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Straw returning enhances soil fertility and increases corn yield, but the impact on soil fertility varies with different incorporation methods. To explore the optimal straw-returning method, this study, based on a long-term field experiment, investigated the following different corn-straw-returning methods: deep plowing and straw returning (B), rotary tillage and straw returning (RT), crushing and mixing straw returning (TM), pulverized cover straw returning (C), high-stubble-retention straw returning (LHS), strip cover (S), and flat no-tillage without straw returning (CK). High-throughput sequencing technology was employed to analyze the soil bacterial community composition and structural changes under different straw-returning methods. The study further explored the relationships between the soil bacterial community and nutrient content. The results indicated that different straw-returning methods altered the composition and structure of the soil bacterial community. The TM treatment significantly increased the richness and diversity of the soil bacterial communities. Shredding and covering (C and TM) effectively improved the soil nutrient content and bacterial community structure. In the C treatment, the abundance of Blastococcus, Nocardioides, and Microvirga increased the most, by 241.02%, 77.79%, and 355.08%, respectively, compared with CK. In the TM treatment, Pseudarthrobacter showed the highest abundance, increasing by 343.30%. The genes involved in soil carbon hydrolysis (pulA), nitrification (hao), organic nitrogen degradation and synthesis (gudB), and the nitrogen limitation response (glnR) significantly decreased by 56.21%, 78.75%, 66.46%, and 67.40%, respectively, in the C treatment. The genes involved in soil carbon hydrolysis (IMA), carbon fixation (pccB-A), methane metabolism (moxF), nitrate reduction in soil (nirD), organic nitrogen degradation and synthesis (gdh, ureAB, ureE), and phosphate absorption (glpT) significantly increased by 93.37%, 92.68%, 95.00%, 23.42%, 35.40%, 114.21%, 59.14%, and 75.86%, respectively, in the C treatment. The nitrate reduction gene (nrfA) significantly increased by 80.27% in the TM treatment. Therefore, we concluded that straw primarily stimulates the activity of bacterial communities and regulates the bacterial community by changing the relative abundance of the soil microorganisms and functional genes, thereby improving the soil nutrient content. This study considered pulverized cover straw returning and crushing and mixing straw returning to be the most reasonable methods. [ABSTRACT FROM AUTHOR]

Simple Summary: The potato is the most important non-cereal food crop worldwide. Silicon (Si) fertilizers have been reported to improve potato growth and yield. We used results from two field experiments in the temperate zone to gain insight into silica accumulation in potato plants as well as corresponding long-term potato yield performance. We found relatively low Si contents in potato plants grown in soils with different concentrations of plant-available Si (field experiment 1). Moreover, potato yield was not correlated to plant-available Si concentrations in soils in the long term (1965–2015, field experiment 2). Based on our results, we ascribe the reported positive effects of Si fertilization on potatoes rather to effects of the used Si fertilizers than to silica accumulation in potato plants. While Si fertilizers applied directly to the leaves can prevent fungal infections, soil-applied Si fertilizers can enhance phosphorus and water availability in agricultural soils. With our study, we aim to inspire further research on Si fertilization–potato relationships. The corresponding results will help to derive practice-oriented recommendations for potato growers worldwide to cope with the challenges of climate change. The potato is the most important non-cereal food crop, and thus improving potato growth and yield is the focus of agricultural researchers and practitioners worldwide. Several studies reported beneficial effects of silicon (Si) fertilization on potato performance, although plant species from the family Solanaceae are generally considered to be non-Si-accumulating. We used results from two field experiments in the temperate zone to gain insight into silica accumulation in potato plants, as well as corresponding long-term potato yield performance. We found relatively low Si contents in potato leaves and roots (up to 0.08% and 0.3% in the dry mass, respectively) and negligible Si contents in potato tuber skin and tuber flesh for plants grown in soils with different concentrations of plant-available Si (field experiment 1). Moreover, potato yield was not correlated to plant-available Si concentrations in soils in the long term (1965–2015, field experiment 2). Based on our results, we ascribe the beneficial effects of Si fertilization on potato growth and yield performance reported in previous studies mainly to antifungal/osmotic effects of foliar-applied Si fertilizers and to changes in physicochemical soil properties (e.g., enhanced phosphorus availability and water-holding capacity) caused by soil-applied Si fertilizers. [ABSTRACT FROM AUTHOR]

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Organic wastes (OW) are rich in nutrients, and their recycling into agriculture can substitute chemical fertilizers. The level of substitution (partial with mineral fertilizer or exclusive with only OW), along with the method, amount, and timing of OW application, as well as the crop type, can impact crop productivity. The temporal dynamics of crop productivity after repeated applications of OW remain uncertain. Thus, two French long‐term field experiments (QualiAgro and PROspective, started in 1998 and 2000, respectively) were used to evaluate the effect of repeated OW applications on crop yield dynamics and investigate the potential driving factors affecting crop yields. Six different OW were applied: urban sewage sludge (SLU), green waste and SLU compost (GWS), biowaste compost (BIO), municipal solid waste compost (MSW), farmyard manure (FYM), and composted FYM (FYMC). The OW were applied every 2 years in QualiAgro (~4 t C ha−1) and PROspective (~1.7 t C ha−1). QualiAgro was studied under high and low mineral N conditions, while PROspective was examined with and without mineral N fertilization. The results indicated that at the QualiAgro site, a combination of OW and high mineral N treatments resulted in higher maize and wheat yields compared to the mineral N control, while the combination of OW and low mineral N reached the same maize and wheat yield as the mineral N control after 3 and 6 applications of OW, respectively. At the PROspective site, partially substituting mineral fertilizer with OW maintained maize yields but decreased wheat yields, while full substitution led to a decrease in both maize and wheat yields compared to the mineral N control. Results from the gradient boosting model (GBM) showed that soil total N rather than mineral N input was the primary driver of the relative maize yield, while mineral N fertilizer input was more critical for wheat during the second year. We conclude that the joined use of OW and mineral fertilizers is superior to using OW or mineral fertilizer alone for maintaining high yields and soil fertility. We further suggest that OW full substitution of mineral fertilizer may need to apply OW more frequently to meet the crop demands, and/or to use OW with higher N availability like digestates. [ABSTRACT FROM AUTHOR]

The influence of the quantities and ratios of dissolved organic carbon (DOC) and dissolved nitrogen (DN) generated by different chemical quality classes of organic residues on soil microbial processes in the decomposition process is not well understood. If the DOC-to-DN ratio (hereafter, ratio) of the substrate is close to that of the microbial C-to-N ratio, then the DOC-and-DN stoichiometry of the substrate is balanced, resulting in enhanced microbial processing, i.e., carbon use efficiency (CUE). Uncertainty exists about the influence of DN and the DOC-to-DN ratio on CUE, particularly in high-quality class (high nitrogen) residue-treated soils. A long-term field experiment was used to explore the effect of the annual application of residues of different quality classes on decomposition processes, focusing on the effects of DOC, DN, and the ratio on the microbial metabolic quotient (qCO2), which is the inverse of CUE. DOC and DN were extracted from soils during the 13th year of the experiment. Soils treated with high-quality class groundnut residue (high-nitrogen) had higher DN (5.4 ± 2.6 mg N kg−1) and a lower ratio (6.8 ± 2.6) than those treated with medium-quality (medium-nitrogen) tamarind (3.0 ± 0.6 and 10.7 ± 2.2, respectively). The positive influence of DN on qCO2 (R2 = 0.49 *) in groundnut-treated soil suggested that the high bioavailability of DN reduced CUE due to imbalanced DOC-and-DN stoichiometry. This contradicted earlier published findings on high-nitrogen residues which had balanced DOC-and-DN stoichiometry. The positive influence of the ratio on qCO2 under the tamarind-treated soil (R2 = 0.60 *) indicated that its balanced DOC-and-DN stoichiometry enhanced CUE. High-quality class organic residues can result in either higher or lower CUE than their lower-quality class counterparts depending on whether the resulting DOC-and-DN stoichiometry is balanced or imbalanced. [ABSTRACT FROM AUTHOR]

Carbon sequestration in soils under agricultural use can contribute to climate change mitigation. Spatial–temporal soil organic carbon (SOC) monitoring requires more efficient data acquisition. This study aims to evaluate the potential of spectral on-the-go proximal measurements to serve these needs. The study was conducted as a long-term field experiment. SOC values ranged between 14 and 25 g kg−1 due to different fertilization treatments. Partial least squares regression models were built based on the spectral laboratory and field data collected with two spectrometers (site-specific and on-the-go). Correction of the field data based on the laboratory data was done by testing linear transformation, piecewise direct standardization, and external parameter orthogonalization (EPO). Different preprocessing methods were applied to extract the best possible information content from the sensor signal. The models were then thoroughly interpreted concerning spectral wavelength importance using regression coefficients and variable importance in projection scores. The detailed wavelength importance analysis disclosed the challenge of using soil spectroscopy for SOC monitoring. The use of different spectrometers under varying soil conditions revealed shifts in wavelength importance. Still, our findings on the use of on-the-go spectroscopy for spatial–temporal SOC monitoring are promising. [ABSTRACT FROM AUTHOR]

The article considers the results of many years of field experiment (1968-2018) conducted in the Central part of the Non-Chernozem zone of Russia (Vladimir region). The research was carried out during eleven rotations of the four-field grain crop rotation. The study shows the effect of use of organic and mineral fertilizers applied in various doses and combinations on crop rotation yield, fertility of sod-podzolic sandy loam soil. It was found that the organomineral fertilizer system (manure 10 t/ha + N50P25K60) provided stable crop rotation productivity (on average for eleven rotations) at the level of 39.9 c. e./ha, or 79.7 % higher than the control without fertilizers. The mineral fertilizer system at medium doses of fertilizers (N50P25K60) was at the level of the organomineral system. The organic system was inferior in efficiency to the mineral system, both at medium doses (manure 10 t/ha) and at elevated doses (manure 20 t/ha). At the same time, the long-term use of organic fertilizers provided an increase in the humus content, depending on the dose of litter manure, by 16-36 % compared to the initial values. The use of organic fertilizers led to the stabilization of the content of available forms of potassium in the soil at an average and elevated level, respectively. Stabilization of the content of mobile phosphorus in the soil at the level of average supply was noted in mineral, organomineral and organic fertilizer systems, respectively, with low and medium doses. When using increased doses of fertilizers, there is a further increase in the content of nutrients in the soil. Growing crops in crop rotation without the use of organic and mineral fertilizers gradually led to a decrease in yield. The use of fertilizers provided greater stability of crop yields over the years of the study compared to the variant without fertilizers. The soil in the variants with organic (manure 20 t/ha) and organomineral (manure 10 t/ha + N50P25K60) fertilizer systems was characterized by high values of the main physiological groups of microorganisms. The ratio of the number of amylolytic and proteolytic microorganisms was 1.1-1.2, that indicated a balance in the processes of mineralization of organic matter in the soil and its humification.

Straw returning enhances soil fertility and increases corn yield, but the impact on soil fertility varies with different incorporation methods. To explore the optimal straw-returning method, this study, based on a long-term field experiment, investigated the following different corn-straw-returning methods: deep plowing and straw returning (B), rotary tillage and straw returning (RT), crushing and mixing straw returning (TM), pulverized cover straw returning (C), high-stubble-retention straw returning (LHS), strip cover (S), and flat no-tillage without straw returning (CK). High-throughput sequencing technology was employed to analyze the soil bacterial community composition and structural changes under different straw-returning methods. The study further explored the relationships between the soil bacterial community and nutrient content. The results indicated that different straw-returning methods altered the composition and structure of the soil bacterial community. The TM treatment significantly increased the richness and diversity of the soil bacterial communities. Shredding and covering (C and TM) effectively improved the soil nutrient content and bacterial community structure. In the C treatment, the abundance of Blastococcus, Nocardioides, and Microvirga increased the most, by 241.02%, 77.79%, and 355.08%, respectively, compared with CK. In the TM treatment, Pseudarthrobacter showed the highest abundance, increasing by 343.30%. The genes involved in soil carbon hydrolysis (pulA), nitrification (hao), organic nitrogen degradation and synthesis (gudB), and the nitrogen limitation response (glnR) significantly decreased by 56.21%, 78.75%, 66.46%, and 67.40%, respectively, in the C treatment. The genes involved in soil carbon hydrolysis (IMA), carbon fixation (pccB-A), methane metabolism (moxF), nitrate reduction in soil (nirD), organic nitrogen degradation and synthesis (gdh, ureAB, ureE), and phosphate absorption (glpT) significantly increased by 93.37%, 92.68%, 95.00%, 23.42%, 35.40%, 114.21%, 59.14%, and 75.86%, respectively, in the C treatment. The nitrate reduction gene (nrfA) significantly increased by 80.27% in the TM treatment. Therefore, we concluded that straw primarily stimulates the activity of bacterial communities and regulates the bacterial community by changing the relative abundance of the soil microorganisms and functional genes, thereby improving the soil nutrient content. This study considered pulverized cover straw returning and crushing and mixing straw returning to be the most reasonable methods.

Mid-term (MTEs, 5-20 years) and long-term (LTEs, 20+ years) field experiments are key sources of information to design future climate-smart agriculture. Within the European Joint Program SOIL (EJP SOIL), we built the EJP SOIL-MTE/LTE metadataset that contains metadata from 240 MTEs/LTEs across Europe. Metadata collected included precise descriptions of the treatments (combination of factors such as tillage, crop type/rotation, amendments/fertilizers, grazing and pest/weed management), soil and crop measurements and pedo-climatic information. Using different figures and dashboards, an overview of those MTEs/LTEs is presented and specific research themes (tillage systems, residue management, amendment type and cover crops) are further analysed within their pedo-climatic context. An interactive web portal developed in collaboration with the BonaRes project (https://lte.bonares.de), enables users to explore the metadataset and find relevant MTEs/LTEs for specific combinations of practices (e.g. all MTEs/LTEs that investigate cover crops on a Cambisol in no-tillage system). Finally, a SWOT (Strengths, Weaknesses, Opportunities, Threats) analysis of the metadataset was carried out to highlight the potential contribution of MTEs/LTEs to a harmonized European soil observation and monitoring approach. We propose that the metadataset could be elaborated with metadata from other existing MTEs/LTEs in Europe or even worldwide. [ABSTRACT FROM AUTHOR]

Fertilization methods have the capacity to modify both soil fertility and biological characteristics, consequently affecting the ecological functions of the soil. Straws are a hard crop residue to decompose, and stimulate the appearance of a specific functional microbiome. The microbial functional profile is correlated with the application of calcium carbonate (CaCO3) and fertilizers containing nitrogen, phosphorus, potassium (NPK). The present study aims to analyze the effect of long-term application of inorganic fertilizers and liming on the functional soil microbial communities. A modified EcoPlate method was used to incorporates the utilization of straw subjected to a 30-day incubation period in the soil at the Livada Agricultural Research and Development Station. In the aftermath of the Ecoplate experiment, discernible alterations in substrate solubilization rates have been noted across diverse soil compositions, spanning from untreated soil to those enriched with nitrogen, phosphorus, and an NPK complex. The results provide information on important functional soil microbial assemblages influenced by fertilizer application and the detection of the most active functional gropus associated with straw decomposition process. [ABSTRACT FROM AUTHOR]

The pqqC and phoD genes encode pyrroloquinoline quinone synthase and alkaline phosphomonoesterase (ALP), respectively. These genes play a crucial role in regulating the solubilization of inorganic phosphorus (Pi) and the mineralization of organic phosphorus (Po), making them valuable markers for P-mobilizing bacterial. However, there is limited understanding of how the interplay between soil P-mobilizing bacterial communities and abiotic factors influences P transformation and availability in the context of long-term fertilization scenarios. We used real-time polymerase chain reaction and high-throughput sequencing to explore the characteristics of soil P-mobilizing bacterial communities and their relationships with key physicochemical properties and P fractions under long-term fertilization scenarios. In a 38-year fertilization experiment, six fertilization treatments were selected. These treatments were sorted into three groups: the non-P-amended group, including no fertilization and mineral NK fertilizer; the sole mineral-P-amended group, including mineral NP and NPK fertilizer; and the organically amended group, including sole organic fertilizer and organic fertilizer plus mineral NPK fertilizer. The organically amended group significantly increased soil labile P (Ca2-P and enzyme-P) and Olsen-P content and proportion but decreased non-labile P (Ca10-P) proportion compared with the sole mineral-P-amended group, indicating enhanced P availability in the soil. Meanwhile, the organically amended group significantly increased soil ALP activity and pqqC and phoD gene abundances, indicating that organic fertilization promotes the activity and abundance of microorganisms involved in P mobilization processes. Interestingly, the organically amended group dramatically reshaped the community structure of P-mobilizing bacteria and increased the relative abundance of Acidiphilium, Panacagrimonas, Hansschlegelia, and Beijerinckia. These changes had a greater positive impact on ALP activity, labile P, and Olsen-P content compared to the abundance of P-mobilizing genes alone, indicating their importance in driving P mobilization processes. Structural equation modeling indicated that soil organic carbon and Po modulated the relationship between P-mobilizing bacterial communities and labile P and Olsen-P, highlighting the influence of SOC and Po on the functioning of P-mobilizing bacteria and their impact on P availability. Overall, our study demonstrates that organic fertilization has the potential to reshape the structure of P-mobilizing bacterial communities, leading to increased P mobilization and availability in the soil. These findings contribute to our understanding of the mechanisms underlying P cycling in agricultural systems and provide valuable insights for enhancing microbial P mobilization through organic fertilization. [ABSTRACT FROM AUTHOR]

Straw return can improve rice eating quality by modifying starch formation from long-term field trials, whereas the relevant mechanisms are still unknown. A long-term field experiment, including straw removal (CK), straw burning return (SBR), and straw return (SR) was conducted to investigate the starch structure, physicochemical properties, and cooked rice textures of indica early- and late-rice. Compared with CK, SBR and SR enhanced relative crystallinity, amylopectin long chains in both rice seasons, and gelatinization temperatures in late rice. Compared to SBR, SR decreased protein content and amylopectin short chains but increased starch branching degree, breakdown, and stickiness, ultimately contributing to improved starch thermal and pasting properties. Meanwhile, SR decreased hardness, cohesiveness, and chewiness, resulting in cooked texture meliorated, which was mainly attributed to amylopectin chain length and starch granule size. The results suggest that SR increased cooked texture of indica rice by altering starch structural and physicochemical properties.

Biological nitrogen fixation (BNF) is important to sustain nitrogen fertility of paddy soil and rice yield, while could be affected by nitrogen fertilization. Iron-reducing bacteria, Anaeromyxobacter and Geobacter, are newly found diazotrophic bacteria predominant in paddy soil. Experimental field of this study is a long-term (35 years) nitrogen fertilized (6.0 g N/m2/year) and unfertilized paddy field, where ca. 70% of rice yield was obtained yearly in nitrogen unfertilized plot (443 ± 37 g/m2) compared to fertilized plot (642 ± 64 g/m2). Effects of long-term nitrogen fertilization/unfertilization on soil properties related to BNF were investigated with special reference to diazotrophic iron-reducing bacteria. Soil chemical/biochemical properties, soil nitrogen-fixing activity, and community composition of diazotrophic bacteria were similar between nitrogen fertilized and unfertilized plot soils. In both plot soils, Anaeromyxobacter and Geobacter were the most predominant diazotrophs. Their nifD transcripts were detected at similar level, while those of other general diazotrophs were under detection limit. It was concluded that long-term use/unuse of nitrogen fertilizer in this field did not affect the predominance and nitrogen-fixing activity of diazotrophic iron-reducing bacteria, composition of other general diazotrophs, and the resulting soil nitrogen-fixing activity. BNF, primarily driven by diazotrophic iron-reducing bacteria, might significantly contribute to sustain soil nitrogen fertility and rice yield in both plot soils. Appropriate soil management to maintain BNF, including diazotrophic iron-reducing bacteria, will be important for sustainable soil nitrogen fertility and rice production. [ABSTRACT FROM AUTHOR]

The influence of the quantities and ratios of dissolved organic carbon (DOC) and dissolved nitrogen (DN) generated by different chemical quality classes of organic residues on soil microbial processes in the decomposition process is not well understood. If the DOC-to-DN ratio (hereafter, ratio) of the substrate is close to that of the microbial C-to-N ratio, then the DOC-and-DN stoichiometry of the substrate is balanced, resulting in enhanced microbial processing, i.e., carbon use efficiency (CUE). Uncertainty exists about the influence of DN and the DOC-to-DN ratio on CUE, particularly in high-quality class (high nitrogen) residue-treated soils. A long-term field experiment was used to explore the effect of the annual application of residues of different quality classes on decomposition processes, focusing on the effects of DOC, DN, and the ratio on the microbial metabolic quotient (qCO2), which is the inverse of CUE. DOC and DN were extracted from soils during the 13th year of the experiment. Soils treated with high-quality class groundnut residue (high-nitrogen) had higher DN (5.4 ± 2.6 mg N kg−1) and a lower ratio (6.8 ± 2.6) than those treated with medium-quality (medium-nitrogen) tamarind (3.0 ± 0.6 and 10.7 ± 2.2, respectively). The positive influence of DN on qCO2 (R2 = 0.49 *) in groundnut-treated soil suggested that the high bioavailability of DN reduced CUE due to imbalanced DOC-and-DN stoichiometry. This contradicted earlier published findings on high-nitrogen residues which had balanced DOC-and-DN stoichiometry. The positive influence of the ratio on qCO2 under the tamarind-treated soil (R2 = 0.60 *) indicated that its balanced DOC-and-DN stoichiometry enhanced CUE. High-quality class organic residues can result in either higher or lower CUE than their lower-quality class counterparts depending on whether the resulting DOC-and-DN stoichiometry is balanced or imbalanced.

Intensive agriculture has increased global food production, but also impaired ecosystem services and soil biodiversity. Organic fertilization, essential to organic and integrated farming, can provide numerous benefits for soil quality but also compromise the environment by polluting soils and producing greenhouse gases through animal husbandry. The need for reduced stocking density is inevitably accompanied by lower FYM inputs, but little research is available on the impact of these effects on the soil microbiome. We collected soil samples from winter wheat plots of a 42-year-old long-term trial comparing different farming systems receiving farmyard manure at two intensities and measured soil quality parameters and microbial community diversity through DNA metabarcoding. High-input fertilization, corresponding to 1.4 livestock units (LU) improved the soil's nutritional status and increased soil microbial biomass and respiration when compared to low-input at 0.7 LU. Bacterial and fungal α-diversity was largely unaffected by fertilization intensity, whereas their community structure changed consistently, accompanied by an increase in the bacterial copiotroph-to-oligotroph ratio in high-input systems and by more copiotrophic indicator OTUs associated with high than low-input. This study shows that reduced nutrient availability under low-input selects oligotrophic microbes efficiently obtaining nutrients from various carbon sources; a potentially beneficial trait considering future agroecosystems. [ABSTRACT FROM AUTHOR]

Carbon sequestration in soils under agricultural use can contribute to climate change mitigation. Spatial–temporal soil organic carbon (SOC) monitoring requires more efficient data acquisition. This study aims to evaluate the potential of spectral on-the-go proximal measurements to serve these needs. The study was conducted as a long-term field experiment. SOC values ranged between 14 and 25 g kg−1 due to different fertilization treatments. Partial least squares regression models were built based on the spectral laboratory and field data collected with two spectrometers (site-specific and on-the-go). Correction of the field data based on the laboratory data was done by testing linear transformation, piecewise direct standardization, and external parameter orthogonalization (EPO). Different preprocessing methods were applied to extract the best possible information content from the sensor signal. The models were then thoroughly interpreted concerning spectral wavelength importance using regression coefficients and variable importance in projection scores. The detailed wavelength importance analysis disclosed the challenge of using soil spectroscopy for SOC monitoring. The use of different spectrometers under varying soil conditions revealed shifts in wavelength importance. Still, our findings on the use of on-the-go spectroscopy for spatial–temporal SOC monitoring are promising.

The fertilization with organic amendments and digestates from biogas plants is increasingly used to increase carbon stock and to improve the soil quality, but little is still known about their long‐term effects. A common method to analyse organic amendments and their mineralization is incubation experiments, where amendments get incubated with soil while CO2 release is measured over time. In a previous study, carbon models have been applied to model the carbon dynamics of incubation experiments. The derived parameters describing the carbon turnover of the CCB model (CANDY Carbon Balance) are used to simulate the SOC and SON dynamics of a long‐term field trial. The trial was conducted in Berge (Germany) where organic amendments like slurry, farmyard manure or digestates were systematically applied. To grant a higher model flexibility, the amounts of crop residues were calculated for roots and stubble separately. Furthermore, the mineralization dynamics of roots and stubble are considered by the model parameters for each crop. The model performance is compared when using the dry matter and carbon content received from the field trial and the incubation experiments, to evaluate the transferability. The results show that the incubation parameters are transferable to the field site, with rRMSE < 10% for the modelled SOC and rRMSE between 10% and 15% for the SON dynamics. This approach can help to analyse long‐term effects of unexplored and unusual organic fertilizers under field conditions, whereat the model is used to upscale the C dynamics from incubation experiments, considering environmental conditions. [ABSTRACT FROM AUTHOR]

Climate change will strongly influence agricultural practices in the future. In order to promote resource-efficient agriculture, it is important to analyse the impact of climate variation on crop yields. In this study, we report yields of spring wheat, winter barley, maize, potato and sugar beet from the long-term crop rotation and fertilization experiment Demo in Switzerland and analyze their response to different climate variables (e.g., annual and seasonal temperature, precipitation, evapotranspiration, number of heat days and days of heavy rainfall). In addition, we investigate the impact of readily plant-available soil potassium (K) on the relationship of crop yields and precipitation. Annual and summer temperatures increased by 1 °C and 1.5 °C, respectively, over the observation period, and both the number of heat days and days of heavy rainfall increased in summer. Rising summer temperatures have a negative impact on all crop yields, which was most prominent for spring wheat, potato and maize. Annual, spring and summer precipitation show varying effects on different crops. For maize, soil K has a mediating effect on yield reductions under low spring precipitation. Yields are significantly reduced by 1 t ha−1 per 100 mm reduction of precipitation below a soil K threshold of 7 mg K kg−1 soil. Based on these results and the future climate scenarios for Switzerland, crop rotations with less heat-sensitive species and early-maturing varieties should be considered. In order to keep future irrigation demands and costs as low as possible, the soil K fertility classes in the Swiss K fertilization guidelines might need to be revisited. Our study is one of a few long-term observations that show the impact of climate variation on crop yields and highlights the potential of K management as a climate change adaptation measure. • Yield response of wheat, barley, maize, potato and sugar beet to climate variables. • Rising summer temperatures negatively affect all crop yields. • Soil potassium mediates yield reductions in maize under low spring precipitation. • Soil potassium fertility classes in fertilization guidelines might need revisions. [ABSTRACT FROM AUTHOR]

Mixed systems of grain and livestock production based on pasture-crop rotations are a promising strategy to promote agriculture resilience and allow an ecological intensification of agriculture yet little is known about underlying processes in soil. To test the hypothesis that pasture-crop rotations preserve soil structure and select for beneficial soil and rhizosphere microbiota, supporting soil health and grain production, a long-term field experiment under no-tillage was studied. The experiment evaluated a gradient of land use intensities and vegetation diversities, from highly intensive continuous cropping to the least intensive system i.e. a nearby natural grassland, with two intermediate land use intensities i.e. short pasture-crop rotation and long pasture-crop rotation. Soil health was assessed based on soil physicochemical properties, microbial (Bacteria/Archaea and Fungi) community diversity and composition and oat performance. Pasture-crop rotations preserved soil bulk density and larger aggregates better than continuous cropping. High-throughput amplicon sequencing of 16S rRNA gene and ITS fragments revealed that the pasture-crop rotations fostered taxa that are associated with soil structure maintenance and selected potential plant-beneficial bacterial genera in the oat rhizosphere (i.e. Bosea , Devosia and Microbacterium), that may have contributed to the observed increase in N uptake, N accumulation and biomass in oat. In summary, this study shows that pasture-crop rotations are an ecologically sustainable alternative to continuous cropping in the Uruguayan Pampa biome. [Display omitted] • Pasture-crop rotations preserved soil structure and yielded higher oat biomass. • Land use intensity affected soil and rhizosphere microbial communities. • Pasture-crop rotations enriched Devosia , Microbacterium , Bosea, Nitrososphaeraceae. • Duration and vegetation of pasture determined the extent of its soil legacy. • Pasture-crop rotations are a sustainable alternative to continuous cropping. [ABSTRACT FROM AUTHOR]

Tropical soils play a critical role in the global biogeochemical cycles and are essential for maintaining the Earth's carbon balance. Understanding the dynamics of dissolved organic matter (DOM) is paramount due to its implications for ecosystem functioning and nutrient cycling. This study comprehensively evaluated the origin, distribution, and composition of DOM and inorganic solutes in Brazilian tropical agricultural soils. Multiple analytical techniques were utilized to assess DOM from soil profiles (0–100 cm depth) across a spectrum of land uses, including a native Atlantic Forest, a degraded pasture, as well as intensive grazing, extensive grazing, and silvopastoral systems. Inorganic elements were quantified to assess the coupling between the organic and inorganic biogeochemical cycles. The dominance of C 4 carbon in topsoil layers suggested substantial contributions of organic matter from grasses to the soil organic matter pool. However, with increased depth, C 3 carbon inputs became more prominent, indicating the influence of forest vegetation that existed prior to the implementation of agricultural managements. DOM concentrations decreased with soil depth due to reduced carbon inputs, sorption to minerals, or oxidation. DOM composition did not show significant changes among different land use and managements. Lignin was identified as the primary contributor to oxidized DOM with increasing soil depth. The composition of DOM exhibited a shift from more aromatic and higher molecular weight compounds in topsoil layers to smaller, more aliphatic compounds in subsoil layers. Our key findings revealed that aliphatic compounds, particularly fatty acids, tend to accumulate in deeper soil layers. This phenomenon was consistent in pastures dominated by grasses but not in soils near treed vegetation. Overseeding (from C 3 plants) did not significantly impact DOM compositions, emphasizing the persistence of C 4 plants in these systems. The presence of inorganic elements in soil water extracts showed minimal impact on DOM dynamics, suggesting decoupled organic and inorganic biogeochemical cycles in tropical pasturelands. [Display omitted] • DOM in topsoil layers showed high C 4 contributions, while subsoil layers showed higher C 3 inputs. • Aromatic compounds became oxidized with increasing soil depth. • Fatty acids were produced by lignin oxidation or selectively preserved in subsoil layers. • Inorganic solutes might not play a major role in soil biogeochemistry. [ABSTRACT FROM AUTHOR]

Composition and availability of soil organic nitrogen play a key role in soil N retention and supply. The application of traditional chemical fertilizers can improve soil production and crop yields. However, it also leads to low N utilization efficiency and soil solidification. Previous studies have shown that fertilizers added with biochar can improve soil fertility and facilitate soil nutrient transformation by regulating soil biological indicators. However, whether biochar used with fertilizers can promote nutrient cycling in the long term, which remains to be tested. Therefore, this study aims to explore the long-term effects of biochar with different levels used with fertilizers on soil fertility, N supply potential of organic N, and microbial communities, thus, providing a theoretical reference for the rational management of biochar applications. In this study, a field experiment was carried out from 2013 to 2018 assess dynamic changes in organic N fractions and diversity and richness of microbial communities under the impacts of chemical fertilizers combined with different levels of biochar. Biochar with no amendment (CK), biochar with 15.75 t ha−1 (BC1), biochar with 31.5 t ha−1 (BC2), and biochar with 47.25 t ha−1 (BC3) are four biochar levels that were tested in this study. The results show that compared with CK, those other three biochar levels can increase soil organic matter, C/N, and pH values. Acid-hydrolysable N (AHN) makes a major contribution to organic N in soil. Biochar retention for six years has significantly affected AHN levels, as well as its four fractions, namely, amino acid N (AAN), acid-hydrolysable ammonium N (AN), amino sugar N (ASN), and hydrolysable unknown N (HUN). Some vital biological characteristics, with which each AHN fraction is primarily regulated, can be altered with the application of biochar. That is, AAN is mainly controlled by enriched Verrucomicrobia , Cyanobacteria , Glucosylbacteria , and Nitrospira , and reduced soil urease, while AN is mainly controlled by enriched Verrucomicrobia , Bacteroidetes , Gemmatimonadetes , Acidobacteria , and Proteobacteria. ASN is regulated by enriched Acidobacteria and depleted soil protease, while HUN is regulated by Gemmatimonadetes and enriched soil nitrate reductase. It has been found that microbial and soil enzyme activities are involved in N cycle processes, indicating that the formation of AHN fractions is closely associated with biochar-induced specific microbial and enzyme activities. This study has provided new insights into the influences of biochar with different levels on distribution of soil organic N fractions, and shifts in soil enzyme activities and microbial communities. • Soil organic matter, C/N and pH increased during six-year of biochar retention. • Soil nitrate reductase activities increased under amounts of biochar retention. • Soil urease activities decreased under amounts of biochar retention. • Soil organic nitrogen fractions positively with soil microbial community. [ABSTRACT FROM AUTHOR]

Maintaining the optimal soil quality stands a fundamental determinant for sustained yield of rice-wheat system (RWS) in Indo Gangetic plains (IGP) of India. To uphold soil quality, implementing minimum/no tillage along with addition of crop residue are required. To evaluate the long-term (15 years) impact of tillage and residue management experiment (LT&RE) initiated in 2006 on soil quality index (SQI) and to establish the quantitative relationship between the SQI and crops yield under various crop establishment practices. Experiment consisted of six treatment combinations including LT&RE namely, (i) conventional tillage without residue (CT − R), (ii) conventional tillage with residue incorporation (CT + R), (iii) reduced tillage without residue (RT − R), (iv) reduced tillage with residue incorporation (RT + R), (v) zero tillage without residue (ZT − R), and (vi) zero tillage with residue retention (ZT + R). The SQI was used as an instrument based soil physical [bulk density (BD), soil penetration resistance (SPR) and infiltration rate (IR)], chemical [soil pH (pH 1:2), electrical conductivity (EC 1:2), soil organic carbon (OC) available nitrogen (N), phosphorus (P), potassium (K), iron (Fe), manganese (Mn), copper (Cu) and zinc (Zn)], and biological [microbial biomass carbon (MBC), alkaline phosphatase activity (ALP), and dehydrogenase activity (DHA)], properties as these are very useful indicators of soil's functions, fertility and agronomic productivity. Soil samples were collected from 0–15 and 15–30 cm soil depth from each treatment after harvesting of wheat in 2021 and 2022. The ZT + R treatment exhibited the lowest bulk density (1.45 Mg m−3) and soil penetration resistance (1306.02 KPa) at surface soil, resulting in higher infiltration rates (7.80 mm h−1). Adoption of LT&RE led to a notable increase (15.8–25.7%) in soil organic carbon (SOC) stock across all the treatment combinations compared to CT-R. The enhanced SOC and better physical soil conditions increased microbial activities. The ZT + R treatment had the highest levels of MBC (271.63 mg kg−1 soil), alkaline phosphatase (187.08 μmol p-nitrophenol g−1 h−1), and dehydrogenase activity (122.00 μg TPF g−1 24 h−1). Despite a significant increase (3.8 and 6.9%) in wheat yield, a notable decrease in rice yield (10.5 and 16.7%) was recorded, leading to 2.9 and 6.2% yield reduction in RWS under RT and ZT treatments, respectively. Addressing the decline in rice yield, improved management of direct seeded rice (DSR) in RT/ZT system, or the crop diversification of long-term DSR with suitable alternative crops in rainy season under LT&RE are recommended strategies. [Display omitted] • Conservational tillage (reduced/zero) and residue management (incorporation/retention) is necessary to sustain soil health. • Assessed soil quality index (SQI) after 15 years of conservational tillage and residue management. • Derived correlation between crop yield and SQI in RWS for surface and sub-surface soil. • Conservational tillage and residue management enhanced SQI by 82% -178%. • 7.5-16.7% lesser DSR yield suggests more pronounced impact of planting method and crop management rather than soil quality. [ABSTRACT FROM AUTHOR]

The primary driver of increasing atmospheric concentrations of nitrous oxide (N 2 O) is the use of organic and synthetic fertilizer to increase agricultural crop production. Current global estimates are based on IPCC N 2 O emission factor (EF) calculations, although there are shortcomings as many of the N 2 O EFs are derived from measurements during the cropping season. These neglect the fallow season, and do not adequately account for double or even triple cropping systems or legacy effects on soil N 2 O emissions in the following year. In this study, we assessed the legacy effect of fertilization on soil N 2 O fluxes using data from a long-term double-cropping field experiment with summer maize and winter wheat in rotation, in which no nitrogen (N; NN) and balanced manure with synthetic N (MN) fertilized treatments were switched to allow an assessment of legacy effects. Based on high-frequency measurements of N 2 O and previous data, we calculated that the historical N fertilization, or legacy effect, explained 23 % of the annual flux of 0.81 kg N ha -1  yr -1 in the first season of observation. In the following three seasons, the legacy effect of the previous N fertilization regime decreased to a negligible level, with N 2 O emissions mainly driven by in-season fertilization. Our data show that, on average, the seasonal EF for N 2 O was about 0.11 % higher in response to the previous N fertilization. Our study indicates that the current N 2 O EF may severely underestimate emissions because studies ignore legacy effects on N 2 O emissions from zero N plots and only compare zero N with N fertilization treatments for a given season or year to derive seasonal or annual N 2 O EF., Competing Interests: Declaration of competing interest The authors declare no conflict of interest., (Copyright © 2024 Elsevier B.V. All rights reserved.)

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Soil P testing has been widely used to predict crop yields, P uptake, and fertilizer demands in agriculture. Diffusive gradients in thin films (DGT) provides a zero-sink soil P test which mimics diffusion-controlled plant uptake and has previously been found to predict P availability to crops better than conventional quantity-based P tests in highly weathered Australian, though not in European soils. Here we tested the performance of DGT and the Austrian and German standard P quantity test calcium acetate lactate (CAL) to explain the variation of crop yield and P uptake response of winter wheat (Triticum aestivum L.) and spring barley (Hordeum vulgare L.) in long-term P fertilization experiments at four different sites in eastern Austria. Phosphorus extracted with DGT (P-DGT) and CAL (P-CAL) correlated well in similar soils but not across sites with large variation in soil and site properties such as carbonate equivalent and water availability. The predictive power of DGT for barley (R2 = 0.42) and wheat grain yield (R2 = 0.32), and P uptake in wheat grains (R2 = 0.36) was clearly superior to that of the CAL, and less dependent on soil properties. The better performance of DGT compared to the quantity test is consistent with diffusion-limited P uptake in the water-limited cultivated soils of eastern Austria. The critical values of P deficiency derived from the Mitscherlich-type fits for barley and wheat at 80% relative yield are 64.9 and 26.2 µg L−1, respectively, consistent with differential P demands of the crops. [ABSTRACT FROM AUTHOR]

No-tillage systems are able to reduce the negative effects of agricultural intensification on soil properties. However, knowledge of long-term impacts of no-tillage systems on soil properties is insufficient. It is essential to know which soil quality indicators are the most sensitive to management practices in each particular environment. Therefore, the objective of this work is to determine which soil quality properties are more sensitive to the impact of two tillage systems in a vertic Argiaquoll soil from Buenos Aires, Argentina. This work started in 2006 and included crop rotation and tillage systems, including both tillage and no-tillage. Physical and chemical properties were measured in three consecutive years (2013–2015) at two depths (0–10 cm and 10–20 cm). The tillage system modified soil physical and chemical properties, mainly in the surface layer. No-tillage showed significantly higher bulk density (2013–2015 p

In einem Feldversuch am Standort Bernburg (Sachsen-Anhalt) wurde untersucht, wie sich Anbausysteme (a1 konventionell, a2 und a3 ökologisch) in zwei Nährstoffstufen auf die Diversität (Shannon - Index), und die Individuenzahlen der Unkräuter insgesamt und Mohn auswirken. Auf Grundlage von Bewirtschaftungs- und Ertragsdaten wurde weiterhin der Energiegewinn berechnet. Es ergaben sich Hinweise, dass auch dieser Parameter den Deckungsgrad beeinflusst und thermodynamische Abhängigkeiten auch in Agrar-Ökosystemen deutlich werden.

Studies have found that the increase in differences between the amount of energy subsidies invested in agrobiocenoses and alienated from them over a 105-year period changes the direction of biochemical processes of organic matter transformation, which leads to significant losses of organic carbon reserves, which amount to 17.5 t/ha in highly degraded soils, 7.3 t/ha in poorly cultivated soils, and in highly cultivated increases them by 2.8 t /ha, respectively, compared with the initial content. Long-term use of arable land affects the qualitative characteristics of the state of organic matter of sod-podzolic soil, which are expressed in a change in the ratio of the peripheral and central parts, the enrichment of humus with nitrogen. The humus substances of medium (57%) and highly cultivated soils (54%) are characterized by the highest degree of participation of peripheral groupings in the construction, and the least highly degraded (29%).

Soil organic matter (SOM) consists of various labile and stable fractions, which are differently influenced by agricultural activities and land-use change. This study, aimed at investigating the feasibility of achieving 4p1000 goals on conventionally tilled plough-land, was carried out in a 42 years-old long-term field experiment (LTE), in which the effect of three farmyard manure (FYM) doses and the FYM equivalent NPK mineral fertiliser rates can be examined, together with that of mineral fertiliser with and without ploughed-in plant residues. The soil total organic carbon (SOC) and nitrogen (SN) and the labile hot-water soluble C (HWC) and N (HWN) fractions were determined (0–0.3 m) and used as indicators. The parameters of the tilled area were compared with those of a grassland area with similar characteristics. The suitability of these parameters for use as soil quality indicators (SQI) was also examined in terms of soil fertility. The results showed that the most sensitive fraction for the detection of treatment effects were HWC and HWN. Increases in these labile organic fractions were significantly related to the gains of SOC stocks. Based on the close correlation between these factors and both SOC and crop yield it is recommended that they should be used as indicators for the prediction of changes in SOC and in studies on soil fertility or soil quality. The initial C stock of 40.46 Mg ha−1 became 40.27–47.05 Mg ha−1 on the tilled soil after four decades, while on the grassland it rose to 69.31 Mg ha−1. The carbon sequestration rate (CSR) in the various fertilisation systems exhibited the following order: plant residue incorporation >FYM addition > mineral fertilisation (0.147–0.156, 0.101–148 and –0.021–0.065 Mg ha−1 yr−1, respectively), while an outstandingly high value of 0.687 Mg ha−1 yr−1 was recorded for the grassland. Despite the fact that the carbon sequestration potential (CSP) remained high (55.36–62.48%), the achievement of 4 per 1000 aims can only be ensured in treatments involving high rates of organic matter and only in the short term.

Addition of organic amendments is a commonly used practice to offset potential loss of soil organic matter from agricultural soils. The aim of the present study was to examine how long-term addition of organic matter affects the abundance of different soil biota across trophic levels and the role that the quality of the organic amendments plays. Here we used a 17-year-old fertilization experiment to investigate soil biota responses to four different organic fertilizers, compared with two mineral nitrogen fertilizers and no fertilization, where the organic fertilizers had similar carbon content but varied in their carbon to nitrogen ratios. We collected soil samples and measured a wide range of organisms belonging to different functional groups and trophic levels of the soil food web. Long-term addition of organic and mineral fertilizers had beneficial effects on the abundances of most soil organisms compared with unfertilized soil, but the responses differed between soil biota. The organic fertilizers generally enhanced bacteria and earthworms. Fungi and nematodes responded positively to certain mineral and organic fertilizers, indicating that multiple factors influenced by the fertilization may affect these heterogeneous groups. Springtails and mites were less affected by fertilization than the other groups, as they were present at relatively high abundances even in the unfertilized treatment. However, soil pH had a great influence on springtail abundance. In summary, the specific fertilizer was more important in determining the numerical and compositional responses of soil biota than whether it was mineral or organic. Overall, biennial organic amendments emerge as insufficient, by themselves, to promote soil organisms in the long run, and would need to be added annually or combined with other practices affecting soil quality, such as no or reduced tillage and other crop rotations, to have a beneficial effect.

Addition of organic amendments is a commonly used practice to offset potential loss of soil organic matter from agricultural soils. The aim of the present study was to examine how long-term addition of organic matter affects the abundance of different soil biota across trophic levels and the role that the quality of the organic amendments plays. Here we used a 17-year-old fertilization experiment to investigate soil biota responses to four different organic fertilizers, compared with two mineral nitrogen fertilizers and no fertilization, where the organic fertilizers had similar carbon content but varied in their carbon to nitrogen ratios. We collected soil samples and measured a wide range of organisms belonging to different functional groups and trophic levels of the soil food web. Long-term addition of organic and mineral fertilizers had beneficial effects on the abundances of most soil organisms compared with unfertilized soil, but the responses differed between soil biota. The organic fertilizers generally enhanced bacteria and earthworms. Fungi and nematodes responded positively to certain mineral and organic fertilizers, indicating that multiple factors influenced by the fertilization may affect these heterogeneous groups. Springtails and mites were less affected by fertilization than the other groups, as they were present at relatively high abundances even in the unfertilized treatment. However, soil pH had a great influence on springtail abundance. In summary, the specific fertilizer was more important in determining the numerical and compositional responses of soil biota than whether it was mineral or organic. Overall, biennial organic amendments emerge as insufficient, by themselves, to promote soil organisms in the long run, and would need to be added annually or combined with other practices affecting soil quality, such as no or reduced tillage and other crop rotations, to have a beneficial effect. [ABSTRACT FROM AUTHOR]

Understanding the relationship between soil organic carbon (SOC) storage and nitrous oxide (N 2 O) fluxes is crucial for sustainable land management. In this study, we examined this relationship in different cropping systems, including annual cropping systems with a legacy of varying durations (3 versus 6 years) of grasslands and continuous grassland. The aim was to investigate (1) the effect of contrasting management practices on SOC storage and N 2 O emissions under field conditions and (2) to elucidate the drivers of N 2 O emissions under controlled conditions. Our findings showed that despite the influence of management practices on SOC stocks, no trade-off was observed between SOC storage at two different depths (10 and 30 cm) and N 2 O emissions. Furthermore, we found that SOC chemical signature, soil physical characteristics, and denitrifier activity, rather than SOC content and denitrifier abundances, were the primary factors determining N 2 O emission potential. It is interesting to note that although functional gene abundances were related to denitrifier activities, they did not show a direct correlation with N 2 O emissions. This suggests that environmental factors and microbial activity play a more substantial role in determining N 2 O emissions than denitrifier abundances. The inclusion of temporary grassland in a crop rotation had a positive impact on SOC stocks, either by improving or maintaining their levels. However, as a trade-off the introduction of temporary grassland also led to higher N 2 O emissions. These increased emissions were not directly associated with the amount of SOC stored in soil but rather with changes in soil physical and chemical conditions. Our research emphasizes the importance of understanding the complex relationships among soil characteristics, management techniques, and N 2 O emissions to develop practical mitigation plans for building more sustainable agricultural systems. [Display omitted] • Management practices had a significant impact on soil organic carbon (SOC) stocks. • No tradeoff was observed between the storage of carbon and the emissions of N 2 O. • Introduction of temporary grasslands, did not lead to elevated N 2 O emissions. • N 2 O emissions were related to soil physical and chemical conditions, rather than changes in the abundance of denitrifiers. [ABSTRACT FROM AUTHOR]

The polyfactorial long-term field experiment was conducted in 1983 on a calcareous chernozem soil in Hungary (Debrecen-Látókép experimental farm) to determine the long-term effect of different doses of chemical fertilizers and irrigation on the yield, nutrient uptake of maise (in monoculture production) and on soil parameters. Our aim was to analyse and compare the changes of soil chemical and microbiological caracteristics for 33 years NPK fertilizer application either in irrigated and or in non irrigated version. Soil pH, humus, nutrient content and some soil microbiological parameters were analyzed. The microbiological parameters sightly, the chemical parameters of soil significantly influenced by long term application of NPK fertilizers. In fertilized plots: the pH decreased, humus content increased. The availability of supplied nutrients, NPK improved, while non-supplied macronutrients, calcium and magnesium significantly decreased in fertilized plots compared to control. The significantly decrease in calcium content call attention, that the same effect in acidic sandy soil might be particularly harmful. In fertilized plots the number of bacteria tended to decrease, while the number of microscopic fungi and saccharase enzime activity significantly enhanced. The irrigation did not cause significant changes of measured microbiological parameters.

In a long-term field experiment in the western part of the nonchernozemic zone of Russia (Smolensk oblast) on sandy loamy soddy-podzolic soil (Albic Glossic Retisol (Loamic)), the comparison of the effect of various rates and combinations of organic and mineral fertilizers revealed their efficiency in all the studied variants, except for the separate application of phosphorus fertilizers. It was found that the organomineral system—N90P90K90 + manure 9 t/ha—provided a deficit-free humus balance in the soil and stable productivity of crops (average for 30 years) at the level of 3.79 tons of forage units per hectare, or 37% higher than the control (without fertilizers). The mineral fertilizer system—N90P90K90—by the end of the fourth crop rotation was not inferior in the productivity to the organomineral system, but it led to a decrease in the soil humus content and pHKCl. The organic system with an annual manure rate of 9 t/ha occupied an intermediate position with respect to the crop rotation productivity (3.41 t/ha of forage units), as well as with respect to the soil fertility reproduction. A reliable increase in crop yield in the aftereffect was only recorded in the variants of organic and organomineral fertilizer systems, i.e., when soils were saturated with organic matter from manure. The soil in these variants was characterized by the high total number of microorganisms. [ABSTRACT FROM AUTHOR]

Despite recent technological advances in molecular ecology, DNA extraction from soil remains a crucial step when quantifying and characterizing soil microbial communities. Potential biases could hamper fundamental understanding of the dynamic relationships between soil properties and microorganisms under different agricultural practices. In this study, we compared four different DNA extraction methods for their ability to discriminate microbial communities of an arable soil subjected to different fertilization managements for more than 50 years (Ultuna, Sweden). The abundance and the diversity of bacteria, archaea and fungi were studied using qPCR and molecular fingerprints, respectively. Overall, the choice of DNA extraction method had a more pronounced effect on the fungal and archaeal communities in comparison to bacterial ones. The assessment of the microbial diversity was more sensitive to DNA extraction methods in comparison with the quantification of the abundances. The DNA extraction method clearly affects the intensity of the correlations between the abundance and/or diversity of microbial communities and environmental variables (C, N and pH) according to the targeted taxon. This study highlights that long‐term effects can be offset by biases in DNA extraction methods. Highlights: Using different DNA extraction methods may alter soil microbial survey.Average DNA concentrations vary from 1 to 3 μg.g−1 according to the extraction method.Gene copies numbers vary up to 2 orders of magnitude among DNA extraction methods.Fungal communities diversity descriptors were the most affected by DNA extraction [ABSTRACT FROM AUTHOR]

Increased inorganic nitrogen (N) and phosphorus (P) additions expected in the future will endanger the biodiversity and stability of agricultural ecosystems. In this context, a long-term fertilizer experiment (37 years) was set up in the black soil of northeast China. We examined interaction impacts of elevated fertilizer and host selection processes on arbuscular mycorrhizal fungi (AMF) communities in wheat rhizosphere soil using the Illumina MiSeq platform. The soil samples were subjected to five fertilization regimes: no fertilizer (CK) and low N (N1), low N plus low P (N1P1), high N (N2), and high N plus high P (N2P2) fertilizer. Long-term fertilization resulted in a significant shift in rhizosphere soil nutrient concentrations. The N fertilization (N1 and N2) did not significantly change rhizosphere AMF species diversity, but N plus P fertilization (N1P1 and N2P2) decreased it compared with CK. Non-metric multidimensional scaling showed that the rhizosphere AMF communities in CK, N1, N2, N1P1 and N2P2 treatments were distinct from each other. The AMF communities were predominantly composed of Glomeraceae, accounting for 30.0–39.1% of the sequences, and the relative abundance of family Glomeraceae was more abundance in fertilized soils, while family Paraglomeraceae were increased in N1 and N2 compared with CK. Analysis shown that AMF diversity was directly affected by soil C:P ratio but indirectly affected by plant under long-term fertilization. Overall, the results indicated that long-term N and P fertilization regimes changed rhizosphere AMF diversity and community composition, and rhizosphere AMF diversity was both affected by soil C:P ratio and plant.

Carbon sequestration has been proposed as a way to mitigate the impact of CO2 on the climate. At the COP21, the ‘4 per 1000 Soils for Food Security and Climate’ initiative was launched with the goal to increase global soil organic carbon (SOC) stocks by 4‰ per year. The Thyrow long-term field experiment DIV.2 was chosen to determine the feasibility of this 4 per 1000 goal under the dry and sandy conditions in Eastern Germany. The effects of different fertilizing regimes on SOC contents and winter rye yields were investigated. Winter rye is a representative crop for the region and grown as a monoculture in the experiment. The 4 per 1000 goal was achieved in all treatments including the unfertilized control, although ploughing takes place and straw is removed every year. The highest carbon sequestration of up to 0.5 t ha−1 a−1 was provided by a combination of mineral and manure fertilization. In three out of four years, no yield difference was observed between mineral-only fertilization (120 kg ha−1 N) and a combination of mineral and organic N (97.4 kg ha−1 plant available N) fertilization. Yields increased over the years in the treatment with pure organic N and decreased in all other treatments.

Increased inorganic nitrogen (N) and phosphorus (P) additions expected in the future will endanger the biodiversity and stability of agricultural ecosystems. In this context, a long-term fertilizer experiment (37 years) was set up in the black soil of northeast China. We examined interaction impacts of elevated fertilizer and host selection processes on arbuscular mycorrhizal fungi (AMF) communities in wheat rhizosphere soil using the Illumina MiSeq platform. The soil samples were subjected to five fertilization regimes: no fertilizer (CK) and low N (N1), low N plus low P (N1P1), high N (N2), and high N plus high P (N2P2) fertilizer. Long-term fertilization resulted in a significant shift in rhizosphere soil nutrient concentrations. The N fertilization (N1 and N2) did not significantly change rhizosphere AMF species diversity, but N plus P fertilization (N1P1 and N2P2) decreased it compared with CK. Non-metric multidimensional scaling showed that the rhizosphere AMF communities in CK, N1, N2, N1P1 and N2P2 treatments were distinct from each other. The AMF communities were predominantly composed of Glomeraceae, accounting for 30.0–39.1% of the sequences, and the relative abundance of family Glomeraceae was more abundance in fertilized soils, while family Paraglomeraceae were increased in N1 and N2 compared with CK. Analysis shown that AMF diversity was directly affected by soil C:P ratio but indirectly affected by plant under long-term fertilization. Overall, the results indicated that long-term N and P fertilization regimes changed rhizosphere AMF diversity and community composition, and rhizosphere AMF diversity was both affected by soil C:P ratio and plant. [ABSTRACT FROM AUTHOR]

The aim of this work was to estimate the changes in contents of different sulfur (S) fractions in soils under lowering inputs of S from emissions together with the influence of organic and mineral fertilizing. Soil samples from long-term field experiments were used for this purpose. The samples were taken from 10 sites from precise long-term field experiments with different soil-climatic conditions in the Czech Republic. The samples were analyzed using the following fractionation: i) water soluble S (H2O extracts), ii) sorbed S (0.032M NaH2PO4 extracts) and iii) S occluded with carbonates (1M HCl extract). Furthermore, the concentration of total S (Stot) and organic S (Sorg) was determined. Soil samples were taken in the years 1981 and 2007. During 26 years a decreases of Stot by about 3-8%, water soluble S by 65-68 % and sorbed S by 39-44 % was observed in the topsoil of the evaluated soils. Furthermore, a low increase in the organic S content (Sorg) was observed. The estimated ratio of Sorg reached 78.7-80.9% from Stot in the year 1981 and 87.7-89.8 % in 2007. Farmyard manure (40 t.ha-1) applied every 4 years did not have a significant influence on S fractions and Stot contents in soils. Intensive S fertilizing increased Stot and mobile S forms contents in the soils.

Arbuscular mycorrhizal fungi (AMF) are indicators of soil health and are associated with various soil benefits, primarily linked to glomalin accumulation from hyphal turnover. However, the direct connection between glomalin-related soil protein (GRSP) and AMF has been questioned. The study aimed to investigate the correlation between different fractions of GRSP and fatty acid fractions in soil, as well as the impact of conservation agriculture practices on AMF biomass and GRSP content. Findings revealed a positive correlation between easily extractable (EE) GRSP and phospholipid fatty acid (PLFA) 16:1ω5, while no significant correlations were found for difficultly extractable (DE) or total GRSP fractions. These results highlight the complexity of GRSP dynamics and the need for further research on different fractions and their relation to AMF biomass. Additionally, the study demonstrated that mechanical soil management had a greater impact on AMF hyphal biomass and EE-GRSP compared to residue management. Direct seeding, a reduced tillage approach, led to higher hyphal biomass and EE-GRSP, indicating AMF sensitivity to tillage intensity. This suggests that tillage practices exert a stronger influence on AMF abundance and GRSP content than residue management. • Methods used to estimate AMF and glomalin pools are decisive in assessing their relation. • Quantification of AMF and GRSP are useful to evaluate soil management strategies. • Signature PLFA was the most sensitive indicator of expected AMF biomass shifts. • AMF biomass, measured by PLFA, was affected more by tillage than residue management. [ABSTRACT FROM AUTHOR]

Nitrogen (N) loss from fertilization in agricultural fields has an unavoidable negative impact on the environment and a better understanding of the major pathways can assist in developing the best management practices. The aim of this study was to evaluate the fate of N fertilizers applied to acidic red soil (Ferralic Cambisol) after 19 years of mineral (synthetic) and manure fertilizer treatments under a cropping system with wheat-maize rotations. Five field treatments were examined: control (CK), chemical nitrogen and potash fertilizer (NK), chemical nitrogen and phosphorus fertilizer (NP), chemical nitrogen, phosphorus and potash fertilizer (NPK) and the NPK with manure (NPKM, 70% N from manure). Based on the soil total N storage change in 0–100 cm depth, ammonia (NH3) volatilization, nitrous oxide (N2O) emission, N plant uptake, and the potential N leaching loss were estimated using a mass balance approach. In contrast to the NPKM, all mineral fertilizer treatments (NK, NP and NPK) showed increased nitrate (NO3−) concentration with increasing soil depth, indicating higher leaching potential. However, total NH3 volatilization loss was much higher in the NPKM (19.7%) than other mineral fertilizer treatments (≤4.2%). The N2O emissions were generally low (0.2–0.9%, the highest from the NPKM). Total gaseous loss accounted for 1.7, 3.3, 5.1, and 21.9% for NK, NP, NPK, and NPKM treatments, respectively. Estimated N leaching loss from the NPKM was only about 5% of the losses from mineral fertilizer treatments. All data demonstrated that manure incorporation improved soil productivity, increased yield, and reduced potential leaching, but with significantly higher NH3 volatilization, which could be reduced by improving the application method. This study confirms that manure incorporation is an essential strategy in N fertilization management in upland red soil cropping system.

Repeated applications of organic waste products (OWP) are a source of trace elements (TE) inputs to agricultural topsoils. The present study aimed at (i) assessing the effects of repeated OWP inputs on the chemical properties of topsoils in two long-term field experiments (13 and 15 years; calcareous and non-calcareous soils), (ii) evaluating TE phytoavailability and their transfer to grain (winter wheat and maize) and (iii) identifying the underlying factors causing alterations of TE phytoavailability. In both field experiments, receiving compliant or slightly high doses of OWP in compliance with regulations, OWP and soil physicochemical properties and TE concentrations in soils and grains were determined. In situ phytoavailability of TE was assessed at two juvenile crop growth stages by analyzing TE concentrations in shoot plantlets. Depending on the OWP input amount, results showed that compared to the soil receiving no organic amendment, repeated OWP inputs significantly increased soil organic carbon content, pH, cation exchange capacity, total soil Cu, Mo and Zn concentration and the phytoavailability of Mo, while the phytoavailability of Cd, Mn, Ni and Tl was significantly reduced. No notable effect was observed for Cr, Cu, Hg, Pb and Zn phytoavailability. Statistical approaches suggested that due to the repeated OWP applications, increased soil organic carbon content and pH, were likely responsible for decreased TE phytoavailability (e.g., Cd).