Reports regarding the effects of long-term organic and inorganic fertilization on the quantity and quality of soil organic carbon (SOC), particularly in Vertisols, are scarce. In this study, we ...combined SOC physical fractionation with
C NMR spectroscopy technology to investigate the effect of 34 years of continuous fertilization on the SOC physical fractions and its chemical composition of 0-20 cm soil layer in a Vertisol. This study consisted of six treatments: no fertilization (control), chemical nitrogen, phosphorus and potassium fertilizers (NPK), low and high amounts of straw with chemical fertilizers (NPKLS and NPKHS), and pig or cattle manure with chemical fertilizers (NPKPM and NPKCM). Over 34 years of continuous fertilization, the SOC sequestration rate was from 0.08 Mg C ha
yr
in the control treatment to 0.66 Mg C ha
yr
in the NPKCM treatment, which was linearly related with the C input (P < 0.01). Of the five SOC physical fractions, two silt plus clay fractions (S + C_M, S + C_mM) dominated 74-92% of SOC, while three POM fractions (cPOM fPOM and iPOM) were only 8-26%. The two manure application treatments significantly increased all the SOC physical fractions except for the silt plus clay fraction within macroaggregates (S + C_M) compared with NPK treatment (P < 0.05), which was dependent on the larger amount of C input. Also, the two manure application treatments increased the levels of alkyl C and aromatic C but decreased O-alkyl C (P < 0.05), whereas the straw application (NPKLS and NPKHS) had no impact on the C functional groups (P > 0.05). Overall, the combination of animal manure with inorganic fertilization could enhance the SOC sequestration and alter its quantity and quality in Vertisols.
The India-Asia collision processes are under current debate, mainly due to the large variations of the pre-collision position of the southern margin of Asia, in the range of 10–30°N. To resolve this ...uncertainty, we report new paleomagnetic data of the Xigaze forearc basin sediments from the Zhongba Cuojiangding area. Characteristic remanent magnetizations (ChRMs) were obtained from the upper Cretaceous Qubeiya Formation (Fm) and the early Eocene Jialazi Fm. Both mean directions passed the fold test and also passed the reversal test. An elongation-inclination analysis for all the Jialazi Fm ChRM directions yielded an unflattened mean inclination of 41.6°, with 95% confidence limits between 36.0° and 49.0° (f = 0.76), consistent with the Qubeiya Fm results. The overall mean direction for the Qubeiya Fm is D = 334.8°, I = 42.7°, k = 11.8, α95 = 6.7°, n = 42 in stratigraphic coordinates, corresponding to a paleolatitude of 24.8°N and a paleopole at 67.1°N, 347.5°E with A95 = 7.1°. The tilt-corrected mean direction, combined with published data, for the Jialazi Fm is D = 340.5°, I = 41.6°, k = 8.7, α95 = 5.2°, n = 87, corresponding to a paleolatitude of 23.9°N and a paleopole at 71.6°N, 340.0°E with A95 = 5.0°. Our updated results indicate a paleolatitude of ~24°N for the Xigaze forearc basin during 70–50 Ma, suggesting that a significant Greater Asia is very unlikely, and strongly supporting a two-stage model for the India-Asia collision with a ~ 55 Ma initial collision of India with an equatorial intra-oceanic arc in the northern hemisphere low latitude followed by the collision between India-plus-arc and Asia in late Eocene.
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•The Xigaze forearc basin was located at ~24°N during 70–50 Ma.•The Asian crustal shortenings are 600 ± 800 km (70 Ma) and 700 ± 600 km (50 Ma).•Our new data strongly support a ~ 55 Ma intra-oceanic arc-continent collision.
为探究覆盖作物种植对淮北平原砂姜黑土团聚体稳定性和有机碳组分的影响，本研究以淮北平原砂姜黑土为研究对象，研究不压实及压实处理下不同覆盖作物类型（休闲、苜蓿、油菜、萝卜+毛苕子混播）对表层土壤（0~10 cm和10~20 cm）团聚体稳定性及其有机碳组分的影响。结果表明：与休闲相比，种植不同覆盖作物（苜蓿、油菜、萝卜+毛苕子）均能显著提高两种压实处理0~10 ...cm土层有机碳（SOC）含量，其中苜蓿处理增幅最大（14.3%）；在10~20 cm土层，仅苜蓿处理显著增加了SOC含量（9.17%~10.8%）。在0~10 cm和10~20 cm土层，各覆盖作物处理土壤水稳性团聚体平均质量直径（MWD）的变化规律与土壤有机碳完全一致，均表现为苜蓿处理显著提高了两个土层的MWD。与休闲相比，3个种植覆盖作物处理均能显著提高0~10 cm土层水稳性大团聚体（≥2 000 μm）的含量；10~20 cm土层中仅苜蓿处理在两种压实处理下水稳性大团聚体（≥2 000 μm）含量较休闲处理有显著提升。种植覆盖作物使不同粒级团聚体SOC含量均呈现出增加的趋势，其中苜蓿处理显著增加了0~10 cm和10~20 cm土层≥2 000、250~<2 000 μm和53~<250 μm团聚体SOC含量。与休闲处理相比，苜蓿、油菜和萝卜+毛苕子处理均显著增加了0~10 cm和10~20cm土层土壤颗粒有机碳（POC）含量，其中苜蓿处理的增幅均为最大（25.2%~34.5%）。覆盖作物对土壤矿物结合态有机碳（MOC）含量无显著影响。与不压实处理相比，压实处理对SOC、POC和MOC含量以及水稳性团聚体MWD均无显著影响。研究表明，种植覆盖作物尤其是苜蓿可以显著提高砂姜黑土总有机碳和颗粒有机碳含量以及水稳性团聚体的稳定性，从而改善砂姜黑土质量并提升其生产力。This study investigated the effects of cover crops on aggregate stability and organic carbon fractions of the Shajiang black soil in the Huabei Plain. Four cover cropping treatments（fallow, alfalfa, oilseed rape, and radish with hairy vetch mixture）wi
Degraded soil aggregation arising from nitrogen (N) fertilization has been reported in many studies; however, the mechanisms have not yet been clarified. Elucidating the impact of N fertilization on ...soil aggregation would help to improve soil structure and sustain high crop production. The objective of this study was to determine the impact of long-term N fertilization on soil aggregation and its association with binding and dispersing agents. A 12-year (2008–2019) N fertilization field experiment on a Vertisol was performed, covering a wide range of N application rates (0, 360, 450, 540, 630, and 720 kg ha-1 year-1) and including straw management (straw return and straw removal) in a wheat (Triticum aestivum L.)-maize (Zea mays L.) cropping system. Soil samples of 0–20 cm depth were collected from 12 field treatments with 3 replications in 2019. Soil aggregate stability (mean weight diameter (MWD)) and contents of soil organic carbon (SOC), glomalin-related soil protein (GRSP), microbial biomass carbon (MBC), and mineral N (NH4+ and NO3-) were determined. Long-term N fertilization under straw removal conditions reduced soil MWD by 12%–18% at N rates from 0 to 720 kg ha-1 compared to that under straw return (P < 0.05). Soil MWD was positively associated with pH (P < 0.05) and MBC (P < 0.05), but negatively correlated with NH4+ (P < 0.05) and NO3- (P < 0.05). Compared with the straw removal treatment, the straw incorporation treatment significantly improved the contents of aggregating agents (SOC, GRSP, and MBC) (P < 0.001), but did not affect that of the dispersing agent (NH4+) (P > 0.05); consequently, it improved soil aggregation. Overall, our results indicate that long-term N fertilization may degrade soil aggregation because of the increases in monovalent ions (H+ and NH4+) and the decrease in MBC during soil acidification, especially when the applied N dose exceeded 360 kg ha-1 year-1. Our finding can minimize the negative structural impacts on Vertisol.
Straw return is a promising strategy for managing soil organic carbon (SOC) and improving yield stability. However, the optimal straw return strategy for sustainable crop production in the wheat ...(Triticum aestivum L.)–cotton (Gossypium hirsutum L.) cropping system remains uncertain. The objective of this study was to quantify the long-term (10 years) impact of carbon (C) input on SOC sequestration, soil aggregation and crop yields in a wheat–cotton cropping system in the Yangtze River Valley, China. Five treatments were arranged with a single-factor randomized design as follows: no straw return (Control), return of wheat straw only (Wt), return of cotton straw only (Ct), return of 50% wheat and 50% cotton straw (Wh-Ch) and return of 100% wheat and 100% cotton straw (Wt-Ct). In comparison to the Control, the SOC content increased by 8.4 to 20.2% under straw return. A significant linear positive correlation between SOC sequestration and C input (1.42–7.19 Mg ha−1 yr−1) (P<0.05) was detected. The percentages of aggregates of sizes >2 and 1–2 mm at the 0–20 cm soil depth were also significantly elevated under straw return, with the greatest increase of the aggregate stability in the Wt-Ct treatment (28.1%). The average wheat yields increased by 12.4–36.0% and cotton yields increased by 29.4–73.7%, and significantly linear positive correlations were also detected between C input and the yields of wheat and cotton. The average sustainable yield index (SYI) reached a maximum value of 0.69 when the C input was 7.08 Mg ha−1 yr−1, which was close to the maximum value (SYI of 0.69, C input of 7.19 Mg ha−1 yr–1) in the Wt-Ct treatment. Overall, the return of both wheat and cotton straw was the best strategy for improving SOC sequestration, soil aggregation, yields and their sustainability in the wheat–cotton rotation system.
An increasing number of coking enterprises are challenged by excessive sulfur content in their crude benzene products, which hinders sales and revenue. In this work, microcrystalline adsorbent was ...used to remove carbon disulfide and thiophene in crude benzene. BET, XRD, XRF and SEM characterization showed that the microcrystalline adsorbent has a large specific surface area, high crystallinity morphology, Si/Al ratio and regeneration stability. By investigating the effects of adsorption time, temperature, adsorbent dosage and regeneration times on the desulfurization performance of microcrystalline adsorbent W1, it was found that the desulfurization effect was mainly affected by time and temperature. When the experimental conditions at 20°C, 7 h, the amount of adsorbent was 4.5 g, the volume of crude benzene was 10 mL, resulting in desulfurization rate of 67% for thiophene, 52% for carbon disulfide, and 62% for total desulfurization, approximately 26% for crude benzene loss rate. The overall desulfurization rate remained stable around 55% after three regenerations, while the rate for rude benzene loss increased to roughly 30%. The results indicate that the microcrystalline adsorbent exhibits significant potential for desulfurization of crude benzene, providing valuable guidance and reference for coking enterprises.
More and more coking enterprises are facing the problem of excessive sulfur content in coking light benzene products. However, due to the complexity of coking production process and the unknown ...influencing factors and rules, enterprises often cannot take effective measures. Based on the coking and gas purification process of a typical coking enterprise in China, with the help of specially designed gas sampling and sulfur content detection methods, this paper explores and analyzes the influence of coal, the main sections of gas purification and important liquid substances on sulfur content in light benzene, and puts forward feasible optimization control measures, which can provide useful reference and guidance for coking enterprises in the same industry.
The leaf economic spectrum (LES) has been repeatedly verified with regional and global datasets. However, the LES of desert plants and its drivers has not been fully explored at the species level. In ...this study, we sampled three desert perennial plant species (
,
, and
) at three different geographical areas of distribution in Xinjiang, China, and measured 10 leaf economic traits to determine their strategy of resource utilization. The scores of the first axis from the principal component analysis of 10 leaf economic traits as a continuous variable define the LES. This study showed that the LES did exist in desert plants in this region. The leaf economic spectrum shifted from a more conservative strategy to a more acquisitive strategy with increasing contents of soil potassium (K) and the ratio of K to phosphorus. Except for the vein density of
which quadratically correlated with LES, the vein density, distance between veins, and vein loopiness significantly positively correlated with the LES (
< 0.05), indicating a covariation and tradeoff relationship. The annual mean temperature was significantly negatively correlated with LES, while the annual mean precipitation (MAP) and the aridity index (AI), which was calculated by the ratio of MAP to potential evapotranspiration, significantly positively correlated with the LES. Of these, vein loopiness and AI were more effective at predicting the change in LES from anatomical and climatic perspectives owing to their high regression coefficients (R
). The findings of this study will substantially improve the understanding of the strategies of desert plants to utilize resources and predict the structure and function of ecosystems.
The combustion behaviors of semi-coke, anthracite, bituminous coal and their blends were studied using a thermogravimetric analyzer. Compared with anthracite, the experiments showed that semi-coke ...had low ignition temperature, good comprehensive combustion characteristics and high burnout rate. In compound samples, with the increase of SC1 semi-coke content, the ignition temperature of BC bituminous coal, IC mixed sample and SC1 compound samples gradually decreased, and the comprehensive combustion characteristic index S increased, and the TG curves of the compound samples moved to the low temperature. In the BC and IC compound sample, the ignition temperature and comprehensive combustion characteristic index of compound samples also improved with the addition of SC2 semi-coke and SC3 semi-coke. Furthermore, By means of the universal integral method, the results indicated that the shrinkage cylinder model of phase boundary reaction was the most probable mechanism function of semi-coke, anthracite and bituminous coal combustion. The kinetic parameters of the samples are obtained that the activation energy of semi-coke was lower than that of anthracite. In summary, mixing semi-coke with pulverized coal into blast furnace was beneficial to fuel combustion.
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