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Promoting the bioeconomy to aid in the achievement of sustainability goals has increased demand for biomass as feedstock. Residual biomass from agricultural production is an attractive option, as it is a by‐product that does not compete with food production. However, crop residues are important for the preservation of soil quality, especially for the maintenance of soil organic carbon. Therefore, their use can conflict with environmental goals and initiatives that aim to preserve soil fertility and carbon stocks. Nevertheless, the adoption of intermediate crops could compensate for the negative effects of crop residue removal. Moreover, if crop residues are used for a bioeconomy pathway such as biogas production, the resulting digestate derived from the anaerobic digestion process could be returned to the soil, providing an input of highly recalcitrant carbon. In this study, we modeled the effects of removal of crop residues, the cultivation of intermediate crops, and the application of digestate on Swedish soil organic carbon stocks. Our results suggest that the inclusion of intermediate crops could raise the carbon stocks at equilibrium by an average of 1.93 t C ha−1 (~3% increase) with a notable spatial variation. Digestate application showed a higher average increase (3.3 t C ha−1, ~5%) with an even higher variation. The removal of crop residues was detrimental in some areas, resulting in a loss of carbon, which could not be compensated for entirely by the introduction of intermediate crops or digestate recycling. Combining these two practices showed overall positive effects on soil organic carbon stocks; however, the results cannot be generalized at any spatial location, and we emphasize the importance of assessments tailored to local conditions. Within the growing bioeconomy, residual agricultural biomass presents an attractive feedstock option, though crop residue removal may be detrimental to soil quality by reducing organic carbon. Simulations of soil organic carbon in Swedish arable land indicate that intermediate crops and digestate applications can offset some carbon losses, with intermediate crops increasing soil carbon stocks at equilibrium by about 3% and digestate by around 5%, though results vary spatially. Despite these benefits, residue removal's negative effects are not fully mitigated across all locations, highlighting the need for location‐specific assessments to balance biomass utilization with soil conservation.

Current EU policy calls for decreased emissions of greenhouse gases (GHG) by i.e., replacing fossil fuel in the transportation sector with sustainable biofuels. To avoid indirect land use change (iLUC), the EU at the same time strives to limit the use of crops and to increase the use of residues. In this study we compare climate impact and production cost for biogas and ethanol based on wheat grain and straw, respectively, in a Swedish context. The economic competitiveness for ethanol from straw vs. grain is evaluated based on the mandatory emission reduction for fossil vehicle fuels implemented since July 2018 in Sweden. The result of this study clearly shows that biogas and ethanol from straw have the lowest GHG emissions regardless of the calculation method used, although biofuels from grain also fulfill EU GHG reduction criteria even when suggested iLUC factors are included. It was also shown that the cost of producing straw-based biofuels was higher, thus there is a trade-off between climate impact and costs. The GHG reduction mandate adopted in Sweden partly compensates for this, but is not enough to make ethanol from straw competitive from an economic perspective.

The production of biogas from six agricultural crops was analysed regarding energy efficiency and greenhouse gas (GHG) performance for vehicle fuel from a field-to-tank perspective, with focus on critical parameters and on calculation methods. The energy efficiency varied from 35% to 44%, expressed as primary energy input per energy unit vehicle gas produced. The GHG reduction varied from 70% to 120%, compared with fossil liquid fuels, when the GHG credit of the digestate produced was included through system expansion according to the calculation methodology in the ISO 14044 standard of life cycle assessment. Ley crop-based biogas systems led to the highest GHG reduction, due to the significant soil carbon accumulation, followed by maize, wheat, hemp, triticale and sugar beet. Critical parameters are biogenic nitrous oxide emissions from crop cultivation, for which specific emission factors for digestate are missing today, and methane leakage from biogas production. The GHG benefits were reduced and the interrelation between the crops changed, when the GHG calculations were instead based on the methodology stated in the EU Renewable Energy Directive, where crop contribution to soil carbon accumulation is disregarded. All systems could still reach a 60% GHG reduction, due to the improved agricultural management when digestate replaces mineral fertilisers.

Superabsorbent polymers (SAP) are a central component of hygiene and medical products requiring high liquid swelling, but these SAP are commonly derived from petroleum resources. Here, we show that sustainable and biodegradable SAP can be produced by acylation of the agricultural potato protein side-stream (PPC) with a non-toxic dianhydride (EDTAD). Treatment of the PPC yields a material with a water swelling capacity of ca. 2400%, which is ten times greater than the untreated PPC. Acylation was also performed on waste potato fruit juice (PFJ), i.e. before the industrial treatment to precipitate the PPC. The use of PFJ for the acylation implies a saving of 320 000 tons as CO 2 in greenhouse gas emissions per year by avoiding the industrial drying of the PFJ to obtain the PPC. The acylated PPC shows biodegradation and resistance to mould growth. The possibilities to produce a biodegradable SAP from the PPC allows for future fabrication of environment-friendly and disposable daily-care products, e.g. diapers and sanitary pads. Superabsorbent materials can absorb many times their weight in water, but are commonly derived from petroleum. Here, acylation of coagulated potato protein concentrate or soluble potato protein fruit juice yields an effective, mould-resistant, and biodegradable superabsorbent polymer.

Crop yield has been a major target of plant breeding, although resistance and quality have also been important. The current climate change is calling for breeding actions to mitigate greenhouse gas (GHG) emissions. The present review focuses on opportunities from plant breeding to mitigate climate change while simultaneously securing yield and food requirements, as exemplified by winter wheat cultivation in Northern Europe. Therefore, we review the history of traditional plant breeding, the impact of climate change on crops and implications for plant breeding, opportunities to use plant breeding as a tool to mitigate climate change, and then we assess the estimated mitigation effects from plant breeding and discuss their impact on climate effects. Nitrogen uptake efficiency (NUpE) was indicated as the character with the highest potential to contribute to climate change mitigation, with positive effects also from increased straw length and stubble heights, while increased total biomass yield (root or above-ground) showed less effect. In addition to contributing to climate change mitigation, NUpE might increase profitability for growers and decrease nitrogen leakage from agricultural fields. An increase in NUpE by 15% through plant breeding has the potential to result in reduced GHG emissions corresponding to 30% of the fossil fuel use in agriculture in Sweden.

Sustainability goals regarding biobased chemicals and fuels can lead to increased demand for cereal straw, which could lead to undesirable effects on soil organic matter (SOM) content. The aim of this study was to evaluate the effects of removing straw on SOM, using a life cycle approach based on agricultural statistics and soil carbon modelling. This regional evaluation in southern Sweden showed that the general restrictions on straw removal recommended in many European studies, with demands on the incorporation of at least half of the aboveground straw, is not an efficient means of SOM preservation. Unrestricted straw removal in combination with the cultivation of intermediate crops leads to a much higher SOM build-up. Such measures will increase the availability of removable straw 2.5 times, at little extra cost. The findings of this study demonstrate the necessity of regional evaluation, taking new findings on the impact of straw incorporation on SOM into consideration. This is important for both regional emerging biobased industries, where unnecessary restrictions on straw removal might hamper the development of new production pathways, and for future sustainability in agriculture, where well-intended but inefficient SOM preservation strategies might hinder the implementation of more efficient measures. Graphic Abstract

Improper disposal of organic waste leads to greenhouse gases, pollution, and health risks. Anaerobic digestion offers a sustainable solution by converting this waste into biogas and digestates, which contain valuable nutrients and stimulatory organic compounds that can be recycled to improve plant growth and support food production. Here we review the transformation of liquid and solid digestates into biostimulants by microalgal cultivation, vermicomposting, and insect-based bioconversion. These processes yield phytohormones, polysaccharides, betaines, humic substances, chitin, protein hydrolysates, and growth-promoting microbes, that enhance plant growth and resilience against environmental stresses. Due to the variability in digestate composition, we emphasize the need for optimized formulations, a deep understanding of synergistic interactions among bioactive compounds, and standardized extraction techniques to support broader applications.

Ensuring sustainable management and an adequate supply of freshwater resources is a growing challenge around the world. Even in historically water abundant regions climate change together with population growth and economic development are processes that are expected to contribute to an increase in permanent and seasonal water scarcity in the coming decades. Previous studies have shown how policies to address water scarcity often fail to deliver lasting improvements because they do not account for how these processes influence, and are influenced by, human-water interactions shaping water supply and demand. Despite significant progress in recent years, place-specific understanding of the mechanisms behind human-water feedbacks remain limited, particularly in historically water abundant regions. To this end, we here present a Swedish case study where we, by use of a qualitative system dynamics approach, explore how human-water interactions have contributed to seasonal water scarcity at the local-to-regional scale. Our results suggest that the current approach to address water scarcity by inter-basin water transports contributes to increasing demand by creating a gap between the perceived and actual state of water resources among consumers. This has resulted in escalating water use and put the region in a state of systemic lock-in where demand-regulating policies are mitigated by increases in water use enabled by water transports. We discuss a combination of information and economic policy instruments to combat water scarcity, and we propose the use of quantitative simulation methods to further assess these strategies in future studies.

Grass ley and whole-crop cereals used for biogas production are often finely chopped for subsequent ensiling and anaerobic digestion. Chopping can impact not only ensiling stability, digestibility and risk of process hick-ups in the digester but also harvesting capacity and fuel consumption. Based on field experiment data, the aim of this study was to investigate how three different nominal cutting lengths in the range of 3.5 mm to 12.5 mm impact methane yield and economic viability of grass ley and whole-crop cereals used as biogas substrate. A shorter cutting length affected the specific methane potential differently for the different crops, + 14 to − 25%. In biogas vehicle fuel production, balancing the additional energy and economic costs for shorter cutting length required an increased methane potential of less than 1% and 3%, respectively. As long as a decrease in cutting length increased the methane potential, the energy balance and economic result improved, despite higher energy inputs. However, mechanisms behind the impact on methane potential deserve further attention. In conclusion, we have shown that it is economically viable to produce methane gas, as a vehicle fuel, from several agricultural crops grown in the south of Sweden, i.e. grass ley and whole-crop rye and wheat, when they are harvested/chopped with a forager, ensiled as biogas feedstocks and processed to methane gas in a large-scale biogas plant.

Multifunctional agriculture provides noncommodity functions and services along with food, feed and bioenergy feedstocks, for example by preserving or promoting biodiversity, improving soil fertility, mitigating climate change and environmental degradation, and contributing to the socio‐economic viability of rural areas. Producing biomass for bioenergy from low‐input perennial species mixtures on marginal land has the potential to support biodiversity and soil carbon sequestration in synergy with greenhouse gas mitigation. We compared biomass production in species‐rich mixtures of perennial grasses, legumes and forbs with pure‐stand grasses and relatively species‐poor mixtures under different nitrogen fertilization regimes. Field experiments were performed on different types of marginal land, that is agricultural field margins and land with poor soil fertility, at four sites in southernmost and western Sweden. Biomass production was measured for three years in perennial grasses grown as pure stands, in legume‐grass mixtures, and legume‐grass‐forb mixtures across a species richness gradient. In unfertilized species‐rich mixtures, average biomass yields per experimental site and year were in the range from 3 to 9 metric ton DM ha−1 yr−1. While the most productive pure‐stand grasses fertilized with 60–120 kg N ha−1 yr−1 often produced higher biomass yields than unfertilized mixtures, these differences were generally smaller than the variations between years and sites. Calculations of climate impact using the harvested biomass for conversion to biogas as vehicle fuel showed that the average greenhouse gas emissions per energy unit were about 50% lower in unfertilized systems than in treatments fertilized with 100–120 kg N ha−1 yr−1. Our findings thereby show that unfertilized species‐rich perennial plant mixtures on marginal land provide resource‐efficient biomass production and contribute to the mitigation of climate change. Perennial species mixtures managed with low inputs thus promote synergies between productivity and biodiversity in the perspective of climate‐smart and multifunctional biomass production.