TRNG I HC LT KHOA NNG LM

BI GING TM TT (Dnh cho sinh vin ngnh Nng hc v Cng ngh sau thu hoch)

HC PHN

K THUT NH KNH

Ngi bin son:PHM NGC TUN

THNG 06/2008

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MC LCBI 1 PHN LOI NH CHE PH ............................................................................ 3 1.1. Cu trc nh knh:.................................................................................................... 3 1.2. Cu trc nh c mi che:.......................................................................................... 8 Bi 2: ............................................................................................................................ 10 XY DNG NH CHE PH ..................................................................................... 10 2.1. V tr nh knh v nh mi che:.............................................................................. 10 2.2. Lp t b khung nh knh cng nh cc loi nh che ph khc: ......................... 14 2.3. Cc dng mi lp: .................................................................................................. 23 2.4. Cc dng lung, mng, chu trng cy s dng trong nh knh:........................... 29 2.5. Cc loi gi th trng cy trong nh knh: ............................................................. 34 2.5.1 Yu cu chung ca gi th trng......................................................................... 34 3.5.2 Thnh phn ca gi th: ....................................................................................... 35 2.6. Cc h thng iu khin thng dng trong nh knh:.......................................... 45 Bi 3:............................................................................................................................. 46 MI TRNG NH CHE PH ................................................................................. 46 3.1. Cc yu t mi trng trong nh che ph: ............................................................ 46 3.2. Cc h thng iu khin v cch iu khin mi trng trong nh che ph:........ 47 3.2.5 H thng ti: ..................................................................................................... 54 Bi 4 .............................................................................................................................. 56 BO DNG NH CHE PH................................................................................... 56 4.1. S cn thit ca vic bo dng nh che ph:....................................................... 56 4.2. Cc nguyn nhn gy h hng nh knh:............................................................... 56 4.3. Cc bin php khc phc v bo dng nh knh nh che ph: ......................... 56 Thut ng chuyn mn ................................................................................................. 58 TI LIU THAM KHO ............................................................................................ 59

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BI 1 PHN LOI NH CHE PH1.1. Cu trc nh knh: Cu trc nh che ph l tng th cc b phn cu thnh nh che ph. V cu trc c bn ca mt nh che ph gm 4 phn: - Phn nn mng: y l b phn lin kt gia nh che ph vi mt t. B phn ny thng c lm bng cc loi vt liu khc nhau nh: gch, b tng. Phn nn mng c th xy ton b ng vin xung quanh nh, xy cch khong, hoc cng c th ch xy nn mng gi cho cc tr chnh ca khu nh. - Sn nh, mt sn: c lm bng cc vt liu khc nhau. Thng thng, i vi nh che ph hoa, vt liu sn nh thng lm bng t, ct y cng chnh l vt liu ch yu ca gi th, lung trng. Trong nh che ph trng hoa, cc li i c th lm bng b tng hoc gch lt ng. Tuy nhin, yu cu ca vt liu sn nh l kh nng thot nc. Nh vy, xt v kh nng ny, nu vt liu lt sn l b tng th yu cu phi xem xt n h thng tiu nc. i vi nn t th kh nng tiu nc thng tt hn b tng. Sn nh thng c xy theo hng nging v mt pha m bo kh nng tiu nc trong nh che ph. Sn nh c th xy ton b nh che ph hoc c th chia theo , theo cc li i xung quanh cc lung trng. - Phn mi che: lm bng cc vt liu trong (knh, mng nha trong, knh nha,...) cho php nh sng xuyn qua. - Phn sn nh: l b khung chnh ca nh che ph, c th lm bng cc vt liu khc nhau nh: st, cc loi hp kim, khung nhm, v cng c th lm bng g, tre, .. Phn khung sn nh c th c to thnh bi cc vt liu hnh ng c ni vi nhau. di cng nh din tch nh che ph c lp t theo thit k vi cc hnh dng khc nhau nh: vung, hnh ch nht, hnh a gic,... Mi mt khung nh che ph theo thit k u ni n cc ch tiu sau: chiu di nh che ph, chiu rng nh che ph, chiu cao mng nc, s nhp, bc nhp, chiu di nh tnh theo nhp, chiu rng nh tnh theo mng nc, din tch phn hnh lang, din tch phn ng nh che ph, tng din tch nh che ph, chiu di ca ra vo, s lng, cu trc v ln cc ca thng gi,.. Phn ny gm c cc chi tit theo sau: Ridge: l nh nc ca nh che ph. Vertilator: l thng gi l nhng b phn c th di chuyn c ca nh che ph cho l nhng b phn c th di chuyn c ca nh che ph cho php lu thng gi mt cch t nhin. Chng c th c lp mt bn vch, trn mi hoc c th lp trc tip trn nh (nc nh). Eaves: mi hin Purlin: (n tay) l b phn lp trn mi, dc theo chiu di ca nh knh v mi u purlin c lp bulong gn vi mi khung gin ko. Sill: ngng ca Chords: giy cn3

Strut: thanh chng Rafter: rui Sidewall: vch bn Sidepost (Anchor support posts): tr bn, l cu trc chng ch yu ca nh knh,tr bn c xy cn i dc theo nh knh v c xy pha trn chn b tng. Curtain wall: vch chn Ground level: mt t Footer: chn (mng)

Hnh 1.1 Tng th ca mt nh mi che Plastic ni tip hin i.

Hnh 1.2: S cu trc b khung mt bn ca mt Nh knh.

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Hnh 1.3: Cu trc ca mt nh knh n gin C 3 loi cu trc chnh ca nh knh: 1.1.1. Nh knh c mt vch dnh lin vi mt cng trnh khc (attached greenhouse): y l kiu nh knh n gin nht. Mt s kiu thuc loi nh knh ny c s dng sn xut cy trng mang tnh thng mi v ng thi cng c th c s dng trng by cy trng trong cc quy hng bn l, cho cc khu vn trung tm, vn phng lm vic, v c th trng by trong nh. im thun li ch yu ca loi nh knh ny l gim c chi ph xy dng, v qu trnh xy dng tng i n gin. Tuy nhin, do chng c xy dng p st vi cng trnh, c th b cng trnh che chn trong hng chiu sng, nn thng thiu nh sng. ng thi cng rt kh iu khin s thng thong v nhit nh trng. C ba kiu nh c bn thuc loi ny: Nh knh p tng: Kiu ny c xy dng da vo mt cng trnh hin ti. nh ca mi nh knh c gn mt bn ca cng trnh v mi nghing ra xa khi cng trnh. hn ch mc che bng ca khu cng trnh th loi nh knh ny nn c xy dng theo hng Nam ca cng trnh.

Hnh 1.4: Nh che ph kiu p tng

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Nh knh hai mi p tng - Kiu nh ny gm 2 mi vi nhng thanh rui c chiu di bng nhau v bc tng cui cng c p st vi mt cng trnh. Loi nh knh kiu ny c ng dng ph bin hn loi p vch. Bi v chng c th thy c nhiu ni v ni chung, chi ph xy dng v chi ph si m cho nh trng cao hn loi p vch. Nh knh nh di ng c thit sn y l loi nh knh c lm sn, c th tm c nhng nh knh kiu ny vi nhng mu kch thc ph hp vi nhng khung ca s c kch thc chun. Kiu nh loi ny thng c kch thc nh, ch s dng trng by hoa cc gia nh, khng ph hp vi kinh doanh mang tnh cht qui m. ng thi loi ny rt kh iu khin cc iu kin nui trng. 1.1.2. Nh knh c lp: Nhng nh knh sn xut qui m thng mi thng l nhng cu trc c lp c hai mi. y l loi nh knh c cu trc phc tp hn c cn i khng gian c tn dng tt cho nhng li i thun tin v nhng dy nhn ging. V c nhiu u im hn, loi ny c th iu khin c yu t ngoi cnh nh nh sng, nhit , thng thong. Nh cc loi nh knh hnh ch A (ph bin nht) c dng nh knh c mi khng i xng thng thch hp cho cc vng xy dng nhng khu vc c a hnh i dc. C loi nh knh c mi hnh vm chp (quoset) hoc hnh chp. Loi nh knh c lp c nhiu u im nh: - Mi trng d iu khin - Vic thng thong gi d dng hn - Vic tu b, bo tr d dng hn so vi loi nh knh c vch ta. Tm li c 8 loi nh knh: 1. Even-span: nh c mi i xng ch A 2. Uneven-span: loi nh c mi khng i xng 3. Lean-to: loi nh knh ta vch 4. Quonset: dng vm chp 5. Gothic arch: dng chp 6. Curvilinear: dng hnh cong 7. Curved eave: dng hnh cong c mi hin. 8. Dome: dng vm

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Hnh 1.5: Nh che ph kiu mi i xng ch A:

Hnh 1.6: Nh che ph kiu vm 1.1.3. Nh knh lin tc (connected greenhouse). L loi nh knh ph bin hn c, mt s cc phn nh knh n thng c gn st bn nhau, gim c chi ph lp knh bn trong cc bc tng k bn. S sp xp cc lung trong nh knh thng khc nhau. Mt s s lp t cho nhn ging vn hnh tt khng gn cc bng mt cch c nh, s sp t chng khc nhau ty theo loi trang thit b nh cc xe nng, xe b in ... c dng mang nhng ngn t v cy trong v ngoi nh nhn ging. Loi nh knh ny phc v cho hnh thc sn xut trn qui m rng ln v chuyn nghip. Gia cc nh knh c gn vi nhau bng cc mng xi (gutter). Mi nh knh c cu trc ch A, cu trc mt mi nghing, hoc cu trc vm v c xy dng ni lin nhau.

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Hnh 1.7: Nh che ph ni tip 1.2. Cu trc nh c mi che: Thc cht cu trc nh c mi che cng nh cu trc nh knh. Tuy nhin, n gin hn cu trc nh knh. V c bn th cu trc nh c mi che cng gm 4 phn: nn mng, sn nh, khung sn v phn mi che. Nhng vt liu lm mi khng phi l knh, m s dng cc loi vt liu trong khc nh polyethylene, v mt s loi cht liu nylon tng hp khc,... y l nhng vt liu tng i r tin, chi ph xy dng thp hn so vi cc loi nh che ph bng knh, do loi nh che ph v cc cc nh che ph ci tin c s dng rng ri qui m nh h gia nh.

Hnh 1.8: Dng nh knh c lp, dng hnh bn cu.

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Hnh 1.9: Dng nh knh ta vch.

Hnh 1.10: Dng nh knh ch A ni nip.

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Bi 2: XY DNG NH CHE PH2.1. V tr nh knh v nh mi che: Sau khi nghin cu mt cch t m v kiu dng ca cc loi nh knh, chng ta phi xc nh v tr lp t nh knh. Nhng nhn t cn quan tm khi kim tra xc nh v tr xy dng nh knh. N bao gm: 2.1.1 t ai v kh hu: Xem xt cn thn t ai v kh hu l mt yu t rt quan trng trong vic chn v tr nh knh thng mi nu mun n tn ti mt cch tit kim v phng din cnh tranh vi cc nc thch hp hn. Mt ngi lm vn khng chuyn nghip trong nh knh mc d anh ta c th khng chn nhng vn lm vic t nht bit c cc nguyn tc ca kh hu v tm quuan trng ca n. iu kin kh hu l mt yu t rt quan trng trong vic chn la v tr xy dng nh knh. Do bc ny phi ht sc cn thn, bi v mi loi cy trng thch hp vi mt iu kin kh hu nht nh. Mc d thit k cc h thng iu khin iu kin tiu kh hu bn trong nh knh, nhng s thay i ln ca iu kin kh hu bn ngoi v s chnh lch qu ln ca iu kin kh hu gia bn trong v bn ngoi nh knh nh hng rt ln n cc h thng iu khin cng nh cy trng bn trong nh knh. Kh nng v nh sng, nhit , m, sng mui, tc gi, l nhng yu t kh hu cn c xem xt k cn c xc nh v tr xy dng nh knh cho tng i tng cy trng c th theo k hoch c d tnh. 2.1.2. m Cc khu vc gn vi nhng khu vc c lng nc ln v cc khu vc ma to c m cao; v vy, nhng khu vc trng cy qu dy lm cho tc thot hi nc qua l cy qu nhanh. m cao ca khng kh khng ch nh hng n sinh trng ca cy m cn gy bnh cho cy. Nhiu ngi lm vn xy dng nh knh v mong mun n c hnh dng ging nh cc nh knh khc. iu ny hon ton khng ng. Chn la v xem xt mt cch cn thn iu kin thi tit xc nh v tr xy dng l v cng quan trng v khng th coi thng, vn quan trng nht cn quan tm l cng chiu sng. 2.1.3. nh sng tt Khi xem xt mt ci nh c th hnh dung c thit k nh th no xung quanh nh knh l rt thng thng cho vic thit k mt nh vi y tin nghi v lai b nh knh nhng v tr khng tha ng. Tuy nhin, iu ny nhiu ngi cho rng s sp nhp nh knh nh mt nt c trng trong nh c v yu t thm m v thc t. N to ra mt s ph thuc thch hp cho ni v cng l cch tit km cho vic lm vn trong nh knh v si m gn lin vi h thng ca gia nh. Tuy nhin, vic xem xt ny khng nh hng n tm quan trng c bn ca s sp xp cu trc ti ni n s tip nhn nh sng tt, mc d r rng nu nh knh c s dng ch yu tiu khin v s tiu khin ny mong mun trnh c tng

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nhit n mc khng th chp nhn c vo bui tra v chu s nh hng mt tri bui chiu. nh sng l rt cn thit cho nhiu cng vic trng trt, c bit cho vic nhn ging v to iu kin cho s sinh trng ca nhng cy a sng trong nhng thng ma ng. V vy, y l s la chn c bn v tr cho nh knh nu mun l l tng nu cn thit v phng din tip nhn nh sng, c bit trong nhng thng ma ng. Mt v tr nm pha c nhiu nh sng ca ngy t thng ba n thng mi c th l s m m tht s cho phn ln ma ng khi nh sng l thp.

Hnh 2.1: Kh nng che sng ca hng ro 2 ma khc nhau. 2.1.4. Yu t gi V tr xy dng nh knh c cn thit phi che chn hay khng? Cu hi v nh sng v vic che chn c quan h cht ch vi nhau. Mt nh knh c th c xy dng trong mt vn cnh gn lin vi nhng hng cy cao hoc cc hng ro v tham gia tt vo iu kin nh sng yu. mt vi khu vc khng th trng trt c kt qu tt m khng trng cy che chn Trong nhiu khu vn, ch che chn gi trn thc t khng cn thit v ton b din tch chung khng cn n vn ny. Khng c s hng dn ca t nhin tt hn l to dng cho cy vng k cn, thm ch tt hn so vi li khuyn ca nhng ngi lm vn trong vng, mc d iu ny c th khng phi quan tm. Gi c th ng nhiu mnh khe khng th tnh trc bng cch thi ngi nh hoc i ni hoc to ra cc khu vc no ng mnh m ln pha trnh gi ca cc bc tng v qut. B tr ai chn gi: Cung cp ch che thng c quan tm hn c i vi ton b vn hn l c bit i vi nh knh. Cc quy lut ging nhau c s dng cho c hai. Cc tm che chn cng ngy nay hu nh khng c quan tm. Chng hu nh khng lm ngng gi. Chng ta cn lm lch hng gi ln trn, sau a xung vi mt tc yu hn, i khi to ra s no ng ng k ngay pha sau tm chn.Tt c cc dn chng ca cc nghin cu mi nht cho thy r l mi trng c11

dng tm chn gi 50% l l tng cho vic lm chm tc gi, trnh c s lch hng v s no lon. Cc tm chn ny c hiu lc khong cch gp 10 n 12 ln chiu cao ca tm chn, iu ny c ngha l trong gii hn thc t, nu hng ro chn cao 2,4m s c hiu lc trong khong 24 30m tr li. Vng c kh nng che ti a l khu vc t 5 n 6 ln chiu cao ca hng ro tc l khong 12 15m trong trng hp hng ro cao 2,4m, khong cch khng c che chn cn c quan tm. Mt hng ro cao vi nhiu cy dng cao, v phng din khc, s to nn mt s bo v tt cho mt vng rng ln nhng c th s l vn che chn rt gi to vo ma h.

Hnh 2.2: M hnh chn gi cho mt nh knh n gin 2.1.5. Hng xy dng Xc nh hng xy dng nh knh cng l mt yu t cn thit lin quan n kh nng nhn nh sng v gi. Thng thng xy dng nh theo hng theo hng Nam-Bc l tt nht m bo kh nng nhn nh sng ca nh knh. Tuy nhin cng c nhng nh knh c xy dng khng theo hng Nam-Bc, lc ny th cc lung trng trong nh knh cng nn c xy dng cho ph hp vi hng nhn nh sng lm sao c s phn b nh sng ng u cho cc lung cy trong sut thi gian chiu sng. 2.1.6. Ch nc: Cng nh kh nng cung cp nc ca khu vc xy dng nh knh cng c quan tm. Chng c ngha ht sc quan trng i vi hiu qu cng nh s tn ti ca nh knh c lu di. S dng ngun nc sch l cn thit cho hot ng ca nh knh. Nhng iu kin thun li khc nh in, nhin liu, cht t,... cng nn c xem xt. 2.1.7. Kh nng thot nc ca t: cng rt quan trng trong vic xc nh v tr thit lp nh knh. V tr xy dng nh knh nn t v tr tng i bng phng vi s thot nc trn v di b mt. Xy nh knh trn nhng vng t cng bng phng th nhn cng cng nh cc vt liu khc s di chuyn mt cc d dng hn. 2.1.8. Cc iu kin khc: Cc iu kin v t ai, tng t v r cy cng cn phi xem xt mt cch cn thn.

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Nhm gim bt cc chi ph u t v thun tin cho th trng mang li hiu qu kinh t cao, ngi ta cn quan tm n khong cch ca v tr thit lp nh knh so vi ng giao thng, th trng tiu th, v ngun nguyn nhin liu lin quan,.. Th trng (ni tiu th cc sn phm nng nghip): trc khi u t vo vic kinh doanh bng nh knh, nn xc nh r th trng tiu th, cng nh sc mua v gi c u ra ca sn phm. Gn ng giao thng: tin cho cng vic chuyn ch phn bn, nhn hng v giao cc sn phm th nn xy dng nh knh gn ng chnh. Hu ht cc sn phm t nh knh u c vn chuyn bng xe ch hng hoc xe ti mt s c s hot ng vi quy m ln. Nu hot ng kinh doanh ca nh knh nh mt i l bn l, th phi lp t gn cc v tr cng cng d thu ht c khch hng. Nhng vng quy hoch (Zoning Regulation): trong nhiu vng dn c, khng cho php xy dng nh knh. V vy chng ta cn kim tra li cc khu vc quy hoch i vi mt s vng t bit trc khi mua hoc chuyn nhng t ai phc v cho xy dng nh knh. Nhn cng: phi nh hng c lng nhn cng c th cung cp, trong phn chia thnh ngun nhn cng c kinh nghim v nhn cng cha c kinh nghim. y l yu t quyt nh n tin cng nh hiu qu hot ng ca doanh nghip. Kh nng m rng quy m: nh knh hot ng cn c k hoch m rng quy m trong sau ny. C th lc u ch l mt nh knh c lp, nhng cng phi c k hoch m rng quy m, xy thm thnh nh knh lin tip. Nh vy, y cng l yu t quan trng trong nh hng v pht trin kinh doanh nh knh.

Hnh 2.3: Kh hu

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Hnh 2.4: Hng xy dng

Hnh 2.5: ng i v hng phn x ca nh sng i vi cc loi cu trc hnh dng nh knh khc nhau 2.2. Lp t b khung nh knh cng nh cc loi nh che ph khc: 2.2.1. inh v v lp t b khung nh knh: sau khi xc nh v tr xy dng nh knh, tin hnh nh v v lp t b khung nh knh. Khung nh knh c th c thit k theo cc hnh dng khc nhau: hnh vung, hnh ch nht, hnh lc gic,... Khung sn nh knh hay nh che ph c th c ch to t cc ngun vt liu khc nhau. Cc vt liu c th l st, nhm, g, tre,... trong , khung nhm l loi vt liu c nhiu u im v c s dng nhiu nht. Hin nay, i vi cc doanh nghip sn xut cy ging cng nh cc sn phm rau qu mc qui m cao ngi ta thng s dng loi nh knh c khung sn nhm. Mt s loi nh knh c ch to theo kiu lp sn v c lp t ti ch bng cc ghp ni bulng, vng m, ai c, khng c kt cu phi hn. Trc khi xy dng nh knh, cn phi c mt bng (nn mng) to nn sc chng ca b khung nh. Vic xy dng nn mng c th c tin hnh, nhng thng

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thng cc chn c xy bng b tng. Nn mng c xy dng di ng dy nh v gii hn din tch v c t ti v tr khong gia theo nh v tr ca tr bn. H thng ng nc v ng dy in nn c b tr v lp t trc khi xy dng nn mng nh knh. Lp t cc ng ng ca h thng in nc, xy dng nn mng b tng mt cch bng phng, vung vn cn i hp l l ht sc quan trng ph hp vi b khung sn nh sau ny. Mt s nh knh cn xy dng c nhng bc tng bn (sidewalls) hoc nhng vch che. Vch che c xy dng gia chn v thanh tr bn. Chiu cao ca vch che bn di chn ny khong chng vi chc centimet (cm) v ph khp chu vi ca nh knh. Thng dng bng nhng khi g, gch, than x, hoc c th dng b tng xy thnh vch che chn. Da theo bn v thit k chun b sn, nh du v tr dng nh knh trn mt t, thng ngi ta dng nhng cc nh du c kch thc chnh xc 2,5 x 2,5cm v c chiu di ti thiu l 30cm. ng nh cc u tin vo mt im c khong cch nht nh so vi mt ng thng c nh no nh hng ro, ng i hay mt to nh, v s dng cun thc o bng kim loi xc nh chiu di ca nh knh, sau dng mt cc khc nh du v tr ny, ch s dng cch o t tm n tm cho mi cc. Nh kim tra xem hng cc c nm trn cng mt ng thng vi hng ro hay to nh hay khng, ng thi m bo rng chng theo ng hng nh ban u. Ch rng y l chiu di ca nh knh, l hng ca cc lung cy, do chng phi ph hp vi hng ng Ty hay Nam - Bc theo thit k. S khng khc bit my nu b sai lch mt vi t hng ny qua hng khc so vi thit k nh, tuy nhin, i vi kiu lung ng ty, s tt hn nu b lch v hng bc, cn vi kiu thit k bc nam, b lch v hng ng s tt hn. Vi mt nh knh hnh vung thch hp, tt hn l nn p dng kiu lung chy t ng sang ty cn bng s truyn nh sng vo ma ng v xun. Ti nhng ni xy dng nh knh nhng khng p ng cc yu cu v hng, khng th chn c hng xy tt nht m nh knh phi dng theo c hng ng - Ty ln Nam Bc. Nh vy duy tr lng nh sng phn b u cho cc lung cy vo ban ngy v th chng ta phi c nhng cc b tr cng nh cch sp xp cc lung cy cho ph hp. Tip theo chng ta nn xc nh khong cch hai cc mt cch chnh xc, ng chng chc chn vo t. Vi mt nh knh theo kch thc trung bnh vi chiu di t 2,5 3,2m, cn mt bng di, phng, khng b vnh v mt ng ni v o phng. i vi nh knh di hn th nn s dng cc cc trung gian, kim tra xem thng hng gia cc cc nh v bng cc si dy nh c cng gia hai cc. Mc d vy chng ta cng cn kim tra li ln cui bng phng cc cc tr bng ng ni v (ng thng bng dng bt nc). Cc nh knh nh hn thng c dng mt mc ngang bng c nh, kiu ln vi mt mng xi c th hi nghing v mt pha, theo nh li khuyn ca ca nh sn xut, s to iu kin thun li cho s lu chuyn nuc trong mng. Vi loi nh knh thng mi, c bit l dng nh knh c nhiu gian, th cn phi lp mt mng xi nc m bo cho qu trnh thot nc mt cch nhanh chng theo mng xi v khng chy ngc li qua lp knh khi tri ma.15

Sau , ng nh mt chic inh vo tm ca mi cc, phi cn thn dng thc th ph hp o rng ca nh knh mt cch cn thn ch khng nn phng on. C th s dng loi thc tam gic c to t 3 ming g thng c chiu di 0,9m, 1,2m, v 1,5m (y l loi thc chuyn dng c 1 gc vung v 2 gc nhn). Kim tra li xem chnh xc ca cc gc c to thnh trn thc ny bng ke. Thc tam gic ny nn c t ngay vo ch ng inh mt gc cc v mt cnh nn c bng gch dc theo si dy cng gia hai chn cc. Sau khi cnh kia ca gc vung, t mt si dy dc theo v buc cht vi cc t pha ngoi xc nh rng ca nh knh. Tip tc o dc theo dy v thm cc xc nh chiu rng. Lp li qu trnh ti cc gc cn li, v kim tra 2 cc theo chiu dc, ng thi kim tra xem cc ng cho c bng nhau hay khng. Cng cn thit nn iu chnh s qua mi th n khp vi nhauBy gi th nng cc cc gc ln v ng inh vo tm ca chng. Cui cng t mt si dy bn v cng vo mi cc gc phc ho ra hnh dng/ung nt ca cn nh bng cch s dng cc mu g, hoc dng thm cc, cch pha ngoi nh knh 0,6 0,9m cng vic c th tin hnh trn nn mng ca nh knh m khng c tr ngi bi vic di chuyn cc cc gc v cc dy ra pha ngoi theo yu cu.(Xem hnh 2.6)

Hnh 2.6: nh dng nn mng nh knh (din tch nh knh) 2.2.2. Nn mng: y l mt cng vic rt quan trng c lin quan n rt nhiu yu t, b phn ca nh knh sau ny. Xy dng nn mng nh knh ph thuc vo tng kiu nh tng cu trc nh knh. Vi mt s lai c th ca kiu nh knh Dutch light, ch cn t cc khi trn mt t bng, mc d y khng phi l mt cch thch hp i vi nh knh c s dng lu di, thiu tnh bn vng hay vic ngn s di chuyn ca cc dng nc m trong t xung quanh. y l cch thc t c chp nhn v s dng bi tnh tit kim v kinh t ca n, hoc khi i im dng nh knh ch l a im tm thi. Yu cn ca mt nn mng l tng l phi gi cho nh knh hon ton thng bng v vng chc ngay c khi c gi bo. Yu t ng gi nht, nu c, s ph thuc vo nhiu nhn t, v c bit l ph thuc vo kch thc thc t ca nh knh c dng. Nn nghin cu tht k s dng hoc sch hng dn c th p dng vi nh knh. Cc khi ny c th t (hng) km vi nh knh; hoc thay vo bn c th xy nn mng bng gch hoc b tng c nh cc. i vi nhng nh knh khng chuyn cu trc na gch dy 11 25cm s ph hp, v n thng chnh xc vi rng ca bt k khi nn no. Trong trng hp ny, sau khi xc nh chnh xc ng gia y nh knh, o mt rnh rng 10 23cm v su 18 20cm, hoc su16

hn nu t mi c san bng tip xc vi phn t cha b xi. iu ny khng phi lc no cng thc hin c. Trn 3 phn gch vn, 2 phn ct th, 1 phn xi mng ri tri mt lp dy 8 10cm v nn lp ny cho cht bng cch s dng mt bn phng, nng, s dng mt niv (ng thng bng dng bt nc) mt trn kim tra phng thng xuyn. Trong trng hp cn thit phi xy ton b nn mng bng gch c dy 23cm, nh trong trng hp i im dng dc, hay i vi nhng nh knh ln, rnh nn rng 30 35cm v su 12 15cm, mc d trong nhiu trng hp nn 1/2 gch s vng chc nu c gia c thm bng cc cc chng. Trong mt s trng hp nh knh c th t trc tip ln nn mng m khng cn cc khi nn, trong trng hp ny s cn c bu lng lng vo nn mng ti v tr thch hp, hoc thay vo c th s dng ci chem (bn ging). Lun lun i nn mng kh cng li ri mi bt u xy dng. Trong tt c cc trng hp nn t dy tr li ng v tr c v gi chng cng khi cn c th kim tra xem chng c tun theo kch thc nh nh hay khng. Trc khi xy cc tng i din, nn kim tra li rng v chiu di, bi v gch c khuynh hng khng thng hng, c bit nu chng c xy bi nhng ngi th n khng c kinh nghim. Vic nghin ngm cc quyn catolo v nh knh ch gip chng ta thy mt bc tng pha ngoi hon chnh m khng c quy nh v cc ca, vic ny s dn n nhng bc lng tng tr khi c mt on dc thch hp. Khi t cc khi nn, nn cha v tr ca ngang bng vi mt t, mt s sp xp hp l hn, min l c mt bc ngn bng b tng Nhng iu trn c v khng quan trng, nhng theo thi gian chng s to nn s khc bit rt ln trong vic qun l nh knh. Li khuyn l v tr gn ca nn cao mt cht trnh nuc ma chy vo nh knh, vn ny c th xy ra nu nh nh knh xy trn nn t dc. Ngay c i vi vic xy dng mt bc tung thp th k thut xy cng khc nhau, nhng vic trn ct v xi mng theo t l 3:1, kim tra dy v bng phng ca mi vin gch hay cc khi b tng tht k th ngay c ngi th xy khng chuyn nht cng c th thc hin c. Ch rng nu s dng gch c mt trang tr th mt trang tr nn quay ra ngoi, nu khng th chng s nhanh chng b mt mu.

Hnh 2.7: Xy nn mng nh knh bng b tng

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Hin nay, mt s loi nh knh khng xy dng phn mng bao quanh ton b nh knh m ch xy dng chn cho cc tr nh knh. Loi mng kiu ny tng i n gin, t tn km nhng cng kin c khng km cc kiu nn mng khc.

Hnh 2.8: Xy dng chn tr.

2.2.3 Qu trnh xy dng i vi mt vi loi nh knh yu cu chn tng thp khong 75cm th phi xy chn tng cn thn, nu khng th c th s pht sinh vn sau ny. Rt t khi nh knh dng sn c d kin cho ph hp chn tng s xy. Nhng ngi t lm thng s dng phng php xy chn tng nh knh theo thit k thng thng c nhng tm kim loi trn nh tng chng ng vin nh. gim bt chi ph xy dng nh knh, ngi ta mua li vt liu khung qua s dng, tuy nhin phi cn thn tho ht phn g, qut mt lp sn trc khi bt u xy dng, c bit l phn cn st li ca thanh vin c phi c tho b ht. Nn s dng nhng chic inh c m km, bi v inh bng thp s d dng b g.

Hnh 2.9: Lp rp b khung nh knh dng ng (tube) C rt t trc trc trong vic dng mt nh knh c rp sn, c bit nu c thi gian nghin cu qua s dng nh c cung cp t nh sn xut. Mt s quyn sch hng dn rt chi tit, mi phn c nh du v minh ha bng s r rng vi nhng con s chi tt ca tng b phn. i vi cu trc bng hp kim th18

thng dng cc ct chng v mt mt trn t, ri sau xy mt ct chng, tip tc vi mt mt ri ti mt kia trc khi dng mt ct chng khc,.. Mi nh v h thng thng gi nn cha lm sau cng.

Hnh 2.10: Lp cc ct chng vo tr chnh.

Hnh 2.11: Lp t cc thanh rui v ct chng vo tr chnh.

Hnh 2.12: Lp t b khung nh knh, nh mi che.

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Hnh 2.13: Mng thot nc (xi) c lp bn hng nh knh.

Hnh 2.14: B khung nh knh hon thnh.

Ton b b phn lp knh ca nh knh bng g c lm sn c dng theo mt th t tng t, nhng vn cn s gip bi v cc b phn ny thng nng. Nu lm nh knh bng g trn chn tng t xy, th nn dng khung chnh trc khi t ng vin nh. Khi lp knh, cho d tin trnh khc nhau, ngi ta thng lm phn mi nh trc,. tip n l chn ct chng, cha cc vch gn sau cng trnh trng hp khi gp gi to chng s thi xuyn qua b khung. Mt im rt quan trng khi lm bt c loi nh knh no l ch ni lng cc l thng hi vo ban m, c bit nu chng c lp knh, nu khng th chng c th gy ra nhiu h hng. Nhn mnh s cn thit ca vic c nh nh knh mt cch an ton khng l tha, hy cho xi mng cng li truc khi dng ton b kin trc ng gi. Ch nn lp knh khi thi tit kh, bi v c bt mt tt v bng mt tt u khng th bt kn knh nu nh chn song lp knh b t, mt khc, lm vic vi knh lc cn t l rt nguy him. Vi nh knh bng hp kim, tt c nhng ch ni mng nc hay cc phn chnh khc nn c hn kn bng mt tt hoc nhng vt liu thch hp khc. ch no c mng nc, bm a nc t mi nh xung nn c lp t n ch thot nc hay thm nc ph hp, v khi nh knh c xy dng trn a20

hnh dc c th cn phi xy dng mt con mng dc theo nh knh bn pha cao hn ngn nc r vo nh knh.

Hnh 2.15: Nh plastic ni tip

Hnh 2.16: Nh knh c lp khung kim loi.

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Hnh 2.17: Dng nh knh c lp khung g c kch thc nh (thng trang tr)

Hnh 2.18: Nh knh ta vch bng khung g (trang tr)

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Hnh 2.19: Dng nh plastic khung kim nhm 2 mi khng i xng. 2.3. Cc dng mi lp: 2.3.1. Nh knh (cc vt liu che ph ca loi nh knh ny hon ton c lm bng knh): Vt liu knh cha 70% dioxide silicate (SiO2). Knh c bn cao, thi gian s dng c th ko di 25 nm. Knh trong c kh nng cho nh sng xuyn n 90%. Ngoi ra ngi ta cng s dng loi knh m lm vt liu che ph cho nh knh. Trong vic xy dng nh knh, khung g hoc kim loi c dng ln v gn ln nhng thanh trt g hoc kim loi vi nhng knh gn cht trn . Nhng loi khung sn nh knh bng nhm lm sn cng c cc nh sn xut a chung, v hin nay loi nh knh ny c s dng tng i rng ri. Chu u n mt s ni M, ngi ta cn s dng loi knh m lm mi lp cho nh knh em li nh sng khuych tn, ng nht. Nh mt thc t ni chung, nh knh c sn bn ngoi bng mt lp vi trng mng hoc sn nc trng khi bt u thi tit m p ca ma xun. iu ny gip phn chiu phn ln nng lng bc x ca mt tri, nh ngn nga c s gia tng nhit ln cao trong nh knh. Tuy nhin, lp vi trng ph bn ngoi qu dy c th lm gim cng nh sng xung mc thp khng mong mun. Nhn chung th chi ph xy dng nh knh thng cao hn cc loi nh che ph khc, tuy nhin, i vi s lp t c nh v s dng trn qui m rng ln vi thi gian kinh doanh tng i di th cc kiu nh lp knh ny tr nn u vit hn cc loi nh ph bng nha gi thp nh c m t trong phn sau.

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2.3.2. Nh knh ph bng nha: Nhng khung nh c ph vi cc loi tm nha khc nhau th ph bin i vi nhng cu trc vn nh nh cng nh i vi nhng khu lp t thng mi ln. Mt vi loi vt liu nha sn c, kh nh v khng t cho php xy dng nh knh vi gi thp hn nhiu so vi vic dng knh. Thng thng cc loi nh che ph bng nha ch c xy dng mt cch tm thi hoc cc nh sn xut nh, tr khi xy dng c nh hn bng nhng tm ph gi cao nh nhng tm bng si thy tinh. Nh knh ph bng nha th kn hn nh lm bng knh, do lm gia tng m v s ng nc trn cy c bit vo ma ng. Tuy nhin, vn ny c th c gii quyt bng vic duy tr s thong kh mt cch thch hp bng cch s dng cc h thng iu khin khng kh t ng. Cc loi vt liu thng s dng i vi kiu nh che ph ny nh: polyethylene, nha vinyl, mt s loi vt liu nha tng hp khc, 2.3.2.1 Polyethylene: y l cht liu r nht nhng c thi gian s dng ngn nht. Loi vt liu ny thng hay b hng vo ma h v phi c thay th mt nm mt ln hoc hn; thng thay vo ma thu s dng trong sut ma ng. Polyethylene c kh nng cn tia cc tm lu hn nhng c phn t hn. dy c khuyn co l 0,1 0,15mm. cch ly tt hn v gim chi ph si m vo ma ng, c th s dng loi polyethylene 2 lp. Hai lp ny cch nhau bi mt lp kh c thi cng phng lm ko di tui th ca polyethylene nh hn ch tc hi ca gi v lm gim m v hn ch nc ng bn trong nh che ph. Nh che ph ph bng mt lp polyethylene s mt nhit vo ban m hoc vo ma ng nhiu hn so vi nh c lm bng knh v polyethylene cho php chuyn nng lng nhit t t v cy vo nh che ph d hn nhiu so vi nh knh. Knh ngn hu ht cc bc x hng ngoi trong khi polyethylene th khng cn c tia hng ngoi. Polyethylene c kch thc rng ln n 1,2m. Do , khi lp rp cc vng c gi mnh ngi ta thng s dng li dy hoc vi cho mng polyethylene. i vi vng c kt hp chn nui cc loi gia sc, gia cm th nn lp li thp xung quanh khi rch tm nha.

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Hnh 2.20: Mi nh che ph bng plastic dng vm 2.3.2.2. P.E gn sng (Woven polyethyelene) thng dng cho nhng nh che ph c mi xp c. Vt liu ny c cht U.V, nga c hi nc ng mt trong plastic, loi ny c th cho nh sng xuyn qua n 80%. bn t 5 nm. 2.3.2.3. Polyvinyl Fluozide (PVF) loi vt liu ny c bn trn 10 nm. C kh nng anhsangs xuyn qua rt tt, v c cht chng tia U.V. Loi ny c cht lng tt nh knh. 2.3.2.4. Polyvinyl Chloride (PVC) c bn di hn P.E. Tuy nhin y l mt loi vt liu c tnh tnh in, ht in. Do , thng hp thu cc ht bi nh lm bn vt liu v lm gim kh nng cho nh sng xuyn qua. y l loi vt liu c kh nng hp thu I.R v gi c nhit vo ban m. 2.3.2.5. Ethylene-Vinyl Acerate Copolymers (EVA) l loi vt liu rt cht, bn v t tin nn ngi ta thng t s dng. 2.3.2.6. Polymethyl Methacrylate (Acrylic) l loi vt liu rt tt. Chu ng c vi thi tit, nh hn knh, nh sng vn xuyn qua tt. Loi ny cng gn nh knh, nhng nhc im ln nht ca n l sau thi gian s dng lu di chng d ho vng m v lm cn tr nh sng. 2.3.2.7. Risid sheet plastic (tm nha cng) L loi mng m c, trng, dai, hn hp ca polyethylene v nha vinyl cng c th dng c. Mng ny c th cn bc x mt tri tt hn v vn mm do hn nhit thp vo ma ng so vi polyethylene. Di nhng loi mng nh th nhit t dao ng hn di nha trong cho nn n tt cho cc cy trng trong nh knh vo ma ng. Vic dng hai mnh nhm kp gia tm ph polyethylene cho n c gi chc vo khung em li kt qu l tit kim ng k thi gian v sc lao ng trong cng vic hng nm. 2.3.3. Nh knh ph bng si thy tinh Loi vt liu ny l cc tm pano cng gp np hoc phng bng cc tm si thy tinh gn vo tm nha c s dng rng ri cho vic xy dng nh knh. Si thy tinh th chc, bn, nh v d dng vi a dng v rng, di v dy. Ch nn25

dng vt liu trong, dy 1mm tr ln v nng 1,0 1,5kg/m2 c bit dng cho vic lm nh knh. S dn truyn nh sng ca vt liu ny c xu hng gim dn theo thi gian. Si thy tinh l t nht trong cc loi vt liu m t y. Ngoi ra, trong mt vi trng hp ngi ta cn s dng tn che lp phn mi. Tuy nhin loi ny thng t c s dng. Bi hn ch ca chng v vn iu tit nh sng v nhit bn trong nh knh.

Hnh 2.21: Nh plastic dng vm lin tip.

Hnh 2.22: Nh che ph plastic dng vm lin tip.

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Hnh 2.23: B khung nh plastic lin tip:

Hnh 2.24: B khung nh plastic lin tip

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Hnh 2.25: B khung nh plastic lin tip:

Hnh 2.26: Dng nh plastic vm h khung kim loi.

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Hnh 2.27 : Dng nh che ph c khung tre 2.4. Cc dng lung, mng, chu trng cy s dng trong nh knh: Trong nh knh ngi ta thng trng cy trn lung, chu hoc cc loi gi trng khc: 2.4.1. Mng trng: i vi cc nh knh trng rau, hoa ngi ta thng trang b thm cc mng gi th. Loi mng trng ny c sn xut mt cch chuyn dng, v c trang b cho ph hp vi cc loi cy trng khc nhau. Gi th cha trong cc mng ny c th l t, cc hn hp trn hoc cng c th l cc hn hp gi th nhn to khng cha t. Chng hn, i vi cy c chua, ngi ta cng trng trn cc mng gi th khng cha t m cha mt loi gi th c bit chuyn dng cho cy c chua, t 4 mng trn mi nhp nh knh. Cc mng gi th ny t trn mt mng thot nc ngoi, dng thot v thu hi lng nc ti d trong qu trnh chm sc. u im ca phng php ny l n gin, d vn hnh, mang li: o Nng sut cy trng cao o m bo s dng ti a din tch nh knh o To iu kin gi sch mi trng ti a o Cy sch bnh o Chi ph thp o H thng thot thu hi nc thi hon chnh

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Mng trng c l thot nc

Mng cha nc thi

kp

Hnh 2.28: Cu trc ca mng gi th trng c chua. 2.4.2. Lung trng: Cy trng trong nh knh cng c th c trng trn lung. Cc lung trng ny cng c chun b tng t nh cc lung cy trng ngoi ng rung. C cc dng lung trng khc nhau, v vic la chn kiu lung trng cng ph thuc vo i tng cng nh iu kin mi trng v kh nng iu tit cc iu kin ca nh knh.

Hnh 2.29 : Lung trng cy 2.4.3. Chu trng cy: 2.4.3.1. Khay nng trng cy: V c bn y l nhng khay bng g, nha hoc kim loi nng vi nhng l thot nc di y. Chng c tc dng gieo ht hoc to r cho cnh gim v chng cho php di chuyn cy con y mt cch d dng khi cn. Nn dng cc30

loi g bn nh tng, bch hoc g lm loi chu nng. Cc loi chu nha v m km c nhiu kch thc khc nhau. C 2 loi c th xp lng vo nhau v th ch cn ni bo qun tng i nh. Trong xu hng c gii ha, nhng flat ln c vi chc cm c lm thnh nh nhng tm pa-let c th di chuyn c bng xe nng sau khi trng cy hoc cnh gim c r.

Hnh 2.30: Khay nha m cy.

Hnh 2.31: Loi gi trng cy theo . 2.4.3.2. Chu t st Nhng chu hoa bng t st quen thuc lu nay vn c dng trng cy con d thm, d mt nc v nng. Chng d b v dng hnh trn ca chng khng c kinh t v ch . Sau khi s dng lin tc, s tch ly mui gy c gia tng nn cn phi ngm trong nc trc khi dng li. Tuy nhin, chng c th c tit trng bng hi, c th dng li v l mt loi chu ph bin.

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2.4.3.3. Chu nha Chu nha trn v vung c nhiu tin li; chng c th dng li, nh v t chim din tich ct gi, bo qun v chng c th xp chng ln nhau v khng thm. Tuy nhin, mt s loi d v v cn di chuyn cn thn mc d cc loi khc lm bng polyethylene th mm do v kh chc. Cc chu vung cng c lm thnh nhng ti 8 hoc 12 ci d vn chuyn hn. Cc chu nha (v chu nng) khng th tit trng bng hi c nhng mt s nhng tc nhn gy bnh cho cy thng thng c th c loi b bng cch ngm nc nng 70o C trong 3 pht m khng lm hng nha.

Hnh 2.32: Cc dng chu nha trng cy trong nh knh. 2.4.3.4. Chu bng si Than bn, g v c b sung phn bn c p thnh nhng dng chu khc nhau: hnh trn hoc vung, vi kch thc t 5 10cm. Chng kh v s gi c lu di. Nhng chu ny c th b vi khun lm cho thi ra v c b sung vo t, cung cp thm cho cy trong qu trnh trng. Chu than bn c cng dng tt nht trng cy trong mt thi gian ngn v sau t vo mt chu ln hn hoc a ra vn. Chu than bn trng trong mt thi gian di s hng v m khng thay i v c th b v vn khi di chuyn. Trong khi , nu khng gi m cho chu th r s khng bm vo thnh chu v s pht trin theo hnh xon c. Nhng chu c kch thc ln c lm bng si c trn nha ng c th dng cho vic trng cy ging. Nhng chu ny c th c s dng trng trc tip v chng cng hy trong t.

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2.4.3.5. Cc khi than bn hoc si Cc khi nguyn liu rn (c khi c l sn) tr nn ph bin nh mt mi trng gieo ht hoc mi trng to r cho cnh gim, c bit cho nhng loi hoa nh cc v trng nguyn. Phn bn thng c b sung trc tip vo nguyn liu trng. Mt loi c lm bng than bn nn cht v s n ra khi thm nc, v nh gim cnh hay gieo ht. V c bn nhng khi ny tr thnh mt phn ca trng cy v t vo trong t cng vi cy. Nhng khi ny khng ch thay th chu m cn l hn hp dng nhn ging. 2.4.3.6. Giy p parafin v cc chu styrofoam Khi nhng loi ny c c l thot nc, chng lm thnh nhng chu tm thi cho vic trng v cy chuyn cy con. Loi gi trng cy ny tng i r v nh, v cn khng gian bo qun nh. 2.4.3.7. Chu bng giy n ph nha ng V phng din thng mi nhng loi ny c mt s c v l nhng chu trng cy tm thi thch hp. Chng r, chc, nh v d xp chng ln nhau. Chu c th c lm bng giy xy dng c x l nha ng, un cc mnh giy ng kch c thnh nhng ci ca hnh vung, y m bng cch t chng vo nhng ngn gi l st trng c th m c trn mt t. 2.4.3.8. Chu kim loi Hng trm hng ngn cy m c trng v bn mi nm trong nhng hp kim loi vi cc kch c khc nhau. Thng nhng hp ny c tn dng t cc nh my hp, nh hng ln v l bnh m. Nhng hp ny cng c th dng chun b cho trng cy. C loi c un ln sng v lm nh dn xp chng ln nhau v c c l thot nc. Chng c trng men lm chm s g st. Cc my trng cy c pht trin tn dng nhng hp ny, vi my ny mt ngy c th trng c trn 10.000 cnh gim hoc cy con mt cch nhanh chng. Cy trng c di chuyn mt cch d dng bng nhng hp c lm nh dn bng cch ln ngc v tin ren. Cc hp kim loi khng c lm nh dn phi c ct bt mt mt bng ko ct hp hoc ko ct tn c th di chuyn cy. nhng vng c nhit ma h cao, s dng nhng hp sng mu (trng hoc nhm) c th thc y s pht trin r bng cch trnh s ph hy nhit cho r m thng gp cc hp mu ti s hp thu nhit ng k nu phi ngoi nng. Ngoi ra, nhit ca t trong cc hp kim loi c chiu hng cao hn trong cc hp nha. 2.4.3.9. Cc ti polyethylene Cc ti polyethylene nh c cc l c c di thot nc c th c y cc vt liu gi th xp to r nh trn chu vi vermiculite v c t trn gi nhn ging vi ming ti m. Mi mt cnh gim ca cc loi cy d ra r nh cc c gim vo mi ti. Nhng ti ny sau c th c t di mn che v chm sc cho n khi cnh gim ra r, cng cp th c chuyn vo ti trng hoc trng trn cc lung sn xut.

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Hnh 2.33: m cy trong ti polyethelene. 2.5. Cc loi gi th trng cy trong nh knh: C nhiu loi nguyn liu s dng lm gi th trng cy, chng bao gm nhng loi nguyn liu sau: 2.5.1 Yu cu chung ca gi th trng Vic la chn gi th trng l mt trong nhng vn quan trng nht lin quan n hiu qu ca sn xut. Mi trng khng ch nh hng n cc bin php k thut chm sc cy trong nh che ph, m cn nh hng n chi ph vn chuyn v s hi lng ca khch hng sau khi mua bn. Mi trng sinh trng p ng nhng chc nng quan trng chung trong s sinh trng v pht trin ca cy trng nh: - S thng thong v kh nng gi m: gi th trng phi m bo c m thch hp cho s pht trin ca cy, v ng thi c kh nng duy tr c khng kh khuch tn trn b mt cho s hot ng v pht trin ca r cy. Nu khng c s lu thng trao i khng kh cho r cy th s sinh trng ca cy s b chm li v do , s lm chm tr thi v thu hoch v khng p ng nhu cu theo thi im ca th trng. - Kh nng gi phn: gi th l mi trng cung cp dinh dng cho cy trng. pH ca gi th trng cn c m bo trong sut qu trnh sinh trng ca cy m bo cho cy ht c dinh dng. Thng thng cc loi cy trong nh che ph yu cu pH khong 5,5 6,5. y cng l pH cn thit c th gi li dinh dng trong gi th v phn gii chm cung cp dn cho cy. - Gi cy trng ng vng: gi th trng cy cn phi c rn gi cho cy ng vng trn gi th. Nhng loi gi th nh c th khng to cho cy th ng vng trn gi th.

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- Gi th c th ti s dng v c gi tr s dng: nhng gi th m sau mi v trng c th tn dng ring l hoc kt hp vi mt vi loi vt liu khc trng cy cho v sau. 3.5.2 Thnh phn ca gi th: Hin nay mt s loi gi th hn hp c trn t cc thnh phn, trong c mt thnh phn ch yu l t. t c trn vi cc vt liu khc to thnh mt gi th tng hp thch hp vi yu cu ca tng loi cy. Mi trng khng t l cc loi gi th c lm t cc vt liu hu c v v c, c th lm t xc b ca ng thc vt nh x da, tru hun, dn si, kt hp vi mt s loi phn hay bt c xay t xc b ng vt nh bt c, v c hn, Sau y l c im gi th t v mt s loi gi th khng t ph bin: 2.5.2.1 t: t bao gm l mt hn hp c 3 pha, pha rn, lng v kh. cy pht trin thch hp nhng vt liu ny phi c t l thch hp. Pha rn ca t gm c dng v c v hu c. Phn v c bao gm phn cn tn d li ca m sau khi phn hy do cc qu trnh bin i ha l ca thi tit. Cc thnh phn v c nh vy khc nhau v kch thc t ht si cho n cc ht keo kh nh ca t st, kt cu ca t c xc nh bng t l tng i ca cc ht c kch thc khc nhau. Cc ht th to c tc dng chnh nh mt khung cho cc phn cn li ca t, trong khi phn t st keo ca t c vai tr nh ni d tr - cht dinh dng m cy c th hp thu c. Phn hu c ca t bao gm c sinh vt sng v cht. Cn trng, giun, nm, vi khun v r cy thng cu thnh dng cht hu c sng, trong khi nhng phn cn li ca ng vt v cy cc giai on phn hy khc nhau to thnh nguyn liu hu c cht. Phn cn li sau khi mc ra (c gi l t mn) rt keo, gip gi nc v cht dinh dng cho cy. Phn lng ca t, dung dch t, c hnh thnh t nc c cha cc khong cht ha tan vi lng khc nhau cng nh O2 v CO2. Cc nhn t khong, nc v c th mt t CO2 c cy hp thu t dung dch t. Phn kh ca t quan trng i vi s pht trin ca cy trng. Trong t b nc v thot nc km, nc thay th kh trong t m n gip cung cp oxy cho cy cng nh vi sinh vt hiu kh chng tn ti. Kt cu ca t da vo t l tng i ca ct (ht c ng knh 2-0,005mm), ph sa (ht c ng knh 0,05-0,002mm) v t st (ht c ng knh