Contribution of different cover crop species to soil organic matter fractions and N2O emissions under Norwegian cereal production

In Norway, cover crops were introduced to prevent loss of nitrogen and phosphorous from fields to waterways. Today, cover crops are also used to restore soil organic matter and improve soil health. Yet, the direction and magnitude of these effects are variable, and little is known about the persistence of the C derived from the cover crops in the soil. In the CAPTURE project, we evaluated the soil C sequestration potential from different cover crops used in the main cereal production areas in Norway. To do so, we used pulse labelling with 13C (CO2) to label four different cover crop species Italian ryegrass, phacelia, oilseed radish and summer vetch through their growing period. Cover crops were grown in a monoculture to enable the labelling. The results of the first year of the experiment show that cover crops produced 10- 14 Mg ha-1 above ground biomass, corresponding to 4-6 Mg C ha-1. At the end of the growing season, 3-5% of cover crop C was found in the soil particulate organic matter (POM) fraction and 2-4% in the soil mineral organic matter fraction (MAOM). In the following years, the fate of C derived from the cover crops in the soil will be determined. Furthermore, the soil C sequestration of the different cover crops will be scaled to barley plots in the same experiment, to which cover crops had been undersown in spring or summer. In these plots, N2O emissions have been measured through the whole year. The greenhouse gas trade-offs of cover crops in Norwegian cereal production will be estimated

Meta-analysis of type 2 Diabetes in African Americans Consortium

Type 2 diabetes (T2D) is more prevalent in African Americans than in Europeans. However, little is known about the genetic risk in African Americans despite the recent identification of more than 70 T2D loci primarily by genome-wide association studies (GWAS) in individuals of European ancestry. In order to investigate the genetic architecture of T2D in African Americans, the MEta-analysis of type 2 DIabetes in African Americans (MEDIA) Consortium examined 17 GWAS on T2D comprising 8,284 cases and 15,543 controls in African Americans in stage 1 analysis. Single nucleotide polymorphisms (SNPs) association analysis was conducted in each study under the additive model after adjustment for age, sex, study site, and principal components. Meta-analysis of approximately 2.6 million genotyped and imputed SNPs in all studies was conducted using an inverse variance-weighted fixed effect model. Replications were performed to follow up 21 loci in up to 6,061 cases and 5,483 controls in African Americans, and 8,130 cases and 38,987 controls of European ancestry. We identified three known loci (TCF7L2, HMGA2 and KCNQ1) and two novel loci (HLA-B and INS-IGF2) at genome-wide significance (4.15 × 10(-94)<P<5 × 10(-8), odds ratio (OR)  = 1.09 to 1.36). Fine-mapping revealed that 88 of 158 previously identified T2D or glucose homeostasis loci demonstrated nominal to highly significant association (2.2 × 10(-23) < locus-wide P<0.05). These novel and previously identified loci yielded a sibling relative risk of 1.19, explaining 17.5% of the phenotypic variance of T2D on the liability scale in African Americans. Overall, this study identified two novel susceptibility loci for T2D in African Americans. A substantial number of previously reported loci are transferable to African Americans after accounting for linkage disequilibrium, enabling fine mapping of causal variants in trans-ethnic meta-analysis studies.Peer reviewe

CAPTURE- Assessment of cover cropping as climate action in cereal production in Norway

Recently, the role of cover crops in agriculture has broadened due to their ecosystem services and their potential as a climate mitigation tool via carbon sequestration. However, their net climate effect from carbon sequestration may be offset by nitrate leaching and nitrous oxide (N2O) emissions when plant residues decompose in the soil. In CAPTURE (a 3-year project funded by the Agriculture and Food Industry Research Funds), we evaluate the net climate effect of different cover crops in the main cereal production areas in South and Mid-Norway. To determine the soil carbon sequestration potential from different cover crops, four species (Italian ryegrass, phacelia, oilseed radish and summer vetch) were planted in monoculture (in 4 replicates) in spring 2021 and pulse labelled (5-6 pulses) with 13CO2 during the growing season in 1 m3 transparent chambers. Shortly after the last pulse, biomass (above- and belowground) and soil samples were collected and brought to the laboratory for processing. These samples are now under analysis and together with consecutive samplings in 2022 we will determine the input of cover crop-derived carbon (13C) to the soil. These data will also be used to feed a model to evaluate the potential for long-term carbon storage of different cover-crops. Moreover, we will investigate the fate and persistence of this carbon input, by assessing how much of the 13C was retained as particulate organic matter (POM) and as mineral-associated organic matter (MAOM). The fate of soil organic matter -13C in each fraction will be monitored in the following years. To study the contribution of shoot- versus root biomass to carbon sequestration, we established microplots in which aboveground biomass was exchanged and incorporated reciprocally between the labelled microplot and an equivalent unlabelled microplot with the same cover crop. In this way, each field replicate includes one microplot with labelled shoots and unlabelled roots and another microplot with unlabelled shoots and labelled roots, which will be sampled and analysed in 2022. Cover crop-specific carbon sequestration will be scaled to barley plots in the same experiment, to which cover crops had been undersown in spring or summer 2021. In these plots, N2O emissions have been quantified weekly throughout the growing period and more frequently during autumn and winter, which should allow us to estimate greenhouse gas trade-offs of cover crops in Norwegian cereal production and contribute to improve the national greenhouse gas inventory

CN-SIM - a model for the turnover of soil organic mattter. II: Short term carbon and nitrogen development

A computer model is presented, which describes the transformations of C and N in the soil. The development has been divided into two interdependent tasks, the first being development of long-term SOC simulation capabilities, and the second being short-term simulations of C and N, as described in this paper. A number of existing, independent laboratory experiments, covering a range of amendments, have been used for this task. The amendments includes a variety of different crop residues and animal manure. These experiments have included measurements of 13C, 14C and 15N in various pools, and the model facilitates the simulation of these isotopes. Non-linear, automated optimisation procedures were utilised wherever feasible. The model generally yielded good descriptions of the measured data. A new method for subdividing the added matter was developed, which gave results generally superior to subdivision according to van Soest pools

Near-infra-red spectroscopy (NIR) for characterisation of plant residue quality - A new approach for predicting decomposition and nitrogen release in agricultural soils

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Analysis of Functional MRI Data Using Mutual Information

. A new information-theoretic approach is presented for analyzing fMRI data to calculate the brain activation map. The method is based on a formulation of the mutual information between two waveforms-- the fMRI temporal response of a voxel and the experimental protocol timeline. Scores based on mutual information are generated for all voxels and then used to compute the activation map of an experiment. Mutual information for fMRI analysis is employed because it has been shown to be robust in quantifying the relationship between any two waveforms. More importantly, our technique takes a principled approach toward calculating the brain activation map by making few assumptions about the relationship between the protocol timeline and the temporal response of a voxel. This is important especially in fMRI experiments where little is known about the relationship between these two waveforms. Experiments are presented to demonstrate this approach of computing the brain activation ..

Criteria for describing decomposition of plant materials in a dynamic simulation model

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