Significant reduction of ammonia emissions while increasing crop yields using the 4R nutrient stewardship in an intensive cropping system

Ammonia (NH_3) emissions should be mitigated to improve environmental quality.Croplands are one of the largest NH_3sources,they must be managed properly to reduce their emissions while achieving the target yields.Herein,we report the NH_3 emissions,crop yield and changes in soil fertility in a long-term trial with various fertilization regimes,to explore whether NH_3 emissions can be significantly reduced using the 4R nutrient stewardship (4Rs),and its interaction with the organic amendments (i.e.,manure and straw) in a wheat–maize rotation.Implementing the 4Rs significantly reduced NH_3 emissions to 6 kg N ha~(–1) yr~(–1) and the emission factor to 1.72%,without compromising grain yield (12.37 Mg ha~(–1) yr~(–1))and soil fertility (soil organic carbon of 7.58 g kg~(–1)) compared to the conventional chemical N management.When using the 4R plus manure,NH_3 emissions (7 kg N ha~(–1) yr~(–1)) and the emission factor (1.74%) were as low as 4Rs,and grain yield and soil organic carbon increased to 14.79 Mg ha~(–1) yr~(–1) and 10.09 g kg~(–1),respectively.Partial manure substitution not only significantly reduced NH_3 emissions but also increased crop yields and improved soil fertility,compared to conventional chemical N management.Straw return exerted a minor effect on NH_3 emissions.These results highlight that 4R plus manure,which couples nitrogen and carbon management can help achieve both high yields and low environmental costs.

Measurement of Ammonia Emission Following Surface Application of Urea Fertilizer from Irrigated Paddy Rice Fields

Ammonia emission is one of the most important pathways of nitrogen loss from agricultural cultivated field. In this paper, we report the measurement of ammonia emission from paddy rice field obtained by surface application of urea fertilizer with water management. The main objective of the present study were to assess the amount of NH3 emission and the loss of nitrogen from paddy field as affected by various N doses, i.e., 0 (control), 90 (N1), 180 (N2), 270 (N3) and 360 (N4) kg ha-1, following field surface application of urea fertilizer with water management. Ammonia emissions were measured by continuous airflow enclosure method from plots fertilized with the application of surface urea. Increase in urea-N dosage increased NH3 emission that was measured from paddy rice field. Ammonia emission started immediately and was almost complete within 12 days after top dressing of urea application to the soils. Ammonia emissions were nearly constant in all treatments from 12 days after fertilizer application. Highest ammonia emission rate was 28 g /day and total amount of ammonia emission was 56.21 kg ha-1 for 360 kg N ha-1 dose. No remarkable observation was found about temperature for ammonia emission. Due to proper water management practices less emission was observed throughout the experiment period. The results also show that N loss through NH3 emission accounted for 11 to 16% during the rice- growing season. These magnitudes of loss of N appear to be most important for environmental point of view.

Improvement in bioconversion efficiency and reduction of ammonia emission by introduction of fruit fermentation broth in a black soldier fly larvae and kitchen waste conversion system

The black soldier fly(BSF),Hermetia illucens(Diptera:Stratiomyidae),is an insect commonly used for the bioconversion of various organic wastes.Not only can the BSF convert organic waste into macromolecular organic substances,such as insect pro-teins,but it can also lessen the pollution associated with these waste products by reducing ammonia emissions,for example.In this study,we measured the effects of adding fruit fermentation broth(Fer)and commercial lactic acid bacteria fermentation broth(Em)to kitchen waste(KW),as deodorizing auxiliary substances,on the growth performance of black soldier fly larvae(BSFL),the intestinal flora structure of BSFL,the ammonia emis-sion from the KW substrate,and the microbial community structure of the KW substrate.We found that the addition of Fer or Em increased the body weight of BSFL after 6 d of culture,increasing the growth rate by 9.96%and 7.96%,respectively.The addition of Fer not only reduced the pH of the KW substrate but also increased the relative abundance of probiotics,such as Lactobacillus,Lysinibacillus,and Vagococcus,which inhibited the growth of ammonifiers such as Bacillus,Oligella,Paenalcaligenes,Paenibacillus,Pseu-dogracilibacillus,and Pseudomonas,resulting in the reduction of ammonia emission in the KW substrate.Moreover,the addition of Fer or Em significantly increased the rela-tive abundances of Bacteroides,Campylobacter,Dysgonomonas,Enterococcus,and Ig-natzschineria in the gut of BSFL and increased the species diversity and richness in the K W substrate.Our findings provide a novel way to improve the conversion rate of organic waste and reduce the environmental pollution caused by BSF.

Research on ammonia emissions characteristics from light-duty gasoline vehicles

In this study,ammonia emissions characteristics of typical light-duty gasoline vehicles were obtained through laboratory vehicle bench test and combined with New European Driving Cycle(NEDC)condition and Worldwide Harmonized Light Vehicles Test Cycle(WLTC)condition.The influence of ambient temperature on ammonia emissions is mainly concentrated in the cold start stage.The influence of ambient temperature on ammonia emission is shown that the ammonia emissions of light-duty gasoline vehicles under ambient temperature conditions(14 and 23℃)are lower than those under low ambient temperature conditions(-7℃)and high ambient temperature conditions(35 and 40℃).The influence of TWC on ammonia emission is shown that ammonia is a by-product of the catalytic reduction reaction of conventional gas pollutants in the exhaust gas in the TWC.Under NEDC operating conditions and WLTC operating conditions,ammonia emissions after the catalyst are 45 times and 72 times that before the catalyst,respectively.In terms of ammonia emissions control strategy research,Pd/Rh combination can reduce NH3 formation more effectively than catalyst with a single Pd formula.Precise control of the engine’s air-fuel ratio and combination with the optimized matched precious metal ratio TWC can effectively reduce ammonia emissions.

Effects of different litters on ammonia emissions from chicken manure

Experiments were conducted to investigate the influences of type of litter,initial moisture content(IMC)of litter,and dry weight ratio of manure to litter(DWRML)on ammonia emissions from chicken manure and the effects of pH values of tea leaves and the mixtures of tea leaves and other litter on the ammonia emissions from chicken manure.For the experiments,four kinds of litter,Northeast pine sawdust(sawdust),rice husk,tea leaves,and wheat straw,were selected.The IMCs of the litter were(20±2)%,(30±2)%,and(40±2)%;and the DWRML values were 1:4,1:6 and 1:8,respectively.The different litters adjusted at different moisture contents were mixed with chicken manure in different DWRML and then placed in different static test chambers,which were real-time monitored the ammonia concentrations.Pure chicken manure without any litter was used as a control group.The four kinds of litter had obvious inhibitory effects on the ammonia emissions from chicken manure under various conditions.There were significant differences among four kinds of litter(p<0.01).Under the same conditions,the best inhibitory effect was achieved by using tea leaves,followed by straw,rice husk,and sawdust.The IMC of litter had no significant effects on the ammonia inhibition(p>0.05).The DWRML had no significant effects on ammonia emission inhibition for tea leaves(p>0.05),but had a significant effects on the ammonia emission inhibition for the other three kinds of litter(p<0.05).The pH value of tea leaves had no significant effects on the inhibition of ammonia emissions(p>0.05).The mixed litter made of tea leaves and sawdust,rice husk,or straw were significantly better than the tea leaves and other single litter(p<0.01).It indicated that adding appropriate amount of tea leaves in the litter can effectively inhibit ammonia emissions from chicken manure.

Estimation for ammonia emissions at county level in China from 2013 to 2018

Ammonia (NH_(3)) can interact with other trace chemicals in the atmosphere,significantly impacting atmospheric chemistry and global climate change.China is a largely agricultural country with high consumption of nitrogen fertilizer and large livestock herds,resulting in high NH_(3) emissions.In this study,a comprehensive county-level inventory of Chinese NH_(3) emissions from 2013 to 2018 was compiled.Based on previous research,an estimate of NH_(3) emissions from household coal combustion was added to the inventory.The estimation of emissions from open biomass burning was improved by using a method based on fire radiative energy (FRE).The total NH_(3) emissions in China increased from 2013 (9.64 Tg) to 2015 (9.75 Tg),and then decreased to 9.12 Tg in 2018.Emissions from fossil fuels reached a peak value in 2018,accounting for 8.4%of total emissions,while fertilizer application and livestock waste were responsible for fewer emissions than in previous years,accounting for 27.7%and 49.9%of the total from non-fossil fuel sources,respectively.The highest emission rates were in central and southwestern China.Seasonally,NH_(3) emissions peaked in spring and summer.The inventory had a 1-km spatial resolution and a monthly temporal resolution,which confirmed its suitability for global and regional air quality simulations.

Nitrogen mobility,ammonia volatilization,and estimated leaching loss from long-term manure incorporation in red soil

Nitrogen（N） loss from fertilization in agricultural fields has an unavoidable negative impact on the environment and a better understanding of the major pathways can assist in developing the best management practices. The aim of this study was to evaluate the fate of N fertilizers applied to acidic red soil（Ferralic Cambisol） after 19 years of mineral（synthetic） and manure fertilizer treatments under a cropping system with wheat-maize rotations. Five field treatments were examined： control（CK）, chemical nitrogen and potash fertilizer（NK）, chemical nitrogen and phosphorus fertilizer（NP）, chemical nitrogen, phosphorus and potash fertilizer（NPK） and the NPK with manure（NPKM, 70% N from manure）. Based on the soil total N storage change in 0–100 cm depth, ammonia（NH_3） volatilization, nitrous oxide（N_2O） emission, N plant uptake, and the potential N leaching loss were estimated using a mass balance approach. In contrast to the NPKM, all mineral fertilizer treatments（NK, NP and NPK） showed increased nitrate（NO_3~–） concentration with increasing soil depth, indicating higher leaching potential. However, total NH_3 volatilization loss was much higher in the NPKM（19.7%） than other mineral fertilizer treatments（≤4.2%）. The N_2O emissions were generally low（0.2–0.9%, the highest from the NPKM）. Total gaseous loss accounted for 1.7, 3.3, 5.1, and 21.9% for NK, NP, NPK, and NPKM treatments, respectively. Estimated N leaching loss from the NPKM was only about 5% of the losses from mineral fertilizer treatments. All data demonstrated that manure incorporation improved soil productivity, increased yield, and reduced potential leaching, but with significantly higher NH_3 volatilization, which could be reduced by improving the application method. This study confirms that manure incorporationis an essential strategy in N fertilization management in upland red soil cropping system.

Effect of partial pit exhaust ventilation system on ammonia removal ratio and mass transfer coefficients from different emission sources in pig houses

A partial pit exhaust ventilation(PPEV)system installed below the slatted floor has been widely used in fattening pig barns nowadays in Denmark.Experimental tests showed that annually around 50%of ammonia emissions was collected by PPEV system.However,the percent of emissions collected by PPEV system from different emission sources including slurry manure surfaces,top surfaces,bottom surfaces and side surfaces of the slatted floor has not been investigated as well as the mass transfer coefficients.This study applied CFD modeling to investigate the removal ratio of ammonia emissions from four emission surfaces including the top,side,bottom surfaces of the slatted floor and slurry manure surfaces.The CFD model was validated by experimental air speeds measured in a room equipped with two full-scale pigpens.The validated CFD model was further adopted to simulate cases under five ventilation rates(2000-4000 m^(3)/h),four emission sources and two locations of PPEV system exhaust.The results showed that the removal ratios of ammonia emissions by PPEV system from the four emission sources were generally higher for the cases that the PPEV exhaust was installed opposite to the air supplier than the values of those cases that the PPEV exhaust was located at the same side of side wall air supplier.The removal ratios of ammonia emissions were the highest with the emission source of slurry manure surface and generally 30%higher than the values of other cases.The mass transfer coefficients with the emission sources on the side surfaces of the slatted floor were the largest.The results indicated that the airflow patterns and locations of emission sources greatly influenced the removal ratios of ammonia emissions and ammonia mass transfer coefficients.

Rice productivity and profitability with slow-release urea containing organic-inorganic matrix materials

Applying slow-release fertilizers is possible means for reducing nitrogen(N) loss in rice production. Matrix-based fertilizers represent novel slow-release fertilizers. To date, there is little consensus about the effect of combined addition of organic and inorganic matrix materials on rice production. We developed a slow-release urea fertilizer with selected organic and inorganic matrix materials. The study aimed to: i) determine the effect of the slow-release urea on rice yield, profit, and agronomic efficiency and ii) elucidate its possible mechanisms. A two-year field experiment was conducted during 2015–2016. Besides,laboratory experiments were conducted to determine the potential N loss risk. Three treatments were set up: control without N application(CK), regular urea treatment(RU, 150 kg N ha^(-1)), and slow-release urea treatment(SU, 150 kg N ha^(-1)). The results showed that rice biomass and grain yield were significantly higher in SU than in RU(P < 0.05). The higher panicle density in SU was largely responsible for the greater grain yield. Net profit in SU was US$450 ha^(-1), higher than in RU. Agronomic efficiency was significantly greater in SU than in RU(P < 0.05). Rice height, root area, leaf chlorophyll, leaf nitrate reductase activity, and leaf glutamine synthetase activity were larger in SU than in RU. Less N loss and greater soil N availability were partly responsible for the improvements in rice growth traits and physiological parameters in SU. Overall, the slow-release urea is a promising fertilizer for rice production.

A green eco-environment for sustainable development:framework and action

Following its 40-year reform and‘Open Door’policy,China has recently proposed a new approach to green development and rural revitalization—the idea of Agriculture Green Development(AGD),with the key feature of creating a green eco-environment.In this minireview we introduce the definition,theory,framework and major components of a green eco-environment as a key part of the AGD.We define a green eco-environment as including four key elements or measures:(1)a green ecoenvironmental indicator system;(2)environmental monitoring and warning networks;(3)emission standards and environmental thresholds for key pollutants;(4)emission controls and pollution remediation technologies.We have used Quzhou County(a typical county in the center of the North China Plain)as an example to show how detailed air,water and soil monitoring networks,as well as improved farmer practices and pollution control measures(especially ammonia emission mitigation and PM2.5 pollution reduction),can begin to create a green eco-environment in China and that AGD is possible.We conclude by stressing the need to improve the framework and practice for a green eco-environment,especially the importance of linking proposals and practices for a green eco-environment with the United Nations high priority Sustainable Development Goals.

IMPROVING NITROGEN SAFETY IN CHINA: NITROGEN FLOWS, POLLUTION AND CONTROL

The impacts of nitrogen on environmental quality,greenhouse gas balances,ecosystem and biodiversity in China are of great concern given the magnitude of demand for food and energy.Comprehensive summaries of historic N flows and their critical threats and sustainable management are urgently needed.This paper initially reviews the historical trends of N flows in China and identifies the critical threats of N loss.Subsequently,it describes some recent success stories of N management,and finally indicates barriers to N pollution control.This review highlights three key points.Firstly,a steady increase of N input in China has led to a series of environmental problems via leaching and runoff,ammonia emissions and denitrification.Secondly,although great efforts to improve N management and N safety in China,further quantifications of N flows and analysis of their underlying mechanisms are needed to improve the understanding of the N cycle and pollution control.Finally,it proposes that the best available technologies combined with regulatory plans,laws,projects and policies should be implemented to overcome current barriers in N control and achieve a balance between the sustainable use of N resources and environmental conservation in China.