TRNG I HC CN TH

KHOA NNG NGHIP & SINH HC NG DNG

B MN KHOA HC T

BI THU HOCH

CHT HU C TRONG T

Chuyn : NH HNG CA CHT HU C N VT L T V MT S NGHIN CU V HIU QU CA PHN HU C N NNG SUT CY TRNG

Cn b hng dn

Nhm thc hin

GS.TS V Th Gng

Trn Anh c

M1214007

Trn Hoi Tm

M1214011MC LC

1M U

21. TNG QUAN V PHN HU C

21.1. Khi nim v cht hu c trong t

31.2. Ngun gc cht hu c trong t

41.3. S chuyn ha cht hu c trong t

52. TNG QUAN GIA PHN HU C V L HC T

52.1. Cu trc t v bn on lp

92.2. Dung trng

112.3. Kh nng gi nc

142.4. Mu t

162.5. xp

183. MT S NGHIN CU V HIU QU CA VIC S DNG PHN HU C LN MT S CY TRNG

183.1. Tc dng cung cp cht dinh dng cho cy trng

193.2. Hiu qu ca phn hu c trn trng lng tiu kh

213.3. Hiu qu ca phn hu c b bn ma v Tithonia trong ci thin nng sut rau hng cy

223.4. Hiu qu ca phn hu c - Vi sinh trn nng sut v cht lng rau xanh trng trn t ph sa ti tnh Long An (Theo TC Khoa hc 2011:18b, Trng HCT)

233.5. Hiu qu ca phn hu c b bn ma v Tithonia trong ci thin nng sut cam

25KT LUN

26TI LIU THAM KHO

M U

Tng cht hu c trong t gip tng s n nh ca on lp (tng s lin kt cc ht st nh thnh nhng ht to hn), nh t c thong kh hn, gim s nn d (Rachman et al., 2003). Kt qu nghin cu trc y cho thy cung cp thm phn hu c gip tng ph nhiu t qua tng hm lng cht hu c trong t, tng P hu dng, N hu c dphn hy, tng cng kh nng hp ph cation trong t (Ouedraogo et al., 2001). Tng cng hm lng cht hu c trong t cn ci thin cht lng t v mt ha l v sinh hc t nh gip tng kh nng m ca t, kh nng hp ph v trao i cation, ci thin cu trc t, tng kh nng gi nc trong t v tng hiu qu s dng phn khong v c trong t. Cht hu c c tc dng lin kt cc cu th trong t to thnh khi n nh hn ch s ng vng trn b mt t, gia tng tnh thm nc. V mt sinh hc t, t c lng cht hu c cao gip tng mt s v hot ng ca ng vt t, lin quan n s khong ha cht hu c cung cp dinh dng ng thi ci thin cu trc t (Bossuyt et al., 2001). S hin din ca cc vi t khng c hnh thnh do ng vt t hoc do r ca cy trng v trc gp phn tng s ti xp t.

V th mc tiu lc kho nhm tm ra cc nghin cu v nh hng ca cht hu c n vic ci thin cc c tnh vt l t v nh hng ca cht hu c n nng sut cy trng. T gip tng hiu qu v bn vng hn trong canh tc nng nghip.1. TNG QUAN V PHN HU C1.1. Khi nim v cht hu c trong t Phn hu c l loi phn c sn xut t cc vt liu hu c nh cc d tha thc vt, rm r; phn sc vt, phn chung; phn rc v phn xanh. Mc d, nn cng nghip ha hc trn th gii ngy cng pht trin, phn hu c vn l ngun phn qu, khng nhng lm tng nng sut cy trng m cn c kh nng lm tng hiu lc ca phn ha hc, ci to v nng cao ph ca t (Ng Ngc Hng v ctv., 2004).Phn hu c c nh gi ch yu da vo hm lng cht hu c (%) hoc cht mn c trong phn. Cht hu c l mt c trng phn bit t vi m v mt ngun nguyn liu to nn ph ca t. Cht hu c l phn qu gi nht ca t, n khng ch l kho dinh dng cho cy trng m cn iu tit cc tnh cht ca t v nh hng n sc sn xut ca t (Nguyn Th ng, Nguyn Th Hng, 1999). C th chia cht hu c ca t lm 2 phn: Nhng tn tch hu c cha b phn hy (r, thn, l cy, xc ng vt) vn gi nguyn hnh th. Nhng cht hu c c phn hy. Phn hu c ny sau chia thnh 2 nhm: Nhm hu c ngoi mn gm nhng hp cht c cu to n gin hn nh: protid, glucid, lipid, lignin, tannin, sp, nha, ester, ru, acid hu c, aldehyde...chim mt t l thp (3-8%) (hnh 1) cht hu c c phn gii nhng c vai tr rt quan trng vi t v cy trng.

Nhm cc hp cht mn bao gm cc hp cht hu c cao phn t, c cu to phc tp c hnh thnh do hot ng tng hp ca vi sinh vt t, nhm ny chim t l cao (10-30%) trong cht hu c c phn gii.

Hnh 1: S phn hy xc b hu c sau mt nm c vi vo t. Hn 2/3 ca cht ny b oxid ha thnh CO2 v t hn 1/3 cn li trong t m phn ln l cht mn (Theo Brady and Weil, 2001. Trch t: Ng Ngc Hng, 2009).

1.2. Ngun gc cht hu c trong tNgun gc nguyn thy ca cht hu c trong t l m thc vt: thn, r, l cy sau khi cht i s b mc nt, hoa mu sau khi thu hoch th phn cn li nh: L hay r cng b phn hy cung cp cht hu c cho t. Ngoi ra ng vt cng l ngun cung cp cht hu c cho t. Cht hu c c b sung vo t t cc ngun sau y:

Xc sinh vt (cn gi l tn tch sinh vt): y l ngun hu c ch yu. Sinh vt ly thc n t t to nn c th chng v khi cht i li nhng tn tch hu c cho t. Trong xc sinh vt c n 4/5 l t thc vt. Tnh trung bnh hng nm t c b sung t thc vt 5-18 tn thn, r v l trn ha (Nguyn Th ng, 1999). Ngoi thc vt th xc vi sinh vt v ng vt t cung cp cht hu c mt phn ht sc ng k, mc d khi lng khng ln nhng c cht lng tt. Phn hu c i vi t ang canh tc th lng cht hu c do con ngi bn vo t l ngun hu c ng k. Nhng ni thm canh cao ngi ta c th bn ti 80 tn hu c trn ha. Ngun phn hu c bao gm: phn chung, phn xanh, phn rm rc, bn ao, ty thuc vo loi phn hu c khc nhau m cht lng khc nhau (Ng Ngc Hng, 2004).

Phn hu c l loi phn bn c loi ngi s dng u tin, t gn 3000 nm trc y Trung Quc (Nguyn ng Ngha, 2002).

1.3. S chuyn ha cht hu c trong tS bin i v chuyn ha cc xc hu c trong t l mt qu trnh phc tp, c thc hin vi s tham gia trc tip ca vi sinh vt t v ca ng vt, oxy khng kh v nc. Xc hu c trong t chu s tc ng ca hai qu trnh l qu trnh khong ha cht hu c v qu trnh mn ha cht hu c song song tn ti (hnh 2), ty thuc iu kin ngoi cnh, h vi sinh vt v loi xc hu c v t l C/N m qu trnh ny hay qu trnh kia chim u th (Nguyn Th ng v ctv, 1999).

Hnh 2: Tin trnh khong ha v mn ha lun xy ra ng thi trong t (Theo Ng Ngc Hng, 2009).

Khong ho l qu trnh phn hu cc hp cht hu c lin tc to thnh cc hp cht khong n gin, sn phm cui cng l nhng hp cht tan v cht kh c s tham gia ca vi sinh vt (Nguyn Th ng, 1999). N s tr li cho t cc cht dinh dng c t cho cy trng di dng cc cht v c.

Theo Nguyn Th ng (1999), th s khong ho ph thuc vo : thnh phn cht hu c, m ca t (thch hp l 70-80%), nhit (thch hp l 25-35oC), pH t (thch hp 6.5-7.5), v cng thong kh khong ho cng nhanh. Qu trnh khong ho xy ra nhanh khi gp iu kin thun li to ra nhiu cht dinh dng cho cy trng. Tuy nhin khong ho xy ra trong iu kin ym kh th s sinh ra nhiu cht c c hi cho cy trng nh: CH4, CO2, H2S(L Huy B, 2000). 2. TNG QUAN GIA PHN HU C V L HC T

2.1. Cu trc t v bn on lpCu trc t l s sp xp thnh mt dng c nh ca cc cp ht trong t. trng thi kt hp t nhin gi l n v cu trc t (ped), trng hp mt khi t kt dnh nhau do t bi v ra do cc lc khc nhau do nhn to (v d nh trng trt, ch p/nn cht, v thu li th gi l cc t (clod). Krull, Skjemstad et al. 2004()

Mt trong nhng vai tr quan trng ca cht hu c l hnh thnh cu trc v duy tr bn cu trc t hnh 3 (Cochrane v Aylmore, 1994). Hp cht mn l yu t chnh quyt nh nn ph ca t. Mn c tc dng kt dnh cc ht t vi nhau to nn kt cu t. Mn lm tng kh nng gi nc, gi cc cht dinh dng ca t, iu ha ch nhit v khng kh ca t. T to iu kin cho vi sinh vt t pht trin v hot ng hu ch cho cy trng v t (Mai Vn Quyn v ctv, 2005). Nu t giu cht hu c ngi ta c th trng trt tt c ni t c thnh phn c gii qu nng hoc qu nh (Trn Vn Chnh, 2006).

Cht hu c trc tip lm mt cng ca t nh vo tc dng gn kt cc ht keo nh li vi nhau, to nn cu trc bn vng, lm ci thin xp ca t (Ng Ngc Hng v ctv, 2004). Cht hu c lm gim tnh dnh v tnh do ca t gip qu trnh lm t c d dng hn (Nguyn M Hoa, 1999).

Hnh 3: Minh ha cht hu c gp phn ci thin cu trc t (Ngun: Sustainable Soil Management)

Mi tng quan gia SOC v cu trc t v tnh cht vt l khc c nghin cu, v nh gi xut sc c th c tm thy trong Tisdall v Oades (1982), Oades (1984), v Carter v Stewart (1996). N khng ch cung cht hu c cho t m cn lm gim t trng t (bulkdensity) v tng kh nng gi nc, m cn tng hiu qu cho bn on lp ca t. Angers v Carter (1996) cho rng, s lng tp hp nc n nh (WSA) thng c kt hp vi hm lng SOC, v carbon c bit khng n nh thng lin quan tch cc n s n nh tp hp t. Kay v Angers (1999) bo co rng ti thiu 2% SOC l cn thit duy tr n nh cu trc v quan st thy rng nu hm lng SOC t 1,2-1,5%, th bn on lp s gim nhanh chng. Boix-Fayos et al. (2003) cho thy SOC phi t c ngng 3-3,5% t c s gia tng bn on lp ca tp hp t.

Chaney v Swift (1984) iu tra bn on lp ca 26 t t cc khu vc nng nghip v tm thy mt mi tng quan tuyn tnh quan trng cao gia bn on lp v hm lng cht hu c

Hnh 4: Mi quan h gia bn on lp v hm lng cht hu c trong 26 t (v li t Chaney v Swift, 1984).

Martens v Frankenberger (1992) cho rng khi ti mn th cho Alfisol vi ba ln bn bao gm phn gia cm, bn thi, rm la mch v c linh lng. So vi i chng, cht hu c lm tng t l h hp t (139-290%), bn on lp (22-59%), SOC (13-84%), hm lng polysaccharide (25-41%), m ca t (3-25%) v gim dung trng (7-11%). Trong khi bn nc thi v phn gia cm dn n SOC cao hn, rm la mch ci thin bn on lp hn so vi cc nghim thc khc (tng 59% so vi 23% cho bn v phn gia cm) v c nh hng ln nht trn tng s polysaccharide, t l xm nhp v t l h hp. Nhiu phn tch hi quy tuyn tnh ch ra rng kch thch hot ng ca vi sinh vt dn n tng bn on lp, trong c th hin bi s hin din ca glucose v mannose sau ln bn u tin. Sau ln th hai, bn on lp tng quan vi polysaccharides (galactose v glucose) nhng khng tm thy c mi tng quan ng k sau ln th ba. iu ny cho thy ban u polysaccharides gp phn vo s n nh ca ht t nhng thnh phn hu c (humic) nh hng n s n nh lu di ca cc ht t. iu th v l ngay c nhng l khng ti (trong trng thi b hoang) tng trong tp hp, m c th l do lch trnh ti hng tun v cc nh hng tch cc ca chu k lm t v kh (Hnh 5).

Hnh 5: nh hng ca thay i cht hu c trn s n nh bn on lp t. Cc mi tn ch b sung hu c (sa i t Martens v Frankenberger, nm 1992).Hm lng cht hu c v bn cu trc lin quan cht ch vi nhau. S suy gim cht hu c trong t a n s gim xp v tng dung trng t (Tisdall Oades, 1982). Kt qu phn tch mi tng quan gia tnh bn cu trc v hm lng cht hu c tng bn di c trnh by trong hnh 6. (Trn Thng Tho. 2011).

Hnh 6: th biu din mi tng quan gia tnh bn cu trc v hm lng cht hu c tng bn di (10 20cm).

Kt qu cho thy tnh bn cu trc v hm lng cht hu c c s tng quan cht ch vi nhau c th hin qua mi tng quan thun vi phng trnh tng quan Y = 18.722x + 67.412, R = 0.7. Mi tng quan ny cho thy khi hm lng cht hu c trong t cng cao th tnh bn cu trc t cng tng. Nguyn nhn c gii thch l do cht hu c ng vai tr nh l cu ni cc phn t ca ht t li, l tc nhn gn kt cc ht t vi nhau, u ny ph hp vi nhiu nghin cu trc y, a ra kt lun rng ch s bn t c ci thin khi t c bn phn hu c.2.2. Dung trng

Dung trng l mt trong nhng ch tiu quan trng nh gi kh nng pht Trin h thng r cy trng v mc thong kh ca t.

Dung trng nh hng ng k bi cc th nghim (hnh 7), dung trng thay i t l da vo hm lng cht hu c cung cp vo t: thp nht trong cc l ng c v cao nht l i chng (Hnh 7). Trong s cc l nhn u vo, dung trng cao nht trong th nghim phn bn ha hc so vi th nghim bn phn hu c. H s xc nh (r2) dung trng t v SOC l 0,86 trong ng c, 0.86 trong nghim thc bt c + la m, 0,85 trong nghim thc rm la m, 0.87 trong bt c, 0.92 trong thi nghim phn bn, v 0,95 trong i chng (I Celik et al., 2004).

Hnh 7. nh hng ca phn bn ln hm lng cht hu c, dung trng kh v thm bo ha su 0-15 cm (a) v 15-30 cm (b) ca t a Trung Hi bn kh hn. CO: nghim thc i chng, F: phn bn v c (N-P-K), C25: phn hu c, M25: phn chung, C10 + MZ: phn hu c + mycorrhizae. Cc nghim thc trong cng su c cng k t th c ngha thng k khc nhau khng ng k (P 0,05) (I Celik et al., 2004).

Theo nghin cu ca Trn Nguyn Thanh Tm (2007), nu tip tc bn nhiu phn v c m khng b sung phn hu c vo t th lu di s c nguy c lm t b nn d, hn ch s pht trin ca h thng r cy trng do hm lng st trong phn v c lm kn dn cc t khng t. Vic bn phn hu c c tc dng lm tng cht hu c trong t v s hot ng ca h vi sinh vt t lm cho t tr nn c cu trc tt hn, thng thong hn. Chnh v vy lm cho dung trng ca t c xu hng gim hn so vi bn phn v c.

Bng 1: nh hng phn hu c n dung trng t(g/cm3) (Trn Sn Tng, 2011)

NT1: bn phn v c 150 60 60 + 1 tn phn hu c vi sinh; NT2: bn phn v c 120 60 90; NT3: bn phn v c 150 60 60 + 5 tn phn b phi kh (Trichoderma); NT4: bn phn v c 150 60 60 + 5 tn phn b bn ma (Trichoderma); NT5: bn phn v c 160 115 60 + 5 tn phn b phi kh.

2.3. Kh nng gi ncMt ch tiu quan trng ca vt l nh hng n ph nhiu ca t l kh nng ca t lu tr v cung cp nc v khng kh cho s pht trin ca thc vt. Kh nng ca t gi nc c gi l kh nng gi nc (waterholdingcapacity).Kh nng gi nc ca t c kim sot ch yu bi s lng, kch thc t khng ca t, v din tch b mt c th ca t. iu ny c ngha l vi mc tng cacbon hu c trong t ng ngha l gim t trng v c xu hng tng s lng cc kch c cc t khng. Cht hu c nh hng n tun hon nc trong t lm cho nc ngm su trong t c thun li hn, kh nng gi nc cao hn, vic bc hi mt t t i nh vy m tit kim c nc ti, ngoi ra cht hu c c tc dng lm cho t thng thong trnh s ng vng v trnh xi mn (Ng Ngc Hng v ctv, 2004). Mi quan h ny lm ni bt s kt ni lin thng gia cc cu trc t, t trng v kh nng gi nc.

Theo de Jong (1983) v Haynes v Naidu (1998) th s gia tng hm lng nc c lin quan n s gia tng hm lng SOC. Wolf v Snyder (2003) cho rng tng 1% SOM c th b sung thm 1,5% m bng khi lng FC. Emerson v McGary (2003) ch ra rng b sung mi gam carbon 10 kPa, s gia tng 50% hm lng nc s t c (Hnh 8). H cho rng carbon hu c c t dch tit t ectotrophic mycrorhiza s lin kt phn t t li vi nhau, trong s dn n mt s thay i kch thc ca cc t khng v kh nng gi nc 10 kPa.

Hnh 8: S gia tng % C trong kh nng gi nc mc 10 kPa ca tp hp bt (Emerson v McGary, 2003)nh hng ca kt cu trn hm lng nc trong t v SOC c nghin cu bi Bauer v Black (1992). H so snh t c kt cu th v mn t hai h thng qun l t trng trt (thng thng gieo trng v lp ph rm r) v hai h thng ng c (chn th v t b hoang). Tng t nh Rawls v cng s (2003) d on, h thy rng nhng thay i ln nht trong SWR c quan st thy trong t ct, ni s thay i chim 75% ca s thay i nng nc theo trng lng (PW) c hai FC v PWP . Mt s thay i n v trong hm lng SOC trong t ct gy ra mt s thay i ln trong PW FC hn PWP, nhng trong kt cu t trung bnh v mn, s thay i trong PW FC l song song vi s thay i PWP (Hnh 9).

Hnh 9: Nng nc ngoi thc a (FC) v im ho c nh (PWP) lin quan n nng carbon hu c trong ba nhm kt cu t (n = 256) (Bauer v Black, 1992).Trong t kt cu trung bnh, thc cht khng thay i trong FC v PWP khi SOC l 0,05) so vi nghim thc i chng (Hnh 6). Nm r + phn hiu qu hn trong vic ci thin cc tnh cht ca t vt l hn so vi phn v c.Ngun phn bn hu c c chng minh l c tc dng tch cc i vi tnh cht ca t vt l.

Hnh 14. nh hng ca phn bn ln xp su 0-15 cm (a) v 15-30 cm (b) ca t a Trung Hi bn kh hn. CO: nghim thc i chng, F: phn bn v c (N-P-K), C25: phn hu c, M25: phn chung, C10 + MZ: phn hu c + mycorrhizae. Cc nghim thc trong cng su c cng k t th c ngha thng k khc nhau khng ng k (P 0,05) (I Celik et al., 2004).

3. MT S NGHIN CU V HIU QU CA VIC S DNG PHN HU C LN MT S CY TRNG3.1. Tc dng cung cp cht dinh dng cho cy trng

Phn hu c cung cp cht dinh dng cho cy nh cht acid humic (Hong Minh Chu , 1998). Theo Nguyn Bo V, 1996 cc cht hu c cng l ngun dinh dng cung cp cho cy do mn b phn hy (Akio Inoko, 1984) v ha tan cc cht v c trong t.

Cht hu c khng ch l ngun cung cp cht dinh dng cho cy trng m cn c tnh cht bn vng n tim nng, nng sut cao nht cho php ca t nh con ng khong ha v ci to tinh cht l ha t (Wolfgangn Flaig, 1984).

V theo Nguyn Ln Dng (1968) ngun m b sung cho t ch yu da vo ngun phn hu c v s c nh m ca cc vi sinh vt sng trong t. Ngoi ra, bn thn phn hu c c cha cc nguyn t N, P, K, Ca, Mg v nhiu nguyn t vi lng cn thit cho cy trng (Trn Thnh Lp, 1998 ).Bng 2: Hm lng NPK c trong cc loi phn hu c t nhin (tnh theo % cht kh), (T Thu Cc, 1996).Loi phnNP2O5K2O

1. Phn chung

Phn ln0,45 0,600,410,26 0,55

Phn trn b0,29 0, 550,17 0,350,8 1,0

Phn g1,15 1,630,54 1,40,85 2,4

2. Phn c4 103 90,3 1,5

3. Kh du

Kh du lc7 7,21,5 1,61,3 1,4

Kh du bng4 6,52 31,5 2

4. Phn xanh

Mung l trn2,7 30,4 0,71 1,3

in thanh2,60,281,7

Bo hoa du4,7 50,6 11,5

5. Than bn

Ty Ninh0,380,030,37

C Chi0,090,150,31

Mc Ha0,16 0,910,150,31

U Minh0,250,07 0,10,25 0,30

3.2. Hiu qu ca phn hu c trn trng lng tiu kh

Bn phn hu c vi sinh 4 kg/gc kt hp phn v c cn i, bn gim lng phn ln v tng kali so vi bn theo nng dn, gip tng nng sut ht tiu c ngha. Tuy nhin, trong mt v cha gip ci thin c ngha i vi mt s c tnh ha hc t nh pH, hm lng cht hu c trong t, ch gip tng cation K+, Ca2+trao i v bo ha base trong t. Do phn hu c c hiu qu chm trong ci thin tnh cht ha hc t nn cn th nghim trong thi gian di hn ( V Th Gng v ctv, 2013).

Hnh 15. Hiu qu ca cc liu lng bn phn v c v phn hu c trn trng lng tiu kh (V Th Gng v ctv, 2013)

Kt qu nng sut tiu c so snh gia nghim thc i chng c bn phn theo nng dn ti im th nghim (125g N 195g P2O5 40 g K2O+2 kg phn b/gc) vi cc nghim thc bn phn v c cn i v c bn phn hu c. Kt qu trnh by Hnh 2.4 cho thy bn phn v c theo khuyn co (120 gN60 g P2O5 100g K2O/gc) kt hp vi 4 kg phn hu c vi sinh c b sung nm Trichoderma t trng lng tiu kh m 12% cao nht (3,5 kg/gc), cao khc bit c ngha thng k so vi s dng phn bn theonng dn (3,0 kg/gc) hoc ch bn v c theo lng khuyn co (3,1 kg /gc).Trong th nghim ny, trng lng tiu t cao hn so vi th nghim trc y ca Dng Minh Vin v ctv. (2011) ch t 2,2 kg/gc. Theo khuyn co ca nghin cu trc y th lng phn v c bn cho tiu t nng sut tt l rt ln 180250g N, 150 250g P2O5v khang 300g K2O. Tuy nhin, nng sut t c kh thp, ch khong 3 t/ha (Thangaselvabal et al., 2008). Vi mt trng tiu ti Ph Quc bin ng trong khong 2.200-2.400 gc/ha, bnh qun 2.200 gc/ha th nng sut tiu kh trn mi ha cc lng t kh cao, cao nht t 6,4 t/ha. Nng sut tiu canghim thc bn theo nngdn thp hn so vi nng sut cc nghim thc c bn b sung phn hu c c th ldo bn phn hu c ci thin c tnh vt l t v cung cp b sung cc khong vi lng cho cy tiu. Kt qu phn tch t cho thy t rt ngho K (0,12 cmol/kg) nn nh hng n qu trnh to ht ca cy tiu. Mt khc, bn phn hu c theo tp qun ca nng dn l trn phn b kh vi t, v th vi lng bn 2 kg phn hu c nhng thc tcung cp cht hu c vo t rt t. Do , cung cp thiu cn i dinh dng v hm lng cht hu c trong t thp hn chnng sut cy tiu. Thc t phng vn nng dn trng tiu cho thy cc vn t bn phnhu c c nng sut tri thp hn so vi cc hnng dn c bn phn hu c. Theo kt quca Hunh Vn nh (2010), nng sut tiu trung bnh ca cc vn t bn phn hu c l 0,84 kg tiu kh / gc v nng sut tiu trung bnh ca cc vn c bnphn hu c thng xuyn l 1,86 kg tiu kh/gc. Kt qu t c t th nghim ny qua mt v cho thyhiu qu r ca phn hu c c hoai, c cha nm Trichoderma gip nng cao nng sut tri tiu.Kt qu ny ph hp vi cc kt qu nghin cu ca Dng Minh Vin v ctv (2011) l phn hu c gip tng nng sut tiu trn t bc mu ti Ph Quc. Trn cc loi cy trng khc nh rau mu, la, cy n tri l bn phn hu c kt hp phn v c cn i gip ci thin nng sut cy trng c ngha (Thangaselvabal et al., 2008; V ThGng v tv., 2010; Dng Minh Vin v ctv, 2011).3.3. Hiu qu ca phn hu c b bn ma v Tithonia trong ci thin nng sut rau hng cy

Kt qu trnh by hnh 6.19 cho thy nng sut rau hng cy thu hoch t 1 ca nghim thc bn 10 tn BBM-Trico v nghim thc bn phn v c theo khuyn co t cao nht 19,91 tn/ha khc bit so vi nghim thc bn phn v c theo nng dn. Kt qu ny c th do vic bn phn khng cn i ca nghim thc bn phn v c theo nng dn khng c bn kali lm gim nng sut rau hng cy.

Nng sut rau hng cy thu hoch t hai cho thy nng sut rau hng cy ca nghim thc bn phn v c theo khuyn co v nghim thc 10 tn BBM-Trico t cao nht khong 16 tn/ha khc bit c ngha thng k so vi nghim thc bn phn v c theo nng dn v nghim thc 5 tn BBM-Trico. Kt qu ny cho thy, hiu qu lu tn v 2 khi bn 10 tn BBM-Trico lm tng nng sut so vi bn 5 tn BBM-Trico.

Hnh16: Nng sut rau hng cy trong hai ln thu hoch (Nguyn Vn Nht, 2008).3.4. Hiu qu ca phn hu c - Vi sinh trn nng sut v cht lng rau xanh trng trn t ph sa ti tnh Long An (Theo TC Khoa hc 2011:18b, Trng HCT)

Nghin cu do cc tc gi Cao Ngc ip, Trn Th Giang (Vin Cng ngh & Pht trin CNSH - Trng HCT) v Nguyn Thanh Tng, Nguyn Vn Anh (Trung tm Khuyn nng tnh Long An) thc hin nhm nh gi phn hu c-vi sinh (HCVS) t s phn hy xc b thc vt ca nm Trichoderma sp. kt hp vi hai chng vi khun c ch bn cho rau xanh vi 50% lng phn ha hc trn nng sut v cht lng (thng qua hm lng nitrat trong rau).

Kt qu nghin cu cho thy, bn 15 n 30 tn phn HCVS/ha v 50N-24 P2O5-12 K2O kg/ha cho rau n l c nng sut tng ng vi bn 100N-48 P2O5- 24 K2O kg/ha nhng hm lng nitrat thp. i vi rau gia v, bn 15 n 30 tn phn HCVS/ha v 50 N-42,5 P2O5-20 K2O kg/ha cho nng sut tng ng vi bn 100 N-85P2O5-40 K2O kg/ha; bn 15 n 30 tn phn HCVS/ha 80N-47 P2O5- 20 K2O kg/ha cho nng sut tng ng vi bn 160N -94 P2O5-40 K2O kg/ha cho hnh l; nhng hm lng nitrat thp. Tuy nhin, bn 30 tn phn HCVS/ha -99N-69 P2O5-55K2O kg/ha cho kh qua, da leo, u bp u ci thin nng sut v cht lng. Hch ton kinh t cho thy bn phn HCVS kt hp vi lng phn ha hc cho rau mung (v 1) v mng ti v ci xanh (v 2) c hiu qu nht; rau gia v v kh qua u thu li cao nht trong c 2 v. Tuy nhin, hiu qu cao nht v 2 vi da leo v u bp. Nh vy, bn phn HCVS cho rau xanh khng nhng tit kim lng phn ha hc m cn m bo cht lng sn phm.3.5. Hiu qu ca phn hu c b bn ma v Tithonia trong ci thin nng sut cam

Kt qu nghin cu cho thy bn phn hu c b bn ma gip tng nng sut cam c ngha so vi i chng v v c khuyn co. Nng sut ca l bn phn xanh D Qu cao c ngha so vi i chng nhng khng khc bit vi nghim thc v c khuyn co. Nng sut tri t c th hin qua bnh qun trng lng tri, tng s tri v tng trng lng tri. Phn hu c b bn ma v phn xanh D Qu gip tng trng lng tri v so tri fren cy c ngha so vi i chng (Hnh 17) . Kt qu ny ph hp vi nghin cu ca Dng Minh Vin v V Th Gng (2007) bn 10t.ha-1 phn hu c b bn ma kt hp v c cn i gip tng trng lng tri bi da xanh so vi i chng v v c khuyn co.

Hnh 17: nh hng ca cc nghim thc phn bn n nng sut tri trn vn cam (V Th Gng v ctv, 2010)Ghi ch: 1: i chng, bn phn v c theo nng dn (628g N 327g P2O5 - 64g K2O/cy)

2: Bn phn v c theo khuyn co ca trng i Hc Cn Th (250g N - 200g P2O5 -l20gK2O/cy).

3: Bn 10t.ha-1 phn hu c b bn ma c cha nm Trichoderma + phn v c (theo khuyn co).

4: Bn 20t.h-1 cy phn xanh Tithonia (D Qu) ti + phn v c (theo khuyn co).

KT LUNCi thin tnh cht vt l t gp phn quan trng trong ci thin iu kin gip b r cy trng pht trin thun li.

Tnh cht vt l t ti ho gip s vn chuyn nc, dng cht, kh nng thm v thot nc tt l yu t cn thit trong cung cp dinh dng, cc phn ng ha hc, s pht trin v hot ng ca vi sinh vt v ng vt trong t.

Cung cp cht dinh dng v nng lng: cung cp CO2 cho s quang tng hp cht hu c. Cung cp cht dinh dng khong, c bit l cht m, ln, lu hunh v cc nguyn t khc, bao gm c nguyn t a vi lng.Vic bn phn hu c gip t ti xp, gim s nn d, gip duy tr c cu trc tt, thun li cho s pht trin ca r cy trng v trnh s ng vng trn b mt t.

Vic bn phn hu c em li hiu qu kinh t cao, tn dng ngun thc vt sn c trong t nhin phn hu c, gip ci thin mi trng v nng sut cy trng.

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y = 18.722x + 67.412

R

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Tnh bn cu trc (SQ)