I HC QUC GIA THNH PH H CH MINH TRNG I HC KHOA HC T NHIN KHOA MI TRNG 10KMT

C S MI TRNG T TI

T XMGVHD: Ths. Nguyn Trng Ngn Nhm thc hin: nhm 5 1. Trng Tm Chung 2. H Th M Li3. Ng Ngc Ngn

1017031 1017152 1017169 1017172 1017184 1017196 1017202

4. Nguyn Th Kim Ngn 5. Nguyn L Phng Nguyt 6. Phan Minh Nht 7. on Ngc Qunh Nh

t xm

Nhm 5

8. Hunh Phan 9. Trn Hng Phc 10. Nguyn Th Thanh Thy 11. Nguyn Trn Kim Xun

1017205 1017211 1017280 1017347

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MC LCMC LC...................................................................................................................................3 Cc n v t...................................................................................................................10 t xm bc mu (Xb) - Haplic Acrisols (ACh).............................................................10 Cu to phu din: ...........................................................................................................11 t xm c tng loang l (Xl) - Plinthic Acrisols (ACp)..............................................13 t xm gly (Xg) - Gleyic Acrisols (ACg)...................................................................15 t xm Feralit (Xf) - Ferralic Acrisols (ACf)................................................................17 t xm mn trn ni (Xh) - Humic Acrisols (ACu)......................................................27 THOI HA.............................................................................................................................29 TI LIU THAM KHO..........................................................................................................33

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I.

GII THIU CHUNG t xm (acrisols) bao gm nhng loi t xm thc s v t loang l vng, pht trin trn nn ph sa c, k c t bc mu do qu trnh ra tri t xm lm tch t tng th 2 cc oxit kim loi kim v kim th. t xm l loi t km mu m, phu din ton ct, thnh phn c gii t ct pha n tht nh nn t c mu xm. Nhm t ny rt ph bin vng i ni, ngoi ra cn gp vng gip ranh gia i ni vi ng bng (vng bn sn a) v vng ph sa c. Phn b ch yuo

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ng bng sng Hng: Bc Ninh, Bc Giang, Vnh Phc, Ph Th, ngoi thnh H Ni. ng Nam B: Long Thnh, Vnh Cu, H Nai, TP.Bin Ha, Nhn Trch ( ng Nai ); Bn Ct, Tn Uyn, th x Th Du Mt; Bnh Long, ng Ph (Bnh Phc ); Hc Mn, G Vp, Qun 12, Tn Bnh, Qun 1, Qun 3, Bnh Tn, Bnh Chnh, C Chi (TP.H Ch Minh ); G Du, Trng Bom, Trng Bng, Dng Minh Chu, Ha thnh, Bn Cu. Tn Bin, Chu Thnh (Ty Ninh ), B Ra - Vng Tu. Ty Nguyn gp pha Ty Bc Bun M Thut c Lc

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C din tch ln nht nc ta, vi tng din tch: 19.970.642 ha. Chim din tch ln nht, nhng kh nng canh tc ca t xm li rt hn ch. Do , vic nghin cu v tnh cht, vic s dng v ci to t xm l rt cn thit.

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II. NGUN GC-

Do cc acid nhiu ct sinh ra (hoa cng, cm thch, sa thch, trng thch).

Hoa cng: Thnh phn chnh l SiO2 (72.04%) Cm thch:C s mi trng t Trang 4

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Thnh phn ch yu l canxit (dng kt tinh ca cacbonat canxi, CaCO3). Sa thch ( ct kt): Thnh phn gm cc ht ct ch yu l fenspat v thch anh c gn kt bi xi mng silic, canxi, oxit st... Trng thch (Porphyry): mc ma bao gm nhiu ht ln ca nhng tinh th, chng hn nh Quartz hoc Feldspar. Quartz: SiO2 Feldspar: Kali, natri hoc Calci hoc hn hp nhng nguyn t ny.

III.-

HNH THNH t xm c hnh thnh v pht trin trn nhiu loi m khc nhau nh phin st, bin cht, granit, macma Cc qu trnh hnh thnh t xm: vng gip ranh gia ng bng v trung du min ni, a hnh dc

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thoi. Ni y, qu trnh ra tri cc ht keo, st, cht dinh dng din ra mnh m, phong ha t thnh t xm. Cc qu trnh tch lu Fe, Al; tch lu cht hu c v mn, ho chua. S khai thc rng trng trt nhng vng nhit i thng dn n s thoi ha t v lm gim ph nhiu. Trng la lu i vi tp qun canh tc lc hu.

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t xm trn nn ph sa c: Ph sa c c hnh thnh trn ng bng chu th sau c nng ln. Tri qua qua cc qu trnh phong ha ph sa c hnh thnh nn t xm ngy nay. Cc qu trnh phong ha bao gm: Qu trnh ra tri: do lng ma ln nn qu trnh ra tri cc cht khong v hu c din ra mnh m. Cc qu trnh tch ly: Qu trnh to khong st kaolionit vo ma ma

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KalSi3O8 + 2H+ + 9H2OAl2Si2O5(OH)4 + 4H2SiO4 + 2K+ Vo ma kh cc ion ca Fe tri ln ri b cc dung dch t hp th. Qu trnh tch ly mn. Nh sinh vt sng trong t to nn lp mn cho t nhng do tc ra tri qu ln nn lng mn trong t cn li rt t.

IV. TNH CHT CHUNG 1. L tnh-

Vt liu c mu nu vng, gn ln n mt chuyn sang mu xm. a. Thnh phn c gii

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t xm ni chung c thnh phn c gii nh (ct pha, ct)

- C t l cp ht trung bnh v mn t 40-45%, cp ht st chim 20-25% v c s gia tng st theo chiu su. b. Thnh phn khong st: Kaolinit l ch yu. Trong t xm ng mn cn thy Vermiculit vi s lng t.-

Thnh phn khong st ny lm cho kh nng hp th trao i cation km. Cng vi lng mn tng mt thp, t l st thp nn t xm d b ngho dinh dng trong qu trnh canh tc.

c. Dung trng ca t t c cu trc km, d b cht. Dung trng t 1,44g/cm3 t rng n 1,53 g/cm3 t trng cao su.-

d. Kh nng gi nc: Km, do thnh phn c gii nh

- tr m cc i lin quan ti hin trng s dng t, nhng ni c thm canh hay cn rng th kh nng gi nc kh hn.

Loi t AcrisolsC s mi trng t

su 0 20

Dung trng (g/cm3) 1,01 1,55

T trng 2,56 2,83

xp (%) 41,1 64,3Trang 6

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(t xm Feralit trn phin thch st) Acrisols (t xm Feralit pht trin trn gnai) Acrisols (t xm Feralit pht trin trn ph sa c)

20 40 40 60 60 80 80 100 0 20 20 40 40 60 60 80 80 100 0 15 20 60 60 100

0,94 1,48 1,25 1,49 1,25 1,56 1,27 1,63 1,05 1,43 1,24 1,30 1,35 1,36 1,20 1,31 1,30 1,31 1,08 1,55 1,52 1,78 1,40 1,76

2,64 2,88 2,64 2,75 2,64 2,72 2,65 2,70 2,65 2,73 2,69 2,70 2,67 2,73 2,69 2,74 2,69 2,74 2,62 2,64 2,65 2,70 2,58 2,73

61,7 67,4 41,7 53,2 40,9 53,7 39,5 51,9 46,3 59 49,4 54,0 49,4 52,8 51,0 55,0 52,0 52,8 41,0 58,7 32,8 43,7 33,3 48,7

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Loi t Acrisols (Vng pht trin trn gnai) Acrisols (Nu vng trn ph sa c) Acrisols (Trn vi)

su (cm) 0-20 20-40 40-60 60-80 80-100 100-150 0-20 20-40 40-60 60-80 80-100 0-20 20-40 40-60 .

% theo trng lng Nc ht m m ho tr m (Why) cy cc i 12,6 19,3-31,3 35,0-38,0 13,5 19,2-23,4 30,9-35,7 14,1 22,1 36,6 14,5 21,5 36,2 15,0 23,9 36,7 14 22,6 35,8 6,2-9,7 9,1-16,0 25,0-36,0 6,4-10,0 10,4-16,7 21,0-34,0 6,6-11,0 10,7-18,0 26,0-36,0 7,0-11,0 12,3-21,0 26,0-37,0 8,0-12,0 17,6-23,0 26,0-38,0 18,9 22,4-30,0 30,2-40,0 21,2 23,8 29,6 22,5 25,7 30,0

Phm vi nc hu hiu 15,7-16,9 7,5-16,5 14,5 14,7 12,8 13,2 16,0-20,0 11,0-17,0 15,0-18,0 13,0-16,0 9,0-5,0 7,8-10,0 5,8 4,3

2. Ha tnh-

y l nhm t c tng B tch st (Argic) vi dung tch hp thu di 24mc/100g st v no baz di 50%, ti thiu l mt phn ca tng B ca lp t 0-120cm, khng c tng E nm t ngt ngay trn mt tng c tnh thm chm. Lng hu c thp. t chua, pH t 3 4.5. Kh nng trao i cht km. Qu trnh khong ha cht hu c rt mnh lit. Trong vng mt nm vi m 80 85%, nhit 35 37oC, khong ha hon ton cc xc b ng thc vt. Qu trnh mn ha li rt chm, v cht hu c trung gian rt t. M nguy c ra tri lun thng trc nn tng lng mn v cc acid mn rt thp, nu c mn th li ch yu l acid fulvic, rt t acid humic. Qu trnh laterite li thng xy ra khi v tr v iu kin d dng tch ng trong cc tng nc ngm, nng m li hay tri st theo ma.Trang 8

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t xm

Nhm 5

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Qu trnh xi mn lun xy ra vng t xm trin i. Ngc li, qu trnh tch ng mn th cc cht ra tri t trin i xung vng trng, thung lng ca cc loi t xm tch ng, gley.

3. Sinh tnh

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Do iu kin dinh dng v kt cu t, hot ng ca vi sinh vt v ng vt trong t rt km.

V. PHN LOI Trong bng phn loi t 1996, nhm t xm c 5 n v: - t xm bc mu in hnh (Xb) - t xm c tng loang l (Xl) - t xm gly (Xg) - t xm Feralit (Xf) - t xm mn trn ni (Xh) - Haplic Acrisols - Plinthic Acrisols - Gleyic Acrisols (ACg) (ACf) (ACu) (ACh) (ACp)

- Ferralic Acrisols - Humic Acrisols

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Cc n v t t xm bc mu (Xb) - Haplic Acrisols (ACh)

Din tch: 1.791.021 ha Phn b: t xm bc mu ch yu pht trin trn t ph sa c, macma axit v ct, gp trung du v min ni pha Bc, cc tnh min Trung, Ty Nguyn, ng Nam B. Mu cht v m gm ph sa c, ct v macma axit (granite) Lp t trn mt (tng canh tc) c mu trng hoc xm trng l tng c trng ca t xm bc mu, tng ny cn c tn gi l tng bc mu. Tng bc mu c thnh phn c gii nh, kt cu km hoc khng c kt cu, rt ngho cc cht dinh dng, chua v thng b kh hn.

Tnh cht t Tnh cht vt l: t c thnh phn c gii nh, dung trng 1.30-1.50g/cm3. t trng 2.65-2.7 g/cm3. xp 43-45%. Sc cha m dng rung 27-31%. m ho cy 5-7%. m hu hiu 22-24%. thm nc lp t mt 68mm/gi. Lp t su 25mm/gi Tnh cht ha hc: Phn ng ca t chua va n rt chua( pHKCl ph bin t 3,0- 4.5), ngho cation kim trao i( Ca2++Mg2+< 2mc/100g t). no baz v dung tch hp ph thp. Hm lng mn tng t mt t ngho n rt

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ngho( 0.5-1.5%). Mc phn gii cht hu c mnh( C/N