| Effect of multiple forage rape within after spring wheat on soil chem-physical properties, soil culturable microorganisms activities, soil enzymatic activities and correlation of soil nutrients factor, as well as rape growth properties were studied by the field experiment in tillaged-layer soil. Root exudation of rape were identified, and biological characteristics of rape were tested by water-culture and germinations. the main results showed:1. Root exudation of rape mainly include organic acid, hydrocarbon, benzene, alcohol, ester, ketone, amide, aldehyde, ether, thiazole and phenol et al. Dibutyl phthalate was finded in 26.71minute,and Corresponding content is the highest(22.55%), other compound is lower. root exudation of growth 20 days is more than 60 days in same phosphorous treatment, root exudation of no phosphorous treatments is less phosphorous treatments in same stage.Rape can exudate much organic compound(butylated hydroxytoluene) with stronger allelopathic effect in rape seedling stage, but rape root exudation sharply decreased in harvest stage.Rape of lack phosphorus intimidate also can exudation much stronger allelopathic that can promate the growing of horsebean seed, and can control growth of maize and rapeseed. Root exudation of rape can limit growth of radicle and promote growth of embryo for wheat, rape, horsebean and maize seed.2.Wheat stubble multiple forage rape reduced soil gravel content, improved soil clay granule quality, soil fertility and soil aggregate stability. multiple rape greatly altered ＞0.25mm water- stability aggregate, not affect for＜0.25mm aggregate. Soil aggregate(＞0.25mm) content of rape field reduced 3.82%(Lanzhou), 14.60%(Wuwei)than CK* in seedling stage and heightened 19.65%(Lanzhou) and 4.82%(Wuwei)in harvest stage, but still less than CK in the same stage.Total soil aggregates content apparently higher than CK*and CK in different treatments. soil microaggregates (＞0.25mm,0.005～0.01mm,0.001～0.005mm and ＜0.001mm) content decreased with the densities decreased.Compare with CK*, shabby of the aggregate(＜0.001mm) decreased 49.12%max and 68.35%max in the lanzhou and wuwei,(p＜0.01), Compare with CK in the Lanzhou and Wuwei, it was descended 51.92%max and 71.35%max in the rape seedling stage,(P＜0.05),and descended 28.69%max and 36.89%max in the harvest stage. Distract rate of clay(＜0.002mm) was positively significant reduced 24.43%max in Lanzhou, but no significant in Wuwei, the higher with densities and fertility, the lower with distract rate of clay(＜0.002mm). Aggregate degree (＞0.05mm) is positive significant in different rape density,(p＜0.01),but inregular in different fertility.3. After multiple rape,soil organic carbon increased 16.61%max(Lanzhou) and 12.75%max(Wuwei), but oxidize-stability rate of organic carbon decreased 34.58%max(Lanzhou) and 30.21%max(Wuwei), and F2(KOS) higher than other treatments, (P＜0.05), but inregular in different density.Multiple rape and spring wheat stubble increased soil organic matter,Lanzhou organic matter higher(average 14.74% )than Wuwei,the higher density and the lower fertility,the higher soil organic matter, (P＜0.05). Multiple rape apparently decreased soil total nitrogen and alkalihydrozable, and increased soil available nitrogen utilization efficiency,( P＜0.05). Compare to CK*, soil total phosphorus positively significant decreased, available Potassium(K) and available phosphorus(P) positively significant increased in rape seedling.Compare to harvest and seedling stage, total phosphorus and available phosphorus changed without apparent distinction,but available Potassium increased,and it gradually reduced with enhancement of debsity and fertility.After multiple rape,soil acidity-alkalinity(pH) and density-weight gradually abased, (p＜0.01). 4. After wheat harvested,soil catalase enzyme activities significantly improved with total seasonal growth stages of rape and density diminished. After multiple rape,soil cellulase enzyme activity significantly improved with density diminished and feitilit...
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