Soils with Smart Carbon

Prof. Genxing Pan1

1Nanjing Agricultural University, Nanjing, China

Enhancement of carbon storage in global soils has been urged as per the “C 4 per mil Initiative”, launched following “the Paris Agreement” for climate change mitigation. However, what kind of carbon should be increased or how the increased carbon could serve soil fertility and ecosystem functioning while mitigate climate change, has been not yet well understood. Global agricultural soils have been depleted organic carbon and therefore have a big potential to feed carbon. Any forms of organic carbon ultimately derived from biomass could help to build up soil C storage but their effects on carbon cycling and food production are widely variable. While to captured or stabilize C in soil, we need carbon to restore soil fertility and soil health and to promote plant growth and food quality, the “Smart C” in agriculture. Such carbon should have stable structure, high reactivity and bioactivity (for example, plant growth/metabolism promotion). Biochar, as an example, is engineered carbon from crop straw and functions in improving soil aggregation/structure, root growth and plant development, and in stabilizing potentially toxic metals, organic pollutants and even pathogenic microbes. The co-benefits to food production, soil/water conservation and environment protection should be assessed and accounted for in the fight against climate change. The characterization, processing and production, and application of smart carbon in agriculture deserve urgent international collaboration, particularly under the framework of “C 4 per mil” action.


Biography:

Dr Genxing Pan is  a science leader of soil science in Nanjing Agricultural University. He has been devoted his main career to science and technology of soil carbon enhancement in agricultural, particularly of agrochar, in boosting soil C stock and crop productivity for climate change and food

Soil organic carbon stocks as an indicator of land degradation for Sustainable Development Goal 15

Dr Jacqueline England1, Professor Raphael Viscarra Rossel2, Dr Stephen Roxburgh3, Neil McKenzie3, Dr Carly Green4, Dr Glenn Newnham1, Dr Neil Sims1, Dr Alex Held3,5

1CSIRO Land and Water, Clayton South, Australia, 2Curtin University, Perth, Australia, 3CSIRO Land and Water, Canberra, Australia, 4Global Forest Observation Initiative, Rome, Italy, 5CSIRO Astronomy and Space Science, Canberra, Australia

Since 2010 there have been several global and regional targets and initiatives to halt and reverse land degradation and restore degraded land; the most recent being the 2030 Agenda for Sustainable Development and the Sustainable Development Goals (SDGs). SDG indicator 15.3.1, the proportion of land that is degraded over total land area, is assessed in terms of change in three sub-indicators: land cover, land productivity and carbon stocks. Each of these sub-indicators represents a unique perspective on the manifestation and assessment of land degradation. Soil organic carbon (C) is the current metric for assessing the carbon stocks sub-indicator. Good practice guidance (GPG) has recently been developed to assist countries to report on SDG indicator 15.3.1, and support countries to achieve their targets for reducing degradation. Without being prescriptive about the sources of data, the GPG aims to ensure technical soundness and consistency in estimation methods as well as comparability of results across countries and over time. The approach used to quantify change in soil organic C stocks will vary depending on the availability of country-specific data and capability. Key challenges include the establishment of appropriate baselines and methods for determination of significant change in soil organic C stocks. The latter is further complicated by the typically slow rate of change in soil organic C in relation to indicator reporting periods. This paper presents some of the key methodological details of the GPG for assessing soil organic C stocks and describes considerations that may assist in national scale monitoring of soil organic C in order to implement national reporting against SDG indicator 15.3.1.


Biography:

Dr Jacqui England is an ecologist with a particular interest in understanding forests and agro-ecosystems to inform their management and restoration. Her research on ecosystem processes in relation to environmental and management factors in these systems has largely focussed on developing tools for accurate carbon accounting, and assessing the co-benefits they provide, to inform policy and influence land management. This work has directly contributed to improving the national carbon accounting tool and to the development of land-based greenhouse gas mitigation methodologies both nationally and internationally.

Challenges and opportunities for making compound fertilizers with biochar and nutrient rich wastes

Dr Daniel Rasse1, Dr Alice Budai1, Mr Simon Weldon1

1NIBIO, Ås, Norway

There is a need for win-win solutions for increasing soil carbon sequestration and improving the recycling of nutrients from organic wastes, thereby benefiting both climate mitigation and food production. In terms of carbon sequestration, biochar has been presented as a major solution for stabilizing vast amounts of carbon in soils. Analysis reveals that biochar technology outcompetes other methods for storing CO2 from bioenergy systems only if it also leads to increases in crop productivity. However, improved agronomic results have not always been forthcoming, especially in temperate fertile soils, and farmers need to see greater agronomic benefits in order to adopt the technology. This is why recent research recommends improving the fertilizer value of biochar by combining it with organic nutrient sources, especially N & P, fixed to or absorbed on its surface. In theory, the solution is ideal; biochar as a sorbent material has the capacity to capture nutrients in waste streams such as digestate and manure, reduce volatile N losses and GHG emissions, improve nutrient use efficiency and reduce N leaching. However, the mechanisms controlling this nutrient retention capacity are still poorly understood. Here, we report on a meta-analysis of biochar properties that control the retention and release of multiple forms of N and P sources. We further discuss implications for making compound fertilizers with biochar and nutrient-rich wastes.


Biography:
Daniel Rasse holds a PhD in soil science from Michigan State University and is currently heading the Soil Quality department at the Norwegian Institute of Bioeconomy Research. He has coordinated the European Networking Programme MOLTER (2008-2013) on molecular structures in the terrestrial C cycle, and is PI of several large-scale projects. His main research focus is on soil organic matter and the factors influencing its accumulation and its feedback on ecosystem functions. In the last decade, he has been working intensively on biochar technology as a mean to increase C sequestration in soil and improve fertility.

New insights into how organic N is depolymerised

A/Prof. Charles Warren1

1University Of Sydney, University Of Sydney, Australia

Despite nitrogen (N) commonly limiting productivity, most soils contain a large pool of N in high molecular weight organic forms.  High molecular weight forms of organic N are in general not directly available for uptake by microbes or plants, and only become available after they have been depolymerised by extracellular enzymes.

Surprisingly little is known about how high molecular weight organic N is depolymerized. A particular challenge is in determining the products that are produced when high molecular weight organic N is depolymerized. Depolymerisation of organic N is often equated with production of the terminal monomers, primarily amino acids.  For example, many assays of enzyme activity focus solely on reactions that produce amino acids.  Studies to date have not determined the chemical profile of products produced by depolymerisation of organic N, and thus we do not know if amino acids are the main products of depolymerisation.

Determining how high molecular weight organic N is depolymerized has proved challenging for two reasons. First, because the products of depolymerisation are rapidly taken up by microbes; and second, because it has proven difficult to identify and quantify complex mixtures of hydrophilic organic N compounds.

This presentation will describe development of mass spectrometry methods to characterize the products of organic N depolymerisation.  We show that while amino acids are produced by depolymerisation they are not the dominant products.  The main depolymerisation products of native organic matter and added proteins are instead peptides. The same peptides that are produced in large quantities by depolymerisation are at vanishingly low concentrations in intact soil, which is consistent with the idea that peptides are preferred N sources for soil microbes.


Biography:

Charlie Warren is an Assoc Prof in the School of Life & Environmental Sciences at The University of Sydney. Charlie’s research career began as an honours student examining photosynthesis at low temperatures. After a decade examining the ecophysiology of photosynthesis, his research began heading belowground: first to examine uptake of organic N, then to examine root exudates and plant-soil interactions. Nowadays much of Charlie’s research focusses on nutrient cycling, in particular the development of novel analytical methods to solve intractable problems.

Bacterial 3-hydroxy fatty acids: Applicability as environmental markers in soils from the French Alps

Mr Pierre Véquaud1, Dr Sylvie Derenne1, Dr Sylvie Collin1, Mrs Christelle Anquetil1, Pr  Jérôme Poulenard2, Dr Pierre Sabatier2, Dr Arnaud Huguet1

1METIS, CNRS/Sorbonne Université/EPHE, Paris, France, 2EDYTEM, Université savoie Mont-Blanc/CNRS, Le Bourget-du-Lac, France

The composition of microbial membrane lipids has been shown to vary with environmental parameters in order to maintain an appropriate fluidity and permeability of the membrane. This is particularly the case for glycerol dialkyl tetraethers (GDGT), used for temperature and pH reconstructions in terrestrial settings, although other environmental parameters might also influence the GDGT distribution. Another family of lipids, 3-hydroxy fatty acids (3-OH FAs) was recently proposed as an alternative to GDGTs. To investigate the applicability of 3-OH FAs as temperature and pH proxies and understand the influence of environmental parameters on these lipids, 49 soils were collected between 200 and 3,000 m altitude in the French Alps. These soils cover a wide range of temperature (0°C to 15°C) and pH (3 to 8) and are representative of the diversity of soil vegetation and pedological covers along the mountain gradients. In agreement with previous studies, a significant correlation is observed between 3-OH FAs and pH. In contrast, no correlation could be shown with mean annual air temperature. Similarly, GDGTs are only poorly correlated with temperature in this sample set. This suggests that other parameters, such as vegetation, soil type or humidity are the main drivers of the variability of 3-OH FA and GDGT distribution. The influence of vegetation type and soil classification was tested on 3-OH FA relative abundances as the sampling allows differentiating 10 types of vegetation and 10 types of soil. Both parameters were shown to have a significant impact on the 3-OH FA distribution. This led us to build a model based on Artificial Neural Network, which allowed the reconstruction of soil types and vegetation with an accuracy of 89 %. This promising approach, developed on soils from the French Alps, will be further applied to a larger number of soil samples and also tested on GDGTs.


Biography:

Distinguished senior scientist (DRCE) CNRS since 2016, Head of the biogeochemistry group of METIS laboratory. My research area is organic geochemistry and I combine various techniques of analytical chemistry to decipher the chemical structure of “geomaterials” to understand their formation pathway and behaviour in the environment. These “geomaterials” belong to a large diversity of natural environments such as sedimentary rocks, soil, natural waters and extraterrestrial materials. I co-authored 218 peer-reviewed papers and supervised 30 PhD students.

Awards: 2009 CNRS Silver Medal, 2019 Geochemical Society Alfred Treibs Medal

Quality of soil organic matter in high-latitude environments: From bulk to water-extractable soil organic matter

Dr Yannick Agnan1, Dr Marie A.  Alexis1, Ms Alice  Kohli2, Dr Edith Parlanti3, Dr Sylvie Derenne1, Ms Mahaut Sourzac3, Ms Christelle Anquetil1, Pr Daniel Obrist4, Dr Maryse Castrec-Rouelle1

1Sorbonne Université, Paris, France, 2Agrocampus Ouest, Angers, France, 3Université de Bordeaux, Talence, France, 4University of Massachusetts, Lowell, Lowell, USA

Soil organic matter in Arctic and Subarctic regions plays a key role for the global carbon cycling. The objective of this study was to evaluate the structure and fate of soil organic matter in the high latitudes by jointly quantifying and characterizing both bulk and water-extractable organic matter in surface soil samples. We compared two study sites with similar tussock tundra ecosystems and distinct mean annual air temperature and permafrost conditions: Abisko, Sweden (−1 °C, discontinuous permafrost) and Toolik, Alaska, USA (<−8 °C, continuous permafrost). Both sites presented different bulk soil organic matter compositions: higher C/N and alkyl C/O-alkyl C ratios were reported at Abisko (27.1 ± 8.6 and 0.57 ± 0.17, respectively) compared to Toolik (17.4 ± 2.3 and 0.44 ± 0.11, respectively). These patterns are attributed to either distinct decomposition stages linked to climate conditions or distinct organic matter inputs with local vegetation influences. Extractable fractions indicated higher water-extractable organic matter concentrations in the colder site (i.e., at Toolik with 4.38 mg gsoil−1 of water-extractable organic carbon and 0.25 mg gsoil−1 of water-extractable total nitrogen) that we attribute to a higher pool of potentially mobilizable matter from a more preserved soil organic matter. Overall, the most significant result is that the intra-site heterogeneity of the soil organic matter quality was higher than the inter-site heterogeneity, in the bulk as well as in the water-extractable fractions. Finally, the qualities of both bulk and extractable fractions were not directly linked together: some specific patterns observed in the bulk fraction (e.g., locally lower alkyl C/O-alkyl C ratios) were not observed in the extractable one, and reciprocally (e.g., singular fluorescence signature).


Biography:

Since 2008, M. A Alexis is assistant professor in Biogeochemistry at the Sorbonne Université (Paris – France). Her studies focus on the characterization of soil organic matter (at elementary, isotopic, or molecular scales) to understand its dynamics and its response to global changes. She especially studied the quality and features of thermally altered organic matter, in soils naturally affected by biomass fires, and in hearths after prehistorical human use. She presently also works on the production of dissolved organic matter through soil leaching and on the consequences for carbon storage and for transfer and dynamics of trace elements in high latitude environments.

Minimal soil disturbance and increased residue retention increase soil carbon in rice-based cropping systems on the Eastern Gangetic plain

Dr Md Khairul Alam1, Professor Richard W Bell2, Dr M E Haque2, Professor Abdul Kader2

1Bangladesh Agricultural Research Institute, Gazipur, Bangladesh, 2Murdoch University, Perth, Australia

Little is known about the impact of conservation agriculture (CA) practices on soil carbon dynamics in the intensive triple-cropping, rice-based systems of the Eastern Gangetic Plain (EGP). Our aim was to determine whether CA in these systems involving non-puddled transplanting (NP) of wetland rice and strip planting of dryland crops plus increased residue retention would increase the C storage in soils relative to conventional crop establishment practices. Long-term field experiments were studied in two locations of northwestern Bangladesh to determine C turnover as well as examining C cycling under three soil disturbance levels (conventional tillage-CT, strip planting-SP and bed planting-BP) in combination with low residue (straw) retention(LR) and increased residue retention (HR) in Calcareous Brown Floodplain (Alipur) and Grey Terrace soil (Digram). The total nitrogen(N), organic C(SOC), microbial biomass C (MBC) and water-soluble C(WSC) values were measured in soil samples collected at different stages during the growth of the 13th and 14th crops at Alipur and the 12th and 13th crops at Digram since treatments commenced. At each location, SP and BP with LR or HR retained more SOC from C inputs than CTHR and CTLR. In general, the CO2 emissions under SPLR and SPHR were 13 to 59 % lower than those under CT and BP with LR and HR. The higher levels of C mineralization were associated with higher WSC contents in the soil. Similarly, in SPLR and SPHR, the potentially mineralizable C was higher, while decay rate constant was lower. The HR with SP and NP after 14 crops at Alipur and 13 crops at Digram modified the C cycle by decreasing C emissions and increasing the levels of total organic C in the soil. The application of both minimal soil disturbance and HR enhanced SOC concentrations in the soils under rice-based cropping systems on the EGP.


Biography:

Dr Alam has 13 years of experience on land management and crop production. He has expertise on soil C sequestration, crop establishment practices, nutrient management, global warming potential mitigation. Dr Alam has also published manuscripts on the research activities in different reputed journals. Dr Alam has recently finished his PhD on “Assessment of soil carbon sequestration and climate change mitigation potential of conservation agriculture practices on the Eastern gangetic Plains”.

Soil microbiome and carbon under the A (horizon)

Dr Charles Rice1, Dr. Marcos  Sarto1, mr. Carlos Pires1, Mr. James Lin1

1Kansas State University, Manhattan, United States

Central USA was dominated by tallgrass prairie across a large precipitation gradient broadly representative of both current and future precipitation regimes. Much of the prairie is now under cultivation. Much research has focused on the role of the soil microbiome in the global C cycle, given soils can serve as a sink or source of greenhouse gases. These microbial functions are strongly influenced by microbial resource limitations and available moisture. Microbes also influence soil structure. Soil aggregation mediates soil chemical, physical, and biological properties and improves soil quality and sustainability. Identifying drivers of the long-term persistence of soil organic C represents another challenge for projecting future interactions between soil properties, water, and soil microbial behavior.  The aim of this study was to investigate the soil biophysical properties across a precipitation gradient with different land uses.  Soil profiles were sampled to 1m for soil C and N, aggregate structure, and microbial community composition by phospholipid fatty acid (PLFA) analysis. Microbial biomass C (MBC) in the native prairie and agriculture were not significantly affected by the precipitation gradient.  Large aggregates (>2 mm) were higher in the native prairie at central> west and east. Large aggregates (>2 mm) were higher in the native prairie relative to agriculture.

Total PLFA was higher in the native prairie with greater precipitation. Total PLFA was higher in the native prairie relative to agriculture.  Higher AMF content was found under greater precipitation regime in all land uses. The aggregate structure was highly correlated to fungal and mycorrhizal fungi biomass. Relations with C, depth, and microbial community composition are being explored.


Biography:

Charles (Chuck) Rice is a University Distinguished Professor and holds the Vanier University Professorship at Kansas State University.  He is a Professor of Soil Microbiology in the Department of Agronomy.

Abiotic and microbial degradation of biochars depend on biochars’ chemistry and temperature under laboratory conditions

Dr Muhammad Riaz1, Mr. Aqeel Ahmad1, Dr. Muhammad Saleem Arif1, Mrs. Samar Fatima1, Dr. Tahirs Yaseem1, Dr.  Muhammad Bilal Shakoor1, Dr. Muhammad  Rizwan1, Ms.  Maryam Adil1, Dr.  Shafaqat  Ali1

1Department of Environmental Sciences & Engineering, Government College University Faisalabad, Pakistan, Faisalabad, Pakistan

Biochar is a carbon (C) rich material produced from pyrolysis of biomass under no or limited supply of oxygen. Use of biochar for multiple purposes depends on its physico-chemical characteristics-driven stability and decomposition. We investigated abiotic and microbial mineralization of a range of low-pyrolysis temperature (400 °C) biochars at 15, 30 and 45 °C incubation temperatures. Biochars were developed from eucalyptus leaves (ELB), wheat straw (WSB), poultry manure (PMB), cotton sticks (CSB), vegetable waste (VWB), lawn grass (LGB) and citrus leaves (CLB). In addition to elemental composition, biochars were characterized for pH, electrical conductivity (EC), labile organic C (L-OC) and LOC characteristics including specific ultraviolet absorbance (SUVA), aromaticity, hydrophilic and hydrophobic C fractions and total phenolic contents. Carbon mineralization was measured for seven days using abiotic (sterile incubation with mineral nutrients) and microbial (microbial inoculum with mineral nutrients) experimental conditions. We found that abiotic degradation of biochars were generally less than microbial degradation, however, these patterns significantly varied between feedstocks and incubation temperatures.  Both abiotic and microbial C mineralization was also strongly controlled by incubation temperatures. However, increase in incubation temperature was not always associated with acceleration in abiotic and microbial CO₂ efflux. Percent C mineralized (PCM) of L-OC was higher under microbial incubation at 30 °C and higher for PMB, CSB and CLB.  Water extractable OC (WEOC) also showed significant variations with respect to biochars and incubation temperature whereas WEOC correlated significantly positively with CO₂ efflux under abiotic and microbial incubation conditions. Characteristics of L-OC seem to have strong influence on both abiotic and microbial biochar degradation; positive relationships with pH, volatile matter, L-OC and total phenolics and negative relationships with EC and SUVA.  These observations warrant the consideration of abiotic (chemical & photo-oxidation, solubilization) and microbial decomposition of biochars before its application to soils.


Biography:

Dr. Muhammad Riaz is working as an Associate Professor in the Department of Environmental Sciences & Engineering, Government College University Faisalabad (GCUF), Pakistan. He earned his PhD in Environmental Sciences from the University of York, UK. His research is mainly focused on soil biogeochemistry, CNP cycling in agroecosystems, biochar as a tool for soil C sequestration and soil quality management, and dynamics of soil organic matter cycling and recycling in semi-arid and arid agroecosystems.

Dynamics of residue 13C and 15N at various depths in diverse soils

Dr Monika Gorzelak1, Dr Ed Gregorich2, Dr Bobbi Helgason4, Dr Mike Beare3, Dr Denis Curtin3, Dr Ben Ellert1, Dr Henry Janzen1

1Agriculture And Agri-food Canada, Lethbridge, Canada, 2Agriculture and Agri-Food Canada, Ottawa, Canada, 3The New Zealand Institute of Plant and Food Research, Christchurch, New Zealand, 4University of Saskatchewan, Saskatoon, Canada

Plant litter decay and the persistence of its carbon (C) and nitrogen(N) crucially affect soil health and can impact soil carbon sequestration. We conducted a long-term experiment that asks: does the depth in soil profiles influence the processes and extent of residue turnover? Barley residue, highly enriched with 13C and 15N, was placed in mesh bags and buried at three depths in the soil profile (5-10 cm, 20-25 cm, 40-45 cm) at three sites with different climate and soil properties (Lincoln, New Zealand; Ottawa and Lethbridge Canada). The mesh bags were periodically retrieved over about a decade, and analyzed for 13C and 15N to determine recovery and also distribution in microbial phospholipid fatty acids (PLFA). At all sites and treatments, decay followed typical 1st-order kinetics, with high initial rates gradually diminishing over time. Decomposition was slower in the cold site (Lethbridge) than at other sites (Ottawa, Lincoln). Depth in soil profiles had no consistent effect on recovery of 13C, even though the residue was processed by different microbial communities, as determined by PLFA analysis. Dynamics of 15N showed patterns similar to those of 13C, although recovery was usually higher, indicating recycling of the N. The absence of a strong depth effect on litter turnover raises intriguing questions about opportunities for sequestering C in soil profiles, and invites further study of how microbes at depth process C and N inputs.


Biography:

Monika Gorzelak is a new Soil Health Research Scientist with Agriculture and Agri-Food Canada specializing in soil microbial ecology. She has a PhD from UBC in Vancouver Canada with a thesis on communication between trees through mycorrhizal networks.

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SOIL ORGANIC MATTER

7th International Symposium
Soil Organic Matter

6 – 11 October 2019

Hilton Adelaide

Adelaide, South Australia

Australia

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