The Askov long‐term field experiment (1894–2021) represents a unique research platform<sup>#</sup>

Christensen, Bent T.; Thomsen, Ingrid K.; Eriksen, Jørgen

doi:10.1002/jpln.202100354

Cited by 18 publications

(16 citation statements)

References 63 publications

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“…The effect of the management parameters therefore reflects the variation of these parameters on soils at varying initial SOC stocks and paths towards SOC equilibrium, which itself may shift when the management practices are changed (Jensen et al, 2022). Additionally, the effect of management practices before 2009 may still have impacts on the SOC stock dynamics observed between 2009 and 2019, for example, land‐use change (Christensen et al, 2022; Hu et al, 2019).…”

Section: Discussionmentioning

confidence: 99%

“…In addition, the use of cover crops, straw incorporation and application of organic fertilizers may increase SOC stocks (Gross & Glaser, 2021; Jensen et al, 2022; Poeplau & Don, 2015). These effects may be quantified in long‐term field experiments where given management is maintained for several years or decades (Christensen et al, 2022; Hu et al, 2019). However, long‐term experiments testing individual management elements may not reflect agricultural farming practices with frequent changes in cropping sequences and soil management.…”

Section: Introductionmentioning

confidence: 99%

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Limitations of farm management data in analyses of decadal changes in SOC stocks in the Danish soil‐monitoring network

Harbo

Olesen

Lemming

et al. 2023

European J Soil Science

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Changes in soil organic carbon (SOC) storage in agricultural land are an important part of the Land Use, Land‐Use Change and Forestry component of national greenhouse gas emission inventories. Furthermore, as climate mitigation strategies and incentives for carbon farming are being developed, accurate estimates of SOC stocks are essential to verify any management‐induced changes in SOC. Based on agricultural mineral soils in the Danish soil‐monitoring network, we analysed management effects on SOC stocks using data from the two most recent surveys (2009 and 2019). Between 2009 and 2019, the average increase in SOC stock was 1.2 Mg C ha−1 for 0–50 cm despite a loss of 1.2 Mg C ha−1 from the topsoil (0–25 cm), stressing the importance of including deeper soil layers in soil‐monitoring networks. Comparing all four national surveys (1986, 1997, 2009, 2019), the mean SOC stock of mineral soils in Denmark appears stable. The change in SOC stock between 2009 and 2019 was analysed in detail in relation to management practices as reported by farmers. We found that the effects of single management factors were difficult to isolate from co‐varying factors including soil parameters and that the use of farm management data to explain changes in SOC stocks observed in soil‐monitoring networks appears limited. Uncertainty in SOC stock estimates also arises from low sampling frequency and statistical challenges related to regression to the mean. However, repeated stock measurements at decadal intervals still represent a benchmark for the overall development in regional and national SOC storage, as affected by actual farm management.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Limitations of farm management data in analyses of decadal changes in SOC stocks in the Danish soil‐monitoring network

Harbo

Olesen

Lemming

et al. 2023

European J Soil Science

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“…Aarhus University (AU) has a long history of agricultural crop research dating back to former research within the Danish Institute of Agricultural Sciences and Danish Institute of Plant and Soil Science (Christensen et al, 2022). In 2012 an experiment was established at two locations in Denmark to compare very different cropping systems (a range of grassland crops and double cropping systems) with the purpose of investigating potential productivity, whilst also measuring nutrient balances, input demands and greenhouse gas balances.…”

Section: Methodsmentioning

confidence: 99%

Coupling the benefits of grassland crops and green biorefining to produce protein, materials and services for the green transition

Jørgensen

Jensen

Ambye‐Jensen

2022

Grass and Forage Science

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Compared with annual grain and seed crops, perennial grassland has significantly lower losses of nutrients and low pesticide requirements, whilst also supporting soil carbon build‐up. Until now grassland crops have almost exclusively been fed to ruminants and horses. Our experiments on biorefining forages have produced protein of a quality equal to soybean meal. Forage crops can deliver high yields of biomass as well as protein with a well‐balanced amino acid profile. In grass crops from unfertilised permanent grassland, focus has to be on the fibre part of the grass due to a low protein yield. With current techniques we have recovered up to 40% of the forage protein into a protein concentrate with around 50% protein. In addition, a fibre fraction containing 15%–18% protein of dry matter can be produced and used as ruminant feed, bioenergy, or further biorefined into chemical building blocks or bio‐materials. Our feeding experiments have shown that biorefined grassland protein can provide a substitute for soybean meal for poultry and pigs without negative effects on animal performance. The first industrial scale biorefineries on green biomass for feed and bioenergy are now established in Denmark, although more research is needed in order to evaluate protein quality for both feed and food applications. In addition, a full EFSA approval has to be obtained for the application for food. The green biorefinery concept opens new markets for grassland and opportunities for increasing the grassland area to obtain associated ecosystem services.

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“…The soil grows a four-course rotation of winter wheat, silage maize, spring barley, and a grass-clover mixture used for cutting. The addition of lime every 4–5 years keeps soil pH in the range of 5.5–6.5 (Christensen et al, 2019 ). Cologne soil was obtained from the Max Planck Institute for Plant Breeding Research in Cologne, Germany (GPS coordinates: 50.958 N, 6.856 E) and has not been in agricultural use for over 15 years (Bai et al, 2015 ; Harbort et al, 2020 ).…”

Section: Methodsmentioning

confidence: 99%

“…Here, we demonstrate how ecosystem-specific reference databases can be used for exploratory studies to increase the taxonomic resolution in soil microbial profiling studies, leading to new insight. For this, we sequenced 987,353 full-length 16S rRNA genes from two soils commonly used for plant microbiome research: Askov soil, which has been used for plant and soil studies for more than 125 years (Christensen et al, 2019 ), and Cologne soil, which has been used in numerous plant–microbe interaction studies (Bulgarelli et al, 2012 ; Zgadzaj et al, 2016 ; Thiergart et al, 2019 , 2020 ; Wippel et al, 2021 ). The full-length 16S rRNA genes were processed with AutoTax to create a reference database composed of 18,042 ASV-resolved full-length 16S rRNA genes (FL-ASVs) with a complete seven-rank taxonomy (domain to species) for all reference sequences.…”

Section: Introductionmentioning

confidence: 99%

Application of ecosystem-specific reference databases for increased taxonomic resolution in soil microbial profiling

et al. 2022

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Intensive agriculture systems have paved the way for a growing human population. However, the abundant use of mineral fertilizers and pesticides may negatively impact nutrient cycles and biodiversity. One potential alternative is to harness beneficial relationships between plants and plant-associated rhizobacteria to increase nutrient-use efficiency and provide pathogen resistance. Plant-associated microbiota profiling can be achieved using high-throughput 16S rRNA gene amplicon sequencing. However, interrogation of these data is limited by confident taxonomic classifications at high taxonomic resolution (genus- or species level) with the commonly applied universal reference databases. High-throughput full-length 16S rRNA gene sequencing combined with automated taxonomy assignment (AutoTax) can be used to create amplicon sequence variant resolved ecosystems-specific reference databases that are superior to the traditional universal reference databases. This approach was used here to create a custom reference database for bacteria and archaea based on 987,353 full-length 16S rRNA genes from Askov and Cologne soils. We evaluated the performance of the database using short-read amplicon data and found that it resulted in the increased genus- and species-level classification compared to commonly use universal reference databases. The custom database was utilized to evaluate the ecosystem-specific primer bias and taxonomic resolution of amplicon primers targeting the V5–V7 region of the 16S rRNA gene commonly used within the plant microbiome field. Finally, we demonstrate the benefits of custom ecosystem-specific databases through the analysis of V5–V7 amplicon data to identify new plant-associated microbes for two legumes and two cereal species.

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The Askov long‐term field experiment (1894–2021) represents a unique research platform^#

Abstract: The short presentation of site characteristics, experimental layout, historic crop yields and soil C contents included in Sections 2 and 3 draw partly on an institute report presented when the 125 years of experimentation was celebrated in 2019 (see Christensen et al., 2019).

Cited by 18 publications

References 63 publications

Limitations of farm management data in analyses of decadal changes in SOC stocks in the Danish soil‐monitoring network

Limitations of farm management data in analyses of decadal changes in SOC stocks in the Danish soil‐monitoring network

Coupling the benefits of grassland crops and green biorefining to produce protein, materials and services for the green transition

Application of ecosystem-specific reference databases for increased taxonomic resolution in soil microbial profiling

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The Askov long‐term field experiment (1894–2021) represents a unique research platform#

Abstract: The short presentation of site characteristics, experimental layout, historic crop yields and soil C contents included in Sections 2 and 3 draw partly on an institute report presented when the 125 years of experimentation was celebrated in 2019 (see Christensen et al., 2019).

Cited by 18 publications

References 63 publications

Limitations of farm management data in analyses of decadal changes in SOC stocks in the Danish soil‐monitoring network

Limitations of farm management data in analyses of decadal changes in SOC stocks in the Danish soil‐monitoring network

Coupling the benefits of grassland crops and green biorefining to produce protein, materials and services for the green transition

Application of ecosystem-specific reference databases for increased taxonomic resolution in soil microbial profiling

Contact Info

Product

Resources

About

The Askov long‐term field experiment (1894–2021) represents a unique research platform^#