). (b) Ca bon s ock in he opsoil and subsoil laye s.
Fig. 4. Bulk densi ies and hei 95 % con idence in e als o opsoil (0–20 cm) and subsoil (20–40 cm) laye s o he illage ea men s (con ol CT and wo deep
plough ea men s DP1 and DP2).
J. Hy ¨
aluoma e al.
Soil & Tillage Resea ch 245 (2025) 106323
6
no s a is ically signi ican di e ences be ween he illage ea men s in
he MOC o POC concen a ions in he 0–20 cm laye bu in he
20–40 cm laye , he POC concen a ion in DP2 was ma ginally highe
han in CT (p=0.064) (Table 2), which may e lec he p esence o
o me opsoil ma e ial. Below 20 cm, he sum o all C ac ions esul ed
in highe SOC concen a ion ha measu ed om he p o ile co es
sampled down o 40 cm dep h. This may sugges ha he soil sample
om 20 o 40 cm aken wi h he hinne 2-cm auge was con amina ed
wi h he su ace soil while sampling.
The esul s hus indica ed, ha du ing he yea s ollowing pa ial
mixing o he soil laye s di e ing in SOC con en s, he MOC ac ion in
he su ace soil (0–20 cm) o he deep-ploughed plo s likely app oached
he SOC con en le els o he con ol ea men , esponding simila ly o
he same managemen p ac ices applied ac oss he ield. Despi e ex-
pec a ions ha deep ploughing would inc ease MOC con en in deepe
soil laye s, his was no obse ed. Though he MOC ac ion is o e all
mo e s able and esis an o changes in managemen and en i onmen
han he POC ac ion, i is ne e heless di e se and o some ex en
cycling (Sokol e al., 2022). Mo e esea ch on he pa hways o MOC
o ma ion and i s e en ion in he subsoil condi ions is needed.
3.3. Soil s uc u al p ope ies
The e ec o illage ea men on opsoil bulk densi y was signi ican
(p=0.017) and pai wise compa isons showed di e ence be ween CT and
DP1 ea men s (p=0.043). Lime ea men did no show s a is ically
signi ican e ec s (p=0.85).
Rega ding he image analysis esul s, no signi ican e ec be ween
illage ea men s was de ec ed o opsoil mac opo osi y (CT 0.12, DP1
0.11, DP2 0.10; p=0.61) o c i ical po e diame e (553 µm, 536 µm,
514 µm; p=0.945). Simila ly o illage, nei he did liming ea men
show a signi ican e ec on hese quan i ies (p=0.496 and 0.457,
espec i ely). Howe e , mac opo osi y had a ma ginally signi ican
in e ac ion e ec be ween illage and liming ea men s (p=0.082). Fo
subsoil mac opo osi y, no signi ican di e ences we e de ec ed (CT
0.023, DP1 0.041; DP2 0.023; p=0.29). The e ec o illage ea men on
subsoil c i ical po e diame e was signi ican (CT 259 µm, DP1 415 µm,
DP2 190 µm; p=0.0281). Pai wise compa ison showed no signi ican
di e ence be ween CT and DP ea men s, e en hough he subsoil
c i ical po e diame e o DP1 was clea ly la ge han in CT.
Wa e e en ion measu emen s we e only done o subsoil samples.
Tillage ea men showed no signi ican e ec on he o al subsoil
po osi y de e mined om he wa e e en ion measu emen s (CT 0.48,
DP1 0.47, DP2 0.48; p=0.607), whe eas liming ea men had a signi -
ican e ec (HL 0.48, ML 0.49, LL 0.47; p=0.0015) and a ma ginally
signi ican in e ac ion e ec was de ec ed be ween illage and lime
ea men (p=0.0839). Pai wise compa isons showed signi ican di -
e ences be ween HL and ML (p=0.04) as well as ML and LL (p=0.001)
ea men s. Po osi ies o wo po e size classes we e conside ed om he
wa e e en ion cu es namely po es wi h a diame e less o g ea e han
30 µm, which co esponds o he ield capaci y and app oxima ely also
he esolu ion o X- ay omog aphy. Fo po e sizes less han 30 µm, lime
ea men had a ma ginally signi ican e ec on po osi y (HL 0.42, ML
0.43, LL 0.41; p=0.089) whe eas illage ea men showed no signi ican
e ec (0.42 o all illage ea men s; p=0.98). Pai wise compa isons
showed a ma ginally signi ican di e ence be ween LL and ML ea -
men s (p=0.078). Fo he la ge po e size class, no signi ican e ec due
o illage (CT 0.059, DP1 0.054, DP2 0.062; p=0.609) o liming (HL
0.058, ML 0.061, LL 0.056; p=0.743) was obse ed.
In gene al, ou esul s show ha deepened ploughing has had only
mino and sca e ed e ec s on soil s uc u al p ope ies. Nei he wa e
e en ion measu emen no X- ay omog aphy showed di e ences in
mic opo osi y be ween he illage ea men s. Wa e e en ion mea-
su emen s indica ed di e ences be ween liming ea men s, bu he
di e ences a e mino as compa ed o, e.g., di e ences obse ed be ween
di e en soil managemen p ac ices in he opsoil o simila bo eal clay
soils (Hy ¨
aluoma e al., 2024). I should be no ed, howe e , ha bo h
measu emen echniques used ocused on he mac opo e egime,
whe eby he e may be di e ences in mic opo e and mesopo e egimes
which comp ise mos o he o al po osi y. Image analysis showed di -
e ences in he subsoil c i ical po e diame e be ween illage ea men s.
The e o e, despi e compa able mac opo osi ies, he mac opo e con-
nec i i y di e s be ween he ea men s which can lead o di e ences in
soil unc ioning as pe cola ion heo y links he sa u a ed hyd aulic
conduc i i y o c i ical po e diame e ia a powe law (Ka z and
Thompson, 1986). Pe cola ion heo y has been ound o desc ibe he
hyd aulic conduc i i y o soils in se e al s udies (Ghanba ian e al.,
2017; Koes el e al., 2018; Soinne e al., 2023; Hy ¨
aluoma e al., 2024).
Thus, ou esul s sugges ha deep ploughing can lead o long- e m e -
ec s on subsoil hyd aulic unc ions. In o al, he esul s do no easse
he conce ns abou he ha m ul e ec s o deep ploughing on he soil
s uc u e and unc ions (e.g., Ba eye e al., 2020) a leas a he ime
scale and ploughing dep h conside ed he e. The s uc u al e ec s o
deep ploughing ha e been ound o be si e-speci ic and especially soil
ex u e can be assumed o be a key ac o . Fo example, Bu ge e al.
(2023) s udied he e ec s o deep ploughing on se e al soil p ope ies 50
yea s a e he deep ploughing e en a h ee si es and concluded ha
deep ploughing had si e-speci ic legacy e ec s on he soils. Deep
ploughing on sandy soils had led o educed subsoil bulk densi y
whe eas he e ec on sil y soil was he opposi e. The s udy by Baum-
ha d e al. (2008) conside ed bulk densi y on deep-ploughed clay loam
and ound ha he lowe ed subsoil bulk densi y obse ed ou yea s
a e deep ploughing was s ill p esen bu diminished when de e mined
31 yea s a e ploughing.
3.4. C op g ow h
The NDVI indices indica ed no di e ences in he g eenness o he
ege a ion be ween illage plo s bu a s a is ically signi ican (p =
0.0006) inc ease in NDVI was ound wi h an inc ease in p e ious liming
a e. This e ec was, howe e , p ac ically insigni ican as all mean NDVI
alues exceeded 0.9 (see Fig. 1). The mean o al abo eg ound biomass o
ipe c ops was highe in CT (8252 kg ha
−1
) han in he deep ploughed
plo s (DP1 7267 kg ha
−1
; DP2 7847 kg ha
−1
), bu he main e ec o he
illage ea men was me ely ma ginally signi ican (p =0.0881).
Consis en ly, in pai wise compa isons CT di e ed ma ginally om DP1
(p =0.0551). The esidual e ec o liming on c op g ow h was also only
ma ginally signi ican (p =0.0869) al hough he lowes liming le el
esul ed in he lowes mean yield.
Ou esul s showed a sligh nega i e c op esponse end as yields
we e 12 % and 5 % lowe in DP1 and DP2 as compa ed o CT. Recen ly,
Bu ge e al. (2023) s udied h ee Ge man si es ( wo sandy and one sil y
soil) i e decades a e he deep ploughing and obse ed posi i e yield
e ec s due o deep ploughing a one sandy soil in d y condi ions while
he e ec s we e mino and no signi ican o he wo o he si es. A
me a-analysis based on a la ge numbe o yield compa isons showed ha
on a e age deep illage had a sligh ly posi i e e ec on c op yield
(+6 %) (Schneide e al., 2017). Rega ding he c op esponse o deep
illage, soil ex u e was ecognized as a key a iable, whe eby he
Table 2
Pa icula e o ganic ca bon (POC) and mine al-associa ed o ganic ca bon (MOC)
in <0.063 mm and >0.063 mm size ac ions. Tillage ea men s ha di e
ma ginally signi ican ly (p<0.10) om he con ol a e ma ked wi h a ci cle (◦).
CT DP1 DP2
mg C (100 g)
¡1
soil
0–20 cm POC 0.35 0.32 0.35
MOC >0.063 mm 0.30 0.31 0.27
MOC <0.063 mm 1.92 1.96 1.90
20–40 cm POC 0.10 0.09 0.17◦
MOC >0.063 mm 0.16 0.20 0.16
MOC <0.063 mm 1.18 1.16 1.32
J. Hy ¨
aluoma e al.
Soil & Tillage Resea ch 245 (2025) 106323
7
success o deep illage depends on si e-speci ic soil p ope ies (Schneide
e al., 2017). In pa icula , he e ec s o deep ploughing we e conside ed
nega i e on sil y soils. Håkansson e al. (1998) a ibu ed he nega i e
yield e ec on high-sil soils o de e io a ed su ace s uc u e and
consequen su ace laye ha dening due o he dilu ion o SOM. In clay
and sandy soils, he main easons behind posi i e yield e ec s o
deepened illage we e deepe loosening and mo e e icien weed con ol
han in shallow ea men .
4. Conclusions
A deep ploughing and liming expe imen ha was es ablished ca. 30
yea s ea lie was e isi ed o in es iga e he legacy e ec s o hese
managemen p ac ices on SOC s ocks, soil s uc u e and yield. We ound
mino di e ences in opsoil ex u e due o deep ploughing and some
indica ions o lowe ed SOC concen a ion in he opsoil and inc eased
subsoil SOC concen a ion, which may indica e a ans e o he opsoil
SOC o deepe laye s and dilu ion o he SOC in he opsoil due o deep
ploughing. Howe e , we did no obse e signi ican di e ences in SOC
s ocks be ween he illage ea men s. Thus, ou esul s did no indica e
majo SOC seques a ion e ec s due o deep ploughing epo ed in some
p e ious s udies. Compa ed wi h o he s udies whe e he e ec s o deep
ploughing ha e been conside ed, he plough dep h in he ield expe i-
men conside ed he e was shallowe , which may pa ly explain he
milde esul s. The plough dep h (35 cm) was ne e heless deepe han
ha ypically used o hese soils (20–25 cm). We also s udied he soil
s uc u al p ope ies and ound only mino and sca e ed impac s be-
ween illage ea men s, whe eby he deepened plough had no caused
long-las ing ex ensi e s uc u al damage o he soil s uc u e bu nei he
any bene i s o he subsoil laye . Rega ding he liming ea men s, we
s ill ound ha inc easing liming a es consis en ly induced di e ences
in soil pH a e h ee decades. To summa ize, ou esul s do no suppo
he possibili y o ema kably inc easing SOC s ocks in he subsoil laye
wi h deep ploughing, bu nei he could we ind signs o se e e s uc u al
damages ha would emain a e h ee decades, whe eas liming
appea ed o ha e he clea es long- e m impac s on he soil p ope ies.
Since he impac s o soil managemen ope a ions ca ied ou h ee de-
cades be o e he sampling we e s ill de ec able, ou esul s highligh he
impo ance o s udying he long- e m consequences o soil managemen
p ac ices. Fo an enhanced unde s anding o he e ec s o si e-speci ic
condi ions and e.g. ploughing dep h, u he s udies on he impac s o
deep illage on subsoil p ope ies and SOC acc ual a e s ill necessa y.
CRediT au ho ship con ibu ion s a emen
Vik o iia He manenko: W i ing – e iew & edi ing, In es iga ion.
Riikka Keskinen: W i ing – e iew & edi ing, W i ing – o iginal d a ,
In es iga ion, Concep ualiza ion. A u Mie inen: W i ing – e iew &
edi ing, So wa e, Me hodology. Sami Kinnunen: W i ing – e iew &
edi ing, W i ing – o iginal d a , Visualiza ion, In es iga ion, Fo mal
analysis. Ja i Hy ¨
aluoma: W i ing – e iew & edi ing, W i ing – o ig-
inal d a , Visualiza ion, In es iga ion, Concep ualiza ion. Janne
Kase a: W i ing – e iew & edi ing, W i ing – o iginal d a , Fo mal
analysis. Pe i Niemi: W i ing – e iew & edi ing, In es iga ion. Helena
Soinne: W i ing – e iew & edi ing, W i ing – o iginal d a , P ojec
adminis a ion, In es iga ion, Concep ualiza ion.
Decla a ion o Compe ing In e es
The au ho s decla e ha hey ha e no known compe ing inancial
in e es s o pe sonal ela ionships ha could ha e appea ed o in luence
he wo k epo ed in his pape .
Da a a ailabili y
Da a will be made a ailable on eques .
Acknowledgemen s
The wo k was pa o he Hiile In p ojec unded by he Minis y o
Ag icul u e and Fo es y o Finland h ough he Ca ch he Ca bon
esea ch and inno a ion p og amme. We hank Joonas Salmi o his
skil ul d one imaging.
Appendix A. Suppo ing in o ma ion
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online e sion a doi:10.1016/j.s ill.2024.106323.
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