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Composting is an effective management practice for converting animal waste to a valuable soil amendment that has the potential to reduce pollution. Rectangular bed composting with daily turning is widely used in China, but gas emission from this method has not be reported. The goals of this study were to evaluate seasonal differences in greenhouse gas (GHG) emissions and the relative contributions of the GHGs from a commercial swine manure composting facility with daily turning. The compost mixture of swine manure and mushroom residues was turned and moved forward 2 m every day, and it took approximately 20 d to move the raw materials from the head side to the end side of the composting bed. The gases were sampled daily with the static chamber method, and gas concentrations were measured with a gas chromatograph. Compost and air temperatures were monitored. The compost was sampled every 3 d for nitrogen and carbon contents. Cumulative emissions in spring, summer, autumn, and winter were 14.1 ±4.0, 24.1 ±2.2, 10.5 ±0.8, and 11.9 ±3.4 kg CO2 m-2, respectively; 311 ±106, 482 ±44, 113 ±9, and 105 ±21 g CH4 m-2, respectively; and 2.1 ±0.3, 2.7 ±0.4, 0.5 ±0.2, and 1.3 ±0.4 g N2O m-2, respectively. Averaged over the four seasons, greenhouse gas flux was 12.38 ±8.90 g CH4 m-2 d-1 and 0.083 ±0.048 g N2O m-2 d-1. The reason for the lowest emission in autumn was unclear. Excluding CO2, methane contributed approximately 87.5% to 94.9% of the CO2e emissions, whereas N2O contributed the rest. Because the static chamber did not capture emissions during turning, it is recommended that more robust methods (such as dynamic plume or mega dynamic chamber) should be applied to measure the emissions for inventory studies. The high temperatures in the last few days indicated that composting was still ongoing and the duration should be increased. [ABSTRACT FROM AUTHOR]

Anaerobically digested swine wastewater has high concentrations of total ammoniacal nitrogen (TAN) (approximately 1,000 mg N L-1) and a low chemical oxygen demand (COD) to total nitrogen (TN) (COD/TN) ratio of <3.0, making it difficult to achieve a high TN removal rate using traditional biological nitrogen removal processes. The purpose of this study was to investigate the effectiveness of combining ammonia stripping (AS) and membrane bioreactor (MBR) processes to remove nitrogen from anaerobically digested swine wastewater. The coupling parameters that would lead to a high TN removal rate and cost effectiveness were also explored. Ammonia stripping was conducted at two pH levels of 10.0-10.5 (High-pH) and 9.0-9.5 (Low-pH). The MBR had the configuration of anoxic biofilm and aerobic MBR, and it was operated at two influent COD/TN ratios of 6.0-8.0 and 5.0-6.0 coupled with two TAN sludge loading rates in the oxic zone of 0.04-0.05 and 0.12-0.16 kg N kg-1 mixed liquid suspended solid (MLSS) d-1. Total nitrogen removal rate for the High-pH and Low-pH AS was 83% and 65%, respectively. In the MBR at a dissolved oxygen (DO) level of 6.12 -0.69 mg L-1, increasing the TAN sludge loading rate from 0.04 to 0.16 kg N kg-1 MLSS d-1 led to an increase in free ammonia from 0 to 4-9 mg L-1 and an increase in nitrite accumulation rate (NAR) from 0% to 71%. At a TAN sludge loading rate in the oxic zone of 0.12 kg N kg-1 MLSS d-1 and NAR of 53%, the TN removal rate reached 82% in the MBR through shortcut nitrification and denitrification (SND). The influent biochemical oxygen demand (BOD5) to TN (BOD5/TN) ratio was 1.41, COD/TN was 5.41, and the oxidation-reduction potential (ORP) of the denitrification zone was as low as -300 to -400 mV. Among the experimental conditions examined, the combined Low-pH AS+SND process provided the highest TN removal rate of 94% with the least cost and HRT. [ABSTRACT FROM AUTHOR]

Methods are needed to estimate R-factor values and their seasonal distribution from daily rainfall totals in regions with little or no sub-daily rainfall intensity data. This study used calculated R-factor values for a 29-year period (1956-1984) for 22 locations in mainland China to evaluate two estimators of rainfall erosivity for large-scale application of the Universal Soil Loss Equation (USLE) or the Revised USLE (RUSLE), one for an R-factor estimated from mean annual precipitation and another for event erosivity from daily rainfall. This study shows that as a first approximation, the mean annual precipitation is non-linearly related to the R-factor, and that the relationship can be used to predict the R-factor for mainland China locations (Nash-Sutcliffe model efficiency Ec = 0.88, RMSE = 28% of the mean). The nonlinear relationship for China is quite similar to those reported in other studies for Australia and the U.S. The study also shows that a daily rainfall erosivity model using average parameter values previously applied for Australia can satisfactorily estimate the seasonal variation in rainfall erosivity in addition to the R-factor for the mainland China locations (Ec = 0.90, RMSE = 25% of the mean). Once calibrated, model estimates of the R-factor and its monthly distribution from daily rainfall for the mainland China locations improved noticeably (Ec = 0.99, RMSE < 10% of the mean). The daily rainfall erosivity model and a gridded daily precipitation dataset (the China Gridded Daily Precipitation Product) with a 0.25° (~25 km) resolution were then used to produce a concurrent daily rainfall erosivity map for the mainland China locations (Ec = 0.96, RMSE = ~23% of the mean) for a 5-year period from April 2008 to March 2013. This study shows that: (1) mean annual precipitation can be used to estimate the R-factor for mainland China, Australia, and the U.S.; and (2) a calibrated daily rainfall erosivity model performed well in estimating the seasonal and interannual variations in rainfall erosivity, in addition to the R-factor, for large-scale erosion monitoring and assessments in China. [ABSTRACT FROM AUTHOR]

The effect of ventilation rate (VR) on ammonia and greenhouse gas emissions from co-composting dead hens mixed with hen manure was quantified. Three VR levels of 0.9, 0.7, and 0.5 m³ h-1 were evaluated. Gaseous concentrations were measured using a multi-gas infrared photoacoustic analyzer, VR was measured with flowmeters, and the gas emission rate was computed from the VR and gas concentration. Decomposition of the carcasses over the 11-week composting period was greater than 88%. VR was found to significantly affect NH3, CO2, and CH4 emissions (p < 0.05). Specifically, cumulative emissions per kg of initial matter for VR of 0.9, 0.7, and 0.5 m³ h-1 were, respectively, 2.4, 2.0, and 1.2 g NH3; 78, 66, and 42 g CO2; 120, 90, and 52 mg CH4; and 6.4, 6.1, and 5.1 mg N2O. Hence, the study results suggest that the ventilation rate can be adjusted to reduce NH3 and GHG emissions from animal mortality compositing. [ABSTRACT FROM AUTHOR]

This study quantifies concentrations and emission rates (ER) of ammonia (NH3) and greenhouse gases (GHG), including carbon dioxide (CO2) and methane (CH4), during four seasons of one year in north China from a naturally ventilated dairy cattle barn with a daily manure collection system, with each monitoring episode lasting five consecutive days. Gaseous concentrations of background and exhaust air were measured using an infrared photoacoustic multi-gas monitor with a multi-channel sampler. About 120 gas concentration measurements were taken for each season. Barn ventilation rate (VR) was determined by CO2 mass balance using literature metabolic rate data for dairy cattle. Both gas concentrations and ER showed considerable diurnal and seasonal variations. Annual mean (±SD) ER of NH3, CO2, and CH4 for the monitored dairy cattle barn were 75.5 ±253 g d-1 cow-1, 8.9 +0.7 kg d-1 cow-1, and 305 ±119 g d-1 cow-1, respectively. Ammonia and greenhouse gas ERfrom the current study were within the ranges of values reported for dairy cattle. [ABSTRACT FROM AUTHOR]

This study quantifies concentrations and emission rates (ER) of ammonia (NH3) and greenhouse gases (GHG) including carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) from a naturally ventilated cage layer (Hy-Line brown strain) house with daily manure removal, located in northeast China during four seasons of one year, with each monitoring episode lasting five consecutive days. Gaseous concentrations of background and exhaust air were measured using an infrared photoacoustic multi-gas monitor with a multi-channel sampler. Building ventilation rate (VR) was determined by CO2 mass balance using literature metabolic rate data for modern laying hens. Both gas concentrations and ER showed considerable diurnal and seasonal variations. Annual mean (±SD) ER of NH3, CO2, CH4, and N2O for the monitored layer house were, in mg d-1 bird-1, 129 ±40.3, 78,250 ±15,384, 112 ±56.5, and 9.4 ±2.5, respectively, or in g d-1 AU-1 (AU = 500 kg live body weight), 33.4 ±11.4, 19,975 ±3,071, 29.2 ±15.2, and 2.5 ±0.7, respectively. Ammonia ER from the current study was within the ranges of values reported for high-rise houses with annual manure removal and manure-belt houses with daily manure removal. Results of the study contribute to improving ammonia and GHG emissions inventory for animal feeding operations in China and worldwide. [ABSTRACT FROM AUTHOR]

This article presents the development of a two-tractor platooning system on sloping terrain. A reference course for the following tractor was dynamically created from the position points of the leading tractor and subsequently processed by the least squares fitting method to filter out some noise. A path-tracking controller composed of the feedforward and feedback component elements was employed to guide the following tractor along the reference course. Field tests were conducted on an 11° sloping meadow. The results indicated that the following tractor tracked the leading one successfully, with mean and RMS lateral deviations of less than 0.028 and 0.078 m, respectively, at travel speed of 0.5 m s-1 on sloping terrain. [ABSTRACT FROM AUTHOR]

Gas analyzers are commonly protected from impurities in air sampling via use of in-line dust filters to ensure operational performance and longevity of the instruments. This is especially true with extended periods of air quality monitoring in dusty environments. Prices for commercially available filters and monitoring needs vary considerably. A question that has often come up but has not received much investigation is how the filter media types (e.g., paper vs. Teflon) and operational conditions (clean vs. dirty) impact the integrity of gaseous concentration measurement. The study reported here was conducted toward addressing this issue. Specifically, the study assessed the magnitude of ammonia (NH3) adsorption for several types of in-line filters and conditions often used or encountered in animal feeding operation air emission studies, namely, Teflon (most expensive), paper (least expensive), and stand-alone automobile fuel filters, being either clean (new) or dust-laden. Three nominal NH3 levels (20, 45, or 90 ppm, generated with poultry manure) coupled with two nominal airflow rates (4 vs. 8 L/min or 8 vs. 16 L/min) through the filters were used in the evaluation. The types of dust used in the study included corn starch and broiler-house dust. Simultaneous measurements of NH3 concentrations before and after the tested filter were made with two photoacoustic gas spectrometers. The results revealed that NH3 adsorption was highest for the fuel filter initially but negligible for the Teflon filters. However, after 30 min exposure, relative NH3 adsorption by the filters mostly fell below 1%. The higher flow rate led to significantly lower relative NH3 adsorption for both the fuel and paper filters (P < 0.001) but made no difference for the Teflon filters (P = 0.31 to 0.49). During fresh-air purging of the fuel filters laden with broiler-house dust, NH3 was initially released but diminished after 15 min. The results suggest that when used properly (e.g., proper flow rate), the in-line dust filters tested in this study (fuel, paper, and Teflon) offer viable, performance-based options for air emissions (especially NH3) measurement applications. [ABSTRACT FROM AUTHOR]

Emissions of greenhouse gases (GHGs) from animal feeding operations to the atmosphere are of environmental importance and concerns because of their impact on global warming. Gaseous concentrations and emission rates (ERs) of animal facilities can be affected by the animal production stages, animal species, dietary nutrition, housing types, manure handling schemes, and environmental conditions. This article reports ERs of methane (CH4), nitrous oxide (N2O), and carbon dioxide (CO2) for a typical, naturally ventilated 24-crate swine farrowing barn located in suburban Beijing, China, that was monitored over one-year period. The measurements were made at bi-monthly intervals (i.e., six measurement episodes total), with each measurement episode covering three consecutive days. Gaseous concentrations were monitored at bi-hourly intervals throughout each 3-day measurement episode. The ventilation rate of the barn was estimated using the CO2 mass balance method. The GHG concentrations and ERs of the farrowing barn showed diurnal and seasonal variations. Specifically, the concentrations (monthly mean ± SD, mg m-3) ranged from 2.3 (±0.3) to 9.3 (±2) for CH4, from 0.6 (±0.02) to 1.2 (±0.16) for N2O, and from 1, 370 (±163) to 11,100 (±950) for CO2, with the higher levels occurring in January and the lower levels in July. The specific ER ranged from 95.2 to 261.8 mg h-1 pig-1 for CH4, from 6.4 to 12.9 mg h-1 pig-1 for N2O, and from 122.9 to 127.3 g h-1 pig-1 for CO2 . On the basis of per animal unit (1 AU = 500 kg live body mass), the average daily ERs of the farrowing barn were 9.6 ± 3.6 g AU-1 d-1 for CH4, 0.54 ± 0.15 g AU-1 d-1 for N2O, and 7.5±0.1 kg AU-1 d-1 for CO-2. Results of the GHG ERs from this study differ markedly from the limited literature data collected primarily under European production systems and conditions. Results of the current study provide some baseline data on GHG ERs for swine farrowing operations, thus contributing to development or improvement of GHG emission inventory under the Chinese livestock production conditions. [ABSTRACT FROM AUTHOR]

Carbonaceous and nitrogenous gases are produced during storage of livestock manure, with the magnitude of production being affected by the chemical properties of the manure and the physical conditions of storage. This lab-scale study quantifies the emission rates of ammonia (NH3), nitric oxide (NO), and greenhouse gases (GHG), i.e., methane (CH4), carbon dioxide (CO2), nitrous oxide (N2O), from biogas digester effluent (BDE) stored at different depths of 1.0, 1.5, and 2.0 m in dynamic emission vessels (DEVs). The selected storage depths were reflective of the typical depth range of on-farm BDE storage in China. The static storage was held at a relatively constant media temperature of 15°C and an air exchange rate of 11.5 air changes per hour (ACH) for 78 days. Each depth regimen was replicated four times using four DEVs (12 DEVs total). The results showed that the mean (±SE) daily gaseous emission rates per volume of BDE stored at 1.0, 1.5, and 2.0 m depths, in g gas m-3 d-1, were, respectively, 9.1 (±0.7), 10.1 (±0.6), and 10.1 (±0.4) for CH4 (p = 0.39); 38.0 (±2.2), 34.5 (±1.3), and 30.7 (±0.6) for CO2 (p < 0.05); 1.9 (±0.11), 1.3 (±0.08), and 0.9 (±0.03) for NH3 (p < 0.05); and 6.7 (±0.5) x 10-3, 5.0 (±0.8) x 10-3, and 3.4 (±0.2) x 10-3 for N2O (p < 0.05). Nitric oxide (NO) emissions were negligible. The overall GHG (CH4 + N2O + CO2) emissions were dominated by CH4, which accounted for more than 85% of the CO2-equivalent emissions for all three storage depths. The CH4 emissions peaked during the early storage period, with the first 20-day cumulative emissions accounting for 56% to 58% of the total 78-day storage emissions. The results reveal that storage of BDE at 2.0 m depth yielded lower CO2, NH3, and N2O emission rates but similar CH4 emission rates compared to the 1.0 and 1.5 m depths. [ABSTRACT FROM AUTHOR]

Biogas digesters are commonly used in livestock farming in China. The digestion process converts large amounts of raw liquid manure (RLM) to biogas digester effluent (BDE). The BDE is then stored on the farm for some time before land application as crop or orchard nutrients. Storage of RLM or BDE is associated with gas emissions, although little information is available concerning comparison of air emissions between the two handling practices. This study was conducted to compare methane (CH4), carbon dioxide (CO2), nitrous oxide (N2O), and ammonia (NH3) emissions from RLM and BDE storages using dynamic emission vessels (DEVs). Both media were stored in closed vessels (50 L) at a 40 cm storage depth, a constant storage temperature of 30°C, and a headspace air exchange rate of 15 to 17 air changes per hour (ACH) for 22 days. The results showed that the average daily gas emission rates for RLM and BDE, in mg L-1 d-1, were, respectively, 102.9 and 125.3 CO2 (p < 0.05), 0.72 and 3.33 N2O (p < 0.05), 29.2 and 0.32 CH4 (p < 0.05), and 1.21 and 0.66 NH3 (p = 0.08). The total greenhouse gas (GHG = CH4 + CO2 + N2O) emissions were similar for RLM and BDE, 1.05 and 1.12 g CO2-eq L-1 d-1, respectively (p = 0.26). Nitrous oxide (N2O) emissions accounted for 88.2% of the CO2-eq GHG emissions for BDE, whereas CH4 emissions accounted for 69.7% of the CO2-eq GHG emissions for RLM. The high N2O emissions from BDE likely resulted from the lower COD/N ratio in BDE than RLM under the storage conditions. Differences in gaseous emission characteristics between RLM and BDE were attributed to the differences in methanogen species and the population of ammonia-oxidizing bacteria (AOB). [ABSTRACT FROM AUTHOR]

This study was conducted to evaluate the effects of dietary forage type and concentrate-to-forage ratio (CTFR) on CH4 emissions from dairy cows in China using the SF6 tracer method Rumen fluid concentrations of NH4-N and VFA, rumen fluid pH, and daily milk yield were measured as well The dietary regimens included: corn stalks (dry corn stalks after corn harvest) as the forage source at CTFR of 40:60 (ration A), corn silage as the forage source at CTFR of 40:60 (ration B), and corn silage as the forage source at CTFR of 60:40 (ration C). Twelve dairy cows (body weight = 525 ±12 kg, mean ± SE) were divided into three groups of four animals each, balanced in age and body weight, and randomly allocated to the dietary treatments. The study was run for 25 days, with the first 15 days used for adjustment and the subsequent 10 days used for response measurement. The dietary treatments ranked ration A > ration B > ration C for CH4 emissions quantity (L d-1 head-1 ), rumen fluid pH, acetic acid concentration, and ratio of acetic acid and propionic acid concentration. For example, CH4 emissions (mean ±SE) for rations A, B, and C were 353±13.4, 283±7.48, and 263 ±9.04 L d-1 head -1, respectively, or 335 ±12.75, 270 ± 7.12, and 250 ± 8.6 L d-1 AU-1 (AU = 500 kg live weight). On the other hand, the treatments ranked ration A < ration B < ration C for concentrations of NH3-N, propionic acid, and butyric acid in the tureen fluid This study indicates that CH4 emissions intensity from dairy cows (g kg-1 milk output) can be significantly reduced by using corn silage as a forage source and by increasing the content of concentrates in the ration. Compared with rations B and C, ration A increased CH4 emissions by 25% and 34% (p < 0.01), respectively. A full assessment of the effectiveness of such an improved feeding management, through life cycle analysis, in reducing carbon footprint would be warranted in future studies. [ABSTRACT FROM AUTHOR]

Hoop structures have been used quite widely for animal production in the U.S. due to their lower capital costs and multi-purpose versatility. Hoop barns for grower-finisher (G-F) swine production have attracted attention in China as an alternative, environmentally friendly, and water-saving production system. This study was conducted to assess concentrations and emissions of ammonia (NH3) and greenhouse gases (GHGs) for a hoop G-F pig barn at a commercial pig operation in suburban Beijing, China. The NH3 and GHG concentrations and emissions of the facility were measured for three consecutive days during spring and summer seasons. The results revealed the following hourly gaseous concentrations (mean ± SD, mg m-3): 5.9 ± 2.7 NH3, 2,183 ± 1,376 CO2, and 4.0 ± 2.5 CH4 in spring, and 6.8 ± 3.4 NH3, 1,530 ± 364 CO2, and 5.0 ± 2.3 CH4 in summer. The estimated gaseous emissions averaged, in g pig-1 d-1, 22.7 NH3, 2,003 CO2, and 6.7 CH4, or in g AU-1 d-1 (AU = 500 kg), 124 NH3, 11,264 CO2, and 36.2 CH4. The emission values from this study, while being generally comparable with those reported in the literature, add new information concerning emissions from alternative swine housing system. [ABSTRACT FROM AUTHOR]

Membrane concentration processes have been used to treat anaerobically digested (AD) slurry for nutrient recovery and pollutant removal; however, these methods often face the challenges of low processing stability and efficiency. In this study, the performance (processing stability and efficiency) of three membrane concentration processes, including nanofiltration (NF), reverse osmosis (RO1) and two-stage NF-RO (NF-RO2), in treating ceramic membrane-pretreated swine manure AD slurry was evaluated and compared. Nutrient and antibiotic redistribution in the concentrate and permeate was also investigated. Results show that NF-RO2 had higher processing stability and efficiency than the other two processes. High nutrient recoveries of 61.9% for total nitrogen, 56.3% for total phosphorus, and 67.0% for potassium in the concentrates were observed in NF-RO2. The removal rates for antibiotics sulfamethazine and oxytetracycline in NF-RO2 were 99.3% and 81.9%, respectively. Therefore, NF-RO is an effective way to recover nutrients and remove pollutants from AD slurry. [ABSTRACT FROM AUTHOR]

In the design of agricultural machinery, the lack of systematic and structured knowledge utilization systems results in low development efficiency and poor reusability of design knowledge. This study considers the design of a combine chassis and focuses on the application of knowledge-based rapid design to agricultural machinery. As a typical sophisticated agricultural machine, combines have a complicated design that requires the integration of multiple disciplines according to the crop types, production areas, and ability of the designers. Hence, a knowledge-based design system for a wheeled combine chassis is proposed. By integrating object-oriented technology with a mixed reasoning strategy, multisource heterogeneous design knowledge can be applied in completing the chassis design task. To date, there are more than 2000 design ideas and 350 parameter models in the knowledge database. In addition, tacit design knowledge acquired by a knowledge discovery method can be employed to perfect the design and improve the reliability of the product. The design of a combine chassis demonstrates that the knowledge-based rapid design of agricultural machinery is completely feasible, and the design system significantly reduces the design workload, shortens the development cycle, and improves design efficiency and knowledge utilization. [ABSTRACT FROM AUTHOR]

China raises 50% of global live pigs. However, few studies on the carbon footprint (CF) of large-scale pig production based on China's actual production conditions have been carried out. In this study, life cycle assessment (LCA) and actual production data of a typical large-scale pig farm in northern China were used to assess the greenhouse gas (GHG) emissions or CF associated with the whole process of pig production, including feed production (crop planting, feed processing, and transportation), enteric fermentation, manure management, and energy consumption. The results showed a CF of 3.39 kg CO2-eq per kg of live market pig and relative contributions of 55%, 28%, 13%, and 4% to the total CF by feed production, manure management, farm energy consumption, and enteric fermentation, respectively. Crop planting accounted for 66% of the feed production CF, while feed processing and transportation accounted for the remaining 34%. Long-distance transport of semi-raw feed materials caused by planting-feeding separation and over-fertilization in feed crop planting were two main reasons for the largest contribution of GHG emissions from feed production to the total CF. The CF from nitrogen fertilizer application accounted for 33% to 44% of crop planting and contributed to 16% of the total CF. The CF from the transport of feed ingredients accounted for 17% of the total CF. If the amount of nitrogen fertilizer used for producing the main feed ingredients is reduced from 209 kg hm-2 (for corn) and 216 kg hm-2 (for wheat) to 140 kg hm-2 (corn) and 180 kg hm-2 (wheat), the total CF would be reduced by 7%. If the transport distance for feed materials decreased from 325 to 493 km to 30 km, along with reducing the number of empty vehicles for transport, the total CF would be reduced by 18%. The combined CF mitigation potential for over-fertilization and transport distance is 26%. In addition, the use of pit storage, anaerobic digestion, and lagoon for manure management can reduce GHG emissions from manure management by 76% as compared to the traditional practice of pit storage and lagoon. This case study reveals the impact of planting-feeding separation and over-fertilization on the CF of the pig supply chain in China. The manure management practice of pit storage, anaerobic digestion, and lagoon is much more conductive to reducing the CF as compared to the traditional practice of pit storage and lagoon. [ABSTRACT FROM AUTHOR]

With the rapid growth of large-scale and intensive swine farms have come many ecological and environmental problems associated with the substantially increased and concentrated animal waste production. In this article, a swine manure and flushed slurry to renewable energy management system is present and discussed. This system was installed in a commercial feeder-to-finish swine farm with 18,000 head of swine in Beijing, China, and included two mesophilic upflow solids reactors (USRI and USRII, 500 m3 and 700 m3) and one psychrophilic plug-flow reactor (PFR, 1000 m3). In this study, USRII was monitored throughout a whole year to evaluate the performance of this swine waste to energy system. The biogas plant used mixed solid swine manure and flushed slurry as substrate with a relatively low organic loading rate (OLR) of 0.7 to 1.8 kg volatile solids (VS) m-3 d-1. The hydraulic retention time (HRT) varied from 15 to 22 days depending on the season. Less added water contributed to the longer HRT and more concentrated influent in winter. In winter, the specific methane production (SMP) of the digester was 0.43 m3 CH4 kg-1 VSadded, which was slightly lower than the value reported in Europe (0.45 m3 CH4 kg-1 VSadded) but about 48.3% higher than that in Asia (0.29 m³ CH4 kg-1 VSadded). This indicated that the performance of this USR in winter was stable, with a higher biogas production, and up to 90% of the VS was removed as well. However, the low OLR limited the volumetric methane production rate to only 0.21 to 0.57 m³ m-3 d-1. [ABSTRACT FROM AUTHOR]

Intra-storm temporal distributions of precipitation are important for infiltration, runoff, and erosion process understanding and models. A convenient and established method for characterizing precipitation hyetographs is the use of non-dimensional Huff curves. In this study, 11,801 erosive rainfall events with 1 min resolution data collected over 30 to 40 years from 18 weather stations located across the central and eastern parts of China were analyzed to produce Huff curves. Each event was classified according to the quartile period within the event that contained the greatest fraction of rainfall. The results showed that 38.3% of events had the maximum rainfall amounts in the first quartile, followed by the second (26.8%), third (22.4%), and fourth (12.5%) quartiles. Quartile I and II events were generally characteristic of shorter duration and heavier intensity events. Quartile I events averaged 23% shorter durations than quartile IV events, whereas the mean intensity (Iavg), mean maximum 30 min intensity (I30), and mean rainfall erosivity index (EI30) were 1.71, 1.22, and 1.23 times greater, respectively, than those for quartile IV and were significant at a 5% level based on two-sample t-tests. The proportion of quartile I events was less for events of longer duration, whereas the proportions of quartile III and IV events were greater. Two-sample Kolmogorov-Smirnov tests suggested that regional Huff curves can be derived for the central and eastern parts of China. Regional Huff curves developed in this study exhibited dissimilarities in terms of the percentages of storms for different quartiles and the shapes of the curves compared to those reported for Illinois, peninsular Malaysia, and Santa Catarina in Brazil. [ABSTRACT FROM AUTHOR]

Ammonia (NH3) emissions from laying hens are affected by nutrient content of the diet, manure quantity, and manure properties such as moisture content, nitrogen content, and pH. These production traits may vary with strain of the hen. However, limited information is available concerning the effects of laying-hen genetics on manure properties and NH3 emission. This study was conducted to comparatively quantify production performance, manure properties, and NH3 emissions (through N mass balance) of four white-egg-laying strains (Hy-Line W-36, Hy-Line W-98, Lohmann LSL Lite, and Bovans White) and four brown-egg-laying strains (Hy-Line Brown, Lohmann Brown, ISA Brown, and Bovans Brown) during two production periods of 27-28 weeks (PI) and 35-36 weeks (P2) of age. The diets were formulated to meet the nutritional needs of the brown and white hens. As a result, crude protein contents during PI and P2 were, respectively, 13.2% and 15.2% for the brown hens but 14.5% and 17.4% for the white hens. The results showed that the brown and white hens had similar hen-day egg production (97.5% to 89.2% for brown hens and 96.0% to 88.2% for white hens) and egg mass output (57.1 to 52.6 g d-1 hen-1 for brown hens and 55.6 to 51.2 g d-1 hen-1 for white hens) but different feed consumption (112 to 98 g d-1 hen-1 for brown hens and 101 to 93 g d-1 hen-1 for white hens, p < 0.01) and feed efficiency (1.97 to 1.87 g feed g-1 egg for brown hens and 1.82 g feed g-1 egg for white hens, p < 0.0001 and p = 0.11). The higher feed consumption for the brown hens stemmed from their heavier body mass (1.81 to 1.78 kg vs. 1.56 to 1.53 kg for white hens). Manure moisture content was higher for the brown hens than for the white hens, although the dry-matter manure production was not significantly different. The results further revealed that under the experimental conditions (i.e., higher CP contents of the diet for the white hens than for the brown hens) the white hens had higher NH3 emissions than the brown hens as expressed per hen (37% to 19% higher, p = <0.001 to 0.016), per animal unit (AU, 500 kg live body mass; 59% to 39% higher, p = 0.0007 to 0.007), per unit of egg mass output (41% to 24% higher, p = 0.01 to 0.09), per unit of feed N consumed (39% to 27% higher, p = 0.01 to <0.0001), and per unit of dry manure (56% to 39% higher, p = 0.001 to 0.007). Certain differences existed in production performance among strains within the brown or white hens, but no differences in NH3 emissions were detected. Because of the relatively small sample size (number of hens involved) and the relatively short monitoring period, the results should be referenced with these limitations in mind. Further larger-scale studies with longer monitoring periods to verify these findings are warranted. [ABSTRACT FROM AUTHOR]