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This work demonstrated the feasibility of an industrial-scale aerated static pile composting system for treating one of the common biowastes—soybean curd residue. The mixing ratios of the feedstock were optimized to achieve a carbon–nitrogen ratio and a moisture level in the ranges of 25–35 and 60–70%, respectively. This open-air composting system required 6–7 months to obtain a mature compost. Solvita and seed germination tests further confirmed the maturity of the compost, with 25% compost extract concentration yielding the best germination index in the absence of phytotoxicity. The bacterial and fungal compositions of the compost piles were further examined with metagenomic analysis. Thermoactinomyces spp., Oceanobacillus spp., and Kroppenstedtia spp. were among the unique bacteria found, and Diutina rugosa, Thermomyces dupontii, and Candida taylorii were among the unique fungi found in the compost piles, suggesting the presence of good microorganisms for degrading the organic biowastes. [ABSTRACT FROM AUTHOR]

Knowledge about how on-farm management decisions influence maize residue quantity and quality is limited but necessary to better manage the effects of residue on cropping systems carbon, nutrient turnover, and water dynamics. Our objectives were to i) Quantify the interactive effects of previous crop, nitrogen (N) fertilizer rate, plant density, and hybrid on maize residue quantity and quality characteristics, and ii) Explore relationships and potential trade-offs between residue attributes and grain yield to aid decision making. Experiments were carried out in central Iowa, USA in 2021 and 2022. We evaluated three commercial hybrids across three N fertilizer rates (0, 146, 336 kg N ha−1), and three plant densities (3.6, 7.5, 11.3 plants m−2) in fields with maize or soybean as the previous crop, totaling 54 replicated treatments. Biomass samples were collected at physiological maturity, and 12 residue-related attributes were assessed together with the final grain yield. The experimental factors generated a large variability in maize grain yield (1.5–15.4 Mgha−1), residue amount (2.6–14.1 Mg ha−1), residue CN ratio (33–130), residue N (11–167 kg N ha−1), and residue lignin concentration (1.0–3.6%). Nitrogen fertilizer explained most of the variability in residue quantity and CN ratio while plant density explained most of the variability in residue biochemical composition. Significant interactions among studied factors on residue attributes were few and mostly related to hybrids by plant density and previous crop by N rate interactions. Our results indicated that the higher the grain yield, the higher the residue quantity (r = 0.79), the residue lignin concentration (r = 0.46), and the lower the residue CN ratio (r = −0.51). Grain yields lower than 8 Mg ha−1 generated comparatively higher residue quantities (grain harvest index < 0.50), while the opposite occurred at grain yields above 8 Mg ha−1. Management practices that resulted in high grain yields generated residues with low CN ratio but high lignin concentration, indicating a tradeoff in residue quality. The observed large effects of management on residue quality and quantity imply that there are opportunities to manipulate residue attributes via management for maximizing profitability and soil health. • Management practices generated 1.4–15-fold variability in residue attributes. • Nitrogen fertilizer explained most of the variation in residue quantity and CN ratio. • Plant density explained most of the variation in residue biochemical composition. • Practices that increased grain yield resulted in a low residue CN ratio but high lignin concentration. [ABSTRACT FROM AUTHOR]

This work demonstrated the feasibility of an industrial-scale aerated static pile composting system for treating one of the common biowastes—soybean curd residue. The mixing ratios of the feedstock were optimized to achieve a carbon–nitrogen ratio and a moisture level in the ranges of 25–35 and 60–70%, respectively. This open-air composting system required 6–7 months to obtain a mature compost. Solvita and seed germination tests further confirmed the maturity of the compost, with 25% compost extract concentration yielding the best germination index in the absence of phytotoxicity. The bacterial and fungal compositions of the compost piles were further examined with metagenomic analysis. Thermoactinomyces spp., Oceanobacillus spp., and Kroppenstedtia spp. were among the unique bacteria found, and Diutina rugosa, Thermomyces dupontii, and Candida taylorii were among the unique fungi found in the compost piles, suggesting the presence of good microorganisms for degrading the organic biowastes.

Carbon and nitrogen are two of the most important elements found in soil structure and the relationship between them has a special relevance on soil characterization. This relationship is known as carbon-nitrogen ratio (C/N ratio) and indicates the rate of decomposition of organic matter. Degradation of organic matter will certainly modify the C/N ratio, and this modification is related to the existing microorganisms in soil. The present study follows the evolution of the C:N ratio in a calcaric alluvial soil from Buzau county used for organic tomato cultivation and subjected to a microbial treatment based on Beauveria bassiana inoculants. The experimental scheme includes three variants: (1) untreated soil, uncultivated (control); (2) untreated soil, cultivated with Florina 44 tomato variety; (3) soil treated with microbial inoculants, cultivated with Florina 44 tomato variety. Each variant was observed on two different lots and in two moments (autumn 2019 and autumn 2020). The soil samples were taken from topsoil, dried at room temperature, and analysed using the CHNS elemental analyser for C and N determinations. Regarding the C:N ratio, the results pointed out that there are some differences that correlate with the use of microbial inoculants in tested variants. [ABSTRACT FROM AUTHOR]

This study was conducted to elucidate how changes in critical soil quality characteristics relate to continuous rice cultivation and changes in cropping systems and fertilization in South China over the time span 1980 to 2017. Soil pH, soil organic matter (SOM), total nitrogen (TN), available phosphorus (AP) and potassium (AK) were determined for the samples taken in 2017 and compared to results from the paired samples collected in 1980 by grouping all samples into four cropping systems: continuous paddy fields, new paddy fields developed from uplands, continuous uplands, and new uplands developed from paddy soils. The results show a significant increase in soil pH, AP and AK in all cropping systems, which was, however, coupled with low fertilizer use efficiency. Additionally, a significant increase in SOM came with new paddy soils, whereas a little SOM accumulation and a significantly weakened correlation of TN to SOM occurred in continuous paddy soils. Both low fertilizer use efficiency and deteriorated soil C sequestration function imply a sub-health status of continuous paddy soils. The changes in cropping systems and fertilization, which essentially resulted from expeditious economic growth, should be responsible for the dynamics of C and N and the consequences to soil quality. More experimental studies on balanced fertilization vs. local commonly used fertilization are suggested to probe the mechanisms underlying the C and N dynamics in paddy soils.

Biofloc technology (BFT) is a novel modern aquaculture farming technique used to reduce toxic nitrogen concentration, act as in situ food source and eradicate pollutants using carbon and therefore to control C:N ratio in an aquaculture system. In this study, effect of different C:N ratios of a biofloc based system on water quality such as the level of Total ammonia nitrogen (TAN) nitrite-nitrogen (NO 2 − –N) and nitrate nitrogen (NO 3 − –N) were explored. Further, the growth and immunity status of shrimp L. vannamei under the influence of different C:N ratios were evaluated. Two of the C:N ratios (15 and 20) could significantly (P < 0.05) reduce TAN, NO 2 -N and NO 3 -N levels (0.456 ± 0.01, 0.145 ± 0.09, and 0.102 ± 0.02 ppm) compared to control (1.45 ± 0.1, 0.749 ± 0.14 and 0.675 ± 0.16 ppm). Large variations in the frequency distribution of operational taxonomic units (OTUs) for the bacterial community in water with different C:N ration (BFT) and control were observed. Vibrios often considered as opportunistic pathogens, where the most dominant bacterial flora of water in control (79%) and C:N5 (37%) group. In C:N10, Thauera (62%) was most represented genus. Similarly, Attheyaceae (56%), followed by Peridiniaceae (30%) were the most dominant groups in C:N15 treatment. The diversity of bacterial flora was more spread in C:N20 treatments with Psychrobacter (26%), Proteobacteria (25%) and Peridiniaceae (20%) as the major groups. The trend of Vibrio dominance decreased with the increase in C:N ratios and thus confirming the dominance of heterotrophic bacteria in high C:N ratio groups. Upon challenge with pathogens, shrimps from C:N10, C:N15 and C:N20 groups showed significantly higher survival (P < 0.05) compared to the C:N5 and control group. Similarly, better growth rate was also observed in BFT tanks compared to control both during the culture and at harvest. Comparatively higher expression of four immune-related genes (ras-related nuclear gene (RAN), serine proteinase gene (SP), prophenoloxidase activating enzyme (PPAE), and crustin were observed in different C:N ratio ponds than control and these were in increasing trend with the C:N ratio. Gene expression analysis showed that the transcripts of those immune genes were significantly increased among all C:N treatments than that of control. Overall, these findings demonstrated that with optimum C:N ratio, BFT can be used to optimize the bacterial community composition for both optimal water quality and optimal shrimp health. This study thus indicates the possibility of obtaining better performance of L. vannamei culture with proper adjustment of C:N ratio in a biofloc based system. [ABSTRACT FROM AUTHOR]

The use of coffee grounds in crop fields were evaluated in terms of crop growth enhancement, soil improvement, and weed control during four successive cropping seasons for two years. Six summer and three winter green manure crops were grown from June 2009 to May 2011. In the first cropping season, the growth of all green manure crops was significantly inhibited by the application of 10 kg m–2 of coffee grounds. However, the inhibitory effects spontaneously diminished after the second cropping season (about 12 months later), and the growth of guinea grass, sorghum and sunflower was about 2-fold higher than that of the control. The application of horse manure at 10 kg m–2 effectively alleviated the inhibitory effects, even though the high concentration of coffee grounds was included. Although top dressing application of coffee grounds at 16 kg m–2 permitted weed control, the impact maintained enough only for half a year. Coffee grounds application effectively increased both carbon and nitrogen contents of soil and reduced CN ratio. The soil amendment effects were significantly higher in terms of nitrogen enrichment and CN ratio improvement as compared with the horse manure application. These results indicated that coffee grounds are useful to enhance long term crop growth, short duration weed control, and soil improvement in agricultural fields by considering the inhibitory effects on the plant growth for half year after the application. Agricultural use of coffee grounds was also discussed in term of fallow periods in crop rotation.

To explore the question how litter and macrofauna feces respond to temperature and how respiration differs for litter with a different CN ratio, we compared the decomposition rates of leaf litter (Alnus glutinosa, Salix caprea, and Acer campestre) and isopod (Armadillidium vulgare) feces produced from the same litter in response to three constant (8, 16, and 24 °C) and one fluctuating (first week 8 °C, the other week 24 °C) temperatures in a 50 week laboratory experiment and in a field trial. Microbial respiration of litter with lower CN ratio (alder and willow) was significantly higher than respiration of feces, no significant difference was found for maple litter with higher CN ratio. This was supported by field litter bag experiments where alder and willow litter decomposed faster than feces but the opposite was true for maple litter. Litter respiration was significantly affected by temperature but feces respiration was not. Fluctuating temperature caused either lower or equal respiration as compared to mean constant temperature. The content of phenolics was significantly higher in intact litter in comparison with decomposed litter and feces, either fresh or decomposed. The CN ratio decreased as litter turned to feces in maple and alder litter but increased in willow litter. In conclusion, microbial respiration of both litter and feces were substantially affected by litter quality; the litter was more sensitive to temperature than feces.

To understand why excrements of soil macrofauna often decompose more slowly than leaf litter, we fed Bibio marci larvae the litter of tree species differing in litter quality ( Alnus glutinosa , Salix caprea , and Quercus robur ) and then measured respiration induced by litter and excrements. We also measured respiration induced by the same litter artificially modified to mimic faunal effects; the litter was modified by grinding, grinding with alkalinization to pH = 11, grinding with coating by kaolinite, and grinding with both alkalinization and coating. Decomposition of excrements tended to be slower for willow and was significantly slower for oak and alder than for the corresponding litter. With oak, decomposition was slower for all artificially modified litter than for non-modified litter. The reduction in the decomposition was similar for excrements and for alder and willow litter that was ground, coated, and alkalinized. In alder, a similar reduction was found in ground and alkalinized litter. 13 C NMR indicated that gut passage increases aliphatic components and decreases polysaccharides. Pyrolysis indicated that gut passage increases the ratio of guaiacyl to hydroxymethyl derivatives in lignin. Our findings indicate that the decreased decomposition rate of excrements might result from the removal of easily available polysaccharides, the increase in aliphatic components, an increase in the resistant components of lignin, the accumulation of microbial cell walls, and the binding of nitrogen into complexes with aromatic components. Several of these mechanisms are supported or determined by litter alkalinization during gut passage. [ABSTRACT FROM AUTHOR]

The biomass of Zostera marina in the temperate coastal zone has seasonal variations in their dry weight, with a peak during the spring season when a large section of the shoots develops reproductive organs. However, the period of high biomass is only short-term, after which large numbers of reproductive shoots drastically disappeared. Dislodgement is an important fate of the reproductive biomass. The fraction of biomass that reaches the deep sea contributes to carbon sequestration, however the processes of dislodgement and transportation of reproductive shoots of Z. marina has been rarely studied. Here, based on a monitoring survey of two Z. marina meadows, we estimated the net loss of biomass, including their reproductive one. In addition, microbial decomposition was assessed by dark incubation to evaluate the fate of the dislodged biomass. The apparent loss of biomass from the Z. marina meadows in the "Declining Period", defined with the most rapid decrease in biomass, accounted for 82–100% of the biomass at the initial time-point of this period. By subtracting the biomass production from the apparent loss, we calculated the net loss of biomass in the Declining Period, accounting for 14–81% of the annual production. Approximately half of the biomass loss in the Declining Period was attributed to reproductive biomass, suggesting that dislodgement of reproductive shoots is an important fate of photosynthetic products of Z. marina. The carbon to nitrogen (CN) ratio of the reproductive shoots was found to be significantly higher than that of vegetative shoots. Since nitrogenous materials are relatively labile, we expected a lower bioavailability of reproductive shoots. However, microbial decomposition did not reflect the CN ratio, probably due to the heterogeneity of nitrogenous materials and/or due to the contribution of carbohydrates consisting mostly of non-nitrogenous compounds. [Display omitted] • Biomass disappeared in declining period accounted for 14–81% of annual productivity. • Half of the biomass that disappeared in declining period is reproductive shoots. • CN ratio of reproductive shoots was higher than vegetative ones. • Microbial decomposition did not reflect CN ratio. [ABSTRACT FROM AUTHOR]

Elevated atmospheric CO 2 concentrations [CO 2 ] are known to change plant growth by stimulation of C 3 photosynthesis and by reduction of transpiration of both C 3 and C 4 crops. In comparison to the information on above ground plant responses only limited knowledge exists on the response of root growth of arable crops to elevated [CO 2 ] which is particularly true for temperate crop species under real field conditions. A free air CO 2 enrichment (FACE) study (550 ppm at daylight hours) was carried out in a crop rotation of winter barley, sugar beet and winter wheat repeated twice in the course of six years on a sandy loam soil at Braunschweig, Northern Germany. Winter barley and sugar beet were included for the first time in a FACE study. A possible interaction with restricted nitrogen (N) supply was studied by fertilizing the CO 2 treatment plots with adequate and 50% of adequate N supply. Fine root samples were taken in the plough layer and below at 3–4 sampling dates during the vegetation period and root dry matter (excluding sugar beet storage root), shoot root ratio, root length density, specific root length and root tissue composition (CN ratio) were determined. Main effects of elevated [CO 2 ] on the investigated variables were slightly significant. Significant CO 2 effects were observed in interaction with the sampling date. In most cases elevated [CO 2 ] increased root dry matter early in the vegetation period with a maximum growth stimulation of up to 54% as compared to ambient [CO 2 ]. Concomitantly, root length densities were increased in both winter wheat and sugar beet. For winter barley also a significant decrease in root dry weight and significant increase of shoot root ratio was detected at final harvest while such an effect was not significant for sugar beet. Specific root length as an indicator of root morphology was mainly influenced by crop species. As a result, there was no consistent overall effect of elevated [CO 2 ] on biomass partitioning in this study as changes in shoot root ratio only occurred at specific sampling dates indicating a similar stimulation of roots and above-ground biomass due to elevated [CO 2 ]. Nitrogen supply did not alter the effect of elevated [CO 2 ] on any of the root variables apart from CN ratios. A significant increase of root CN ratios in wheat and sugar beet was observed under elevated [CO 2 ], but this effect was much smaller than the effect of N supply. [ABSTRACT FROM AUTHOR]

Three isolates of the entomopathogen Beauveria bassiana along with one strain of Metarhizium anisopliae were cultured on seven media with different carbon/nitrogen (C/N) ratios. The effect of nutrition on virulence of the isolates was evaluated via measurement of colony growth, spore yield, germination speed, conidial C/N ratio and Pr1 (a serine protease) activity. ‘Osmotic stress’ medium produced the lowest colony growth with low numbers of conidia in all isolates. However, these conidia showed a high germination rate and virulence. However, conidial Pr1 activity was low in some isolates. In most but not in all cases conidia from 1% yeast extract, 2% peptone and low (10 : 1) C/N medium had higher Pr1 activity compared with conidia from other media. However, in some instances we could not conclude that there was a relationship among germination rate, conidial Pr1 activity and virulence. C/N ratio of conidia was statistically different among various media and fungal isolates. Conidia with lower C/N ratio generally produced lower LT50 (lowest median lethal time) values (more virulent). Insect-passaged conidia from different media had lower C/N ratio compared with similar conidia from artificial cultures. Therefore, they should be more virulent than in vitro produced conidia. As germination rate, conidial Pr1 activity and C/N ratio are independent of host, it seems that host-related determinants such as insect cuticle and physiology and environmental conditions may influence host susceptibility and therefore fungal isolate virulence towards host insects. [ABSTRACT FROM AUTHOR]

The impact of tree species on soil carbon stocks and acidity in southern Sweden was studied in a non-replicated plantation with monocultures of 67-year-old ash (Fraxinus excelsior L.), beech (Fagus silvatica L.), elm (Ulmus glabra Huds.), hornbeam (Carpinusbetulus L.), Norway spruce (Picea abies L.) and oak (Quercus robur L.). The site was characterized by a cambisol on glacial till. Volume-determined soil samples were taken from the O-horizon and mineral soil layers to 20 cm. Soil organic carbon (SOC), total nitrogen (TN), pH (H2O), cation-exchange capacity and base saturation at pH 7 and exchangeable calcium, magnesium, potassium and sodium ions were analysed in the soil fraction&VeryThinSpace;< 2 mm. Root biomass (<5 mm in diameter) and its proportion in the forest floor and mineral soil varied between tree species. There was a vertical gradient under all species, with the highest concentrations of SOC, TN and base cations in the O-horizon and the lowest in the 10–20 cm layer. The tree species differed with respect to SOC, TN and soil acidity in the O-horizon and mineral soil. For SOC and TN, the range in the O-horizon was spruce > hornbeam > oak > beech > ash > elm. The pH in the O-horizon ranged in the order elm > ash > hornbeam > beech > oak > spruce. In the mineral soil, SOC and TN ranged in the order elm > oak > ash = hornbeam > spruce > beech, i.e. partly reversed, and pH ranged in the same order as for the O-horizon. It is suggested that spruce is the best option for fertile sites in southern Sweden if the aim is a high carbon sequestration rate, whereas elm, ash and hornbeam are the best solutions if the aim is a low soil acidification rate. [ABSTRACT FROM AUTHOR]

Abstract: Nutrition influenced growth, sporulation and virulence of the insect pathogenic fungus, Metarhizium anisopliae. Virulent conidia were produced on susceptible insect hosts, 1% yeast extract, 2% peptone, osmotic stress medium (OSM) and CN 10:1 medium. Several strain independent markers were identified that could be used to predict the virulence of M. anisopliae conidia. Virulent conidia typically had high levels of spore bound Pr1, an important cuticle degrading protease, and high germination rates. We also show for the first time that virulent conidia have an endogenous CN ratio below 5.2:1. Real Time PCR revealed that virulent conidia from insects contained significantly higher levels of transcripts of pr1 A and other pathogenicity-related genes than inoculum from artificial media. Of the artificial media studied, 1% yeast extract medium yielded the most virulent conidia, these had higher levels of transcripts of these pathogenicity-related genes than the least virulent conidia from the high conidia yielding CN 35:1 medium (=SDA), however, the levels were significantly lower than those in insect-derived conidia. Our study shows for the first time that the passaged inoculum is virulent irrespective of the original culture medium or insect host. Virulent conidia were consistently produced on OSM even though growth and sporulation were poor. We postulate that starvation conditions, whether in vivo or in vitro, results in de-repression of Pr1 and that elevated levels of this enzyme enhance fungal virulence. [Copyright &y& Elsevier]

Abstract: Direct application of yard trimmings to agricultural land can benefit soils and crop production, while providing an outlet for handling high volumes of materials at compost facilities. Variability in the composition of yard trimmings can make it difficult to determine appropriate application rates. Our objective was to characterize the chemical composition and variability of yard trimmings generated throughout the spring and summer season at facilities in the Puget Sound region of Washington State. Yard trimmings were sampled from four composting facilities on five dates between April and August 1999. One material contained mostly grass clippings and had higher mean total N (3.2%) than mixed grass and woody materials (1.5–2%). Mean C:N was lower in the grass-rich material (12:1 vs. 15 to 21:1), while mean ammonium concentrations were similar (0.18–0.28%). Variation among facilities was greater than variation over time. The amount of variation observed with other nutrients, pH, EC, or trace elements would not affect use of the yard trimmings in agriculture. Our results suggest that it is possible to characterize yard trimmings adequately for agricultural use. [Copyright &y& Elsevier]

Forested histosols have been found in some cases to be major, and in other cases minor, sources of the greenhouse gas nitrous oxide (N2O). In order to estimate the total national or global emissions of N2O from histosols, scaling or mapping parameters that can separate low- and high-emitting sites are needed, and should be included in soil databases. Based on interannual measurements of N2O emissions from drained forested histosols in Sweden, we found a strong negative relationship between N2O emissions and soil CN ratios ( r2adj=0.96, mean annual N2O emission= ae(− b CN ratio)). The same equation could be used to estimate the N2O emissions from Finnish and German sites based on CN ratios in published data. We envisage that the correlation between N2O emissions and CN ratios could be used to scale N2O emissions from histosols determined at sampled sites to national levels. However, at low CN ratios (i.e. below 15–20) other parameters such as climate, pH and groundwater tables increase in importance as regulating factors affecting N2O emissions. [ABSTRACT FROM AUTHOR]

The aim with the present case study was to detect environmental changes during the isolation of a lake from the Baltic Sea. Elemental and stable-isotope ratios of carbon and nitrogen are presented as well as results of a diatom analysis of a sedimentary sequence from Lake Skären in southeastern Sweden. The dated part of the analysed sequence covers the period c. 8200 to 7000 cal. years BP, i.e., the late Ancylus Lake to early Litorina Sea stages. It is concluded that subtle environmental changes due to fluctuations in input of organic material from different sources cannot be detected by diatom analysis alone, but that chemostratigraphy is an important complement to diatom stratigraphy when interpreting the isolation process. We also conclude that, even though δ[sup 13]C is highly variable in Baltic Sea sediment, it is most useful in isolation studies for recording the contribution of organic carbon derived from benthic macro-algae and/or terrestrial sources, as a proxy for shore displacement. It is especially valuable in combination with the C/N ratio, which seems to be the most unambiguous parameter. The δ[sup 15]N data showed that cyanobacterial blooms in the coastal zone of the early Litorina Sea were probably less pronounced than in the offshore areas of the Baltic Sea. The abrupt increase of Chaetoceros spp. resting spores slightly prior to isolation is interpreted as caused by a eutrophication process during the isolation: it is probably also due to nitrogen deficiency due to denitrification in the coastal areas. [ABSTRACT FROM AUTHOR]

Peat fires in Indonesia are predominantly anthropogenic and intensified by El Niño Southern Oscillation (ENSO)-related droughts. In recent decades, peat fires, which typically occurred in degraded areas (partially/entirely deforested peatlands), released massive amounts of carbon by burning the peat swamp vegetation and peat substrate. However, it could also influence atmospheric nutrient deposition, have a fertilizing effect on peatlands, and enhance their productivity. Little is known about how ENSO-related peat fires would affect the vegetation in times of little or no human impact. It is also unclear whether in the past such an ash-fertilization effect also occurred in the long term and how fires affected peatland carbon sequestration, which is one of their important ecosystem services. In order to understand this, we examine the fire regime, vegetation composition, nutrient status and carbon (C) accumulation rates of the Air Hitam and Sungai Buluh peatlands in Jambi, Sumatra, Indonesia during the Holocene. The results suggest that increased ENSO frequency and magnitude in the Late Holocene increased the fire occurrence and severity in both sites. During times of little human influence, those fires had little effect on peatland vegetation composition. The coincidence of more frequent fires, a nutrient enrichment and an increased carbon accumulation rate in the Late Holocene suggest that ash-fertilization might have also played a role in the recent past. Thus, low-severity fires could potentially enhance the peatlands' capacity to accumulate carbon if the water table is sufficiently high. • Late Holocene ENSO intensification increased fire occurrences in tropical peatlands. • Prior to past few centuries, human impacts in tropical peatland were little to none. • Those fires caused negligible change on peatland vegetation composition. • Those fires coincided with nutrient enrichment in peatlands in Jambi. • Low-severity fires could play role in enhancing carbon accumulation in peatlands. [ABSTRACT FROM AUTHOR]

In optical transmission systems using the VSB-AM method, there is the problem of noise generation caused by interference between the main signal and reflections from fiber-end connectors or reflections caused by Rayleigh scattering inside the fiber. To date, fiber transmission noise has been investigated in transmission systems with many channels (more than 40). In such large channel transmission systems, it is possible to approximate the fiber noise spectrum by a Gaussian distribution and it can be taken to remain constant inside the transmission bandwidth. However, in master antenna television systems used as counter-measures against obstacles in wave propagation or upstream lines, etc., the number of transmission channels is a maximum of 10, and such approximation is not possible. In this paper, fiber transmission noise is investigated theoretically and experimentally when the number of transmission channels is small. It is found that in a transmission bandwidth of 90–300 MHz, the fiber noise level increases as the carrier frequency is increased; its difference from that in the low frequency region is approximately 5–6 dB. © 1997 Scripta Technica, Inc. Electron Comm Jpn Pt 1, 80 (5): 58–66, 1996 [ABSTRACT FROM AUTHOR]

In this study, the reaction mechanism and activity of acetylene hydrochlorination catalyzed by non-metallic catalysts with different CN ratios were systematically studied using the B3LYP/6-311+G** level of density functional theory (DFT). DFT-D3 density functional dispersion correction was used in the calculation. In this reaction, C 2 N, C 3 N and C 4 N catalysts first adsorbed HCl and then C 2 H 2 , whereas the C 5 N catalyst first adsorbed C 2 H 2 and then adsorbed HCl to form a co-adsorbed structure. The calculation results showed that the reaction energy barrier of different CN catalysts was C 4 N > C 2 N > C 5 N > C 3 N. The energy barrier of the C 3 N catalyst was only 14.87 kcal/mol, which was a potential non-metal catalyst for acetylene hydrochlorination. [ABSTRACT FROM AUTHOR]

This study was conducted to elucidate how changes in critical soil quality characteristics relate to continuous rice cultivation and changes in cropping systems and fertilization in South China over the time span 1980 to 2017. Soil pH, soil organic matter (SOM), total nitrogen (TN), available phosphorus (AP) and potassium (AK) were determined for the samples taken in 2017 and compared to results from the paired samples collected in 1980 by grouping all samples into four cropping systems: continuous paddy fields, new paddy fields developed from uplands, continuous uplands, and new uplands developed from paddy soils. The results show a significant increase in soil pH, AP and AK in all cropping systems, which was, however, coupled with low fertilizer use efficiency. Additionally, a significant increase in SOM came with new paddy soils, whereas a little SOM accumulation and a significantly weakened correlation of TN to SOM occurred in continuous paddy soils. Both low fertilizer use efficiency and deteriorated soil C sequestration function imply a sub-health status of continuous paddy soils. The changes in cropping systems and fertilization, which essentially resulted from expeditious economic growth, should be responsible for the dynamics of C and N and the consequences to soil quality. More experimental studies on balanced fertilization vs. local commonly used fertilization are suggested to probe the mechanisms underlying the C and N dynamics in paddy soils. [ABSTRACT FROM AUTHOR]

To explore the question how litter and macrofauna feces respond to temperature and how respiration differs for litter with a different CN ratio, we compared the decomposition rates of leaf litter (Alnus glutinosa, Salix caprea, and Acer campestre) and isopod (Armadillidium vulgare) feces produced from the same litter in response to three constant (8, 16, and 24 °C) and one fluctuating (first week 8 °C, the other week 24 °C) temperatures in a 50 week laboratory experiment and in a field trial. Microbial respiration of litter with lower CN ratio (alder and willow) was significantly higher than respiration of feces, no significant difference was found for maple litter with higher CN ratio. This was supported by field litter bag experiments where alder and willow litter decomposed faster than feces but the opposite was true for maple litter. Litter respiration was significantly affected by temperature but feces respiration was not. Fluctuating temperature caused either lower or equal respiration as compared to mean constant temperature. The content of phenolics was significantly higher in intact litter in comparison with decomposed litter and feces, either fresh or decomposed. The CN ratio decreased as litter turned to feces in maple and alder litter but increased in willow litter. In conclusion, microbial respiration of both litter and feces were substantially affected by litter quality; the litter was more sensitive to temperature than feces. [ABSTRACT FROM AUTHOR]