Greenhouse Gas Production In Soils Research Articles

Time to Transition: Barriers and Opportunities to Farmer Adoption of Soil GHG Mitigation Practices in Dutch Agriculture

As the second largest exporter of agricultural products worldwide, the Netherlands is a production hub, a leading example of high yields per hectare. However, this productivity includes intensive farming practices, placing a risk on the climate through the emission of greenhouse gases N2O and CO2 from soil. To meet global efforts, the Netherlands must reduce its climatic impact, including soil emissions, but the transition to alternative farming practices can be challenging. This research identifies the barriers and opportunities for arable farmers to adopt practices which mitigate emissions from agricultural soils, and consists of a literature review, informant interviews, and semi-structured interviews with farmers, policy-makers, and boundary organizations. Main findings are (1) a lack of awareness by farmers of their soil greenhouse gas production, and (2) six barriers and five opportunities for farmer adoption with placement of these findings into different steps of adoption. Critical barriers include economic challenges, personal mindset, on-farm complications, and the need to reconcile different stakeholders' rates of adoption. Opportunities lie with farmers becoming interested and able to quantify soil health, positive framing in the media, and policies or economic mechanisms to assist farmers. If the Netherlands can transition its farming system, the opportunities for the global food system could be significant.

Long-term effects of biochar application on greenhouse gas production and microbial community in temperate forest soils under increasing temperature

Biochar management has been proposed as a promising strategy to mitigate climate change. However, the long-term effects of biochar amendment on soil greenhouse gas (GHG) production and microbial community in forest ecosystems under projected warming remain highly uncertain. In this study, we conducted a 49-day incubation experiment to investigate the impact of biochar application on soil physico-chemical properties, GHG production rates, and microbial community at three temperature levels using a temperate forest soil amended with spruce biochar four years ago. Our results showed that temperature exerted a positive effect on soil CO2, CH4 and N2O production, leading to an increase in total global warming potential by 169% and 87% as temperature rose from 5 to 15 °C and from 15 to 25 °C, respectively, and thus a positive feedback to warming. Moreover, warming was found to reduce soil microbial biomass significantly, but at the same time promote the selection of an activated microbial community towards some phyla, e.g. Acidobacteria and Actinobacteria. We observed that biochar amendment reduced soil CH4 consumption and N2O production in the absence of litter by 106% and 94%, respectively, but did not affect soil CO2 production. While biochar had no significant influence of total global warming potential of forest soil, it could promote climate change mitigation by increasing the total soil carbon content by 26% in the presence of litter. In addition, biochar application was shown to enhance soil available phosphorus and dissolved organic carbon concentrations, as well as soil microbial biomass under a warmer environment. Our findings highlighted the potential of spruce biochar as a soil amendment in improving soil fertility and carbon sequestration in temperate forest over the long term, without creating any adverse climatic impacts associated with soil GHG production.

Multiple trade‐offs between maximizing yield and minimizing greenhouse gas production in Chinese rice croplands

AbstractGlobally, paddy fields are a major anthropogenic source of greenhouse gas (GHG) emissions from agriculture. There is, however, limited understanding of relationships between GHG production with fertilizer management, rice varieties, and soil variables. This information is crucial for minimizing the climatic impacts of rice agriculture. Here, we examined the relationships between soil GHG production and management practices throughout China. The current doses of N‐fertilizer (73–272 kg ha−1) were negatively correlated with rice yield and with CO2 or CH4 production and positively correlated with N2O production, thus suggesting N‐overfertilization. Impacts on soil traits such as decreasing pH or the availabilities of other nutrients could be underlying these relationships. Rice yield was highest, and GHG production was lowest at sites using intermediate levels of P‐ and K‐fertilization. CO2 and CH4 production and emissions were positively related with soil water content. The yield was higher, and N2O productions were lower at the sites with japonica rice. Our results strongly suggest that current high doses of N‐fertilizers could be reduced to thus avoid the negative effects of excessive N input on GHG production without any immediate risk of rice production loss. Current intermediate doses of P‐ and K‐fertilization should be adopted across China to further improve rice production without the risk of GHG emissions. The use of different rice varieties and strategies of water management should be reexamined in relation to crop production and GHG mitigation.

Pyrolysis biochar has negligible effects on soil greenhouse gas production, microbial communities, plant germination, and initial seedling growth

Biochar has been promoted as a soil amendment that enhances soil quality and agronomic productivity and reduces greenhouse gas production. However, these benefits are not always realized. A major hurdle to the beneficial use of biochar is our limited knowledge regarding the mechanisms directing its effects on soil systems. This project aimed to eliminate some of this uncertainty by examining the biological responses (plant productivity, greenhouse gas production, soil microbial community structure) of a suite of soils (10) to the addition of biochars produced by different processes (pyrolysis, gasification, burning) from a range of feedstocks (corn stalks, hardwood, grass). Results indicated that these three responses were not significantly impacted by the addition of pyrolysis biochars from different feedstocks at 1 and 5% (w/w) addition levels. On the other hand, both an open-air burned corn stalk (5%) and raw corn stalks (1 and 5%) additions did alter the measured soil functionality. For example, the 5% burnt corn stalks addition reduced total above ground plant biomass (∼30%), increased observed N2O production by an order of magnitude, and altered soil bacterial community structure. The bacterial groups that increased in relative abundance in the burnt corn stalks-amended soils included families associated with cellulose decomposition (Chitinophagaceae), plant pathogens (Xanthomonadaceae), and biochar/charcoal-amended media (Gemmatimonadetes). In contrast, the abundance of these bacterial groups was not impacted by the pyrolysis biochars. Therefore, this research suggests that pyrolysis biochar represents a stabilized form of carbon that is resistant to microbial mineralization and has negligible effects on soil biological responses.

Effects of industrial and agricultural waste amendment on soil greenhouse gas production in a paddy field in Southeastern China

Controlling the production and subsequent emissions of greenhouse gases (GHGs) from paddy fields is crucial to minimize the climatic impacts arising from crop production. The application of chemical or biological amendments is one possible way to limit the production of GHGs in paddy soils. Yet, few existing studies have examined the impacts of applying fertilizers originated from industrial and agricultural wastes on soil GHG production and its governing factors in subtropical paddy fields. In this study, we examined the effects of various agricultural and industrial amendments, including biochar, steel slag, shell slag, gypsum slag, and slag-derived silicate and calcium fertilizers, on the production potential of GHGs in an early paddy field in southeast China. The mean CO2 production rates from soils amended with steel slag as well as silicate and calcium fertilizers were significantly higher than those of the controls by 13.4% and 18.6%, respectively (P < 0.05). Mean soil CH4 production rates from the plots amended with steel slag, biochar, shell slag, and gypsum slag were significantly lower than those of the controls by 42.5%, 36.1%, 60.8%, and 61.8%, respectively (P < 0.05). Meanwhile, we found no significant difference in mean soil N2O production rates between the control and any of the treatments (P > 0.05). Overall, the soil production rate of CO2 was positively correlated with that of CH4 (P < 0.05), but negatively correlated with that of N2O (P < 0.05). When compared to the controls, the ratio of soil CO2:CH4 production increased significantly in the plots receiving biochar, and silicate and calcium fertilizer amendments (P < 0.05), while that of CO2:N2O production increased significantly only in the biochar-amended plots. Soil CH4:N2O production ratio decreased significantly in the plots amended with steel slag and gypsum slag, as compared to the controls (P < 0.05). Our results suggest that the application of biochar, shell slag and gypsum slag would help reduce greenhouse gas production and mitigate climate change impacts of rice cultivation, largely attributable to the reduction in methanogenesis.

Temperature Sensitivity of Soil Greenhouse Gas Production in Three High‐Arctic Plant Community Types at Cape Bounty, Nunavut

Enhanced precipitation and higher temperatures are expected in the Arctic as the result of future climatic warming. To understand future contributions of high‐arctic ecosystems to the climate system, we need to understand the feedbacks between climate and greenhouse gas production, and how they might vary between plant community types distributed along soil moisture gradients. We incubated intact soil cores in the laboratory to explore the temperature sensitivity of soil greenhouse gas (CO2, CH4, N2O) production across the three main plant community types of Cape Bounty, Nunavut: polar desert, mesic tundra and wet sedge. Two sets of cores (0‐10 cm mineral soil) were incubated in the laboratory at 4, 8, and 12°C for one month. We also measured plant community differences in soil thermal regimes for one year. Mean field temperatures were highest in the polar desert during the summer months, while temperatures in the mesic tundra were lowest during this time. In the winter, soil temperatures were lowest in the polar desert and highest in the wet sedge communities. Initial incubation results demonstrate Q10 values for CO2 production ranging from 2.18 in wet sedge to 8.67 in polar desert soils. We observed a Q10 of 4.03 for CH4 output in mesic tundra soils and a Q10 of 16.42 for N2O output in wet sedge soils. Our results suggest that use of single Q10 values to predict future greenhouse gas emissions from high‐arctic ecosystems would likely underestimate the contribution of these ecosystems to the global climate system in a warmer climate.

Advance in a terrestrial biogeochemical model—DNDC model

Global climate change is one of the most important issues of contemporary environmental safety. Quantifying regional or global greenhouse gas (GHG) emissions and searching for appropriate mitigation measures have become a relatively hot issue in international global climate change studies. The high temporal and spatial variability of GHG emissions from soils makes their field measurement at regional or national scales impractical. To develop emission factors for a wide range of management practices such as those given in the Intergovernmental Panel on Climate Change Tier I methodology are often considered as a convenient technique to estimate emissions, but these can result in substantial errors when applied to specific geographical regions. Accordingly, considering the complexity of greenhouse gas production in soils, process-based models are required to quantify and predict the GHG emissions, and also interpret the intricate relationships among the gas emissions, the environmental factors and the ecological drivers. Several detailed biogeochemical process-based models of GHG emissions have been developed and accepted in recent years to provide regional scale estimate of GHG emissions and assess the mitigation measures. Among these the DNDC (Denitrification–Decomposition) model, as a process-based biogeochemical model, is capable of predicting the soil fluxes of all three terrestrial greenhouse gases: nitrous oxide (N 2O), carbon dioxide (CO 2), and methane (CH 4), as well as other important environmental and economic indicators such as crop production, ammonia (NH 3) volatilisation and nitrate NO 3 - leaching. Originally developed as a tool to simulate GHG emissions generated from agro-ecosystem, DNDC has since been expanded to include ecosystems such as rice paddies, grazed pastures, forests, and wetlands, and the model has attracted worldwide attention to simulate carbon and nitrogen biogeochemical cycles occurring in global ecosystems. This paper introduces the scientific basis underlying the modeling of greenhouse gas emissions from terrestrial soils, brings together the worldwide research undertaken on a wide range of ecosystems to test and verify, improve and modify, and apply the DNDC model to estimate GHG emissions from these systems, and furtherly sums up the advantages and disadvantages of the model for providing a reference for the application and development of the model. Most studies showed that there was a good agreement between the simulated and observed values of CO 2, CH 4 and N 2O emissions from arable, forest and grassland fields at different geographical locations over the world. However, some discrepancies still existed between observed and simulated seasonal patterns of CH 4 and N 2O emissions. Moreover, the DNDC model was mainly tested against experimental data on GHG emissions, but there were a few validations on NO 3 - leaching, soil water dynamics, NH 3 volatilisation which could greatly impact the GHG emissions. With the high development of society and economy, China had been facing a huge challenge between food production and environmental protection. Therefore, it was an urgent task to search optimal measures for optimizing land resource use, increasing crop productivity and reducing adverse environmental impacts. Process-based biogeochemical modeling, as with DNDC, can help in identifying optimal strategies to meet the needs. In future, the DNDC model need to not only improve the capability of predicting the GHG emissions, but also the accuracy of simulating the NO 3 - leaching and soil water dynamics for quantifying the non-point source pollution through modifying the parameters of the model or combining with other models, as SWAT model. The DNDC model will play more and more important role in future studies on global change.