不同轮作序列对旱地胡麻土壤有机碳稳定性的影响   总被引：1，自引：0，他引：1  

刘栋  崔政军  高玉红  剡斌  张中凯  吴兵  谢亚萍  牛俊义 《草业学报》2018,27(12):45-57

为了探索陇中黄土高原半干旱丘陵沟壑区胡麻轮作序列对土壤碳库的影响,2012-2016年通过4年定位试验,以连作为对照,研究了不同胡麻频率下的轮作序列(F:休闲;PWFW:25%Flax、马铃薯-小麦-胡麻-小麦;WFWP:25%Flax、小麦-胡麻-小麦-马铃薯;FWPF:50%Flax、胡麻-小麦-马铃薯-胡麻;WPFF:50%Flax、小麦-马铃薯-胡麻-胡麻;FFFF:100%Flax、胡麻-胡麻-胡麻-胡麻)对土壤团聚体、总有机碳(TOC)、土壤颗粒有机碳(POC)、土壤微生物碳(MBC)和氮(MBN)的影响。结果表明,休闲、不同轮作序列和低胡麻频率显著增加了030 cm土层<0.25 mm粒级的土壤团聚体含量、TOC和POC含量,而随胡麻频率的增加三者的含量呈下降趋势。其中,25%Flax处理下土壤团聚体含量较播前和休闲处理分别显著增加了2.02%4.04%和9.56%11.73%;土壤有机碳(SOC)较连作显著增加5.95%7.48%。50%Flax处理下胡麻位置对土壤SOC影响显著,且轮作(FWPF)显著高于连作(WPFF)。060 cm土层土壤SOC含量表现为休闲>播前≈25%Flax>50%Flax>100%Flax。与连作相比,轮作显著提高了010 cm土层土壤TOC和POC含量,呈现表层富集现象。土壤POC含量表现为25%Flax≈休闲>50%Flax>100%Flax。此外,轮作换茬显著增加了土壤MBC含量,且随着胡麻频率的增加,030 cm土层土壤MBC含量逐渐降低。与播前、休闲、轮作相比,连作显著降低土壤微生物碳氮比,50%Flax(WPFF)轮作序列和土层深度对土壤有机碳和微生物量的互作效应显著。综合来看,休闲可以显著改善土壤理化性状,25%胡麻频率的轮作序列利于保持土壤团聚体稳定性,增加土壤TOC、SOC和POC含量,而50%Flax轮作序列(WPFF)能够提高土壤微生物量和微生物碳氮比。表明25%胡麻频率的轮作序列均可维持土壤有机碳的稳定性,是旱地胡麻比较理想的轮作序列。  相似文献   

土壤易氧化有机碳与溶解性有机碳对荒漠草地沙漠化过程中土壤碳库变异的表征     

阎欣  刘任涛  安慧 《草业学报》2018,27(11):15-25

以干旱、半干旱地区荒漠草地不同沙漠化阶段土壤为研究对象,研究不同沙漠化阶段土壤易氧化有机碳与溶解性有机碳含量和分配比例变异规律,分析不同沙漠化阶段土壤碳库指数变化,探讨荒漠草地沙漠化过程中土壤易氧化有机碳与溶解性有机碳对土壤碳库的表征作用。结果表明,随着荒漠草地沙漠化程度的加剧,易氧化有机碳含量表现出一定的波动性,但整体呈下降趋势,溶解性有机碳含量呈线性下降。易氧化有机碳和溶解性有机碳分配比例均在荒漠草地达到最大值,在半固定沙地达到最小值。利用易氧化有机碳含量计算的土壤碳库管理指数随荒漠草地沙漠化程度增加表现出先下降后上升趋势,利用溶解性有机碳含量计算的土壤碳库管理指数呈线性下降趋势。易氧化有机碳、溶解性有机碳含量与土壤有机碳均显著正相关,但溶解性有机碳的相关系数略高于易氧化有机碳。通过比较活度敏感指数和碳库管理指数敏感指数发现,荒漠草地逆向演替至固定沙地过程中,易氧化有机碳的各项敏感指数均高于溶解性有机碳。固定沙地演替至流动沙地过程中,溶解性有机碳的各项敏感指数均高于易氧化有机碳,表明易氧化有机碳能够较好地表征荒漠草地沙漠化前期土壤碳库变化,而荒漠草地沙漠化中期和后期利用溶解性有机碳表征效果更好。  相似文献   

Response of labile organic C and N pools to plastic film removal from semiarid farmland soil          下载免费PDF全文

S. S. Luo  L. Zhu  J. L. Liu  L. D. Bu  S. C. Yue  Y. F. Shen  S. Q. Li 《Soil Use and Management》2016,32(4):535-542

To examine the effects of plastic film removal on grain yield and soil organic matter (SOM), a spring maize (Zea may L.) field experiment was conducted for 5 yr at Changwu Agricultural and Ecological Experimental Station of Northwest China. Compared with traditional plastic film mulching during entire growing stages (FM), plastic film removal at the silking stage (RM) resulted in a 6.3% higher average maize yield. Under the RM treatment, soil organic carbon and total nitrogen significantly increased after the 5‐yr cultivation in the 0‐ to 20‐cm layer. Significant increases in extractable organic C (EOC), KMnO₄‐oxidizable C (KMnO₄‐C) and C management index (CMI) in the 0‐ to 20‐cm layer, and light fraction organic C and EOC in the 20‐ to 40‐cm layer were observed in response to plastic film removal after the 1‐yr treatment; the responses were more significant after 5 yr. Under the RM treatment, significant increases in microbial biomass C, light fraction organic N, extractable organic N, KMnO₄‐C and CMI were also observed after five years in the 20‐ to 40‐cm layer. Moreover, KMnO₄‐C and EOC were much more sensitive than other labile SOM fractions to the application of RM, even after only 1 yr of cultivation. Therefore, compared with mulching for the whole growing season, plastic film removal at the maize silking stage is an effective option for increasing yields and enhancing SOM concentration and soil sustainability in the regions with semiarid monsoon climates that have sufficient rainfall during maize reproductive stages.  相似文献   

The Situation for Quinoa and Its Production in Southern Bolivia: From Economic Success to Environmental Disaster     

S.‐E. Jacobsen 《Journal of Agronomy and Crop Science》2011,197(5):390-399

In Bolivia, one of the world’s most important centres of plant domestication, there is growing awareness of the value of native Andean crops, both for domestic consumption and for market sale – notably the virtually boom‐like consumer demand for quinoa around the world. The southern altiplano of Bolivia, south of Oruro, relies almost purely on the production of quinoa and breeding of llamas, which have also been selected as the two commodities of priority to the government to increase the income of the country. Presently, however, quinoa is facing increasing problems in production, owing to its increasing export market and price. The flat areas around the salt desert of the southern altiplano, previously characterized by natural vegetation fed by the llamas, are being increasingly sown with quinoa, hence transformed into deserts, because intensive cultivation methods make the soil loose its fertility. Possible solutions to these problems will require extensive efforts in the south, in addition to various strategies, which also include other parts of the Bolivian altiplano and a strengthened focus on other Andean crops.  相似文献   

Limited effects of land use on soil dissolved organic matter chemistry as assessed by excitation–emission fluorescence spectroscopy and molecular weight fractionation          下载免费PDF全文

P. Roberts  J. M. Gibbons  P. W. Hill  D. L. Jones  M. Farrell 《Soil Use and Management》2016,32(4):662-665

Dissolved organic matter (DOM) in soil solution represents a complex mixture of organic molecules and plays a central role in carbon and nitrogen cycling in plant–microbial–soil systems. We tested whether excitation–emission matrix (EEM) fluorescence spectroscopy can be used to characterize DOM and support previous findings that the majority of DOM is of high molecular weight (MW). EEM fluorescence spectroscopy was used in conjunction with MW fractionation to characterize DOM in soil solution from a grassland soil land management gradient in North Wales, UK. Data analysis suggested that three distinct fluorescence components could be separated and identified from the EEM data. These components were identified as being of humic‐like or fulvic‐like origin. Contrary to expectations, the majority of the fluorescence signal occurred in the small MW (<1 kDa) fraction, although differences between soils from the differently managed grasslands were more apparent in larger MW fractions. We conclude that following further characterization of the chemical composition of the fluorophores, EEM has potential as a sensitive technique for characterizing the small MW phenolic fraction of DOM in soils.  相似文献   

化肥减氮及有机肥配施对水稻产量及土壤养分含量的影响     

解艳玲  贺萌萌  马玲芳  王娟  张骞  谢静波  陈萍 《现代农业科技》2023,(14)

本文旨在研究等磷、钾量条件下，化肥减氮及有机肥不同用量配施对水稻产量及土壤养分的影响，试验共设6个处理，分别为T1∶80%N+20%有机肥；T2∶80%N+40%有机肥；T3∶70%N+60%有机肥；T4∶70%N+80%有机肥；T5∶60%化肥+100%有机肥；CK：100%N+0，对水稻生育期株高、群体动态、产量、构产因子以及秋季土壤养分含量进行分析，结果表明：1化肥减氮20%时，不会对水稻造成明显减产，且当有机肥配施量为500kg·mu-2时，水稻籽粒产量最高，为775.19kg·mu-2，比CK增产17.20%；2有机肥的施用能提高水稻基本苗，对水稻穗长有显著提高效果，对空秕率影响较大，对枝梗数影响最小；3化肥减氮+有机肥配施可以提高土壤肥力，增加土壤有机质含量，提高土壤碱解氮、速效钾含量。  相似文献   

Evaluating biodegradability of soil organic matter by its thermal stability and chemical composition     

《Soil biology & biochemistry》2015

The stability of soil organic matter (SOM) as it relates to resistance to microbial degradation has important implications for nutrient cycling, emission of greenhouse gases, and C sequestration. Hence, there is interest in developing new ways to quantify and characterise the labile and stable forms of SOM. Our objective in this study was to evaluate SOM under widely contrasting management regimes to determine whether the variation in chemical composition and resistance to pyrolysis observed for various constituent C fractions could be related to their resistance to decomposition. Samples from the same soil under permanent pasture, an arable cropping rotation, and chemical fallow were physically fractionated (sand: 2000-50 μm; silt: 50-5 μm, and clay: <5 μm). Biodegradability of the SOM in size fractions and whole soils was assessed in a laboratory mineralization study. Thermal stability was determined by analytical pyrolysis using a Rock-Eval pyrolyser, and chemical composition was characterized by X-ray absorption near-edge structure (XANES) spectroscopy at the C and N K-edges. Relative to the pasture soil, SOM in the arable and fallow soils declined by 30% and 40%, respectively. The mineralization bioassay showed that SOM in whole soil and soil fractions under fallow was less susceptible to biodegradation than that in other management practices. The SOM in the sand fraction was significantly more biodegradable than that in the silt or clay fractions. Analysis by XANES showed a proportional increase in carboxylates and a reduction in amides (protein) and aromatics in the fallow whole soil compared to the pasture and arable soils. Moreover, protein depletion was greatest in the sand fraction of the fallow soil. Sand fractions in fallow and arable soils were, however, relatively enriched in plant-derived phenols, aromatics, and carboxylates compared to the sand fraction of pasture soils. Analytical pyrolysis showed distinct differences in the thermal stability of SOM among the whole soil and their size fractions; it also showed that the loss of SOM generally involved preferential degradation of H-rich compounds. The temperature at which half of the C was pyrolyzed was strongly correlated with mineralizable C, providing good evidence for a link between the biological and thermal stability of SOM.  相似文献   

Environmental stress response limits microbial necromass contributions to soil organic carbon     

《Soil biology & biochemistry》2015

The majority of dead organic material enters the soil carbon pool following initial incorporation into microbial biomass. The decomposition of microbial necromass carbon (C) is, therefore, an important process governing the balance between terrestrial and atmospheric C pools. We tested how abiotic stress (drought), biotic interactions (invertebrate grazing) and physical disturbance influence the biochemistry (C:N ratio and calcium oxalate production) of living fungal cells, and the subsequent stabilization of fungal-derived C after senescence. We traced the fate of ¹³C-labeled necromass from ‘stressed’ and ‘unstressed’ fungi into living soil microbes, dissolved organic carbon (DOC), total soil carbon and respired CO₂. All stressors stimulated the production of calcium oxalate crystals and enhanced the C:N ratios of living fungal mycelia, leading to the formation of ‘recalcitrant’ necromass. Although we were unable to detect consistent effects of stress on the mineralization rates of fungal necromass, a greater proportion of the non-stressed (labile) fungal necromass C was stabilised in soil. Our finding is consistent with the emerging understanding that recalcitrant material is entirely decomposed within soil, but incorporated less efficiently into living microbial biomass and, ultimately, into stable SOC.  相似文献   

44个紫花苜蓿品种的酸铝适应性与耐受性评价     

田政  杨正禹  陆忠杰  罗奔  张茂  董瑞 《草业学报》2023,32(3):142-151

为了解紫花苜蓿在贵州地区的适应性及耐酸铝胁迫机理，以44份紫花苜蓿品种为研究对象，研究紫花苜蓿处于酸铝胁迫下的生理变化，并揭示其生理变化与耐酸铝胁迫间的关系。利用基因与环境互作模型对两个地点1年的紫花苜蓿进行产量分析，筛选出阿尔冈金、新疆大叶苜蓿、Trifecta、Vernal和中牧1号苜蓿5个耐酸铝强适应品种。利用敏感型UC-1465和耐受型阿尔冈金进行酸铝胁迫试验。结果表明：相同处理下，耐受型紫花苜蓿的电导率、相对铝含量、死亡率显著低于敏感型；紫花苜蓿对酸铝胁迫的响应主要通过柠檬酸、苹果酸、乙酸、酒石酸、反丁烯二酸和草酸的显著（P<0.05）增加来体现，其中苹果酸的合成和分泌增多可能是其耐酸铝胁迫的重要原因。  相似文献   

Soil organic carbon stock variability in the Northern Gangetic Plains of India: interaction between agro‐ecological characteristics and cropping systems          下载免费PDF全文

V. K. Singh  M. Rani  B. S. Dwivedi  S. K. Singh  V. K. Gupta  K. Majumdar  R. P. Mishra 《Soil Use and Management》2015,31(4):461-473

Soil organic carbon (SOC) content and its spatial distribution in the Northern Gangetic Plain (NGP) Zone of India were determined to establish the cause–effect relationship between agro‐ecological characteristics, prevailing crop management practices and SOC stock. Area Spread Index (ASI) approach was used to collect soil samples from the NGP areas supporting predominant cropping systems. Exponential ordinary kriging was found most suitable geo‐statistical model for developing SOC surface maps of the NGP. Predicted surface maps indicated that 43.7% area of NGP had 0.5–0.6% SOC, while the rest of the area was equally distributed with high (0.61–0.75%) and low (< 0.5%) SOC content levels. Averaged across cropping systems, maximum SOC content was recorded in Bhabar and Tarai Zone (BTZ), followed by Central Plain Zone (CPZ), Mid‐Western Plain Zone (MWPZ), Western Plain Zone (WPZ) and South‐Western Plain Zone (SWPZ) of the NGP. The SOC stock was above the optimum threshold (> 12.5 Mg/ha) in 97.8, 57.6 and 46.4% areas of BTZ, CPZ and MWPZ, respectively. Only 9.8 and 0.4% area of WPZ and SWPZ, respectively, had SOC stock above the threshold value. The variation in SOC stock was attributed largely to carbon addition through recycling of organic sources, cropping systems, tillage intensity, crop or residue cover and land‐use efficiency, nutrient‐use pattern, soil texture and prevailing ecosystem. Adoption of conservation agriculture, balanced use of nutrients, inclusion of legumes in cropping systems and agro‐forestry were suggested for enhancing SOC stock in the region.  相似文献