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1.
Carbon fluxes in sodic and saline soils were investigated by measuring the soil microbial biomass (SMB) and soil respiration rates under controlled conditions over 12 weeks. Gypsum (10 t/ha) and organic material, as kangaroo grass (10 t/ha), were incorporated in an acidic and an alkaline saline–sodic soils. Cumulative soil respiration rates were lowest in the sodic and saline soils without amendment, while the highest rates were found in those soils that had organic material addition. The addition of gypsum decreased the cumulative respiration rates in the 0–5 cm layer compared to the addition of organic material and the addition of organic material and gypsum. Similarly, the SMB was lowest in the sodic and saline soils without amendment and highest in the soils which had organic material addition, while the effects of gypsum addition were not significant. The low levels of respiration and SMB were attributed to the low soil organic carbon (SOC) levels that result from little or no C input into the soils of these highly degraded landscapes as the high salinity and high sodicity levels have resulted in scarcity or absence of vegetation. Following the addition of organic material to the sodic and saline soils, SMB levels and respiration rates increased despite adverse soil environmental conditions. This suggests that a dormant population of salt-tolerant SMB is present in these soils, which has become adapted to such environmental conditions over time and multiplies rapidly when substrate is available.  相似文献   

2.
ABSTRACT

Attempts were made to ameliorate sodic black calcareous soils by using different crop residues (composted cotton stalk and biomulch 5 t ha?1, respectively) and green manures (in-situ Crotalaria juncea, Sesbania aculeata, Vigna unguiculata, Vigna radiata, and ex-situ Leucaena leucocephala loppings 5 t ha?1) and gypsum 2.5 t ha?1. The organic amendments were outperformed with respect to improvement in soil microbial biomass carbon and dehydrogenase activity, not gypsum. The application of dhaincha significantly improved the mean weight diameter by 14% over control. The application of gypsum and dhaincha recorded a significant drop in pHs (0.1 and 0.07 units) and exchangeable sodium percentage (26.7% and 20.6%) over control. After 2 years of experiments, dhaincha (14.8%) and sunhemp (15.5%) also showed the commensurable potential of improving yields of chickpea as compared to gypsum (14.8%) over control. Hence, dhaincha and sunhemp can be a better alternative choice to gypsum in sodic soils.  相似文献   

3.
An experiment was performed to examine the chemical and biological effects on high clay sodic subsoil following the incorporation and incubation with organic amendments. The main treatments consisted of amendments with wheat shoots, lucerne pellets and peat, and these were compared to gypsum addition. Additional treatments were residues of chickpea and canola, chicken manure and sawdust. All materials were finely ground and added to crushed and sieved soil at the rate of 1% by weight. Wheat, canola and chickpea residues and chicken manure resulted in modest reductions in soil sodicity. Carbon and N mineralization were related to the soluble C/total N ratio in the amendment. The initial mineralization of wheat amendment was rapid due to its soluble C content, but then slowed to have the lowest loss, of around one third of added C, of all the plant residues after 174 days. In comparison, lucerne-amended soil increased total N and lost almost half of its C after the 174-day incubation. The canola stubble amendment showed the highest carbon loss, losing 64% of its added C. The addition of gypsum resulted in high soil electrical conductivity which suppressed respiration, compared to the control soil, indicating a detrimental effect on microbial activity due to the high electrolyte concentration in the soil. The peat amendment, with a low-soluble C content, showed a similar respiration rate to the control soil, confirming that a source of soluble C is important for the initiation of rapid biological activity. Soil pH was significantly increased (by 0.6 of a pH unit) with addition of chicken manure, and still remained higher than control soil after 174 days of incubation. Lucerne was the only plant residue to increase soil pH, with the effect being sustained for 56 days. The study demonstrated how some organic amendments can improve chemical fertility and biological activity in high clay sodic subsoil, and at the same time contribute, after 25 weeks incubation, to an increase in carbon content.  相似文献   

4.
Abstract

Influence of long‐term sodic‐water (SW) irrigation with or without gypsum and organic amendments [green manure (GM), farmyard manure (FYM), and rice straw (RS)] on soil properties and nitrogen (N) mineralization kinetics was studied after 12 years of rice–wheat cropping in a sandy loam soil in northwest India. Long‐term SW irrigation increased soil pH, exchangeable sodium percentage (ESP), and sodium adsorption ratio (SAR) and decreased organic carbon (OC) and total N content. On the other hand, application of gypsum and organic amendments resulted in significant improvement in all these soil properties. Mineralization of soil N ranged from 54 to 111 mg N kg?1 soil in different treatments. Irrigation with SW depressed N mineralization. In SW‐irrigated plots, two flushes of N mineralization were observed; the first during 0 to 7 d and the second after 28 d. Amending SW irrigated plots with GM and FYM enhanced mineralization of soil N. Gypsum application along with SW irrigation reduced cumulative N mineralization at 56 days in RS‐amended plots but increased it under GM‐treated, FYM‐treated, or unamended plots. Nitrogen mineralization potential (No) ranged from 62 to 543 mg N kg?1 soil. In the first‐order zero‐order model (FOZO), the easily decomposable fraction ranged from 5.4 to 42 mg N kg?1 soil. Compared to the first‐order single compartment model, the FOZO model could better explain the variations in N mineralization in different treatments. Variations in No were influenced more by changes in pH, SAR, and ESP induced by long‐term SW irrigations and amendments rather than by soil OC.  相似文献   

5.
以黄土丘陵区典型草原带宁夏固原地区为例,研究了退耕地在植被自然恢复过程中土壤有机碳密度及微生物量碳的动态变化。结果表明,植被自然恢复过程中,土壤有机碳(SOC)和微生物量碳(SMBC)表现为0-5cm土层5-10cm土层10-20cm土层,且在不同土层之间的差异性达到极显著水平(P0.01)。SOC和SMBC在植被自然恢复过程中亦表现出一定的表聚性。土壤剖面各土层SOC和SMBC皆随植被恢复年限的增加总呈上升趋势,且与恢复年限之间呈极显著的对数函数关系。植被恢复0～23a期间,表层土壤(0-5cm)SOC和SMBC年增长率分别为4.81%和6.96%,增加幅度较大;植被恢复23～75a期间,表层土壤SOC和SMBC的年增长率均为0.25%,增加趋势减缓。土壤剖面各土层微生物熵(SMQ)变化于2.113～4.375。土壤有机碳周转速率在恢复前期(0～12a)较快,恢复后期(12～75a)趋于稳定,土壤有机碳积累与转化主要发生在土壤表层。SOC和SMBC之间有极显著的线性正相关关系。植被恢复0～23a期间,与对照农地相比,0-20cm土层土壤有机碳密度增加了85.23%,增加速率较快;而在植被恢复23～75a期间,有机碳密度仅增加了6.60%,增幅减缓。表明植被自然恢复有助于黄土丘陵区土壤有机碳储量的增加,促进土壤碳固定。  相似文献   

6.
[目的]研究不同追施尿素量对麦后复种油菜生物产量和耕层土壤有机碳、土壤微生物量碳氮及碳库管理指数的影响,为麦后复种油菜尿素施用量提供依据。[方法]在古浪县进行小区试验,设置5个试验水平:追施尿素0,90,120,150,180kg/hm2。[结果]追肥可提高麦后复种油菜的生物产量;土壤有机碳、微生物量碳、微生物氮以及碳库管理指数均随追肥量的增加呈抛物线型变化的趋势;碳库指数和碳库管理指数的变化趋势同有机碳的变化趋势;有机碳、微生物量碳与碳库管理指数显著相关,有机碳与碳库管理指数极显著相关,微生物量碳与有机碳含量虽呈现正相关关系,但未达到显著相关性。[结论]综合油菜生物产量和土壤微生物量等指标,古浪县麦后复种油菜的施肥量以追施尿素120~150kg/hm2为宜。  相似文献   

7.
Excessive sodium content in sodic soils is an important limiting factor for cultivation of agricultural crops. The present study was conducted to explore the influence of a novel organic amendment (SFOA) along with use of plant-growth-promoting fungi (PGPF) on soil properties and growth/yield of Oryza sativa L. The combined application of PGPF and SFOA increased total organic carbon (TOC) (0.62%) and decreased the exchangeable sodium percentage (ESP) (15.6%) of soil more significantly from 0.56% (TOC) and 30.1% (ESP), respectively compared to SFOA alone treatment. The combined application reduced soil bulk density, pH, and electrical conductivity (EC) and improved soil enzymatic activities. A significant negative correlation was observed between grain yield with soil ESP and bulk density (r = –0.728, and –0.789, respectively). This study showed that the combined treatment of PGPF and SFOA could enhance the potential of organic amendments for alleviating salt stress in rice.  相似文献   

8.
Poor soil health and low soil water content during crop growing period are major factor for low productivity of pearl millet – mustard rotation under rainfed semi-arid regions. The authors evaluated five different tillage and residue management practices for improving physico–chemical and biological properties of soil. Results showed that conservation agriculture (CA) practice (zero tillage (ZT) with 4 t ha–1 residue retention) exhibited higher proportion of soil macro-aggregate. It also increased infiltration rate of about 15.2% over conventional tillage without residue but ZT increased soil penetration resistance in surface soil layer. In the residue applied plots, ~2–4% (w/w) higher soil water content was maintained throughout the season than the no-residue plots. CA practice had the highest soil organic carbon (4.96 g kg–1) and microbial biomass carbon (188.3 μg g–1 soil). Significant and positive correlation was also found between soil organic carbon with infiltration rate (r = 0.73**), mean weight diameter (r = 0.80**) and microbial biomass carbon (r = 0.86**). Thus, this study suggests that ZT with residue retention can be advocated in pearl millet – mustard rotations for improving, productivity, soil health and maintaining higher soil water content in rainfed semi-arid regions.  相似文献   

9.
为探讨不同海拔梯度对土壤活性有机碳库的影响,以西藏色季拉山(西坡)的高山灌丛(AS)、杜鹃林(RF)、急尖长苞冷杉林(AGSF1～6)和林芝云杉林(PLLF)为试验对象,研究林地土壤有机碳、微生物量碳和易氧化态碳的变化特征。结果表明:高海拔植被类型具有较高的土壤活性有机碳含量和分配比例。土壤有机碳含量与土壤pH值和容重呈显著负相关(p<0.05)。在土壤剖面垂直分布上,随着土壤深度增加,土壤总有机碳、微生物量碳和易氧化态碳含量均呈现随土层深度增加而逐渐减小的变化规律。土壤总有机碳、微生物量碳和易氧化态碳含量沿海拔梯度具有明显的变化规律,即随海拔的升高,土壤总有机碳、微生物量碳和易氧化态碳含量逐渐变大。土壤微生物量碳和总有机碳量有较好的正相关性,有机碳含量越高,土壤微生物量碳越大。  相似文献   

10.
Soil organic carbon (SOC) turnover is the most ubiquitous and ecologically fundamental process in soils. It is generally assumed that SOC is utilised by functionally redundant soil-specific microbial communities which do not differ in their capability to mineralise soil organic matter. To challenge this assumption, incubation experiments were conducted to analyse the community-specific effects on SOC turnover for six mineral soils under different land-use. Comparisons of respiration by a native soil community and an alien community both inoculated to sterilised soils revealed 29 ± 18% higher respiration by the native community (‘home-field advantage’). Increased soil microbial community diversity, as generated by mixing several microbial inoculants, did not result in increased mineralisation rates. Even under impaired conditions, in the presence of aged engine oil as a less decomposable substance, communities with higher diversity did not show higher respiration rates. Also, in non-sterilised soils, we detected the influence of the microbial community composition on respiration rates: Investigations on the effect of mixing two communities in a 50:50 untreated soil mixture showed declining respiration in three out of six cases (by 23.9 ± 5.9%) and increased respiration in one case (by 57%) compared to the mean respiration of the two unmixed soils. These effects were highly related to the microbial community capability, with only communities with low capability profiting from mixing with a second community. Our results question the assumption of redundancy of microbial community’s functionality for SOC mineralisation in soils.  相似文献   

11.

Purpose  

Although organic amendments have been recommended as one of the practices for crop production and soil carbon sequestration, little has been done to evaluate soil organic carbon (SOC) dynamics following long-term application of organic amendments. The objective of this research were to (1) assess the effect of long-term organic amendments on SOC dynamics in rice-based systems; (2) evaluate the relationship between soil carbon sequestration and carbon input based on various mineral and organic fertilization treatments.  相似文献   

12.
Continuous cultivation has been known to decrease soil organic matter content. Application of organic matter to cultivated soil is an important practice from the point of view of maintaining an adequate amount of soil organic matter. Soil organic matter content significantly affects soil microbial activity, which is an important index of soil quality. In this study, a field experiment was conducted to examine the long-term effects of different kinds of organic matter in combination with inorganic nitrogen (N) fertilizer on chemical and biological properties of soils. There were seven treatments, namely (1) CK (without fertilization), (2) Chem-N (applying chemical N fertilizer only), (3) Comp (applying compost with the same rate of N as the Chem-N treatment), (4) Comp + l/3 N (applying compost complemented with 33% of the chemical N fertilizer of the Chem-N treatment), (5) Comp + 2/3 N (applying compost complemented with 66% of the chemical N fertilizer of the Chem-N treatment), (6) GM + 1/3 N (applying green manure complemented with 33% of the chemical N fertilizer of the Chem-N treatment) and (7) Peat + 1/3 N (applying peat complemented with 33% of the chemical N fertilizer of the Chem-N treatment). After continuous treatment for 12 years and with cultivation of 24 crops on the same area, soils were sampled for analyses of chemical and biological properties, enzymatic activities and phospholipid fatty acid (PLFA) profiles. The results showed that compared with CK and Chem-N treatments, applications of compost and peat increased soil organic carbon (SOC) content and altered microbial activities and microbial community structure. However, application of green manure for 12 years had no effect on SOC content. Both microbial activities and PLFA profiles were clearly dependent on the characteristics of the applied organic amendments. In summary, a peat application led to the highest increase in SOC content compared to compost and green manure; however, compost-treated soil had a higher microbial population and higher microbial and enzyme activities, while the effects of both green manure and chemical N fertilizer on soil properties were similar.  相似文献   

13.
鉴于多种技术被用于控制崇明东滩互花米草的蔓延,为了选择更好的互花米草控制技术,首先比较不同控制技术作用下湿地土壤总有机碳（SOC）含量的差异,并对土壤中的微生物活性进行研究以分析土壤中总有机碳的输出能力,进而分析土壤总有机碳的保留能力。结果表明,经过刈割／翻耕、刈割／翻耕／水位调节、刈割／生物（芦苇）替代等控制措施后,湿地土壤中土壤总有机碳含量、可培养微生物菌落数、土壤转化酶活性和土壤呼吸强度均高于对照,而通过DGGE技术对微生物种群进行分析后发现,修复后的湿地土壤多样性显著低于对照。在几种不同的控制技术中,刈割／翻耕／水位调节模式由于增加了土壤的滞水时间,其土壤微生物活性相对较低,有机碳含量较高,表明采用该修复技术后土壤的碳代谢能力相对较弱,因此该修复技术更有利于湿地土壤有机碳的保留。相对其他控制技术而言,刈割／翻耕／水位调节模式可在控制互花米草蔓延的同时有效地保留土壤有机碳。  相似文献   

14.
喀斯特石漠化过程对土壤活性有机碳的影响   总被引：6，自引：1，他引：6  
以贵州省花江峡谷区典型喀斯特石漠化小流域为研究区域,对潜在、轻度、中度、强度石漠化等级样地代表性土壤活性有机碳进行了测试分析.分析结果表明,随着石漠化程度的增加,土壤微生物生物量碳(sMBc)、轻组有机碳(LFOC)、可矿化碳(MC)、微生物商(qSMBC)呈下降趋势,微生物呼吸商(qCO2)呈上升趋势,与石漠化过程有一致性,能较好体现石漠化过程中土壤退化的本质.开垦序列土壤活性有机碳库的周转速率和土壤微生物碳库的下降速率大于樵采序列,使得开垦序列土壤即使在高的生物归还量下,形成土壤有机碳的比例相对较小.土壤SMBC,LFOC,MC,易氧化有机碳(LOC),qSMBC,qCO2等生物学性质除了与人为干扰方式有关外,还与植被生物量有关,可以体现土壤质量发展的方向,是石漠化过程土壤退化及恢复评价的敏感指标.  相似文献   

15.
Land-use change (LUC) is widely considered a major factor that affects soil organic carbon (SOC) sequestration. The impacts of four LUC types on soil properties, SOC, particulate organic carbon (POC) and labile organic carbon (LOC) at the 0–100 cm depth were examined in the west of Loess Plateau, northwest China. Bulk density at the 20–40 cm depth increased significantly after native grassland conversion to cropland, while artificial grassland establishment and abandonment on former cropland caused reverse change. Soil water content in the profile increased 60–230% after cultivation and decreased 32–49% after abandonment (p < 0.01). The particle size distribution also showed a response to LUC. Only artificial grassland establishment caused an SOC sink of 32% at the 0–10 cm depth as well as two labile fractions. SOC tended to increase after cultivation and after abandonment, with 6% and 20% at soil surface, respectively. There were increasing trends in POC and LOC. After afforestation on former native grassland, SOC tended to decrease (23%) at the 0–10 cm depth while POC and LOC tended to increase (33% and 6%, respectively). Principal component analysis was successful in separating LUC through soil property parameters. Carbon sequestration is largely ascribed to increased below-ground production and tillage elimination after perennial alfalfa (Medicago sativa L.) plantation. Irrigation and fertilization activities contribute to SOC accumulation after cultivation to some extent. The self-restoration dynamic depending on time since abandonment is important to SOC change. A lower proportion of stabilized carbon results in a slow rate of SOC accumulation after afforestation. It is necessary to investigate the long-term dynamic after LUC.  相似文献   

16.

Purpose

Soil organic carbon (SOC) sequestration in croplands plays a critical role in climate change mitigation and food security, whereas the stability and saturation of the sequestered SOC have not been well understood yet, particularly in rice (Oryza sativa L.) fields. The objective of this study was to determine the long-term effect of inorganic fertilization alone or combined with organic amendments on SOC stability in a double rice cropping system, and to characterize the saturation behavior of the total SOC and its fractions in the paddy soil.

Materials and methods

Soils were collected from a long-term field experiment in subtropical China where different fertilization regimes have been carried out for 31 years. The total SOC pool was separated into four fractions, characteristic of different turnover rates through chemical fractionation. Annual organic carbon (C) inputs were also estimated by determining the C content in crop residues and organic amendments.

Results and discussion

Relative to the initial level, long-term double rice cropping without any fertilizer application significantly increased SOC concentration, suggesting that double rice cropping facilitates the storage and accumulation of SOC. The partial substitution of inorganic fertilizers with organic amendments significantly increased total SOC concentration compared to the unfertilized control. Total SOC increased significantly with greater C inputs and did not show any saturation behavior. Increased SOC was primarily stored in the labile fraction with input from organic amendments. However, other less labile SOC fractions showed no further increase with greater C inputs exhibiting C saturation.

Conclusions

While the paddy soil holds a high potential for SOC sequestration, stable C fractions saturate with increasing C inputs, and thus, additional C inputs mainly accumulate in labile soil C pools.  相似文献   

17.
ABSTRACT

Soil organic carbon (SOC) is a key component for sustaining crop production. A field experiment was conducted during 2004–2018 to assess the changes in soil carbon fractions under different fertilization practices in grass-legumes mixture. The result indicates that application of farmyard manure (FYM) at 80 Mg ha–1 has increased SOC concentration leading to carbon sequestration rate of 4.2 Mg ha–1 year–1. Further, it has increased the proportion of labile carbon in the total SOC and have accumulated 126, 60, 83 and 95% higher very labile, labile, less labile and non-labile C stock than that of control plot, respectively, in top 30 cm soil layer. Inorganic fertilization and FYM 20 Mg ha–1 influenced SOC concentration, SOC stock and C sequestration rate similarly. The highest carbon management index (264) was found in the treatment receiving FYM 80 Mg ha–1 and it was positively correlated with SOC (r = 0.84**). The sensitivity index of the SOC varied from 26 to 152% and the differences were greatest in FYM treatments. The result indicates that grass-legumes mixture build-up the SOC in long term and the addition of FYM further increases it.  相似文献   

18.
ABSTRACT

Soil degradation due to salinization and sodication is the paramount threat in Indo-Gangetic plains. The studies on reclamation and management of such soils can provide a pragmatic solution for improving fertility and productivity of these soils. Lack of organic matter and poor availability of nutrients are the major factors for low productivity of sodic soils. Rice-wheat is a major cropping system in Indo-Gangetic alluvial plain region even in reclaimed sodic soils and farmers used inorganic fertilizers only to get higher yields. In this study, we used different organic sources of amendments in conjunction with different nitrogen (N) doses supplied through inorganic fertilizers to investigate the combined effect of organic and inorganic amendments on soil fertility and the productivity of rice- wheat system in sodic soils. Salt tolerant varieties of rice and wheat were grown in sodic soil (pH: 9.30, EC: 1.12 dSm?1 and exchangeable sodium percentage, ESP: 52) during 2014–15 to 2016–17 in a field experiment with 13 treatment combinations of organic and inorganic amendments (T1- (control) 100% of recommended dose of N (RDN), T2-municipal solid waste compost (MSWC) @10 t ha?1 + 50%RDN, T3- MSWC @10 t ha?1 + 75% RDN,T4- MSWC @10 t ha?1 + 100%RDN, T5-Vermicompost (VC) @10 t ha?1 + 50% RDN, T6- VC @10 t ha?1 + 75% RDN, T7-VC@10 t ha?1 + 100% RDN, T8- Farm yard manure (FYM) @ 10 t ha?1 + 50% RDN,T9- FYM@10 t ha?1 + 75%RDN, T10- FYM@10 t ha?1 + 100% RDN, T11-Pressmud (PM) @10 t ha?1 + 50% RDN, T12-PM@10 t ha?1 + 75%RDN, and T13- PM @ 10 t ha?1 + 100% RDN). Use of organic amendments supplemented with reduced dose of N through inorganic fertilizer has significantly improved soil bio-physical and chemical properties. Application of VC@10 t ha?1 + 100% RDN (T7) decreased soil bulk density, pH, EC, ESP and Na content to 2.0, 4.2, 26.5, 42.8, and 56.6% respectively and increased soil organic carbon by 34.6% over control (T1). Soil fertility in terms of available N, P, K, Ca, and Mg increased by 20.5, 33.0, 36.4, and 44%, respectively, over control (T1). Soil microbial biomass carbon, nitrogen, and phosphorus also improved significantly due to combined use of organic amendments and inorganic fertilizers over the only use of inorganic fertilizers. Decreasing in soil sodicity and increasing soil fertility showed significant increase (P < 0.05) in crop growth, growth indices, and grain yields of rice and wheat. The study revealed that combined use of VC or MSW compost @10 t ha?1 in conjunction with 75% RDN through inorganic fertilizers in sodic soils proved sustainable technology for restoration of degraded sodic soils and improving crop productivity.  相似文献   

19.
ABSTRACT

Amendments are commonly applied to soil to ameliorate sodic conditions, but their effect on improving microbial activity depends on the severity of sodicity and the types and rates of amendments applied. Changes in metabolic activity in response to three chemical amendments (flue-gas gypsum (FG), spent lime, and langbeinite) applied at three rates to two sodic soils were measured using infrared gas analyzer during 76 days of incubation. Spent lime had the greatest influence on microbial activity at rates of 33.6 and 67.2 Mg ha?1, and at the highest rate of application (67.2 Mg ha?1) cumulative respiration was over two times greater than the control for both soils. High rates of langbeinite yielded the lowest respiration but were not significantly different than the control and the FG had no significant influence on respiration. The use of spent lime increased microbial activity which, in turn, may improve soil health through increased microbial activity.  相似文献   

20.
以黄土高原南部半湿润易旱区已进行17年的田间定位试验为研究对象,研究了不同培肥措施(不施肥、施用氮磷钾及氮磷钾与有机肥配合施用)下两种种植制度(一年1熟及一年两熟)和撂荒对土壤微生物量碳、氮(SMBC、SMBN)及可溶性有机碳、氮(SOC、SON)等含量的影响.结果表明,与一年1熟的小麦一休闲种植制度相比,一年两熟小麦一玉米轮作提高了0～10 cm土层SMBC、SMBN、有机碳(TOC)、全氮(TN)和土壤SOC、SON的含量,而对10～20 cm土层上述测定指标影响不大.与不施肥(CK)或单施化肥处理(NPK)下小麦-休闲和小麦-玉米轮作方式相比,撂荒处理显著提高了0～10 cm土层各测定指标的含量.不同培肥措施相比,氮磷钾配施有机肥显著提高了0～10 cm、10～20 cm土层SMBC、SMBN含量;NPK处理0～10 cm土层SMBN含量显著增加,10～20 cm土层SMBN和0～10 cm、10～20 cm土层SMBC含量增加但未达显著水平.不同培肥措施和种植制度对SMBC/TOC和SMBN/TN的比例无明显影响.  相似文献   

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