Soil carbon sequestration in global working lands as a gateway for negative emission technologies.

The ongoing climate crisis merits an urgent need to devise management approaches and new technologies to reduce atmospheric greenhouse gas concentrations (GHG) in the near term. However, each year that GHG concentrations continue to rise, pressure mounts to develop and deploy atmospheric CO removal pathways as a complement to, and not replacement for, emissions reductions. Soil carbon sequestration (SCS) practices in working lands provide a low-tech and cost-effective means for removing CO from the atmosphere while also delivering co-benefits to people and ecosystems.

Anthropogenic degradation alter surface soil biogeochemical pools and microbial communities in an Andean temperate forest.

Soil microbial communities regulate a myriad of critical biogeochemical functions in forest ecosystems. Anthropogenic disturbances in natural forests could drive major shifts in plant and microbial communities resulting in substantial biogeochemical alterations. We evaluated the effect of anthropogenic disturbances in the soils of Andean temperate forests with different levels of degradation: i) mature forest (MF), ii) secondary forest (SF), iii) degraded forest (DF), and iv) deforested site converted into a prairie (DP).

Soil-derived Nature's Contributions to People and their contribution to the UN Sustainable Development Goals.

This special issue provides an assessment of the contribution of soils to Nature's Contributions to People (NCP). Here, we combine this assessment and previously published relationships between NCP and delivery on the UN Sustainable Development Goals (SDGs) to infer contributions of soils to the SDGs. We show that in addition to contributing positively to the delivery of all NCP, soils also have a role in underpinning all SDGs.

Role of soil in the regulation of human and plant pathogens: soils' contributions to people.

Soil and soil biodiversity play critical roles in Nature's Contributions to People (NCP) # 10, defined as Nature's ability to regulate direct detrimental effects on humans, and on human-important plants and animals, through the control or regulation of particular organisms considered to be harmful. We provide an overview of pathogens in soil, focusing on human and crop pathogens, and discuss general strategies, and examples, of how soils' extraordinarily diverse microbial communities regulate soil-borne pathogens. We review the ecological principles underpinning the regulation of soil pathogens, as well as relationships between pathogen suppression and soil health.

Impact of biochar on plant growth and uptake of ciprofloxacin, triclocarban and triclosan from biosolids.

Application of municipal biosolids in agriculture present a concern with potential uptake and bioaccumulation of pharmaceutical compounds from biosolids into agronomic plants. We evaluated the efficacy of biochar as a soil amendment to minimize uptake of antimicrobial agents (ciprofloxacin, triclocarban, and triclosan) in lettuce () and carrot () plants. Biochar reduced the concentration of ciprofloxacin and triclocarban in lettuce leaves and resulted in a 67% reduction of triclosan in carrot roots.

Impact of Irrigation Strategies on Tomato Root Distribution and Rhizosphere Processes in an Organic System.

Root exploitation of soil heterogeneity and microbially mediated rhizosphere nutrient transformations play critical roles in plant resource uptake. However, how these processes change under water-saving irrigation technologies remains unclear, especially for organic systems where crops rely on soil ecological processes for plant nutrition and productivity. We conducted a field experiment and examined how water-saving subsurface drip irrigation (SDI) and concentrated organic fertilizer application altered root traits and rhizosphere processes compared to traditional furrow irrigation (FI) in an organic tomato system.

Rapid elimination of foodborne and environmental fungal contaminants by benzo analogs.

Background: Contamination of food or the environment by fungi, especially those resistant to conventional fungicides or drugs, represents a hazard to human health. The objective of this study is to identify safe, natural antifungal agents that can remove fungal pathogens or contaminants rapidly from food and / or environmental sources.

Results: Fifteen antifungal compounds (nine benzo derivatives as candidates; six conventional fungicides as references) were investigated.

A world of co-benefits: Solving the global nitrogen challenge.

Nitrogen is a critical component of the economy, food security, and planetary health. Many of the world's sustainability targets hinge on global nitrogen solutions, which, in turn, contribute lasting benefits for: (i) world hunger; (ii) soil, air and water quality; (iii) climate change mitigation; and (iv) biodiversity conservation. Balancing the projected rise in agricultural nitrogen demands while achieving these 21 century ideals will require policies to coordinate solutions among technologies, consumer choice, and socioeconomic transformation.

Yields and resilience outcomes of organic, cover crop, and conventional practices in a Mediterranean climate.

Adaptive management practices that maximize yields while improving yield resilience are required in the face of resource variability and climate change. Ecological intensification such as organic farming and cover cropping are lauded in some studies for fostering yield resilience, but subject to criticism in others for their low productivity. We implemented a quantitative framework to assess yield resilience, emphasizing four aspects of yield dynamics: yield, yield stability, yield resistance (i.

Deep soil inventories reveal that impacts of cover crops and compost on soil carbon sequestration differ in surface and subsurface soils.

Increasing soil organic carbon (SOC) via organic inputs is a key strategy for increasing long-term soil C storage and improving the climate change mitigation and adaptation potential of agricultural systems. A long-term trial in California's Mediterranean climate revealed impacts of management on SOC in maize-tomato and wheat-fallow cropping systems. SOC was measured at the initiation of the experiment and at year 19, at five depth increments down to 2 m, taking into account changes in bulk density.

Long-term use of cover crops and no-till shift soil microbial community life strategies in agricultural soil.

Reducing tillage and growing cover crops, widely recommended practices for boosting soil health, have major impacts on soil communities. Surprisingly little is known about their impacts on soil microbial functional diversity, and especially so in irrigated Mediterranean ecosystems. In long-term experimental plots at the West Side Research and Extension Center in California's Central Valley, we characterized soil microbial communities in the presence or absence of physical disturbance due to tillage, in the presence or absence of cover crops, and at three depths: 0-5, 5-15 and 15-30 cm.

The century experiment: the first twenty years of UC Davis' Mediterranean agroecological experiment.

The Century Experiment at the Russell Ranch Sustainable Agriculture Facility at the University of California, Davis provides long-term agroecological data from row crop systems in California's Central Valley starting in 1993. The Century Experiment was initially designed to study the effects of a gradient of water and nitrogen availability on soil properties and crop performance in ten different cropping systems to measure tradeoffs and synergies between agricultural productivity and sustainability. Currently systems include 11 different cropping systems-consisting of four different crops and a cover crop mixture-and one native grass system.

Use of nuclear receptor luciferase-based bioassays to detect endocrine active chemicals in a biosolids-biochar amended soil.

Biosolids are a potentially valuable source of carbon and nutrients for agricultural soils; however, potential unintended impacts on human health and the environment must be considered. Virtually all biosolids contain trace amounts endocrine-disrupting chemicals derived from human use of pharmaceuticals and personal care products (PPCPs). One potential way to reduce the bioavailability of PPCPs is to co-apply biosolids with biochar to soil, because biochar's chemical (e.

Effect of benzene and ethylbenzene on the transcription of methyl-tert-butyl ether degradation genes of Methylibium petroleiphilum PM1.

Methyl-tert-butyl ether (MTBE) and its degradation by-product, tert-butyl alcohol (TBA), are widespread contaminants detected frequently in groundwater in California. Since MTBE was used as a fuel oxygenate for almost two decades, leaking underground fuel storage tanks are an important source of contamination. Gasoline components such as BTEX (benzene, toluene, ethylbenzene and xylenes) are often present in mixtures with MTBE and TBA.

Impact of biochar amendment on soil water soluble carbon in the context of extreme hydrological events.

Biochar amendments to soil have been promoted as a low cost carbon (C) sequestration strategy as well as a way to increase nutrient retention and remediate contaminants. If biochar is to become part of a long-term management strategy, it is important to consider its positive and negative impacts, and their trade-offs, on soil organic matter (SOM) and soluble C under different hydrological conditions such as prolonged drought or frequent wet-dry cycles. A 52-week incubation experiment measuring the influence of biochar on soil water soluble C under different soil moisture conditions (wet, dry, or wet-dry cycles) indicated that, in general, dry and wet-dry cycles increased water soluble C, and biochar addition further increased release of water soluble C from native SOM.

Shamba Maisha: randomized controlled trial of an agricultural and finance intervention to improve HIV health outcomes.

Objectives: Food insecurity and HIV/AIDS outcomes are inextricably linked in sub-Saharan Africa. We report on health and nutritional outcomes of a multisectoral agricultural intervention trial among HIV-infected adults in rural Kenya.

Design: This is a pilot cluster randomized controlled trial.

Phenylurea herbicide sorption to biochars and agricultural soil.

Biochar is increasingly been used as a soil amendment to improve water-holding capacity, reduce nutrient leaching, increase soil pH, and also as a means to reduce contamination through sorption of heavy metals or organic pollutants. The sorption behavior of three phenylurea herbicides (monuron, diuron and linuron) on five biochars (Enhanced Biochar, Hog Waste, Turkey Litter, Walnut Shell and Wood Feedstock) and an agricultural soil (Yolo silt loam) was investigated using a batch equilibration method. Sorption isotherms of herbicides to biochars were well described by the Freundlich model (R(2) = 0.

Shamba Maisha: Pilot agricultural intervention for food security and HIV health outcomes in Kenya: design, methods, baseline results and process evaluation of a cluster-randomized controlled trial.

Background: Despite advances in treatment of people living with HIV, morbidity and mortality remains unacceptably high in sub-Saharan Africa, largely due to parallel epidemics of poverty and food insecurity.

Methods/design: We conducted a pilot cluster randomized controlled trial (RCT) of a multisectoral agricultural and microfinance intervention (entitled Shamba Maisha) designed to improve food security, household wealth, HIV clinical outcomes and women's empowerment. The intervention was carried out at two HIV clinics in Kenya, one randomized to the intervention arm and one to the control arm.

Gene mdpC plays a regulatory role in the methyl-tert-butyl ether degradation pathway of Methylibium petroleiphilum strain PM1.

Among the few bacteria known to utilize methyl tert-butyl ether (MTBE) as a sole carbon source, Methylibium petroleiphilum PM1 is a well-characterized organism with a sequenced genome; however, knowledge of the genetic regulation of its MTBE degradation pathway is limited. We investigated the role of a putative transcriptional activator gene, mdpC, in the induction of MTBE-degradation genes mdpA (encoding MTBE monooxygenase) and mdpJ (encoding tert-butyl alcohol hydroxylase) of strain PM1 in a gene-knockout mutant mdpC(-). We also utilized quantitative reverse transcriptase PCR assays targeting genes mdpA, mdpJ and mdpC to determine the effects of the mutation on transcription of these genes.

Impacts of an ethanol-blended fuel release on groundwater and fate of produced methane: Simulation of field observations.

In a field experiment at Vandenberg Air Force Base (VAFB) designed to mimic the impact of a small-volume release of E10 (10% ethanol and 90% conventional gasoline), two plumes were created by injecting extracted groundwater spiked with benzene, toluene, and -xylene, abbreviated BTX (No-Ethanol Lane) and BTX plus ethanol (With-Ethanol Lane) for 283 days. We developed a reactive transport model to understand processes controlling the fate of ethanol and BTX. The model was calibrated to the extensive field dataset and accounted for concentrations of sulfate, iron, acetate, and methane along with iron-reducing bacteria, sulfate-reducing bacteria, fermentative bacteria, and methanogenic archaea.

Effect of different transport observations on inverse modeling results: case study of a long-term groundwater tracer test monitored at high resolution.

Conservative tracer experiments can provide information useful for characterizing various subsurface transport properties. This study examines the effectiveness of three different types of transport observations for sensitivity analysis and parameter estimation of a three-dimensional site-specific groundwater flow and transport model: conservative tracer breakthrough curves (BTCs), first temporal moments of BTCs (), and tracer cumulative mass discharge () through control planes combined with hydraulic head observations (). High-resolution data obtained from a 410-day controlled field experiment at Vandenberg Air Force Base, California (USA), have been used.

Effects of triclosan and biosolids on microbial community composition in an agricultural soil.

Triclosan (TCS) is a widely used antimicrobial agent found at high concentrations in biosolids produced during municipal wastewater treatment. The effect of adding TCS, in the presence or absence of biosolids, on the composition of an agricultural soil microbial community was measured using phospholipid fatty acid analysis (PLFA). Most changes observed in microbial community composition were attributable to the addition of biosolids or to the passage of time, with smaller changes due to TCS exposure, regardless of the presence of biosolids.