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
In order to explore the regularity of nitrogen and phosphorous wet deposition in rice season in the Erhai lake basin, the wet deposition samples were collected at the Dali Environment Comprehensive Monitoring Station of the Ministry of Agriculture and Rural Affairs, Xizhou, Dali, in rice seasons in 2016 and 2017. The contents of deposition samples, such as total phosphorus (TP), total nitrogen (TN), NO
3−-N, and NH
4+-N, and their changes were analyzed. The results showed that the wet deposition fluxes of TN and TP in rice season in 2016 were 2 250.21 and 133.87 kg/km
2, respectively, and the wet deposition fluxes of TN and TP in the rice season in 2017 were 1 034.26 and 73.37 kg/km
2, respectively. In the rice seasons in 2016 and 2017, the amount of TN wet deposition which descended directly to the surface of Erhai Lake accounted for 16.7% and 7.7% of the annual TN lake load, and that of TP was 11.0% and 6.0%, respectively. July and August in 2016 and 2017 had the largest wet deposition fluxes in the rice season, which had the highest precipitation. The precipitation in 2016 was 486.8 mm larger than that in 2017. Correspondingly, the wet deposition fluxes of TN and TP in 2016 were 1 216 and 60.6 kg/km
2 higher than those in 2017, respectively. The wet deposition fluxes of TN and TP were mainly controlled by precipitation. The TN and TP wet deposition fluxes of single precipitation in rice seasons in 2016 and 2017 showed a significant linear positive correlation with precipitation. The wet deposition concentrations of TN and TP decreased with the increase of rainfall, and it was related to whether there was continuous rainfall and large-scale fertilization. Taking the wet deposition of nitrogen in rice season in 2017 as an example, we could find that the correlation analysis of nutrient concentration and precipitation in the wet deposition showed that TP, TN, NO
3−-N, NH
4+-N, and precipitation were all in weakly negative correlation at the 0.05 level, and there was a strong correlation between TN, NO
3−-N and NH
4+-N at the 0.01 level. The ratios of wet deposition of NH
4+-N and NO
3−-N to TN were 53.1% and 20.6%, so NH
4+-N was the main wet deposition. The ratio of dissolved inorganic nitrogen (DIN) to TN decreased with the increase of precipitation and increased with the continuity of precipitation. Ammonia volatilization was one of the main sources of atmospheric nitrogen wet deposition, but the change of nitrogen wet deposition flux in Erhai lake basin did not change with the change of ammonia volatilization rate in paddy fields. This was related to the complex planting structure and special three-dimensional climate in the basin. The randomness of precipitation and the uncertainty of the basin's wind direction determined that the changes of wet deposition fluxes were more complex. The wet deposition TN concentration in the rice seasons in 2016 and 2017 was 0.87–4.03 and 0.90–6.85 mg/L, respectively, much higher than the 0.20 mg/L threshold for eutrophication. The mass ratio of N and P in wet deposition was low N/P ratios (16.82 and 14.09, respectively), which was in favor of rapid growth of cyanobacteria, so the wet deposition in the rice season would have an adverse effect on the aquatic ecosystem in Erhai lake basin.
Volatile flavor compounds are the main factors that constitute the flavor characteristics of food. Vacuum freeze-drying (FD) is internationally recognized as the best method of producing high-quality dehydrated food. However, the retention of volatile flavor compounds by FD cannot meet our expectation. It had been verified by many researchers that volatile flavor compounds in food materials would be lost in FD process, depending on the material type and the processing parameters. Lemon is a citrus fruit with extremely high nutritional and medicinal value. It is rich in the volatile flavor compounds such as terpenes, alcohols, aldehydes, esters, and ketones. The lemon slice or powder products made by FD are popular with lots of consumers. In order to explore the effect of FD methods on the retention characteristics of volatile flavor compounds in lemon, two different processing methods including the integrated FD method and the conventional FD method were employed to dry lemon slice for comparing the distribution of volatile flavor compounds. The previous research results showed that nearly one third of the initial moisture in lemon slices was removed during the vacuum freezing process in the method of the integrated FD method, which contributed 2.5 h to saving time of pre-freezing process and 2 h to saving time of sublimation drying process in contrast to the conventional FD method, respectively. Smaller and denser porous network structure was formed in the dried lemon tissue after the integrated FD, and their cell wall chambers were more complete without broken or cracked piece. The monoterpene compounds predominated among all the volatile flavor compounds in the raw lemon materials, mainly including D-limonene, terpinenes, L-
β-pinene, and
β-pinene. The main sesquiterpene flavor compounds in raw lemon materials were 1-caryophyllene, valencian eneene, and
β-windproofene. The main aldehyde compounds were citral, dimethyl-octendialdehyde, nonanal, decanal, and hexanal. The main alcohol compounds were
α-terpineol, nerol, 4-nonenol, linalool, and geraniol. The main ester compounds were nerol acetate and 5-methyl-2-4-hexen-1-ol acetate. The retention rates of all major volatile flavor compounds in the two FD lemons were very low, and most of them migrated out from the FD lemon and were captured by the cold trap or discharged outside by the vacuum pump. The contents of all above volatile flavor compounds in the lemon slices dried with integrated FD method were significantly higher than those in the lemon slices dried with the conventional FD method (
P < 0.05), which showed that the integrated FD method had significant advantages in the retention of volatile flavor compounds. The content of the main monoterpene flavor compounds in cold trap ice of the conventional FD method was significantly higher than that of the integrated FD method (
P < 0.05), while the opposite result was tested for the main sesquiterpene compounds, aldehyde compounds, alcohol compounds and lipid compounds in the cold trap ice of two FD methods (
P < 0.05). The difference in the retention characteristics of the main volatile flavor compounds in two kinds of FD lemon may be related to their FD process time and micro-structure morphology. In general, the retention rates of the above-mentioned main volatile flavor compounds in the freeze-dried lemon slices with the two FD methods were both relatively low, most of them were lost in the cold trap ice and discharged into the environment. However, the integrated FD method had significant advantages for the retention of the major flavor compounds in lemon slices in contrast to the conventional FD method. The results of this study can provide some references for the improvement of fragrant quality in fruits and vegetables during the freeze drying process.
Being the principal organ to absorb water and nutrition, roots plays a very important role in the growth of plants. Since roots usually grow in soil that is invisible to us, it is very difficult to detect root morphology in real time or to study on it over a long period of time, especially for shallow-root plants. In order to acquire the root morphological characteristics in real time, a kind of in situ micro root observation system was proposed and designed. The system was composed mainly of micro camera, optical amplifiers, and adjustable lighting device, and its whole volume was only 1.5 cm
3. The captured images were sent to the terminal (mobile phone or personal computer) via the wireless module for later image processing. The images of root were always with low quality affected by complicated soil environment (soil pores, obstacles, and moisture), which could not be eliminated with simple image processing method such as median filter and mean filter algorithm. In order to filter out these interferes to the image, the method of regional growth was used to extract root images. First, the image was corroded and expanded by 3 × 3 structural elements to acquire the start point and the end point of the algorithm, where the corrosion image was determined as the start point, and the expansion image as the end point. Then, the processing of regional growth was carried out by similarity criteria (grayscale difference less than 20), and the regions including soil pore structure, moisture, and other obstacles were formed. These regions were marked and numbered, and distinguished by the threshold (the threshold 50 pixel was determined by trial and error). At last, the root regions were kept, and the soil pore structure, moisture and other obstacles were deleted by filtering. The kept root regions were further processed by skeleton extraction based on maximum circle to calculate the root length, diameter and other parameters. Non-in situ test was carried out to test the accuracy of the designed system. The result showed that the system was able to capture the images with high accuracy (the maximum absolute errors of root length and average diameter were less than 1.5 mm and 0.09 mm, respectively, and the maximum relative errors of root length and average diameter were less than 5.3% and 6.7%, respectively). In situ experiment was then carried out by arranging micro root observation systems in different positions and depths into soil around roots. Calibration of micro root observation system was made by comparing with soil samples. The results of in situ monitoring showed that the micro root observation system could dynamically observe the growth of shallow root in multiple points. The determination coefficient of average diameter was more than 0.87 in all soil depths (0–10, > 10–20, > 20–30 and > 30–40 cm; relative error less than 10.4%). The determination coefficient of root length density within 30 cm was over 0.81 (relative error less than 13.5%). This micro root observation system could dynamically acquire the root morphology in multiple spots fast and accurately, which would provide reliable data for plant nutrition, plant physiology and ecology.
Climate change is currently a global concern, which is mainly caused by excessive emission of greenhouse gases and ammonia (NH
3) to the atmosphere, in particular the emission of CH
4, N
2O and CO
2 from agricultural production process. The greenhouse gas produced from manure management in livestock and poultry production is an important source of greenhouse gas emission. Besides, the fermentation process of animal manure may generate large amount of NH
3, which is considered as an important polluting gas to the environmental and ecological system. Among agricultural sector, dairy farm is a big source of greenhouse gas and NH
3 emissions. In China, a barn with a fully open lot, where the cows are freely accessible, is a typical operation for cows. The manure on the surface of the open lots is typically removed from days to weeks depending the climate and management in the farms, while the remained manure, liquid penetration and the cows on the lot are important sources of contaminated gas emissions. However, there are few field studies on the emissions from the lot because of its open characterization, relative low gas concentration and the potential impact on the daily management of the farms. In this paper, an integrated horizontal flux method, based on the mass balance principle, was used to calculate the emission fluxes of CH
4, N
2O, CO
2, and NH
3 from a typical dairy open lot in Beijing in spring by continuous measurement of their concentrations with the purpose to provide fundamental information on the emissions. As the emission source, the open lot, which was 40 m in length by 27 m in width and kept with 52 milking cows, was divided into upwind and downwind boundaries according to the dominating wind directions. The emission rate was calculated based on the concentration differences of the target gases continuously measured from the upwind and downwind boundaries at three different heights of 1, 2 and 3 m by a photoacoustic field gas-analyzer (INNOVA 1412i) and self-developed multiplexer. The results showed the overall emission rates of CH
4, N
2O, CO
2, and NH
3 from the dairy open lot were 155.59, 3.60, 4 869.37, and 66.27 mg/(m
2·h) during the field measurement, respectively. The emissions of all the gases reached their daily peaks after manure removal in late afternoon. The emissions of CH
4, N
2O, and CO
2 (based on CO
2 equivalents) of the open lot accounted for 42.79%, 9.37%, and 47.83% of the total greenhouse gas emissions, respectively and their proportions were related to the climate, manure management strategies of the lot, and feed in gradients as well. Additionally, the CH
4, N
2O, and NH
3 emission rates were significantly and positively affected by ambient temperature (
P < 0.05). The CH
4, N
2O and NH
3 emission rates could also be enhanced by wind speed within some limits. When the surface wind speed was around 5.16 m/s, which was measured on the point 1 m above the ground, the emissions of the three gases significantly differed from those under 4.05 and 4.75 m/s (
P < 0.05). While, when the wind speed was 18.85 m/s, the emission rates were decreased, which could be explained by the crust formed on the manure surface due to the drying process under much higher wind speed and its prevention on the emissions. Besides, the manure removal activity increased the emissions of gases, and the impacts of ambient temperature and wind speed on the gas emission may also be altered to some extent.
Jujube pit removing is the key technology of dried jujube deep processing. Currently, it is very common that the dried jujube pit extractor has a lot of defects. We designed a chained pneumatic punching automatic dried jujube pit removing machine to solve the existing technical problems. The whole machine was composed of a chain roller for feeding, a camera for collecting the images of jujubes transmitted on the conveyor, locating mechanism, and a jujube pit mechanism with spinning inserting rod driven by an intermittent cylinder. All of them were controlled by an embedded microchip. The feeding mechanism was mainly supported by a roller conveyor chain. The locating mechanism worked in conjunction with the feeding mechanism. The lower conveyor chain of the feeding mechanism and the upper roller of the locating mechanism consisted of a synchronous clamping and a locating roller device. The dried jujube pit removing machine was made up of a magnetic valve, a driving damping cylinder, sets of rotary inserted rods and knockout rods, a speed-regulating rotary driving motor, a sliding table, and an air compressor. The embedded microchip controlling the whole jujube pit removing system was formed by a STM32F407 image processor, a STM32F103 coprocessor, a Shanghai LJ12A3-4-Z/BX 3-way NPN sensor and a HBS860H stepper motor. The whole structure could be divided into three parts according to the operating process, which included the jujube feeding area, the detecting area, and the clamping and jujube pit removing area. Under the programmatic control of the microcontroller, the jujubes were transported by the chain roller. The elastic strip was fixed at the bottom of the feeding hopper, and the rubbing roller rotated to realize the individual directional arrangement of the jujube. The camera was adopted for image detection of the automatic alignment of the jujubes, and the collected synchronous information from the camera was transmitted to the coprocessor and analyzed timely. The jujube with location information was conveyed to the jujube pit removing area, and the jujube was clamped by the synchronous roller. The coprocessor controlled the stepper motor to achieve directional intermittent stop and realize accurate alignment of the jujube in the jujube pit removing area. The inserted rods were launched and completed the jujube pit removing promptly in the transitory pause. Dried jujube pits were carried unceasingly by the roller conveyor chain and output directly. The whole operating circle of the automatic jujube pit removing was completed. The dried jujubes used in the test were those whose diameter ranged from 20 to 30 mm and longitudinal ranges from 35 to 45 mm. The result showed that the average directional ratio was 98.3%, the jujube pit removing rate was at least 93.75%, and the average crushing rate was 1.46%. In this paper, the automatic feeding jujube pit extractor achieved high efficiency of feeding jujubes one by one, meeting the demand of accurate detection and location. It realized fast and efficient dried jujube pit removing and smooth unloading. According to the test results, the chained pneumatic punching automatic dried jujube pit removing machine adopted the chained roller conveying mechanism to realize the automatic orientation and feeding of the jujubes individually. The elastic bump roller which fitted the size, shape and other characteristics of the dried jujube reduced the central height error of different sizes. The image detection working with the upper and lower roller clamping device was controlled by the embedded microchip to achieve high precision of locating and reduce the probability of the invalid jujube pit removing operation at the same time. The whole machine realized the purpose of automatic feeding, accurate location and effective jujube pit removing.
