Pengaruh pengapuran terhadap perilaku sulfat dan fosfat pada tanah Oxic Dystrudept dalam kaitannya dengan pertumbuhan dan produksi kacang tanah
PENGARUH PENGAPURAN TERHADAP
PERILAKU SULFAT DAN FOSFAT PADA TANAH
OXIC DYSTRLTDEPT DALAM KAITANNYA DENGAN
PERTUMBUHAN DAN HASIL KACANG TANAH
Oleh
I Gusti Putu Wigena
97 039/TNH
PROGRAM STUD1 ILMU TANAH
PROGRAM PASCASARJANA
INSTITUT PERTANIAN BOGOR
PENGARUH PENGAPLTRAN TERHADAP
PERILAKU SULFAT DAN FOSFAT PADATANAH
OXIC DYSTRUDEPT DALAM KAITANNYA DENGAN
PERTLMBUHAN DAN PRODUKSI KACANG TANAH
Oleh
I Gusti Putu Wigem
97 039lTNH
Tesis Sebagai Salah Sat. Syarat mtuk Meperoleh Gelar Magister Sains
pada
Program Pascasarjana Institut Pertanian Bogor
Program Studi Ilmu Tanah
PROGRAM PASCASARJANA
INSTITUT PERTANIAN BOGOR
SUMMARY
I Gusti Putu Wigena. The effects of lime on Sulfate and
Phosphate Behavior on Oxic Dystrudept in Relation witb Peanut
Growth and Yields. Thesis, under supervision of Abdul Rachim mead
of the Supervisor Commission), Astiana hstiono and I Putu Gedjer
W idjaja Ad hi (Members of the Supervisor Commission).
The objective of the research was to study the effects of lime to
behavior of sulfhte and phosphate in the soil namely transformation of
sulfur into sulfate, sulfate and phosphate adsorption capacity, interaction
between sulfate and phosphate, and its effects to peanut growth and yeld
on Oxlc Dystrudept.
The laboratory experiments were established on hboratory of
Chemical and Fertilization of Bogor Center for Soil and Agroclimate
Research, and field experiment was done on k c Dystmdept in Kubang
Ujo, Pauh Menang Village, Pamenang Sub District, Merangin District,
Jambi Province from June of 1999 to May of 2000.
Interaction of sulfate and phosphate experiment, which was
conducted at laboratory, was arranged in factoml experiment, using splitplot design and 3 replicahorn. 3 experimental factors namely methods of
sulfkte and phosphate application (P was applied 1 week earlier than S,
coded with A, P and S was applied at the same time, c d e d with B; and P
was applied 1 week later than S, coded with C) as main plot.
While, 16
combination treatments of 4 rates of sulfur (040; 5.0=S 1; 10.U=S2; and
15.0=S3 ppm S in soil solution) and 4 rates of phosphate
(*PO; 0.01=PI;
0.02=P2;and 0.03=P3 ppm P in soil solution) as sub plot. The field
experiment also use the same methodology and replication, where 3 levels
of lime (0; 0.5; and 1.0 exchangeable A1 or equal with 0;850, and 1700 kg
CaCQJhectare) as main plot. Ten combination treatments of 4 rates of
sulfate (%SO; 2.5=SI; 5 . 0 4 2 ; and 7.5=S3 pprn S in soil solution) and 4
rates of phosphate (*PO; O.Ol=Pl; 0.02=P2;and 0.03=P3ppm P in soil
solution) as sub plot. The ten combination treatments were chosen
accordvlg to Hauser Simplification Concept.
By application of this
methodolog;y, total experiment units of field experiment were 90 plots.
Results of h e experiment showed that application of lime and s u l h
could increased sulfur transformation at high rate at the early stage;
followd by the relative stabile rate at medium stage and low rate at the end
stage of transfomon. Liming at equal to 1.0 exchangeable A1 could
increase sulfur transformation as high as application of sulfur at
concentration of 5.0 pprn in soil solution. At the medium stage of
transformation, it was observed that concentration of sulfate in soil solution
a b u t 20.0 ppm. The combination treament of I -0exchangeable A1 of lime
with sulfbr at concentration of 10 ppm in soil solution showd the highest
of sulfate concentration in soil solution was about 120 ppm. The sub
surface soil, which has higher of sulfur content, all treatments that wre
applied at the surface soil gave higher of sulfate in soil solution of sub
surface soil was about 1-5 fold.
Maximum phosphate adsowon capacities of surface and sub
surface soils of the site were 1428.6 and 1250 pprn P, while maximum
sulfate adsorption capacities were 416.6 and 322.2 ppm S, respectively.
Liming at equal to 1.0 exchangeabie A1 decreased maximum adsorption
capacity of phosphate at the two soil surfkes become 1250 and 1 1 1 1.1 pprn
P, while maximum adsorption capacity of sulfate h o m e 212.8 and 181.8
ppm S, respectively. By assuming that the critical level of phosphate and
sulfate for crops growth in soil solution are 0.02ppm P and 5.0-10.0 ppm S,
a number of 1 00 ppm
P and 97 pprn S should be added from external to
achieve the critical concentration of P and S.
In term of the availability S and P,It was observed a weak synergism
interaction between sulfate and phosphate at all methods of P and S
application tested. By determining of sulfate and phosphate concentration in
soil solution, it was observed that the m e s t concenmtion of sulfate was
provided by application of phosphate 1 week earlier than sulfur (A), while
the highest of phosphate was obtained by applic&on of phosphate and
sulfur at the same tune (B).
Liming at equal of 1.0 exchangeable A1 tend to increase peanut
growth, while application of sulfur and phosphate increased peanut growth
significantly. It can be shown &om peanut height on the treatment of equal
of 1.0 exchangeable Al of lime combined with 7.5 ppm S and 0.03pprn P in
soil solution (S3P3) gave the highest plant height of h u t 48 cm, while
without lime combined with control treatment gave the lowest p h t height
of about 25 cm.
Liming also tend to increase dry pod and biomass of peanut, but
increased dry peanut seed significantly. Application of sulfur and phosphate
increased all the above parameters significantly. The highest yields of the
above parameters were obhned by S3P3 treatment of a b u t 9.03;4.03; and
2.77 kdplot. The lowst pel& of the parameters w r e obtained by control
treatment of about 2.13; 1.03 and 0.41 kg/plot, respectively.
Application of lime, sulfk and phosphate increased peanut seed
quality significantly. Liming until 1.0 exchangeable Al decreased empty
pod from 17.87% to 1I . 5%, and increase might of 1 00 peanut seed fiom
32.87 gram to 37.21 gram. The amino acids content of peanut seed namely
methionine, cistine, and cystein also increased by application of lime.
Methionine content of peanut seed increased from 0.56 pprn to 0.75 ppm;
cistine content from 0.58 ppm to 0.70 ppm, and cystein content from 0.39
pprn to 0.54 ppm. 1 -0exchangeable AI of lime combined with S3P3
treatment provided the best peanut seed quality where the empty pod was
observed about 8,67% and weight of 100 dry seed was 45.35 gram.
Methionine, cistine, and cystein content of peanut seed at this treatment
were observed about 0.88;0.80;and 0.62ppm. In contrast, the mrst peanut
seed quality was obtained by control treatment where empty pod about
25.67% and weight of 100 dry seed was 26.65 gram. Whik rnethionine,
cistine, and cystein content about 0.46; 0.48; and 0.3 1 ppm, respectrvely.
Application of lime until I . 0 exchangeable A1 or equal with 1 700 kg
CaC03/hectare changes some chemical properbes of the soil such as
increased soil pH from 4.4 to 5.03; increased P-available from 2.51 ppm to
2.84 ppm; S-available fiom 19.99 pprn to 25.4 ppm; Ca content from 1.8
me/100 gram to 4.44 mell OO gram; and base saturation fiom 26%to 54.9%.
On the other hand, aluminum saturation was decreased &om 42.5%
19.4%. Application of sulfur in the form of elemental
to
S decreased soil pH
from 4.6 to 4.4. While application of sulfur in the form of elemental S
combined with phosphate in the fonn of Rock Phosphate could increased P
and S available at all lime levels tested. Without lime, available-P increased
from 0.007ppm to 4.1 ppm P;and available3 from 1.13 ppm to 3 1.8 ppm.
At 0.5 exchangeable of lime treatment, available-P increased from 0.008
pprn to 4.2 pprn and available-S fiom 1.24ppm to 34.1 ppm. Meanwhile, at
1.O exchangeable AI, available-P increased from 0.007pprn to 4.7 ppm and
available-S from 1.33 pprn to 37.2 ppm.
Penelitian ini krtujuan untuk mempelajari pengaruh pernkrian
kapur terhadap perildm sulfat dan fosfat didalam tanah y t u transfonnasi
sulfur menjadi sulfat, empan sulfat dan fosfat, interaksi sulfat dan fosfat
serta pertumbuhan dm p d u k s i h a n g tanah p d a tanah Oxic Dystrudept .
Penelitian dilakukan di Laboratorium Kesubwan dan h i a Tanah
Pusat Penelitian Tanah dan AgroMimat Bogor dan percoban lapang pada
tanah Oxic Dystrudept Kubang Ujo, desa Pauh Menan& Kecamatan
Parnenang Kabupaten Merangin Propinsi Jambi dari b u h Juni 1999
sampai dengan bulan Mei 2000.
Penelitian interaksi sulfat dan fosfht yang diZakukan di labomtoriurn
menggunakan rancangan perlakwn factorial d m rancangan lingkungan
petak terpisah, diulang setmyak 3 kali. Sebanyak 3 faktor p t u 3 metode
pemberian sulfur dm fosfat (P diberi I minggu lebih am1 dam S den-
kode A; P dan S dikrikan secara b m a m m dengan kode B dan P
diberikan I minggu klakangan setelah S dengan kode C) sebagai petak
utarna. Sebanyak 16 perlakuan kombinasi 4 t a d S ( M O ; 5-S 1; 1+S2
dan 15 ppm S - l a m tanah =S3) d m 4 taraf P (+PO; 0,O1=P1; 0,02=P2
dm 0,03 ppm P-larutan tanah =P3) seb@ anak petak. Percobaan lapang
juga menggunakan metode penelitian dan ulangan yang sama dimana 3
taraf kapur (0;0,5 dan 1,O Alw atau setara dengan 0; 850 dan 1700 kg
CaC03/ha) sebagai petak utama. 10 perlakuan kombinasi dm 4 taraf S
(&SO; 2,5=S1; 5,0=S2 dan 7,5 ppm S-larutan tanah =S3) dan 4 taraf P
(O=PO;0,01=P1;0,02=P2 dan 0,03 ppm P-larutan t
a d =P3) yang dipilih
berdasarkan konsep penyederhanaan Hauser sebagai anak petak. Dengan
demikian total unit percobaan lapang sebanyak 90unit.
Hasil penelitian menunjukkan bahwa pemberian kapur dan sulfur
meningkatkan transformasi sulfur menjadi sulfat dengan poIa transformasi
yang relatif cepat pada awal, diikuti dengan laju transforrnasi yang relatif
stabil dan kemudian melambat p d a akhir pwiode penelitian. Pengapsampai dengan I,O & men-
transforrnasi sulfur harnpir sama
dengan pemberian s u l k sampai konsentasinya di dalarn larutan trrnah 5
ppm di mana pada saat transfonnasi cepaf sulfat yang terukur di d a h
larutan tanah lapisan atas mencapai 20 pprn. Kombinasi perlakuan 1,O A h
kapur dengan pemberian sulfur sampai konsentrasinya di dalam larutan
tanah 10 pprn meningkatkan transformasi sulfur tertinggi. Pada saat
transfonnasi cep* sulfat yang temkur pada perlakuan ini mencapai 120
ppm. Tanah lapisan b a d yang berkadar S lebrh bnggr, semua perlakuan
yang
&ternplan pada
lapisan bawah rnenyebabh
peningkatan
transformasi sulfur tanah lapisan bahwa sebanyak 1,5 kali lipat dari lapisan
atas.
maksimum sulfatnya masing-masing sbanyak 416,6 dan 3222 pprn S
Pemberian kapur sampai 1,0 & menurunkan erapan maksimum fosfat
pada lapisan atas clan bawah masing-masing menjadi 1 250 dan I I 1 1,l ppm
P, sedafigkan erapan maksimurn sulfat masing-masing menjadi 2 12,8 dan
18 1,8 pprn S. Dengan asumi bahwa konsentrasi kritis fosfat dan sulfkt
untuk pertumbuhan tanaman di dab larutan tanah masmg-masing 0,02
pprn P dan 5- 10 pprn S, maka dilihat dari kurva hubungan antara P dan S-
ditarnb*
dengan konsentrasi P dan S di d d m lamtan tanah, untuk
mencaw konsentrasi tersebut diperlukan penambahan fosfat dan sulfat
masing-masing sebanyak 100 pprn P dan 97 pprn S.
Tejadi interaksi sinergis yang lemah antara sulfat clan fosfat pada
semua metode pernberian sdfat
dan fosfat yang diuji. Dengan rnengukur
konsentrasi sulfat dan fosfat pada larutan tanah, diketahui bahm sulfit
tertinggi diperoleh pada rnetode pembenan fosfat 1 minggu lebih awal d m
pembenan sulfur (A). Sedangkan fosfat temggi diperoleh pa&
metode
pemberian fosfat bersamaan dengan sulfur (B).
Pengapuran sampai dengan 1,O Aha cenderung meninghtkan
pertumbuhan kacmg tanah, sedangkan pemberian sulfht dan fosfit
meningkatkan pertumbuhan k
g tanah secara nyata. Hal hi krlthat d m
tinggi tanaman kacang tanah pada perlakuan kapur 1,O & kombinasi
dengan pemberian sulfat dan fosfat wing-masing 7,5 ppm S d m 0,03 pprn
PERILAKU SULFAT DAN FOSFAT PADA TANAH
OXIC DYSTRLTDEPT DALAM KAITANNYA DENGAN
PERTUMBUHAN DAN HASIL KACANG TANAH
Oleh
I Gusti Putu Wigena
97 039/TNH
PROGRAM STUD1 ILMU TANAH
PROGRAM PASCASARJANA
INSTITUT PERTANIAN BOGOR
PENGARUH PENGAPLTRAN TERHADAP
PERILAKU SULFAT DAN FOSFAT PADATANAH
OXIC DYSTRUDEPT DALAM KAITANNYA DENGAN
PERTLMBUHAN DAN PRODUKSI KACANG TANAH
Oleh
I Gusti Putu Wigem
97 039lTNH
Tesis Sebagai Salah Sat. Syarat mtuk Meperoleh Gelar Magister Sains
pada
Program Pascasarjana Institut Pertanian Bogor
Program Studi Ilmu Tanah
PROGRAM PASCASARJANA
INSTITUT PERTANIAN BOGOR
SUMMARY
I Gusti Putu Wigena. The effects of lime on Sulfate and
Phosphate Behavior on Oxic Dystrudept in Relation witb Peanut
Growth and Yields. Thesis, under supervision of Abdul Rachim mead
of the Supervisor Commission), Astiana hstiono and I Putu Gedjer
W idjaja Ad hi (Members of the Supervisor Commission).
The objective of the research was to study the effects of lime to
behavior of sulfhte and phosphate in the soil namely transformation of
sulfur into sulfate, sulfate and phosphate adsorption capacity, interaction
between sulfate and phosphate, and its effects to peanut growth and yeld
on Oxlc Dystrudept.
The laboratory experiments were established on hboratory of
Chemical and Fertilization of Bogor Center for Soil and Agroclimate
Research, and field experiment was done on k c Dystmdept in Kubang
Ujo, Pauh Menang Village, Pamenang Sub District, Merangin District,
Jambi Province from June of 1999 to May of 2000.
Interaction of sulfate and phosphate experiment, which was
conducted at laboratory, was arranged in factoml experiment, using splitplot design and 3 replicahorn. 3 experimental factors namely methods of
sulfkte and phosphate application (P was applied 1 week earlier than S,
coded with A, P and S was applied at the same time, c d e d with B; and P
was applied 1 week later than S, coded with C) as main plot.
While, 16
combination treatments of 4 rates of sulfur (040; 5.0=S 1; 10.U=S2; and
15.0=S3 ppm S in soil solution) and 4 rates of phosphate
(*PO; 0.01=PI;
0.02=P2;and 0.03=P3 ppm P in soil solution) as sub plot. The field
experiment also use the same methodology and replication, where 3 levels
of lime (0; 0.5; and 1.0 exchangeable A1 or equal with 0;850, and 1700 kg
CaCQJhectare) as main plot. Ten combination treatments of 4 rates of
sulfate (%SO; 2.5=SI; 5 . 0 4 2 ; and 7.5=S3 pprn S in soil solution) and 4
rates of phosphate (*PO; O.Ol=Pl; 0.02=P2;and 0.03=P3ppm P in soil
solution) as sub plot. The ten combination treatments were chosen
accordvlg to Hauser Simplification Concept.
By application of this
methodolog;y, total experiment units of field experiment were 90 plots.
Results of h e experiment showed that application of lime and s u l h
could increased sulfur transformation at high rate at the early stage;
followd by the relative stabile rate at medium stage and low rate at the end
stage of transfomon. Liming at equal to 1.0 exchangeable A1 could
increase sulfur transformation as high as application of sulfur at
concentration of 5.0 pprn in soil solution. At the medium stage of
transformation, it was observed that concentration of sulfate in soil solution
a b u t 20.0 ppm. The combination treament of I -0exchangeable A1 of lime
with sulfbr at concentration of 10 ppm in soil solution showd the highest
of sulfate concentration in soil solution was about 120 ppm. The sub
surface soil, which has higher of sulfur content, all treatments that wre
applied at the surface soil gave higher of sulfate in soil solution of sub
surface soil was about 1-5 fold.
Maximum phosphate adsowon capacities of surface and sub
surface soils of the site were 1428.6 and 1250 pprn P, while maximum
sulfate adsorption capacities were 416.6 and 322.2 ppm S, respectively.
Liming at equal to 1.0 exchangeabie A1 decreased maximum adsorption
capacity of phosphate at the two soil surfkes become 1250 and 1 1 1 1.1 pprn
P, while maximum adsorption capacity of sulfate h o m e 212.8 and 181.8
ppm S, respectively. By assuming that the critical level of phosphate and
sulfate for crops growth in soil solution are 0.02ppm P and 5.0-10.0 ppm S,
a number of 1 00 ppm
P and 97 pprn S should be added from external to
achieve the critical concentration of P and S.
In term of the availability S and P,It was observed a weak synergism
interaction between sulfate and phosphate at all methods of P and S
application tested. By determining of sulfate and phosphate concentration in
soil solution, it was observed that the m e s t concenmtion of sulfate was
provided by application of phosphate 1 week earlier than sulfur (A), while
the highest of phosphate was obtained by applic&on of phosphate and
sulfur at the same tune (B).
Liming at equal of 1.0 exchangeable A1 tend to increase peanut
growth, while application of sulfur and phosphate increased peanut growth
significantly. It can be shown &om peanut height on the treatment of equal
of 1.0 exchangeable Al of lime combined with 7.5 ppm S and 0.03pprn P in
soil solution (S3P3) gave the highest plant height of h u t 48 cm, while
without lime combined with control treatment gave the lowest p h t height
of about 25 cm.
Liming also tend to increase dry pod and biomass of peanut, but
increased dry peanut seed significantly. Application of sulfur and phosphate
increased all the above parameters significantly. The highest yields of the
above parameters were obhned by S3P3 treatment of a b u t 9.03;4.03; and
2.77 kdplot. The lowst pel& of the parameters w r e obtained by control
treatment of about 2.13; 1.03 and 0.41 kg/plot, respectively.
Application of lime, sulfk and phosphate increased peanut seed
quality significantly. Liming until 1.0 exchangeable Al decreased empty
pod from 17.87% to 1I . 5%, and increase might of 1 00 peanut seed fiom
32.87 gram to 37.21 gram. The amino acids content of peanut seed namely
methionine, cistine, and cystein also increased by application of lime.
Methionine content of peanut seed increased from 0.56 pprn to 0.75 ppm;
cistine content from 0.58 ppm to 0.70 ppm, and cystein content from 0.39
pprn to 0.54 ppm. 1 -0exchangeable AI of lime combined with S3P3
treatment provided the best peanut seed quality where the empty pod was
observed about 8,67% and weight of 100 dry seed was 45.35 gram.
Methionine, cistine, and cystein content of peanut seed at this treatment
were observed about 0.88;0.80;and 0.62ppm. In contrast, the mrst peanut
seed quality was obtained by control treatment where empty pod about
25.67% and weight of 100 dry seed was 26.65 gram. Whik rnethionine,
cistine, and cystein content about 0.46; 0.48; and 0.3 1 ppm, respectrvely.
Application of lime until I . 0 exchangeable A1 or equal with 1 700 kg
CaC03/hectare changes some chemical properbes of the soil such as
increased soil pH from 4.4 to 5.03; increased P-available from 2.51 ppm to
2.84 ppm; S-available fiom 19.99 pprn to 25.4 ppm; Ca content from 1.8
me/100 gram to 4.44 mell OO gram; and base saturation fiom 26%to 54.9%.
On the other hand, aluminum saturation was decreased &om 42.5%
19.4%. Application of sulfur in the form of elemental
to
S decreased soil pH
from 4.6 to 4.4. While application of sulfur in the form of elemental S
combined with phosphate in the fonn of Rock Phosphate could increased P
and S available at all lime levels tested. Without lime, available-P increased
from 0.007ppm to 4.1 ppm P;and available3 from 1.13 ppm to 3 1.8 ppm.
At 0.5 exchangeable of lime treatment, available-P increased from 0.008
pprn to 4.2 pprn and available-S fiom 1.24ppm to 34.1 ppm. Meanwhile, at
1.O exchangeable AI, available-P increased from 0.007pprn to 4.7 ppm and
available-S from 1.33 pprn to 37.2 ppm.
Penelitian ini krtujuan untuk mempelajari pengaruh pernkrian
kapur terhadap perildm sulfat dan fosfat didalam tanah y t u transfonnasi
sulfur menjadi sulfat, empan sulfat dan fosfat, interaksi sulfat dan fosfat
serta pertumbuhan dm p d u k s i h a n g tanah p d a tanah Oxic Dystrudept .
Penelitian dilakukan di Laboratorium Kesubwan dan h i a Tanah
Pusat Penelitian Tanah dan AgroMimat Bogor dan percoban lapang pada
tanah Oxic Dystrudept Kubang Ujo, desa Pauh Menan& Kecamatan
Parnenang Kabupaten Merangin Propinsi Jambi dari b u h Juni 1999
sampai dengan bulan Mei 2000.
Penelitian interaksi sulfat dan fosfht yang diZakukan di labomtoriurn
menggunakan rancangan perlakwn factorial d m rancangan lingkungan
petak terpisah, diulang setmyak 3 kali. Sebanyak 3 faktor p t u 3 metode
pemberian sulfur dm fosfat (P diberi I minggu lebih am1 dam S den-
kode A; P dan S dikrikan secara b m a m m dengan kode B dan P
diberikan I minggu klakangan setelah S dengan kode C) sebagai petak
utarna. Sebanyak 16 perlakuan kombinasi 4 t a d S ( M O ; 5-S 1; 1+S2
dan 15 ppm S - l a m tanah =S3) d m 4 taraf P (+PO; 0,O1=P1; 0,02=P2
dm 0,03 ppm P-larutan tanah =P3) seb@ anak petak. Percobaan lapang
juga menggunakan metode penelitian dan ulangan yang sama dimana 3
taraf kapur (0;0,5 dan 1,O Alw atau setara dengan 0; 850 dan 1700 kg
CaC03/ha) sebagai petak utama. 10 perlakuan kombinasi dm 4 taraf S
(&SO; 2,5=S1; 5,0=S2 dan 7,5 ppm S-larutan tanah =S3) dan 4 taraf P
(O=PO;0,01=P1;0,02=P2 dan 0,03 ppm P-larutan t
a d =P3) yang dipilih
berdasarkan konsep penyederhanaan Hauser sebagai anak petak. Dengan
demikian total unit percobaan lapang sebanyak 90unit.
Hasil penelitian menunjukkan bahwa pemberian kapur dan sulfur
meningkatkan transformasi sulfur menjadi sulfat dengan poIa transformasi
yang relatif cepat pada awal, diikuti dengan laju transforrnasi yang relatif
stabil dan kemudian melambat p d a akhir pwiode penelitian. Pengapsampai dengan I,O & men-
transforrnasi sulfur harnpir sama
dengan pemberian s u l k sampai konsentasinya di dalarn larutan trrnah 5
ppm di mana pada saat transfonnasi cepaf sulfat yang terukur di d a h
larutan tanah lapisan atas mencapai 20 pprn. Kombinasi perlakuan 1,O A h
kapur dengan pemberian sulfur sampai konsentrasinya di dalam larutan
tanah 10 pprn meningkatkan transformasi sulfur tertinggi. Pada saat
transfonnasi cep* sulfat yang temkur pada perlakuan ini mencapai 120
ppm. Tanah lapisan b a d yang berkadar S lebrh bnggr, semua perlakuan
yang
&ternplan pada
lapisan bawah rnenyebabh
peningkatan
transformasi sulfur tanah lapisan bahwa sebanyak 1,5 kali lipat dari lapisan
atas.
maksimum sulfatnya masing-masing sbanyak 416,6 dan 3222 pprn S
Pemberian kapur sampai 1,0 & menurunkan erapan maksimum fosfat
pada lapisan atas clan bawah masing-masing menjadi 1 250 dan I I 1 1,l ppm
P, sedafigkan erapan maksimurn sulfat masing-masing menjadi 2 12,8 dan
18 1,8 pprn S. Dengan asumi bahwa konsentrasi kritis fosfat dan sulfkt
untuk pertumbuhan tanaman di dab larutan tanah masmg-masing 0,02
pprn P dan 5- 10 pprn S, maka dilihat dari kurva hubungan antara P dan S-
ditarnb*
dengan konsentrasi P dan S di d d m lamtan tanah, untuk
mencaw konsentrasi tersebut diperlukan penambahan fosfat dan sulfat
masing-masing sebanyak 100 pprn P dan 97 pprn S.
Tejadi interaksi sinergis yang lemah antara sulfat clan fosfat pada
semua metode pernberian sdfat
dan fosfat yang diuji. Dengan rnengukur
konsentrasi sulfat dan fosfat pada larutan tanah, diketahui bahm sulfit
tertinggi diperoleh pada rnetode pembenan fosfat 1 minggu lebih awal d m
pembenan sulfur (A). Sedangkan fosfat temggi diperoleh pa&
metode
pemberian fosfat bersamaan dengan sulfur (B).
Pengapuran sampai dengan 1,O Aha cenderung meninghtkan
pertumbuhan kacmg tanah, sedangkan pemberian sulfht dan fosfit
meningkatkan pertumbuhan k
g tanah secara nyata. Hal hi krlthat d m
tinggi tanaman kacang tanah pada perlakuan kapur 1,O & kombinasi
dengan pemberian sulfat dan fosfat wing-masing 7,5 ppm S d m 0,03 pprn