21st Century soil science must deeply grapple with the enormity of the agricultural impact on soils, and the complex ways in which this impacts soil sustainability. The first step is to remove the ...cloud of mysticism that sometimes surrounds soil and farming, reframe the narrative, and be clear about the enormous difficulty of creating a truly steady state and/or C-neutral soil management system. The objective of this paper is to examine the global footprint of agriculture on soils, and its impact on soil erosion, carbon, and nutrients. Stabilizing any one of these 3 mass balances globally will require complex and highly integrated collaborations between social scientists, policy experts, engineers, farmers, politicians, and natural scientists. There are no magical or simple solutions. Yet, there are untapped opportunities for research and solution-driven activities that can help to create a new framework for more effective efforts by our science to address wicked societal problems.
In this book Ron Amundson examines two hundred years of scientific views on the evolution-development relationship from the perspective of evolutionary developmental biology (evo-devo). This ...perspective challenges several popular views about the history of evolutionary thought by claiming that many earlier authors had made history come out right for the Evolutionary Synthesis. The book starts with a revised history of nineteenth-century evolutionary thought. It then investigates how development became irrelevant with the Evolutionary Synthesis. It concludes with an examination of the contrasts that persist between mainstream evolutionary theory and evo-devo. This book will appeal to students and professionals in the philosophy and history of science, and biology.
Soil and human security in the 21st century Amundson, Ronald; Berhe, Asmeret Asefaw; Hopmans, Jan W. ...
Science (American Association for the Advancement of Science),
05/2015, Letnik:
348, Številka:
6235
Journal Article
Recenzirano
Odprti dostop
Global soil resources under stressThe future of humanity is intertwined with the future of Earth's soil resources. Soil provides for agriculture, improves water quality, and buffers greenhouse gases ...in the atmosphere. Yet human activities, including agricultural soil erosion, are rapidly degrading soil faster than it is naturally replenished. At this rate, human security over the next century will be severely threatened by unsustainable soil management practices. Amundson et al. review recent advances in understanding global soil resources, including how carbon stored in soil responds to anthropogenic warming. Translating this knowledge into practice is the biggest challenge remaining.Science, this issue 10.1126/science.1261071 Human security has and will continue to rely on Earth's diverse soil resources. Yet we have now exploited the planet's most productive soils. Soil erosion greatly exceeds rates of production in many agricultural regions. Nitrogen produced by fossil fuel and geological reservoirs of other fertilizers are headed toward possible scarcity, increased cost, and/or geopolitical conflict. Climate change is accelerating the microbial release of greenhouse gases from soil organic matter and will likely play a large role in our near-term climate future. In this Review, we highlight challenges facing Earth's soil resources in the coming century. The direct and indirect response of soils to past and future human activities will play a major role in human prosperity and survival.
•On the California coast N is tightly cycled by biological activity whereas S appears to be in excess.•Depth profiles of C, N, and their isotopes provides insights into rates of C and N cycling.•Soil ...age in this setting seemed to have a limited effect on C, N, and S cycling.
Carbon (C), nitrogen (N), and sulfur (S) are elements strongly influenced by biological cycling and redox reactions in soils, but few comparative analyses have investigated the behaviors of these elements with time. Thus, we examined changes in content and isotope composition of soil profiles along a chronosequence (58–212 kyr) of marine terraces on the central California coast, in an area with significant background geochemical research. Unlike in other chronosequences in more humid locations, the total C, N, and S in these soils did not vary strongly with age, possibly due to the retention of phosphorus (P). The total pools of soil N and S cannot be explained by wet deposition of NO3 and SO4 alone, suggesting other sources of atmospheric inputs such as NH4+ and dimethyl sulfide. Total C and N declined in a characteristic logarithmic pattern with depth, while S did not. The ratio of extractable soil nitrate (NO3) to total N declined with depth, suggesting strong biological demand via various avenues. In contrast, the ratio of extractable sulfate (SO4) to total S increased with depth, suggesting that S was in biological excess. We used a simple reactive transport model to integrate the depth profiles of total C and N and their isotope values. The depth trends of total concentrations suggested one-pool residence times of approximately 500 to 1000 y, consistent with turnover times calculated by mass balance. Depth trends of stable isotope values indicated that N is isotopically fractionated at a magnitude twice that of C, consistent with observed 15N-depleted nitrous oxide (N2O) emissions during the dry summer months. The isotope composition of S (total and SO4) suggests some isotope enrichment during biogeochemical cycling, but far less than observed for N. Thus, despite significant chemical weathering and elemental loss over time, the biogeochemical cycles of C, N, and S remain relatively unaffected by soil age in this climatic setting.
THE CARBON BUDGET IN SOILS Amundson, Ronald
Annual review of earth and planetary sciences,
01/2001, Letnik:
29, Številka:
1
Journal Article
Recenzirano
The global soil C reservoir, ∼1500 Gt of C (1 Gt =
10
12
kg of C), is dynamic on decadal time scales and is sensitive to
climate and human disturbance. At present, as a result of land use, soil C is ...a
source of atmospheric CO
2
in the tropics and possibly part of a sink
in northern latitudes. Here I review the processes responsible for maintaining
the global soil C reservoir and what is known about how it responds to direct
and indirect human perturbations.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Although once thought to be devoid of biology, recent studies have identified salt deposits as oases for life in the hyperarid Atacama Desert. To examine spatial patterns of microbial species and key ...nutrient sources, we genomically characterized 26 salt crusts from three sites along a fog gradient. The communities are dominated by a large variety of Halobacteriales and Bacteroidetes, plus a few algal and Cyanobacterial species. CRISPR locus analysis suggests the distribution of a single Cyanobacterial population among all sites. This is in stark contrast to the extremely high sample specificity of most other community members. Only present at the highest moisture site is a genomically characterized Thermoplasmatales archaeon (Marine Group II) and six Nanohaloarchaea, one of which is represented by a complete genome. Parcubacteria (OD1) and Saccharibacteria (TM7), not previously reported from hypersaline environments, were found at low abundances. We found no indication of a N
fixation pathway in the communities, suggesting acquisition of bioavailable nitrogen from atmospherically derived nitrate. Samples cluster by site based on bacterial and archaeal abundance patterns and photosynthetic capacity decreases with increasing distance from the ocean. We conclude that moisture level, controlled by coastal fog intensity, is the strongest driver of community membership.
•Factors of Soil Formation is experiencing an exponential increase in scientific citations.•The book, patterned on thermodynamics, reformulated ideas introduced by Dokuchaev.•The State Factor ...approach is an organizing principle for the Critical Zone research program.•The State Factor theory reveals important remaining research questions.•The least examined State Factor is humans, a glaring need for societally important issues.
The year 2021 marks the 80th anniversary of the publication of Factors of Soil Formation. A System of Quantitative Pedology by Hans Jenny. Given the exponential surge in annual citations of the book over the past 30 years, and this important milestone in its history, it is an opportune time to examine what the book presents, and how it is relevant to transdisciplinary research in the 21st Century. The book did not originate the concept of soil forming factors, which were by then already widely accepted in soil science, but instead translated it into a quantitative scientific framework through rigorous definition of the soil system, and the identification and separation of dependent and independent variables. The initial formulation of the theoretical framework was inspired by thermodynamics, but with pedologically-relevant state variables. Subsequent formulations of the model by Jenny articulated the connection and utility to examining energy and mass fluxes through the soil system, a point of departure for recent efforts to bring open system, non-equilibrium thermodynamic methods to bear on soil research. The State Factor theory is a powerful lens to examine a number of academic and societally relevant issues in the 21st century, such as the role of the biotic factor and its interplay with the physical soil environment. However, the most critical, and understudied, state factor is the effect of humans on soil systems. Earth science must embrace the challenge, and obligation to society, to explore the human footprint on the planet, and devise ways to remediate its impact.
A new view of the tree of life Hug, Laura A; Baker, Brett J; Anantharaman, Karthik ...
Nature microbiology,
04/2016, Letnik:
1
Journal Article
Recenzirano
Odprti dostop
The tree of life is one of the most important organizing principles in biology(1). Gene surveys suggest the existence of an enormous number of branches(2), but even an approximation of the full scale ...of the tree has remained elusive. Recent depictions of the tree of life have focused either on the nature of deep evolutionary relationships(3-5) or on the known, well-classified diversity of life with an emphasis on eukaryotes(6). These approaches overlook the dramatic change in our understanding of life's diversity resulting from genomic sampling of previously unexamined environments. New methods to generate genome sequences illuminate the identity of organisms and their metabolic capacities, placing them in community and ecosystem contexts(7,8). Here, we use new genomic data from over 1,000 uncultivated and little known organisms, together with published sequences, to infer a dramatically expanded version of the tree of life, with Bacteria, Archaea and Eukarya included. The depiction is both a global overview and a snapshot of the diversity within each major lineage. The results reveal the dominance of bacterial diversification and underline the importance of organisms lacking isolated representatives, with substantial evolution concentrated in a major radiation of such organisms. This tree highlights major lineages currently underrepresented in biogeochemical models and identifies radiations that are probably important for future evolutionary analyses.
PDF
