GM fKIIu mi qua De tai - Dy an
THUC TRANG d NHltlVi Mdi TRUdNG OAT NdNG NGHIEP VUNG CHUYtN CANH RAU, HOA
T I N HLAM OONG
VAOE XUAT CAC GIAI PHAP
X O L YN G U Y I N B I C H T H U , LE M I N H CHAU, LE HU'U QUANG, NGHIEP QUOC VLTONG
Trung tam nghien eCfu dat, phan bon va mdi tnfdng phia Nam
N
ghe trdng rau, hoa da cd tu lau ddi d Lam Ddng nhd dieu kien ttr nhien thuan lgi vdi hau het cac chung loai rau, hoa dn ddi phuc vu ngi tieu va xuat khau. CarM tac lau dai vdi viec dau tix phan bdn, thudc bao ve thuc vat (BVTV) cao d day la rMiing tac rMan cd kha ndng gay d rMiem mdi tradng dat va ngudn nudc mat, nudc ngam,... Vi vay rat can thiet nghien ciiu darM gia de cd ca sd khoa hgc cho dirM hudng carM tac rau, hoa cd nang suat, chat lugng cao iMung khdng gay drM hudng xau tdi chat lugng dat va cac thdrM phan mdi trudng khac.Trang tam nghien ciiu dat, phan bdn va mdi tradng phia Nam da tien harM ngMen Cliu darM gid hien trang d rMiem mdi tradng dat ndng nghiep (vung chuyen canh rau, hoa thugc Da Lat - Lac Duong, Dan Duong - Diic Trgng) de lam co sd cho viec de xuat cdc bien phap phdng trarM va khac phuc d rMiem cd hieu qua mdi trudng dat chuyen catM rau, hoa ciia tirM Lam Ddng.
Qua cac dgt khao sat, dieu tra ndng hg va khoarM vung lay mdu trong vung nghien ciiu, rMdm nghien ciiu da tien harM phan tich mau dat, mau nudc gdm cac chi tieu: pH hiru ca, N tdng sd, Photpho tdng sd va de tieu. Kali tdng sd va de tieu, Na tdng sd va trao ddi, Ca, Mg trao ddi, sat va nhdm trao ddi; Kim loai nang: Cr, Cd, Cu, Zn, Pb, Hg va As; Nhdm hgp chat tdn du ndng dugc: Chlorphos, Methamidophos, Methyl Parathion, Trichlofon; Vi sinh vat gay hai: Coliform, E. CoU.
Kit qua xu ly sd lieu dieu tra, sd lieu nghien Cliu thuc dia vd phan tich de phat hien van dl lien quan din chit lugng mdi tradng dit khu vuc nghien ciiu.
1. Tinh chat Iy hoa dat khu vuc nghien cuu
Dit d khu vuc nghien ciiu tap trang tren 2 rMdm dit chirM la dat dd vang va dat phu sa sdng sudi, trong do chii yeu la rMdm dat dd vdng. Dit cd thdrM phan co gidi trang birM din nang, chua, pHj^^o thudng chi khoang 4,8-4,9. Dung tich hap thu va do no baza deu d miic thap, chi dat 10,5-13,5 me/100 g dat va 30-35%. Trong cac ylu td dirM duang cho cay trdng thudng cd hiiu ca, kali kha, ngoai ra, dam tdng sd vd lan, ka li de tieu thap.
2. v l tap quan canh tac rau co anh hudng toi chat luong moi trudng
Thdi gian carM tac lau nam (it rMat la 10 nam) vd lien tuc khoang 3 vu/nam, giua cac vu chi de cho dat nghi khoang 10-15 ngdy.
Lam dat: tap quan thay dat mat hoac bd sung them dat mdi cao tren ddi xudng vai ba nam mot lan. Viec xu ly dat bang hda chat ciing rat phd bien. Hda chat de xu ly chu yeu la Mocap, Nebijin (dung cho rMiing vudn trdng cai bap) va vdi. Lugng vdi su dung rMieu, trang binh cho 1.000 m^ la 160 kg.
Sw dung phdn bon
Phan hiiu ca dugc su dung rMieu ca ve so lugng va chiing loM.
Phan ca van cdn dugc dung (11-20% sd hg dieu tra vdi lugng su dung birM quan tii 4,5- 6,5 tan/ha/vu) trong khi da cd rMieu khuyen cao khdng nen su dung loM phan nay tu nhieu nam qua. Ngoai ra cdn sii dung cac loai phan hiiu CO khac nhu phan chudng, phan de, cac loai phan hiiu ca che bien vdi lugng bdn cao (tmng binh 15-20 tin/ha/vu).
Ijioi thieu ket qua tie tai - Dy an
Phan khoang cung dugc sii dung rit nhilu han tu 30 din 45%, cd biet tdi ban 60% ddi (Bang). Lugng sii dung kha cao so vdi miic vdi ca N, P, K. Ngoai phan bdn gdc, phan bdn khuyin cao tren ca 3 ddi tugng rau (an la, an la vdi rat rMilu chung loai ciing dugc phun qua, an cu) va hoa. Miic su dung thudng cao xit bo sung tu 3-5 ngay mot lin suot vu.
Bang ket qua dieu tra miTG do sir dung phan khoang cho rau
STT Nhom cay trong
Lu'O'ng phan bon thirc te qua khao sat 1
2 3 4
Rau an la Rau an cu Rau an qua Hoa cac loai Khuyen cao
1 2 3
Rau an la Rau an cu Rau an qua
Ham lu'O'ng N-P-K (kg nguyen chat/1.000 m^) N
38,3 44,6 54,4 62,3 N 25,00 15,00 20,00
P O 28,5 36,3 58,4 70,4 P,0.
15,00 18,00 12,00
K,0 27,2 45,5 52,6 55,3 K,0 20,00 20,00 15,00
Nguon: So lieu diiu tra hien trang khu VLTC vung nghien cuv
Thuoc BVTV
Cac thudc BVTV ndng dan su dung diu nam trong darM muc cac loai thudc dugc phep cua Bg Ndng nghiep va PTNT. Da so ndng dan su dung cdc loai thudc BVTV theo kirM nghiem, theo chiing loai cay trdng va dac biet la theo dien bien ciia thdi tiet. Lieu lugng sii dung thudng cao ban nhieu so vdi miic khuyen cao.
3. Ket qua nghien cuu chat lugng moi truong dat
a. Dp chua ddt
Tren 70% sd mau dat khu vuc canh tac rau, hoa cd pH > pH dat ddi chiing va cd xu hudng kiem (ldn ban 6,5). Hien Mgng nay phd bien d tat ca cac khu vuc nghien ciiu, nhung ro rMit la d Lac Duang (tren 92%) sd mlu nghien ciiu). Trong khi do theo dac dilm phat sirM hgc, dat d day hau hit chua, pH tu 4-5,5.
Ndng dan thudng su dung vdi bdn lot vai Heu lugng rit ldn, phd biin tu 1-1,6 tin/ha/
vu. Vdi dugc dung theo quan niem ciia hg la de sat trung dat. Tac dgng lau dai cua tap quan nay the hien rat ro d viec lam thay ddi phan ling ciia mdi tradng dat tu it chua sang kiem. Thay ddi nay se keo theo hang loat bien dgng khac den tinh chit hda hgc dit.
b. Chdt him ca dot
Ham lugng chat hiiu ca (OM) trong dat khu vuc nghien ciiu dao dgng tu \,1A-1,12
%). CJ dat chuyen carM rau, hoa, chat him ca dat thay ddi rat rMilu so vdi dac tiiM dat ddi chiing theo hai hudng ngugc rMau: hoac la tang len rat rMieu, hoac la giam marM My tung khu vuc phu thugc vao chung loai cay trdng va lugng phan bdn su dung, nhung xu the chii yeu la tang cao so vdi dit ddi chiing.
Dung phan hiiu co vdi lugng ldn doi vdi canh tac rau, hoa la dieu tat ylu. Phan him ca rMieu chung loM dugc su dung vdi miic bdn trung birM tu 10-15 tin/ha/vu, rMilu hg bdn tdi 20-25 tan/ha/vu da day ham lugng hiiu ca trong dat len. 100%) mau nghien ciiu khu vuc Da Lat deu co ham lugng hiiu ca cao ban dat ddi chiing, tuemg iing vdi lugng phan hiiu ca dugc bdn cao.
c. Cdc chat dinh dw&ng da Iwffng vd cation trao doi
Theo dac diem phat sirM hgc dat, cac loai dat deu cd ham lugng N trang birM, lan va kali dl tieu thap. Khi nghien ciiu cac mau dit trdng rau, hoa rMieu narn d day, sd lieu phan tich ban 200 mau cho thay ham lugng lan va kali dl tieu cao ban rat rMieu lan so vdi dit ddi chiing.
i n i i i ^ i i i ir^t;?!. \w
Gioi thieu ket qliaDe tai - Du an
Ham lugng lan vd kali dl tieu deu cao, phd biin tu 17 din tren 200 mg/100 g dit ddi vdi lan; tu 17 din tren 120 mg/100 g dit doi vdi kaU. Cao han tu 10 din 20 lin, ca biet cao hem cd tram lan (ham lugng P) so vdi mau ddi chimg. Nguyen nhan chu yeu la do lugng bdn qua cao va du thua nhu da trinh bay, vua lang phi phan bdn do cay khdng sii dung het, vua tang khd ndng gay d nhiem dat trdng va ngudn nudc. Lan la nguyen td rat de bi nia trdi khdi dat khi bdn du thua va ldm phii dudng hda ngudn nudc mat rat rMarM chdng. Dieu nay the hien rd khi nghien ciiu mdt he thdng mau dat theo dia hirM ddi hi dinh xudng sudn vd tdi thung liMg. Dat trdng rau, hoa d thung limg thudng cd hdm lugng lan de tieu cao nhat, tu 130-240 mg/100 g dat so vdi cung loai dat rMung d vi tri sudn hoac dirM ddi (chi trong khoang tu 20-70 mg/100 g dat). Khu vuc thung liMg d Dem Duemg ciing Id nai dat canh tdc cd ham lugng lan va kali de tieu cao nhat d Lam Ddng.
Rd rang la, viec bdn phan khodng qua cao dang la nguy ca true tiep gay d nhiem dat vd ngudn nudc. Ket qua dieu tra ndng hd ciing cho thay ndng dan chu yeu bdn theo cam tinh, rMat la phan lan. Bdn lot mdt lugng ldn phan lan Id tap quan khdng the bd cua ngudi dan d day, chua ke bdn thiic rMieu lan vdi sd lugng ldn cac loai phan N, P, K khac.
Trong sd cdc cation trao ddi dugc nghien Cliu, cd bat thudng nhieu rMat Id Na trao ddi.
Khu vuc Dd Lat su dung nhieu phan cd nen Na trao ddi tich liiy cao trong phiic he hap phu dat. Day ciMg Id mdt trong rMimg nguyen nhan gay thoai hda tinh chat vat ly dat, phd buy cau tnic dodn lap lam dat bi chai cimg, la mdt trong nhimg nguyen nhan cua tap quan thay dat mat vdi ba nam mdt lan d day.
d. Kim loai nang vd As
Ket qud nghien ciiu khdng phdt hien Hg trong tat cd cdc mau dat vd nudc tudi.
Ham lugng Cr, Zn, Pb deu nam trong miic an todn, chi cd 4 mau cd Pb vd 4 mau cd Cr cao ban tieu chuan cho phep rMung khdng dien hirM.
Khdng phdt Men hdm lugng Cd trong dit
khu vuc Da Lat - Lac Duemg rMung Cd trong mlu d Dem Duemg - Diic Trgng vugt tieu chuan cho phep kha nhieu. Cd cd the cd ngudn gdc tu phan lan rMung do kha nang hda tan ciia nguyen td Cd cao nen khdng phat hien trong dat do da bi nia trdi vao ngudn nudc. Trong nudc Mdi cd 52/59 mau chiia Cd cao hem 0,1 mg/1 ciing chiing td dieu ndy. Tuy nhien cd the do lugng bdn qua cao vd dia hirM it ddc hem khu vuc Da Lat - Lac Duemg nen phat hien dugc Cd trong dat d Dem Duang - Diic Trgng.
Hau het mau nudc tudi d Dem Duemg - Diic Trgng deu cd Pb vugt 0,1 mg/1 mac du khdng phat hien trong dat. Theo nhieu nghien Cliu, khd ndng tich liiy Pb trong rau cd tuemg quan chat vdi Pb trong dat hem la vdi Pb trong nudc tudi.
Rieng nguyen td Asen dugc phat hien cd hdm lugng cao vugt tieu chuan cho phep ddi vdi dat ndng nghiep khd phd bien trong sd mau dat nghien ciiu, (chiem 65% sd mau) d Da Lat - Lac Duemg. Ham lugng As cao gap nhieu lan tieu chuan cho phep, phd bien tu 2,5 den 4,5 lan, tham chi cd rMieu mau cao hem tdi 75 lan. Hdm lugng cao rMat phdt hien dugc la d thi tran Lac Duong (111 mg/kg) tren dat ddi, chua canh tac. Khu vuc Dem Duemg - Diic Trgng (chu yeu la dat phu sa va thung Mng) cd ham lugng As trong dat rat thap hoac khdng phat hien. As trong tat ca cdc mau nudc tudi deu khdng dang ke hoac khdng phat hien.
Dieu dac biet Id As phan bd cao chii yeu d khu vuc dat ddi, dat phdt trien tren dd set. Ciing cd nhieu nghien ciiu cho thay da me hinh thdnh dat la ngudn gdc cua As trong dat, rMit la dd tram tich cd chiia arsenal (AsO^^) trong thanh phan khodng vat.
Mdt sd nghien ciiu budc dau ve Asen trong dat, nudc Mdi vd cay rau d Dd Lat - Lac Duang va Dem Duang - Diic Trgng ciing cho ket qua khdng ddng deu giiia cdc khu vuc do sd mau cdn qua it. Ngudn gdc cua Asen trong mdi tradng dat, khd nang tich liiy trong cay (cu the la rau), rMiing yeu td tac dgng tdi su chuyen dich Asen trong dat va cay trdng,...
Id rMimg van de can nghien ciiu mdt each he thdng. Chi cd tren ca sd lam rd rMimg vin dl tren mdi cd the de xuat nhimg giai phap han
Gioi thieu ket qua De tai - Du an
che nii ro do d nhiem Asen cho dat trdng va day chuyen thuc pham.
e. Hffp chdt hiru cff kho phdn huy sinh hgc (ton dw ndng dwffc)
Tat cd cac mau dat va nudc phan tich deu khdng phat hien tdn du hda chat BVTV. Tuy rMien, ket qua dieu tra cho thay lugng thudc BVTV dugc su dung qua nhieu so vdi khuyen cao. Cach sii dung chu yeu theo kirM nghiem, it theo hudng dan cua nha san xuat. Do thdi gian phan buy trong dat ngan nen khdng phat Men dugc tdn du trong dat rMung chac chan la cd anh hudng tdi chat lugng ndng san.
/ Vi sinh vdt co khd ndng gdy benh Khdng phdt hien E.Coli la vi khuan gay benh trong mau dat nghien ciiu vd nudc Mdi...
Ket luan
1. Tap qudn canh tac cua ngudi dan khu vuc chuyen carM rau, hoa d Lam Ddng cd nhieu van de tac ddng tdi chat lugng mdi tradng dat iMu bdn vdi, bdn phan khoang vdi lieu lugng cao gap rMieu lan (thudng tix 30 den 45%), so vdi miic khuyen cao cua ngdnh ndng nghiep).
Cd 17-20%) sd hd cdn sit dung phan cd khdng rd ngudn gdc. Cac thudc BVTV ma ndng dan su dung deu nam trong darM muc dugc phep su dung ciia Bd Ndng nghiep va PTNT, tuy nhien lieu lugng thudc BVTV dugc su dung cao hem rMieu lan so vdi khuyen cao.
2. Do thdi gian canh tdc lau cung vdi tap qudn canh tdc cua ngudi dan lam cho mdi trudng dat khu vuc chuyen canh rau, hoa tinh Lam Ddng xuat hien mdt sd van de lien quan tdi bien ddi tirM chat dat can dugc luu y va khac phuc, gdm:
+ Tang tri sd pH dat tix 0,5 tdi tren 2,5 don vi.
+ Ham lugng chat dirM dudng de tieu P^O^
va K^O tang cao bat thudng hang chuc lin so vdi dac tinh phat sirM hgc cua dit.
+ Ham lugng Na trao ddi tang cao d dit su dung phan ca lam thay ddi ciu tnic dit, dit khd thoat nudc dan tdi tap quan thay dit trong rau sau vai nam canh tac.
+ Ham lugng Cd trong dat khu vuc Dan
Duang-Diie Trgng vugt tieu chuin cho phep, iMieu khd ndng lien quan tdi viec su dung phan lan lilu lugng cao.
3. Chua phdt Men d rMilm kim loai ndng trong dit ddi vdi Cu, Cr, Hg, Pb, Zn, Mn.
Rieng As cd tich My eao trong mdi trudng dit nhung khdng phat Men trong nudc tudi. Nhilu kha nang ham lugng As eao trong mdi tradng dat cd ngudn gdc tu mlu chat hirM thdrM dat nhung can dugc nghien ciiu mdt each he thdng de cd ket Man chirM xac.
4. Chua phdt hien van de d rMiem dat bdi vi sirM vat gay berM va hgp chat hiiu ca khd phan hiiy sinh hgc. •
TAI LIEU THAM K H A O
Nguyin Van Bp, Bui Huy Hien, 2003, Bon ptian can doi cho cay trdng a Viet Nam, tCr ly luan den tiiirc tiin, NXB Nong nghiep - Ha Npi.
Vu Cao Tliai, NguySn Bfch Tliu va ctv, 1996, Nghien CLfU anh hu^ng cua nutfc thai cong nghiep tol moi truv/ng dit ndng nghiep khu cong nghiep Phuvyc Long - Thu Dire, Tp. HCM, Bao cao khoa hpc Trung tam Nghien CLPU va chuyen giao Ky thuat Dat Phan.
Bui Cach Tuyen, 3/2001, Anh hwang cua hoa chat nong nghiep len nong san, moi truing va sCrc khoe con ngwai, Tham luan trinh bay tai hpi thao phap che phan bon Viet Nam - Tp. HCM.
Nguyin Bich Thu va ctv, 2005, lfng dung bai toan dir bao kha nang tich luy va lan truyin kim loai nang trong moi trwdng dit KCN Nhan Trach - Ddng Nai, Ket qua nghien cifu l<hoa hpc Vien TNNH, quyen 4 NXB Nong nghiep.
Bao cao khoa hpc, 7998, Diiu tra hien trang 6 nhiim moi truxfng dit va nghien cuu san xuit thir nghiem rau sach tai vung rau Da Lat - Trung tam NC Cay thyc pham Da Lat.
R.N.Yong,A.M.O.Mohamedand B.P.Warkentin. 1996, Principle of Contaminant Transport In Soils. Heavy metals in transfer in the system air-soils-plants. R. Impens, E. Delcarte and T Piret. Scope Belgium- Proceedings
"Metal cycling in the environment", Brussels.
A study of soil pollution by metals in Reunion - Environmental Risks of Recycling Research Unit website 08 February 2006 - CIRAD)
Intervention values and target values - Soil quality standards (Ministry of Housing, Spatial Planning and Environment, Dept. Soil Protection. The Netherlands, 2004).
