KHOA HOC CONG NGHE
DAIXIH GIA S U Y GlAlVI D O PHI D A T TROIXIIi L U A T R £ I ^ D I A D A I M HUYEIXI THOAI SCmi, TilXIH AIXI GIAIXIG
Nguyin Hiiu Cudng^
TOMTAT
Muc tieu ciia nghien ciiu la danh gia suy giam d6 phi dat trdng liia tren dia ban huyen Thoai Son ung dung phuong phap danh gia da chi tieu tich hop vol GIS. Cac chi ti6u duo^ sii dung de danh gia suy giam do phi gom: Chua hoa, suy giam chat huu co' tong so (0M%), suy giam dung tich hap phu (CEC), suy giam nito tdng sd (N%), suy giam ham luong phdt pho tong sd (P205%) va suy giam ham luong kali t6ng so (K^0%).
Ket qua danh gia cho thay do phi dat chi bj suy giam nhe voi diSn tich 2.187,79 ha, chidm 4,66% dien tich tu nhien ciia dia phuong.
T u khba: Danh gia da chi Ueu, dat trdng Ilia, huyen Thoai Scm, suy giam dd phi
bien dang vdi luu lupng nude va luong phii sa do ve tii thupng nguon sdng Me Kdng ngay cang sut giam khien dp phi cua dat canh tac giam siit, tinh trang han man gia tang. Theo Nguydn Thi Phuong Dai va dong tac gia (2017), tinh An Giang cd dien tich dat hi suy giam dp phi la 113.061 ha, chiem 31,97% dien tich tu nhien.
Muc tidu cua nghien ciiu la danh gia suy giam dp phi dat trong liia tren dia ban huyen Thoai Son, tinh An Giang, gidp dia phuong tiep tuc theo doi, cd eac giai phap nhSm ban chd va cai thien dd phi nhidu trong tuong lai.
2. PHUONG PHAP VA TRtlW TH NGHIBU CUU 2.1. P h u o n g p h d p n g h i d n ciiu 2.1.1. Phuong pbap ddnh gia da cbi tiiu Phuong phap danh gia da chi tieu (MCE: Multi- Criteria Evaluation) dupe ap dung trong tdng hpp danh gia dp phi cua dat, d^t hi suy giam do phi.
Nghien ciiu nay su dung phuong phap so sanh c^p doi dupe Saaty (1980) phat tnen trong mpt quy trinh phan tieh thii bac AHP (Analytical Hierarchy Process - AHP). Tinh toan trpng sd cac tieu chi thong qua ma tran so sanh cap ddi, qua trinh tmh toan dp uu tien gdm 3 budic:
Budc 1: So sanh cap ddi dung de xae dmh tam quan trpng tuong ddi giira timg cap chi tieu. Ma tran so sanh \-^[a,) vdi a,j la miic do quan trong cua tieu chi i so vdi heu chi j , khi dd l/a,^ la miic dp quan trong ctia heu chi j so vdi tieu chi i.
Budc2:Tinh trong sd.
' Tnrang Dai lipc Tai nguyen va Moi truong thanh ph6 Ho ^^^ J ; T i n h ty sd n h a t q u a n CR.
Chi Minh
Email: [email protected] 1. MO DAU
Su suy giam nhanh chdng ve dp phi nhidu cua dat ed Uen quan den nhu cau luong thuc ldn do phat trien dan sd, tang cudng khai thac chat dinh duong cua dat tai cac vimg nong nghiep ma khong quan tam dung miic den viec duy tri dp phi nhidu bang each su dung phan bdn, tai che chat thai htiu co. Cac chinh sach phat tiien nong nghiep cung thudng dan ddn suy giam dd phi nhieu eiia dat va suy thoai dat (Lindsay C. CampbeU (1998).
Nhan thiic duoc van dd day, da cd rat nhidu cac nghidn cuu danh gia suy giam dp phi tren thd gidi cdng nhu Viet Nam. Amason, T. va dong tac gia (1982), Sanchez, P. A (2002) h-ong cac nghien ciiu ciia minh da chi ro suy giam dp phi dien ra manh me tai Trung My va chau Phi. Alfred E. Hartemink (2006) da cung cap mot khung phan tich dd danh gia suy giam dp phi cua dat. Nghien ciiu da chl ra rang suy giam do phi nhieu cua dat dtrpc coi la phd bidn a viing dat cao cua viing nhiet ddi, dac biet la a chau Phi can Sahara. Suy giam dp phi nhidu ciia dat cd the duae danh gia hang each su dung mot tap hpp cac thupc tinh tir cac thdi ky khac nhau tai cimg mdt dia diem hoac tit cac he thdng su dung dat khac nhau vdi cung loai d^t.
Chat lupng dat trdng trpt d ddng bang sdng Cuu Long dang giam sut do ca yeu td ngoai canh khach quan lan bien phap canh tac chii quan cua nong dan.
Sir cdng hudng giiia tinh trang bien ddi khi hau, nude
KHOA HOC CdNG NGH|
Sau khi tmh toan dupe hp trpng sd, tien hanh tinh toan chi sd thich hpp S, cho ttmg chi tieu theo cdng thii'c: S, ^ ! W.xXi
2.1.2. Phmmg phip xay dung ban do Nghien cthi sir dung cac cdng cu GIS chdng xep cac ldp thdng tm, xay dung dii heu tong hpp danh gia suy giam dp phi, phan tich xii' ly va thdng ke so lieu.
Ban dd nen dd thd hidn cac ndi dung la ban do ndn dia hinh he tpa dp VN-2000 vdi ty Id 1/25.000.
2.1.3. Pbuong phap ki thim
Cac ket qua phan tich ihuc nghiem sii dung trong nghidn cihi duoc kd thira tii "Du an diiu tra, danh gia thoii hda dat vdng dong bang sdng Ciiu Longphue vu qudn ly su dung dat ben virng"txen dia ban tinh An Giang do Trung tam Dieu tra, danh gia tai nguydn dat phia Nam thuc hien nam 2016 vol diSn tich dieu h-a 31.437,84 ha (chidm 80,01% tdng dien tich dat Ilia dia phuong). Dii lieu nen su dung de danh gia miic dp suy giam duae ke thira tir du hSu phan tieh dat tir chuong trinh "Diiu tra bd sung, chinh ly, xay dung bdn dd dat pbuc vu quy hoach ndng nghiip cac tinh dong bang sdng Cthi Long"ciia Bd Ndng nghiep va PTNT nam 2002 (do Phan vien Quy hoach va Thiet ke ndng nghiep midn Nam thuc hien).
Bang 1. Didn tich cdc loai d^t
2.1.4. Pbuong pbap dieu ti-a, phdng vdn Ddi tuong phong van la cac chuyen gia ed Idnh nghiem ttong hoat dong danh gia dat dai ve miic dp quan frpng gilia cac chi tieu nham xac dmh bd ti-png sd cac chi tieu nay ti-ong danh gia suy giam dp phi.
2.2. Trinh tu nghidn ciiu
Trinh tu cua nghien ciiu dua tren viec so sanh thdng tin ve dd phi dat trong qua khu va hien tai nhd ap dting phuong phap danh gia da chi tidu, duoc thd hien theo sa dd sau:
Hinh 1. Trmh tu thyc hidn ddnh gid suy giam dd phi 3. KFT QUA NGHIEN CUU
3.1. D a c d i ^ m tdi n g u y d n d^t vd t h u c t r a n g sii d u n g d a t t r d n g liia trdn dia b d n h u y d n TTioai S o n t r d n dia b d n h u y d n T h o a i S o n
Bon vi tinb: ha STT
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 T
Xa, thi tran TT. Niii Sap TT. Oc Eo TT. Phii Hoa
An Binh Binh Thanh
Dinh My Dinh Thanh My Phii Dong
Phii Thuan Tay Phii Thoai Giang Vinh Chanh Vinh Khanh Vinh Phu Vinh Trach Vong Dong Vong The dng dien tich
Tvle(%)
DAphilsaCP) Dat phu sa co tang loang 16 do vang (Pf)
6,8 183,81 1.805,58 1.940,79 1.835,32 535,12 2.414,17
33,36 1.248,08
464.61 1.037.11 1.127.92 2.069.19 536.43 2.467.77 1.166,31 18.872.37 48,29
Dat phil sa gley (Pg) 436,4 422,42 1.269,87 1.873,85 195,26 2,230,17
186,35 1.937,28
615,89 73,52 1,014,25 10.255,26 26,24
Dat phen (S) Dat phen hoat dong nong (Sfl)
18,32
0,2 18,52
0,05
Dat phen hoat dong sau (Sj2)
71,93 454,86 673,81 477,07 214,85 379,39 213,51 1.920,84 1.908,42 302,35 1.029.82 1.071,77 13,93 1.206,40 9.938,95 25,43
Tong 515,13 638,67 422,42 2.479,39 2.417,86 3.320.04 2.788,36 2.822,94 2.281,85 3.168.92 2.559,38 3.276,74 2.773,63 3.214,48 1.550,68 2.481,70 2.372,91 39.085,10
100,00 NONG NGHIEP VA PHAT TRIEN NONG THON - KY 2 - THANG 12/2019 111
KHOA HOC CONG NGHE
Tren dia ban huyen Thoai Son cd 2 nhdm dat chinh la dat phii sa (P) va dat phen (S). Dat phu sa cua huyen cd 02 loai chu ydu \k ddt phu sa cd tang loang 16 dd vang (Pf) va dat phii sa gley (Pg) cua he thdng song Ciru Long. Dat phen chu yeu la cac loai dat phdn hoat ddng, gdm: Dat phen boat dpng nong (Sjl) va dat phen boat dpng sau (Sj2).
Theo sd lieu thdng ke dat dai nam 2016, tren dia ban huyen Thoai Son cd 39.289,29 ha dat trdng lua Bang 2. Kdt qua rd sodt hi^n trang dien tich
(chiem 94,76% didn tich dat ndng nghiep va chiem 83,80% dien tich tix nhien), tap tiling nhidu b ckc xa Dinh My 3.343,12 ha, Vinh Chdnh 3.289,44 ha, Vinh Phii 3.234,99 ha, Tdy Phii 3.185.28 ha. My Phu Ddng 2.825,33 ha, Dinh Thanh 2.801,06 ha. Vinh Khanh 2.783,40 ha, Thoai Giang 2.578.67 ha. Toan bd dien tich dat trdng liia cua huyen la dat chuyen tidng liia nude 2-3 vu trong dd phdn ldn la lua 3 vu.
d^t trong Ilia trdn dia bdn huyfin Thoai Son Don vitinbiha_
sn
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17
Xa, thi tran TT. Oc Eo TT, Niii Sap TT. Phil Hoa
Phu Thuan Dinh Thanh Tay Phit Vinh Chanh Vinh Khanh Vinh Trach Thoai Giang
Dinh My Vong The An Binh Binh Thanh Vong Dong My Phii Dong
Vinh Phii Tong dien tich
Theo thdng ke dat dai 645,24 515,82 423,18 2.287,04 2.801,06 3.185,28 3.289,44 2.783,40 1.572,31 2.578,67 3.343,12 2.373,73 2.495,72 2.421,82 2.513,14 2.825,33 3.234,99 39.289,29
Theo k^t qua dieu tra cua du an
638,67 515,13 422,42 2.281,85 2.788,36 3.168,92 3.276,74 2.773,63 1,550,68 2.559,38 3.320,04 2.372,91 2479,39 2.417,86 2.481,70 2.822,94 3.214,48 39.085,10
Chenh lech ha 6,57 0,69 0,76 5,19 12,7 16,36 12,7 9,77 21,63 19,29 23,08 0,82 16,33 3,96 31,44 2,39 20,51 204,19
1,02
%
0,13 0,18 0,23 0,45 0,51 0,39 0,35 1,38 0,75 0,69 0,03 0,65 0,16 1,25 0,08 0,63 0,52
-.ii
Hinh 2. Ban dd hidn frang ddt trdng liia nam 2016 huydn Tho?i San thu tii ty \t 1:25.000 Tuy nhien, ket qua dieu tra, ra soat cudi nam 2016 cua du an xac dmh dien tich dat trdng lua cua toan huyen la 39.085,10 ha. So vdi sd heu thdng ke
dat dai nam 2016, dien tich du an xac dinh thap hon 204,19 ha. Nguyen nhan la do tren dia ban huydn vdn ton tai tinh trang chuyen mue dich dat liia nhung khong xin phep dac biet la chuyen sang dat nudi trdng thuy san, ddt d. Ben canh do, 3 xa (My Phii Ddng, Vinh Phii, Vpng Dong) do mdi do dac lai khu vuc dat nong nghiep nen cd su dieu chinh dien tich giua dat lua, dat giao thong, thuy lpi.
3.2. Ket qud ddnh gid suy giam dp phi dat trdng Ilia
3.21. Xdc dinb dien tich suy giam cho ding chi tieu
Chi tieu dupe sir dung de danh gia suy giam dp phi va miic dp suy giam dupe quy dinh tai Thong tu sd 14/2012/BTNMT bao gom: Chua hda, suy giam
KHOA HOC CONG NGHE
chat hiiu ca tdng sd (0M%), suy giam dung tich hap ham lupng kaU tdng sd (K20%). Ket qua phdn tich phu (CEC), suy giam nita tdng sd (N%), suy giam cac mdu dat duoc lay tren dia ban theo timg chi tidu hdm lupng phdt pho tdng sd (P205%) va suy giam duoc the hien tai bang 3.
Bdng 3. Didn tich dat bi suy giam do phi theo timg chi lidu Chi tieu
d a n h gia
D a t bi c h u a h o a (Suy g i a m
P H K C J
S u y giam c h a t hiiu c a t o n g s o
(0M%)
S u y g i a m d u n g tich h a p p h u
(CEC)
S u y g i a m n i t a t d n g sd (N«)
S u y g i a m h a m l u a n g p h d t p h o t d n g so (P20s%)
S u y g i a m h a m liKmg k a h t d n g sd (KjO%)
M u c d a n h gia K h d n g s u y g i a m S u y g i a m n h e S u y g i a m t r u n g b i n h S u y g i a m n a n g K h d n g s u y g i a m S u y g i a m n h e S u y g i a m t r u n g b i n h S u y g i a m n a n g K h d n g suy g i a m S u y g i a m n h e S u y g i a m t r u n g b i n h S u y g i a m n a n g K h o n g s u y g i a m S u y g i a m n h e S u y g i a m t r u n g b i n h S u y g i a m n a n g K h d n g s u y g i a m S u y g i a m n h e S u y g i a m t r u n g b i n h S u y g i a m n a n g K h d n g s u y g i a m S u y g i a m n h e S u y g i a m t r u n g b i n h S u y g i a m n a n g
K h o a n g bien d d n g (A)
< 0 0 - 0 , 5
> 0 , 5 - l
> 1
< 0 0 - 1
> l - 2
> 2
< 0 0 - 5
> 5 - 1 0
> 1 0
< 0 0 - 0 , 0 5
> 0 , 0 5 - 0 , 1
> 0 , 1
< 0 0 - 0 , 0 2
> 0 , 0 2 - 0 , 0 4
> 0 , 0 4
< 0 0 - 0 , 5
> 0 , 5 - l
> 1
Ky h i e u SgpHN S g p H , SgpH^
S g p H j S g O „ S g O , S g O , S g O , S g C „ S g C i S g Q S g C , S g N „ S g N i S g N j S g N j S g P „ S g P i S g P , SgPj SgK„
S g K , SgKj SgK,
D i e n tich h a 11.293,51 20.144,33 0,00 0,00 23.296,06
8.141,78 0,00 0,00 28.286,11
3.151,73 0,00 0,00 3.656,17
0,00 8.989,67 18.792,00 31.437,84 0,00 0,00 0,00 20.787,61
0,00 10.650,23
0,00
%
35,92 64,08 0,00 0,00 74,10 25,90 0,00 0,00 89,97 10,03 0,00 0,00 11,63 0,00 28,60 59,78 100,00 0,00 0,00 0,00 66,12 0,00 33,88 0,00 Ket qua phan tich cho thay, ddi vdi cdc chi tidu
ddt hi chua hda, suy giam chat hiiu ca tong sd va suy giam dung tich hap phu chi didn ra b miic do nhe vdi cac didn tich lan lupt la 20.144,33 ha, 8.141,78 ha va 3.151,73 ha. Trong khi dd, ddi voi cac chi tieu suy giam nita tdng sd vd suy giam hdm lupng kali tdng sd lai diln ra vdi mirc dp trung binh va nang vdi dien tich \an, lan luot la 27.781,67 ha va 10.650,23 ha. Hdm lupng phdt pho tdng sd khdng bi suy gidm tren dia ban trong thdd gian nghien cuu.
3.2.2. Xdc dinb trgng sd cic cbi tieu
Hau het cac chuyen gia dupe phdng van deu cho rdng, suy giam hdm lupng chat hiiu ca, chua hda vd suy giam dung tich hap phu cd tdc ddng ldn den suy giam dp phi dat do cdc chi tieu trdn ed anh hudng ldn den cdc tinh chat khdc ciia dat, boat ddng cua vi sinh vdt dat. Khi nhung chi tieu ndy bi suy giam ldm dnh hudng den kha nang cung cap chat dinh dudng cua dat va hoat dpng cua vi sinh vat dat. Cdc chi tidu vd hdm lupng N, P, K tdng sd trong dat so vdi cac chi tieu tren thi vai trd cua nd it quan trpng hon. Do do, nghidn ciiu xep thir tu uu tidn cae chi tieu anh huong den suy giam dp phi eua vimg nghien ciiu bao gom:
NONG NGHIEP VA PHAT TRIEN NONG THON - KY 2 - THANG 12/2019 113
KHOA HOC CONG NGHE suy giam ham lupng chat hiru co^ dat hi chua boa;
suy giam dung tich hap phu; suy giam ham lupng N tdng sd; suy giam ham luong P tdng sd va cudi cimg la suy giam ham lupng K tong sd. Tren co sd tdng hpp ma tran so sanh cae chi tieu anh hudng ddn suy
giam dp phi cua cdc chuyen gia, nghien ciiu d& xua ma tran so sdnh cac chi tieu suy giam dp phi tai bang 4. Ma ti-dn gdm cac hang va c6t cdc chi tieu, gia tn mdi 6 la miic dd quan trong hon cua chi heu theo hdng so vai chi tieu Iheo cpt ddi vdi suy g'aiTi dp pin.
Bang 4. Ma trSn so sanh tdng hop cac chi tidu anh himni> dirt ftfl nhi dat Chi tidu
OM CEC KCL N P2O5 K2O
OM 1 1/3 1/5 1/7 1/9 1/11
CEC 3 1 1/3 1/5 1/7 1/9
KCL 5 3 1 1/3 1/5 1/7
N 7 5 3 1 1/3 1/5
PjOs 9 7 5 3 1 1/3
K,0 11 9 7 5 3 1 Tren CO sd ma tran so sdnh cap ddi tinh duoc
miic dd quan trong cua cac chi tigu, qua trinh tinh toan dupe thuc hien theo 3 budc cua phuang phdp danh gia da chi tieu. Kdt qua vector trpng sd eua cdc chi tieu tdng hpp suy giam dp phi dat nhu sau:
[Ws,o; Ws,c; WS^H; WS,H; WS,P; W,,^] = [0,4723;
0,2582; 0,1373; 0,0721; 0,0383; 0,0219].
Vdi chi sd nhdt quan CR = 0,39% < 10%, bd ti-ong sd tren la can tim.
Bdng 5. Chi sd Ihich hpp cua cdc
3.2.3. XAy dung ban dP suy gidm dd phi dat tiSng lua tren dia ban huyin Thoai Son
Sau khi da xac dinh duae trpng sd cdc chi tieu danh gia thi viec tich hpp chiing cho ta chi sd thich hpp hay kdt qua cudi cimg. Tien hanh tinh todn chi sd thich hpp S; cho timg ehi tieu theo cdng thirc: S,
— HfW^" X,-, trong do W, la trpng sd mdi chi tidu duoc tinh d budc tren, X, la diem cua timg chi tieu.
Ket qua cho chi sd thich hgp d bang 5.
chi ti^u anh hudng ddn dp phi ddt Chi tieu
Dat hi chua hoa (Suy giam PHKCI)
Suy giam chat hiiu ca tdng sd (0M%)
Suy giam dung tich hap phu (CEC)
Suy giam nita tdng sd (N%)
Ky hieu SgpH„
SgpHi SgpH, SgpH, SgON SgO, SgO, SgO, SgC„
SgC, SgC, SgC, SgN,.
SgN, SgN, SgN,
Didm ciia chi hdu I (X) 0,05 0,15 0,30 0,50 0,05 0,15 0,30 0,50 0,05 0,15 0,30 0,50 0,05 0,15 0,30 0,50
Chi sd thich hap (S) 0,0069 0,0206 0,0412 0,0687 0,0236 0,0708 0,1417 0,2362 0,0129 0,0387 0,0775 0,1291 0,0036 0,0108 0,0216 0,0361
KHOA HOC CONO NGHE
Chi Udu Suy giam ham luang phdt pho tdng
sd (P,0,%)
Suy giam ham luong kali tdng sd (K,0%)
Kyhieu SgPN SgP, SgP, SgP, Sgl^M SgK, SgK, SgK,
Diem ciia chi tieu I (X,) 0.05 0,15 0,30 0,50 0,05 0,15 0,30 0,50
Chi sd thich hap (S,) 0,0019 0,0057 0,0115 0,0192 0,0011 0,0033 0,0066 0,0110 Sau khi cd dupe chi sd thich hop timg cap cua
cac chi tieu, tien hdnh chdng ghdp cdc ldp chi tieu tren ArcGIS, ta chia khoang chi s6 thich hpp S cho tong hpp suy giam dp phi dat nhu bang 6.
Bang 6. Phdn cap chi sd thich hop Miic dp suy giam dp phi
Khong suy giam Suy giam nhe Suy gidm trung hinh
Suy giam nang
Gia tri S,
< 0,075 0,075-0,175 0,175 - 0,275
> 0,275
Bang 7. Kdt qua tdng hop suy giam dd phi Miicdd
Khdng suy giam Suy giam
nhe Suy giam trung binh Suy giam nang
Dien tich (ha) 29.250,05
2.187,79 0,00 0,00
Phdn tram dign tich dieu
h-a(%) 93,04 6,96 0,00 0,00
Phan tram dien tich tu nhien (%)
62,38 4,66 0,00 0,00 Tir kdt qua tinh chi sd thich hpp cua cdc chi tieu
anh hudng ddn dd phi dat va phdn cap chi sd thich hpp xdc dinh dupe dien tich cho mdi miic dp suy giam dd phi dat (Bang 7).
Bang 8. Di^n tich ddt hi suy giam dp phi phdn theo don vi hdnh chinh
Ket qua ddnh gid suy giam dp phi cua huyen Thoai Son cho thay, dat trdng liia chi hi suy gidm dd phi nhe Id 2.187,79 ha, chidm 6,96% didn tich didu tra va 4,66% dien tieh tu nhien.
Don vitinb:ba STT
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17
Dan vi hanh chinh (xa/thi tran) Thi tran Niii Sap Thi tran Phii Hda Thi Tran OcEo
An Binh Binh Thanh
Dinh Mv Dinh Thanh Mv Phti Ddng
Phii Thuan Tay Phii Thoai Giang Vinh Chanh Vinh Khanh Vinh Phii Vinh Trach Vong Ddng Vong The Tdng cdng Tv le % dign tich dieu tra
Khdng suy giam dp phi 525,56 388,42 187,41 1.797.57 1.841,33 3.123,62 2.656,48 2.391,10 2.187,79 2.040,37 1,949,01 2.943,24 1.740,11 2.132,96 1.505,00 2.390,03 1.453,90 29.250,05 93,04
Phan mirc danh gia dat bi suy giam do phi Tdng sd
2.187,79
2.187,79 6,96
Nhe
2.187,79
2.187,79 6,96
Trung binh
0,00 0,00
Nang
0,00 0,00
Tdng dien tich dieu
h-a 525,56 388,42 187,41 1,797.57 1.841,33 3,123,62 2.656,48 2,575,04 2.187,79 2.040,37 1.949,01 2.943,24 1.740,11 2.132,96 1.505,00 2.390,03 1.453,90 31.437,84 100,00 NONG NGHIEP VA PHAT TRIEN NONG THON - KY2-THANG 12/2019 115
KHOA HOC CONG NGHE
hoach, khuydn ndng vd khuyen cao su dung ^ ti-dng Ilia hieu qua hon tren dia ban huyen Thoai Son.
TAI LIEU TKAM KHAQ
1. Alfred E. Hartemmk, 2006. Sofl FertiUty Declme: Definitions and Assessment. ISRlC-World Sod Information, Wageningen, The Netiierlands.
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3. Bp Ndng nghiep va PTNT, 2002. Du an Dieu tra bd sung, chinh ly, xdy dung ban do dat phue vu quy hoaeh ndng nghiep cac tinh ddng bang sdng Cliu Long.
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Hinh 3. Ban dd suy gidm dd phi huyen Tliojii Son thu tii ty 1^1:25.000
Nguyen nhdn suy giam dp phi, mat chat dinh duong Id do viec canh tac thdm canh, tang vu lien tuc trong san xuat, ddng thdi sir dung nhieu phdn hda hpc nhung khong sit dung carbon huu ca trong ram, ra bd sung cho dat, lam giam khd nang san xuat cua dat, ddc biet vimg trong de bao khep kin khdng cd luong phil sa bdi dap hdng ndm. Viec suy giam nghiem tipng ngudn nude lu hdng nam cung tac dpng rat ldn den su bdi ddp phii sa cho cac canh ddng ddn den dat hi suy giam dp phi.
4. KET LUAN
Ddnh gid su suy giam dp phi dat trdng lua tren dja bdn huyen Thoai Son, tinh An Giang giai doan 2002 - 2016 bang cdeh so sdnh thong tin ve do phi dat qua khu va hien tai sir dung phuong phdp ddnh gia da chi tieu cho thay dien tich dat bi suy gidm nhe Id 2.187,79 ha, chiem 4,66% dien tich tu nhien ciia dia phuong. Ddi vdi cac chi tidu dat hi chua hda, suy giam chat huu ca tdng sd va suy giam dung tich hap phu chi didn ra d miic dp nhe. Trong khi dd, ddi voi cac chi tidu suy giam nita tdng sd va suy giam ham lupng kali tong sd lai didn ra vdi miic dp trung binh va nang. Ham lupng phdt pho tdng sd khong hi suy giam. Ket qua danh gia suy giam dp phi se giup eho cac nhd khoa hoc, nha quan ly cd giai phap cai thien timg chi tieu cua do phi nhdm phue vu cong tdc quy
ASSESSING SOIL FERTILITY DECLINE OF RICE LAND IN THOAI SON DISTRICT, AN GIANG PROVINCE Nguyen Huu Cuong Summary
The objechve of this study aims to assess soil fertility decline of rice land at Thoai Son distnct by applying multi-critena evaluaUon (MCE) method integrated with GIS. The criteria which are used to assess decline of soil fertility include: soil pH, organic matter (0M%), cation exchange capacity (CEC), total nitrogen (N%), total phosphorus {P205%) and total potassium (K^O^). The evaluation results show that soil fertility is only slighdy reduced with an area of 2,187.79 hectares, accounting for 4.66% of the local natural area.
Keywords: Multi-critena evaluation, nee land, Thoai Son distnct, soil fertility decline.
Ngudi phan bien: TS. Dd Tnmg Binh Ngdy nhdn bdi: 3/6/2019 Ngdy thdng qua phan bien: 4/7/2019 Ngay duyet dang: 11/7/2019
