BIỆN PHÁP CẢI THIỆN ĐỘ PHÌ NHIÊU ĐẤT VÀ NĂNG SUẤT LÚA TRÊN ĐẤT PHÙ SA CỔ THÂM CANH LÚA TẠI HUYỆN MỘC HÓA – TỈNH LONG AN docx

T Phn p, Thy s Sinh hc: 26 (2013): 43-49 43 BII THI   I HUYN M TNH LONG AN Tr 1   1 n 1  1 1 B p c ng dngi hc C Thông tin chung:  08/11/2012 20/06/2013 Title: Improvement of soil fertility and rice yield on old alluvial soil at Moc Hoa district, Long An province Từ khóa:     Keywords: Old alluvial soil, compost amendment, rice-cash crop alternation, soil nutrients ABSTRACT In the Mekong delta, old alluvial soil types are poor in soil nutrients. Famers have applied only inorganic fertilizers for double rice cultivation and have not paid much attention on using organic manure. With high dose of inorganic N and P applied, intensive rice cultivation has led to soil degradation and low rice yield. Objectives of this study were to find the way to improve soil fertility and rice yield of mono-rice system on old alluvial soil in Moc Hoa district, Long An province. Treatments were arranged in randomized complete block design with 1) Double rice crops            Rice alternated with sesame;4) Rice alternated with peanut; 5) Rice alternated with soybean. Experiment was conducted for 8 years. Results showed that the system of rice crop alternated with cash crop led to increase significantly soil available nitrogen, labile carbon content and nitrogen mineralization in comparison with traditional rice cropping practice. Organic amendment result the increases of labile carbon and available nitrogen in soil compared to the rice treatment without compost addition. As consequence, the rice yield has been improved by either compost amendment or alternative cropping of rice and upland crops.            h sinh                   T Phn p, Thy s Sinh hc: 26 (2013): 43-49 44 1 M U Nhiu v     u qu  ng nhu c   th gii (Olk  ., 2002). Hin ti,   th    c chim hai n ba v i ding 14 triu ha  n c   n l     o ca  u (Cassman  , 1995; Mahieu  ctv. suy git n nay trong nhi n t t ra s nghi ng v  n vng ca h th  (Cassman  , 1997; Olk  , 1996). Mt s  hin       d     thuc bo v thc v  Vi vi       c nu ng bi        n vng ca sn xu     n ph  u bi   ci thin  ph nhiu t, ci thi  su        chn la bi   p v u kin            sn phm. u kin ngc ca h th  c, s   ym   a thc v  hn ch kh    m t     a cht h m (N) hu dng b kim gi i dng to p cht hy           t ruma, 1976; Dobermann       t hu    b     u t  sinh hc t   p cht h   y  t ng       ng kh c do  u v ng cht h  th gim dn gim kh m hu dng (Stevanson et alng thi s    vi sinh v     gim mt s vi sinh vt. T  sung gim, hiu qu kinh t mang l  c thc hin nhm ci thi          n xu         theo ng sn xun vng. 2 N CU m          (Plinthosols    ng 4,7 thuc lot chua vng cht hu       i cation (CEC) th   m tng s  i rt thp. Dung trng tng m        ng b   ng Fe 2 O 3 t   Al 3+    t cao (Bng 1). Nhng                 ng bi  i thi         t ng. Bng 1: Mt s ch c cm Ch   pH H2O 4,7 CEC (meq/100g) 3,75 Cht h 2,18 N tng s (%) 0,154 K + (meq/100g) 0,08 Ca 2+ (meq/100g) 0,48 Mg 2+ (meq/100g) 0,60 Na + (meq/100g) 0,06 Dung trng (g/m 3 ) 1,32  xp (%) 43 Fe 2 O 3 (%) 2,84 Al 3+ (meq/100g) 2,53 Thnghim ng ruc thc hin di hn t      ti x Bnh Tn, huyn Mc Ha, tnh Long An, theo th thc khi hon ton ngu nhin gm nm nghim thc vbn ln lp li vi di m 2 cho m  m, gm cc m hnh nhsau: Nghim th   Nghim th       tn/ha   T Phn p, Thy s Sinh hc: 26 (2013): 43-49 45 Nghim th        Nghim th      u ph Nghim th      u    c him, m t c ly theo nghim th  i v      i nhiu v   t   -   u, mang v   n m m hu dng, cht h   t, carbon d  . Kh    m         t c thu thi v    Cht h nh b Walkley- Black. Cacbon d      bm ammonium (N-NH 4 + m nitrate (N-NO 3 - ng m mt  nh bng  S li    c x  ng ng   m thc  m 3 KT QU O LUN 3.1 m (N) hu dt Kt qu   cho thm hu dt  m thc l ng t 21,2 -  th   i nghim th    t).  m th            t hiu u ki tri   ng N hu dng ng thi, nghim th          m hu d t qu  c gi hm hu dng t s  hp cht het al., 1999). m hu dt gi nghim thm 3.2 Kh m (N) 3.2.1 Hng N-NH 4 + Kh    -NH 4 +  u kin  c thu   y  thu  ng N-NH 4 + c  m th  -m thc     t qu  c gi    tim h -NH 4 + u din ra m  nghim th   -    nghim th  n   ng N-NH 4 + n  hai nghim thc m th      m thc   -   ng N-NH 4 +  ng gim. Sau tu ng N-NH 4 + git        m th  -u i nghim th t qu  ng cht hm         u ki    ng l   chuytrate. T Phn p, Thy s Sinh hc: 26 (2013): 43-49 46  N-NH 4 +   3.2.2 ng N-NO 3 -  ng N-NO 3 - c   th  tr   n    ho ng ca vi sinh v  u kin ng ln N-NH 4 + -NO 3 - ng N-NO 3 -           m th -   u phng so v  nghim th        u ki y s  n ca c ng vi sinh vt  - NO 3 -   3.3 ng cht ht Kt qu ng cht h   t bi ng t 2,14-2,8% ng cht hp  u  m   nghim th      ng cht h          mt th i m th t qu     nghim th     mi v thu hoc r i trong ng cht ht    m th     ng oxy        t hu  m th       h    ng cht h      c gi h        p chng nm Trichoderma  t. Chng n   din ra ti nghim th  0 10 20 30 40 50 60 0 tuần 2 tuần 4 tuần 8 tuần Thời gian ủ N-NH4+ (mg/kg đất) Lúa - Lúa Lúa+10 tấn HC - Lúa Lúa - Mè Lúa - Đậu Phộng Lúa - Đậu Nành 0 5 10 15 20 25 0 tuần 2 tuần 4 tuần 8 tuần Thời gian ủ N-NO3- (mg/kg đất) Lúa - Lúa Lúa+10 tấn HC - Lúa Lúa - Mè Lúa - Đậu Phộng Lúa - Đậu Nành T Phn p, Thy s Sinh hc: 26 (2013): 43-49 47   3.4 Cacbon d y Kt qu    ng cacbon d  y mc m th ng cht hm thc    m th                 ng cacbon d   ca nghim thi th thm thi. Kt qu  c gi     c g   trng , thiu oxy, hong ca vi sinh vt m kh  tha thc vt. Mt ngc c, cht hn din  ng hp ch  ng cacbon d  hu trong h th h so vi nghim th th c gi m  n cacbon d  h          ng h vi sinh vu kin t vi sinh vt ho ng cacbon d y.   T Phn p, Thy s Sinh hc: 26 (2013): 43-49 48 3.5  Kt qu  m cho th  t   m th        i nghim th   y cht ht thun l          vt hong cacbon d          m hu d   sut ca h th  so vt qu p vu ca Dobermann  (2000), tr t cao i tr t  nghim th  bi      i nghim thc  ng cht h u qu s d    m hu d  hong ca vi sinh vt.   4 KT LUN Kh    m hu dng, s ng cacbon d  ht  m th  m th           i nghim th h    U THAM KHO 1. 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