P E N G A R U H B E R B A G A I BAHAN A M E L I O R A N T E R H A D A P
pHo. R E T E N S I P DAN K T K PADA B E B E R A P A ANDISOL
DI JAWA B A R A T
Oleh: Dr. Rina Devnita, I r . , M.S., M.Sc. N I P . 1 9 6 3 1 2 2 2 1 9 8 9 0 3 2 0 0 1 N I D N . 0 0 2 2 1 9 6 3 0 9 F A K U L T A S P E R T A N I A N U N I V E R S I T A S P A D J A D J A R A N 2010P E N G A R U H B E R B A G A I BAHAN A M E L I O R A N TERHADAP
pHo. R E T E N S I P DAN K T K PADA B E B E R A P A ANDISOL
DI JAWA B A R A T
D r . R i n a D e v n i t a , I r . , M . S . , M . S c . N I P . 1 9 6 3 1 2 2 2 1 9 8 9 0 3 2 0 0 1 N I D N . 0 0 2 2 1 9 6 3 0 9 F A K U L T A S P E R T A N I A N U N I V E R S I T A S P A D J A D J A R A N K e t u a J u r u s a n I l m u T a n a h d a n S u m b e r d a y a L a h a n F a k u l t a s P e r t a n i a n U n i v e r s i t a s P a d j a d j a r a n O l e h : B a n d u n g , F e b r u a r i 2 0 1 0 M e n g e t a h u i : P e n u l i s D r . R a c h m a t H a r r y a n t o . I r . , M . S . D r . R i n a D e v n i t a , I r . , M . S . , M . S c . N I P . 1 9 6 3 1 2 2 2 1 9 8 9 0 3 2 0 0 1 N I P . 1 9 5 7 0 3 1 1 1 9 8 6 0 1 1 0 0 1P e n e l i t i a n u n t u k m e n g e t a h u i p e n g a r u h b e r b a g a i b a h a n a m e l i o r a n t e r h a d a p p H o , r e t e n s i P d a n K T K p a d a b e b e r a p a A n d i s o l d i J a w a B a r a t d i l a k u k a n d a l a m d u a t a h a p y a i t u d i l a p a n g a n u n t u k s u r v e y d a n p e n g a m b i l a n s a m p e l t a n a h s e r t a d i l a b o r a t o r i u m u n t u k a n a l i s i s p e r u b a h a n s i f a t t a n a h s e t e l a h d i b e r i a m e l i o r a n . A m e l i o r a s i A n d i s o l m e n c a k u p i n k u b a s i t a n a h d e n g a n a m e l i o r a n t e r a k b a j a , b a t u a n f o s f a t d a n b o k a s h i s e k a m p a d i s e l a m a e m p a t b u l a n u n t u k m e l i h a t p e r u b a h a n p H o , r e t e n s i P d a n K T K s e t e l a h d i b e r i a m e l i o r a n . H a s i l a n a l i s i s m e n u n j u k k a n p e m b e r i a n a m e l i o r a n t e r a k b a j a , b a t u a n f o s f a t d a n b o k a s h i s e k a m p a d i p a d a A n d i s o l d i J a w a B a r a t b e r p o t e n s i u n t u k m e n u r u n k a n p H o d a n m e n i n g k a t k a n K T K . A m e l i o r a n j u g a d a p a t m e n u r u n k a n r e t e n s i P A n d i s o l , n a m u n t i d a k d a p a t m e m b u a t n y a l e b i h k e c i l d a r i 8 5 %. n i
" P e n g a r u h B e r b a g a i B a h a n A m e l i o r a n t e r h a d a p p H o , R e t e n s i P d a n K T K p a d a B e b e r a p a A n d i s o l d i J a w a B a r a t " . P e n e l i t i a n i n i b e r t u j u a n u n t u k m e n g e t a h u i m a n a j e m e n y a n g t e p a t p a d a A n d i s o l s e s u a i d e n g a n k a r a k t e r i s t i k t a n a h n y a y a n g b e r m u a t a n v a r i a b e l d a n m e m p u n y a i r e t e n s i P y a n g t i n g g i P e n u l i s m e n g u c a p k a n t e r i m a k a s i h k e p a d a b e r b a g a i p i h a k y a n g t e l a h m e m b a n t u p e l a k s a n a a n p e n e l i t i a n i n i m u l a i d a r i p e l a k s a n a a n p e n e l i t i a n d i l a p a n g a n , a n a l i s i s d i l a b o r a t o r i u m h i n g g a t e r w u j u d n y a l a p o r a n h a s i l p e n e l i t i a n i n i . P a d a k e s e m p a t a n i n i p e n u l i s m e n g u c a p k a n t e r i m a k a s i h k e p a d a I r . R i d h a H u d a y a , I r . , M . S . , a t a s b a n t u a n n y a s e l a m a d i l a p a n g a n ; P r o f . E . V a n R a n s t d a r i G h e n t U n i v e r s i t y B e l g i u m a t a s i z i n n y a r n e l a k u k a n a n a l i s i s p H o d a n r e t e n s i P d i L a b o r a t o r i u m P h y s i c a l a n d L a n d R e s o u r c e ; A d e S e t i a w a n , I r . M . P . a t a s b a n t u a n n y a u n t u k a n a l i s i s d a t a ; s e r t a A a n g N u r B a s k o r o , A n d r i R e s t i a n d i d a n R a d i t a t a s b a n t u a n n y a m e l a k u k a n a n a l i s i s d i L a b o r a t o r i u m K i m i a d a n K e s u b u r a n T a n a h F a k u l t a s P e r t a n i a n U n i v e r s i t a s P a d j a d j a r a n . P e n u l i s b e r h a r a p l a p o r a n h a s i l p e n e l i t i a n i n i d a p a t b e r m a n f a a t u n t u k p e n g e m b a n g a n I l m u P e r t a n i a n t e r u t a m a I l m u T a n a h . B a n d u n g , F e b r u a r i 2 0 1 0 P e n u l i s , R i n a D e v n i t a iv
H a l a m a n A B S T R A K i i i K A T A P E N G A N T A R i v D A F T A R I S I V D A F T A R T A B E L ^ • v i i D A F T A R G A M B A R v i i i D A F T A R L A M P I R A N i x B A B I P E N D A H U L U A N 1 1.1 L a t a r B e l a k a n g L 1.2 R u m u s a n M a s a l a h 3 1.3 T u j u a n P e n e l i t i a n ; 3 B A B I I K A J I A N P U S T A K A , K E R A N G K A P E M I K I R A N , D A N H I P O T E S I S 4 2 . 1 K a j i a n P u s t a k a 4 2 . 1 . 1 K e t e r s e d i a a n F o s f o r p a d a A n d i s o l 4 2 . 1 . 2 M e n u r u n k a n p H d e n g a n S i l i k a t , F o s f a t , B a h a n O r g a n i k 6 2 . 2 K e r a n g k a P e m i k i r a n 7 2 . 3 H i p o t e s i s 1 0 B A B I I I B A H A N D A N M E T O D E P E N E L I T I A N 1 1 3 . 1 W a k t u d a n T e m p a t P e n e l i t i a n 1 1 3 . 2 B a h a n d a n A l a t 1 1 3 . 3 M e t o d e P e n e l i t i a n 1 2 3 . 3 . 1 P e n e l i t i a n L a p a n g a n 1 3 3 . 3 . 2 A n a l i s i s L a b o r a t o r i u m 1 4 B A B I V H A S I L D A N P E M B A H A S A N 1 9 4 . 1 D e s k r i p s i U m u m D a e r a h P e n e l i t i a n 1 9 4 . 1 . 1 L o k a s i D a e r a h P e n e l i t i a n 1 9 4 . 1 . 2 T o p o g r a f i D a e r a h P e n e l i t i a n 2 0 4 . 1 . 3 G e o l o g i D a e r a h P e n e l i t i a n 2 0 4 . 1 . 4 P e n g g u n a a n L a h a n d a n V e g e t a s i 2 1 4 . 1 . 5 I k l i m 2 1 V
B A B V K E S I M P U L A N D A N S A R A N 3 8
5 . 1 K e s i m p u l a n 3 8 5 . 2 S a r a n 3 8 D A F T A R P U S T A K A 3 9
H a l a m a n T a b e l 1 . K o m b i n a s i P e r l a k u a n T a n a h d a n A m e l i o r a n 1 6 T a b e l 2 . A n a l i s i s s i d i k r a g a m p e r c o b a a n i n k u b a s i d e n g a n a m e l i o r a n 1 7 T a b e l 3 . L o k a s i , s u m b e r e r u p s i , s i f a t b a h a n i n d u k d a n u m u r g e o l o g i b a h a n i n d u k A n d i s o l d a e r a h p e n e l i t i a n 1 9 T a b e l 4 . D a t a h a r i h u j a n , c u r a h h u j a n , s u h u u d a r a d a n s u h u t a n a h p a d a l o k a s i p e n e l i t i a n 2 2 vii
H a l a m a n G a m b a r 1 . V e g e t a s i d a n P e n g g u n a a n L a h a n D a e r a h P e n e l i t i a n ( a ) A n d i s o l h a s i l e r u p s i G . T a n g k u b a n P a r a h u ( T P R ) ( b ) A n d i s o l h a s i l e r u p s i G . P a t u h a ( P T H ) , ( c ) A n d i s o l h a s i l e r u p s i G . T i l u ( T L U ) 1 3 G a m b a r 2 . P e r u b a h a n p H o s e t e l a h i n k u b a s i p a d a b u l a n k e 2 , 3 d a n 4 t a n a h T P R '. 2 4 G a m b a r 3 . P e r u b a h a n p H o s e t e l a h i n k u b a s i p a d a b u l a n k e 2 , 3 d a n 4 t a n a h P T H 2 5 G a m b a r 4 . P e r u b a h a n p H o s e t e l a h i n k u b a s i p a d a b u l a n k e 2 , 3 d a n 4 t a n a h T L U 2 6 G a m b a r 5 . S k e m a p e n u r u n a n p H o m e l a l u i j e r a p a n p r o t o n p e r m u k a a n o k s i d a F e a k i b a t f i k s a s i f o s f a t ( V a n R a n s t , 2 0 0 6 ) 2 7 G a m b a r 6 . P e r u b a h a n r e t e n s i P s e t e l a h i n k u b a s i p a d a b u l a n k e 2 , 3 d a n 4 t a n a h T P R ...29 G a m b a r 7 . P e r u b a h a n r e t e n s i P s e t e l a h i n k u b a s i p a d a b u l a n k e 2 , 3 d a n 4 t a n a h P T H 3 0 G a m b a r 8 . P e r u b a h a n r e t e n s i P s e t e l a h i n k u b a s i p a d a b u l a n k e 2 , 3 d a n 4 t a n a h T L U 3 0 G a m b a r 9 . P e r u b a h a n K T K s e t e l a h i n k u b a s i p a d a b u l a n k e 2 , 3 d a n 4 t a n a h T P R 3 5 G a m b a r 1 0 . P e r u b a h a n K T K s e t e l a h i n k u b a s i p a d a b u l a n k e 2 , 3 d a n 4 t a n a h P T H 3 5 G a m b a r 1 1 . P e r u b a h a n K T K s e t e l a h i n k u b a s i p a d a b u l a n k e 2 , 3 d a n 4 t a n a h T L U 3 6 v i i i
H a l a m a n L a m p i r a n 1 . H a s i l a n a l i s i s a m e l i o r a n t e r a k b a j a 4 5 L a m p i r a n 2 . H a s i l a n a l i s i s a m e l i o r a n b a t u a n f o s f a t 4 5 L a m p i r a n 3 . P r o s e d u r p e m b u a t a n b o k a s h i d a n h a s i l a n a l i s i s b o k a s h i 4 6 L a m p i r a n 4 . H a s i l A n a l i s i s B o k a s h i S e k a m P a d i 4 7 L a m p i r a n 5 . H a s i l a n a l i s i s p H o , r e t e n s i P ( % ) , d a n K T K ( c m o l k g ' ' ) p a d a b u l a n k e - 2 , 3 , d a n 4 i n k u b a s i , 4 8 L a m p i r a n 6 . A n a l i s i s v a r i a n s p H o , r e t e n s i P , d a n K T K p a d a b u l a n k e - 2 , 3 , d a n 4 i n k u b a s i . . . 4 9 ix
L I L a t a r Belakang T a n a h y a n g b e r k e m b a n g d a r i h a s i l e r u p s i g u n u n g a p i m e m p u n y a i m i n e r a l l i a t y a n g k h a s b e r u p a m i n e r a l o r d o k i s a r a n p e n d e k s e p e r t i a l o f a n , i m o g o l i t d a n f e r i h i d i r i t ( C h i l d s et al, 1 9 9 1 ) . M i n e r a l t e r s e b u t b e r m u a t a n v a r i a b e l y a n g m u a t a n k o l o i d n y a t e r g a n t u n g p a d a p H t a n a h ( U e h a r a d a n G i l l m a n , 1 9 8 1 ) . T a n a h b e r m u a t a n v a r i a b e l m e m p u n y a i p H o t i n g g i d a n k a p a s i t a s t u k a r k a t i o n ( K T K ) r e n d a h s e h i n g g a k e m a m p u a n t a n a h m e n a h a n k a t i o n r e n d a h . M i n e r a l i n i j u g a m e m p u n y a i r e t e n s i P y a n g t i n g g i s e h i n g g a k e t e r s e d i a a n P m e n j a d i m a s a l a h u t a m a ( V a n R a n s t a / . , 1 9 9 3 ) . I n d o n e s i a m e m i l i k i b a n y a k g u n u n g a p i d a n t a n a h y a n g b e r k e m b a n g d a r i a b u g u n u n g a p i . T a k s o n o m i T a n a h m e n g e l o m p o k k a n t a n a h i n i d a l a m o r d o
A n d i s o l {Soil Survey Staff, 1 9 9 0 ) . L u a s A n d s o l m e n c a p a i 5 . 8 3 6 j u t a h a a t a u 3 , 4 % l u a s I n d o n e s i a ( P u s l i t b a n g t a n a k , 2 0 0 1 ) . A n d i s o l d i J a w a B a r a t d a p a t d i j u m p a i d i b e r b a g a i w i l a y a h a n t a r a l a i n d i s e k i t a r G u n u n g T a n g k u b a n P a r a h u , G u n u n g P a t u h a , G u n u n g T i l u d a n d a e r a h b e r g u n u n g a p i l a i n n y a ( A r i f m , 1 9 9 4 ) . A n d i s o l m e r u p a k a n t a n a h y a n g p r o d u k t i f , a k a n t e t a p i t i d a k b e r a r t i t a n a h i n i t i d a k m e m p u n y a i m a s a l a h . A l o f a n s e b a g a i k o m p o n e n p a l i n g a k t i f d e n g a n s t r u k t u r b e r l u b a n g - l u b a n g d a n m u a t a n n y a y a n g v a r i a b e l s a n g a t k u a t m e n a h a n f o s f a t ( F a r m e r et al, 1 9 9 1 ) , s e h i n g g a m e n y e b a b k a n k e t e r s e d i a a n P r e n d a h d a n P y a n g b e r a s a l d a r i p u p u k d e n g a n c e p a t b e r k u r a n g . H a n y a s e k i t a r 1 0 % p u p u k P 1
y a n g d i b e r i k a n d a p a t d i g u n a k a n o l e h t a n a m a n ( E g a w a , 1 9 8 4 ) . S e l a i n i t u a l o f a n m e m p u n y a i p H o t i n g g i d a n K T K r e n d a h s e h i n g g a t e r j a d i k e h i l a n g a n k a t i o n y a n g b e s a r . M a s a l a h y a n g d i j u m p a i p a d a A n d i s o l m e n y e b a b k a n m a n a j e m e n t a n a h i n i d i a r a h k a n p a d a u s a h a u n t u k m e n g u r a n g i r e t e n s i P d a n m e n i n g k a t k a n K T K . R e t e n s i P d a p a t d i k u r a n g i d e n g a n m e m b l o k m u a t a n p o s i t i f t a n a h d e n g a n a n i o n b e r v a l e n s i t i n g g i s e p e r t i s i l i k a t , f o s f a t d a n b a h a n o r g a n i k ( Q a f u k u et al, 2 0 0 4 ) . K T K d a p a t d i t i n g k a t k a n d e n g a n m e n i n g k a t k a n m u a t a n p e r m u k a a n n e g a t i f ( V a n R a n s t , 2 0 0 6 ) . H a l i n i d a p a t d i c a p a i d e n g a n m e n i n g k a t k a n p H , m e n i n g k a t k a n k o n s e n t r a s i e l e k t r o l i t t a n a h a t a u m e n u r u n k a n p H o ( B a e r t , 1 9 9 5 ) . N i l a i p H o j u g a d a p a t d i t u r u n k a n d e n g a n p e m b e r i a n a m e l i o r a n b e r u p a s i l i k a t , f o s f a t d a n b a h a n o r g a n i k ( V a n R a n s t et al, 1 9 9 3 ) . P e n e l i t i a n y a n g b e r t u j u a n u n t u k m e m p e r b a i k i k a r a k t e r i s t i k A n d i s o l d e n g a n m e n u r u n k a n r e t e n s i P b e l u m b a n y a k d i l a k u k a n d i I n d o n e s i a , s e m e n t a r a a m e l i o r a n u n t u k m e m p e r b a i k i k a r a k t e r i s t i k t e r s e b u t d a p a t d i p e r o l e h d a r i b e r b a g a i s u m b e r . S i l i k a t , f o s f a t d a n b a h a n o r g a n i k d a p a t d i p e r o l e h a n t a r a l a i n d a r i t e r a k b a j a , b a t u a n f o s f a t d a n b o k a s h i s e k a m p a d i . B e r d a s a r k a n k e b u t u h a n u n t u k m e m p e r b a i k i k a r a k t e r i s t i k A n d i s o l d e n g a n m a n a j e m e n y a n g s e s u a i m e l a l u i p e n u r u n a n r e t e n s i P d a n p e n i n g k a t a n K T K , m a k a p e n e l i t i a n i n i d i l a k u k a n d e n g a n m e n g g u n a k a n t e r a k b a j a , b a t u a n f o s f a t d a n b o k a s h i s e k a m p a d i s e r t a m e l i h a t r e s p o n s n y a t e r h a d a p t a n a m a n j a g u n g .
1.2 Rumusan Masaiah B e r d a s a r k a n h a l - h a l y a n g t e l a h d i u r a i k a n , m a k a r u m u s a n m a s a l a h n y a a d a l a h s e b a g a i b e r i k u t : 1 ) A p a k a h a m e l i o r a n t e r a k b a j a , b a t u a n f o s f a t d a n b o k a s h i s e k a m p a d i d a p a t m e n u r u n k a n p H o ? 2 ) A p a k a h a m e l i o r a n l e r a k b a j a , b a t u a n f o s f a t d a n b o k a s h i s e k a m p a d i d a p a t m e n u r u n k a n r e t e n s i P ? 3 ) A p a k a h a m e l i o r a n t e r a k b a j a , b a t u a n f o s f a t d a n b o k a s h i s e k a m p a d i d a p a t m e n i n g k a t k a n K T K ? 1.3 T u j u a n Penelitian M e n g e t a h u i p e n g a r u h t e r a k b a j a , b a t u a n f o s f a t d a n k o m p o s s e k a m p a d i s e b a g a i a m e l i o r a n d a l a m m e n u r u n k a n p H o , m e n u r u n k a n r e t e n s i f o s f a t , d a n m e n i n g k a t k a n K T K A n d i s o l .
2.1 K a j i a n Pustaka
2.1.1 Ketersediaan Fosfor pada Andisol
K e t e r s e d i a a n P y a n g r e n d a h m e r u p a k a n m a s a l a h u t a m a A n d i s o l k a r e n a r e t e n s i P t a n a h i n i s a n g a t t i n g g i ( V a n R a n s t et al, 1 9 9 3 ) . H a l i n i b e r k a i t a n d e n g a n k e b e r a d a a n m i n e r a l o r d o k i s a r a n p e n d e k s e p e r t i a l o f a n d a n i m o g o l i t y a n g m e m p u n y a i s e n y a w a a l u m i n i u m d a n b e s i a m o r f u s p a d a s t r u k t u r n y a y a n g b e r e a k s i d e n g a n P d a n m e n y e b a b k a n r e t e n s i t e r s e b u t ( B e c k et al, 1 9 9 9 ) . B a h k a n p a d a A n d i s o l y a n g m a s i h m u d a p u n r e t e n s i P d a p a t l e b i h b e s a r d a r i 2 5 % ( S h o j i et al, 1 9 9 3 ) . R e t e n s i P d i g u n a k a n u n t u k m e m b e d a k a n A n d i s o l d a r i t a n a h l a i n n y a . E a t a s a n 8 5 % d i g u n a k a n u n t u k m e m b e d a k a n t a n a h A n d i s o l d e n g a n b u k a n
A n d i s o l {Soil Survey Staff, 2 0 0 6 ) .
M a s a l a h P p a d a A n d i s o l t i d a k s a j a k a r e n a k e t i d a k t e r s e d i a a n n y a , t e t a p i j u g a k a r e n a s e j u m l a h b e s a r P y a n g h a r u s d i t a m b a h k a n u n t u k m e n g i m b a n g i r e t e n s i n y a ( I m a i et al, 1 9 8 1 ; W a d a , 1 9 8 5 ) . S e b e n a m y a k a n d u n g a n P t o t a l t a n a h m u n g k i n c u k u p t i n g g i , a k a n t e t a p i P t e r s e b u t b e r a d a d a l a m b e n t u k y a n g t i d a k t e r s e d i a u n t u k t a n a m a n . P u p u k P y a n g d i t a m b a h k a n d a l a m b e n t u k y a n g l a r u t a k a n s e g e r a d i i k a t o l e h m i n e r a l o r d o k i s a r a n p e n d e k . R e t e n s i P b a h k a n b i s a m e n c a p a i 9 9 % , y a n g m e n u n j u k k a n h a m p i r s e m u a P y a n g d i b e r i k a n k e d a l a m t a n a h d a p a t d i i k a t ( B a l k o v i c , 2 0 0 2 ) . 4
E f e k t i v i t a s p e m u p u k a n P s a n g a t t e r g a n t u n g p a u a k e b e r a d a a n P d a l a m l a r u t a n t a n a h . U e h a r a d a n G i l l m a n ( 1 9 8 1 ) , m e n j e l a s k a n b a h w a j i k a t a n a m a n m e n y e r a p P d a r i l a r u t a n t a n a h , l a r u t a n t a n a h a k a n s e g e r a m e n a m b a h l a g i k e t e r s e d i a a n P t e r s e b u t . P e n a m b a h a n k e m b a l i i n i h a n y a a k a n t e r j a d i d a l a m j u m l a h y a n g c u k u p j i k a t a n a h m e m p u n y a i k a p a s i t a s y a n g b e s a r u n t u k m e n j e r a p d a n m e l e p a s k a n P . O l e h s e b a b i t u , m e s k i p u n t a n a h y a n g k a y a a k a n m i n e r a l o r d o k i s a r a n p e n d e k m e m b u t u h k a n P l e b i h b a n y a k u n t u k m e n c a p a i k e t e r s e d i a a n P d a l a m j u m l a h t e r t e n t u , t a n a h i n i j u g a m e m p u n y a i k o m p e n s a s i b e r u p a k e m a m p u a n u n t u k m e n y e d i a k a n P k e m b a l i k e d a l a m l a r u t a n t a n a h b e g i t u P d i s e r a p o l e h t a n a m a n . A n d i s o l m e m a n g m e n j e r a p s e j u m l a h b e s a r P d a l a m w a k t u s i n g k a t , a k a n t e t a p i m e l e p a s k a n k a n n y a k e m b a l i s e c a r a p e r l a h a n . D e n g a n d e m i k i a n b i a y a a w a l y a n g t i n g g i u n t u k p e m u p u k a n P d a p a t d i a n g g a p s e b a g a i i n v e s t a s i k a r e n a d a p a t t e r b a y a r d e n g a n k e t e r s e d i a a n P u n t u k b e b e r a p a w a k t u k e m u d i a n ( B e c k et ai, 1 9 9 9 ) . P e n g e l o l a a n y a n g t e p a t d i b u t u h k a n u n t u k mengatasi m a s a l a h r e t e n s i P y a n g t i n g g i a g a r m e n g u r a n g i b i a y a p e m u p u k a n P . H a l y a n g d a p a t d i l a k u k a n a d a l a h m e m i n i m a l k a n r e t e n s i f o s f a t , m e m b e r i k a n s u m b e r P y a n g m u r a h s e p e r t i b a t u a n f o s f a t , m e m b e r i k a n t a k a r a n s e r t a p e n e m p a t a n p u p u k y a n g t e p a t d a n m e m b e r i k a n e f e k j a n g k a p a n j a n g , m e m a n f a a t k a n s i s a t a n a m a n s e r t a m e m i l i h s p e s i e s d a n v a r i t a s t a n a m a n y a n g t e p a t y a n g t o l e r a n t e r h a d a p k e t e r s e d i a n P r e n d a h ( V a n R a n s t , 2 0 0 6 ) .
2.1.2 Menurunkan retensi P dengan Silikat, Fosfat dan Bahan Organik F o s f a t d a p a t s e c a r a k h u s u s d i j e r a p p a d a p e r m u k a a n o k s i d a y a n g m u a t a n p e r m u k a a n n y a n o l , b a h k a n n e g a t i f ( U e h a r a d a n G i l l m a n , 1 9 8 1 ) . S a a t j e r a p a n f o s f a t t e r j a d i , t e r j a d i p u l a k o o r d i n a s i a n i o n d e n g a n p e r m u k a a n i o n l o g a m . M o l e k u l H 2 O d a n i o n O H y a n g b e r p i n d a h k e i o n l o g a m d i g a n t i k a n o l e h i o n f o s f a t H 2 P 0 4 ' ( V a n R a n s t , 1 9 9 4 ) . P e n g g a n t i a n m o l e k u l H 2 O o l e h i o n f o s f a t m e n g h a s i l k a n p e n g u r a n g a n m u a t a n p o s i t i f D e n g a n d e m i k i a n t e r j a d i p e n i n g k a t a n m u a t a n n e g a t i f d a n p e n a m b a h a n k a p a s i t a s t u k a r k a t i o n s e r t a p e n u r u n a n p H o ( H i n g s t o n et al, 1 9 7 2 ) . W a r m d a n U e h a r a ( 1 9 7 8 ) , m e n u n j u k k a n b a h w a p e n i n g k a t a n j u m l a h f o s f a t m e n y e b a b k a n p e n u r u n a n p H o s e c a r a l i n i e r d a n s e i r i n g d e n g a n i t u t e r j a d i p e n i n g k a t a n m u a t a n n e g a t i f P e m b e r i a n 1 5 0 0 p p m p u p u k P y a n g m e n g a n d u n g C a d a p a t m e n u r u n k a n p H o d a r i 5 . 0 m e n j a d i l e b i h k e c i l d a r i 3 . 5 . A n i o n s i l i k a t m a m p u s e c a r a s p e s i f i k t e r j e r a p p a d a p e r m . u k a a n o k s i d a s e h i n g g a m e n u r u n k a n n i l a i p H o ( B a e r t , 1 9 9 5 ; F i a n t i s , 2 0 0 0 ) . G i l l m . a n ( 1 9 8 5 ) m e n y a t a k a n b a h w a p H o j u g a d a p a t d i t u r u n k a n 1 u n i t d e n g a n p e n a m b a h a n f o s f a t s e b a n y a k 1 0 0 p p m P a t a u d e n g a n m e n i n g k a t k a n C - o r g a n i k t a n a h s e b e s a r I %. A n i o n s i l i k a t y a n g t e r b e n t u k m e l a l u i h i d r o l i s i s s e n y a w a s i l i k a t b e r k o m p e t i s i d e n g a n i o n f o s f a t p a d a t a p a k j e r a p a n . A d s o r p s i i o n s i l i k a t t e r s e b u t a k a n m e n g h a s i l k a n p e n u r u n a n p H o ( B o n i a o , 2 0 0 0 ; F i a n t i s , 2 0 0 0 ) . S e l a i n i t u h i d r o l i s i s k e l o m p o k S i O m e l e p a s k a n s e j u m l a h C a , N a , M g d a n K k e d a l a m t a n a h ( M i t c h e l l , 2 0 0 4 ) , d a n m e n y e b a b k a n p e n i n g k a t a n p H ( T i s d a l e et al, 1 9 9 3 ; V a n R a n s t , 1 9 9 5 ) , s e p e r t i t e r l i h a t p a d a r e a k s i b e r i k u t y a n g m e n g h a s i l k a n i o n h i d r o k s i l y a n g d a p a t m e n y e b a b k a n m e n i n g k a t n y a p H :
S i 0 4 " ' ' + H 2 O S i 0 3 ( 0 H ) - ' + O H -S i 0 3 ( 0 H ) - ^ + H 2 O S i O ? ( O H) 2 " ^ + O H " S i 0 2 ( O H) 2 - ' + H 2 O ^ S i O ( 0 H) 3 " + O H -S i O ( O H) 3 - + H 2 O S i O ( 0 H) 4 + O K " B a h a n o r g a n i l c m e m p u n y a i p H o y a n g c u k u p r e n d a h y a i t u s e k i t a r 4 ( B a e n , 1 9 9 5 ) . J i k a p H o t a n a h l e b i h b e s a r d a r i 4 , b a h a n o r g a n i k a k a n m e m b e r i k a n k o n t r i b u s i y a n g c u k u p b e s a r t e r h a d a p K T K . T a n a h b e r m u a t a n v a r i a b e l y a n g d i t a m b a h k a n d e n g a n b a h a n o r g a n i k d a l a m j u m l a h b e s a r , a k a n m e n g a l a m i p e n u r u n a n p H o m e l a l u i j e r a p a n a n i o n o r g a n i k y a n g m e n u t u p i s c b a g i a n p e r m u k a a n p o s i t i f n y a s e h i n g g a a k a n l e b i h m e n i n g k a t k a n m u a t a n n e g a t i f ( G i l l m a n , 1 9 8 5 ) . 2.2 K e r a n g k a Pemikiran T a n a h a b u g u n u n g a p i m e m p u n y a i m u a t a n v a r i a b e l t i n g g i y a n g b e r a s a l d a r i o k s i d a b e s i d a n a l u m i n i u m . O k s i d a - o k s i d a i n i m e m p u n y a i p e r m u k a a n r e a k t i f a m f o t e r y a n g b e r m u a t a n p o s i t i f p a d a k o n d i s i m a s a m d a n b e r m u a t a n n e g a t i f p a d a k o n d i s i b a s a . G o e t i t m e m p u n y a i p H o a n t a r a 7 . 5 - 9 . 4 d a n h e m a t i t a n t a r a 7 - 9 . 2 ( K o s m u l s k ' , 2 0 0 2 ) . O k s i d a - o k s i d a l a i n m e m p u n y a i p H o a n t a r a 7 - 9 d a n s a n g a t t e r g a n t u n g p a d a p H t a n a h d a n k e k u a t a n i o n ( G i l l m a n , 1 9 8 1 ) . T e r a k b a j a {slag steel) m e r u p a k a n h a s i l s a m p i n g a n d a r i p r o s e s p e m b u a t a n b e s i b a j a y a n g d i o l a h d a r i b i j i h b e s i ( M i t c h e l l , 2 0 0 4 ) . K o m p o s i s i t e r a k b a j a b e r v a r i a s i a n t a r a s a t u p a b r i k d a n p a b r i k l a i n n y a , y a n g t e r g a n t u n g p a d a s u m b e r b e s i y a n g d i g u n a k a n d a n p r o s e s y a n g d i l a k u k a n . S e c a r a u m u m t e r a k b a j a m e n g a n d u n g k a l s i u m s i l i k o n f o s f a t , b e s i s i l i k o - f o s f a t , s e j u m l a h F e , S i , M g d a n
M n . S e l a i n i t u t e r a k b a j a j u g a d a p a t m e n g a n d u n g C u , M o , Z n , C o d a l a m j u m l a h y a n g l e b i h s e d i k i t ( K a l y o n c u , 1 9 9 8 ) . H a s i l s a m p i n g a n i n d u s t r i l o g a m i n i m e m p u n y a i b e r b a g a i k e g u n a a n a n t a r a l a i n u n t u k p e n g u a t k o n s t r u k s i j a l a n d a n b a n g u n a n l a i n n y a s e r t a u n t u k p e r t a n i a n ( E m e r y , 1 9 8 2 ; M i t c h e l l , 2 0 0 4 ) . T e r a k b a j a t e l a h l a m a d i g u n a k a n u n t u k u s a h a p e r t a n i a n , b a i k s e b a g a i s u m b e r P , s u m b e r S i d a n k a p u r ( R e x , 2 0 0 2 ) . B a h k a n s e b e l u m P e r a n g D u n i a 11 t e r a k b a j a m e n y e d i a k a n s e k i t a r 7 0 % k e b u t u h a n p u p u k f o s f a t d i J e r m a n , B e i g i a , P e r a n c i s d a n I n g g r i s R a y a ( R e x , 2 0 0 4 ) . P a d a t a h u n 1 9 7 0 / 1 9 7 1 s e k i t a r s e p e r t i g a d a r i p u p u k P y a n g d i g u n a k a n d i J e r m a n b e r a s a l d a r i t e r a k b a j a . F u n g s i t e r a k s e b a g a i k a p u r p e r t a n i a n b a i k u n t u k m e n i n g k a t k a n p H m a u p u n u n t u k m e n i a d a k a n k e r a c u n a n A l t e l a h t e r u j i p a d a b e r b a g a i p e n e l i t i a n ( E v a n s d a n K a m p r a t h , 1 9 7 0 ) . W i j a y a ( 2 0 0 5 ) , m e n y a t a k a n b a h w a t e r a k b a j a d a p a t m e n i n g k a t k a n p H t a n a h d a n m e n u r u n k a n A l - d d . D a y a n e t r a l i t a s t e r a k b a j a d a p a t m e n c a p a i 7 5 - 9 0 % ( T i s d a l e et al, 1 9 9 3 ) , m e s k i p u n e f e k t i v i t a s t e r a k b a j a s e b a g a i p u p u k d a n k a p u r s a n g a t t e r g a n t u n g p a d a t a n a h d a n t a n a m a n y a n g d i g u n a k a n ( S a n c h e z d a n U e h a r a , 1 9 8 0 ) . T e r a k b a j a d a p a t m e n i n g k a t k a n p r o d u k s i r u m p u t d i p a d a n g g e m b a l a t e r u t a m a p a d a t a n a h y a n g k a n d u n g a n S i - n y a r e n d a h ( P i n t o et al, 1 9 9 3 ) . T e r a k b a j a j u g a d i l a p o r k a n d a p a t m e n i n g k a t k a n p r o d u k s i k e n t a n g , j a g u n g , w o r t e l , s e l a d a , b r o k o l i , d l l ( Y a o , 2 0 0 1 ) . S e b a g a i a m e l i o r a n , i o n s i l i k a t b e r v a l e n s i t i n g g i y a n g t e r d a p a t p a d a t e r a k b a j a m a m p u m e m b l o k m u a t a n p o s i t i f t a n a h s e h i n g g a d a p a t m e n u r u n k a n p H o ( V a n R a n s t , 2 0 0 6 ) . P e n g g u n a a n t e r a k b a j a s e b a g a i a m e l i o r a n y a n g m e n u r u n k a n p H o t a n a h b e l u m b a n y a k d i l a p o r k a n . A k a n t e t a p i p e n g g u n a a n k a l s i u m s i l i k a t
( C a S i O s ) u n t u k m e n u r u n k a n p H o t e l a h d i l a p o r k a n o l e h F i a n t i s ( 2 0 0 0 ) d a n B o n i a o ( 2 0 0 0 ) . P e m b e r i a n 1 2 0 t h a ' C a S i O s p a d a A n d i s o l d a r i S u m a t e r a B a r a t d a n p e m b e r i a n 1 0 % C a S i O a p a d a t a n a h a b u g u n u n g a p i d a r i P u l a u C a m i g u i n , F i l i p i n a d a p a t m e n u r u n k a n p H o . K a n d u n g a n k a l s i u m d a n s i l i k a t y a n g c u k u p t i n g g i p a d a t e r a k b a j a d i h a r a p k a n d a p a t b e r f u n g s i s e p e r t i C a S i O s d a l a m m e n u r u n k a n p H o t a n a h . S e l a i n t e r a k b a j a , b a t u a n f o s f a t d a p a t b e r f u n g s i s e b a g a i a m e l i o r a n k a r e n a m u a t a n n e g a t i f i o n f o s f a t d a p a t m e m b l o k m u a t a n p o s i t i f t a n a h b e r m u a t a n v a r i a b e l . B a t u a n f o s f a t y a n g d i h a l u s k a n d e n g a n d o s i s 3 t o n h a " ' d a p a t m e m p e r b a i k i k a r a k t e r i s t i k t a n a h m a s a m m e l a l u i s u m b a n g a n g u g u s r e a k t i f i o n f o s f a t n y a ( T i s d a l e a / . , 1 9 9 3 ) . B a h a n o r g a n i k m e m p u n y a i p H o r e n d a h ( < 4 ) d a n m e m p u n y a i k o n t r i b u s i t e r h a d a p p H o t a n a h ( G i l l m a n , 1 9 8 5 ) . J i k a b a h a n o r g a n i k d i t a m b a h k a n p a d a t a n a h b e r m u a t a n v a r i a b e l , a n i o n o r g a n i k a k a n d i j e r a p p a d a p e r m u k a a n p a r t i k e l s e h i n g g a m e n u t u p i m u a t a n p o s i t i f n y a d a n m e n y e b a b k a n p e n u r u n a n p H o d a n m e n i n g k a t k a n m u a t a n n e g a t i f n y a ( V a n R a n s t , 1 9 9 5 ) . B o n i a o ( 2 0 0 0 ) m e m b e r i k a n 1 0 % b a h a n o r g a n i k b e r u p a g a m b u t p a d a t a n a h g u n u n g a p i d a r i F i l i p i n a d a n m e n d a p a t k a n p e n u r u n a n p H o s e b e s a r 0 . 5 - 1.1 u n i t s e t e l a h d i i n k u b a s i k a n s e l a m a 9 b u l a n . B o k a s h i a d a l a h b a h a n o r g a n i k y a n g d i f e r m e n t a s i k a n d e n g a n m i k r o o r g a n i s m e p e n d e k o m p o s i s i d a n s e t a r a d e n g a n k o m p o s p a d a p e r t a n i a n o r g a n i k t r a d i s i o n a l ( S a n g a k k a r a , 2 0 0 4 ) . B a h a n o r g a n i k y a n g d a p a t d i j a d i k a n b o k a s h i a n t a r a l a i n s e k a m p a d i , j e r a m i , l i m b a h p a b r i k m i n y a k g o r e n g , l i m b a h p a b r i k k e r t a s , s e r b u k g e r g a j i , k u l i t b u a h - b u a h a n d a r i i n d u s t r i b u a h d a n m a k a n a n ,
t a n d a n k o s o n g k e l a p a s a w i t , d l l ( M u n e n e , 2 0 0 4 ) . B o k a s h i m e r u p a k a n s o l u s i p e m a n f a a t a n l i m b a h m e n j a d i b a h a n y a n g b e r m a n f a a t d a n b e m i l a i e k o n o m i ( P a r e n g k u a n , 2 0 0 4 ) . S e k a m p a d i d a p a t d i j a d i k a n b o k a s h i d a n b i s a d i p e r o l e h d e n g a n m u d a h d i I n d o n e s i a . B o k a s h i s e k a m p a d i m e m p u n y a i k a n d u n g a n h a r a y a n g c u k u p t i n g g i s e p e r t i N -
NH4
d a nN
-NO3
m a s i n g - m a s i n g 1 0 0 7 d a n 8 5 p p m s e r t a k a n d u n g a n P t e r s e d i a m e n c a p a i 1 5 4 9 - 9 9 3 4 p p m y a n g m e m p e r l i h a t k a n b a h w a b o k a s h i s e k a m p a d i m e r u p a k a n s u m b e r h a r a y a n g b a i k ( Y a m a d a et al, 1 9 9 7 ) . S e l a i n i t u , s e k a m p a d i m e n g a n d u n g s e j u m l a h s e n y a w a s i l i k a t d a l a m i k a t a n k i m i a n y a s e p e r t i t a n a m a n g r a m i n e a e l a i n n y a ( R u b i U a , 2 0 0 4 ) . P e n g g u n a a n b o k a s h i s e k a m p a d i s e b a g a i a m e l i o r a n t a n a h a b u g u n u n g a p i b e l u m b a n y a k d i l a p o r k a n w a l a u p u n s e b a g a i a m e l i o r a n b o k a s h i s e k a m p a d i d a p a t b e r f u n g s i g a n d a d a l a m m e n u r u n k a n p H o y a i t u s e b a g a i b a h a n o r g a n i k i t u s e n d i r i y a n g m e m p u n y a i p H o r e n d a h s e r t a s e b a g a i i o n s i l i k a t y a n g m e r u p a k a n a n i o n b e r v a l e n s i t i n g g i y a n g j u g a d a p a t m e n u r u n k a n p H o . 2.3 Hipotesis D a r i k e r a n g k a p e m i k i r a n d i a t a s m a k a d i a j u k a n h i p o t e s i s s e b a g a i b e r i k u t : 1 . A m e l i o r a n t e r a k b a j a , b a t u a n f o s f a t d a n b o k a s h i s e k a m p a d i d a p a t m e n u r u n k a n p H o . 2 . A m e l i o r a n t e r a k b a j a , b a t u a n f o s f a t d a n b o k a s h i s e k a m p a d i d a p a t m e n u r u n k a n r e t e n s i P 3 . A m e l i o r a n t e r a k b a j a , b a t u a n f o s f a t d a n b o k a s h i s e k a m p a d i d a p a t m e n i n g k a t k a n K T K .3.1 Waktu danTempat Penelitian P e n e l i t i a n i n i d i l a k u k a n p a d a b u l a n A g u s t u s 2 0 0 8 h i n g g a J u l i 2 0 0 9 , d a n d i l a k u k a n p a d a b e b e r a p a t e m p a t y a i t u d i l a p a n g a n , d i l a b o r a t o r i u m d a n d i r u m a h k a c a . P e n e l i t i a n l a p a n g a n d i l a k u k a n p a d a t i g a l o k a s i A n d i s o l d i J a w a B a r a t p a d a w i l a y a h y a n g b e r k e m b a n g d a i i a b u g u n u n g a p i y a i t u : D e s a C i k o l e , K e c a m a t a n L e m b a n g , K a b u p a t e n B a n d u n g ; D e s a P a t e n g a n , K e c a m a t a n R a n c a b a l i , K a b u p a t e n B a n d u n g ; d a n D e s a P u l o s a r i , K e c a m a t a n P a n g a l e n g a n , K a b u p a t e n B a n d u n g u n t u k m e n g a m b i l s a m p e l t a n a h p e n e l i t i a n . I n k u b a s i t a n a h d e n g a n a m e l i o r a n d i l a k u k a n d i l a b o r a t o r i u m . A n a l i s i s l a b o r a t o r i u m d i l a k u k a n u n t u k b e r b a g a i a n a l i s i s t a n a h m e n g e t a h u i p e r u b a h a n n i l a i p H o r e t e n s i P d a n K T K .
3.2 Bahan dan Alat
B a h a n d a n a l a t y a n g d i g u n a k a n d a l a m p e n e l i t i a n i n i a d a l a h : 1 . T a n a h A n d i s o l h a s i l e r u p s i G . T a n g k u b a n P a r a h u , G . P a t u h a d a n G . T i l u 2 . B e r b a g a i b a h a n k i m i a u n t u k a n a l i s i s t a n a h d a n t a n a m a n 3 . P e t a g e o l o g i y a n g m e l i p u t i : a. P e t a g e o l o g i l e m b a r B a n d u n g s k a l a 1 : 1 0 0 . 0 0 0 ( S i l i t o n g a , 2 0 0 3 ) b . P e t a g e o l o g i l e m b a r S i n d a n g b a r a n g d a n B a n d a r w a r u s k a l a 1 : 1 0 0 . 0 0 0 ( K o e s m o n o d k k . , 1 9 9 6 ) . c. P e t a g e o l o g i l e m b a r G a r u t d a n P a m e u n g p e u k s k a l a 1 : 1 0 0 . 0 0 0 ( A l z w a r d k k . , 1 9 9 2 ) . 1 1
4 . P e t a p e n g g u n a a n l a h a n K a b u p a t e n B a n d u n g s k a l a 1 : 1 2 5 . 0 0 0 ( B a d a n
P e r e n c a n a a n D a e r a h , 2 0 0 8 ) .
5 . P e t a j e n i s t a n a h K a b u p a t e n B a n d u n g s k a l a 1 : 1 2 5 . 0 0 0 ( B a d a n P e r e n c a n a a n
D a e r a h , 2 0 0 8 ) .
6. D a t a i k l i m d a e r a h L e m b a n g , C i w i d e y , P a n g a l e n g a n 10 t a h u n t e r a k h i r
7 . P e r a l a t a n l a p a n g a n a n t a r a l a i n : k e r t a s d e s k r i p s i , abmy hand level, k a n t o n g p l a s t i k , p i s a u , b o r t a n a h ( b o r B e i g i a ) , m e t e r a n , l a b e l , k a m e r a f o t o , Miinsell Soil Color Chart
d a n GPS {Global Position System).
8. P e r a l a t a n S t u d i o : S o f t w a r e M a p l n f o P r o f e s s i o n a l 7.5 d a n A r c v i e w G I S 9 . A m e l i o r a n t e r a k b a j a , b a t u a n f o s f a t d a n b o k a s h i s e k a m p a d i 3.3 Metode Penelitian P e n e l i t i a n i n i m e n g g u n a k a n b e b e r a p a m e t o d e y a n g s e s u a i d e n g a n t a h a p a n p e n e l i t i a n : 1 ) P e n e l i t i a n l a p a n g a n u n t u k m e m a s t i k a n l o k a s i p e n g a m b i l a n s a m p e l a d a l a h A n d i s o l y a n g b e r a s a l d a r i h a s i l e r u p s i g u n u n g a p i b e r p e d o m a n p a d a p e t a t a n a h d a n p e t a g e o l o g i , s e r t a u n t u k m e n g a m b i l s a m p e l t a n a h 2 ) P e n e l i t i a n p e n g a r u h a m e l i o r a s i t e r h a d a p r e t e n s i P A n d i s o l m e n g g u n a k a n R a n c a n g a n A c a k L e n g k a p p o l a f a k t o r i a l d e n g a n d u a f a k t o r . F a k t o r p e r t a m a a d a l a h A n d i s o l d a r i 3 l o k a s i . F a k t o r k e d u a a d a l a h j e n i s a m e l i o r a n . A m e l i o r a n d i i n k u b a s i k a n k e d a l a m t a n a h s e l a m a e m p a t b u l a n k e m u d i a n d i a n a l i s i s p e n g a r u h a m e l i o r a n t e r h a d a p r e t e n s i P d a n K T K p a d a b u l a n k e 2 , 3 d a n 4 .
3.3.1 Penelitian L a p a n g ? n K e g i a t a n t a h a p i n i a d a l a h i n v e n t a r i s a s i p e t a d a n d a t a s e p e r t i p e t a g e o l o g i , t o p o g r a f i , t a n a h , p e n g g u n a a n l a h a n , d a n d a t a i k l i m . H a l i n i d i l a k u k a n u n t u k m e m u d a h k a n p e n e n t u a n l o k a s i p e n g a m a t a n d a n p e n g a m b i l a n s a m p e l t a n a h . P e n e n t u a n l e t a k l o k a s i p e n g a m a t a n d i l a k u k a n m e l a l u i overlay p e t a - p e t a y a n g a d a s e h i n g g a m e n g h a s i l k a n p e t a k o m b i n a s i p e n y e b a r a n b a h a n i n d u k d a n j e n i s t a n a h d a n v e g e t a s i a l a m i y a n g s a m a s e h i n g g a d i p e r o l e h l o k a s i p e n g a m a t a n y a n g s e s u a i . P e n g a m b i l a n c o n t o h t a n a h d i l a k u k a n p a d a l o k a s i y a n g t e r m a s u k d a l a m Landform Fo/ca« ( V ) p a d a a r e a l h u t a n a l a m i ( G a m b a r 1 ) . G a m b a r 1 . V e g e t a s i d a n P e n g g u n a a n L a h a n D a e r a h P e n e l i t i a n ( a ) A n d i s o l h a s i l e r u p s i G . T a n g k u b a n P a r a h u ( T P R ) ( b ) A n d i s o l h a s i l e r u p s i G . P a t u h a ( P T H ) , ( c ) A n d i s o l h a s i l e r u p s i G . T i l u ( T L U )
P e r c o b a a n i n k u b a s i d a n r u m a h k a c a m e m e r l u k a n t a n a h y a n g d i a m b i l d a r i l a p i s a n t e r a t a s ( 0 - 2 0 c m ) . C o n t o h t a n a h i n i d i a m b i l s e c a r a k o m p o s i t d a r i s e t i a p t i t i k p e n g a m a t a n k e m u d i a n d i c a m p u r m e r a t a b e r d a s a r k a n l o k a s i n y a , s e h i n g g a d i p e r o l e h t i g a c o n t o h t a n a h d a r i t i g a l o k a s i m a s i n g - m a s i n g s e k i t a r 2 0 0 k g . 3.3.2 Analisis Laboratorium A n a l i s i s l a b o r a t o r i u m d i g u n a k a n u n t u k m e n g u j i h i p o t e s i s 1 d a n 2 , y a i t u u n t u k m e n g e t a h u i p e r u b a h a n n i l a i p H o , r e t e n s i P d a n K T K . p H o T a n a h d i j e n u h k a n d e n g a n C a u n t u k m e n g h a s i l k a n k e s e t i m b a n g a n d e n g a n C a C l 2 0 . 0 0 2 M . N i l a i p H d i a t u r p a d a b e b e r a p a n i l a i a n t a r a p H 4 s a m p a i 7 d e n g a n p e n a m b a h a n K O H a t a u H C l e n c e r . K e t i k a k e s t a b i l a n t e r c a p a i , p H d i u k u r d a n d i t e t a p k a n s e b a g a i p H o . o o i - T a n a h y a n g s a m a k e m u d i a n d i s e t i m b a n g k a n d e n g a n l a r u t a n C a C l i 2 M d a n n i l a i p H d i u k u r k e m b a l i d a n d i c a t a t s e b a g a i p H o . o s - S e l i s i h a n t a r a p H o . o s d e n g a n p H o. 0 0 2 d i n a m a k a n d e l t a p H ( A p H ) . D e l t a p H k e m u d i a n d i p l o t k a n t e r h a d a p p H o. o o 2 - T i t i k s a a t A p H s a m a d e n g a n n o l d i s e b u t d e n g a n p H o .
Retensi P (Blakemore et ai, 1987)
T a n a h k e r i n g u d a r a 5 g d i k o c o k d e n g a n 2 5 m L l a r u t a n r e t e n s i P s e l a m a 1 6
j a m . R e t e n s i P d i t e n t u k a n d e n g a n spectrophotometer d a n cuvette b e r u k u r a n 1 c m .
Kapasitas T u k a r Kation dan Kation Dapat Ditukar
K T K d i t e n t u k a n d e n g a n m e n c u c i 5 g t a n a h y a n g t i d a k d i k e r i n g u d a r a k a n
N H 4 O A C d i h i l a n g k a n d e n g a n e t a n o l 9 5 %. J u m l a h i o n N H 4 * y a n g d i t a h a n p a d a
t a n a h s e t a r a d e n g a n K T K . K a t i o n C a * ^ M g ^ ^ N a ^ , K ^ d i t e n t u k a n d e n g a n A A S
( V a n R e u w i j k , 1 9 9 2 ) .
3.3.3 Percobaan Inkubasi di Laboratorium
K e g i a t a n i n i d i l a k s a n a k a n u n t u k m e n g u j i h i p o t e s i s . P e n g u j i a n i n i b e r t u j u a n u n t u k m e l i h a t k e m a m p u a n a m e l i o r a n t e r a k b a j a , b a t u a n f o s f a t d a n b o k a s h i s e k a m p a d i d e n g a n b e r b a g a i t a k a r a n d a l a m m e n u r u n k a n p H o , r e t e n s i f o s f a t s e i t a m e n i n g k a t k a n K T K p a d a A n d i s o l d i J a w a B a r a t . P e n i l a i a n d i l a k u k a n b e r d a s a r k a n p e r u b a h a n k a r a k t e r i s t i k t a n a h t e r b a i k y a n g d i p e r o l e h s e t e l a h i n k u b a s i . 3.3.3.1 Metode Percobaan Rancangan Perlakuan P e r c o b a a n i n k u b a s i a m e l i o r a n d i l a b o r a t o r i u m m e n g g u n a k a n R a n c a n g a n A c a k L e n g k a p ( R A L ) y a n g d i s u s u n s e c a r a f a k t o r i a l y a n g t e r d i r i d a r i d u a f a k t o r . F a k t o r p e r t a m a a d a l a h t a n a h A n d i s o l y a n g t e r d i r i d a r i t i g a t a r a f y a i t u A n d i s o l y a n g b e r a s a l d a r i t i g a l o k a s i h a s i l e r u p s i t i g a g u n u n g a p i . F a k t o r k e d u a a d a l a h a m e l i o r a n y a n g t e r d i r i d a r i 4 t a r a f : k o n t r o l ( t a n p a a m e l i o r a n ) , t e r a k b a j a , b a t u a n f o s f a t d a n b o k a s h i s e k a m p a d i . S e t i a p p e r l a k u a n d i u l a n g d u a k a l i , s e h i n g g a t e r d a p a t 3 x 4 x 2 = 2 4 u n i t p e r c o b a a n . K e d u a f a k t o r y a n g d i m a k s u d a d a l a h : ( 1 ) F a k t o r I : T a n a h A n d i s o l ( T ) : ti = A n d i s o l h a s i l e r u p s i G . T a n g k u b a n P a r a h u t2 = A n d i s o l h a s i l e r u p s i G . P a t u h a t3 = A n d i s o l h a s i l e r u p s i G . T i l u
( 2 ) F a k t o r I I : A m e l i o r a n ( A ) b e r u p a t e r a k b a j a , b a t u a n f o s f a t d a n b o k a s h i s e k a m p a d i y a n g d i b e r i k a n b e r d a s a r k a n b e r a t t a n a h ( % b e r a t ) . T a n a h y a n g d i g u n a k a n a d a l a h t a n a h 3 k g ( s e t a r a k e r i n g u d a r a ) , s e h i n g g a p e m b e r i a n a m e l i o r a n a d a l a h s e b a g a i b e r i k u t : ao = k o n t r o l ( t a n p a a m e l i o r a n ) a i = t e r a k b a j a 7 . 5 % ( 2 2 5 g t e r a k b a j a p o l i b e g " ' ) a 2 = b a t u a n f o s f a t 7 . 5 % ( 2 2 5 g b a t u a n f o s f a t p o l i b e g " ' ) a3 = b o k a s h i s e k a m p a d i 7 . 5 % ( 2 2 5 g b o k a s h i s e k a m p a d i p o l i b e g " ' ) K o m b i n a s i p e r l a k u a n d a p a t d i l i h a t p a d a T a b e l 1 b e r i k u t . T a b e l 1 . K o m b i n a s i P e r l a k u a n T a n a h d a n A m e l i o r a n Tanah (T) Amelioran (A) ti t2
ao aoti aot2 aot3
ai aiti a i 2 aits
a2t2 a2t3
as asti a3t2 a3t3
Rancangan Respons
V a r i a b e l r e s p o n s y a n g d i a m a t i p a d a b u l a n k e 2 , 3 d a n 4 i n k u b a s i a d a l a h :
- p H o
- r e t e n s i P ( B l a k e m o r e et al., 1 9 8 7 ) - K T K ( A m o n i u m A s e t a t )
Rancangan Analisis D a t a h a s i l p e n g a m a t a n d i a n a l i s i s d e n g a n analysis of variance ( a n o v a ) p a d a t a r a f a o.os u n t u k m e n g e t a h u i a p a k a h p e r l a k u a n m e m b e r i k a n e f e k b e r m a k n a t e r h a d a p s e t i a p v a r i a b l e r e s p o n s y a n g d i a m a t i . E f e k p e r l a k u a n y a n g b e r m a k n a d i u j i l a n j u t d e n g a n u j i D u n c a n ( S t e e l d a n T o r r i e , 1 9 8 0 , A g r e s t i , 1 9 9 6 ) . P e n g u k u r a n p a r a m e t e r y a n g b e r u l a n g ( b u l a n k e 2 , 3 d a n 4 ) p a d a p e r c o b a a n i n k u b a s i , d i l a k u k a n d e n g a n m e n a m b a h k a n w a k t u p e n g a m a t a n s e b a g a i s a t u f a k t o r t a m b a h a n d a l a m p e r c o b a a n d a n m e m p e r l a k u k a n n y a s e b a g a i a n a k p e t a k a t a u s a t u a n p e r c o b a a n t e r k e c i l ( G o m e z d a n G o m e z , 1 9 8 4 ) . A n a l i s i s s i d i k r a g a m u n t u k p e r c o b a a n i n k u b a s i d e n g a n a m e l i o r a n d i t a m p i l k a n p a d a T a b e l 2 . T a b e l 2 . A n a l i s i s s i d i k r a g a m p e r c o b a a n i n k u b a s i d e n g a n a m e l i o r a n Sumber K e r a g a m a n ^u'^^^^^ J K K T F m , F , P e r l a k u a n T a n a h ( T ) ( t - 1 ) J K ( T ) K T ( T ) K T ( T ) / K T G a A m e l i o r a n ( A ) ( a - 1 ) J K ( A ) K T ( A ) K T ( A ) / K T G a T a n a h x A m e l i o r a n ( T A ) ( t - l ) ( a - l ) J K ( T A ) K T ( T A ) K T ( T A ) / K T G a G a l a t p e t a k u t a m a ( a ) a t ( r - l ) J K G a K T G a W a k t u ( W ) ( w - 1 ) J K ( W ) K T ( W ) K T ( W ) / K T G b T a n a h x W a k t u ( T W ) ( t - l ) ( w - l ) J K ( T W ) K T ( T W ) K T ( T W ) / K T G b A m e l i o r a n x W a k t u ( A W ) ( a - l ) ( w - l ) J K ( A W ) K T ( A W ) K T ( A W ) / K T G b T a n a h x A m e l i o r a n x W a k t u ( t - l ) ( a - l ) ( v v - J K ( T A W K T ( T A K T ( T A W ) / K T G ( T A W ) 1 ) ) W ) b G a l a t a n a k p e t a k ( b ) a t ( r - l ) ( w - l ) J K G b K T G b T o t a l r t a w - 1 U n t u k m e l i h a t p o l a r e s p o n s p a r a m e t e r t e r h a d a p w a k t u , d i g u n a k a n b e n t u k p e r s a m a a n r e g r e s i Y = P o + P i x + p 2 x ^ . N a m u n j i k a a d a s e b a r a n d a t a y a n g s e b a r a n n y a t i d a k k u a d r a t i k , d i g u n a k a n b e n t u k p e r s a m a a n r e g r e s i y a n g t e r g a n t u n g p a d a s e b a r a n d a t a t e r s e b u t .
3.3.3.2 Pelaksanaan Percobaan Inkubasi di Laboratorium L a p i s a n a t a s t a n a l i u n t u k i n k u b a s i i n i d i a m b i l s e c a r a k o m p o s i t d a r i k e d a l a m a n 0 - 2 0 c m p a d a k e t i g a l o k a s i p e n e l i t i a n . S e b a n y a k 3 k g t a n a h ( s e t a r a k e r i n g u d a r a ) u n t u k s e t i a p p e r l a k u a n d i m a s u k k a n k e d a l a m p o l i b e g d a n d i i n k u b a s i d e n g a n t e r a k b a j a , b a t u a n f o s f a t d a n b o k a s h i s e k a m p a d i s e s u a i p e r l a k u a n s e l a m a 4 b u l a n . J a n g k a w a k t u i n k u b a s i 4 b u l a n b e r p e d o m a n p a d a F i a n t i s ( 2 0 0 0 ) y a n g m e l a k u k a n i n k u b a s i s e l a m a 6 b u l a n d e n g a n a m e l i o r a n b e r u p a k a l s i u m s i l i k a t d a n s u p e r f o s f a t , n a m u n p a d a w a k t u i n k u b a s i 4 b u l a n t e l a h m e n d a p a t k a n p e r u b a h a n k a r a k t e r i s t i k t a n a h . T a n a h d a n a m e l i o r a n d i a d u k s e c a r a m e r a t a , d i m a s u k k a n k e d a l a m p o l i b e g d a n d i t a m b a h k a n a i r h i n g g a m e n c a p a i k a p a s i t a s l a p a n g . P o l i b e g k e m u d i a n d i t u t u p u n t u k m e n c e g a h k e k e r i n g a n . T e r a k b a j a d i p e r o l e h d a r i P T K r a k a t a u S t e e l I n d o n e s i a d a n d i h a l u s k a n h i n g g a l o l o s s a r i n g a n 8 0 m e s h d i L a b o r a t o r i u m T e k n i k M e t a l u r g i U n i v e r i ^ i t a s J e n d r a l A h m a d Y a n i . A n a l i s i s u n s u r t e r a k b a j a d i t a m p i l k a n p a d a L a m p i r a n 1 . B a t u a n f o s f a t d i p e r o l e h d a r i P T . T a n i S u g i h d e n g a n k e h a l u s a n l o l o s s a r i n g a n 8 0 m e s h . K a r a k t e r i s t i k b a t u a n f o s f a t d i t a m p i l k a n p a d a L a m p i r a n 2 . B o k a s h i s e k a m p a d i d i b u a t d e n g a n m e n c a m p u r s e k a m p a d i d e n g a n E M 4 {Effective Microorganism 4). P r o s e d u r p e m b u a t a n b o k a s h i d i t a m p i l k a n p a d a L a m p i r a n 3 . K a n d u n g a n S i p a d a b o k a s h i d i a n a l i s i s d i L a b o r a t o r i u m B a l a i B e s a r K e r a m i k . H a s i l a n a l i s i s k i m i a b o k a s h i d i t a m p i l k a n p a d a L a m p i r a n 4 . S e l a m a m a s a i n k u b a s i , p a d a b u l a n k e 2 , 3 d a n 4 b u l a n , t a n a h d a l a m s e t i a p p o l i b e g d i a m b i l u n t u k a n a l i s i s p H o , r e t e n s i P , d a n K T K .
4.1 Deskripsi Umum Daerah Penelitian 4.1.1 L o k a s i Daerah Penelitian L o k a s i p e n e l i t i a n a d a l a h a r e a l A n d i s o l y a n g b e r k e m b a n g d a r i b e b e r a p a e r u p s i g u n u n g a p i d e n g a n s i f a t d a n u m u r g e o l o g i b a h a n i n d u k y a n g b e r b e d a . S i f a t b a h a n i n d u k y a n g m e n j a d i f o k u s a d a l a h a n d e s i t , a n d e s i t b a s a l a n d a n b a s a l , s e m e n t a r a u m u r g e o l o g i b a h a n i n d u k a d a l a h H o l o s e n d a n P l e i s t o s e n . I n f o r m a s i m e n g e n a i h a l t e r s e b u t d i p e r o l e h m e l a l u i p e t a t a n a h d a n p e t a g e o l o g i . L o k a s i p e n e l i t i a n d i t a m p i l k a n p a d a T a b e l 3 d e n g a n r i n c i a n : 1 ) T P R : D e s a C i k o l e , K e c a m a t a n L e m b a n g , h a s i l e r u p s i G . T a n g k u b a n P a r a h u , b e r b a h a n i n d u k a n d e s i t d e n g a n u m u r g e o l o g i H o l o s e n 2 ) P T H : D e s a P a t e n g a n , K e c a m a t a n R a n c a b a l i , h a s i l e r u p s i G . P a t u h a , b e r b a h a n i n d u k a n d e s i t b a s a l a n d e n g a n u m u r g e o l o g i H o l o s e n 3 ) T L U : D e s a P u l o s a r i , K e c a m a t a n P a n g a l e n g a n , h a s i l e r u p s i G . T i l u , b e r b a h a n i n d u k b a s a l d e n g a n u m u r g e o l o g i P l e i s t o s e n T a b e l 3 . L o k a s i , s u m b e r e r u p s i , s i f a t b a h a n i n d u k d a n u m u r g e o l o g i b a h a n i n d u k A n d i s o l d a e r a h p e n e l i t i a n
Lokasi Sumber erupsi Sifat bahan induk Umur geologi
T P R , D e s a C i k o l e G . T a n g k u b a n P a r a h u P T H , D e s a P a t e n g a n G . P a t u h a T L U , D e s a P u l o s a r i G . T i l u o 1 . I ) Q^]u^^^^ n r \ n i A n d e s i t ' ^ A n d e s i t b a s a l a n ^ * B a s a P ' H o l o s e n H o l o s e n ' ^ P l e i s t o s e n ' ^ ' S u m b e r : S i l i t o n g a , 2 0 0 3 K o e s m o n o d a n , 1 9 7 6 A l z w a r , d k k . , 1 9 7 6 1 9
4.1.2 Topografi Daerah Penelitian L o l c a s i p e n e l i t i a n m e r u p a k a n d a e r a h d e n g a n r e l i e f d a t a r d a n b e r g e l o m b a n g t e r d i r i d a r i l e r e n g a t a s , t e n g a h d a n b a w a h . L e r e n g a t a s m e r u p a k a n d a e r a h y a n g b e r g e l o m b a n g d e n g a n k e m i r i n g a n l e r e n g 8 - 1 5 %, s e d a n g k a n l e r e n g t e n g a h d a n b a w a h m e r u p a k a n d a e r a h y a n g r e l a t i f d a t a r d e n g a n k e m i r i n g a n l e r e n g b e r k i s a r a n t a r a 3 - 8 %. P e m b u a t a n p r o f i l t a n a h d i l a k u k a n p a d a d a e r a h d e n g a n t o p o g r a f i y a n g s a m a ( 8 - 1 5 % ) d i s e k i t a r l e r e n g a t a s . P r o f i l T P R b e r a d a p a d a l e r e n g s e k i t a r 1 2 %, p r o f i l P T H b e r a d a p a d a l e r e n g s e k i t a r 8 % d a n p r o f i l T L U b e r a d a p a d a l e r e n g s e k i t a r 1 0 % .
4.1.3 Geologi Daerah Penelitian
1 ) P r o f i l T P R t e r l e t a k p a d a l e r e n g s e l a t a n G . T a n g k u b a n P a r a h u , b e r a s a l d a r i z a m a n H o l o s e n ( 1 0 . 0 0 0 y a n g l a l u s a m p a i s e k a r a n g ) , b e r u p a t u f p a s i r k r i s t a l h o r n b l e n d e , l a h a r l a p u k k e m e r a h a n , l a p i s a n l a p i l i d a n b r e k s i d a r i G . D a n o d a n G . T a n g k u b a n P a r a h u y a n g d i s i m b j l k a n d e n g a n Q y d ( S i l i t o n g a , 2 0 0 3 ) 2 ) P r o f i l P T H t e r l e t a k p a d a l e r e n g u t a r a G . P a t u h a , b e r a s a l d a r i z a m a n k u a r t e r H o l o s e n b e r u p a l a h a r G . P a t u h a , m e n g a n d u n g t u f p a s i r a n a b u - a b u d a n p l a g i o k l a s y a n g d i s i m b o l k a n d e n g a n Q v ( p , l ) ( K o e s m o n o d k k , 1 9 9 6 ) . 3 ) P r o f i l T L U t e r l e t a k p a d a l e r e n g s e l a t a n G . T i l u , b e r a s a l d a r i b a t u a n i n d u k b e r u m u r P l e i s t o s e n ( 1 . 6 j u t a - 1 0 . 0 0 0 t a h u n y a n g l a l u ) b e r u p a b a t u a n g u n u n g a p i t u a T i l u y a n g m e n g a n d u n g t u f , b r e k s i l a h a r d e n g a n m e n g a n d u n g s e d i k i t b a t u a p u n g d a n l a v a y a n g d i s i m b o l k a n d e n g a n Q t l ( A l z w a r d k k , 1 9 9 2 ) .
4.1.4 Penggunaan L a h a n dan Vegetasi
P e n g g u n a a n l a h a n b e r u p a h u t a n p r o d u k s i d a n h u t a n k o n s e r v a s i :
1 ) L o k a s i T P R a d a l a h h u t a n k o n s e r v a s i p i n u s (Pinus mercusii). T e r d a p a t j u g a v e g e t a s i r u m p u t g a j a h (Pueraria phaseoloides) d a n r a s a m a l a {Altingia exelsd). S e b a g i a n a r e a l h u t a n d i g u n a k a n o l e h D i n a s K e h u t a n a n s e t e m p a t s e b a g a i a r e a l
w i s a t a outbound d a n p e r k e m a h a n , n a m u n b a g i a n t e r b e s a m y a a d a l a h b e r u p a h u t a n p i n u s
2 ) L o k a s i G . P a t u h a ( P T H ) a d a l a h h u t a n k o n s e r v a s i k a y u p u t i h {Melaleuca leucadendron), r a s a m a l a {Altingia exelsa), h u m k o n e n g {Litsea angulata) d a n p i n u s {Pinus mercusii). D a e r a h i n i d i k e l o l a o l e h P e r u m P e r h u t a n i d a n s e b a g i a n l o k a s i n y a d i m a n f a a t k a n s e b a g a i P e m a n d i a n A i r P a n a s C i m a n g g u .
3 ) L o k a s i G . T i l u ( T L U ) a d a l a h h u t a n k o n s e r v a s i d a n p r o d u k s i p i n u s {Pinus mercusii), k u r a y {Trema ampinensi), r u m p u t g a j a h {Pueraria phaseoloides) d a n r a s a m a l a {Altingia exelsa). H u t a n p i n u s s e l a i n b e r f u n g s i s e b a g a i h u t a n k o n s e r v a s i , j u g a m e r u p a k a n h u t a n p r o d u k s i k a r e n a g e t a h p i n u s d i s a d a p u n t u k d i j a d i k a n b a h a n k a r b o l ( b a h a n d a s a r p e m b e r s i h d a n p e w a n g i ) . 4.1.5 Iklim L o k a s i p e n e l i t i a n i n i m e m i l i k i r e j i m k e l e m b a b a n u d i k y a i t u t a n a h t i d a k p e r n a h k e r i n g 9 0 h a r i ( k u m u l a t i f ) s e t i a p t a h u n . T a b e l m e m p e r l i h a t k a n p r o f i l T P R d a n T L U m e m i l i k i r e j i m t e m p e r a t u r i s o h i p e r t h e r m i k ( s u h u t a h u n a n r a t a - r a t a l e b i h d a r i 22*^ C , d a n s e l i s i h s u h u r a t a - r a t a m u s i m p a n a s d a n m u s i m d i n g i n k u r a n g d a r i 6° C ) , s e m e n t a r a p r o f i l P T H m e m i l i k i r e j i m t e m p e r a t u r i s o t e r m i k ( s u h u
t a h u n a n r a t a - r a t a 1 5 - 2 2 C , d a n s e U s i h s u h u r a t a - r a t a m u s i m p a n a s d a n m u s i m d i n g i n k u r a n g d a r i 6^^ C ) . B e r d a s a r k a n d a t a c u r a h h u j a n p a d a p e r i o d e s e p u l u h t a h u n t e r a k h i r d a r i P T P N V I I I d a n b e r p e d o m a n p a d a p e r h i t u n g a n S c h m i d t - F e r g u s s o n ( 1 9 5 1 ) , d a e r a h L e m b a n g d a n C i w i d e y ( T P R d a n P T H ) a d a l a h d a e r a h d e n g a n i k l i m t i p e B d a n d a e r a h P a n g a l e n g a n ( T L U ) a d a l a h d a e r a h d e n g a n i k l i m t i p e C . B e r d a s a r k a n d a t a c u r a h h u j a n s e t i a p l o k a s i p e n e l i t i a n s e l a m a s e p u l u h t a h u n t e r a k h i r ( 1 9 9 8 - 2 0 0 8 ) t e r s e b u t , d i p e r o l e h d a t a s e b a g a i s e b a g a i b e r i k u t : 1 ) L o k a s i T P R : c u r a h h u j a n 2 6 3 7 5 3 6 9 m m / t a h u n . R a t a r a t a b u l a n k e r i n g 1 -2 b u l a n / ' t a h u n d a n r a t a - r a t a b u l a n b a s a h 8 b u l a n / t a h u n . 2 ) L o k a s i P T H : 2 4 2 0 - 4 1 3 1 m m / t a h u n . R a t a - r a t a b u l a n k e r i n g 1 - 2 b u l a n / t a h u n d a n r a t a - r a t a b u l a n b a s a h 7 - 8 b u l a n / t a h u n . 3 ) L o k a s i T L U : 1 9 3 8 - 3 4 7 1 m m / t a h u n . R a t a - r a t a b u l a n k e r i n g 1 - 2 b u l a n / t a h u n d a n r a t a - r a t a b u l a n b a s a h 6 - 7 b u l a n / t a h u n . T a b e l 4 . D a t a h a r i h u j a n , c u r a h h u j a n , s u h u u d a r a d a n s u h u t a n a h p a d a l o k a s i p e n e l i t i a n T a n g k u b a n P a r a h u P a t u h a T i l u ( 1 3 6 5 m i d p l ) ( 1 7 9 8 m d p i ) ( 1 4 8 6 m d p i ) B u l a n H H C H S U S T H H C H S U S T H H C H S U S T ( m m ) (°C) CC) ( m m ) ec) ( " C ) ( m m ) ( " C ) CC) J a n u a r i 15 3 8 2 2 0 . 6 2 3 . 1 2 1 3 0 3 1 5 . 9 1 8 . 4 15 3 2 1 2 0 . 9 2 3 . 4 F e b r u a r i 1 5 7 6 2 2 0 . 7 2 3 . 2 2 4 3 1 8 1 5 . 9 1 8 . 4 16 3 8 9 2 0 . 4 2 2 . 9 M a r e t 13 5 8 0 2 0 . 9 2 3 . 4 2 6 4 0 5 16.1 1 8 . 6 15 4 2 7 2 0 . 6 2 3 . 1 A p r i l 1 6 6 9 2 2 1 . 5 2 4 . 4 1 1 1 4 6 16.1 1 8 . 6 1 0 2 1 0 2 0 . 8 2 3 . 3 M e i 1 4 4 8 4 2 1 . 3 2 3 . 8 1 1 1 4 6 1 6 . 2 1 8 . 7 7 7 1 2 0 . 8 2 3 . 3 J u n i 7 1 1 7 2 1 . 8 2 4 . 3 4 5 6 1 6 . 2 1 8 . 7 15 1 3 3 2 1 . 2 2 3 . 7 J u l i 8 1 2 5 2 3 . 1 2 5 . 6 6 6 4 1 6 . 4 1 8 . 9 6 7 1 2 1 . 5 2 4 . 0 A g u s t u s 0 0 2 3 . 8 2 6 . 3 1 5 1 6 . 4 1 8 . 9 3 2 6 2 1 . 5 2 4 . 0 S e p t e m b e r 1 0 2 0 1 2 2 . 9 2 5 . 4 5 7 6 1 6 . 3 1 8 . 8 6 9 0 2 2 . 1 2 4 . 6 O k t o b e r 8 1 4 8 2 2 . 8 2 5 . 3 3 2 8 16.1 1 8 . 6 6 9 3 2 2 . 5 2 5 . 0 N o v e m b e r 1 9 3 9 5 2 1 . 9 2 4 . 4 17 4 6 4 16.1 1 8 . 6 9 1 3 6 2 2 . 1 2 4 . 6 D e s e m b e r 1 9 6 1 0 2 1 . 6 2 4 . 1 2 1 4 7 7 16.1 1 8 . 6 2 2 3 4 6 2 1 . 1 2 3 , 6 J u m l a h 1 4 4 4 4 9 6 2 6 2 . 9 2 9 2 . 9 1 5 0 2 4 8 8 1 9 3 . 8 2 2 3 . 8 1 3 0 2 3 1 3 2 5 5 . 5 2 8 5 . 5 R a t a - r a t a 1 2 . 0 3 7 4 . 7 2 1 . 9 2 4 . 4 1 2 . 5 2 0 7 . 3 1 6 . 2 1 8 . 7 1 0 . 8 1 9 2 . 8 2 1 . 3 2 3 . 8
K e t e r a n g a n : H H = h a r i h u j a n ; C H = c u r a h h u j a n ; S U = s u h u u d a r a ; S T = s u h u t a n a h D i k u t i p d a r i h a s i l p e n g a m a t a n s e l a m a 1 0 t a h u n ( 1 9 9 8 - 2 0 0 8 ) S t a s i u n K l i m a t o l o g i L e m b a n g H a s i l p e n g a m a t a n p e n c a t a t a n s u h u u d a r a S t a s i u n K l i m a t o l o g i L e m b a n g H a s i l k o n v e r s i d a r i s u h u u d a r a ( V a n W a m b e k e , 1 9 8 5 ) D i k u t i p d a r i h a s i l p e n g a m a t a n s e l a m a 1 0 t a h u n ( 1 9 9 8 - 2 0 0 8 ) S t a s i u n K l i m a t o l o g i L e m b a n g D i k u t i p d a r i h a s i l p e n g a m a t a n s e l a m a 1 0 t a h u n ( 1 9 9 8 - 2 0 0 8 ) S t a s i u n K l i m a t o l o g i L e m b a n g
4.2 Pengaruh Amelioran Terhadap Sifat K i m i a Andisol
A n d i s o l m e r u p a k a n s a l a h s a t u t a n a h y a n g p r o d u k t i f , n a m u n m e m p u n y a i b e b e r a p a m a s a l a h s e p e r t i r e t e n s i P y a n g t i n g g i d a n m u a t a n t e r g a n t u n g p H . P e m b e r i a n a m e l i o r a n b e r t u j u a n u n t u k m e n g a t a s i m a s a l a h t e r s e b u t . A m e l i o r a n b e r u p a s i l i k a t ( t e r a k b a j a ) , f o s f a t ( b a t u a n f o s f a t ) d a n b a h a n o r g a n i k ( b o k a s h i s e k a m p a d i ) d e n g a n m u a t a n n e g a t i f y a n g t i n g g i d i h a r a p k a n m a m p u m e m b l o k m u a t a n p o s i t i f A n d i s o l , s e h i n g g a m e l e p a s k a n P y a n g t e r e t e n s i . A m e i o r a n t e r s e b u t d i h a r a p k a n j u g a m a m p u m e r u b a h k o l o i d t a n a h d e n g a n m e n u r u n k a n p H o , s e h i n g g a m u a t a n n e g a t i f t a n a h a k a n m e n i n g k a t d a n K T K b e r t a m b a h . 4.2.1 pHo T a n a h A m e l i o r a n t e r a k b a j a , b a t u a n f o s f a t d a n b o k a s h i s e k a m p a d i m e m p e r l i h a t k a n k e c e n d e r u n g a n u n t u k m e n u r u n k a n p H o t a n a h . A n a l i s i s v a r i a n s u n t u k i n t e r a k s i t a n a h , a m e l i o r a n d a n w a k t u t e r h a d a p p H o d i t a m p i l k a n p a d a L a m p i r a n 6 . G r a f i k p e r u b a h a n p H o p a d a s e t i a p l o k a s i d i t a m p i l k a n p a d a G a m b a r 2 , 3 d a n 4 . P e r l a k u a n d e n g a n t e r a k b a j a m e n u r u n k a n p H o p a d a k e t i g a l o k a s i . A n a l i s i s v a r i a n s ( L a m p i r a n 5 ) m e m p e r l i h a t k a n b a h w a t e r a k b a j a m e n u r u n k a n p H o l e b i h b a i k d i b a n d i n g k a n b a t u a n f o s f a t d a n b o k a s h i s e k a m p a d i . T e r a k b a j a m e m i l i k i
s i l i k a t y a n g t i n g g i ( L a m p i r a n 1 ) . A n i o n s i l i k a t y a n g t e r b e n t u k m e l a l u i h i d r o l i s i s s e n y a w a s i l i k a t b e r k o m p e t i s i d e n g a n m u a t a n p o s i t i f p a d a t a p a k j e r a p a n s e h i n g g a m e n g h a s i l k a n p e n u r u n a n p H o . S e l a i n i t u h i d r o l i s i s S i O m e l e p a s k a n s e j u m l a h C a , N a , M g d a n K k e d a l a m t a n a h ( M i t c h e l l , 2 0 0 4 ) , d a n m e n y e b a b k a n p e n i n g k a t a n p H ( T i s d a l e et al., 1 9 9 3 ; V a n R a n s t , 1 9 9 5 ) s e r t a j u g a d a p a t m e n u r u n k a n p H o . P e n u r u n a n p H o a k i b a t p e m b e r i a n s i l i k a t j u g a d i t e m u k a n p a d a p e n e l i t i a n B o n i a o ( 2 0 0 0 ) p a d a t a n a h a b u g u n u n g a p i d i F i l i p i n a d a n F i a n t i s ( 2 0 0 0 ) p a d a A n d i s o l d i S u m a t e r a B a r a t . K o n t r o l : p H o = 4 . 8 3 5 8 + 0 . 5 7 5 1 x - 0 . 0 7 2 7 T e r a k b a j a : p H o = 4 . 8 8 1 3 - 0 . 3 9 7 6 x + 0 . 0 5 9 1 B a t u a n f o s f a t : p H o = 4 . 8 4 7 6 + 0 . 5 0 4 2 x - 0 . 0 9 5 5 x ^ B o k a s h i s e k a m p a d ! : p H o = 4 . 8 6 2 6 + 0 . 4 7 6 7 x - 0 . 1 0 8 x ^ 6 . 6 - 0 . 5 o o 0 . 5 1.0 1.5 2 . 0 2 . 5 3 . 0 3 . 5 4 . 0 4 . 5 W a k t u i n k u b a s i ( b u l a n ) G a m b a r 2 . P e r u b a h a n p H o s e t e l a h i n k u b a s i p a d a b u l a n k e 2 , 3 d a n 4 t a n a h T P R
K o n t r o l : p H o = 4 . 7 3 4 + 1 . 4 3 6 x - 0 . 3 x ^ T e r a k b a j a : p H o = 4 . 6 8 4 + 0 . 2 1 1 x - 0 . 1 2 5 x ^ B a t u a n f o s f a t : p H o = 4 . 7 0 5 8 + 0 . 8 0 5 1 x - 0 . 2 2 2 7 B o k a s h i s e k a m p a d i : p H o = 4 . 6 8 3 5 + 1 . 0 2 6 2 x - 0 2 6 9 3 x ^ - 0 , 5 0 . 0 0 5 1.0 1,5 2 , 0 2 5 3 , 0 3 5 4 . 0 4 5 W a k t u i n k u b a s i ( b u l a n ) G a m b a r 3 . P e r u b a h a n p H o s e t e l a h i n k u b a s i p a d a b u l a n k e 2 , 3 d a n 4 t a n a h P T H R e a k s i y a n g t e r j a d i d e n g a n p e n a m b a h a n t e r a k b a j a m e r u p a k a n r e a k s i e l e k t r o s t a t i s , y a n g m e n u r u n k a n p H o m e l a l u i p e n a m b a h a n 8 1 0 4 " ^ p a d a t a p a k j e r a p a n p o s i t i f . U e h a r a d a n G i l l m a n ( 1 9 8 1 ) m e n y a t a k a n b a h w a S i 0 4 - ' ^ m e m b e n t u k l a r u t a n k e s e t i m b a n g a n p a d a t a p a k p e r t u k a r a n p o s i t i f d a n s e l a n j u t n y a m e l e p a s k a n O H " . H a l i n i m e r u p a k a n j e r a p a n s p e s i f i k d e n g a n a f i n i t a s r e n d a h s e h i n g g a s e t i a p p e n a m b a h a n S i 0 4 ' ^ m e n y e b a b k a n p H o b e r g e r a k m e n j a d i l e b i h r e n d a h d a n m u a t a n n e g a t i f b e r t a m b a h .
K o n t r o l : p H o = 4 . 2 7 2 2 1 . 0 3 1 9 x - 0 . 2 0 2 3 T e r a k b a j a : p H o = 4 . 2 6 9 5 + 0 . 4 4 8 3 x - 0 . 1 4 3 2 x ^ B a t u a n f o s f a t : p H o = 4 . 2 6 6 7 + 0 . 9 6 4 6 x - 0 . 2 3 4 1 x ^ B o k a s h i s e k a m p a d i : p H o = 4 . 2 6 3 5 + 0 . 9 7 1 2 x - 0 . 2 4 4 3 x ^ 5 . 8 5 . 6 & 4 52 5.0 4 . 8 o X 4 . 6 4 . 4 4 . 2 4 0 3 . 8 3 . 6 - 0 . 5 0 . 0 0 . 5 1.0 1.5 2 0 2 5 3 0 3 5 4 0 4 . 5 W a k t u i n k u b a s i ( b u l a n ) G a m b a r 4 . P e r u b a h a n p H o s e t e l a h i n k u b a s i p a d a b u l a n k e 2 , 3 d a n 4 t a n a h T L U P e r l a k u a n d e n g a n b a t u a n f o s f a t d a n b o k a s h i s e k a m p a d i j u g a m e n u r u n k a n p H o t a n a h . F o s f a t d a p a t s e c a r a k h u s u s d i j e r a p p a d a p e r m u k a a n o k s i d a y a n g m u a t a n p e r m u k a a n n y a n o l , b a h k a n n e g a t i f ( U e h a r a d a n G i l l m a n , 1 9 8 1 ) . S a a t j e r a p a n f o s f a t t e r j a d i , t e r j a d i p u l a k o o r d i n a s i a n i o n d e n g a n p e r m u k a a n i o n l o g a m . M o l e k u l H 2 O d a n i o n O h y a n g b e r p i . n d a h k e i o n l o g a m d i g a n t i k a n o l e h i o n f o s f a t H 2 P 0 4 - ( V a n R a n s t , 1 9 9 4 ) . P e n g g a n t i a n m o l e k u l H 2 O o l e h i o n f o s f a t m e n g h a s i l k a n p e n g u r a n g a n m u a t a n p o s i t i f D e n g a n d e m i k i a n t e r j a d i p e n i n g k a t a n m u a t a n n e g a t i f d a n p e n a m b a h a n k a p a s i t a s t u k a r k a t i o n s e r t a p e n u r u n a n p H o ( H i n g s t o n et al., 1 9 7 2 ) . W a r m d a n U e h a r a ( 1 9 7 8 ) , m e n u n j u k k a n b a h w a p e n i n g k a t a n j u m l a h f o s f a t m e n y e b a b k a n p e n u r u n a n p H o s e c a r a l i n i e r d a n s e i r i n g d e n g a n i t u t e r j a d i p e n i n g k a t a n m u a t a n n e g a t i f . J e r a p a n f o s f a t d a l a m j u m l a h b e s a r p a d a p e r m u k a a n p a r t i k e l m e n y e b a b k a n t e r b e n t u k n y a m u a t a n n e g a t i f P e n g g a n t i a n g u g u s a q u o ( - O H 2 ) o l e h f o s f a t m e n g h a s i l k a n p e n g u r a n g a n m u a t a n p o s i t i f , s e h i n g g a m e n g h a s i l k a n m u a t a n
n e g a t i f . S e b a l i k n y a p e n g g a n t i a n g u g u s i i i d r o l c s i i ( - 0 H ) t i d a l c m e r u b a l i m u a t a n p e r m u k a a n . P a d a P t a n a h y a n g r e n d a h , p e n g g a n t i a n g u g u s a q u o d a n j e r a p a n P b e r p e n g a r u h t e r h a d a p m u a t a n p e r m u k a a n . J i k a p H o a d a l a h t i t i k k e t i k a j e r a p a n H " ^ s a m a d e n g a n O H " , m a k a p e n g g a n t i a n g u g u s a q u o a k a n m e n y e b a b k a n p e n g u r a n g a n p a d a t i t i k y a n g m e m b u a t O H " l e b i h d a r i p a d a H " ^ s e h i n g g a p H o m e n j a d i l e b i h k e c i l , s e p e r t i d i p e r l i h a t k a n p a d a G a m b a r 5 . -OH2 - OH -OH2 " 0 \ • OH HO OH OH2 - O H OH2 . 1- OH ' O(pHo) h O ^ ^ O - OH2 - O H -6 . 5 - 3 1-OH2 • OH2 h O - ^ ^ O H OH 2 f-OH »3 . 5 - 3 0{pHo/-PZC) G a m b a r 5 . S k e m a p e n u r u n a n p H o m e l a l u i j e r a p a n p r o t o n p e r m u k a a n o k s i d a F e a k i b a t f i k s a s i f o s f a t ( V a n R a n s t , 2 0 0 6 ) P e n u r u n a n p H o i n i s e c a r a u m u m d a p a t d i l a k u k a n d e n g a n m e n g g u n a k a n i o n b e r v a l e n s i t i n g g i y a n g a k a n s e c a r a k u a t a k a n t e r i k a t d e n g a n m u a t a n n e g a t i f p e r m u k a a n . A n i o n s i l i k a t d a n f o s f a t s e c a r a s p e s i f i k m a m p u t e r j e r a p p a d a p e r m u k a a n o k s i d a , s e h i n g g a m e n g h a s i l k a n p e n g u r a n g a n p H o . B a h a n o r g a n i k m e m p u n y a i p H o y a n g r e n d a h y a i t u s e k i t a r 4 ( B a e r t , 1 9 9 5 ) . T a n a h b e r m u a t a n v a r i a b e l y a n g d i t a m b a h k a n d e n g a n b a h a n o r g a n i k d a l a m j u m l a h b e s a r , a k a n m e n g a l a m i p e n u r u n a n p H o m e l a l u i j e r a p a n a n i o n o r g a n i k y a n g m e n u t u p i s e b a g i a n p e r m u k a a n p o s i t i f n y a s e h i n g g a a k a n l e b i h m e n i n g k a t k a n m u a t a n n e g a t i f ( G i l l m a n , 1 9 8 5 ) .
