Transactions of the Chinese Society of Agricultural Engineering, the 1st in Agricultural Engineering, is supervised by China Association for Science and Technology, and sponsored by Chinese Society of Agricultural Engineering. It aims to introduce the latest scientific achievements and developing trends of Agricultural Engineering and provides the academic developments abroad and domestic of the discipline. The scope covers agricultural water-soil engineering, agricultural information and electrical technology, agricultural products processing engineering.
The journal is included in EI, JST, Pж(AJ), CA and CSCD.
Editor-in-Chief Zhu Ming
Deputy Editor-in-Chief Wei Xiuju Zhang Ruihong Xi Weimin Wang Liu Wang Yingkuan Li Pingping Ying Yibin Tong Jin Yun Wenju Zhao Chunjiang Kang Shaozhong
China has attached great importance to poverty reduction work for a long time, and has explored a road of poverty alleviation and development with Chinese characteristics. Practice has proved that China’s poverty reduction results are fruitful. However, China’s poor population at present is still large, which is a serious threat for China to achieve the goal of building a well-off society in an all-round way. The Chinese government has put forward the goal of eliminating rural poverty by 2020, and required to take measures to ensure the achievement of the goal. This study analyzed the platform effect that land consolidation played in poverty alleviation in poor areas, and argued that land consolidation supported the development of special industries, provided conditions for ecological migrants, builded infrastructure, increased employment and protected the ecological environment through guiding external inputs and exploring internal potentials. All of these can effectively eliminate or alleviate poverty factors existing in poor areas. Based on the mechanism analysis of land consolidation promoting poverty alleviation in poor areas, this study divided the patterns of land consolidation promoting poverty alleviation in poor areas into three types, namely, the pattern of government leading, the pattern of enterprise driving and the pattern of villager autonomy. In the pattern of government leading, relevant government is not only mainly responsible for poverty alleviation, but also the main performer of land consolidation investment, and the pattern is the main pattern of promoting poverty alleviation in poor areas. To guide and encourage social capital to enter land consolidation is an important task to promote poverty alleviation and land consolidation in poor areas, the agricultural enterprises on behalf of the social capital is a necessary complement to the government to promote poverty alleviation and land consolidation, and the pattern of enterprise driving needs to become important pattern of promoting land consolidation in poor areas out of poverty. To achieve the goal of poverty alleviation and land consolidation work needs to fully play the main role of local farmers, and the pattern of villager autonomy is expected to change the fact that government and its departments rely on their own power to promote poverty alleviation and development of land consolidation practices. The pattern is the potential pattern of poverty alleviation in poor areas. This study took Guizhou Province as a case, and analyzed the role that land consolidation played in poverty alleviation in poor areas of Guizhou Province. Especially, the study took examples, such as modern efficient agriculture park of Qixingguan District, agriculture park of Pingshan Town of Hezhang County, and Lianglukou Village of Fuxing Town of Meitan County, to demonstrate the efficiency of the mentioned three patterns. The results emphasize that all places should pay enough attention to the platform effect of land consolidation when they try to realize the poverty alleviation goal, and choose the appropriate pattern of land consolidation to promote poverty alleviation according to the actual situation.
Water resource is the key factor affecting dryland maize growth in semi-arid and sandy land area. These areas are fragile in eco-environment and unreasonable land use has induced serious land desertification. Therefore, it is of great significance to study crop growth status under different precipitation types and to identify the unstable cultivated land for eco-environment rehabilitation in semi-arid and sandy land area. Taking Horqin Left Back Banner as a case study, firstly, we analyzed the precipitation types of maize growth period from 1980 to 2013 with the precipitation data from Horqin Left Back Banner Weather Station. Secondly, the dryland maize growth status was studied with the method of remote sensing technology and the crop production stability was analyzed. Thirdly, unstable cultivated land identification was performed according to the dryland maize growth statuses under normal precipitation year and partially dry year. The results indicated that the proportions of dry year, partially dry year, normal year, partially wet year, and wet year were 11.77%, 29.41%, 17.65%, 32.35%, and 8.82%, respectively. The proportions of partially wet year and wet year, partially dry year and dry year were large. The precipitation fluctuation in maize growth period was dramatical in Horqin Left Back Banner. The sums of normalized difference vegetation index (NDVI
sum) of cultivated land in partially dry year (2001), normal year (2013), and partially wet year (2008, 2012) were mostly distributed in [4, 4.5), [4.5, 5.5), and [4, 5), respectively. There were big gaps in dryland maize growth condition in different precipitation types of maize growth period. In general, the dryland maize growth status in partially dry year was worse than that under normal year. The precipitation in semi-arid and sandy land area could not meet the demand of dryland maize growth. The precipitation in partially dry year was less than normal year. These reasons made the dryland maize growth in partially dry year worse than that under normal year. The dryland maize growth under normal year was better than that under partially wet year. Micro-terrain made the redistribution of precipitation and the cultivated land distributed at low terrain would be in waterlogging in much precipitation condition. Therefore, the dryland maize growth under partially wet year was worse than that under normal year. The dryland maize growth under partially dry year was worse than that under partially wet year. The area of cultivated land distributed on high terrain was larger than that on low terrain, and compared with the waterlogging, drought had a more wide effect on dryland maize growth. Therefore, the dryland maize growth under partially dry year was worse than that under partially wet year. According to the precipitation types and dryland maize growth status, the crop production is unstable in semi-arid and sandy land area. Based on the difference of dryland maize growth under normal year and partially dry year, the cultivated land was grouped into four types: extremely unstable cultivated land, unstable cultivated land, relatively stable cultivated land, and stable cultivated land. The areas of extremely unstable cultivated land and unstable cultivated land were 68.75 and 33 918.75 hm
2, respectively. By this study, the understanding of agricultural production in semi-arid and sandy land area was deepened. Drainage facilities or water storage facilities should be constructed in low-lying areas in semi-arid and sandy land areas to avoid the effect of waterlogging on crop growth. Extremely unstable cultivated land and unstable cultivated land should be changed to achieve ecology restoration.
In order to solve the problems that the manually digging of lotus roots is intense in labor, low in efficiency and easy to damage lotus roots, and the existing digging equipment has the defects of high cost and the cumbersome operating process, a spin-jet flow type lotus root digging machine was designed in this study. The structure and working principle of this machine were described, and the mechanism of interaction between soil and jet was analyzed by the coupling simulation of the enhanced discrete element method (EDEM) and the fluid dynamics. At the same time, the influence rules of the structural parameters of the key component nozzle were defined. The model of Hertz-Mindlin with JKR (Johnson Kendall Roberts), a cohesive contact model considering the influence of van der Waals force and the viscous contact, was used in the simulation. The EDEM parameters from field measurement and related literature were as follows: the approximate value of the particle radius of 3 mm with consideration to computer power and simulation efficiency; the volume density of 1 714 kg/m
3; the JKR coefficient of 60 in GEMM (Generic EDEM Material Model) database with the repose angle of the soil; the coefficient of restitution of 0.15; the coefficient of static friction of 1.16; the coefficient of rolling friction of 0.2; the elastic modulus of the soil of 1 143.2 kPa; and Poisson’s ratio of 0.4. The simulation showed that the depth of digging decreased with the increase of jet angle from 30° to 60°, while increased with the increase of jet velocity from 10 m/s to 20 m/s. Through the analysis of the simulation process, it could be found that when the angle was 30°, the soil backfill would happen. Based on the three-inch pump HONDA WB30XH, the bench test and field test were carried out. The results showed that the spin-jet lotus root digging machine with the jet angle of 30° and nozzle diameter of 17 mm could advance with the speed of 0.1 m/s, which could completely dig the lotus roots buried in mud depth of 400 mm without damage and dirt stuck on the surface, and the soil backfill did not affect the surfacing rate of lotus root. The digging depth could reach 420 mm, while the digging width could reach about 12 m. It can be obtained from the bench test that the rotation speed of the rotating pipeline also has a certain effect on the digging effect. When the jet angle is larger, the rotation speed of the pipeline is faster, which conforms to the law of fluid mechanics. When the diameter of the nozzle is larger, the rotation speed of the pipeline is also larger. It is shown that the nozzle with a larger diameter produces stronger reaction force to the pipeline. The comparison of the relative surfacing rate with the pipeline speed showed that the smaller rotation speed corresponded to the higher surfacing rate. Due to the reason of pipeline structure, the rotation speed regulation test could not be carried out. Furthermore, the average error of digging depth was 9.5% between simulation test and bench test, so the comparison results showed that the application of the coupling of discrete element and finite element method of fluid dynamics was feasible in the research of soil–jet interaction. Because the digging process of lotus root below the water is not easy to observe, the application of EDEM-Fluent coupling simulation is beneficial to the study of the mechanism of the lotus root digging equipment, providing a theoretical basis for the design and optimization of the equipment. The method can also be applied to other areas of hydraulic research, such as river and lake dredging, and pipeline cleaning.
The rill morphology changes directly affect the slope hydrological process, and thus form a mutual feedback effect with runoff yield and concentration, sediment yield and transport. This process embodies the relationship between the elements of water erosion dynamics on the slope, and is a key scientific problem in understanding the physical process of erosion and sediment yield. The morphological development of rill on slope forms a micro relief dynamic response system with soil erosion driven by rainfall. To reveal the formation mechanism of this system, scientific quantification is the key problem. In the past research, one-factor quantification parameter based on mathematical statistics was used, which was hard to effectively express the complexity of the whole system. In this study, the influences of rill morphology evolution on runoff and sediment process were studied. The rainfall, rill evolution, runoff, and sediment yield were used as a hydrodynamic coupling system to study the rill morphological characteristics and implementation methods, to reveal the law of spatial and temporal differentiation of rill morphology, and clarify the quantitative response of rill morphology to rainfall runoff and sediment yield. The aim of this study was to break through the unresolved spatial variability problem in the existing water erosion prediction model, and to provide a scientific basis for the prediction of soil erosion process. The indoor simulated rainfall experiment was conducted to reveal the variation regularity of the rill boundary and the responses of the erosion and sediment yield under the fixed slope gradient (20°) and three rainfall intensities (66, 94, 127 mm/h). The parameters such as rill cumulative length, mean width and depth were used to describe the change of the rill morphology with the rainfall. The results showed that the effect of rainfall intensity on rill length was significant, the change of rill width was influenced by the rainfall duration, and the change of rill depth presented a strong differentiation rule with the rainfall intensity. The rill morphological parameters were not independent of each other, and there was a clear correlation between them. The evolution of rill morphology was a multi-dimensional change process rather than a one-dimensional development process. The sediment yield was affected by the development of rill. The rill morphology showed a logarithmic function relationship with the sediment concentration and erosion rate. The results showed that the rill formation and development were closely related to the water and sediment yield on the slope, and the influences of rill forwarding, rill wall expansion and rill bed undercutting on the sediment yield were basically the same. This study can provide basic data for the establishment of rill erosion dynamic model.
The important mechanism of soil salinization is that the soluble salt in groundwater accumulates continuously to the topsoil under the action of capillary force. In order to study the effects of various factors on the characteristics of soil upward capillary water movement under shadow ground water table, we used HYDRUS-1D software based on the theory of saturated-unsaturated soil water movement to simulate the upward capillary water movement under the action of multiple factors. A total of five factors were considered, including soil bulk density, clay content, initial soil moisture, groundwater depth, and infiltration time. The simulation experiment was carried out by the orthogonal design method including nine treatments and one controlled trial. In the simulation experiment, the soil bulk density was designed at 1.30, 1.35, and 1.40 g/cm
3, the clay content at 1.25%, 5.00%, and 15.00%, the initial soil moisture at 8%, 11%, and 14%, and the groundwater depth at 1.5, 2.5, and 3.5 m. The controlled trial, which adopted clay loam in arid area, was carried out in State Key Laboratory Base of Eco-hydraulic Engineering. During the experiment, the capillary water recharge was measured by the difference of water levels in Markov bottle. The water levels were recorded every 1, 2, and 3 h on the 1
st day, every 5 h on the 2
nd day, every 9 h on the 3
rd day, and every 12 h from the 4
th day to the 5
th day. The capillary water rising height was obtained by plotting the position of the wetting front corresponding to the different infiltration time on the outer wall of the plexiglass column. Based on the analysis of simulation results, the empirical models of the upward capillary water recharge and the capillary water rising height with various influencing factors were established, respectively. The root mean square error of the model was 0.003 cm; the correlation coefficients were all greater than 0.99; the coefficients of determination were all greater than 0.98 (
P < 0.01), and the relative errors between the measured and calculated values were less than 11.25%. The results showed that the models could better illustrate the quantitative relationship of the upward capillary water recharge and the capillary water rising height with various influencing factors. The influence degree of each influencing factor on the upward capillary water recharge was the highest for time, followed by soil bulk density, initial moisture, clay content, groundwater depth; and the influence degree on the upward capillary water rising height was the highest for time, followed by initial moisture, clay content, soil bulk density, and groundwater depth. The capillary water recharge had positive correlations with clay content and time; while it had negative correlations with soil bulk density, initial moisture and groundwater depth. The capillary water rising height had a positive correlation with initial moisture, groundwater depth and time, whereas it had negative correlations with soil bulk density and clay content. Moreover, the relationship between the capillary water recharge and the rising height were fitted by the means of (intercept = 0) linear function, and the coefficients of determination were larger than 0.96, which indicated a significantly positive linear relationship between the upward capillary water recharge and the rising height. The results would provide a basis for making measures such as irrigation and drainage as well as saline-alkali land improvement.
