Tho Nhuong Dac Diem Hoa Hoc Cua Dat

7/31/2019 Tho Nhuong Dac Diem Hoa Hoc Cua Dat

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Thnh phn ha hcca cy trng v t


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1. Thnh phn ha hc v dinh

dng cy trng1.1. Thnh phn ha hc ca cy trng- Nc v cht kh.- Nc: l thnh phn ch yu trong cy

trng v c vai tr quan trng; chim 80-95%

- Cht kh: cht v c v hu c (phn cnli sau khi lm bay hi nc); chim 5-20%.


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94-96% H2O 86-91% H2O90-93% H2O75-80% H2O

18-22% H2O7-10% H2O

12-15% H2

O 12-15% H2O


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Cy trngt0(sy)

Nc Cht kh+

+ O2

Kh Tro+


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c im ha hc t

http://yeumoitruong.vn/forum/showthread.php?1954-Gi%C3%A1o-d%E1%BB%A5c-

m%C3%B4i-tr%C6%B0%E1%BB%9Dng-trong-tr%C6%B0%E1%BB%9Dng-h%E1%BB%8Dc
http://yeumoitruong.vn/forum/showthread.php?1954-Gi%C3%A1o-d%E1%BB%A5c-m%C3%B4i-tr%C6%B0%E1%BB%9Dng-trong-tr%C6%B0%E1%BB%9Dng-h%E1%BB%8Dchttp://yeumoitruong.vn/forum/showthread.php?1954-Gi%C3%A1o-d%E1%BB%A5c-m%C3%B4i-tr%C6%B0%E1%BB%9Dng-trong-tr%C6%B0%E1%BB%9Dng-h%E1%BB%8Dchttp://yeumoitruong.vn/forum/showthread.php?1954-Gi%C3%A1o-d%E1%BB%A5c-m%C3%B4i-tr%C6%B0%E1%BB%9Dng-trong-tr%C6%B0%E1%BB%9Dng-h%E1%BB%8Dchttp://yeumoitruong.vn/forum/showthread.php?1954-Gi%C3%A1o-d%E1%BB%A5c-m%C3%B4i-tr%C6%B0%E1%BB%9Dng-trong-tr%C6%B0%E1%BB%9Dng-h%E1%BB%8Dchttp://yeumoitruong.vn/forum/showthread.php?1954-Gi%C3%A1o-d%E1%BB%A5c-m%C3%B4i-tr%C6%B0%E1%BB%9Dng-trong-tr%C6%B0%E1%BB%9Dng-h%E1%BB%8Dchttp://yeumoitruong.vn/forum/showthread.php?1954-Gi%C3%A1o-d%E1%BB%A5c-m%C3%B4i-tr%C6%B0%E1%BB%9Dng-trong-tr%C6%B0%E1%BB%9Dng-h%E1%BB%8Dchttp://yeumoitruong.vn/forum/showthread.php?1954-Gi%C3%A1o-d%E1%BB%A5c-m%C3%B4i-tr%C6%B0%E1%BB%9Dng-trong-tr%C6%B0%E1%BB%9Dng-h%E1%BB%8Dchttp://yeumoitruong.vn/forum/showthread.php?1954-Gi%C3%A1o-d%E1%BB%A5c-m%C3%B4i-tr%C6%B0%E1%BB%9Dng-trong-tr%C6%B0%E1%BB%9Dng-h%E1%BB%8Dchttp://yeumoitruong.vn/forum/showthread.php?1954-Gi%C3%A1o-d%E1%BB%A5c-m%C3%B4i-tr%C6%B0%E1%BB%9Dng-trong-tr%C6%B0%E1%BB%9Dng-h%E1%BB%8Dchttp://yeumoitruong.vn/forum/showthread.php?1954-Gi%C3%A1o-d%E1%BB%A5c-m%C3%B4i-tr%C6%B0%E1%BB%9Dng-trong-tr%C6%B0%E1%BB%9Dng-h%E1%BB%8Dchttp://yeumoitruong.vn/forum/showthread.php?1954-Gi%C3%A1o-d%E1%BB%A5c-m%C3%B4i-tr%C6%B0%E1%BB%9Dng-trong-tr%C6%B0%E1%BB%9Dng-h%E1%BB%8Dchttp://yeumoitruong.vn/forum/showthread.php?1954-Gi%C3%A1o-d%E1%BB%A5c-m%C3%B4i-tr%C6%B0%E1%BB%9Dng-trong-tr%C6%B0%E1%BB%9Dng-h%E1%BB%8Dchttp://yeumoitruong.vn/forum/showthread.php?1954-Gi%C3%A1o-d%E1%BB%A5c-m%C3%B4i-tr%C6%B0%E1%BB%9Dng-trong-tr%C6%B0%E1%BB%9Dng-h%E1%BB%8Dchttp://yeumoitruong.vn/forum/showthread.php?1954-Gi%C3%A1o-d%E1%BB%A5c-m%C3%B4i-tr%C6%B0%E1%BB%9Dng-trong-tr%C6%B0%E1%BB%9Dng-h%E1%BB%8Dchttp://yeumoitruong.vn/forum/showthread.php?1954-Gi%C3%A1o-d%E1%BB%A5c-m%C3%B4i-tr%C6%B0%E1%BB%9Dng-trong-tr%C6%B0%E1%BB%9Dng-h%E1%BB%8Dchttp://yeumoitruong.vn/forum/showthread.php?1954-Gi%C3%A1o-d%E1%BB%A5c-m%C3%B4i-tr%C6%B0%E1%BB%9Dng-trong-tr%C6%B0%E1%BB%9Dng-h%E1%BB%8Dchttp://yeumoitruong.vn/forum/showthread.php?1954-Gi%C3%A1o-d%E1%BB%A5c-m%C3%B4i-tr%C6%B0%E1%BB%9Dng-trong-tr%C6%B0%E1%BB%9Dng-h%E1%BB%8Dchttp://yeumoitruong.vn/forum/showthread.php?1954-Gi%C3%A1o-d%E1%BB%A5c-m%C3%B4i-tr%C6%B0%E1%BB%9Dng-trong-tr%C6%B0%E1%BB%9Dng-h%E1%BB%8Dchttp://yeumoitruong.vn/forum/showthread.php?1954-Gi%C3%A1o-d%E1%BB%A5c-m%C3%B4i-tr%C6%B0%E1%BB%9Dng-trong-tr%C6%B0%E1%BB%9Dng-h%E1%BB%8Dchttp://yeumoitruong.vn/forum/showthread.php?1954-Gi%C3%A1o-d%E1%BB%A5c-m%C3%B4i-tr%C6%B0%E1%BB%9Dng-trong-tr%C6%B0%E1%BB%9Dng-h%E1%BB%8Dchttp://yeumoitruong.vn/forum/showthread.php?1954-Gi%C3%A1o-d%E1%BB%A5c-m%C3%B4i-tr%C6%B0%E1%BB%9Dng-trong-tr%C6%B0%E1%BB%9Dng-h%E1%BB%8Dc


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Thnh phn ha hc ca t

Cac nguyen to hoa hoc cha chu yeu trong phan khoang,

hu c cua at.

Nguon goc cua chung co t a va khoang tao thanhat.

Trong at co khoang hn 45 nguyen to khoang


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Nhng nguyn t ha hc ph bin trong vtri t (Gabler et al, 1991)

Nguyn t % khi lng % th tch

O 46,6 93,8

Si 27,7 0,9

Al 8,1 0,5

Fe 5,0 0,4

Ca 3,6 1,0Na 2,8 1,3

K 2,6 1,8

Mg 2,1 0,3


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S ha tan cc khong trong t Cac khoang hoa tan se giai phong dinh dng vao dung

dch at

Trong dung dch at, cac khoang hoa tan co the b ket tua

tr lai nh luat tac ong khoi lng

Hang so san pham hoa tan Ksp cang nho, kha nang hoatan cua khoang cang thap.

CaSO4 Gypsum Ksp = 1.95 x 10-4

Al(OH)3 Aluminum Hydroxide Ksp = 1.6 x 10-34


10/50

Cc khong ph bin trong t

Calcium Carbonate

Ksp CaCO3 = 0.87 x10-8

Aluminum Hydroxide

Ksp Al(OH)3 = 1.6x 10-34

Sat Hydroxide

Ksp Fe(OH)3 = 1.6x 10-37

pH la yeu to chnh anh hng en kha nang hoa tan cua cackhoang nay


11/50

Cht hu c ca t

soil organic mater (SOM) L thnh phn quan trng nht ca t, nh gi ph ca t Hp chat rat phc tap

Rat kho xac nh tnh chat hoa hoc

Qua trnh hnh thanh c kiem soat bi cac tien trnh

sinh hoc Rat bien ong

Rat nhay cam vi ieu kien moi trng


12/50

Thnh phn ca cht hu c

Sinh khoi

Re cay

Giun at va con trung

Vi sinh vat

D tha, xac ba

D tha thc vat ti (cha phan giai)

Bat au phan giai

Ban phan giai

Phan giai hoan toan

Mun


13/50

Cht hu c khng c trng

Chim 1015% tng sSOM ca t C ngun gc t:- ng thc vt: xc TV, VSV- Cc sn phm trung gian ca qu trnh phn

hy: protein, m, sp, celluloza, Khi phn hy gii phng cht dinh dng cho TV Kch thch hay kim hm sinh trng ca cy


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Cht mn

Acid humic

Acid fluvic

Humin


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Acid humic

Tnh cht ha hc C : 50 62% H : 2,8 6% O : 31 41%

N : 2 6% Ngoi ra cn c 1 - 10% :P, S, Fe, Al


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Acid humic

Tnh cht c bn Tnh acid thp It di ng, t b ra tri Kh nng hp ph cao

Lin kt vi khong st ca t to nnkeo phc v c hu c


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Acid fluvic

Thnh phn ha hc C : 40 52% H : 3,5 5,5% O : 40 48%

N : 2 4% Hm lng cc nguyn ttro t7 10% pH : 2,6 2,8


18/50

Acid fluvic

L acid hu c cao phn t cha nito hnhthnh trong mi trng chua, d tan trong

nc, acid, bazo Kh nng ngng t km, Di ng t giu acid fluvic: chua, ngho mn, cc

nguyn ttrong t d b ra tri didng cc mui fluvat d ha tan


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Humin

L t hp ca cc cht mn c cu tobi cc lin kt gia acid humic, acid fluvic

v cc khong st trong t Humin c mu en, khng tan trong dung

dch kim, bn trong t, cy trng khng

s dng c


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Vai tr ca cht hu c

Tham gia vo qu trnh to thnh t Ci thin tnh cht vt l t Kh nng trao i hp ph ion cao L ngun cung cp thc n cho cy trng


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Qu trnh phn gii cht hu c

Qu trnh khong ha cht hu c: phnhy hon ton SOM to ra cc sn phm

nh mui khong, CO2va H2O

Qu trnh mn ha: qu trnh phn giicht hu c thnh hp cht mn (hp

cht cao phn t, mu en)


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nh gi mn trong t

T l C/N : t l C/N cng thp th SOM,mn b phn gii nhanh

Loi t C/NVng 12 nu 9 Ph sa 12 Mn trn ni 16


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C/N > 20

Qu trnh mn ha > qu trnh khong ha

t ym kh, SOM phn gii chm C/N < 20

Qu trnh mn ha < qu trnh khong ha


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Trao i ion

S hap phu cac ion trong dung dch vi be mat keo at

mang ien tch

ien tch trong he thong phai luon luon can bang

Cac ions nay co the trao oi vi cac ions khac e

luon duy tr s can bang ien tch

Lc hap phu thay oi


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Trao i cation Xy ra trn keo in tch m. C 2 loi keo:- Keo v c

- Keo hu c- Keo hu c - v c


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Ngun gc in tch trn keo v c

Set silicate cau truc dang phien

T dien silica

Bat ien Aluminum Thay the ong hnh

Al 3+ thay Si 4+ trong phien t dien = tha -1

Mg 2+ hay Fe 2+ thay Al 3+ trong phien bat dien = tha -1

Dien tch be mat 10 800 m2/g keo set


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1. Kaolinite Al2Si2O3(OH)4

Kieu set 1:1. 1 t dien silica

va 1 bat dien aluminum

Rat t co thay the ong hnh


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Kaolinite

Lc lien ket rat chat nen khong the co dan e hut them

cation hoac nc gi nc, phan kem

CEC thap: 1 - 10 meq/100g (cmolc/kg)

Pho bien tren cac loai at feralit, at phu sa chua, at xam

bac mau tren phu sa co, at cat ven bien


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2. Set Mica (illite va vermiculite)

Kieu 2:1. 2 t dien silica xep

tren va di 1 phien bat

dien aluminum

Thay the ong hnh chu yeu

xay ra tren phien t dien, v

vay ien tch nam tren be

mat set, nen lc gi rat

manh.


30/50

Set Mica (illite va vermiculite)

CEC tng oi thap: 15 - 40 meq/100g (cmolc/kg)

Co nh K ien tch va kch thc

Pho bien tren at doc tu, phu sa.


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3. Set Smectite

Kieu 2:1. 2 t dien silica nam

2 pha cua 1 bat dien

aluminum

Thay the ong hnh xay rachu yeu tren phien bat dien,

v vay ien tch hnh thanh

mat trong cua set, nen mat

o ien tch mat trong thap

hn be mat ngoai cua set.


32/50

Set Smectite

Kieu set nay c goi la set trng n. Co the co ngot hay trng n rat

manh trong ieu kien kho, am: khi nc vao/ra trong khoang lien tang.

CEC cao: 80 - 120 meq/100g (cmolc/kg)

Khong pho bien tren cac loai at VN.


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So snh cu trccc keo


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Loai keo Interlayer Cation

Kich thc (m)Spacing (nm)Hut b mtKaolinite 0.1-5.0 0.7 5-15

Smectite


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4. Oxides ngam nc

Cac khoang set oxide ngam nc pho bien la: Fe va aluminum.

ay la cac loai khoang set rat quan trong tren at phong hoa manh

vung nhiet i.

ien tch tren cac khoang set nay khong hnh thanh do thay the ong

hnh nh trong set aluminosilicate dang phien.

ien tch hnh thanh do qua trnh ion hoa cac goc hydroxide trong

khoang. ay la ien tch phu thuoc pH.

Hydroxides la cac loai set co ien tch thay oi theo pH.


36/50

Keo hu c

Ch yu l keo mnnh acid humic,fluvic

Keo hu c v c:Keo hu c t tn ti

c lp m kt hpvi keo v c


37/50

Quy lut strao i cation Nhng ion c ha tr cng ln kh nng trao i

cng mnh

Al3+ > H+ > Ca2+ > Mg2+ > NH4+ = K+ > Na+

Nhng ion c cng ha tr: ion no c khi lng

cng ln th kh nng trao i cng mnhK+ > Na+ ;

Ca2+ > Mg2+


38/50

Quy lut strao i cation

Nhng ion c kch thc cng ln thkh nng trao i cng mnh

Nng ion trong dung dch cng lnth kh nng hp ph cng mnh

Nng trong keo t cng ln khnng khuch tn cng mnh


39/50

Strao i cation ca r cy

n t dip 1030ll/100 g r Song t dip 40100ll/100 g r


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Trao i anion

Nhng ion c ha tr cng ln kh nnghp ph cng mnh

Vi ion c cng ha tr, khi lng ln hnth kh nng hp ph ln hn

HPO42- > H2PO4- > SO42- > Cl-


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Nhng ion trong mi trng acid dngha tan

Al, Fe, Mn Do Al hp th PO4 AlPO4 khng ha tanTrong mi trng acid cy trng d b thiu

dinh dng


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Cc dng hp ph trong t Kha nang at hap phu cac ion va cac phan t cac chat khac nhau t

dung dch va gi chung lai goi la kha nang hap phu.

Khong phai tat ca cac muoi eu b at hap phu. S hap phu cua at

quyet nh o ph nhieu cua at.

Kha nang hap phu cua at phu thuoc vao thanh phan c gii, loai keoat, o xop

Cc dng hp ph:- Hp ph c hc

- Hp ph l hc- Hp ph ha hc- Hp ph sinh hc- Hp ph trao i


43/50

Hp ph c hc

La kha nang cua at gi lai cac hat vat chat nho nh xac

hu c, hat set, vi sinh vat.

ieu kien cua s hap phu nay la: Kch thc khe h be hn cac vat chat b hap phu.

Be mat at cang go ghe th s hap phu cang ln.

Hat keo b hap phu co ien tch trai dau vi be mat hat at.


44/50

Hp ph l hcLa kha nang cua at gi lai cac chat tren be mat hat keo nh

nang lng be mat. Co hai dang hap phu:

Hap phu dng nhng chat lam giam sc cang be mat cua

dung dch at bao quanh va lam tang nong o cac chat trenbe mat hat at. Cac phan t cua nhieu hp chat hu c

(ru, acid hu c, kiem va chat hu c cao phan t b hap

phu ly hoc dng.

Hap phu am nhng chat lam tang sc cang be mat ngoaicua dung dch at bao quanh va lam giam nong o cac chat

tren be mat hat at. Nhng ion Cl-, NO3de b ra troi do

nc.


45/50

Hp ph ha hc La kha nang cua at gi lai cac chat hoa tan dang ket tua hay tan t.

co nh nhng nguyen to co li cho cay trong nh: P, Ca, S ; tch luy cacchat trong at nh Al, Fe, S,

Cac ion Cl-, NO3-vi cac cation khac khong tao thanh, Cl-, NO3

-cotnh linh ong cao.

CO3

2- , SO4

2- vi cation hoa tr 1 tao thanh muoi hoa tan, con vication hoa tr 2 tao thanh hp chat kho hoa tan (vi Ca, Mg)

Cac anion photphat (H2PO4- , HPO4

2- ) vi cation hoa tr 1 taothanh muoi hoa tan, vi cation hoa tr 2 va 3 th khac nhau ve o hoa

tan. Vi cation Al, Fe, Ca, Mg tao thanh hp chat kho hoa tan.

Cng o hap phu hoa hoc phu thuoc vao loai at : at en < atxam < at potzon ong co < at o.


46/50

Hp ph sinh hc La kha nang sinh vat hut cation va anion trong at re cay tiet ra ion

H+ e trao oi chat dinh dng dang cation.

Vi sinh vat va re cay hut co chon loc nhng ion di chuyen trong at

e bien thanh nhng chat hu c khong b nc ra troi. Chung

hap phu t dung dch at nit va cac nguyen to khac va chuyenchung thanh cac hp chat hu c.

Hap phu sinh hoc ong vai tro quan trong trong viec chuyen hoa

phan nit trong at,

Cng o hap phu sinh hoc phu thuoc vao o am, o thoang kh,

tnh chat at, so lng va thanh phan hu c.


47/50

Hp ph trao iLa phan ng gia keo at vi ion trong dung dch at.

S hap phu ch xay ra khi keo at tch ien va co s chenh lech nong o

gia be mat hat keo va dung dch at bao quanh.

Hap phu trao oi ong vai tro quan trong trong cac qua trnh tho nhng,

quyet nh tnh chat ly hoa hoc cua at, phan ng, tnh em cua at,

ac biet co y ngha khi tac dung at vi phan bon.


48/50

Hp ph trao i

Viec bon vao at phan hoa tan (N, K) mc o ln b hap phu trao oi.

Moi loai at trang thai t nhien cha mot so lng nhat nh cation hap

phu trao oi: Ca2+, Mg2+ , H+ , Na+ , K2+, NH4+, Al3+

Trong a so cac at chiem u the la Ca2+, sau o la Mg2+ trong thanh phan

cation trao oi.

at chua cha lng ln H+


49/50

Phn ng oxy ha kh ay la phan ng xay ra pho bien trong at, gi vai tro quan

trong oi vi o ph nhieu cua at.

co s tham gia cua vi sinh vat.

dung e anh gia o thong kh va kha nang cung cap dngchat trong at.

ien the at cay trong can tot nhat la 200 700mV, neu cao

hn th mot so chat chuyen sang trang thai oxyhoa khong hoa

tan, nen cay khong hut c dng chat. Neu qua thap se

gay oc cho cay v sinh ra chat H2S


50/50

Phn ng oxy ha kh

Bien phap ieu chnh ien the oxy hoa kh:

Rut nc phi ruong,

pha vang sau khi ma hoac ti,

lam co, cay ai, ba ky.

Bon phan hu c va bon voi e cho at ti xop.

pH at va cac tnh chat i cung vi pH at co anh hng rat

ln en kha nang hu dung cua cac chat dinh dng oi vicay trong va o ph nhieu cua at.

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Tho Nhuong Dac Diem Hoa Hoc Cua Dat