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
The problem of environmental pollution caused by large-scale development of livestock and poultry breeding is increasingly severe in China. It is predicted that the fecal production of livestock and poultry in China will reach 42.44 billion tons in 2020, and the fecal pollution will rank the first among the agricultural sources. The greenhouse gases and odorous odors released by livestock manure are important sources of air pollutants, and ammonia is one of the main gases released by manure. Ammonia is not only a threat to the health of surrounding populations of livestock and poultry farms, but also an important part of the atmospheric acid deposition which can lead to soil acidification and eutrophication, and further become a serious threat to the ecological environment. Therefore, it is of great significance to carry out a study on the characteristics of ammonia emissions from typical large-scale pig farms, clarify the current situation of ammonia emissions from typical agricultural sources, which can provide the foundation for controlling the atmospheric particulate matter pollution and improving the regional air quality. The biogas produced by anaerobic fermentation is a common method for treatment of fecal pollution in large-scale livestock and poultry farms. The process can not only generate clean energy and reduce fecal stench, but also recycle nutrients in the form of fertilizer. Therefore, the treatment model centering on large-scale biogas project has developed rapidly. At present, there is still a lack of
in-situ monitoring and research on ammonia discharge at the nodes of the typical fecal treatment process. The systematic research on the impact of the anaerobic fermentation biogas production facility on the release of pig fecal ammonia has not been reported. A typical methane project of large-scale pig farms in the Yangtze River Delta was used as the research object in this study. The ammonia emission was monitored for three consecutive days at each emission node (cesspool, regulating pond, and biogas slurry pool) of the biogas engineering facilities. The results showed that the average daily emission rates of ammonia in cesspool, regulating pond, and biogas slurry pool were 1.48, 3.08, and 1.47 g/(d·m
2), respectively. The ammonia emission at each node had an obvious daily change process, which was generally manifested as the fluctuant increase in the morning, decrease in the afternoon, and the low-value emission at night. The cesspool and regulating pond in the turnover period of fecal pollution appeared daily emission peak; the ammonia emission rates of the cesspool, regulating pond, and biogas slurry pool were positively correlated with the temperature in stable stage, while negatively correlated with the humidity. The daily ammonia emissions of cesspool, regulating pond, and biogas slurry pool were 13.44, 38.72, and 5 275.4 g/d, respectively. We selected a typical large-scale pig farm with anaerobic fermentation for biogas production and conducted the field monitoring for the ammonia concentration at each node of treatment facilities. By calculating the excreta ammonia emission rate at each emission node, the characteristics of ammonia emission were analyzed, and the main factors influencing ammonia emission were identified. The results provide a reference for the calculation of ammonia emissions from livestock and poultry farms and the formulation of the ammonia emission reduction measures.
The effects of aerated subsurface drip irrigation (ASDI) on yield potential and quality of crop, and the relationships of soil aeration with crop yield and fruit quality are poorly known. In order to reveal the relationship between crop growth and soil aeration under ASDI, a pot experiment was conducted using tomato in the Efficiency Agriculture Water Experimental Farm of North China University of Water Resources and Electric Power (34°47′5.91″N, 113°47′20.15″E). Herein, two levels of irrigation amount (W
1 and W
2 as 0.6 and 1.0 times of the crop-pan coefficient, respectively) and two aeration treatments (A and C as ASDI and control treatment, i.e., non-aeration treatment by subsurface drip irrigation) were set up. During the trial, the air-filled porosity, soil dissolved oxygen (DO), oxidation–reduction potential (Eh), oxygen diffusion rate (ODR), soil respiration, photosynthesis indexes, crop aboveground biomass, root biomass, nutrient uptake, yield, and fruit quality were monitored systematically. The correlation analysis was conducted among soil aeration indexes, photosynthesis indexes, nutrient uptake efficiency, yield, and fruit quality. The results showed that the ASDI improved the soil aeration. Compared with those of control group, the DO in W
2A and W
1A treatments increased by 25.71% and 10.64% on the next day after irrigation at flowering and fruit bearing stage (
P < 0.05). In W
2A and W
1A, similarly, the ODRs increased by 52.90% and 32.27% and the Ehs increased by 41.99% and 20.99%, respectively (
P < 0.05). Compared with that of the control group, the soil respiration in W
2A and W
1A significantly increased by 64.70% and 28.45% at the flowering and fruit bearing stage, 14.17% and 33.24% at the fruit expanding stage, and 56.91% and 32.86% at the maturity stage (
P < 0.05). Meanwhile, there were obvious positive correlations among ODR, Eh, DO, and air-filled porosity (
P < 0.01). The ASDI had a positive effect on the crop photosynthesis, benefiting the increment in biomass, nutrient uptake, and crop quality. Compared with those of the control group, the net photosynthetic rates in W
2A treatment at flowering and fruit bearing stage, fruit expanding stage, and maturity stage increased by 14.51%, 21.72%, and 13.76%, respectively (
P < 0.05). The net photosynthetic rate in W
1A treatment at fruit expanding stage increased by 55.26% (
P < 0.05). The aboveground fresh weight and root fresh weight significantly increased by 68.14% and 55.18% in W
2A treatment, and by 9.88% and 45.37% in W
1A treatment (
P < 0.05). Compared with those of the control treatment, the nitrogen uptake in root, stem, and leaf increased by 52.94%, 42.03%, and 24.12%; the phosphorus utilization in root and stem increased by 74.07% and 36.00%; and the potassium accumulation in root, stem, and leaf increased by 56.52%, 41.09%, and 22.44% in W
2A treatment (
P < 0.05), respectively. Similarly, the crop yield, fruit soluble solids, vitamin C content, total acid content, and soluble protein in W
2A increased by 66.40%, 51.77%, 20.26%, 55.26%, and 63.64%, respectively (
P < 0.05). The fruit soluble solids, vitamin C content and total acid content in W
1A treatment increased by 43.55%, 29.68%, and 71.43%, respectively (
P < 0.05). The ASDI treatment at the irrigation of 1.0 time of the crop-pan coefficient showed the most efficient promotion on soil aeration, crop growth and fruit quality. There were significantly positive correlations of crop yield with DO, Eh, and respiration under ASDI (
P < 0.05). In addition, there were positive correlations between crop quality (soluble solids and total acid content) and soil aeration indexes (DO, ODR, and respiration) (
P < 0.05). In sum, these results would provide valuable information for the enhancement effects of ASDI on soil aeration, crop yield and fruit quality.
Determining positions to represent mean soil water content based on soil clay content is an alternative method for positioning the soil moisture sensors in wireless sensor networks for a variable rate irrigation system. The field was divided into four management zones according to the available soil water holding capacity (AWC). Two of the four management zones were selected to arrange the rain-fed treatment and three irrigation treatments representing different water stress levels to assess the effect of the levels on the placement of soil moisture sensors under the variable rate irrigation system. In zone 1, the sand fraction largely increased with depth with AWC within the 1-m soil profile ranging from 152 to 161 mm. In zone 2, a relatively uniform profile was observed along the profile with AWC within the 1-m soil profile ranging from 161 to 171 mm. Based on the time stability of soil water content, the effects of soil water status and soil properties on the similarity of soil water spatial pattern and the positions directly representing the plot-mean soil water content were studied. The results showed that both soil texture and water stress had effect on the structure similarity of soil water content distribution. In zone 1, the average Spearman’s rank correlation coefficient of 0–0.6 m was significant at the probability level of 0.05 only in the rain-fed treatment in the 2016 season. In zone 2, the Spearman’s rank correlation coefficient was significant at the probability level of 0.05 in all treatments in the 2016 season and in the medium and low water stress treatments in the 2017 season. The percentages of positions directly representing the mean soil water content were almost the same in zones 1 and 2. Affected by soil water status, the percentages increased as the level of soil water stress decreased in zone 1. In zone 2, as the severity of water stress decreased, the percentages decreased and then had a slight increase. In general, significant linear regressions (
P < 0.05) between the mean clay content and the clay content representing the mean soil water content sites were found in layers 0–0.2, 0.2–0.4, and 0.4–0.6 m for all the treatments in 2016 and 2017, except for that in the severe water stress treatment in 2016. The fitted equation coefficients ranged from 0.66 to 1.03 in the two seasons, demonstrating a clearly increasing trend as the severity of water stress increased in 2017. When the mean clay content is used for a priori identification for positioning the soil moisture sensors in the management zones under the variable rate irrigation system in a field with sandy loam soil, the strategies of water stress management should be considered in determining fitted equation coefficients.
The groundwater source heat pump has high efficiency and environmental protection in greenhouse temperature control. The operating energy consumption could be further reduced if the water storage technology was combined. The energy-saving operating characteristics of a water storage groundwater source heat pump heating system was studied, with the natural light plant factory in Shanghai as an example. The total area was 21 000 m
2, of which the heating area was 5 880 m
2. The heating system included a groundwater heat exchange system, a heat pump unit, an air conditioning unit, and an energy storage system. Considering the change in electricity price and the change in heat load over time, intermittent operation was adopted for the heating system. At the time of power trough, the heat pump unit was fully open and the energy was stored in the tank while heating. At the peak of power, the heat pump unit was stopped and the system made full use of the heat storage tank for heating. At the time of the level section, reasonable regulation was carried out according to the stored energy of the hot water storage tank and the plant heat load demanded. The typical operating week, February 8–15 in 2017, was selected from the winter heating months. The operation data in the typical week were recorded and analyzed. The outdoor temperature, solar radiation intensity, indoor temperature, indoor relative humidity, and COP (ratio of heat supply to power consumption) of the heat pump were all tested every 5 min in the typical week. The result showed that in winter, the groundwater source heat pump with the energy storage tank heating system could better maintain the indoor temperature at 17 °C–26 °C. The indoor temperature was relatively low at night, but it could meet the growth demand of the crop in winter. The influence of solar radiation was large, and the indoor temperature was basically above 22 °C, even 28 °C. The indoor relative humidity was always 60%–88%, which could avoid indoor high temperature with high humidity. When the system was in stable operation, the heat pump unit COP (coefficient of performance) was about 4.2. February 9, 2017 was selected from the typical week. On the typical day, it was cloudy and the temperature was below 4 °C throughout the day; the solar radiation intensity was 0–160 W/m
2 and the average solar radiation intensity was 62 W/m
2. The total power consumption of the system was 10 142.71 MJ, and the COP of the system was 3.17. It was further explained for the system characteristics of high efficiency and good stability. Compared with the non-storage ground source heat pump system, the groundwater source heat pump with water energy storage system saved 30.34% of the cost on the typical day. The significant economic benefit of the test system was shown. During the continuous heating period in winter, for the test heating system, the primary energy utilization coefficient was 0.99. Compared with the cold water unit and coal-fired boiler supporting system and chiller and gas boiler supporting system, the energy-saving rate was respectively 81.05% and 74.83%. Different energy heating cost was compared. For the operating cost, the coal, gas, and fuel methods were 1.25, 2.93, and 5.08 times that of the test heating system. For the CO
2 emission, it was 2.32, 1.19, and 0.88 times that of the test heating system. Practice showed that the groundwater source heat pump with water energy storage system had good economic and environmental benefits, which could not only reduce the operating costs, but also make full use of geothermal energy and be beneficial to energy conservation.
Objective and accurate identification of tea grades is indispensable in tea processing and sales. Traditional grade identification often depends on human sensory judgments. This method is subjective, difficult to quantify, and has a certain error probability. The objective of this paper was to establish an objective and accurate method to identify the appearance grade of tea. In this paper, Keemun congou black tea was taken as the research object, and a SVM recognition method based on shape feature histogram multi-feature fusion was proposed. Firstly, the tea image acquisition system was built and the camera parameters were calibrated. The rectangular groups and irregular polygon groups of fix dimensions were used to test the measurement accuracy of the image acquisition system. The RGB image of tea leaves was greyed and its binary image was obtained. In order to obtain uniform shape feature parameters, the rotation of tea image was carried out with the minimum area of the leaf’s outer rectangle as the constraint. Secondly, six absolute shape features—leaf length, leaf width, leaf area, leaf perimeter, the length and width of minimum area bounding rectangle, were extracted. On this basis, two relative shape features of length-width ratio and rectangularity were calculated. The histograms of different tea samples in different interval were further obtained, and the histogram distribution of the above characteristics was used as classifier inputs. Finally, the BP neural network, extreme learning machine (ELM), support vector machine (SVM) and least squares support vector machine (LS-SVM) were used as classifiers to classify tea samples. This result showed that the measurement accuracy of the image acquisition system constructed in this paper was less than 0. 3 mm, and the shape feature parameters could be accurately extracted. When identifying all seven grades of tea samples, the recognition accuracy of BP neural network was 53.6%, the recognition accuracy of ELM was 87.86%, the recognition accuracy of SVM was 94. 29% and the recognition accuracy of LS-SVM was 95.71%. The details of BP neural network classifier were as below: When two grades were classified, the recognition accuracy was 100% and the determination coefficient of the test set was 100.00%. When four grades were classified, the recognition accuracy was 97.5% and the determination coefficient of the test set was 93.19%. When all seven classes were classified, the determination coefficient of test set was 53.6%. The details of ELM classifier were as below: When three grades were classified, the recognition accuracy was 90.00%. When five grades were classified, the recognition accuracy was 88.00%. When the SVM classifier with linear kernel function was used to identify seven grades, the determination coefficient of test set was 86.10%. When the LS-SVM classifier with linear kernel function was used to identify seven grades, the determination coefficient of test set was 96.20%. It could be seen that the classifier based on LS-SVM had higher recognition accuracy and the best effect. There were two types of problems in the classification process: One was as the misidentification rate increased with samples amount increasing in the classification model, the second was the misidentification largely happened in adjacent classes. These problems were discussed in this paper. Through the above research, it was verified that the shape feature could be used to identify the appearance grade of Keemun congou black tea. This paper provided detailed experimental data and reference methods for the objective and digital grade identification of Keemun congou black tea.
In recent years, China’s rural areas have witnessed rapid economic development, and the living and production wastes in rural areas have gradually increased. However, due to the limited economic development level, some villages are lack of facilities for collection, treatment, and disposal of these wastes. The recycling of living and production wastes in villages is an important way for environmental protection in the rural areas and for improving the efficiency of resource utilization. It is easy to find some practical and mature technologies to treat one kind of wastes in rural area, but there lacks overall consideration for the recycling of production and living wastes in villages. In this paper, we took a typical village (village A) in the mountainous area of Xingtai City, Hebei Province as an example, and constructed a recycling system of production and living wastes. Fruit planting and rural tourism are the leading industries in village A. The main wastes in village A are fruit tree pruning, household solid waste, sewage, and manure. The recycling system of the village was constructed with technologies and facilities such as composting of organic wastes, pyrolysis of fruit tree pruning, sewage treatment, and the collection and treatment of solid wastes. The energy recovery and fertilizer use were realized in the village, and the residential environment governance achieved a higher level. A combination of analytic hierarchy process (AHP) and fuzzy evaluation method was adopted to construct the index system to evaluate the technology system of the recycling of wastes from living and production. A total of 26 indexes were chosen in the index system, which contained technological, economic and social, and environmental indexes. The weight of each index was determined by the expert scoring method. Residents’ acceptance, cost for garbage collection, average steady running time of the treatment facilities, and qualification rate of surface water and soil showed higher weights in rural area of north China. The method was used to evaluate the recycling system of village A, and the result showed that the technology system of recycling of wastes from living and production in village A was level excellent. The evaluation method could fully reflect the characteristics of the recycling mode of living and production wastes in rural areas. The evaluation methods in this study would provide a methodology reference for assessing, selecting, integrating, and promoting the technology system of recycling of wastes from living and production in China. It is a new thought to commit an overall design of the recycling system of the village, according to the village type, location, and regional economic, and to modify it through scientific evaluation, which can greatly improve the quality of rural area development, governance, and environmental protection. We will conduct evaluation and research on different types of typical villages in the southern area and the plain area of northern China in the future, further improve the evaluation method, and provide guidance for the construction and operation of the recycling systems of living and production wastes in natural villages.
Contamination of heavy metals in agricultural soil has been a worldwide challenge for the food security and people’s health. Especially, cadmium (Cd) and lead (Pb) contamination in soil is a serious problem in China. Therefore, it is imperative to develop remediation techniques able to remove contaminants in a highly efficient and cost effective way. The traditional washing method is widely used for soil remediation on account of its high efficiency and simple operation. However, the efficiency of traditional washing method is limited by soil permeability, so this method can only remediate a small range of heavy metal-contaminated soil and has poor removal effect for the clayey soil, which cannot be popularized at a large scale. In order to solve the problem of low washing efficiency resulted from the heavy texture and low permeability of clayey soil, we proposed a cooperative remediation by freeze-thaw and chemical washing method. Taking the Cd and Pb contaminated soil in a smelter as the research object, we conducted the empirical tests of freeze-thaw and washing (FTW) for soil columns with 0.1 mol/L ethylenediamine tetraacetic acid disodium salt (EDTA). The results showed that repeated freezing and thawing (frost heave–water absorption, thaw settlement–drainage) of soil destroyed the original cohesive force and soil skeleton structure between the soil particles, so that the soil particles were rearranged, which contributed to the fully contact with the eluent and contaminants. The washing effect was significantly improved by this method. The removal rates of Cd in FTW3 (FTW treatment with three freeze-thaw cycles; adding EDTA at 1st and 3rd cycle), FTW5 (FTW treatment with five freeze-thaw cycles; adding EDTA at 1st and 2nd cycle), and FTW7 (FTW treatment with seven freeze-thaw cycles; adding EDTA at 1st to 3rd cycle) groups were 9.05%, 64.90%, and 77.24%, respectively; and the removal rates of Pb in FTW3, FTW5, and FTW7 groups were 2.06%, 14.42%, and 37.78%, respectively. The forms of heavy metals at different depths in the soil column after washing were analyzed by the three-stage continuous extraction method (BCR method) proposed by the European Community Bureau of Reference. The weak acid extractable Cd increased by 20.76%, the average reducible Cd decreased by 41.58%, and the residual Cd increased by 193.45% in FTW3. The weak acid extractable Cd decreased by 0.39%, the average reducible Cd decreased by 45.75%, and the residual Cd increased by 43.73% in FTW5. The weak acid extractable Cd, average reducible Cd, and residual Cd decreased by 41.46%, 63.02%, and 26.33%, respectively, in FTW7. The average reducible Pb increased by 11.23%, the average oxidizable Pb decreased by 63.12%, and the residual Pb increased by 53.97% in FTW3. The average reducible Pb decreased by 0.12%, the average oxidizable Pb decreased by 64.13%, and the residual Pb increased by 30.68% in FTW5. The average reducible Pb, average oxidizable Pb, and residual Pb decreased by 32.32%, 62.05%, and 67.36%, respectively, in FTW7. Moreover, the freeze-thaw and washing method had a lower ratio of liquid to soil, which were 0.32, 0.47, and 0.62, respectively, so that the amount of eluent was much smaller than that of the traditional washing method. Besides, this study provides a method for the
ex-situ remediation of heavy metal-contaminated soil in seasonally frozen areas by using the phenomenon of freeze-thaw alternation in cold regions in the future.
