Aims
Predictions of medium to long-term changes in soil organic carbon (SOC) stocks involve simulation models with plant carbon (C) inputs estimated from crop yields using crop harvest indices and ...allometric scaling involving fixed root-to-shoot ratios. The choice of allometric approach and initial distribution of SOC among model pools is crucial for model estimates.
Methods
We evaluated the impact of a modified allometric approach for grass leys and initial model set-up using the C-TOOL model. Four European agricultural long-term experiments were considered including three experiments with different frequency of grass leys in the crop rotation and one permanent grassland.
Results
The modified allometric function for ley relied on fixed below-ground C input regardless of mineral fertilizer inputs and modified pool initialization involved available site history. Including available, but insufficient, pre-experiment history to adjust the initial set-up of model SOC pools did not improve to the C-TOOL simulations. Changing the allometric approach for ley from fixed shoot-to-root ratios to fixed below-ground C input decreased the soil C input dramatically and improved the C-TOOL simulation of SOC stocks for fertilized treatments in all experiments when combined with standard model set-up. For unfertilized treatments, however, the efficiency of the standard allometric function was superior to the modified one.
Conclusions
Our results challenge the prevalent use of allometric approaches based on fixed root-to-shoot in SOC simulation models. The potential of modifying the initial distribution of SOC among model pools by accounting for historic land use remains in the dark.
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BFBNIB, DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NMLJ, NUK, OBVAL, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Plant species diversity may benefit natural grassland productivity, but its effect in managed grassland systems is not well understood. A four-year multispecies grassland experiment was conducted to ...investigate the effect of species diversity-legumes and non-leguminous forbs-on productivity, persistence and sward quality under cutting or grazing regimes and with or without slurry application. Three mixtures were established- 3-mix: grass, red and white clover, 10-mix: 3-mix plus birdsfoot trefoil and six non-leguminous forbs, and 12-mix: 10-mix plus lucerne and festulolium. Species diversity increased sward production and yield persistence under cutting regime. The 12-mix had the highest yield from the second year onwards and no statistically significant yield reduction over four years, while annual yields in the 3-mix and 10-mix decreased significantly with increasing grassland age. The higher yield in the 12-mix was mainly due to the inclusion of high-yielding lucerne. The 10-mix and 12-mix had lower proportions of unsown species than the 3-mix, the difference being dependent on grassland age. Generally, the 3-mix had higher concentrations of in-vitro organic matter digestibility (IVOMD), neutral detergent fiber (NDF) and crude protein (CP), and a lower concentration of ash than the 10-mix and 12-mix. Slurry application increased annual yield production by 10% and changed the botanical composition, increasing the proportion of grass and decreasing the proportion of legumes. Compared to cutting, grazing increased forage production by 9% per cut on average and lowered legume and forb proportions in the mixtures, but yields did not differ among the three mixtures. Overall, our results suggest that species diversity increases sward productivity and persistence only under an ungrazed cutting regime. We conclude that increasing species diversity by selecting appropriate species with compatible management is key to achieving both high yields and high persistence in managed grasslands.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The study investigated the effect of co-ensiling of cover crops (CC) and barley straw (BS) on biogas production. Blends containing chopped CC and BS (mix ratios of 1:0, 2:1, 3:1, 6:1; 10:1 and 19:1 ...(w:w)) were prepared and stored for 4 months prior to the biogas batch assay. Results show that CC is feasible for producing biogas with reasonable CH4 yield (330 mL CH4 gVS−1) and has good storability. Using of co-ensiling blends showed advantages over CC as it elevated the hydrolysis rate (k) from 0.024 to 0.061 d−1 and decreased the lag phase (from 5 to 0.8 days) during the thermophilic (51 °C) batch test. Synergistic effects were observed from both CH4 yield and hemi-cellulose removal. The finding provided an alternative strategy for integrated straw management and CC utilization for improved biogas production.
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•Effects of co-ensiling blends and impact of synergy were investigated.•Cover crop is feasible for biogas and has good storability.•Anaerobic digestion of co-ensiled blend has high hydrolysis rate and low lag phase.•Synergy were observed on CH4 yield and hemicellulose removal of co-ensiled blend.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Many aspects of the feeding ecology of terrestrial oligochaetes are poorly understood despite the essential role of these soil and detritus feeders for maintaining soil fertility. To investigate ...dietary contributions of various soil components to two ecological groups of worms, anecic and endogeic species, we employed δ13C fingerprinting of essential amino acids (EAA) for distinguishing between bacterial, fungal, and plant derived food sources. We collected earthworms and enchytraeids from organic grasslands with grass, clover, and mixtures of these two plants. Our results showed that the worms either relied on plants or bacteria as their primary EAA source, but not on fungi, and that EAA targets were unaffected by crop type. Two anecic species received 60–75% of their EAA from plant sources with bacterial contributions ranging from 18 to 23%. In contrast, both enchytraeids and an endogeic worms relied equally on bacterial and plant derived EAA. Our study provides answers to some of the long-standing questions in regards to the role of bacteria for earthworm nutrition. While bacterial EAA contribution to anecic worms was relatively modest, less than one-quarter, bacterial contribution to endogeic and enchytraeid worms was substantial comprising almost half of their EAA. Our findings are important for understanding how different ecological groups of terrestrial oligochaetes meet nutritional needs and partition food resources.
•Protein sources of worms were identified with amino acid 13C fingerprinting.•Anecic earthworm species relied mostly on plant-derived amino acids.•Endogeic earthworms relied equally on bacterial and plant-derived amino acids.•Enchytraeid worms resemble endogeic earthworms in terms of EAA sources.•EAA targets were neither tied to crop type nor the size of individual earthworms.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
•A sandy loam soil was exposed to DMPP at normal and ten-fold higher dose.•Non-target soil functions and total microbial biomass were unaffected by DMPP.•Minor trends in phospholipid fatty acid ...composition were not significant.•The inhibition of potential ammonia oxidation was independent of DMPP dose.•DMPP reduced cell-specific nitrification rates, but probably not populations.
The nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP) is widely used within agriculture to reduce nitrate leaching and improve nitrogen use efficiency of fertilizers, but few studies examined effects on non-target soil functions and microorganisms, i.e. other than the intended delay of ammonia oxidation. We investigated effects of DMPP amendment equivalent to 0 (Control), 1 (regular dose, RD) or 10 (high dose, HD) kgha−1 in a sandy loam grassland soil at 50% water-filled pore space. Following incubation for 1, 7 or 14 d, soil was analyzed for fluorescein diacetate hydrolysis, dehydrogenase activity, phospholipid fatty acid composition and potential ammonia oxidation. DMPP showed no significant non-target effects (p>0.05), but a possible stress response in HD was indicated by a factor analysis of phospholipid fatty acid composition. There was a strong DMPP inhibition on potential ammonia oxidation which was still significant (p<0.05) in HD after 14 d. In separate treatments receiving 50mg NH4+-Nkg−1 dry soil in addition to DMPP, the inhibition of nitrate accumulation was similar in RD and HD at around 75%. Abundances of the gene amoA from ammonia oxidizing bacteria (AOB) and archaea (AOA) were quantified, and cell-specific nitrification rates were estimated. There was a general trend of increasing AOA and AOB abundance towards the end of incubation irrespective of DMPP treatment, whereas cell-specific activity of AOA and/or AOB was reduced in the presence of DMPP. Overall, this study indicated that DMPP effectively inhibited nitrification activity without effects on ammonia oxidizer populations, as well as non-target soil microorganisms or functions.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Crop mixtures are often beneficial in crop rotations to enhance resource utilization and yield stability. While targeted management, dependent on the local species composition, has the potential to ...increase the crop value, it comes at a higher expense in terms of field surveys. As fine-grained species distribution mapping of within-field variation is typically unfeasible, the potential of targeted management remains an open research area. In this work, we propose a new method for determining the biomass species composition from high resolution color images using a DeepLabv3+ based convolutional neural network. Data collection has been performed at four separate experimental plot trial sites over three growing seasons. The method is thoroughly evaluated by predicting the biomass composition of different grass clover mixtures using only an image of the canopy. With a relative biomass clover content prediction of R
= 0.91, we present new state-of-the-art results across the largely varying sites. Combining the algorithm with an all terrain vehicle (ATV)-mounted image acquisition system, we demonstrate a feasible method for robust coverage and species distribution mapping of 225 ha of mixed crops at a median capacity of 17 ha per hour at 173 images per hectare.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Grassland cultivation can mobilize large pools of N in the soil, with the potential for N leaching and N
O emissions. Spraying with the nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP) ...before cultivation was simulated by use of soil columns in which the residue distribution corresponded to plowing or rotovation to study the effects of soil-residue contact on N transformations. DMPP was sprayed on aboveground parts of ryegrass and white clover plants before incorporation. During a 42-day incubation, soil mineral N dynamics, potential ammonia oxidation (PAO), denitrifying enzyme activity (DEA), nitrifier and denitrifier populations, and N
O emissions were investigated. The soil NO
pool was enriched with
N to trace sources of N
O. Ammonium was rapidly released from decomposing residues, and PAO was stimulated in soil near residues. DMPP effectively reduced NH
transformation irrespective of residue distribution. Ammonia-oxidizing archaea (AOA) and bacteria (AOB) were both present, but only the AOB amoA transcript abundance correlated with PAO. DMPP inhibited the transcription of AOB amoA genes. Denitrifier genes and transcripts (nirK, nirS, and clades I and II of nosZ) were recovered, and a correlation was found between nirS mRNA and DEA. DMPP showed no adverse effects on the abundance or activity of denitrifiers. The
N enrichment of N
O showed that denitrification was responsible for 80 to 90% of emissions. With support from a control experiment without NO
amendment, it was concluded that DMPP will generally reduce the potential for leaching of residue-derived N, whereas the effect of DMPP on N
O emissions will be significant only when soil NO
availability is limiting.
Residue incorporation following grassland cultivation can lead to mobilization of large pools of N and potentially to significant N losses via leaching and N
O emissions. This study proposed a mitigation strategy of applying 3,4-dimethylpyrazole phosphate (DMPP) prior to grassland cultivation and investigated its efficacy in a laboratory incubation study. DMPP inhibited the growth and activity of ammonia-oxidizing bacteria but had no adverse effects on ammonia-oxidizing archaea and denitrifiers. DMPP can effectively reduce the potential for leaching of NO
derived from residue decomposition, while the effect on reducing N
O emissions will be significant only when soil NO
availability is limiting. Our findings provide insight into how DMPP affects soil nitrifier and denitrifier populations and have direct implications for improving N use efficiency and reducing environmental impacts during grassland cultivation.
Intensively managed grasslands are dominated by highly productive grass-clover mixtures. Increasing crop diversity by inclusion of competitive forbs may enhance biomass production and sustainable ...biofuel production. Here we examined if one or all of three forbs (chicory, Cichorium intybus L.; caraway, Carum carvi L.; plantain, Plantago lanceolata L.) included in ryegrass-red clover mixtures enhanced above- and below-ground productivity, and assessed their biofuel potentials, based on a three-year experiment with and without fertilisation as cattle slurry. We determined herbage yield, standing root biomass, and estimated methane energy output and greenhouse gas (GHG) emissions per energy unit using life cycle assessment. Results showed that plantain-containing grass-clover mixtures significantly increased herbage yield, while chicory- or caraway-containing mixtures maintained similar yields to the grass-clover mixture. Standing root biomass of the grass-clover mixture was enhanced by inclusion of caraway and plantain, with that of plantain further enhanced by fertilisation. The highest methane energy output was achieved in plantain-containing grass-clover mixtures. All unfertilised mixtures achieved the 60% reduction in GHG emissions compared to fossil fuel, whereas all fertilised mixtures did not meet the 60% reduction target. These findings suggest that including competitive forbs such as plantain in grass-clover mixtures enhances productivity, supporting low-carbon footprint bioenergy production.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
The aim of the study was epidemiologically to evaluate the long-term effects of opioids on pain relief, quality of life and functional capacity in long-term/chronic non-cancer pain. The study was ...based on data from the 2000 Danish Health and Morbidity Survey. As part of a representative National random sample of 16,684 individuals (>16 years of age), 10,066 took part in an interview and completed a self-administered questionnaire. Cancer patients were excluded. The interview and the self-administered questionnaire included questions on chronic/long-lasting pain (>6 months), health-related quality of life (SF-36), use of the health care system, functional capabilities, satisfaction with medical pain treatment and regular or continuous use of medications. Participants reporting pain were divided into opioid and non-opioid users. The analyses were adjusted for age, gender, concomitant use of anxiolytics and antidepressants and pain intensity. Pain relief, quality of life and functional capacity among opioid users were compared with non-opioid users. Opioid usage was significantly associated with reporting of moderate/severe or very severe pain, poor self-rated health, not being engaged in employment, higher use of the health care system, and a negative influence on quality of life as registered in all items in SF-36. Because of the cross-sectional nature causative relationships cannot be ascertained. However, it is remarkable that opioid treatment of long-term/chronic non-cancer pain does not seem to fulfil any of the key outcome opioid treatment goals: pain relief, improved quality of life and improved functional capacity.
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GEOZS, IJS, IMTLJ, KILJ, OILJ, SBCE, SBJE, UL, UPUK
Anaerobic co-digestion of agricultural by-products or wastes with complementarity characteristics is commonly used to enhance methane yield. This study firstly explores the possibility of ...co-digesting grass and forb species (white clover, chicory and plantain) differing in nutrient composition in enhancing methane yield. This was examined with two inocula (a cattle manure-based inoculum and a grass-based inoculum) in a batch assay. Results showed that co-digesting grass and forbs synergistically enhanced methane yield potential on average by 31 L kg−1 volatile solids (+11%) and reduced lag phase time by 0.8 day in the grass-based inoculum, but not in the cattle manure-based inoculum. Mixtures containing plantain showed more consistent synergistic effect than chicory. Synergistic effects were attributed to more balanced nutrient composition (especially C/N ratio) in grass-forb mixtures. We demonstrate that anaerobic co-digestion of grass and forbs is feasible for enhancing methane yield, which promotes the utilization of multi-species grasslands for bioenergy production.
•Co-digestion of grass and forbs was examined with two inocula in a batch assay.•Co-digestion enhanced bio-methane potential in grass-based inoculum.•Co-digestion reduced the lag phase time in grass-based inoculum.•Synergistic effect was attributed to better nutrient balance in grass-forb mixtures.•No effect of co-digestion occurred in cattle manure-based inoculum.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
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