Effects of Conservation Agriculture on Soil NO Emissions and Crop Yield in Global Cereal Cropping Systems.

Conservation agriculture, which involves minimal soil disturbance, permanent soil cover, and crop rotation, has been widely adopted as a sustainable agricultural practice globally. However, the effects of conservation agriculture practices on soil NO emissions and crop yield vary based on geography, management methods, and the duration of implementation, which has hindered its widespread scientific application. In this study, we assessed the impacts of no-tillage (NT), both individually and in combination with other conservation agriculture principles, on soil NO emissions and crop yields worldwide, based on 1270 observations from 86 peer-reviewed articles.

From data to insights: Upscaling riverine GHG fluxes in Germany with machine learning.

Global fluvial ecosystems are important sources of greenhouse gases (CO, CH and NO) to the atmosphere, but their estimates are plagued by uncertainties due to unaccounted spatio-temporal variabilities in the fluxes. In this study, we tested the potential of modeling these variabilities using several machine learning models (ML) and three different input datasets (remotely sensed vegetation indices, in-situ water quality, and a combination of both) from 20 headwater catchments in Germany that differ in catchment land use and stream size. We also upscaled fluvial GHG fluxes for Germany using the best ML model and explored the role of catchment land use on the GHG spatial-temporal trends.

Divergent drivers of the spatial variation in greenhouse gas concentrations and fluxes along the Rhine River and the Mittelland Canal in Germany.

Lotic ecosystems are sources of greenhouse gases (GHGs) to the atmosphere, but their emissions are uncertain due to longitudinal GHG heterogeneities associated with point source pollution from anthropogenic activities. In this study, we quantified summer concentrations and fluxes of carbon dioxide (CO), methane (CH), nitrous oxide (NO), and dinitrogen (N), as well as several water quality parameters along the Rhine River and the Mittelland Canal, two critical inland waterways in Germany. Our main objectives were to compare GHG concentrations and fluxes along the two ecosystems and to determine the main driving factors responsible for their longitudinal GHG heterogeneities.

Characteristics of annual NH emissions from a conventional vegetable field under various nitrogen management strategies.

High N-fertilizer applications to conventional vegetable production systems are associated with substantial emissions of NH, a key substance that triggers haze pollution and ecosystem eutrophication and thus, causing considerable damage to human and ecosystem health. While N fertilization effects on NH volatilization from cereal crops have been relatively well studied, little is known about the magnitude and yield-scaled emissions of NH from vegetable systems. Here we report on a 2-year field study investigating the effect of various types and rates of fertilizer application on NH emissions and crop yields for a pepper-lettuce-cabbage rotation system in southwest China.

Integrated biochar solutions can achieve carbon-neutral staple crop production.

Agricultural food production is a main driver of global greenhouse gas emissions, with unclear pathways towards carbon neutrality. Here, through a comprehensive life-cycle assessment using data from China, we show that an integrated biomass pyrolysis and electricity generation system coupled with commonly applied methane and nitrogen mitigation measures can help reduce staple crops' life-cycle greenhouse gas emissions from the current 666.5 to -37.

Species richness is more important for ecosystem functioning than species turnover along an elevational gradient.

Many experiments have shown that biodiversity enhances ecosystem functioning. However, we have little understanding of how environmental heterogeneity shapes the effect of diversity on ecosystem functioning and to what extent this diversity effect is mediated by variation in species richness or species turnover. This knowledge is crucial to scaling up the results of experiments from local to regional scales.

Effect of vole bioturbation on NO, NO, NH, CH and CO fluxes of slurry fertilized and non-fertilized montane grassland soils in Southern Germany.

Populations of rodents such as common vole (Microtus arvalis) can develop impressive soil bioturbation activities in grasslands. These burrowing and nesting activities highly impact soil physicochemical properties as well as vegetation coverage and diversity. Managed grasslands in livestock production regions receive significant amounts of slurry, commonly at high loads at the beginning of the vegetation period.

Dynamic simulation of management events for assessing impacts of climate change on pre-alpine grassland productivity.

The productivity of permanent temperate cut grasslands is mainly driven by weather, soil characteristics, botanical composition and management. To adapt management to climate change, adjusting the cutting dates to reflect earlier onset of growth and expansion of the vegetation period is particularly important. Simulations of cut grassland productivity under climate change scenarios demands management settings to be dynamically derived from actual plant development rather than using static values derived from current management operations.

Soil type affects not only magnitude but also thermal sensitivity of NO emissions in subtropical mountain area.

It is a concern whether the effect of soil type on NO emissions has to be considered for regional mitigation strategies and emission estimates in mountainous areas with inherent spatial heterogeneities of soil type. To date, there were few field experiments which investigated soil type effects on NO emissions. Thus a 2-year field study was conducted to measure NO emissions and soil environmental variables from three different soils that were formed from similar parental rock under the same climate.

Global Research Alliance N O chamber methodology guidelines: Considerations for automated flux measurement.

Nitrous oxide (N O) emissions are highly episodic in response to nitrogen additions and changes in soil moisture. Automated gas sampling provides the necessary high temporal frequency to capture these emission events in real time, ensuring the development of accurate N O inventories and effective mitigation strategies to reduce global warming. This paper outlines the design and operational considerations of automated chamber systems including chamber design and deployment, frequency of gas sampling, and options in terms of the analysis of gas samples.

Vegetation traits of pre-Alpine grasslands in southern Germany.

The data set contains information on aboveground vegetation traits of > 100 georeferenced locations within ten temperate pre-Alpine grassland plots in southern Germany. The grasslands were sampled in April 2018 for the following traits: bulk canopy height; weight of fresh and dry biomass; dry weight percentage of the plant functional types (PFT) non-green vegetation, legumes, non-leguminous forbs, and graminoids; total green area index (GAI) and PFT-specific GAI; plant water content; plant carbon and nitrogen content (community values and PFT-specific values); as well as leaf mass per area (LMA) of PFT. In addition, a species specific inventory of the plots was conducted in June 2020 and provides plot-level information on grassland type and plant species composition.

Livestock enclosures in drylands of Sub-Saharan Africa are overlooked hotspots of NO emissions.

Sub-Saharan Africa (SSA) is home to approximately ¼ of the global livestock population, which in the last 60 years has increased by factors of 2.5-4 times for cattle, goats and sheep. An important resource for pastoralists, most livestock live in semi-arid and arid environments, where they roam during the day and are kept in enclosures (or bomas) during the night.

Substantial understory contribution to the C sink of a European temperate mountain forest landscape.

Context: The contribution of forest understory to the temperate forest carbon sink is not well known, increasing the uncertainty in C cycling feedbacks on global climate as estimated by Earth System Models.

Objectives: We aimed at quantifying the effect of woody and non-woody understory vegetation on net ecosystem production (NEP) for a forested area of 158 km in the European Alps.

Methods: We simulated C dynamics for the period 2000-2014, characterized by above-average temperatures, windstorms and a subsequent bark beetle outbreak for the area, using the regional ecosystem model LandscapeDNDC.

Earthworms offset straw-induced increase of greenhouse gas emission in upland rice production.

Increasing water scarcity and rapid socio-economic development are driving farmers in Asia to transform traditionally flooded rice cropping systems into non-flooded crop production. The management of earthworms in non-flooded rice fields appears to be a promising strategy to support residue recycling and mitigate greenhouse gas (GHG) emissions triggered by residue amendment. We conducted a field experiment on non-flooded rainfed rice fields, with and without residue amendment.

Simultaneous quantification of N , NH and N O emissions from a flooded paddy field under different N fertilization regimes.

Gaseous nitrogen (N) emissions, especially emissions of dinitrogen (N ) and ammonia (NH ), have long been considered as the major pathways of N loss from flooded rice paddies. However, no studies have simultaneously evaluated the overall response of gaseous N losses to improved N fertilization practices due to the difficulties to directly measure N emissions from paddy soils. We simultaneously quantified emissions of N (using membrane inlet mass spectrometry), NH and nitrous oxide (N O) from a flooded paddy field in southern China over an entire rice-growing season.

Climate-land-use interactions shape tropical mountain biodiversity and ecosystem functions.

Agriculture and the exploitation of natural resources have transformed tropical mountain ecosystems across the world, and the consequences of these transformations for biodiversity and ecosystem functioning are largely unknown. Conclusions that are derived from studies in non-mountainous areas are not suitable for predicting the effects of land-use changes on tropical mountains because the climatic environment rapidly changes with elevation, which may mitigate or amplify the effects of land use. It is of key importance to understand how the interplay of climate and land use constrains biodiversity and ecosystem functions to determine the consequences of global change for mountain ecosystems.

Constraining N cycling in the ecosystem model LandscapeDNDC with the stable isotope model SIMONE.

The isotopic composition (ic) of soil nitrogen (N) and, more recently, the intramolecular distribution of N in the N O molecule (site preference, SP) are powerful instruments to identify dominant N turnover processes, and to attribute N O emissions to their source processes. Despite the process information contained in the ic of N species and the associated potential for model validation, the implementation of isotopes in ecosystem models has lagged behind. To foster the validation of ecosystem models based on the ic of N species, we developed the stable isotope model for nutrient cycles (SIMONE).

Effects of climate warming on carbon fluxes in grasslands- A global meta-analysis.

Climate warming will affect terrestrial ecosystems in many ways, and warming-induced changes in terrestrial carbon (C) cycling could accelerate or slow future warming. So far, warming experiments have shown a wide range of C flux responses, across and within biome types. However, past meta-analyses of C flux responses have lacked sufficient sample size to discern relative responses for a given biome type.

Trade-offs between soil carbon sequestration and reactive nitrogen losses under straw return in global agroecosystems.

It is widely recommended that crop straw be returned to croplands to maintain or increase soil carbon (C) storage in arable soils. However, because C and nitrogen (N) biogeochemical cycles are closely coupled, straw return may also affect soil reactive N (Nr) losses, but these effects remain uncertain, especially in terms of the interactions between soil C sequestration and Nr losses under straw addition. Here, we conducted a global meta-analysis using 363 publications to assess the overall effects of straw return on soil Nr losses, C sequestration and crop productivity in agroecosystems.

Processes that determine the interplay of root exudation, methane emission and yield in rice agriculture.

Rice is the most important staple food for half of the world's population, but also accounts for about 10% of all anthropogenic CH emissions. In spite of a wealth of information on the mechanistic basis and the importance of the rice plant in mediating these emissions, the significance of root exudation for CH emissions and the processes that determine root exudation are not well understood. Root exudates derive from photosynthate allocated to the root and subjected to root anabolic and catabolic processes.

Greenhouse gas fluxes over managed grasslands in Central Europe.

Central European grasslands are characterized by a wide range of different management practices in close geographical proximity. Site-specific management strategies strongly affect the biosphere-atmosphere exchange of the three greenhouse gases (GHG) carbon dioxide (CO ), nitrous oxide (N O), and methane (CH ). The evaluation of environmental impacts at site level is challenging, because most in situ measurements focus on the quantification of CO exchange, while long-term N O and CH flux measurements at ecosystem scale remain scarce.

Impacts of climate and land use on N O and CH fluxes from tropical ecosystems in the Mt. Kilimanjaro region, Tanzania.

In this study, we quantify the impacts of climate and land use on soil N O and CH fluxes from tropical forest, agroforest, arable and savanna ecosystems in Africa. To do so, we measured greenhouse gases (GHG) fluxes from 12 different ecosystems along climate and land-use gradients at Mt. Kilimanjaro, combining long-term in situ chamber and laboratory soil core incubation techniques.

Impacts of climate and management on water balance and nitrogen leaching from montane grassland soils of S-Germany.

In this study water balance components as well as nitrogen and dissolved organic carbon leaching were quantified by means of large weighable grassland lysimeters at three sites (860, 770 and 600 m a.s.l.

Disentangling gross NO production and consumption in soil.

The difficulty of measuring gross NO production and consumption in soil impedes our ability to predict NO dynamics across the soil-atmosphere interface. Our study aimed to disentangle these processes by comparing measurements from gas-flow soil core (GFSC) and NO pool dilution (NOPD) methods. GFSC directly measures soil NO and N fluxes, with their sum as the gross NO production, whereas NOPD involves addition of NO into a chamber headspace and measuring its isotopic dilution over time.