Zzs0ubqv8znbh Hien-phan Huu Co

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  • 578

    PHN HU C TRONG SN XUT NNG NGHIP BN VNG VIT NAM

    Bi Huy Hin1

    Tm tt

    Bi vit ny cp n cc ni dung lin quan n c s khoa hc, tnh hnh sn xut v tiu th cng nh cng tc qun l cc loi phn hu c trn th trng Vit Nam. Ni dung ca bi vit bao gm 4 phn chnh, l: i) Phn loi v tiu chun; ii) Gi tr s dng; iii) Tnh hnh sn xut v tiu th v iv) nh hng pht trin sn xut v s dng phn hu c. Trong phn phn loi v tiu chun phn hu c c th c cc nhm phn hu c nh: phn hu c truyn thng (phn chung, phn rc, than bn, phn xanh, cc loi phn hu c khc) v phn hu c cng nghip (phn hu c, phn hu c khong, phn hu c sinh hc, phn vi sinh, phn hu c vi sinh), trong phn ny ngoi u im cng a ra mt s hn ch ca loi phn ny. i vi gi tr s dng bi bo a ra 3 vai tr chnh, l: i) Cung cp cht dinh dng cho cy trng; ii) Ci to v nng cao ph nhiu ca t v iii) Nng cao cht lng nng sn. nh gi c s lng cc loi phn hu c c sn xut v cng tc qun l nh nc cc khu nh: khoa hc; sn xut v cht lng; iu kin v k thut sn xut; kinh doanh v lu thng trn th trng; s dng phn hu c cho cc loi cy trng. nh hng pht trin sn xut v s dng phn hu c phi da trn chin lc pht trin nng nghip Vit Nam giai on 2011-2020.

    T kha: Phn hu c, phn chung, phn xanh, than bn, phn hu c khong, phn hu c sinh hc, phn vi sinh, sn xut, s dng, qun l phn bn.

    M u

    Cht hu c trong t l cht c hnh thnh do s phn hu xc thc vt nh thn, l, r, v.v..., c th vi sinh vt (VSV) v ng vt t. VSV phn gii cht hu c to ra nhm cht mn khng c trng, chim 10-20% tng s, gm cc hp cht cc bon, hidrocacbon, axit hu c, ru, este, anehit, nha,... cung cp thc n cho thc vt; kch thch, c ch tng trng; cung cp khng

    1 Tng bin tp Tp ch Nng nghip v PTNT

  • 579

    sinh v vitamin. Nhm cht mn in hnh gm nhng cht hu c cao phn t, phc tp c to ra do qu trnh mn ha xc thc vt, VSV, ng vt. Axit humic, axit funvic, humin, unmin chim khong 80-90% tng s. Cht hu c l mt ch tiu quan trng ca ph nhiu t v lin quan vi thnh phn l, ha v sinh hc t.

    Trc cng nguyn hn 2000 nm loi ngi bit dng phn hu c bn rung ci to t, nng cao nng sut cy trng. Theo Phratus (372-287 trc cng nguyn) phn hu c c phn cp cht lng nh sau: Tt nht l phn ngi (phn bc) v sau ln lt l cc loi phn ln, d, cu, b ci, b c v km hn c l phn nga.

    Du n ngi Vit Nam bit s dng phn hu c bn rung c L Qu n (1773) vit trong cun Vn i Loi Ng ghi li t sch T Dm Yu Thut: "Php lm tt rung th trc hy nn trng u. u xanh tt hn, th n u nh v vng (h ma). Cc th y u trng trong thng 5 thng 6. n thng 7 thng 8 thu hoch xong, cy lt p xung, lm rung ri trng la th ma xun nm sau mi mu thu c vi chc t thc. Nhng cy u, vng vi lm phn nh th bn rung tt ngang vi phn tm v phn ngi". c bit v tr bo du dng lm phn hu c bn cho cy trng c xc nh t nht vo gia th k 19. Vic lm phn (compost) bn rung nc ta xut hin t bao gi cha r. Song vo u th k 20 ngi ta bit dng phn hoai bn cho ch, c ngha l qua qu trnh .

    Bn cnh nhng kt qu nghin cu v phn hu c (phn chung, phn bc, phn xanh, phn vi sinh vt) c nhiu phong tro c v ngi nng dn sn xut v s dng phn hu c, nh: Phong tro sch lng tt rung; Phong tro rng in thanh, bin bo du, i ct kh v phong tro chung ln 2 bc, h x 2 ngn, v.v...

    1. Phn loi v tiu chun phn hu c

    Phn hu c c chia thnh 2 nhm: i) Phn hu c nh nng (truyn thng) v ii) Phn hu c cng nghip (hu c khong, hu c sinh hc, phn vi sinh v hu c vi sinh).

  • 580

    1.1. Phn hu c truyn thng

    Phn hu c truyn thng l loi phn c ngun gc t cht thi ca ngi, ng vt hoc t cc ph ph phm trng trt, chn nui, ch bin nng, lm, thy sn, phn xanh, rc thi hu c, cc loi than bn c ch bin theo phng php truyn thng. C th chia phn hu c truyn thng ra lm 4 nhm: i) Phn chung; ii) Phn rc; iii) Than bn v iv) Phn xanh.

    i) Phn chung: c u im l cha y cc nguyn t dinh dng a, trung v vi lng m mt loi phn bn v c khng c c. Ngoi ra, phn chung cung cp cht mn lm kt cu ca t tt ln, ti xp hn, b r pht trin mnh, hn ch nc bc hi, chng c hn, xi mn. Tuy nhin, phn chung cng c nhc im nh: hm lng cht dinh dng thp nn phi bn lng ln, i hi chi ph vn chuyn cao, ngoi ra nu khng ch bin k c th mang n mt s nm bnh cho cy trng.

    Phn chung thng c nh nng t sn xut ch bin. Phng php phn chung c tin hnh nh sau: Phn chung xp thnh lp rng nn cht n khi ng phn cao 1,5-2,0 m. Trt kn bn, gia chc mt l hnh phu ti nc. t 2 n 6 thng. Song thng thng, nn phn chung vi t bt, vi ln (bt c loi phn ln no, t l 2%), c th thm vi (3-5%) cho phn nhanh hoai hn, bt chua, cc vi sinh vt hot ng thun tin hn.

    ii) Phn rc: Loi phn ny lm t rm, r; thn l cc cy ng, u, , v lc, tru, b ma, v.v... cht thnh on ngn 20-30 cm, c th ngm nc vi long 2-3 ngy trc khi . Phng php phn rc c tin hnh nh sau: phn rc xp thnh lp v c 30 cm rc mt lp vi bt. Trt bn, khong 20 ngy, ri o li rc phn ln men (phn bc, phn chung, phn ha hc nh m, ln) vi t l 20%. Xp cao, li trt bn, h l ti thng xuyn. 45-60 ngy v c th dng bn lt, cn lu hn na c th dng bn thc. Ty theo nguyn liu v k thut , thnh phn trung bnh ca phn rc l %: 0,5-0,6 N; 0,4-0,6 P2O5; 0,5-0,8 K2O; 3-6 CaO.

    iii) Than bn: Trong qu trnh cu to a cht, mt s rng cy b ph sa vi lp lu ngy, phn gii ym kh, to thnh than bn. Dng than bn c phi kh n chung, hoc c th

  • 581

    dng ch bin phn rc, lm cht t, cht ci to t. Than bn thng thnh khng dng trc tip lm phn bn, ch phn rc hoc n chung; than bn h thnh c phn gii cao (>50%) v pH t 5,5 tr ln c th bn trc tip, nht l dng lm cht ci to l tnh t; than bn chuyn tip l loi trung gian.

    C 2 ch tiu vt l l sc cha m v mc phn gii nh gi cht lng than bn phc v cho sn xut phn bn. Kt qu nghin cu ca Vin Th nhng Nng ha giai on nm 2002-2003 vi 224 mu than bn 3 vng trong nc ta cho thy:

    - Hu ht cc mu than bn u c m cao, trung bnh l 42,1%, cao nht l: 58,0% v thp nht l: 17,9%, trong , min Bc l 30,7%; vng duyn hi Nam Trung b, ng Nam b, Ty Nguyn l 48,5% v ng bng sng Cu Long 28,2%. Do m cao nn nu s dng than bn lm phn bn th phi tn chi ph sy.

    - Cc mu than bn u kh nhuyn, mc phn gii trung bnh l 35,3% khi lng mu l nh hn 0,2 mm; cao nht l 44,8% v thp nht l 25,3% v thch hp cho sn xut phn bn. Mc phn gii cc m l tng i ging nhau v cng xung su th kh nng phn gii cng cao.

    Quy trnh cng ngh sn xut phn bn trn nn than bn ph bin l: Than bn phi kh, nghin nh, phi trn vi (nu pH thp), ph gia, vi sinh vt, sau mt thi gian ri ng gi thnh phm. Ty theo i tng t v cy trng m c th thay i t l mn, N, P2O5, K2O, s lng vi sinh, v.v trong qu trnh phi trn cho ph hp. Bn phn t ngun gc than bn c tc dng ci to t tt song khi lng ln do hm lng cht dinh dng thp.

    iv) Phn xanh: Phn xanh l tn gi chung cc cy hoc l cy ti c hay vi thng xung t bn rung. ng thi vi tc dng lm phn bn, cy phn xanh c th ph t, chng xi mn, bo v t v lm cy che bng.

    Trong qu trnh phn gii ca cy phn xanh (vi trong t) nht l iu kin ngp nc, thng pht sinh ra nhiu hp cht c hi i vi cy nh H2S, axit butiric, CH4, C2H2, v.v... do , cn bn vi, ln km theo hn ch. Phng php ch bin phn xanh thng l trn vi t bt, phn ln, phn chung, trt kn bn, khong 1 thng.

  • 582

    v) Cc loi phn hu c khc: Phn bc c cht lng cao, nhng cn k hoc st trng trc khi dng. Bnh qun 1 ngi ln thi ra trong 24 gi l 133 g phn ti, gm c 25 g cht kh, 2 g N, 4,5 g tro, 1,35 g P2O5 v 0,64 g K2O. Phn gia cm c th l phn g, vt, ngan, ngng, b cu. T l % trong phn ti ca cc gia cm bin ng nh sau: Nc: 56,0-77,5%; N: 0,55-1,76%; P2O5: 0,54-1,78%; K2O: 0,62-1,00%; CaO: 0,84-2,40%; MgO:

    0,20- 0,74%.

    vi) Bn ao, bn h, bn sng c hm lng mn trung bnh l: 4,90% (dao ng trong khong 1,65 14,90%), N tng s: 0,23% (dao ng 0,11 0,52%), P2O5 tng s: 0,29% (dao ng 0,21- 0,48%), K2O tng s: 0,40% (dao ng 0,13-0,70%), H2S trung bnh l 7,1 mg/100 g bn (dao ng 3,4 -13,6 mg/100 g) nn c th bn cho cy trng.

    vi) Nc ph sa: Nh chng ta bit thut ng Ph sa l ch ht t c kch thc t th n mn do b cun theo cc dng chy (sng, sui) v c lng ng ven sng, ca sng hay gn b bin. Nc sng Hng cha trung bnh 0,5 kg/m3 ph sa lc bnh thng v n thng 6, khi bt u c l th ln 1,8 kg/m3 v l to c th n 3,5 kg/m3. Thnh phn ph sa sng Hng nh sau: pH 7,4-7,6; mn 0,84-1,36%; N tng s 0,10-0,15%; P2O5 tng s 0,13-0,17%; K2O tng s: 0,95- 1,43%. Nh vy s dng nc ph sa ti cung cp cho cy trng, cho t mt lng cht hu c v mt s cc nguyn t dinh dng.

    vii) Kh du: l b cn li sau khi ht p ly du. Ty theo thnh phn ca mi loi kh du m nng dn s dng nh loi phn bn hu c bn vo t cung cp dinh dng cho cy trng.

    vi) Tro: Tro l cht cn li ca mt s vt sau khi chy ht v thng c mu xm. Trong nng nghip mt s nguyn liu thc vt nh cy: sn, bng, ng, l da, mt ca, v.v... sau khi b t c t l tro v cht dinh dng kh cao.

    1.2. Phn hu c cng nghip (phn hu c ch bin, phn hu c khong, phn hu c sinh hc, phn vi sinh, phn hu c vi sinh)

    Phn hu c cng nghip l mt loi phn c ch bin t cc ngun hu c khc nhau to thnh phn bn tt hn so vi bn nguyn liu th ban u. Hin nay c th chia ra 5 loi phn

  • 583

    hu c cng nghip, l: phn hu c, phn hu c khong, phn hu c sinh hc, phn vi sinh, phn hu c vi sinh.

    i) Phn hu c ch bin: l loi phn bn c sn xut ch yu t cc ngun nguyn liu hu c vi tiu chun nh sau: m i vi phn bn dng bt khng vt qu 25%; hm lng hu c tng s khng thp hn 22%; hm lng m tng s (Nts) khng thp hn 2,5%; pHH2O (i vi phn hu c bn qua l) trong khong t 5-7.

    ii) Phn hu c khong: l loi phn c sn xut t nguyn liu hu c phi trn thm mt hoc nhiu yu t dinh dng khong, trong c t nht mt yu t dinh dng khong a lng. Loi phn ny c ch bin t cc nguyn liu hu c khc nhau (than bn, mn rc thi thnh ph, ph phm nng nghip, cng nghip...) phi kh, nghin nh, t nhin. Sau mt thi gian a phi trn vi phn khong cc t l khc nhau. Tiu chun bt buc ca loi phn ny nh sau: Hm lng hu c tng s khng thp hn 15%; m i vi phn bn dng bt khng vt qu 25%; hm lng Nts + P2O5hh + K2Ohh; Nts + P2O5hh; Nts + K2Ohh; P2O5hh + K2Ohh khng thp hn 8%.

    iii) Phn hu c sinh hc: l loi phn c sn xut t nguyn liu hu c theo quy trnh ln men c s tham gia ca vi sinh vt sng c ch hoc cc tc nhn sinh hc khc. Loi phn ny c ch bin t cc nguyn liu hu c khc nhau (than bn, mn rc thi thnh ph, ph phm nng nghip, cng nghip...) phi kh, nghin nh, ln men vi vi sinh vt c tuyn chn.

    Tiu chun ca phn hu c sinh hc nh sau: Hm lng hu c tng s khng thp hn 22%; m i vi phn bn dng bt khng vt qu 25%; hm lng Nts khng thp hn 2,5%; hm lng axit humic (i vi phn ch bin t than bn) khng thp hn 2,5% hoc tng hm lng cc cht sinh hc (i vi phn ch bin t ngun hu c khc) khng thp hn 2,0% hoc pHH2O (i vi phn hu c sinh hc bn qua l) trong khong t 5-7. Nu phn c b sung cht iu ha sinh trng th tng hm lng cc cht ny khng vt qu 0,5%.

    iv) Phn vi sinh: l loi phn trong thnh phn ch yu c cha mt hay nhiu loi vi sinh vt sng c ch bao gm: nhm vi sinh vt c nh m, phn gii ln, phn gii kali, phn gii

  • 584

    xenlulo, vi sinh vt i khng, vi sinh vt tng kh nng quang hp v cc vi sinh vt c ch khc vi mt ph hp vi quy chun k thut ban hnh l mt mi chng VSV c ch khng thp hn 1 x 108 CFU/g (ml).

    Ty theo cng ngh sn xut ngi ta c th chia phn vi sinh thnh hai loi: a) Phn vi sinh trn nn cht mang kh trng c mt t bo vi sinh hu ch > 109 VSV/g (ml) v mt VSV tp nhim thp hn 1/1.000 so vi VSV hu ch. Phn bn dng ny c s dng di dng nhim ht, h r hoc ti ph vi liu lng 1-1,5 kg (lt)/ha canh tc v b) Phn vi sinh trn nn cht mang khng kh trng c sn xut bng cch tm nhim trc tip sinh khi VSV hu ch vo c cht khng cn thng qua cng on kh trng nhm tiu dit cc VSV c sn trong c cht. Phn bn dng ny c mt VSV hu ch >106 VSV/g (ml) v c s dng vi s lng t vi trm n hng ngn kg (lt)/ha.

    Trn c s tnh nng tc dng ca cc chng loi VSV s dng, phn bn VSV cn c gi di cc tn:

    - Phn VSV c nh nit (phn m vi sinh, nitragin) cha cc VSV sng cng sinh vi cy b u, hi sinh trong vng r cy trng cn hay t do trong t, nc c kh nng s dng nit (N) t khng kh tng hp thnh m cung cp cho t v cy trng.

    - Phn VSV phn gii hp cht pht pho kh tan (phn ln vi sinh, photphobacterin) sn xut t cc VSV c kh nng chuyn ha cc hp cht pht pho kh tan thnh d tiu cho cy trng s dng.

    - Phn VSV kch thch, iu ha sinh trng thc vt cha cc VSV c kh nng sn sinh hot cht sinh hc c tc dng iu ha, kch thch qu trnh trao i cht ca cy.

    - Phn VSV c cha cc chng VSV i khng vi khun/vi nm gy bnh vng r cy trng cn.

    - Phn VSV a chng, phn VSV chc nng c cha hn hp cc VSV c kh nng c nh nit, phn gii pht pht kh tan, sinh tng hp hot cht kch thch sinh trng thc vt v i khng vi khun/vi nm gy bnh vng r cy trng c tc dng cung cp dinh dng v nng cao hiu qu s dng phn khong, ng thi c kh nng hn ch bnh vng r cy trng do vi khun

  • 585

    hoc vi nm gy ra, qua nng cao nng sut nng sn v hiu qu kinh t.

    v) Phn hu c vi sinh: l loi phn c sn xut t nguyn liu hu c c cha t nht mt chng vi sinh vt sng c ch vi mt ph hp vi quy chun k thut ban hnh, c th nh sau: hm lng hu c tng s khng thp hn 15%; m i vi phn bn dng bt khng vt qu 30%; mt mi chng VSV c ch khng thp hn 1 x 106 CFU/g (ml).

    i vi tt c cc loi phn hu c cng nghip, cc ch tiu nh lng bt buc trong phn bn nh sau: asen (As) khng vt qu 3,0 mg/kg (lit) hoc ppm; cadmi (Cd) khng vt qu 2,5 mg/kg (lit) hoc ppm; ch (Pb) khng vt qu 300,0 mg/kg (lit) hoc ppm; thy ngn (Hg) khng vt qu 2,0 mg/kg (lit) hoc ppm; mt t bo vi khun Salmonella khng pht hin trong 25 g hoc 25 ml mu kim tra (CFU).

    1.3. Hn ch ca phn hu c

    Ngoi nhng u im th phn hu c cng c nhng nhc im nh hm lng cht dinh dng thp nn phi bn lng ln, i hi chi ph ln vn chuyn v nu khng ch bin k c th mang n mt s nm bnh cho cy trng, nht l khi ch bin t mt s loi cht thi sinh hot v cng nghip. Cc vi sinh vt gy hi c trong phn bn gm: E. coli, Salmonella, Coliform l nhng loi gy nn cc bnh ng rut nguy him hoc nhim th cp do c cha cc kim loi nng hoc vi sinh vt gy hi vt qu mc quy nh.

    2. Gi tr s dng ca phn hu c

    Phn hu c ni chung c u im l cha y cc nguyn t dinh dng a, trung v vi lng m khng mt loi phn khong no c c. Ngoi ra, phn hu c cung cp cht mn lm kt cu ca t tt ln, ti xp hn, b r pht trin mnh, hn ch mt nc trong qu trnh bc hi t mt t, chng c hn, chng xi mn.

    Vo nhng nm ca thp k 60 th k 20 do ngun phn khong c hn nn s dng phn chung bnh qun hn 6 tn/ha/v. Trong giai on 15 nm (1980-1995) vic sn xut v s dng phn

  • 586

    hu c c gim st, nhng t nm 1995 li y do yu cu thm canh, do s khuyn khch sn xut, s dng phn hu c c phc hi, nn s lng phn hu c c sn xut, s dng tng ln ng k. Kt qu iu tra ca Vin Th nhng Nng ho mt s vng ng bng, trung du Bc b v Bc Trung b cho thy bnh qun mi v cy trng bn khong 8-9 tn/ha/v. c tnh ton quc sn xut, s dng khong 65 triu tn phn hu c/nm.

    Bng 1. Hm lng tiu chun cc nguyn t dinh dng trong nguyn liu hu c (theo IPNI)

    Cht hu c* Nc (%)

    % cht ti

    C N P K Ca

    Phn bc (Human feces) Phn i gia sc(Cattle feces)

    Phn ln (Pig feces) Phn ti ca i gia sc (Fresh cattle manure)

    Phn ca i gia sc (Composted cattle manure)

    Phn ln (Pig manure) Phn gia cm (Poultry manure)

    Phn rc thi ngu (Garbage compost)

    Bn t nc thi(Sewage sludge)

    Cht thi ca ma ng sau khi lc ng thnh bnh (Sugarcane filter cake)

    Bnh ht thu du (Castor bean cake)

    -

    -

    -

    60

    35

    80

    55

    40

    50

    75-80

    10

    -

    -

    -

    8-10

    30-35

    5-10

    15

    16

    17

    8

    45

    1,0

    0,3

    0,5

    0,4-0,6

    1,5

    0,7-1,0

    1,4-1,6

    0,6

    1,6

    0,3

    4,5

    0,2

    0,1

    0,2

    0,1-0,2

    1,2

    0,2-0,3

    0,5-0,8

    0,2

    0,8

    0,2

    0,7

    0,3

    0,1

    0,4

    0,4-0,6

    2,1

    0,5-0,7

    0,7-0,8

    0,3

    0,2

    0,1

    1,1

    -

    -

    -

    0,2-0,4

    2,0

    1,2

    2,3

    1,1

    1,6

    0,5

    1,8

    * Ghi ch: + kg cht dinh dng trn 1 tn hu c ti = % hm lng dinh dng x 10; + Ngoi cc nguyn t dinh dng a lng N, P, K trong phn chung c cc cha cc nguyn t dinh dng vi lng. Trong 10 tn...