【增温对土壤剖面碳通量的影响】Caitlin E. Hicks Pries, C. Castanha, R.C. Porras, M.S. Torn. The whole-soil carbon flux in response to warming. Science 31 Mar 2017: Vol. 355, Issue 6332, pp. 1420-1423 DOI: 10.1126/science.aal1319
Abstract
Soil organic carbon harbors three times as much carbon as Earth’s atmosphere, and its decomposition is a potentially large climate change feedback and major source of uncertainty in climate projections. The response of whole-soil profiles to warming has not been tested in situ. In a deep warming experiment in mineral soil, we found that CO2 production from all soil depths increased with 4°C warming; annual soil respiration increased by 34 to 37%. All depths responded to warming with similar temperature sensitivities, driven by decomposition of decadal-aged carbon. Whole-soil warming reveals a larger soil respiration response than many in situ experiments (most of which only warm the surface soil) and models.
【国际食品贸易中的地下水损耗】Carole Dalin, Yoshihide Wada, Thomas Kastner & Michael J. Puma. Groundwater depletion embedded in international food trade. Nature 543, 700–704 (30 March 2017) doi:10.1038/nature21403
Abstract
Recent hydrological modelling1 and Earth observations2, 3 have located and quantified alarming rates of groundwater depletion worldwide. This depletion is primarily due to water withdrawals for irrigation1, 2, 4, but its connection with the main driver of irrigation, global food consumption, has not yet been explored. Here we show that approximately eleven per cent of non-renewable groundwater use for irrigation is embedded in international food trade, of which two-thirds are exported by Pakistan, the USA and India alone. Our quantification of groundwater depletion embedded in the world’s food trade is based on a combination of global, crop-specific estimates of non-renewable groundwater abstraction and international food trade data. A vast majority of the world’s population lives in countries sourcing nearly all their staple crop imports from partners who deplete groundwater to produce these crops, highlighting risks for global food and water security. Some countries, such as the USA, Mexico, Iran and China, are particularly exposed to these risks because they both produce and import food irrigated from rapidly depleting aquifers. Our results could help to improve the sustainability of global food production and groundwater resource management by identifying priority regions and agricultural products at risk as well as the end consumers of these products.
【气候变化对美国农业总生产力的影响】Xin-Zhong Lianga,b,1, You Wuc,b, Robert G. Chambersd,1, Daniel L. Schmoldte, Wei Gaof,g,1, Chaoshun Liuh,i, Yan-An Liuh,i, Chao Suna, and Jennifer A. Kennedyb. Determining climate effects on US total agricultural productivity. PNAS, doi: 10.1073/pnas.1615922114
Abstract
The sensitivity of agricultural productivity to climate has not been sufficiently quantified. The total factor productivity (TFP) of the US agricultural economy has grown continuously for over half a century, with most of the growth typically attributed to technical change. Many studies have examined the effects of local climate on partial productivity measures such as crop yields and economic returns, but these measures cannot account for national-level impacts. Quantifying the relationships between TFP and climate is critical to understanding whether current US agricultural productivity growth will continue into the future. We analyze correlations between regional climate variations and national TFP changes, identify key climate indices, and build a multivariate regression model predicting the growth of agricultural TFP based on a physical understanding of its historical relationship with climate. We show that temperature and precipitation in distinct agricultural regions and seasons explain ∼70% of variations in TFP growth during 1981–2010. To date, the aggregate effects of these regional climate trends on TFP have been outweighed by improvements in technology. Should these relationships continue, however, the projected climate changes could cause TFP to drop by an average 2.84 to 4.34% per year under medium to high emissions scenarios. As a result, TFP could fall to pre-1980 levels by 2050 even when accounting for present rates of innovation. Our analysis provides an empirical foundation for integrated assessment by linking regional climate effects to national economic outcomes, offering a more objective resource for policy making.
【根际微生物群协调植物营养和免疫】Gabriel Castrillo, Paulo José Pereira Lima Teixeira, Sur Herrera Paredes, Theresa F. Law, Laura de Lorenzo, Meghan E. Feltcher, Omri M. Finkel, Natalie W. Breakfield, Piotr Mieczkowski, Corbin D. Jones, Javier Paz-Ares & Jeffery L. Dangl. Root microbiota drive direct integration of phosphate stress and immunity. Nature 543, 513–518 (23 March 2017) doi:10.1038/nature21417
Abstract
Plants live in biogeochemically diverse soils with diverse microbiota. Plant organs associate intimately with a subset of these microbes, and the structure of the microbial community can be altered by soil nutrient content. Plant-associated microbes can compete with the plant and with each other for nutrients, but may also carry traits that increase the productivity of the plant. It is unknown how the plant immune system coordinates microbial recognition with nutritional cues during microbiome assembly. Here we establish that a genetic network controlling the phosphate stress response influences the structure of the root microbiome community, even under non-stress phosphate conditions. We define a molecular mechanism regulating coordination between nutrition and defence in the presence of a synthetic bacterial community. We further demonstrate that the master transcriptional regulators of phosphate stress response in Arabidopsis thaliana also directly repress defence, consistent with plant prioritization of nutritional stress over defence. Our work will further efforts to define and deploy useful microbes to enhance plant performance.
【一项氮肥高效利用计划】Xin Zhang. Biogeochemistry: A plan for efficient use of nitrogen fertilizers. Nature 543, 322–323 (16 March 2017) doi:10.1038/543322a
A global analysis finds that nitrogen fertilizers could be used more efficiently if their international distribution across croplands was altered — a measure that would also decrease nitrogen pollution.
