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1.
Abstract The use of the LECO CHN‐600 Elemental Analyzer (based on a dry combustion method) for the analysis of soils for their content of organic and total carbon, hydrogen, and nitrogen is described. Organic carbon determined by this means was closely related to organic carbon determined according to the Tyurin method, and total carbon related to organic matter content determined by the loss‐on‐ignition of soil samples. Precision for the carbon and hydrogen determination were acceptable. It was lower in the case of the total nitrogen determination. The time of analysis was approximately 4 to 5 minutes. 相似文献
2.
Abstract Many methods have been proposed to determine the total amount of organic carbon in soil; some of them determine only a percentage of the actual carbon content and therefore the results need the application of a correction factor. Methods for the determination of organic carbon in soil have been rarely extended to organic fertilizers and amendments. We propose a rapid method based on a modification of the original Springer and Klee 10procedure. Samples are oxidized for exactly 10 minutes with a mixture of 20 ml 2N K 2Cr 2O 7and 26 ml conc. H 2SO 4at 160±2°C; the excess dichromate is titrated either potentiometrically or manually with FeSO 4. The method is fast, accurate, and more reliable than other commonly used procedures. The procedure can be easily adopted for serial determination of carbon in both soils and organic fertilizers or amendments 相似文献
3.
Abstract We compared three methods of estimating soil organic carbon (dichromate oxidation with and without external heating and loss‐on‐ignition) with a method for total carbon measured in an automated resistance furnace. In 38 surface (0–150 mm) podzolized sands the concentration of total carbon ranged from 0.39 to 4.57% and was highly correlated with all three methods (r 2=0.99, p<0.0001, in each case). Dichromate oxidation with and without external heating recovered 99.1 and 88.8% of total carbon respectively, indicating that all carbon was organically bound, and that the ‘heat of reaction’ was not sufficient for total oxidation of organic carbon. Because the organic carbon content of the organic matter varied from 38% to 55% a mean value of 46% would be more appropriate for these soils than the Van Bemmelen factor of 58% for converting organic matter to organic carbon concentration The loss‐on‐ignition procedure represents a precise technique for the estimation of organic matter and, when calibrated, organic carbon in surface sandy soils. 相似文献
4.
Abstract Soil organic matter is an active component of agroecosystems. Rapid and precise measurement of organic carbon (C org) is essential to monitor changes in organic matter and soil quality. A new semi‐micro wet digestion method for the determination of C org was developed using rapid microwave energy applied at 500 J mL ‐1 digestion mixture to enhance oxidation of C org by K 2Cr 2O 7and conc. H 2SO 4. This proposed method and three existing methods of soil C determination were compared with the LECO dry combustion carbon analyzer. The r 2 value for the proposed microwave method regressed against LECO C was 0.9913. The recovery of C org by the rapid microwave digestion method for spectrophotometric measurement was 91.7±1.2% (conversion factor 1.09) of C measured by the LECO dry combustion method. Compared to the traditional Walkley‐Black's method, the proposed spectrophotometric with microwave digestion method was rapid and more precise, used smaller reagent volumes, and produced less waste. 相似文献
5.
PurposeThe objectives of this study were to evaluate the effects of long-term organic materials incorporation on the soil aggregate and density-based fractions, and associated soil carbon (C) and nitrogen (N) conversion in the rice fields. Materials and methodsA long-term located experiment was conducted to study the effects of continuous application of organic materials (milk vetch, rice straw, and poultry manure) on the distribution characteristics of soil aggregate and density-based fraction, as well as its organic C and N, in rice fields. The soil aggregate was classified using the wet-sieving method. Light fraction (LF) and heavy fraction (HF) were classified according to density fractionation. Aggregate organic C (AC) and total N (AN), LF organic C (LFC) and N (LFN), and HF organic C and N concentrations were measured by using the Elementar Vario ISOTOPE elemental analyzer. Results and discussionApplication of organic materials increased the aggregate mass proportion of 2–0.25 mm (by 4.9–12.6%) and 0.25–0.053 mm (by 27.5–40.7%) fraction and its AC and AN concentration. The soil aggregate particulate organic C and total N were greatly improved with organic materials application. Furthermore, organic material had more obvious effect on the soil C and N in the LF than HF, which improved the LF particulate mass proportions by 75.1–177.0%, LFC by 51.7–68.4%, and LFN by 14.2–111.2%, respectively. Poultry manure had the greatest effect on increasing the AC, LFC, AN, and LFN, followed by milk vetch and rice straw. ConclusionsMilk vetch, rice straw, and poultry manure could effectively increase the soil intermediate aggregate and LF proportion, and stimulate the stabilization and fixation of C and N in rice fields. It is an effective agricultural practice by applying organic material to improve soil fertility and sustaining high crop productivity. The increases of intermediate aggregate and associated C and N may be the main factor for soil C and N sequestration under continual application of organic materials. 相似文献
6.
Abstract. England and Wales have 155 314 1 × 1 km squares, of which 140049 have more than 50% soil cover. The total soil organic carbon content, based on the dominant soil series and dominant land cover type, is estimated to be 2773 × 10 6 t C. Scotland has 84929 1 × 1 km squares, of which 82 420 have a nominated dominant soil series. The total soil organic carbon content is estimated to be 19011 × 10 6 t C, 6.85 times the total organic carbon content of the soil of England and Wales. The total organic carbon content of the soil of Great Britain is estimated to be 21 784 × 10 6 t C, of which 87% is in Scottish soils and 75% is in Scottish peats. A map of the mean soil organic carbon content of 10 × 10 km squares of the National Grid using classes of equal range illustrates the narrow range of organic carbon contents of the soils of England and Wales and the dominance of organic carbon in Scottish soils. A map using the same data, but with classes of unequal ranges increasing in size with increasing carbon content, is better for showing detailed differences within England and Wales. 相似文献
7.
Abstract Organic carbon (OC) in leaves of seven nitrogen (N 2)‐fixing trees and fifteen lignite‐based fertilizers was measured by loss‐on‐ignition (LOI at 500°C), wet oxidation by the Walkley‐Black method (CWB), Tinsley Dichromate Method (CTS), and dry combustion method using a LECO SC444 Carbon/ Sulphur Resistance Furnace Analyzer (CTO). There were significant differences in the capabilities of the methods in measuring OC from the organic materials with the quantity measured in the following order: LOI > CTO > CTS > CWB. A highly significant difference between LOI and CTO values suggested that components other than organic carbon (C) were removed by LOI since CTO gives total C value. The result also showed that N content in the organic materials was highly correlated with OC measured by individual methods. The LOI, CWB, and CTS were significantly correlated with CTO. The regression equations which were specific for either plant leaves or lignite‐based fertilizers indicated that any of the methods could be used to predict total C in the organic materials with a high degree of precision. In addition to the regression approach, an estimated correction factor of 1.4550 would be more appropriate to predict CTO from CWB for plant leaves than the 1.30 factor usually used for estimating oxidizable C in soils when CWB method is used. Also, a factor of 0.36180 could be used to estimate total C from LOI method for lignite fertilizers instead of merely regarding the difference in weight loss as the total organic matter. 相似文献
8.
PurposeIn this study, 1-year decomposition experiments were conducted to measure the litter carbon decomposition dynamics in saltmarsh and to determine the changes in the chemical structure of litter carbon during the litter decomposition process. MethodsLitterbags containing a mixture of Spartina alterniflora litter and burned sediment were buried at four S. alterniflora saltmarshes and one S. alterniflora–Suaeda salsa co-existing saltmarsh. The contents of total organic carbon (TOC) and recalcitrant carbon (RC) were determined by a Sercon Integra CN isotope ratio mass spectrometer, while the content of labile carbon (LC) was estimated by calculation. 13C nuclear magnetic resonance (NMR) spectroscopy was conducted to characterise the chemical structures of the organic carbon compounds in the S. alterniflora litter during decomposition. Solid-state 13C–CPMAS-NMR spectra were obtained using an AVANCE III 400 MHz (Bruker) spectrometer. ResultsThe results indicated that more RC than LC remained in the litterbag during decomposition. The organic carbon content of the S. alterniflora litter was largely composed of alcoxyl-C compounds (78.9%), the decomposition products of which dominated the litter organic carbon fractions, including the TOC, RC, and LC. In contrast, alkyl-C, aromatic-C, and carboxyl-C products contributed mostly to RC. Differences in the negative correlations between the litter carbon fractions and alkyl-C, aromatic-C, and carboxyl-C were found among the developing saltmarshes. Humus generated by the S. alterniflora litter was mainly composed of macromolecular organic compounds containing functional groups such as methyl, methylene, methine, methoxyl, aromatic rings, phenolic hydroxyl, and carboxyl. ConclusionsDuring decomposition, the organic carbon in the S. alterniflora litter was found to be dominated by O-alkyl-C, followed by aromatic-C, alkyl-C, and carboxyl-C. O-alkyl-C plays a major role in the LC proportion of organic carbon, while aromatic-C, alkyl-C, and carboxyl-C contribute more to the RC proportion. Alkyl-C was found to be more easily decomposed than aromatic-C in the S. alterniflora litter. During litter decomposition, the molecular structure complexity, humification degree, and decomposition degree of organic carbon exhibited seasonal variations. In the 3-year saltmarsh, more decomposition of the organic carbon in the S. alterniflora litter was observed as compared to other sites. 相似文献
9.
PurposeSimilar to fresh- and brackish water aquaculture ponds, commercial shrimp farming in degraded saline areas holds the potential to bury carbon (C) in the sediments. However, studies on the mechanisms of sediment C dynamics and C-flux in response to inland saline aquaculture management practices are still scarce. Therefore, the objectives of the present study are to quantify the C burial rate in inland saline aquaculture ponds and assess the impact of inland saline aquaculture on sensitive C fractions in the bottom sediment of the ponds. Materials and methodsThe sediment samples (n?=?12 from each pond) were collected from six shrimp farming ponds (1000 m2 area of each pond) of different ages. The sediment depth, sediment accumulation rate and the levels of total carbon (TC), total organic carbon (TOC) and sediment oxidizable organic carbon (SOC) and its different fractions were determined using standard procedures. The data were analysed by one-way analysis of variance (ANOVA), followed by the Duncan's multiple range test for comparing the means, and the Pearson correlation test was used to assess the relationship between the different pond sediment parameters and SOC content. Results and discussionThe results revealed that the annual C accumulation rates varied from 902 to 1346 kg C ha?1 year?1 in 7-year-old earthen ponds (EPs) and bottom cemented ponds (BCPs), respectively. The sediment C fractions, including TC, TOC, SOC and its fractions (very labile, VLc; labile, Lc; less labile, LLc), and non-labile carbon (NLc)) were progressively increased over the pond age. The inland saline aquaculture practices over the years increased both active (AC) and passive carbon (PC) pools in the pond sediments, helped in the restoration and improvement of sediment quality and enhanced C sequestration potential of the sediments. Furthermore, a significant increase in the level of particulate organic carbon (POC) in BCPs justified that the non-ploughing practices at BCPs facilitated the formation of macro- and micro-aggregates, thereby increasing the C retention and stability of the pond sediments. ConclusionThis study suggested that the shrimp farming ponds in semi-arid saline soils represented considerable C burial hotspots, enhanced the stable passive C pools and improved the sediment quality. 相似文献
10.
Abstract Total organic carbon content and its composition have been evaluated in the topsoil in the selected plots of 13 long-term field experiments conducted in different soil and climate conditions. The altitude of the sites ranged from 225 – 670 m above sea level. Four variants of the organic and mineral fertilization were selected in each experiment: Nil, which did not receive any organic or mineral fertilizers since the beginning of the experiment, mineral fertilized variant NPK, organic fertilized (manured) variant FYM and both organic and mineral fertilized variant FYM + NPK. Total organic carbon (C) content in the topsoil differed as a result of the soil and climate conditions (it ranged from 0.96 – 1.80% C in the Nil variants) and due to the organic and mineral fertilization. The inert and decomposable part of the soil organic C content was calculated and the hot water soluble carbon content was determined. Relationships between the individual SOM fractions have shown a highly significant correlation, except for the decomposable C calculated as a difference to Nil variant. 相似文献
11.
Abstract We estimated the carbon (C) sequestration potential of organic matter application in Japanese arable soils at a country scale by applying the Rothamsted carbon (RothC) model at a 1-km resolution. After establishing the baseline soil organic carbon (SOC) content for 1990, a 25-year simulation was run for four management scenarios: A (minimum organic matter application), B (farmyard manure application), C (double cropping for paddy fields) and D (both B and C). The total SOC decreased during the simulation in all four scenarios because the C input in all four scenarios was lower than that required to maintain the baseline 1990 SOC level. Scenario A resulted in the greatest depletion, reflecting the effects of increased organic matter application in the other scenarios. The 25-year difference in SOC accumulation between scenario A and scenarios B, C and D was 32.3, 11.1 and 43.4?Mt?C, respectively. The annual SOC accumulation per unit area was similar to a previous estimate, and the 25-year averages were 0.30, 0.10 and 0.41?t?C?ha ?1?year ?1 for scenarios B, C and D, respectively. The system we developed in the present study, that is, linking the RothC model and soil spatial data, can be useful for estimating the potential C sequestration resulting from an increase in organic matter input to Japanese arable soils, although more feasible scenarios need to be developed to enable more realistic estimation. 相似文献
12.
Abstract A simple procedure is described for the rapid determination of organic carbon content in a large number of soil samples using an automated segmented flow analyser. The method is a modification of the wet oxidation/ digestion methods based on potassium dichromate combined with a colorimetric method for determination of chromic oxide (Stevenson and Clare, 1962). Using a segmented flow analyser for the colorimetry, the procedure is capable of automated routine analyses of large numbers of samples and was shown to give high and repeatable recoveries of organic carbon from a range of compounds. Organic carbon values for a range of soils analysed by the reported method and by the dry combustion technique showed a high correlation. 相似文献
13.
Abstract A simple method for routine determination of organic carbon in soil by a modified Mebius procedure is described. It involves (a) digestion of the soil sample with an acidified dichromate (K 2Cr 2O 7‐H 2SO 4) solution for 30 minutes in a Pyrex digestion tube in a 40‐tube block digester preheated to 170°C and (b) estimation of the unreacted dichromate by titration of the cooled digest with an acidified solution of ferrous ammonium sulfate with use of N‐phenylanthranilic acid as an indicator. The method is more rapid and precise than the Mebius procedure commonly used for routine analysis of soils for organic carbon, and the only equipment required for its use is equipment now commonly used for routine Kjeldahl analysis of soils for total nitrogen. 相似文献
14.
Soil organic carbon and nitrogen are key elements of sustainable agriculture. Converting forest land and grassland to arable land is known to decrease the content of soil organic carbon (SOC), whereas converting land under annual crops into perennial grasslands has the potential to increase organic C and N sequestration, an assumption tested in this study. Compared to the levels in reed meadows, SOC and total nitrogen (TN) stocks in the top layer of 2489 Mg soil ha −1 (about 0–15 cm depth) significantly increased 3 years after the conversion, despite a slight decrease numerically in the first year following the conversion. And the mass of light fraction organic carbon (LFOC), total extractable carbon (TEC), humic acid carbon (HAC), and fulvic acid carbon (FAC) stocks all decreased significantly in the first year in the top layer but recovered after 3 years. In the deeper layer of 2549 Mg soil ha −1 (about 15–30 cm depth), however, the levels of SOC and heavy fraction organic carbon (HFOC) stocks began increasing from the first year itself. During the period of 1–10 years after the conversion, the degree of humification rate (HR) for the deeper layer were consistent, averaging 30%, whereas the same parameters in the top layer stabilized after 3 years at 33%. After 10 years of conversion, the soil recorded higher levels of SOC and TN stocks, used as indicators in this study, than those that had prevailed in the reed meadows, demonstrating the positive combined effects of the conversion on the retention of atmospheric C-CO 2 in the soil. This study suggests that proper management of alfalfa fields can maintain or even improve chemical and physical quality of converted reed meadows soils. 相似文献
15.
PurposeArbuscular mycorrhizal-like fungi (AM-like fungi) are crucial for ecosystem functioning and soil organic matter (SOM) is an indicator of soil quality. However, the spatial distribution of arbuscular mycorrhizal-like fungi, glomalin-related soil protein (GRSP) and SOM in a large scale is still unclear. The objectives of this study were to investigate the spatial distribution of SOM, arbuscular mycorrhizal-like fungi and GRSP, and reveal the potential relationship among them in a large scale across China. Materials and methodsSoil samples (different in vegetation type, climate, and soil variables) were collected from 26 sites in a large scale across China. The soil properties including pH, total carbon (TC), total nitrogen (TN), and SOM were determined. Quantitative PCR amplification of the 18S rRNA gene was conducted to evaluate the abundance of arbuscular mycorrhizal-like fungi. The contents of easily extractable GRSP (EE-GRSP), difficultly extractable GRSP (DE-GRSP), and total GRSP (T-GRSP) were measured. Results and discussionArbuscular mycorrhizal-like fungi abundance was significantly affected by the vegetation type and dramatically correlated with the soil TN and mean annual precipitation (MAP). EE-GRSP and DE-GRSP were more associated with the TC and TN content, respectively. The abundance of arbuscular mycorrhizal-like fungi significantly but weakly correlated with the T-GRSP and EE-GRSP. The SOM content positively correlated with the DE-GRSP and T-GRSP. Those results suggested that the arbuscular mycorrhizal-like fungi are a larger contributor to regulating the content of GRSP, which is an important indicator of the soil organic carbon pool. ConclusionsOur results indicated that arbuscular mycorrhizal-like fungi abundance has a greater contribution to driving the distribution of soil C and N in a large scale by affecting the content of glomalin-related soil protein. 相似文献
16.
Abstract Organic matter in Urbic Anthrosols often contains chemically and biologically inert organic carbon. This material, called black carbon (BC), originates from municipal wastes, coal‐mine deposits and/or fly ash. This black carbon needs to be differentiated from the other soil organic substances because of its very different physical and chemical nature. In this paper, we propose a new method for determining BC, integrated into the humic fractionation procedure. The remaining organic carbon in the soil residue left after lipid extraction, alkaline extraction [0.5 M sodium hydroxide (NaOH)], and further oxidation with 30% hydrogen peroxide (H 2O 2) is defined as inert organic carbon or BC. The common fractions of soil organic matter, such as lipids, fulvic and humic acids, and humins are thus supplemented with a new fraction, BC. According to our results by 13C‐NMRspectroscopy, this fraction consists mainly of polyaromatic hydrocarbons with few functional groups. 相似文献
17.
【目的】 研究不同长期耕作措施对作物根际和非根际土壤碳氮元素含量和土壤酶活性的影响,以及土壤碳氮元素与碳氮转化相关酶之间的相互联系,对认识土壤酶响应土壤碳氮变化的机制和选择合理有效的耕作技术具有重要的理论和实践意义。 【方法】 长期耕作试验始于1999年,位于河南孟津县,属于黄土高原东部边缘,土层深厚 (50—100 m),土壤类型是壤质黄绵土。试验处理有草地 (GL)、传统耕作 (CT)、免耕覆盖 (NT)、深松覆盖 (SM),于2016年采集根际土和非根际土0—20 cm、20—40 cm,分析了土壤总碳、有机碳和总氮含量,以及β-葡萄糖苷酶 (BG)、β-纤维二糖苷酶 (CBH)、β-木糖苷酶 (BXYL)、乙酰氨基葡萄糖苷酶 (NAG) 和亮氨酸氨基肽酶 (LAP) 的活性,并进行了土壤碳氮元素含量与酶活性的相关性分析。 【结果】 1) 与传统耕作相比,免耕和深松显著提高了根际和非根际0—20 cm土壤的总碳、有机碳和总氮含量,显著降低了非根际20—40 cm土壤的总碳、有机碳和总氮含量。草地显著提高了根际土壤总碳、有机碳和总氮含量,显著提高了非根际0—20 cm土壤的有机碳含量,显著降低了非根际土壤的总碳含量和非根际20—40 cm土壤中的有机碳含量。深松显著降低了作物根际和非根际土壤C/N,免耕和草地处理显著降低了作物非根际20—40 cm土壤中的C/N,但草地处理显著提高了作物非根际0—20 cm土壤C/N。2) 与传统耕作相比,草地、免耕和深松显著提高了根际土壤中β-葡萄糖苷酶、β-纤维二糖苷酶、β-木糖苷酶和乙酰氨基葡萄糖苷酶的活性。草地显著提高了根际土壤的亮氨酸氨基肽酶活性,免耕和深松显著降低了根际土壤的亮氨酸氨基肽酶活性。3) 碳氮转化相关酶之间均存在正相关关系 (除β-纤维二糖苷酶与亮氨酸氨基肽酶之间)。碳氮转化相关酶与土壤总碳、总氮和有机碳之间均存在正相关关系 (除亮氨酸氨基肽酶与总碳之间),与C/N之间均存在负相关关系。 【结论】 土壤碳氮转化酶之间存在相互促进的关系,共同参与土壤碳氮的转化。长期保护性耕作 (免耕和深松) 可以有效提高土壤表层的总碳、有机碳和总氮含量,提高根际土壤酶活性,有利于营养元素 (有机质、碳氮元素) 的循环转化和作物的吸收利用,以深松效果最好,免耕次之。 相似文献
18.
ABSTRACT Conversion of grassland to cropland is widely reported to deplete soil organic carbon (SOC) largely due to tillage effects on the decomposition of SOC. However, most studies report on long-term changes in SOC following the conversion and little is known about the changes in the short term. Net ecosystem carbon budget (NECB) measures the difference between total C input (i.e., manure, above- and below-ground plant residues) and C loss through heterotrophic respiration (RH). However, most studies that report temporal SOC do not report other components of the NECB like RH, total C inputs and often do not include the cumulative annualized change of these components. This review evaluated the change in C input, RH, NECB and SOC after conversion of permanent/continuous grassland to cropland within 5 years after the conversion. We also reviewed and compared no-tillage and conventional tillage on SOC storage and accumulation. Total C input was higher in grassland than cropland largely due to high root biomass, as opposed to aboveground residue, and therefore grassland tended to have higher NECB. Despite higher NECB in grassland, the SOC stocks in cropland (cornfield) converted from grassland were greater than that in continuous grassland within first 2–3 years of conversion. The combination of manure C addition and tillage in cropland showed potential to maintain NECB and increase SOC. Within the continuous grassland C addition alone increased NECB but did not result in a corresponding increase in SOC. Residue retention and manure addition are recognized as good practices for increasing SOC, this study however, shows that combining them with occasional tillage, especially in managed grasslands, could increase the rate of SOC storage in soils. 相似文献
19.
Abstract The content of soil organic carbon (SOC) and total nitrogen (N tot) was studied in a long-term field experiment with a three-field crop rotation (potato – spring wheat – spring barley) set up on arable sandy loam Stagnic Albeluvisol at Eerika, Tartu, Estonia. The studied factors were: (A) organic fertilizers with three treatments: (i) without organic fertilizer, (ii) farmyard manure (60 t ha ?1) used in every third year, and (iii) different organic (alternative) fertilizers (beet leaves + straw; pure beet leaves; slurry + straw; cereal straw) and (B) mineral nitrogen fertilizer with the rates: N-0; N-40; N-80; N-120 and N-160 kg ha ?1. The study years were 1993, 1996 and 1999. The average content of SOC (1.03%) was significantly influenced by the use of organic fertilizers. Only N tot (mean value 0.110%) was influenced also by fertilization with mineral nitrogen. The C/N ratio (mean value 9.5) reflected changes in the content of SOC and N tot 相似文献
20.
Intensive vegetable production in greenhouses has rapidly expanded in China since the 1990s and increased to 1.3 million ha of farmland by 2016, which is the highest in the world. We conducted an 11‐year greenhouse vegetable production experiment from 2002 to 2013 to observe soil organic carbon (SOC) dynamics under three management systems, i.e., conventional (CON), integrated (ING), and intensive organic (ORG) farming. Soil samples (0–20 and 20–40 cm depth) were collected in 2002 and 2013 and separated into four particle‐size fractions, i.e., coarse sand (> 250 µm), fine sand (250–53 µm), silt (53–2 µm), and clay (< 2 µm). The SOC contents and δ 13C values of the whole soil and the four particle‐size fractions were analyzed. After 11 years of vegetable farming, ORG and ING significantly increased SOC stocks (0–20 cm) by 4008 ± 36.6 and 2880 ± 365 kg C ha ?1 y ?1, respectively, 8.1‐ and 5.8‐times that of CON (494 ± 42.6 kg C ha ?1 y ?1). The SOC stock increase in ORG at 20–40 cm depth was 245 ± 66.4 kg C ha ?1 y ?1, significantly higher than in ING (66 ± 13.4 kg C ha ?1 y ?1) and CON (109 ± 44.8 kg C ha ?1 y ?1). Analyses of 13C revealed a significant increase in newly produced SOC in both soil layers in ORG. However, the carbon conversion efficiency (CE: increased organic carbon in soil divided by organic carbon input) was lower in ORG (14.4%–21.7%) than in ING (18.2%–27.4%). Among the four particle‐sizes in the 0–20 cm layer, the silt fraction exhibited the largest proportion of increase in SOC content (57.8% and 55.4% of the SOC increase in ORG and ING, respectively). A similar trend was detected in the 20–40 cm soil layer. Over all, intensive organic (ORG) vegetable production increases soil organic carbon but with a lower carbon conversion efficiency than integrated (ING) management. 相似文献
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