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Conservation tillage is an important international trend ofdevelopment of agricultural technologyThe protection cultivation is the most important international agricultural technology development tendency. The smashed straw technology is one essential technology of the mechanized protection cultivation. Using smashed straw machines can effectively solve the problems that striving for time and labour during the busying farming time, and can make the agricultural entire mechanization come to truth. It also can avoid environment pollution caused by straw setting on fire. According to multi-function and reducing production cost, multi-function smashed straw machine was developed. It not only can smash straw together with the stubble and put it back to the farmland to increase the nutrient once time but also can according to our practical necessity to choose rotary tilling single function. (1) On the basic of studying the elementary theory of smashing straw, the integral structure design plan of multi-function machine was introduced. The machine is mainly composed of hanging system, gearbox, belt transmission system, stalk-soil returning roller, rotary tiller roller, and depth limit roller. Power is transmitted from the tractor power output shaft to the gearbox. One shaft of the gearbox is accelerated by both bevel gears and strap transmission. And then it drives the stalk-smashing knives revolving quickly. Another shaft is moved by the bevel gears and strap wheel to drive the rotary tiller working. (2) The innovative point is the design of new gearbox, which has realized the composite work or single work of smashing straw, stubble and rotary tillage for the first time. It makes one machine has two uses. The gearbox is mainly composed of bevel gears, poking fork, clutch, and bearings. Using the separation or union between the clutch and gears, the separation or union of the power can be realized. So, the machine can choose smashed straw work or rotary tillage work. And the intension of bevel gears, belts, axes are checked. (3) The experiment of the machine is carried on the field. The results of the experiment can satisfy the agronomy request. The test result indicates that, the machine has good qualities to smash the straw and stubble. The average length of the smashed straw is 5.2 cm. The smashing qualified rate is 98%. The stubble smashed rate is 90%. The smashed straw is thrown equably. The fraction of coverage is high. The work performance is stable. When the machine chooses the single rotary tillage work, the rotary tillage depth can arrive at 16 cm. The crumble rate is 85.7%. After rotary tillage work, the farmland is smooth. It can satisfy the agronomy request and can carry on the following sowing seeds work directly.The crop straw is an important biologic resource in agricultural production system. Theapplication of the crop straw resource is involved with not only the soil fertility, water and soilconservation in the whole agricultural system, but also sustaining development problems such asthe environmental safety and the effective utilization of the regenerative resources. The straw returnin mechanical method is one of the effective ways to solve the straw processing. At the present time, the straw return machine has become of an important field in agriculturalmachinery study in China. However there are still lots of problems existed in the study of the strawreturn machine of whole rice stems. (such as power consumption is too much) In order to solve theimpact of those factors on the power consumption, such as structural parameters, operatingparameters and so on of each component in the machine, and reduce power consumption, thepaper implemented a design and experimental investigation on the parameters of the straw returnmachine. (1) The integrated design plan on test stand was put forward in this paper and throughmechanics analysis of the straw return machine, the structural parameters and operatingparameters which affected the operating quality of straw return machine are chose as the mainresearch factors. (2) The theoretical analysis and optimizing design were implemented to the structuralparameters of major working components, such as the clearance between cutter heads, thearrange of bent blade, grass removing angle and setting angle. (3) The sensor section has been chose, designed and processed logically, and then the testsystem was calibrated. (4) Among those influencing parameters, the paper chose the clearance between cutterheads, machine forward speed and knife roll revolving speed as experimental factors, whichhave a great influence on working status and power consumption (about the straw return machine),then put forward the experimental scheme and conducted experimental investigation as per the twotimes orthogonal rotational regressive test plan. (5) Through the analysis of data processing about the test date, a mathematical modelregarding the influence of the clearance between cutter heads, machine forward speed and rollrotational speed on the torque of the machine was achieved and the rule of impacts of these threefactors on the torque were analyzed as well. (6) Through the theory analysis about the model forenamed, another mathematical modelregarding the influence of the clearance between cutter heads, machine forward speed and rollrotational speed on the power consumption of the machine was achieved and the rule of impacts ofthese three factors on the power consumption were analyzed as well. Through the forementioned experiment and analysis, the optimal association schemes of theclearance between cutter head, machine forward speed and roll rotational speed on powerconsumption were given in the paper, on the premise that the operation requirements (such aspercentage of coverage, the tiling depth, and hack) were fulfilled. It provides the importanttheoretical foundation for further optimal design of parameters for whole machine.By comparison with routine fertilizer experiments, long—term fixedposition experiments that is an important means by which corn fieldecosystem are studied have many advantages. Experiment was carried outwith flouvo-aguic soils of Huang-Huai-Hai Plain coming from Huadian andJiaobin village of Qihe Shandong Province. Pot experiment, setting six maintreatments of straw combination to fertility and two subsidiary treatments ofsoil texture, were carried out to study the dynamic change of soil properties,translation of potassium form, nutrient balance, activity of soil enzymes andmicrobe species in the condition of wheat/maize rotation system. The effectand mechanism of increase production were also discussed preparatory. Theresult showed: 1 Soil salinity was positive related to the amount of using strawmarkedly, and improved highest by straw combination to fertility. Medium loamsoil was higher than sandy loam soil. In addition, soil salinity were effectedby climate、growing season et al. 2 Straw back to soil improved porosity, reduced soil unit weight and pH,harmonizd ecological condition and created favorable soil environment. 3 Soil organs matter and available nutrient were improved by strawback to soil, and they had the same seasonal dynamic change, highest inJune 2 and lowest in June 22. Soil organs matter and available nutrientdecreased with year, and medium loam soil was higher than sandy loamsoil. 4 Soil non-exchangeable K, water soluble K, specifically absorbed Kand non-specifically absorbed K are all positively related to the amount ofstraw remarkably, while mineral K is negatively correlative. The variant 3 regularity of soil K is that non-exchangeable K and specifically absorbed Kare increasing, but the other forms of K are decreasing. 5 Soil available Zn、Fe、Mn were all positive related to the amount ofusing straw markedly, but soil available Cu was unmarked. Soilmicroelement had the same rule, N1P1M3>N1P1M2>N1P1M1>M2>N1P1M0 > N0P0M0, and they all had evident seasonal change exceptavailable Cu. 6 Soil urease and phosphatase had the same trend, N1P1M3>N1P1M2>N1P1M1>N0P0M2>N1P1M2>N0P0M0, and they were related to the amountof using straw nearly and all positive related to soil organs matter andavailable nutrient markedly. Soil urease and phosphatase decreased withyear. 7 Straw returning increased the quantity of soil bacteria, fungi andactinomycetes, and bacteria>actinomycetes>fungi. The quantity of microbewas least in tillering stage and increased after reviving stage, and cornjointing stage and male tetrad stage were its fastigium. 8 Straw returning increased yield notably, and the effect of mediumloam soil was better. Yield、1000-grain weight、biomass of wheat and spikegrain weight、1000-grain weight of corn were all positive related to theamount of using straw markedly, but plant height、grains/ear、effective/earof wheat and grains/ear、rows per spike of corn were unmarked. 9 Amount of N, P and K absorption increased with the amount of usingstraw, and medium loam soil was higher. Applying the same chemicalfertilizer, soil N was surplus, but soil P and K were waney.Straw are a crucial source of nutrients in both natural and agricultural ecosystems. It is a very essential method for soil fertility, quality and healthy by amending straw to the soil. The microorganisms in soil play an important role during the process of the straw decomposition after the straw was amended to the soil. The object of our study was an investigation on microorganisms related with cellulose decomposition in straw-amended soil. There are three parts in this study. In the first part, the diversity of soil microbe cultured at different cellulose enrichment culturing conditions was analyzed by molecular technology of DGGE combined with statistical methods of clustering analysis and PCA. Both cluster dendrogram analysis and PCA analysis demonstrated that different cellulose enrichment culturing conditions might cause different effect to the soil microbe. The structure and components of the samples incubated in CMC medium and PCS medium at 50℃ showed a relatively high level of similarity, In contrast, those incubated in CMCmedium and J medium were significantly differentEmploying nylon net bags, carborundum tubers and plant straw/shoot sections, the decomposition rates and nutrient release patterns of straw returned to the field with different returning methods were studied. Soil fertility and crop yields in the field with straw treatments were examined. The allelopathic effect of rice straw on wheat germination was studied with indoors germination experiments in order to seek the solution to this allelopathic problem and offer practical techniques and gudence to farmers in rice straw mulching areas. The main results were achieved as below: 1. Wheat straw and rape shoot were decomposed much faster at the very beginning and slower at the later stages of the experiment. The wheat straw was easier to decompose than the rape shoot, giving a decomposing rate of 66.18% after 100 d for wheat straw against 55.62% for the rape straw. As for the nutrient release rates, it appeared that K was the fastest and followed by P and N from two types of straws. Within the first 10 d, amount of K released accounted for 98.92% for the wheat straw and 98.74 % for rape shoot, very close to its total content. The study further revealed that amount of K released accounted for 94.76% and 95.93 within 6 d. During the decayed process of wheat straw, the damage of straw tissues occurred predominately at thin parietal cells of fundamental tissue and its vascular bundle, epiderms and mechanical tissue had no evident damage.The fundamental tissue of wheat straw and its vascular bundle remained almost intact within first 50 d and decay was observed thereafter. During the decay process of rape shoot, the decomposition of organization structure started after 10 d. The vascular cambium, phloem fiber, parenchyma and epidermis above the secondary xylem, however, were started to decay and fall off within the first 10 d. 2. Employing nylon net bags and carborundum tubers, the decomposition rates and nutrient release patterns of rice straw in the field with different returning methods were studied. Results showed that rice straw decomposed much faster at the very beginning than at the later stages of the experiment. The straw decayed faster when it was buried into the soil, yielding a decomposition rate of 76.55% after 210 d against 53.50% for the surface mulching straw. Among the three nutrients, release of K from the straw was the fastest, followed by P and N, regardless of returning methods used. Within the first 10 d, amount of K released accounted for 50.32% for the surface mulching straw and 90.13% for the buried straw. When the straw was mixed into the soil, the major form of available N was nitrate (＞80%), with reminders of NH_4~+ and soluble organic nitrogen. Meanwhile, the phenomenon of soil microbes grabbing available N was observed during the first 40 d of straw decomposition and it disappeared thereafter, resulting in net N release from the soil with filtration. After N fertilizer was amended with buried straw, it offset the need of microbes for available N to decompose the buried straw. During the decayed process of rice straw, the damage of tissue structure started from thin parietal cell of fundamental tissue and its vascular bundle, while epiderms and mechanical tissue were not evidently damaged.In the early days of straw returning, the damage of tissue structure for the buried straw was more serious than the mulched. As decay proceeded, the changes in epiderms and mechanical tissue and its vascular bundle were not different btween the two different return methods, after the fundamental tissue of rice straw and its vascular bundle were decomposed. 3. Straw returned to the field enabled to reduce soil bulk density, increased soil porosity, improved soil structure, increased soil available nutrient and crop uptake and finally resulted in yield increases. Soil bulk density was reduced by 0.03g/cm~3 and soil porosity increased by 0.99% compared to the initial data of the experiment. The soil available phosphorus and potassium were increased, especially for potassium. Rice yield was increased by 5.61% with mulching wheat straw, and by 1.31% with mulching rape shoot. Wheat yield was increased by 6.16% and rape yield by 7.08% with mulching rice straw. 4. Allelopathic effect of water soaked rice straw extract on wheat germination was tested. Results showed that the extract significantly depressed germination and elongation of seedling and roots of wheat. It appeared that it showed a stimulating effect of the extract at lower concentrations (0.01 g/ml) and an inhibitory effect at higher concentrations (=0.02g/ml). The inhibition effect was more severe to seedling growth of wheat than its germination. With introduction of plant regulator gibberellin or humic acid to the extract, the inhibitory effect of the extract on wheat germination was relieved. As the concentration of the extract was greater than 0.04g/ml, a serious inhibitory effect was observed and this could not be reversed by addition of gibberellin or humic acid any more. 學 院 信息學院 專 業(yè)年 級 姓 名 指導教師 職 稱 英文科技翻譯