首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 31 毫秒
1.
民勤绿洲区苜蓿地土壤有机碳组分分布特征   总被引：1，自引：0，他引：1  
为了解西北民勤绿洲区紫花苜蓿种植后土壤有机碳组分的变化趋势及影响因素,以民勤绿洲区3a(A3)、14a(A14)和22a(A22)苜蓿种植地为研究对象,以棉花种植地(CK)为对照,通过野外调查取样以及室内测试分析,对土壤中的全部有机碳(TOC)、重组有机碳(HFOC)、轻组有机碳(LFOC)、颗粒有机碳(POC)和微生物量碳(MBC)的含量进行测定,分析变化趋势并对其规律进行研究。结果表明:相对于棉花种植地,22a苜蓿地土壤容重和电导率分别降低了13.9%和95.4%。3~22a苜蓿地较棉花种植地(CK)的TOC、LFOC、HFOC和MBC分别表现出175.0%,1 416.0%,47.8%和216.0%的增长幅度,变化差异较为显著。在垂直剖面上,棉花种植地(CK)显著低于苜蓿地LFOC、POC、MBC含量,并随土层加深而不断降低。逐步回归分析表明LFOC与TOC显著正相关(p0.05)。苜蓿种植年限、土层以及这两个变量的交互作用对POC/TOC产生显著影响(p0.01),对TOC、LFOC、HFOC、POC、MBC、LFOC/TOC、HFOC/TOC和MBC/TOC均产生极显著影响(p0.001)。苜蓿种植提高了土壤质量,降低了土壤容重和盐碱性,连续种植14a是苜蓿最为合理的种植年限,同时苜蓿种植有利于0—60cm垂直土层有机碳组分的累积,尤其对TOC、LFOC和MBC的增长效果极其显著。  相似文献   

2.
黄土高原半湿润区苜蓿草地土壤氮素消耗特征研究   总被引：3，自引：2，他引：3  
本文研究了黄土高原地区生长年限分别为4a、6a、10a、12a、18a及26a苜蓿草地土壤氮素的变化特征。结果表明,在0—1000 cm土层,不同生长年限苜蓿草地土壤全氮与碱解氮含量呈现规律性的变化,即随土层深度的增加,全氮及碱解氮含量下降,350cm土层以下,变化趋势平缓。在0—200 cm土层,26a苜蓿草地全氮、碱解氮含量低于4a、6a苜蓿草地,高于10a、12a苜蓿草地;在200—1000 cm土层,土壤全氮、碱解氮含量在不同生长年限之间差异不大,表明苜蓿生长超过一定年限,土壤氮素有一定恢复,但受土壤氮素累计消耗的影响,只能使土壤上层的氮素逐步得到恢复,而深层土壤氮素难以恢复;苜蓿草地有机碳与全氮、碱解氮及C:N之间均为正相关关系。苜蓿生长6a以后,应对苜蓿草地进行合理施肥,以维持苜蓿草地氮素平衡。  相似文献   

3.
《Geoderma》2005,124(1-2):133-142
As an essential indicator of soil quality, soil organic carbon (SOC) and its fractions play an important role in many soil chemical, physical, and biological properties. A 4-year field experiment was conducted to determine the effects of different nutrient and water regimes on paddy soil organic carbon quality by measuring the major SOC fractions. Four nutrient regimes were compared: (i) control; (ii) chemical fertilizers only (CF), (iii) combined application of chemical fertilizers with farmyard manure (FYM) (CM), and (iv) combined application of chemical fertilizers and wheat straw (CS). Two soil water regimes included continuous waterlogging (CWL) and alternate wetting and drying (AWD). The total organic carbon (TOC) and total nitrogen (TN) in paddy soil were 40–60% and 37–67% higher in the combined organic sources and chemical fertilizers treatment against the sole chemical fertilizers treatment (CF), especially under continuous waterlogging (CWL). By fractionalizing SOC, it was observed that, under the water regimes of CWL, easily oxidizable carbon (EOC), particulate organic carbon (POC), light fraction organic carbon (LFOC), microbial biomass carbon (MBC), and mineralizable organic carbon (MNC) in the organically treated paddy soil were significantly (P<0.05) lower, as compared with alternate wetting and drying (AWD). Especially for CM treatment, EOC, POC, LFOC, MBC, and MNC in the paddy soils under the regime of CWL were 23.5%, 32.7%, 16.3%, 56.8% and 25.1% lower than those by AWD, respectively. The proportions of EOC, POC, LFOC, MBC and MNC as a percent of TOC in the CWL were lower than those in the AWD, especially for the CM treatment. In the water regime of CWL, no significant differences were seen in the corresponding proportion of all the investigated organic fractions to soil total organic carbon (TOC) among the three fertilization treatments, whereas in the AWD, the corresponding proportions of different carbon fractions to TOC in the organic fertilizer treatments were significantly (P<0.05) higher than those in the chemical fertilizer treatment. Under continuous waterlogging, the proportion of soil water stable aggregate >250 μm (WSA) decreased by 42–45% and clay dispersion ratio (RCD) increased by 12–38%, as compared to the water regimes of AWD, when FYM or wheat straw was incorporated into paddy soil. Correlation analysis showed that, under the water regimes of AWD, WSA was significantly and positively related to EOC, LFOC and POC with the coefficients (r) of 0.822, 0.889, 0.912 (P<0.01), respectively. RCD was negatively correlated to EOC, LFOC and POC with the r=−0.796, −0.854, and −0.897 (P<0.01), respectively, under AWD. Under the water regimes of CWL, there were no significant (P<0.05) correlations between WSA as well as RCD and any organic carbon fraction except POC.  相似文献   

4.

Purpose

Land use changes have a significant impact on soil carbon emission and sequestration worldwide. Accurate evaluation of the effect of land use change (cultivation and abandonment) on soil carbon content of subalpine meadows is required to monitor the soil carbon dynamics of rangeland ecosystems in China.

Materials and methods

Based on collection of soil cores and vegetation, investigations of four types of land use (undisturbed natural meadow, land cultivated for 20?years, land abandoned for 3?years following cultivation, and land abandoned for 10?years following cultivation) were undertaken in the headwater area of the Heihe River in northwest China. Three soil carbon fractions [soil organic carbon (SOC), light fraction organic carbon (LFOC), and microorganism biomass carbon (MBC)] were determined in the laboratory, and the relative abundances of LFOC/SOC and MBC/SOC were calculated.

Results and discussion

Repeated cultivation by ploughing reduced the carbon content of the top soil layer, resulting in more uniform vertical distribution of soil organic matter. Ten years after cessation of cultivation, the organic carbon content within the top 10-cm soil layer (0?C10?cm) had reached 90?% of the content in native meadows, equivalent to a mean annual sequestration rate of 1.73?t?C?ha?1. The rate of LFOC restoration was faster than that of SOC restoration. The variation in the ratio of MBC to SOC (0.91?C1.07?%) was small.

Conclusions

The activity of cultivation reduced all indicators of soil carbon status, which were not completely restored to the level of natural meadow, even after abandonment of cultivation for 10?years. Nevertheless, abandonment of cultivation is a practical, even if long-term, means of improving carbon sequestration in subalpine meadow of China.  相似文献   

5.
碳氮添加对雨养农田土壤全氮、有机碳及其组分的影响   总被引：2，自引：1，他引：1  
江晶  武均  张仁陟  董博  蔡立群 《水土保持学报》2019,33(3):215-220,227
为探明碳氮添加4年后,土壤全氮、有机碳及其组分(可溶性有机碳、微生物量碳、轻组和重组有机碳)的变化特征,依托布设于甘肃省定西市安定区李家堡镇的不同碳源配施氮素田间定位试验,涉及秸秆、生物质炭、氮素3个因素,秸秆设置为不施、施用秸秆2水平;生物质炭为不施和施用生物质炭2个水平;氮素设置为不施氮、施纯氮50 kg/hm^2、施纯氮100 kg/hm^2 3个水平,共9个处理。结果表明:不同处理下土壤全氮、有机碳及其组分的含量均随土层的加深而降低。添加生物质炭对土壤全氮、有机碳及其组分均具有不同程度的提升效应。添加秸秆对土壤全氮、有机碳和可溶性有机碳、微生物量碳、轻组有机碳均具有显著提升效应,仅在0-5 cm土层对重组有机碳有显著提高。添加氮素可显著提升土壤全氮、有机碳和可溶性有机碳、微生物量碳、轻组有机碳含量。较其他处理,添加生物质炭对土壤全氮、有机碳和重组有机碳的提升效应最高,添加秸秆对可溶性有机碳、微生物量碳、轻组有机碳的提升效果最优。从提升土壤质量的角度出发,推荐秸秆配施氮素模式,该模式下土壤碳素有效性高、易于被微生物利用,有利于作物生长。从提高土壤固碳角度考虑,推荐生物质炭配施氮素模式,该模式有利于碳的封存。  相似文献   

6.
ABSTRACT

The performance of DNDC (DeNitrification-DeComposition) and RothC (Rothamsted Carbon model) in simulating soil organic carbon (SOC) storage in soils under rice (Oryza sativa L.) – wheat (Triticum aestivum L.), maize (Zea mays L.) – wheat and cotton (Gossypium hirsutum L.) – wheat cropping systems was evaluated on field and regional scale. Field experiments consisted of N, NP, NK, PK, NPK, FYM, N + FYM, NPK + FYM, and control (UF) treatments. DNDC and RothC over-estimated SOC storage by 0.35–1.16 Mg C ha?1 (6–21%) in surface layer with manure application, compared with inorganic fertilizer treatments by 1.01–1.16 Mg C ha?1 (14–18%). Although RothC only slightly over-estimated SOC stocks, DNDC provided a better match for measured versus simulated SOC stocks (R 2 = 0.783*, DNDC; 0.669*, RothC, p < .05). Model validation on independent datasets from long-term studies on rice–wheat (R 2 = 0.935**, DNDC; R 2 = 0.920**, RothC, p < .01) and maize–wheat (R 2 = 0.895** for DNDC and R 2 = 0.967** for RothC, p < .01) systems showed excellent agreement between measured and simulated SOC stocks. On a regional scale, change in SOC storage under Scenario 1 (NPK) was significant up to 8 years of simulation, with no change thereafter. In Scenario 2 (NPK + FYM), DNDC simulated SOC storage after 10 years was 2.0, 0.4, and 1.4 Mg C ha?1 in three systems, respectively. Amount of C sequestered in silt + clay fraction varied between 0.31 and 0.97 kg C 10 years?1 (Mg silt + clay)?1 under Scenario 1, and between 0.78 and 2.67 kg C 10 years?1 (Mg silt + clay)?1 under Scenario 2.  相似文献   

7.
张宇婕  于亚军 《土壤》2019,51(4):732-738
土壤有机碳含量是土壤肥力状况的重要标志之一,其活性组分对田间管理措施反映敏感。因此,分析煤矸山复垦重构土壤有机碳含量及其组分差异对于揭示土壤碳库变化、指导复垦地田间管理措施的实施有重要意义。本研究以山西省霍州曹村煤矸山复垦后5a(R-5a)、7a(R-7a)和9a(R-9a)的果园为对象,通过与当地原地貌果园(CK)对比,分析了3种复垦样地土壤总有机碳(TOC)及其组分可溶性有机碳(DOC)、微生物生物量碳(MBC)、轻组有机碳(LFOC)和重组有机碳(HFOC)的差异,以及与土壤环境因子间的关系。结果表明:①随复垦年限的增加,3种复垦样地土壤TOC、LFOC和HFOC含量均呈先增后减趋势,DOC含量呈增加趋势,MBC含量呈先减后增趋势;但与CK相比,3种复垦样地土壤TOC、DOC、MBC、LFOC和HFOC含量均明显偏低。②DOC/TOC和MBC/TOC在R-7a样地中最低,LFOC/TOC随复垦年限的增加呈增加趋势,HFOC/TOC呈减少趋势,表明土壤中更多的有机碳从稳定态转变为活性态。③土壤全氮、全磷、碱解氮、碳氮比、黏粒含量、pH和含水量均不同程度影响有机碳含量,其中全氮、全磷、黏粒含量和土壤pH为关键因子。  相似文献   

8.
Alpine grasslands with a high soil organic carbon(SOC)storage on the Tibetan Plateau are experiencing rapid climate warming and anthropogenic nitrogen(N)deposition;this is expected to substantially increase the soil N availability,which may impact carbon(C)cycling.However,little is known regarding how N enrichment influences soil microbial communities and functions relative to C cycling in this region.We conducted a 4-year field experiment on an alpine grassland to evaluate the effects of four different rates of N addition(0,25,50,and 100 kg N ha^-1 year^-1)on the abundance and community structure(phospholipid fatty acids,PLFAs)of microbes,enzyme activities,and community level physiological profiles(CLPP)in soil.We found that N addition increased the microbial biomass C(MBC)and N(MBN),along with an increased abundance of bacterial PLFAs,especially Gram-negative bacterial PLFAs,with a decreasing ratio of Gram-positive to Gram-negative bacteria.The N addition also stimulated the growth of fungi,especially arbuscular mycorrhizal fungi,reducing the ratio of fungi to bacteria.Microbial functional diversity and activity of enzymes involved in C cycling(β-1,4-glucosidase and phenol oxidase)and N cycling(β-1,4-N-acetyl-glucosaminidase and leucine aminopeptidase)increased after N addition,resulting in a loss of SOC.A meta-analysis showed that the soil C/N ratio was a key factor in the response of oxidase activity to N amendment,suggesting that the responses of soil microbial functions,which are linked to C turnover relative to N input,primarily depended upon the soil C/N ratio.Overall,our findings highlight that N addition has a positive influence on microbial communities and their associated functions,which may reduce soil C storage in alpine grasslands under global change scenarios.  相似文献   

9.
A study was conducted to investigate how management affects soil carbon (C) pools, mineralization kinetics, and related microbiological properties. Soils were sampled from two sites in central Iran. At the Lordegan forest (LOR) site, soil under an oak forest was compared with its adjacent deforested counterpart. At the Fozveh Research Station (FRS) site, adjacent fields under alfalfa and tall fescue cropping were compared. At the LOR site, soil organic C (SOC), total nitrogen (TN), microbial biomass C (MBC), β-glucosidase activity (βG), and potentially mineralizable C (C0) were significantly greater in the forest than in the deforested counterpart. At the FRS site, the soil cropped to alfalfa showed significantly greater values of SOC, TN, MBC, βG, and C0 than that cropped to tall fescue. Overall, soil biodegradable C pools and related processes are largely affected by management practices in the semiarid to arid environments, confirming the role of management as a significant driver of soil C change.  相似文献   

10.
Microbial biomass C (MBC) is one of the soil properties used as an indicator for the fertility status of a soil. A study was conducted on a semi-arid Loess Plateau in China. The field was planted with spring wheat and mulched with plastic film for various lengths of time. Our primary objectives were to (i) explore the influence of film mulching on soil MBC and soil fertility, and (ii) seek an effective approach of maintaining and improving sustainability of cropland mulched with plastic film in two growing seasons. Four treatments were tested, non-mulching (M0), mulching for 30 days after sowing (M30), mulching for 60 DAS (M60) and mulching for the whole growing period (Mw). An increasing air temperature with time within the growing season promoted soil MBC in the two growing seasons, but a severe drought led to a lower MBC in 2000 compared with the wet year of 1999. Film mulching promoted MBC significantly in the 2 years, but decreased soil organic carbon (SOC). SOC is very low in the experimental soil, accounting for the higher MBC/SOC ratio compared with ratios reported by others. The SOC is greatly reduced in the non-mulched and the Mw treatments compared to the M30 and M60 treatments. In conclusion, the benefits of film mulching in semi-arid agricultural systems are enormous but realizing their full potential depends on how long the mulching material is maintained during the growing season. In the system tested, it is desirable to mulch the plots for 30-60 DAS in order to enhance microbial biomass and cycling of nutrients and also to provide a more stable soil micro-environment that generates more residues in the rhizosphere.  相似文献   

11.
长期施肥下黑土活性有机碳变化特征   总被引：4，自引：1，他引：4  
观测分析了黑土长期不同施肥30年后不同形态的活性有机碳含量(易氧化有机碳>轻组有机碳>微生物量碳>水溶性有机碳)的变化特征。结果表明,长期施用氮、氮磷和氮磷钾化肥对土壤活性有机碳无显著影响;长期施用有机肥以及有机肥配施化肥均显著提高了土壤活性有机碳含量,与不施有机肥相比,有机肥区组中土壤轻组有机碳和水溶性有机碳含量增幅较大,分别在122%～258%和237%～351%之间,而土壤易氧化有机碳和微生物量碳含量增幅分别在72%～98%和83%～112%。黑土不同形态活性有机碳对施肥的响应灵敏度为,轻组有机碳>水溶性有机碳>微生物量碳≈易氧化有机碳。因此,轻组有机碳是指示土壤有机碳变化的较好指标。  相似文献   

12.
黄土高原地区土壤干化导致林草植被大面积衰退,研究苜蓿草地土壤水分消耗规律对该区农业持续发展及生态环境恢复具有重要的理论意义。该文研究了黄土高原地区不同生长年限苜蓿草地1 000 cm土层土壤水分的变化特征及其对土壤水分生态环境的影响。结果表明：在0～1 000 cm土层,4年、6年生苜蓿草地土壤水分条件最好;12年、18年、26年生苜蓿草地土壤水分条件最差。在黄土高原地区,苜蓿地土壤干层出现的区域及发生的程度不同。4年、6年、8年生苜蓿草地,对土壤水分生态环境不会产生不利影响;12年、18年、26年生苜蓿草地,对土壤水分生态环境产生深刻负面影响。研究表明在陇东黄土高原地区苜蓿生长6 a后,应实施粮草轮作,以恢复土壤水分,持续提高土地生产力水平。  相似文献   

13.
长期施用有机肥对稻麦轮作体系土壤有机碳氮组分的影响   总被引：5，自引：1，他引：4  
【目的】 以湖北武汉地区长期稻麦轮作制度下施肥试验地作为研究对象,研究了长期不同施肥处理对耕层土壤有机碳、全氮及活性碳氮组分的影响,为优化稻麦轮作体系下施肥措施,实现土壤固碳减排,培肥土壤提供理论依据。 【方法】 长期施肥试验开始于1981年,试验处理包括不施肥 (CK)、施化学氮肥 (N)、施化学氮磷肥 (NP)、施化学氮磷钾肥 (NPK)、单施有机肥 (M) 及有机无机肥配施处理 (NPKM)。收集2017年小麦收获后耕层 (0—20 cm) 土壤,测定各小区土壤中的有机碳 (SOC)、全氮 (TN)、微生物量碳氮 (MBC、MBN)、水溶性碳 (DOC)、热水溶性有机碳 (HWSC)、颗粒有机碳氮 (POC和PON)、轻组有机碳氮 (LFOC和LFON) 及氯化钾浸提氮 (KEN,即水溶性无机氮) 的含量并分析各指标间的关系。 【结果】 1) 除KEN外,长期施用有机肥显著增加耕层土壤的各碳氮组分含量,特别是有机无机肥配施处理。2) 各活性有机碳组分占SOC的百分比由高到低排序为POC > LFOC > HWSC > MBC > DOC,各氮组分占TN的百分比由高到低排序为PON > LFON > MBN > KEN,其中POC占SOC的24.04%～37.64%,PON占TN的12.09%～20.24%,且有机肥处理下POC/SOC、PON/TN显著高于其余处理。3) 通过对土壤有机碳及各活性有机碳的对施肥的敏感性分析可得,各活性碳敏感性指数均显著高于SOC,且DOC的敏感性最高。4) 通过各组分间相关性分析可知,除KEN外,各碳、氮组分间显著正相关,其中DOC与SOC、PON与TN关系更为紧密,表明DOC及PON可较好地反应出SOC、TN的变化情况。 【结论】 在湖北稻麦轮作地区,长期有机无机肥配施处理显著增加了土壤碳库及氮库,促进了土壤碳、氮的积累,尤其是颗粒有机碳和有机氮 (POC和PON)。水溶性碳 (DOC) 对施肥反应最为敏感,可作为指示该地区有机物早期变化的指示物。   相似文献   

14.
Soil organic carbon (SOC) and its different labile fractions are important in minimizing negative environmental impacts and improving soil quality. However, very little is known of the dynamics of SOC and its labile fractions after the cultivated wetlands have been abandoned in northeast China. The objectives of this study were (1) to estimate the dynamics of SOC after the abandonment of cultivated soil, (2) to investigate the most sensitive fraction for detecting changes in organic C due to the abandonment of cultivated soil, and (3) to explore the key factors affecting the dynamics of soil C after the abandonment of cultivated soil in the freshwater marsh region of northeast China. Our results showed that the abandonment of cultivated wetlands resulted in an increase in SOC and the availability of C. The SOC content increased to 31, 44, and 107 g kg−1 after these cultivated wetlands were abandoned for 1, 6, and 13 years, respectively, as compared to an SOC content of 28 g kg−1 in the soil that had been cultivated on for 9 years. In northeast China, where a cultivated wetland was abandoned, the initial regeneration of SOC pools was considerably rapid and in accordance with the Boltzmann equation. An analysis of the stepwise regression indicated that the dynamics of SOC (g kg−1) can be quantitatively described by a linear combination of the root density and the mean soil temperature 5 cm underground in the growing season, as expressed by the following relationship: TOC = 0.008 root density −3.264T + 96.044 (R2 = 0.67, n = 9, p < 0.05. T is the mean soil temperature 5 cm underground in the growing season), indicating that approximately 67% of the variability in SOC can be explained by these two parameters. The root biomass was the key factor affecting SOC concentration according to the observation made during the recovery of cultivated soil that was abandoned. Soil temperature indirectly influenced the SOC concentration by affecting soil microbial activity. The abandonment of cultivated wetlands resulted in an increase in the light-fraction organic C (LF-OC), microbial biomass C (MBC), and dissolved organic C (DOC) concentration. The rate of increase in LF-OC was considerably higher than that in SOC and HF-OC. Similarly, the rate of increase in MBC was also considerably higher than that in SOC in cultivated soils abandoned for 4–8 years. However, the rate of increase in DOC was far lower than that in SOC. The R2 value for the correlation between the increments of the LF-OC and SOC was significantly higher than that for the correlation between DOC and MBC (0.99 vs. 0.90), indicating that LF-OC was the most sensitive fraction for detecting changes in organic C due to the abandonment of cultivated soil.  相似文献   

15.
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-CO2 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   

16.
Cropland (CP), native grassland (NG) and two shrub land treatments which were converted from cropland in 1985:seabuckthorn (Hippophae rhamnoides L. ) (ST), and branchytamarisk (Tamarix ramosissima) (BT) were investigated to evaluate effects of land use conversion on soil organic carbon (SOC) and soil nutrients in the semi-arid region of the Loess Plateau of China. Total organic carbon (TOC), light fraction organic carbon (LFOC), heavy fraction organic carbon (HFOC), total N (TN), nitrate nitrogen (NO3--N) and nitrite nitrogen (NO2--N), ammonium nitrogen (NH4+-N), total P, and available P (AP) were measured. The results showed that SOC in NG, ST and BT were 12.7%, 27.7% and 34.8% higher than that of the cropland, respectively. LFOC, light fraction (LF) dry matter, ratio of TOC to TN (C/N) and the ratio of TOC to AP (C/P) were higher in the shrub land or native grassland than in the cropland. Cropland had the highest TN, the sum of NO3--N and NO2--N, TP and AP due to the use of chemical fertilizers. TOC significantly correlated with LFOC, HFOC and C/N. LFOC significantly correlated with dry matter of the LF and C/N. TN, the sum of NO3--N and NO2--N and AP were significantly negatively correlated with TOC and LFOC. Therefore, land use conversion from cropland to shrub land, or maybe grassland, contributed to SOC sequestration and improved soil nutrients stabilization.  相似文献   

17.
农田土壤的固碳潜力对于理解陆地生态系统碳循环和气候变化至关重要.分别选取亚热带区4种典型稻田和旱地土壤,设置裸土光照和裸土黑暗处理,探讨土壤有机碳(SOC)及其活性组分(可溶性有机碳(DOC)和微生物生物量碳(MBC))对光照和黑暗条件的响应。结果表明,与培养前相比,培养80 d后,光照和黑暗培养下稻田及旱地土壤SOC含量差异不显著,这可能与土壤SOC含量变化是一个缓慢的过程有关.光照和黑暗培养均显著提高了土壤DOC含量(与培养前相比,光照和遮光培养平均分别提高73.37%和80.58%),而MBC显著降低(与培养前相比,光照和遮光培养平均分别降低35.58%和32.32%)。相关分析表明,培养后的土壤DOC含量与土壤粘粒含量呈极显著正相关性(P<0.01),而与土壤原有碳氮水平呈极显著负相关;土壤MBC则恰好相反,MBC与土壤粘粒含量呈极显著负相关,而与土壤原有碳氮水平呈极显著正相关.本研究表明,短期(80d)的光照和黑暗培养对稻田及旱地土壤SOC含量变化影响不大,而显著改变了有机碳活性组分(DOC和MBC)含量,进一步说明了土壤活性有机碳是土壤中活性化学组分,随环境条件变化表现出强烈的变化趋势。  相似文献   

18.
Soil samples taken from four experimental sites that had been cropped to continuous corn for 3–11 years in Ontario and Quebec were analyzed to evaluate changes in quantity and quality of labile soil organic carbon under different nitrogen (N) fertility and tillage treatments. Addition of fertilizer N above soil test recommendations tended to decrease amounts of water-soluble organic carbon (WSOC) and microbial biomass carbon (MBC). The quality of the WSOC was characterized by 13C nuclear magnetic resonance and infrared spectrophotometry and the results indicated that carbohydrates, long-chain aliphatics and proteins were the major components of all extracts. Similar types of C were present in all of the soils, but an influence of management was evident. The quantity of soil MBC was positively related to the quantities of WSOC, carbohydrate C, and organic C, and negatively related to quantities of long-chain aliphatic C in the soil. The quantity of WSOC was positively related to the quantities of protein C, carbohydrate C, and negatively related to the quantity of carboxylic C. The quantity of soil MBC was not only related to quantities of soil WSOC but also to the quality of soil WSOC. Received: 2 April 1997  相似文献   

19.
在洞庭湖区的2km2典型样区内,按3个/hm2的密度采集土样,分析不同耕种方式下(水稻、水旱轮作油菜、水改旱种苎麻1~5年)水稻土壤的有机碳、全氮和全磷含量状况。结果表明,水稻田土壤有机碳、全氮和全磷含量水平均较高,水田改为旱地后土壤有机碳、全氮含量及C/N比值有较大幅度的下降,但全磷含量变化不大。土壤有机碳、全氮及C/N比值均以水稻田土壤>油菜地土壤>苎麻地土壤,与水稻田相比,油菜土壤有机碳平均下降了11.19%、全氮下降了10.33%,而苎麻土壤有机碳平均下降了35.57%、全氮下降了31.61%。土壤有机碳与全氮之间呈线性关系,相关性均达极显著水平(P<0.01)。  相似文献   

20.
  目的  探究西南喀斯特土壤碳（C）、氮（N）、磷（P）化学计量特征和酶活性对不同土地利用方式的响应,有利于为西南喀斯特的土地利用调控与生态修复提供决策支持。  方法  本研究以喀斯特高原峡谷（贵州省关岭县花江研究区）亚热带森林（SUF）、疏林（SPF）、灌木林（SHF）、草地（GL）、玉米地（CL）、裸地（BL）及弃荒地（AL）的土壤为研究对象,通过采集其0 ~ 15 cm土层样品,分析土壤C、N、P化学计量特征及酶活性的差异。  结果  ①土壤有机碳含量（SOC）和全氮（TN）含量表现为SPF > AL > BL > SHF > CL > SUF > GL,土壤全磷（TP）含量表现为AL > BL > CL > SPF > GL > SHF > SUF。C∶N表现为SUF > AL > SPF > SHF > CL > BL > GL,C∶P表现为SPF > SUF > SHF > CL > AL > GL > BL,N∶P表现为SPF > SHF > SUF > CL > GL > AL > BL。土壤微生物量碳（MBC）含量则是SPF > SHF > CL > AL > SUF > BL > GL。②脲酶（URE）活性表现为SUF > CL > SPF > SHF > AL > GL > BL,蔗糖酶（SUC）活性表现为BL > AL > SPF > CL > SHF > GL > SUF,碱性磷酸酶（ALP）活性表现为SUF > BL > SHF > SPF > AL > CL > GL,过氧化氢酶（CAT）活性则是CL > AL > BL > SHF > SPF > GL > SUF。③URE与C∶P、N∶P、MBC极显著正相关,与C∶N显著正相关,与TP显著负相关;SUC与TP极显著正相关,与SOC、TN显著正相关;ALP与C∶N、C∶P显著正相关;CAT与TP极显著正相关,与TN显著正相关,与C∶P显著负相关。④在前两个排序轴中土壤理化因子累计解释了土壤酶活性变化的84.83%,按重要性排序依次为pH > 土壤温度 > TP > C∶P > TN > 容重 > SOC > C∶N > N∶P > MBC。  结论  不同土地利用方式土壤C、N、P化学计量特征及酶活性存在显著差异,土壤N∶P < 14表明土壤养分主要受氮限制。影响酶活性的主要土壤理化因子为土壤pH、土壤温度和土壤全磷。  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号