ĐÁNH GIÁ ẢNH HƯỞNG CỦA ĐIỀU KIỆN KHÍ HẬU NÔNG NGHIỆP ĐẾN CÂY TRỒNG NGẮN NGÀY Ở KHU VỰC NINH THUẬN VÀ BÌNH THUẬN

35(4), 364-373

Tap chi CAC KHOA HQC V£ TRAI S A T

©ANH GIA ANH HU'ONG CUA DIEU KIEN KHI HAU
^ NONG NGHIEP DEN CAY TRONG N G A N N G A Y
d KHU VUC NINH THUAN VA BINH THUAN
PHAM QUANG VINH', NGUYEN THANH BINH', BUI TH| THANH HU'ONG^
E-mail:
' Viin Dia Ly. Vien Hdn ldm Khoa hgc vd Cong nghe Viet Nam
Tru&ng Cao ddng Suphgm Hd Ngi
Ngay nhan bii: 10 - 9 - 2013
1. Mddau

Ninh Thuin va Binh Thuan la hai tinh nam d
cue Nara Trung bfl Vift Nam, cd tdng dien lich
khoang I1.165km^, vdi 350km dudng bd bifln
{hinh 1). Khu vgc nay dugc dac trung bdi khi hau
am va bin khd ban, cd khoang gin ragt nua difn

tich li khd ban vi ban khd han, do do diy Ii khu
vuc hing nam da va dang pbii ddi difln vdi linh
Irgng thieu nudc keo dii, cd khoing 6 din 9 thing
khd moi nim (lugng mua dudi 100mm). Noi day
ciing chju inh budng eua diflu kien nhift dfl cao vi
gid manh, li nhdng yeu td gdp phin thiic day qua
trinh ban ban, hoang mgc bda.

Ch6 giii
Khu VV6 nglMfl cthi
Ranh gidi Huy^

I

|mnnfli»illnh

Hinh 1. Khu v ^ nghifin


Cac hi?n tugng bgn ban v i hoang mgc hda dang
ngiy mflt lan rflng, d i e biflt trong bdi cinh bifln dfli
khi hgu, d i l i m i n h hudng ldn d i n vin dfl phat
trifln kinh te x i hgi, nhat l i san xuat ndng nghidp.
Ndng nghiep l i nganh kinh tfl chiu inh hudng
va phg thugc nhieu vio c i c yflu td tu nhien, die
biflt d cic nudc ngheo nhu Viflt Nam. Vi vgy, diflu
chinh sin xuat nflng nghiflp, ban ehe dugc nhung
tic dgng tieu cgc cua thifln tai, su dgng hiflu qua,
hgp ly tii nguyen l i mgc tiflu cua cac nhi khoa
hgc, nhi quin ly, n h i sin xuit tu xua den nay. Tuy
nhien, d Viflt Nam hien nay, cac nghifln cuu vfl van
dl nay mdi chi dirng lgi d nhQng danh gii dinh tinh
(phan tich nguyfln nhan va dfl xuit giai phip thich
urng), ma ehua dinh lugng dugc nhiing tic dgng
cua cic nhin td lu nhifln.
Trfln the gidi hifln nay d i cd mdt sd cdng bd
trong viflc Iugng bda dugc nhirng tie dflng niy.
Nhdm cic nha khoa hgc ciia trudng Dai hgc
Leuven (Bi) v i GS. Dirk Raes [1] da xiy dung he
thdng nhiing phan mem xu ly cic dii liflu khi tugng
nhim dinh gia anb budng ciia dieu kifln khi hau
den sin xuil ndng ngbi?p trfln co sd sir dung cic

thu^t toan, trong dd rad hinh Budget la md hinh
dugc ling dgng rgng rai trong tinh toan ein bing
nudc v i ude tinh raiic suy giira nang suat ciy
udng Iheo phin tram. Do dd vifle sii dung mo hinh
Budget xii ly cic dii liflu khi tugng ngiy dfl linh
toin can bing nudc phgc vg dinh gia tinh Irang
khd hgn doi vdi mflt sd ciy trdng ngin ngiy d tinh
Ninh Thuin v i Binh Thuin, nhira dua ra kit qua
vl miic dg suy giim ning suit ciy trdng (theo ty lfl
%) li ling dgng bit siic cin thilt. Kflt qui nghien
cuu niy li ca sd khoa hgc eho cie nha quin ly bfl
Iri diay dfli co ciu miia vg, thiet kfl c i y trong Ihieh
img vdi hgn ban, hoang mgc hda va bifln ddi
khi h^u.
2. Phuvng p h i p va dii' li^u nghien eiru

thoii nang suit trong giai doan cay trdng cin thiflt
nudc nhit [3].
MLFC dg suy giam ning suit cua cdy bdng
ndng nghiflp
Dinh g i i miic suy giim ning suit cay trdng
thuc tfl so vdi diflu kifln tfli uu dya tren phuong
phap ciia Jenssen (1968) [2], Iheo cdng thuc (I):

=n(:

CTnrtj

i«

STc^QpJ

w

Trong do: Ya: li nang suit thuc te;
Ym: li nang suit cao nhat (diflu kien trdng toi
uu);
ETact): la lugng bdc hoi nudc thuc tfl trong giai
doan i;
Etcrop,: lugng bde hai nudc khflng bi bgn che
ve dieu kifln trong giai dogn i;
X li chi sd nhgy eim Jensen dugc tinh theo
phuang Uinh do Kipkorir (2002) [3] dua ra trong
cdng thirc (2). Khi gin bai ky g i i Iri Ky nio sfl
cdX:
i, = (i.:75Jiiy' -El.l35lA"y= -f0,eJ61ii)-- 0,0137

R- = 0.99 (2)

Du lieu dau vao eua md binh Budget bao gom:
- DO' liflu khi tuvng: dii liflu mua ngiy v i dg
bdc thoal hai nudc hi 2 trgm khi hrgng Phan Rang
va Phan Thiet (cd tham khao va bd xung Ihem dd
liflu cua 4 tram Nba Trang, Vung Tiu, Xuin Lflc,
Bio Lflc). Hai tram khi tugng nay dgc trung cho
kiflu khi hau bin khd ciia khu vgc nghifln cim.
- DO li$u cay trong: bii bio lap trung nghien
ciiu cbo mgt sd ciy trdng ndng nghiflp ngin ngiy
(nhu: ngd, diu,...) la nhQng loai ciy phd bien tgi
khu vgc nghien cuu, Nhin chung, day la loai cay

trong cd Ihdi gian sinh trudng dudi 120 ngiy, cd
chieu dii re tfli da li 60cm va chju hgn vira phii.

2,1. Phuang phdp nghiin curu
De dinh gii miic dfl suy giam ning suit ciy
u i n g ngin ngiy, trong nghien cuu niy chiing tdi
sii dgng md hinh Budget kit hgp vdi viflc phan tich
cic da ligu khi biu ndng nghiflp. Md hinh Budget
li mgt phan m i m bao gom mgi tgp hgp cic chuong
trinh con md phdng c i c qui trinh hap thg nudc ciia
re ciy v i sg v$n chuyen nudc Irong eac ldp dai.
Bing cic phflp do nhiing y l u td inh hudng dfln
ning suit ciy trong, nd cd thi ude linh dugc sg suy

- DO liflu thd nhu-dng: cac tinh toan d i dugc
thgc hifln doi vdi 2 logi dit tuang phan, cd kha
nSng thoii nudc tdt v i khi phd bifln d khu vgc
niy la:
+ Dit set: d i y la logi dil m i ket ciu cd 3 ting,
bao gom: ting cat pha set (0-20em); ting miin cit
pha set cd dfl day 20-lOOcm; v i ting set pha cat cd
dg diy 100-200cm. Kiflu dil niy li logi dat dien
hinh cho cac nhdm dit dd v i xim (Ferralsols vi
365


Acrisols). Day la nhimg loai dat thoit nudc tdt vi
phfl bien biu het d viing niii va ddng banOg
ven sdng.
+ Dit cit: mflt ling cd ket ciu cat diy tren

20cm, mflt ting cat pha set cd dd day 20-200cm.
kieu dat niy dac trung cho cic loai dit cat
Arenosols Ihudng dugc tim thay dgc bd bifln khu
vgc nghifln ciiu.
Thdi gian bit diu gieo trdng dugc tinh tir diu
thing 5.
- Lu-gng bdc thoat hai nudc tiem nang (ETo):

Bdc thoii hai nudc Ii su kflt bgp giua do bdc
boi nudc ciia dit va dd thoat hai nudc eua ciy
trdng, Lugng bdc thoat hai nude chiu inh hudng
trgc tiflp tir cic thdng sd khi tuang, linh chat cay
trdng, sg cham sdc va diflu kifln mdi trudng, nfln
viec do dac Iugng bdc thoat bai nudc ngoai thgc te
li rat kbd khan De thuan Iai, ngudi la thudng tinh
lugng bdc thoai hai nudc tir rapt bflragtthara chieu
(beragttham chieu la mdt bfl mat trdng cd, bfl mat
niy bao gdra toan bo dac diflra eua dat, diflu kien
tudi nudc tdt va dieu kien ndng nghiep tdi uu),
Lugng bdc thoat hoi nudc tinh tir be rail nay dugc
goi la Iugng bde tboai hai nudc tham chieu va
dugc ky bieu li ETo.
Cong thirc tinh lugng bflc thoat boi tham chieu
ETo theo phuong phap FAO Penman-Monteith [I]:

Hi(c,-e.l

0.408A(/e„-G) + / ET--

2^3

A-(-?'(l + 0.34Uj)

(3)

Trong dd: ETo dO bdc - thoit hai nudc Iham
chiflu [mm/ngiy]; Ro la biic xg tai bfl mgt cay Irdng
[MJ/m^ngiy]; G ty trgng ludng nhiflt dit
[MJ/m^ngiy]; T nhiflt dg khong khi tgi dd cao 2m
[C°]; U2 tdc do gid tgi dg cao 2m [nVs]; e, ap suat
hoi nudc bao hda [kPa]; ejip suit hai nudc th\rc tl
[kPa]; Cs-Ca mirc dg thieu hgt ip suat boi nudc bao
bda [kPa]; A slope vapour pressure curve [kPa/°C];
Y thdng sd psychrometric [kPa/^CJ.
Mdt trong nhung md binh uu vi^l di dugc FAO
edng nhin dfl tinh dg bflc thoit hai nudc Iham
chiflu la phin mim ETo calculator [I].
Mdt nhin td nQa cd anh hudng rit ldn dfln nang
suit cay trdng, dd la miia mua va chieu dii Ihdi
gian im udt.
Theo dinh nghla ciia FAO chilu dii thdi gian im
udt dugc dua ra nhu li mgt thdi gian mi lugng mua
ldn ban lugng boc thoit hai nudc (hinh 2). Chiflu
dai ciia miia gieo trdng dugc dinh nghTa li thai gian
trong mdt nim khi lugng mua vugt qua mflt nua
lugng boc thoit hoi nudc tiem ning. Die diem niy
duge su dung de xac dinh dd dai chu ky vi ljch gieo
trdng vi viflc xic djnh diing thdi gian gieo trlng anh
huong trgc tiflp dfln ning suit miia vg>

Hinh 2 Chieu dai thwi gian am u61

Trong nghien cuu nay, chiing tdi di thuc hien
tinh toan chiflu dai thdi gian am udt trfln ca sd du
liflu dekad (1 dekad bang 10 ngiy) bang nam. Su
khdi dau cua thdi ky ara udl dugc xac dinh tai
ngay dau ciia 1 dekad khi ma lugng mua ldn ban
do bde thoat boi nudc vi khdng nhiflu han 1 dekad
khd. Thdi gian ket tbiic cua thdi ky im udt la ngiy

cudi cung cua dekad am udt mi sau dd cd it nhit 2
dekad lien hep kho.
2.2. BO- lifu su- difng
Dii lieu tu 6 trgm khi tugng quanh khu vgc
nghifln cim (Nha Trang, Phan Rang, Phan Thiet,
VQng Tail, Xuan Lflc, Bao Lgc) do Vifln Khi tugng


Thiiy vin vi Mdi trudng Vi^t Nam cung cap. Bg
du U^u bao gom nhi^t dg khong khi (tdi da vi Idi
thieu), dg am khdng khi (tdi thiflu va trung binh),
thdi ^an chieu sing, tdng lugng mua ngiy va tdc

dg gid Idi da. Trong nghifln cdu nay chiing Idi chii
yeu sii dung dii lieu ve nhiet do, dd am khdng khi
vi lugng mua ngay. Bdng 1 li dii liflu dugc idng
hgp tbeo gia tri trung binh nhieu nam.

BAng 1. DCr lifu cua 6 tram khi tiryng dirge sO dung cho nghien ci>u
Nhi$l dO

Bdo LOc
Nha Trang
Pttan Rang
Phan Thidt
VOng tiu
Xuan L9c

LAn
nhdt
28
30
32
31
31
32

Db im khOng khi%)

Nhd nhdt Trung binh
IB
24
24
18
29
22

56
76
71

79
79
78

Nh6
41
63
49
59

Mira Ining binh rh
N
Nam khA
2195
803
449
784
931
1652

Trung binh
2949
1266
636
1142
1490
2076

Nam am
5262

2552
1332
1768
1970
2597

Kilu khi h|lu
quan b ^ )

Am

30
28
28
26
26
18

Ban kho
Kho - ban am
Banlm
Banim
Am

ChO thich: (-) Id Ihi^u dO li$u

Sau trgm khi tugng phin bd deu xung quanh nghiflp. 0 nghien cuu niy chiing tdi tap trung phin
hai tinh Ninh Thuan vi Binh Thuin (hinh 3), Irong lich dQ lieu khi lugng dugc tdng hgp theo hang
dd ed tram Phan Thiflt va Phan Rang nam trung nam {bdng 2).
khu vgc nghien citu va nd phan inh khi diy dii

Bang 2. Lu>g^g mu'a, liro-ng boc ho'i tham chieu (Eto)
tinh chit khd ndng eiia khi hau nai diy.
trung binh nam cua 6 tram khi tiriyng

Bao
Nha
Trang
Phan
Rang
Phan
Thl6l
Tau
XuSn
LOC

cOdirliOu)

amkh&

\Z7

Nam iim

2195

2549

5262

1370

30

803

1266

2552

1590

28

449

638

1332

1868

1.

784

1142

1768

1758

26

<™)

931

1490

1970

1672

28

1652

2076

2597

1646

18

Khu vgc tram Bio Lgc li nai am udt nhat,
lugng mua hing nam d day rat cao (thudng trfln
20(JOmm/nam), nhiflu nam lugng mua tren
50U0mm/nam, Vdi lugng mua ddi dao nhu vay,
Hinh 3 Bdn ab nhl^l dQ Injng binh nhidu ndm khu Vi/c nghifin

dii\ la khu vgc phii hgp vdi nhiflu loai ciy ndng
nghiep khac nhau, Ngugc lgi, vdi lugng raua trung
3. Ket qui nghien curu
binh bang nim khi thip, chi khoing 800mm, Phan
3,L Bgc diim khi hgu ndng nghidp khu vifc NinhRang vi Phan Thiflt li hai trgm cd kieu khi hiu bin
kbd. Cd nhung n3m, lugng mua dudi 500mm/nam
Thugn vd Binh Thugn
di gay ra nhiing thiflt hgi ldn ve miia mang. Ngoii
Nhiflt dd, lu^ng mu'a v i boc thoat ho-i nudc:
viflc phal trifln hfl thdng thiiy lgi, d nhiing khu vgc
Ddi vdi nin ndng nghiflp chua phil tnen nhu d cd lugng mua thap nhu Phan Rang vi Phan Thiflt
Viflt Nam (hfl thfing thiiy lgi cdn yflu kem), thi miia cin chgn Iga nhung logi ciy chiu hgn tflt, thich urng
vg phy thugc cbii ylu vio lugng mua. Vi vgy, die vdi die diflm khi hgu nai day.
dilm diu tifln quan trgng cua khi h§u ndn§ nghiflp
Trgm Xuan Lgc vi Vung Tau cd lugng mua
cin xem xet dd li lugng mua. Cd thfl ndi ring mua
li dilu ki?n thiiy Igi tit nhat cho sin xuit ndng cao vi khi deu qua cic nkm, lugng mua nam khfl


vi nam am khdng chflnh nhau nhiflu, do dd ddi vdi
nen ndng nghiep Iua nude nhu nudc ta dac diflm
niy cd y nghia rat quan trgng. Nha Trang cung la
khu vuc cd Iugng mua Idn, nhung Iugng mua bing
nam d day khdng dflu, miic dd chflnh Iflch giua
nam khd vi nam am li rat cao, ngoai vin dfl thiflu
nudc do khd hgn, khi hgu thai tiflt Ihay ddi thit
thudng ciing tic dflng khdng nhd dfln sin xuit
nflng nghiflp.

Tir hinh 3 cbo thiy cd su chenh lech nhiet dfl

giiia eic khu vuc cua Ninh Thugn vi Bmh Thugn.
Dgc bd bifln, nhiflt do trung binh nhilu nim tren
26°C. Ddi vdi nhirng khu vgc cd lugng mua hang
nam thip cgng vdi nfln nhiflt dg cao se la dieu ki§n
tang cudng qua trinh bdc thoat hai nudc, dieu nay
khdng nhQng anh hudng trgc tiep dfln nang suit
ciy trdng ndng nghiflp, mi cdn tang cudng qua
trinh thoai hda dit do man hda, phen hda va sa
mgc bda.

Dfl bilu rd bon ve die diem khi hau ndng
nghiep cua bai tinh Ninh Thuan vi Binh Thugn,
chiing tdi su dung dQ lieu ciia 6 trgm khi tugng
xung quanh khu vuc nghien cuu vi du liflu tbu
dugc tir phin mflm NewClimLoe ciia FAO (diy Ii
du liflu trung binh da dugc FAO thu thip trong
nhilu nam), dfl thinh lap cac ban dd nhiet dd,
lugng mua, do bdc thoat hai nudc cho khu vuc
nghien cuu. Ban dfl dugc thanh lap bang each ngi
suy eac diflm gii trj tbeo phuang phap "ling gieng
gan nhat" {hinh 3-5).

Hinh 5 BSn dfi lu^ng boc - thoSt hcri nu'dc hang nam (Eto)

Khu vuc bd bien quanh tram Phan Thiflt va
Phan Rang cd khi hau bin khd. Kiflu khi hau nay
dac tnmg eho cac huyen trgng diem ludn khd hgn
li Bic Binh, Tuy Phong (Binh Thuin), Thuan
Nam, Ninh Hai (Ninh Thuin), Tuy nhien so vdi
tiflu chuin qudc tfl, khu vgc niy chua phai la noi

qua kbd bgn, van thich bgp eho viflc san xual nflng
nghiflp neu cd cac bifln phip canh tic hgp ly nhu:
chon diing thdi diflm bat diu mua vu, chgn loai cay
phu hgp cho timg loai dat.
Hinh 4 Ban 6b lu'png mira tmng binh hang nam

Ket qui tdng hgp cae bin dd tren cho thay khu
vgc nghifln ciiu cd the chia thinh bai viing cd
lugng mua ddi lip nhau. Lugng raua Idn d pbia tay
giam dan sang phia ddng theo dg ddc dia binh. Khu
vgc dgc bd bicn, dac biflt tip Irung d cic huyfln
Bac Binh va Tuy Phong (Binh Thuin); Thuan
Nam, Ninh Hii, Ninh San (Ninh Thugn) cd lugng
mua nhieu nim thap, cbi dgt khoang 600mm.
Nguyfln nhin chii yflu dan dfln hifln tugng niy la do
dieu kifln dia binh (khu vgc nay dugc bao quanh
bdi nhting diy nui cao), nhiflt dg dii ven bd khi
cao, khu vgc ngoii khai cd hogt dgng ciia nudc troi
la nhung yflu td gay cin trd mua [4].
368

Mua mu'a va chieu dai thdi gian km ydl:

Tir dQ li^u Iugng mua ngiy cua 6 trgm khi
tugng vi lugng bdc thoit hai tham chilu, chiing tfli
tifln hinh xic dinh chiflu dii thdi gian im udt hing
nam cho tirng tram khi tugng rieng biflt (hinh 6).
Mua mua dugc xac dinh khi lugng raua cao hon
1/2 lugng bdc thoit hai nudc, nhung thdi dilm phu
hgp dfl gieo trdng chi khi lugng mua cao hon

lugng bdc thoat hai nudc.
Lugng mua vi Iugng bflc thoit hai himg binh 10
ngiy dugc bilu diln tren cic do thj chieu dii im udt
trung btnh nhieu nim, cbo thay khi hiu d Ninh
Thugn vi Binh Thuan cd mgt mCia mua ro rgt. Thoi


gjan bit diu miia mua cd sg kiiic nhau giira cic
trgm, trong khi d6_ thdi diem kflt tbiic thdi gjan im
udt dudng nhu gidng nhau. Cd thfl nhgn thiy diflm
khic biflt ve thdi gian im udt giQa hai trgm Bao Lflc
(im udt nhit) vi Phan Rang (khd ban nhit):
- O tram Bao Lgc thdi gian im udt bit diu vio

cu6i thing 3 (de^d 9) vi kflt thiic vio cudi thing
11 (dekad 33), chiflu dil thudng trfln 200 ngay.
- O Phan Rang, Ihdi gian am udt bit diu mugn
thudng li tnmg tuin thing 9 (dekad 26) vi keo dii
din diu thing 12 (dekad 33), so ngay im udl ludn
il hon 100 ngay.

Hinh 6. Miia mira vd chi^u dii IhCrl gian i m vin


Mac dil cd su kbic biflt ve chiflu dai Ihdi gian
i m udt giua c i c trgm khi tugng (trir tram Phan
Thiflt), nhung cd the nhan t h i y ring lugng mua d
nhung khu vuc n i y rd ring cao ban so vdi lugng
bdc thoit boi nudc Iham chieu. Su kbic biflt d tram
Phan Thiet, mac dii chiflu dai thdi gian i m udl l i

khi dii (thudng tir dau thing 5 den cudi thing 11),
nhung lugng mua trung binh ebi tuong duong vdi
lugng bdc thoat hai nudc, dgc biet thdi gian mua d
day rat that thudng. Hau qua ctia van dfl nay la mac
dil lugng mua irung binh cd thfl dii dfl sin xuat
ndng nghiflp, nhung se tic ddng tiflu cue dfln nang
suit ciy trdng khi khdng cd mua trong vdng
20 ngay.
Tram Bao Ldc l i khu vuc am udt quanh nam,
thdi gian am udl keo dai tu 8 dfln 9 thing, thudng
bai dau vao cudi thing 3, dau thing 4, lugng mua
ting Iheo Ihdi gian v i Ihudng ldn nhit vio d i u
thing 8, lugng mua thudng xuyen cao bon ban so
lugng bdc thoat hai nudc, dieu kifln nay dac biflt

thuan Igi cho sin xuat ndng nghi?p. Trudng hgp
hai tram X u i n L^c va Vung Tau, day ciing la
nhimg khu vgc cd thai gian am udt keo dii. Nhung
do d i e d i l m dja hinh, ranh gidi khu vgc nghifln
ciiu dugc ngan cich bdi nhung day nui cao, do vgy
dac diflm khi h i u am udt ciia B i o Ldc v i Xuin Lgc
khdng anb hudng siu den vimg giihi v i dii ven
biln cua khu vgc nghien ciru. Tuy chi each hai
tram dd vdi khoang cich ngan nhung khi hgu cua
Phan Rang v i Phan Thiet lai mang d i e diem ban
khfl trai ngugc.
3.2. Bdnh gid ndng sudt cdy trong nong

nghifp

Tinh toan miic suy giim ning suit ciy trflng nflng
nghiflp ngan ngay bang each sir dgng du li^u khi
tugng ngiy cua 2 hgm khf tugng Phan Thilt v i Phan
Rang. Ket qua dugc thfl hi^n trong bdng 3. Thdng qua
kflt qui nay cd thfl dinh gia tinh trgng hifln tai vi xu
hudng cd the cd lien quan dfln van dfl lim giim san
lugng cay trdng ndng nghiflp do khd hgn.

Bang 3 Pham tram n a n g s u a ! cua cay t r o n g n o n g nghiep ngan ngay tai khu vg'c Phan Rang v i Phan Thiet
Tai tram Phan Thiei

Tgi Irgm Phan Rang
Chieu dai mua
Sm utH (ngay)

1981
1982

1994
1995
1996
1997
1999
2000
2001
2002
2003
2004
2005
2006

2007
Chu thich: dSu (-): thieu dO liflu

Chi4u ddi mua
i m IJM (ngay)


Tir bdng J cd the thiy d khu vuc tram Phan
Thiet xu hudng thay ddi ning suit cay trdng theo
hudng tich cgc. Dd li nang suit ciy trdng giai
doan nim 1994-2007 tang cao han giai doan nam
1980-1994 (tuy ring mirc tang len la khdng nhilu).
Dilu niy cd thi ly giai do lugng mua tir nam 1994
dfln 2007 ting len dang ke va tuong ddi ddng diu
qua eae nim (Idng lugng mua nhimg nam nay
Ihudng ldn hem lOOOnun) vi chilu dai thdi gian
im udt giai dogn nay ciing tang Ifln, cd Ihl ndi ring
lugng mua va chieu dai thdi gian am udt li hai yflu
to quan trgng trong sin xual ndng nghiflp.

Bien difln phin tram nang suit cay trdng ndng
nghiflp theo nim va chieu dai thdi gian im udl
(hinh 7) cho thiy nang suit dugc mfl phdng bang
md hinh Budget li tuong ddi dn dinh trong vdng
30 nam qua ddi vdi trgm Phan Thiflt. Dac biflt giai
dogn hi nam 1994 dfln nim 2007, ning suit ciy
trdng ndng nghiep dao dflng trong khoing 80% khi
trdng tren dit set vi khoing 60% khi trdng tren dit
cat. Nhu da phin tich d tren, xu hudng lich cgc niy
li do lic ddng ting len cua lugng mua vi thdt gian

am udt keo dai.

Phan Thift

Phan Rang

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1980

1995

1990

1995

.
3000

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70

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110

130

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170

190

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• Dat set D Dat cat
Hinh 7 B6 thj biSu diin phdn tiSm ndng suSt cdy trbng theo nSm vA chieu ddi Ihtri gian km irdi khu vi/c tr$m Phan Thi^t vS Phan Rang

Ngugc lgi, ddi vdi trgm Phan Rang, ning suat
Ihu dugc lir rad phdng bing md hinh Budget li
thip va khdng dn djnh h-ong ban 10 nam qua
(1993-2007), d§c biflt vdi logi dit eit. Dfli vdi ci
hai logi dil, nhilu nim ning suit ciy trong ndng
nghidp suy giim vl miic 0 do lugng raua khdng dii
cho sg phit trien ciia cay.
Tii hinh 7 cho thiy phin trkm ning suit tbu
dugc lir ciy trong trfln dit set cao hon bin so vdi

trdng tren dai cit. Die tinh giu nudc ciia dil set la
uu diflm tao nen sg khac biflt nay, tuy ring khi
ning thoit nudc ciia hai logi dit niy li tdt nhung
nudc sfl duge ti'eh irQ lau ban ddi vdi dit set. Mgt
chi liet Ihii vi cd thfl thay tii hinh 8, dd li ning suit
ciy trSng trfln dit set dn djnh ban khi trdng tren dat
cit; sin lugng cay trdng trfln logi dit nay sS It bj

inh hudng ban dudi tic dflng do sg thay ddi vfl khi
tugng (die biflt sg thay doi vfl lugng mua vi chieu
dii thdi gian am udt).


Tir dd thi biflu difln phin tram nang suit theo
chieu dii i m udt (hinh 7) chung ta cd thfl thay thdi
ky am udt (giai doan ma sd ngiy cd lugng mua ldn
hon lugng bdc thoit hoi nudc P>ETo) keo dii hon
100 ngay la diflu kifln can thiflt dfl dat dugc nang
suit bgp Iy. Thdi ky am udt ngan (cic nam 1982,
1998) tai trgm Phan Thiet va h i u bflt c i c nam tai
tram Phan Rang dflu cho nang suit thap l i nhimg
minh chirng cbo thay hau q u i khi m i chiflu dai sinh
trudng cua ciy trdng khdng phii hgp vdi chiflu dii
thai gian i m udt. Trong ragt sd trudng bgp, nang
suit vin cd the giam vdi giai doan ban ban thit
thudng v i cay trdng tren dit cat nhgy cam ban so
vdi cay trdng trfln dat set dudi tic dgng cua ban
bin v i hoang mac hda.
Lugng mua va chiflu dii thdi gian am udt l i bai
yflu td quan trong anb budng den ning suit cay
trdng nflng nghiep. Tuy nhien, trong mdt sd trudng
bap cdn cd nhung yeu id khac anh budng den nang
suat cay trflng. Chiing ta cd the quan sit thay su
anh hudng cua dieu kien han ban that thudng den
nang suat cay trdng d dd thi bieu dien phan tram

nang suat theo chiflu dai thdi gian am udt ciia trgm
Phan Thilt vao nam 1988 va 2007 (trfln dit set).

Day la nhQng n i m dflu cd thdi gian am udt keo dai
tren 100 ngiy v i tdng lugng mua hai nam niy li
tuang ddng, nhung lugng mua n i m 1988 khdng rii
dflu nfln phin trim n i n g suit cay trdng cd sg khac
biflt rd rflt (tuang img vdi cac nam 1988 v i 2007 Ii
25% va 87%).
N i m 1988, mua x i y ra nhiflu v i o giai doan diu
v i cudi cua thdi ky am udt, nhung mgt khoing thdi
gian d i i d giua ciia giai doan am udt (tir ngiy thir
48 dfln ngiy 130} lugng mua rit thip, ngugc lgi
vao nam 2007, la n i m ma cd cung mflt lugng mua,
nhung lgi dien ra k h i deu va tgp trung nhiflu vio
giai doan giua ciia thdi ky i m udt nen nang suit
cao han. Diflu do cd thfl thiy ring trong chu ky
sinh trudng ciia cay trdng ndng nghidp giai dogn
giua l i giai doan quan trgng nhat, cd tinh quyet
dinh den nang suit ciia c i miia vg. Vi vay, ddi vdi
khu vuc ban ban that thudng nhu Binh T h u ^ thi
chien luge phal trien thuy lgi mang y nghia sflng
cdn neu khdng mudn cd nhirng vg miia thit thu.

:

OOT

1 c=iMirs (mm) 1

1

16

31

46 61 76 91 106 121 136 '
Ngay-bat d^utLPl thangS

Elotrmi) 1

jtij

tii

61 76 91 106 121 136 151
Ngdy • bit d^u lir 1 thing 6

Hinh 8 Bieu dfi lu'png mua ngay tram Phan Thiet nSm 1988 v4 2007

Nhin chung, quanh kliu vuc trgm Phan Thilt
lugng raua Irong thdi ky ara udl la du cbo sin suit
dfli vdi nhung eay Irdng ndng nghiflp cd cbu ky
sinh trudng lii tren 100 ngay dfln 160 ngay. Nhung
do lugng raua d day khdng cao hon nhilu so vdi
lugng bdc thoat boi nudc, nen sfl l i kbd tranh khdi
nhung miia vg thit tbu nflu khdng xic dmh chinh
xic ngay bat dau miia vy. Han niia, day la khu vgc
cd difln tich dit cit cbiflm dien ticb khi ldn, Ii logi
dat cd khi nang tham v i thoat nudc rit nhanh, vi
vay can cd nhiing bifln phip thuy Igi bgp ly hd trg

372

ludi tieu hang ngiy neu mudn thu dugc ning suat
cao khi trdng ciy trfln logi d i t niy.
Ddi vdi tram Phan Rang, d i y la khu vgc khdng
phit hgp cho sin xuat ndng nghiflp ddi vdi c i hai
logi dit trfln khi khdng cd sg ho trg tii h? thong
thiiy lgi. Trong vdng ban 10 n i m qua sin lugng
ciy trdng ndng nghiflp d khu vgc nay thip v i
khdn^ dn dinh. D i e biflt khu vgc nay cd thdi k^- am
udl rit ngin (thudng it hon 100 ngiy), nfln nlu
khdng cd ljch trinh gieo trong hgp ly thi ning suit
ciy trdng se rit b i p benh.


4. Ket luan
(i) Dac diflm khi hgu ndng nghiflp khu vuc Nam
Trung Bg (Ninh Thuin va Binh Thuin).
Ninh Thugn vi Binh Thuin cd hai kilu khi hiu
tuong phin: am udt d phia tiy vi ban khd d pbia
ddng. Lugng mua hing nam d phia liy ludn Iren
2000mm, trai ngugc d phia ddng thudng il hon
1000mm. Tuy mang hai kilu khi biu khac nhau
nhung Ninh Thuan va Binh thugn chi cd mdt miia
mua rd ret vi lugng mua thudng tap trung vao giQa
miia mua (khoing thing 9 vi 10).
Chiflu dii thdi gian am udt la yflu td quan trgng
trong sin xual ndng nghiflp, dgc biet quan trgng
hon ddi vdi nhQng khu vgc khd ban (nhu cic
huyfln Bic Binh va Tuy Phong ciia Binh Thuin;
Thugn Nam vi Ninh Hai ciia Ninh Thugn). Ddi vdi

cay trdng ndng nghiep, chieu dai thai gian im udt
Uen 100 ngiy la yeu cau cin thilt.
(ii) Danh gia miic suy giim ning suit cay trflng
nflng nghiflp ngan ngiy
Dfli vdi nhQng khu vgc khd hgn bay bin khd,
ciy ndnp nghiep dugc trdng Iren dit set ludn cd
ning suit cao ban nhiflu so vdi eay trdng tren dil
cat. Die biflt ddi vdi nhQng viing cd lugng mua
ludn thit Ihudng nhu Phan Thilt thi nang suit cay
ndng nghiflp dugc trdng tren dit set tuong ddi
fln djnh.

dau gieo trdng thich hgp cho khu vgc tinh Binh
Thugn thudng vio diu thing 5 hang nam vi diu
thing 9 cho tinh Ninh Thuin.
Ddi vdi khu vuc Phan Rang, noi cd lugng mua
thap vi chiflu dai thdi gian im ngan, ciy trdng
nong nghiep chi cd the dat nang suit cao khi ed sg
hd trg tir he thdng thiiy lgi, ddng thdi xac dinh
dung tbdi diflm gieo trdng.
Xiy dgng cac hd du tru nudc li cdng viee quan
trpng dfl giam thieu nhQng rui ro thoai bda dat do
hoang mac bda vi xim nhap man, dac biet li viec
nit ngan thdi ky im udt do tic ddng ciia bifln ddi
khi hau.
TAILIEUDAN
[I] Dirk Raes. 2002: BUDGET A soil water
and salt balance model.
[2] Jensen. M. E, 1968: Water consumption by
agricultural plants. Chap 1 in Water Deficits and

Plant Growth. Vol II, Academic Press, New York,
pp. 1-22).
[3] Kipkorir, E.C. and D. Raes, 2002:
Transformation of yield response factor into
Jensen's sensitivity index. Irrigation and Drainage
Sytems 16. KJuwcr Academic Publishers. Printed in
Ihc Netherlands (Tr 47-52).

Viflc xic djnh diing thdi diflm bit diu miia vg
[4] Phgm Quang Vinh, 2012: Dinh gii tie dflng
CO ^ quyet djnb doi vdi ci raiia vg, Tbdi diera bit cua bifln ddi khi hgu loin ciu vi hoang mac hda
dau miia mua duge xae djnh la khi ma lugng mua dfln mdi trudng vi xi hgi d khu vgc Nam Trung
cao ban lugng bdc thoit hai nudc. Thdi diem bit Bfl. Dfl til Nghj djnb tbu Viflt - Bi, 2010 - 2011.

Assessing the impacts of agro - climatic conditions on annual trees in Ninh Thuan and Binh Thuan province
In this article, the authors used Budget model to process ths daily meleorological data of two meteorological stations
Phan Thiol and Phan Rang (and refer 4 meteorological stations near Ihe case study) in 30 years lo calculate water
balance in soil to assess the drought current for some annual trees in Nmh Thuan and Bmh Thuan province, the driest
region of Vielnam. to give the results of decreasing percentage productivity {%). By that way, the authors estimated the
trend reducing agncultural crop yields due to drought. In the tact, insufFicienl amount of water would indicate the nsks of
deseriification as well as filtering salt phenomenon in the region, the mam direct reasons impact on agricultural
productivity. The calculations were performed for two contrasting, sensitizing with drought and quite popular soil types in
this area is that clay soil and arenosol. The results will be the believable scientific fundamentals for manager and farmer
having solutions mitigating vulnerability by drought for agricultural tree, througti planning crop calendar, agricultural trees
adapting lo drought, desertification and climate change.