Assessing availability and greenhouse gas emissions of lignocellulosic biomass feedstock supply – case study for a catchment in England

© 2019 Society of Chemical Industry and John Wiley & Sons, Ltd.Feedstocks from lignocellulosic biomass (LCB) include crop residues and dedicated per¬ennial biomass crops. The latter are often considered superior in terms of climate change mitigation potential. Uncertainty remains over their availability as feedstocks for biomass provision and the net greenhouse gas emissions (GHG) during crop production. Our objective was to assess the optimal land allocation to wheat and Miscanthus in a specific case study located in England, to increase bio¬mass availability, improve the carbon balance (and reduce the consequent GHG emissions), and mini¬mally constrain grain production losses from wheat. Using soil and climate variables for a catchment in east England, biomass yields and direct nitrogen emissions were simulated with validated process-based models. A ‘Field to up-stream factory gate’ life-cycle assessment was conducted to estimate indirect management-related GHG emissions. Results show that feedstock supply from wheat straw can be supplemented beneficially with LCB from Miscanthus grown on selected low-quality soils. In our study, 8% of the less productive arable land area was dedicated to Miscanthus, increasing total LCB provision by about 150%, with a 52% reduction in GHG emission per ton LCB delivered and only a minor effect on wheat grain production (−3%). In conclusion, even without considering the likely carbon sequestration in impoverished soils, agriculture should embrace the opportunities to provide the bioeconomy with LCB from dedicated, perennial crops.Peer reviewe

Re-assessing Nitrous Oxide Emissions from Croplands Across Mainland China

Reliable quantification of nitrous oxide emission is a key to assessing efficiency of use and environmental impacts of N fertilizers in crop production. In this study, N2O emission and yield were quantified with a database of 853 field measurements in 104 reported studies and a regression model was fitted to the associated environmental attributes and management practices from China’s croplands. The fitted emission model explained 48% of the variance in N2O emissions as a function of fertilizer rate, crop type, temperature, soil clay content, and the interaction between N rate and fertilizer type. With all other variables fixed, N2O emissions were lower with rice than with legumes and then other upland crops, lower with organic fertilizers than with mineral fertilizers. We used the subset of the dataset for rice - covering a full range of different typical water regimes, and estimated emissions from China’s rice cultivation to be 31.1 Gg N2O-N per year. The fitted yield model explained 35% of the variance in crop yield as a function of fertilizer rate, temperature, crop type, and soil clay content. Finally, the empirical models for N2O emission and crop yield were coupled to explore the optimum N rates (N rate with minimum N2O emission per unit yield) for combinations of crop and fertilizer types. Consequently, the optimum N application rate ranged between 100 kg N ha−1 and 190 kg N ha−1 respectively with organic and mineral fertilizers, and different crop types. This study therefore improved on existing empirical methods to estimate N2O emissions from China’s croplands and suggests how N rate may be optimized for different crops, fertilizers and site conditions

Impact of extreme weather events frequency and intensity in shaping phytoplankton communities

Lake habitats and communities can often be correlated with general morphometric and geographic characteristics such as depth, latitude, altitude, or watershed area. Further, communities are typically correlated with average environmental conditions such as seasonal temperature and nutrient levels. The frequency and intensity of extreme weather events (rain and wind) are typically not encompassed by average environmental descriptors, yet, can modify the physical habitats of lakes, significantly influencing phytoplankton growth and survival. We tested the hypothesis that lakes with a higher frequency and intensity of extreme weather events have a functionally different phytoplankton assemblage from lakes with a lower frequency of extreme weather events. We compiled long-term (mean = 20±13 years, range 0.6-44 years) phytoplankton datasets for 22 lakes across a wide gradient of altitude, latitude, depth, and trophic state. We classified the phytoplankton genera into morpho-functional groups and C-S-R strategists, and compared among lake phytoplankton assemblages’ characteristics across the gradient of wind and rain conditions experienced by the lakes. We discuss how the frequency of extreme weather events can affect phytoplankton functional groups, the dominance of differing life history strategies and ultimately community structure. The frequency and intensity of extreme events is expected to increase with climate change, with the potential to drive shifts in phytoplankton composition

A global dataset on weather, lake physics, and phytoplankton dynamics

We compiled data from over 30 lakes across the globe to address how storms influence thermal structure and phytoplankton community dynamics mediated by lake conditions and functional traits. In addition to (generally) fortnightly phytoplankton samples (mean ± SD temporal coverage across all lakes = 20 ± 13 years), the dataset includes limnological variables from standard long-term monitoring programs (24 ± 15 years coverage), daily weather observations (16 ± 10 years coverage) and, when available, high-frequency lake water temperature and water chemistry profiles (12 ± 7 years coverage). All data have been standardized to similar formats and include complete metadata. We used the dataset to develop an R-package (“algaeClassify”), which assigns phytoplankton genus/species information to multiple functional trait groups, and here we provide a summary of ongoing research using the dataset to investigate: 1) the influence of storm events on seasonal phytoplankton succession, 2) the impact of storms on lake thermal structure, and 3) whether lake phytoplankton communities are shaped by long-term patterns in disturbance frequency and intensity. We give an overview on how to access these data, and we further highlight the opportunities the dataset provides for asking both basic and applied questions in limnology, ecology, climate change, and lake management

Quantifying pelagic phosphorus regeneration using three methods in lakes of varying productivity

Phosphorus (P) is often a limiting nutrient in freshwater ecosystems, and understanding P dynamics in lakes is critical for eutrophication management. Pelagic P regeneration can support a large fraction of primary production in stratified freshwaters. Various techniques have been used to quantify pelagic P regeneration including (1) P mass balance supply–demand, (2) regression using total P as a predictor, and, more recently, (3) whole-lake metabolism calculated from high-frequency dissolved oxygen (DO) data. To our knowledge no study comparing these methods in multiple lakes has been performed. To compare these 3 approaches, we investigated 3 Global Lake Ecological Observatory Network (GLEON) lakes that differ in productivity: Acton, a Midwestern USA hypereutrophic reservoir; and 2 Northeastern USA glacial lakes, oligotrophic Giles and mesotrophic/dystrophic Lacawac. In Acton, we used all 3 methods, but for Giles and Lacawac we used only the total P regression and metabolism techniques. Our results show the best agreement among methods in the mesotrophic lake, whereas the metabolism approach underestimated regeneration in the oligotrophic lake and overestimated regeneration in the hypereutrophic reservoir compared with other methods. P regeneration rates for the hypereutrophic reservoir were the most sensitive to the metabolism-based input parameters. Our study illustrates a novel use of high-frequency DO data, which are commonly collected on many GLEON buoys, to understand lake nutrient dynamics

Results from the fertilizer demonstration experiment with maize at Farm for the Future Tanzania in Iringa, in 2020

In 2020, an experiment was run for the third consecutive season at the Farm for the Future Tanzania Ltd. (FFF), which is part of Ilula Orphan Program’s (IOP) Farm, Ilula, Iringa Region, in Tanzania. The FFF farm is training farmers in 16 villages with a focus on dissemination activities at regional and national levels. The purpose of the experiment is to test and demonstrate crop fertilization strategies that combine high maize yields with high nutrient use efficiency (NUE) and low greenhouse gas (GHG) emissions. Five nutrient management treatments were combined in a full factorial setup with two tillage options. Highest yields were obtained with reduced tillage combined with NPK fertilizer to target 70% of waterlimited yield (Yw) and micro-nutrients (Mg, S, Zn combined), and with half NPK fertilizer and half composted manure. The lowest maize yields were obtained from both the treatment without fertilizer application and the fertilizer treatment with only P and K applied at reduced and conventional tillage. Results showed no significant differences in both agronomic N use efficiency (N-AE, additional grain yield per kg N applied when correcting for the P and K applied) and fertilizer use efficiency (additional grain yield per kg N applied when including yield effects from P and K) between reduced and conventional tillage. N-AE obtained in the experiment of 34.0 kg yield/kg N was much higher compared to the current average N-AE in sub-Saharan Africa of 14.3 kg yield/kg N. When targeting 70% of Yw for maize, this improved N-AE value could result in 58% reduction in GHG emission per hectare (ha) from fertilizer application (direct and indirect emissions). Despite the cancellation of the farmers field days, due to the Covid19 pandemic, ten young farmers still took part in the experimental setup and trial planting

Results from the fertilizer demonstration experiment with maize at Farm for the Future Tanzania in Iringa, in 2021: Final narrative report

In 2021, an experiment was run for the fourth consecutive season at the Farm for the Future Tanzania Ltd (FFF) which is part of Ilula Orphan Program (IOP)’s Farm, Ilula, Iringa Region, in Tanzania. The FFF farm, is training farmers in 16 villages, with a focus on dissemination activities at regional, as well as national level. The purpose of the experiment is to experimentally test and demonstrate low-emission crop fertilisation strategies that combine high maize yields with high nutrient use efficiency and low emissions. Four nutrient management treatments were combined in a full factorial setup with two tillage options. Lowest yields were obtained with no fertilizer addition (control treatment) under conventional tillage and reduced tillage (1-2 t/ha), while the treatments with fertilizer addition consistently showed very high yields (close to 10 t/ha). Root number and root length were larger for reduced tillage compared to conventional tillage at the control treatment, but this difference was not significant. Root penetration resistance was significantly higher at conventional tillage compared to reduced tillage for the control treatment. Around 100 pupils from primary as well as secondary school made two field visits to the trial. Also, a farmers field day was organized, and from the sixteen villages surrounding the farm, a total of about 400 farmers attended the planting session and the field day

Training macrosystems scientists requires both interpersonal and technical skills

Macrosystems science strives to integrate patterns and processes that span regional to continental scales. The scope of such research often necessitates the involvement of large interdisciplinary and/or multi-institutional teams composed of scientists across a range of career stages, a diversity that requires researchers to hone both technical and interpersonal skills. We surveyed participants in macrosystems projects funded by the US National Science Foundation to assess the perceived importance of different skills needed in their research, as well as the types of training they received. Survey results revealed a mismatch between the skills participants perceive as important and the training they received, particularly for interpersonal and management skills. We highlight lessons learned from macrosystems training case studies, explore avenues for further improvement of undergraduate and graduate education, and discuss other training opportunities for macrosystems scientists. Given the trend toward interdisciplinary research beyond the macrosystems community, these insights are broadly applicable for scientists involved in diverse, collaborative projects.https://esajournals.onlinelibrary.wiley.com/doi/full/10.1002/fee.228

Current water quality guidelines across North America and Europe do not protect lakes from salinization

Human-induced salinization caused by the use of road deicing salts, agricultural practices, mining operations, and climate change is a major threat to the biodiversity and functioning of freshwater ecosystems. Yet, it is unclear if freshwater ecosystems are protected from salinization by current water quality guidelines. Leveraging an experimental network of land-based and in-lake mesocosms across North America and Europe, we tested how salinization-indicated as elevated chloride (C-) concentration-will affect lake food webs and if two of the lowest Cl- thresholds found globally are sufficient to protect these food webs. Our results indicated that salinization will cause substantial zooplankton mortality at the lowest Cl- thresholds established in Canada (120 mg Cl-/L) and the United States (230 mg Cl-/L) and throughout Europe where Cl- thresholds are generally higher. For instance, at 73% of our study sites, Cl- concentrations that caused a >= 50% reduction in cladoceran abundance were at or below Cl thresholds in Canada, in the United States, and throughout Europe. Similar trends occurred for copepod and rotifer zooplankton. The loss of zooplankton triggered a cascading effect causing an increase in phytoplankton biomass at 47% of study sites. Such changes in lake food webs could alter nutrient cycling and water clarity and trigger declines in fish production. Current Cl- thresholds across North America and Europe clearly do not adequately protect lake food webs. Water quality guidelines should be developed where they do not exist, and there is an urgent need to reassess existing guidelines to protect lake ecosystems from human-induced salinization.Peer reviewe