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Guangdong Province is one of the largest agricultural regions in China, in addition to the robust economy. Agricultural development has been accelerated to ensure the food security in recent years. The agricultural non-point source pollution has been triggered by the large-scale investments in chemical fertilizers, pesticides, plastic mulch, and the rapid development of the livestock and poultry breeding industry. The purpose of this study is to unveil the emission quantity and sources of agricultural non-point source pollutants in Guangdong Province, elucidate the main characteristics and development trends of agricultural non-point source pollution, and thereby propose control measures targeting the primary pollutant sources. In this study, the emission coefficient was proposed to estimate the number of various pollutants that emitted by agriculture, livestock and poultry breeding, and aquaculture in Guangdong Province of China from 1991 to 2021. The data was also collected to better understand the agricultural development in the fertilization, arable land area, pig, cattle, poultry and aquaculture. The main causes were then determined for the agricultural non-point source pollution and their changing trends over time. The results show that: 1) An upward trend was found in the total discharges of chemical oxygen demand (COD), ammonia nitrogen (NH3 -N), total nitrogen (TN), and total phosphorus (TP) from the agricultural sources. The discharges of various pollutants decreased slightly since 2018, due to the reducing use of chemical fertilizer. The amount of fertilizer was applied per unit area more than twice the international average level. It is very necessary to reduce the chemical fertilizer use for the high efficiency. The discharges of COD, NH3 -N, TN, and TP from the agricultural sources increased to 1.9, 1.9, 1.7, and 2.2 times, respectively, in 2021, compared with 1991. 2) The primary contributors to the agricultural non-point source pollution were the planting, livestock and poultry breeding industries. The planting industry was contributed the most to the nitrogen discharges, accounting for 48% of NH3 -N losses, and 52% of total nitrogen losses from the agricultural sources, respectively. In addition, the water pollution that caused by the planting industry was mainly from the application of chemical fertilizers. The livestock and poultry breeding industry was the primary source of COD and TP discharge from the agricultural sources. Specifically, 90% and 51% of the total COD and TP discharges from agricultural sources were from the livestock and poultry breeding sector, respectively. The number of pollutants that discharged by the large-scale farming were accounted for more than 70% of the total pollutants discharged by the livestock and poultry breeding industry. Among different types of livestock and poultry, pigs were contributed the most to the emission of various pollutants, followed by poultry. Different pollutants that emitted by the aquaculture industry were accounted for between 10% and 16% of total emissions from agricultural sources. Aquaculture was ever increasing every year. Moreover, the effluent that produced by aquaculture (particularly mariculture) was challenging to clean up. Consequently, the number of pollutants that discharged into water from aquaculture sources will increase over time, indicating the increasing share of the total emissions from agricultural sources. Therefore, it is urgent to find the solutions for the waste disposal of large-scale pig farms. Also, the pollutant discharges from aquaculture needs to be considered. The finding can also provide a strong reference for the decision-making in the agricultural environment. [ABSTRACT FROM AUTHOR]

The pigeon industry is emerging after the "three birds" in the special poultry breeding. Pigeon breeding has also been well developed over more than 30 years in the animal husbandry industry in China. In this study, an improved RetinaNet model was proposed for the individual detection of caged pigeons during the breeding period. An accurate and rapid individual detection in the cage was realized to improve the breeding efficiency. The original image dataset was first collected in the Golden Green Pigeon Breeding Base in Xingning, Guangdong Province, China. The images were then enhanced by the vertically flipped, adding noise, and brightness. As such, the training and validation datasets were expanded to five times the original images. A total of 5 420 pigeon images were selected to be labeled, where 5 190 images were set as the training and validation set, and 230 as the test set. The model was improved using the RetinaNet. The Convolutional Block Attention Module (CBAM) was introduced before the classification and regression sub-networks. As such, the information of the feature map was enhanced for the better model. Two backbone networks (ResNet50 and ResNext50) were selected to compare to the Feature Pyramid Networks (FPN) with different layers on the individual detection of pigeons in the breeding period. 11 experiments were then performed on the same training, validation, and test set under the operating system of Ubuntu18.04 and graphics card: NVIDIA TITAN RTX. The commonly-used SSD and YOLOv3 in the one-stage object detection were selected to compare with the RetinaNet model framework in this case. Eight experiments were also carried out to optimize the model using the same dataset and training parameters. The results showed that the mAP of the original RetinaNet model structure was 65.44%, which was 3.21, 13.7, 4.47, 6.24, and 3.54 percentage points higher than that of SSD, YOLOv3, YOLOv4, YOLOv5s, and YOLOv5m, respectively. The overall detection effect of the original RetinaNet model was better than that of SSD and YOLOv3. Moreover, the number of FPN layers increased the detection scale, thereby effectively improving the recall of small objects. The missed detection of pigeon eggs was also reduced in the actual breeding environment using the original RetinaNet. Meanwhile, the CBAM was introduced before the classification and regression sub-network, in order to promote the detection effect on the adhesion pigeons. The improved RetinaNet model presented an average accuracy of 95.88%, 79.51%, and 67.29% on the test set of pigeons, squabs, and pigeon eggs, respectively, which were 2.16, 21.74, and 22.48 percentage points higher than the original RetinaNet model. There was also much more improvement in the average precision of adhesive squab and small pigeon eggs. Consequently, the improved model can also be expected to present the best performance. The real-time monitoring of individual changes can be achieved in the pigeon cage. The finding can provide the technical support for precision breeding, in order to timely detect and adjust the improper behavior of production management. [ABSTRACT FROM AUTHOR]

Manure slurry is a mixture of urine, feces, flushing water, and disinfectant in the livestock and poultry breeding industry. About two billion tons of manure slurry can be produced in China every year. Among them, the composition varies greatly, due to the complex sources. There are many influencing factors on the composition of manure slurry, such as the seasons, regions, breeding scale, fecal cleaning, and manure slurry treatment. Currently, the fixed composition value cannot accurately be calculated the amount of manure slurry, when returning to the field. Therefore, it is urgent to develop an accurate, and rapid detection system suitable for the compositions in the manure slurry on site. Fortunately, Near-Infrared (NIR) spectroscopy can offer a great potential to detect manure composition at present. Nevertheless, most reports were usually focused on the near-infrared spectrometer at the large-scale laboratory level. This kind of instrument can be confined to the application of near-infrared spectroscopy analysis in fields, due to the large bulk volume, low portability, and high price. The near-infrared spectrometer can be further developed towards the miniaturization for the technical and cost feasibility during on-site detection, particularly with the development of Micro-Electromechanical Systems (MEMS) and Micro-Opto-Electro-Mechanical Systems (MOEMS) in recent years. In addition to the need for a stable and reliable hardware system, the calibration model is another important application premise of near-infrared technology. But, there is a great challenge to establish the calibration model using cloud sharing technology. It is very necessary to access the shared resources via the various data computing services anytime, anywhere, and on-demand through the Internet. In this study, a micro NIR onsite and rapid system was proposed to detect the composition of manure slurry during field return using a calibration model under cloud sharing. A complete function was also achieved for the data acquisition, upload, prediction and storage at the same time, according to the design scheme of "micro NIR sensor + calibration model cloud sharing + Android client + mobile network". The micro NIR sensor was first used to collect the spectral data of the measured sample, then to transmit the data into the Android client through the Bluetooth protocol, and finally to the cloud server through the mobile network. A calibration model was deployed in the cloud server to calculate the received spectral data. A quantitative prediction was obtained to further send back to the Android client in real time. A rapid detection was realized for the ten parameters of manure slurry compositions, such as the Total Nitrogen (TN), Total Phosphorus (TP), Total Potassium (TK), ammonium nitrogen (NH4 +-N), nitrate nitrogen (NO3 --N), amide nitrogen (CONH2-N), Available Phosphorus (AP), Available Potassium (AK), Organic Matter (OM), and pH value. The prediction relative errors of AK, TN, AP, TP, pH, NH4 +-N, and TK in the manure slurry were less than 10%, and the rest of OM, CONH2-N, and NO3 --N were between 10%-18%. Consequently, the micro NIR technology combined with the calibration model in cloud sharing can be expected to realize the onsite, rapid and accurate detection of various compositions in the manure slurry, particularly for the full sharing of the quantitative model. Moreover, the broad market prospect can be gained for the practical application, due to the portable micro NIR sensor, the simple operation of the Android client, and the lower cost of the system. There is also no need for the professional requirements of the users in the cloud sharing of the calibration model. The finding can provide data support for the high precision return of manure slurry to the field. [ABSTRACT FROM AUTHOR]

A large number of animal manures has been produced in China in recent years, due to the ever-increasing demand for livestock and poultry breeding. Improper disposal can pose potential environmental and health risks. Alternatively, hydrothermal carbonization has been one of the thermochemical technologies to convert the waste biomass into high value-added products without drying raw materials. Therefore, it is a highly promising potential to convert the animal manures into high value-added carbon-rich materials using hydrothermal carbonization, in order to prevent environmental pollution and pathogenic microbe spread from the random accumulation. This review aims to clarify the effects of temperature, liquid-solid ratio, reaction residence time, and additives on the yield and physicochemical properties of hydrochars, according to the main components of animal manures under hydrothermal carbonization. Some mechanisms were evaluated to determine the specific reaction pathways, including hydrolysis, dehydration, decarboxylation, aromatization, Mailard reaction, and polymerization. An interaction was also identified between various factors and reaction kinetics. Among them, the reaction temperature was the most critical factor affecting the reaction pathways and characteristics of products. A mathematical model was then established to describe the hydrothermal carbonization, further evaluating the application effect on laboratory and industrial scale. There was an increase in the temperature and residence time during hydrothermal carbonization, leading to the hydrochar with a higher carbon content and calorific value, but the yield decreased significantly. Furthermore, the volatile content of hydrochar decreased significantly after hydrothermal carbonization, which was related to the reduction of hydroxyl, and carboxyl functional groups. The heavy metals and phosphorus were often fixed in the hydrochars in more stable forms, whereas, nitrogen and potassium were transferred to the liquid products. Medium temperature (180-220 ℃) for a short time (0.5-2 h) was conducive to maintaining the nutrient elements in the hydrochar for the better capacity of soil water holding. Moreover, the hydrochar also varied in the surface functional groups and pore structure, thereby serving as the potential biofuel, adsorbent, soil amendment, and precursor of functional materials. More importantly, the addition of CaO was greatly contributed to the pH and yield of hydrochar in the process of hydrothermal carbonization, together with the improved pore structure and the number of surface functional groups. As such, the acid increased the calorific value, specific surface area, fixed carbon content, and H/C, O/C atomic ratio of hydrochar. Co-hydrothermal carbonization had avoided the weakness of hydrochar produced by a single feedstock with high ash and heavy metals content, which were possibly limited factors for the potential applications in energy materials and soil amendment. Consequently, the porous carbon materials with high specific surface area, excellent pore structure, and adjustable surface chemical properties can be widely expected to prepare in the activation and modification process with the livestock manure hydrochars as a precursor. Microwave-assisted hydrothermal carbonization of animal manures can also realize rapid heating to shorten the reaction time for the higher product yield. A further study needs to be focused on the economic feasibility and large-scale application. This finding can also provide a strong reference to promote the application potential of hydrothermal carbonization in the treatment of animal manures. [ABSTRACT FROM AUTHOR]

The Chinese government has planned to hit the carbon emission peak before 2030 and achieve carbon neutrality by 2060. In this case, it is a high demand to reduce emissions, especially greenhouse gas (GHG) emissions. Among them, the livestock industry has been the greatest GHG emission source in agriculture sectors, accounting for 80% of total agricultural non-carbon dioxide emissions. The Emissions Gap Report 2021 has released that the methane emissions can be reduced from fossil fuels and agricultural wastes, further, slowing down global warming in the shortterm. Therefore, a low-carbon livestock industry can also make a great contribution to achieving the carbon neutrality. In this study, a systematic review was made on the agricultural carbon emissions in China, with emphasis on the sources of GHG emissions in animal production systems. Some suggestions were also proposed to reduce the GHG emissions from the livestock and poultry. The carbon emission of the agriculture sector has been the third-largest source of GHG emissions, accounting for about 6.7% of the total emissions in China. The GHG emissions of animal respiration, ruminant intestinal fermentation, and manure are regarded as the direct sources, whereas, the indirect GHG emissions include feed production and processing, the energy consumption of equipment and facilities, as well as animal product processing and transportation. Enteric fermentation has been the largest source of GHG emissions from livestock, according to the global livestock environmental assessment model. Finally, some technologies were also summarized to reduce the GHG emissions from the livestock and poultry. The low-carbon path contained three parts, the source, the process, and the end, according to the whole life cycle of animal husbandry production. Correspondingly, there was a gradual increase in the indirect GHG emissions via energy consumption during the breeding process of livestock and poultry, particularly with the increase in the production and demand of livestock. Moreover, one of the key strategies is necessary to conduct the financial investment and the national incentive mechanism, thereby achieving carbon neutrality. Therefore, this review can greatly contribute to promoting carbon neutrality for the sustainable development of the livestock industry. Four recommendations were made as follows: 1) To monitor the GHG emissions from the livestock industry throughout the entire process and scientifically evaluate GHG emissions and reduction potential of each link; 2) To strengthen the clean production in animal husbandry, including basic and innovative research, further to promote the animal husbandry in a green, low-carbon, and efficient way; 3) To develop the green and low-carbon utilization of manure resources from the livestock and poultry production; and 4) To integrate the modern information technology for the low-carbon emission reduction in the digitally empowered livestock industry. [ABSTRACT FROM AUTHOR]

The Dongting Lake Plain is one of the most important food production bases in China. However, the non-point source pollution has posed a great threat to social and economic development in the cultivated land, due to a large number of chemical fertilizers and pesticides that have widely been used unreasonably during agricultural production in recent years. It is also very serious for the pollution of livestock and poultry breeding. Taking 21 county-level administrative units in part of Hunan Province in the Dongting Lake Plain as the research area, the inventory analysis was made to construct three types of pollution units for the farmland fertilizer, human and livestock excrement, as well as farmland solid wastes. Some parameters were calculated, including the total emission and intensity of chemical oxygen demand (COD), total nitrogen (TN), and total phosphorus (TP). The temporal and spatial evolution of non-point source pollution was determined in the cultivated land, further to analyze the movement trajectory of emission intensity barycenter and the degree of spatial agglomeration, using the center of gravity model and the cold/hot spot analysis. The results showed that: 1) There was a great decrease in the total emissions and emission intensity of COD, TN, and TP from the cultivated land non-point source pollution in the study area from 2005 to 2019. It was related to the promotion of ecological farming, soil testing formula technology, as well as the scale control of livestock and poultry breeding. There were also the spatial distribution characteristics of "east>west>central" in the pollution degree for three types of pollutants. 2) Three types of pollutants all moved in the longitude and latitude directions, but there was a more obvious in the east-west direction, where the barycenter of emission intensity presented a tendency to run westward. The adjustment and implementation of pollution prevention policies were attributed to the shift of the barycenter of the emission intensity in the three pollutants. 3) There were significant differences in the spatial patterns of the three pollutants. Specifically, the COD pollution was significantly different, TP was followed, and TN was the smallest in various regions. Hot spots were mostly distributed in the east of the Dongting Lake plain around the basin. The main reason was that these areas were on the edges of the intersection of the Dongting Lake and the Yangtze River, with advantageous location, rapid urbanization and industrialization, and stronger arable land utilization. The cold spots were mostly distributed in Nanxian and the surrounding areas in the middle of the Dongting Lake Plain. The concept of ecological civilization was contributed greatly to the distribution. As a result, much attention needs to pay to the treatment of non-point source pollution in the cultivated land and surrounding counties. Consequently, the non-point source pollution was improved in the cultivated land in the process of ecological civilization construction. There was also a great difference in the degree and control of cultivated land non-point source pollution in various regions. The finding can provide a sound theoretical basis to manage the non-point source pollution of cultivated land. [ABSTRACT FROM AUTHOR]