| Draught resistance of ploughs, the energy required for ploughing, the quality of ploughing, and expenses depend on the plough body design. This is determined by the share-mouldboard parameters and the parameters of its supporting surfaces. Draught, straw movement and soil resistance are very important parameters for evaluating the performance of tillage implements. This study investigated the performance of the trashboard mouldboard plough to optimize its use. A two-year field study was conducted to investigate the performance of a lightweight trashboard mouldboard plough (with and without trashboard). The minimum amount of straw is still needed to protect soil from wind and water erosion. Despite the large number of studies conducted, a better understanding of the relationships existing between soil movement, straw displacement, straw burial and soil and tool parameters has not been elucidated. This is likely attributable to the complexity of soil genesis, textures, un-unique weather conditions, and the cropping systems associated with each soil under study.This study consisted of laboratory and field experiments. The laboratory experiments were carried out in the Department of Agricultural Mechanization, College of Engineering,Nanjing Agricultural University (NJAU), while the field experiments were conducted at the Jiangpu Experimental Farm of Nanjing Agricultural University in Jiangsu Province, P. R.China. The variables in this study were, tillage depth, performance of trashboard mouldboard plough, draught and reaction forces with and without a trashboard under two levels of straw, wheat straw displacement, burial, and different soil moisture content, on a low speed of 0.1 m/s were measured. Simulation models of stress distributions were developed using finite element method (FEM) and compared with the stress distributions observed in the field with two levels of straw and plough with and without trashboard. The experiment was further extended two years to investigate the difference of using a trashboard under different soil moisture contents.One potential problem for the mouldboard plough is that the implements tend to cut both the residue and the soil by isolating, pulling and pushing them for lifting and translocating for burial. This may cause low efficiency of straw incorporation and poor traction performance. During ploughing, the presence of a trashboard cuts part of soil slice ahead of mouldboard, facilitating quick straw burial before soil slice turn-over. However,no data is available for a thorough understanding of the interactions among the soil, the tillage tool and the trashboard.The results of these experiments are summarized as follows:1. Draught requirements are an important parameter for tillage tool performances. This study investigated the influence of trashboard on the performance of mouldboard plough and the system optimization. Draught and vertical forces acting on the plough were measured with and without a trashboard under two straw conditions, i.e. with only stubbles and with dense straw cover (WTNS - with a trashboard under only stubbles, WTHS - with a trashboard under dense straw cover, WTONS - without a trashboard under only stubbles,WTOHS - without a trashboard under dense straw cover). Field soil moisture content was kept at about 30%. The study also used the finite element method (FEM) to simulate stress distribution on the plough. Results showed that draught significantly increased without a trashboard under dense straw cover as compared with only stubbles. For the mouldboard with and without trashboard attachment, different draught performances were found among the treatments. For 15 cm tillage depth, the combined effect of both trashboard attachment and straw condition on ploughing draught was found to be WTHS (2794.88 N)>WTNS(2345.69 N) and WTOHS (3248.87 N)>WTONS (2760.81 N). Vertical reacting force increased significantly with the depth of ploughing, but was independent of the straw level and trashboard attached. The trashboard attachment increased draught significantly. When using a trashboard and in stubble conditions, soil displacement ranged from 33 cm to 60 cm,the mean value of which was 48.89 cm. Soil displacement without trashboard attachment is from 50 cm to 70 cm, an average of 64.22 cm. Under dense straw cover conditions, soil displacement without trashboard attachment ranged from 38 cm to 57 cm, an average of 46.44 cm. However, this value with trashboard ranged from 45 cm to 60 cm, an average of 49.77 cm. Reduced soil displacement with the trashboard attachment was also found in other soil conditions, both in bare soil and with standing stubbles. FEM results were found to be compatible with the experiment. FEM results explained stress and deformation distribution on the mouldboard surface. The simulated maximum equivalent stress acting on the mouldboard plough was 279.43 MPa, while the material's yield stress was 250 MPa.Attaching the trashboard with the mouldboard plough is important where straw cover was dense.2. A minimum amount of straw is still needed to protect soil from wind and water erosion. To better understand the soil protection effect of straw, the relation of wheat straw displacement and its burial status with ploughing speed, tillage depth and the attachment of trashboard were studied. Three controlling factors were evaluated in a field tillage testing:two types of ploughs (with and without trashboard), three lengths of straw (100 mm, 150 mm, and 250 mm), and various straw conditions. Straw pieces with specific lengths were prepared before the experiments and used as point tracers to measure the soil and straw displacement. The results indicated that the soil and straw displacements were significantly different but that the two were interrelated. As the length of straw is increased, the 150-mm lateral and longitudinal lengths of straw exhibited lower movement than those of the 250-mm lengths of straw; the soil displacement decreased due to the forward and lateral displacement of the straw; the straw displacement was always significantly larger than soil displacement, independent of the straw mixtures. Attachment of a trashboard reduced the soil displacement, but had no apparent effect on the straw displacement. Longer straws were less effective to be incorporated into the soil than the shorter ones, and the presence of a trashboard led to higher straw burial performance. The results also indicated that low tillage speed resulted in larger soil fragments and straw displacement with more straw buried. The use of a WTONS produced 54% residue coverage, while the use of a plough with trashboard (WTNS) produced 42% residue coverage. The minimum values of residue coverage were found in the WTNS treatment compared to the WTONS treatment. A trashboard reduced significantly the percentage of residue coverage compared to the plough without trashboard. Moreover, longer straw was more effective on soil fragments than shorter straw at the same speed. However, straws neighboring the share were more extensively displaced than those nearby the plough body.3. During ploughing the presence of a trashboard cuts part of the soil slice ahead of mouldboard, facilitating quick straw burial before soil slice turns-over. Two-year field study was conducted to investigate the performance of a lightweight mouldboard plough with and without trashboard, as influenced by stubble height condition and soil water content. The performance of trashboard mouldboard plough for the optimization of their use, ploughing depth, 30% and 24% soil moisture content and reaction forces were measured for both years. Addition the movement residue, soil displacement, straw burial and soil colds size were measured on the speed of 0.1 m/s. The results showed that in the first year, when a trashboard was attached the field had higher draught and reaction force in both stubble and dense straw cover situation. This was also observed in the second year for only the stubble condition. Soil forces on the surface of a mouldboard plough with and without a trashboard at 24% average moisture content with a standard deviation of 1.2%, and different depths of operation and with two straw conditions it indicated that at the depth of 15 cm, soil forces were 1794.88 N with a trashboard under dense straw cover and 1248.87 N without a trashboard at the same height. 1345.69 N with trashboard only stubble of straw and 1060.81 N without a trashboard in the same condition respectively. It was observed that minimum force was applied on WTONS, while maximum force was applied on WTHS. Similar trends were observed at 5 cm and 10 cm operating depths, so using a trashboard at 24% soil water content increases soil force requirements. When comparing the use of a trashboard with two levels of water, it is suggested that it is better to use it at high water content. The statistical analyses of data were highly significant (p<0.01). The results indicated that the highest water content reduced draught force when the trashboard attached.4. Over 500 million tonnes of wheat straw are produced annually worldwide, the majority of which are burnt in the field causing significant environmental and health problems, serious traffic accidents as well as the loss of a valuable resource. However,every 1.3 kg of wheat grain produces about 1kg of straw. Wheat straw is abundantly available and renewable and can be used as an energy source in gasification and combustion systems. Proper understanding of the physical properties of wheat straw is necessary for utilizing these materials in thermochemical conversion processes. The physical properties (moisture content, particle size, bulk density and porosity) of the straws of Su Mail88 and Yang Fu Mai No2 were evaluated in this study. Also Surface Residue Cover was determined. The moisture contents of Su Mail 88 and Yang Fu Mai No2 were in the ranges of 18.26-32.36% and 15.54-28.08%, respectively. The average moisture content for Su Mai188 variety was significantly higher (p<0.05) than that of Yang Fu Mai No2 variety. The particle sizes of Su Mai188 and Yang Fu Mai No2 were in the ranges of 0.8-51.1 mm and 3.2-45.1 mm, respectively. All the Yang Fu Mai No2 varieties had a normal distribution of particle size around the main value of 3.2 mm while the particle size distribution for the Su Mai 188 showed a decreasing trend, the larger the particle size the higher was the weight percentage. The average bulk density of the Su Mai 188 was in the range of 70-96.75 kg/m3 and average bulk density of the Yang Fu Mai No2 was in the range of 129.32-167.03 kg/m3. The bulk density values of Su Mai188 were lower than those of Yang Fu Mai No2. The porosity of Su Mail 88 and Yang Fu Mai No2 were in the ranges of 60.1-62.7% and 63.8-64.2%, respectively. A positive linear relationship between the porosity and the average particle size for the wheat straw variety were also observed. The results obtained from this study showed significant differences in the physical properties of the straws of Su Mai188 and Yang Fu Mai No2 collected from the same farm. These differences may be due to variations in climatic conditions, and type of fertilizer used. |
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