Fertilizer value and greenhouse gas emissions from solid fraction pig slurry compost pellets

The aim of this investigation was to determine the physical and acoustical properties of compacts made from composted pig slurry solid fraction (SF) in order to assess the potential to recycle this agricultural waste as a sound absorber. The compacts were obtained by compression. The physical parameters investigated were bulk density, durability, and particle size distribution. The acoustical features of the compacts were studied with an impedance tube device in order to verify the acoustic absorption coefficient. Two composts were prepared: pig SF compost without a bulking agent (SSFC) and pig SF compost with wood chips as a bulking agent (WCC). The study’s results indicated that compost particles dimension played a key role in the physical and acoustical properties of the compacts: the smaller the particles, the higher the physical and acoustical properties of the compacts. The densification process increased the bulk density of the investigated composts up to 690 kg m−3 for SSFC and 660 kg m−3 for WWC, with, respectively, medium (77.9%) and low (66.5%) durability. The addition of woody bulking agent significantly reduced the absorption coefficient: the best results, in terms of potential use as a sound absorber, were observed for compacts made from composted pig slurry solid fraction without the addition of wood chips.

Aim of the study: The use of pig slurry as fertiliser is associated with gaseous nitrogen (N) losses, especially ammonia (NH3) and nitrous oxide (N2O), leading to environmental problems and a reduction of its fertiliser value. This study evaluates, in an irrigated wheat crop, the effect of different additives mixed with pig slurry to decrease NH3 and N2O losses.Area of study: Middle Ebro valley, SpainMaterials and methods: The treatments were: i) non-N-fertilised control, ii) pig slurry (PS), iii) pig slurry with the urease inhibitor monocarbamide dihydrogen sulphate (PS-UI), iv) pig slurry with a microbial activator in development (PS-A), and v) pig slurry with the nitrification inhibitor 3,4-dimethylpyrazole phosphate (PS-NI). Pig slurry was applied at a target rate of 120 kg NH4+-N ha-1. Ammonia volatilisation was measured using semi-opened static chambers after treatments application at presowing 2016 and side-dressing 2017. Nitrous oxide emissions were measured using static closed chambers after treatments application at the 2017 and 2018 side-dressing.Main results: Ammonia volatilisation was estimated to be 7-9% and 19-23% of NH4+-N applied after presowing and side-dressing applications, respectively. Additives were not able to reduce NH3 emissions in any application moment. PS-NI was the only treatment being effective in reducing N2O emissions, 70% respect to those in PS treatment. Crop yield parameters were not affected by the application of the additives because of the no effect of additives controlling NH3 losses and the low contribution of N2O losses to the N balance (<1 kg N2O-N ha-1).Research highlights: The use of 3,4-dimethylpyrazole phosphate would be recommended from an environmental perspective, although without grain yield benefits.

The micrometeorological mass balance method was used to determine ammonia (NH3) volatilisation following the application of pig or cattle slurry to grassland at sites in the UK and The Netherlands. This method involved the measurement of wind speed and the concentration of NH3 in air at 5 or 6 heights above a treated area; the results were compared with those from a simpler method, which required measurements at only one height. In addition, measurements were made of the amounts of NH3 lost from slurry whilst it was being spread on land with a conventional tractor‐drawn vacuum tanker. Some of the factors influencing volatilisation were examined. Losses of NH3N after spreading were equivalent to between 5 and 27% of the total nitrogen (TV) applied in pig slurry and to 23% for a single experiment with cattle slurry. Despite smaller application rates, losses were greater in The Netherlands than in the UK, apparently because of differences in slurry composition. Losses during spreading represented less than 1% of the total over a 3‐day period. Up to 85% of the total loss of NH3‐N occurred within 12 h of application, the highest rate of loss (12.1 kg NH3‐N ha−1 h−1 being recorded immediately after the application of pig slurry in The Netherlands. Results from the single height method were not significantly different from those obtained by the mass balance method.

Mitigating greenhouse gas emissions and ammonia volatilization from cotton fields by integrating cover crops with reduced use of nitrogen fertilizer

Whole-farm systems modelling of greenhouse gas emissions from pastoral suckler beef cow production systems

Ammonia volatilisation from pig slurry and ANS with DMPP applied to Westerwold ryegrass (Lolium multiflorum Lam., cv. Trinova) under Mediterranean conditions

The cultivation industry occupies a large proportion of greenhouse gas emissions in agriculture. Assessing greenhouse gas emissions from the cultivation industry is pivotal for mitigating emissions and promoting sustainable cultivation. Utilizing greenhouse gas emission calculation methods recommended by the Intergovernmental Panel on Climate Change (IPCC) and other methods, this work evaluated annual emissions and the emission structure of major crops from 2005 to 2021 in the Chengdu Plain, a significant agricultural region in Southwest China. We identified nitrogen fertilizer as the primary contributing factor to high emissions from cultivation production. Subsequently, we analyzed the trend and utilization of nitrogen fertilizer, which proposes essential strategies for reducing greenhouse gas emissions. The results showed that greenhouse gas (GHG) emissions from the cultivation industry in the Chengdu Plain exhibited a growth, fluctuation, and eventual decline trend from 2005 to 2021. The emissions increased from 5,148,900 t in 2005 to 6,289,700 t in 2009, representing a 22.16% increase, and subsequently decreased to 5,109,900 t in 2021, marking a 23.31% decrease. Nitrogen fertilizer application emerges as the primary source of GHG emissions, constituting approximately half of the total, with nitrogen fertilizer manufacturing contributing significantly as well, collectively amounting to about 70%. We also found that the proportion of greenhouse gas emissions attributed to cash crop cultivation has gradually increased over the last decade. Among these crops, vegetables exhibit the highest emissions, comprising nearly half of the total emissions from 2019 onwards. However, the nitrogen fertilizer use efficiency of cash crops is less than 30%, with higher nitrogen surplus, ammonia volatilization, and nitrogen leaching per unit area, and the total amount is higher than that of grain crops. Among cash crops, vegetables exhibit the highest amount of nitrogen surplus, ammonia volatilization, and nitrogen leaching, constituting nearly half of the total amount in the study area since 2019. Our findings significantly affect sustainable and low-carbon cultivation industry development in the study area.

Cattle slurry solid fraction (SF) was composted with increasing rates (0, 25, 33 and 50% v/v) of either Italian ryegrass (Lolium multiflorum L.) straw or gorse (Ulex europaes) to determine the effects of these bulking agents on the physicochemical properties during the composting process and to identify approaches to improve final compost quality. Composting temperatures increased to a maximum of 65°C after 42 days for unamended SF. In contrast, temperatures increased more rapidly in piles mixed with straw (68°C at day 7) or with gorse (74°C at day 3). Gorse or straw addition to SF, therefore, also increased the initial rates of organic matter mineralization. However, potential organic matter (OM) mineralization and compost N concentration decreased with the addition of the bulking agents. C/N ratios declined from 32-38 to a value of 13-17 towards the end of composting and followed a similar trend for all compost treatments. Low compost temperature, low C/N ratio and the small content of NH4+ combined with increased concentrations of NO3− indicated SF composts were stabilized and suitable for use in agriculture. High concentrations of OM (780-840 g kg−1 dry matter (DM)) and total N (28-35 g kg−1 DM), and low electrical conductivity (0.7-1.2 dS m−1) suggested that SF composts would be effective soil amendments with agronomic and environmental advantages. The addition of straw or gorse also enhanced compost sanitation.

Reducing greenhouse gas (GHG) emissions and ammonia (NH3) volatilization by improving fertilization methods to increase crop yield is beneficial for the green and sustainable development of agriculture. This study evaluated the effects of farmer practice fertilization (FP), nutrient expert optimized fertilization (NE—optimized fertilizer usage and time), the application of stable compound fertilizer (SF), and the application of controlled-release coated urea (CRU) on greenhouse gases, NH3 volatilization, and corn yield through field experiments set up in the corn planting area in western Liaoning Province. The results showed that compared with FP treatment, NE could significantly reduce NH3 volatilization by 28% and increase N2O release by 41%. Compared with FP treatment, SF could significantly reduce NH3 volatilization by 48.54%, N2O release by 38.54%, CO2 release by 13.96%, global warming potential (GWP) by 16.60%, and greenhouse gas emission intensity (GHGI) by 27.23%, and could significantly increase corn yield by 15.86%. Compared with FP treatment, CRU could significantly reduce NH3 volatilization by 63.46%, CO2 release by 11.98%, GWP by 10.73%, and GHGI by 13.77%, while increasing N2O release by 6.71%. Overall, NE, SF, and CRU treatments all showed better effects than FP treatment in increasing corn yield or reducing NH3 volatilization and GHG emissions. Among them, SF treatment demonstrated superior performance over NE and CRU treatments in terms of NH3 volatilization, corn yield, and GHGI. Therefore, the application of stable compound fertilizer is the optimal choice for corn planting in western Liaoning, with broad application prospects.

Ammonia volatilization, greenhouse gas emissions and microbiological mechanisms following the application of nitrogen fertilizers in a saline-alkali paddy ecosystem

Abstract. Impacts of simultaneous inputs of crop straw and nitrogen (N) fertilizer on greenhouse gas (GHG) emissions and N losses from rice production are not well understood. A 2-year field experiment was established in a rice–wheat cropping system in the Taihu Lake region (TLR) of China to evaluate the GHG intensity (GHGI) as well as reactive N intensity (NrI) of rice production with inputs of wheat straw and N fertilizer. The field experiment included five treatments of different N fertilization rates for rice production: 0 (RN0), 120 (RN120), 180 (RN180), 240 (RN240), and 300 kg N ha−1 (RN300, traditional N application rate in the TLR). Wheat straws were fully incorporated into soil before rice transplantation. The meta-analytic technique was employed to evaluate various Nr losses. Results showed that the response of rice yield to N rate successfully fitted a quadratic model, while N fertilization promoted Nr discharges exponentially (nitrous oxide emission, N leaching, and runoff) or linearly (ammonia volatilization). The GHGI of rice production ranged from 1.20 (RN240) to 1.61 kg CO2 equivalent (CO2 eq) kg−1 (RN0), while NrI varied from 2.14 (RN0) to 10.92 g N kg−1 (RN300). Methane (CH4) emission dominated the GHGI with a proportion of 70.2–88.6 % due to direct straw incorporation, while ammonia (NH3) volatilization dominated the NrI with proportion of 53.5–57.4 %. Damage costs to environment incurred by GHG and Nr releases from current rice production (RN300) accounted for 8.8 and 4.9 % of farmers' incomes, respectively. Cutting N application rate from 300 (traditional N rate) to 240 kg N ha−1 could improve rice yield and nitrogen use efficiency by 2.14 and 10.30 %, respectively, while simultaneously reducing GHGI by 13 %, NrI by 23 %, and total environmental costs by 16 %. Moreover, the reduction of 60 kg N ha−1 improved farmers' income by CNY 639 ha−1, which would provide them with an incentive to change the current N application rate. Our study suggests that GHG and Nr releases, especially for CH4 emission and NH3 volatilization, from rice production in the TLR could be further reduced, considering the current incorporation pattern of wheat straw and N fertilizer.

Ammonia (NH3) volatilization and greenhouse gas (GHG) emission from rice (Oryza sativa L.) fields contaminate the atmospheric environment and lead to global warming. Field trials (2013-2015) were conducted to estimate the influences of different types of fertilization practices on grain yield, NH3 volatilization, and methane (CH4) and nitrous oxide (N2O) emissions in a double rice cropping system in Central China. Results showed that grain yields of rice were improved significantly by using slow/controlled-release urea (S/C-RU). Compared with farmers' fertilizer practice (FFP) treatment, average annual grain yield with application of polymer-coated urea (CRU), nitrapyrin-treated urea (CP), and urea with effective microorganism (EM) treatments was increased by 18.0%, 16.2%, and 15.4%, respectively. However, the effects on NH3 volatilization and CH4 and N2O emissions differed in diverse S/C-RU. Compared with that of the FFP treatment, the annual NH3 volatilization, CH4 emission, and N2O emissions of the CRU treatment were decreased by 64.8%, 19.7%, and 35.2%, respectively; the annual CH4 and N2O emissions of the CP treatment were reduced by 33.7% and 40.3%, respectively, while the NH3 volatilization was increased by 18.5%; the annual NH3 and N2O emissions of the EM treatment were reduced by 6.3% and 28.7%, while the CH4 emission was improved by 4.3%. Overall, CP showed the best emission reduction with a decrement of 34.3% in global warming potential (GWP) and 44.4% in the greenhouse gas intensity (GHGI), followed by CRU treatment with a decrement of 21.1% in GWP and 31.7% in GHGI, compared with that of the FFP treatment. Hence, it is suggested that polymer-coated urea can be a feasible way of mitigating NH3 volatilization and CH4 and N2O emission from rice fields while maintaining or increasing the grain yield in Chinese, the double rice cropping system.

Impacts of vermicompost application on crop yield, ammonia volatilization and greenhouse gases emission on upland in Southwest China

A volatilização de amônia é umas das principais formas de perdas de nitrogênio, especialmente com a aplicação de dejetos, devido a sua distribuição a lanço, em superfície. Este trabalho teve por objetivo determinar as perdas de N por volatilização de amônia em função de doses e horários de aplicação de dejeto líquido de suínos. O trabalho foi conduzido a campo em fevereiro, maio, outubro e dezembro de 2001, sendo que, em fevereiro e dezembro, aplicou-se o dejeto em dois horários (10 e 18h). As doses testadas foram 0, 20, 40 e 80m³ ha-1 e as determinações das perdas de amônia foram feitas às 3, 6, 12, 24, 30, 36, 42, 48, 60, 72, 96, 120, e 144 horas após a aplicação do dejeto, totalizando um período de avaliação de seis dias. O uso de menores doses de dejeto líquido de suínos minimizou as perdas de N por volatilização de amônia. Os picos de perda ocorreram nas primeiras horas após a aplicação indicando que, quando possível, a sua incorporação seria uma alternativa à diminuição nas perdas de N por volatilização de amônia. O horário de aplicação do dejeto não afetou de maneira consistente as perdas de N por volatilização de amônia.

Greenhouse gas (GHG) emissions from agricultural soils can accelerate climate change, therefore, different soil fertilization techniques should be assessed before application to reduce GHG emissions. Pig slurry applications can greatly influence soil carbon dioxide (CO2), nitrous oxide (N2O), and ammonia (NH3) emissions of arable fields; thus, it is important to find site-specific techniques to lessen any negative environmental impacts. In this study, we examined the short-term effect of pig slurry application techniques of spreading and injection on soil greenhouse gas and NH3 emissions under different irrigation amounts. We used the dynamic chamber method with in-situ gas analyzers. Our study showed that there were elevated emissions during the first week after slurry application; however, the difference between GHG emissions of spreading and injection treatments were not significant. Elevated GHG emissions (213–338% and 250–594% in the case of CO2 and N2O emissions, respectively) were observed under dry circumstances compared to irrigated treatments, as well as significantly higher NH3 emissions occurred for surface spreading under non-irrigated (dry) circumstances compared to other treatments. There were no statistically significant differences between the soil chemistry of different application techniques. However, pig slurry increased the available nitrogen forms (ammonium- and nitrate-nitrogen), which caused N2O and NH3 peaks regardless of treatment type. Leachate chemistry was more affected by irrigation strategies than application techniques. Our study highlights the importance of soil conditions at the time of application, rather than the application technique for fertilization using pig slurry.