不同地表覆盖栽培对旱地土壤有机碳、无机碳和轻质有机碳的影响

通过田间长期定位试验,分层采集冬小麦-休闲种植体系0—40 cm土层的土样,研究了常规、地表覆膜和覆草栽培对土壤有机碳、无机碳和轻质有机碳的影响。结果表明,覆膜或覆草可以显著增加地上部小麦生物量和子粒产量。不同地表覆盖对0—40 cm土层的无机碳含量和分布无显著影响,但与常规栽培相比,地表覆膜使0—5 cm土层的有机碳含量显著降低,0—40 cm各土层轻质有机碳表现出明显降低趋势,平均降低 C 6.1~74.5 mg/kg;地表覆草却表现出明显增加土壤轻质有机碳的趋势,0—5,5—10,10—20 cm土层的轻质有机碳含量分别增加C 235.2、190.0和144.9 mg/kg,相当于常规的38.7%,32.9%和34.5%。同时,覆草栽培还表现出降低0—10 cm土层轻质有机质含碳量的趋势,并使0—20 cm土层轻质有机碳占有机碳的比例显著高于常规栽培和地表覆膜处理。可见,地表长期覆膜不利于旱地土壤有机碳累积,覆草不仅可以增加表层土壤的轻质有机碳累积,还可改善土壤碳氮组成。     

造林恢复植被后土壤的化学计量学特征对其碳组分的影响

Afforestation is recognized as an important driving force for soil organic C(SOC) dynamics and soil element cycling.To evaluate the relationships between soil C:N:P stoichiometry and SOC fractions,soil C:N:P stoichiometry distributions at 0–200 cm soil depths were analyzed and the contents of SOC fractions were evaluated in 9 typical land-use systems on the Loess Plateau of China.The contents of light fraction organic C,particulate organic C(53,53–2 000,and2 000 μm),labile organic C,microbial biomass C,and dissolved organic C decreased with increasing soil depth and were higher in afforested soil than in slope cropland soil.Compared with the slope cropland,different vegetation types influenced soil C:N,C:P,and N:P ratios,especially when C:P and N:P ratios were significantly higher(P0.05).Moreover,SOC fractions at the 0–10 and 10–40 cm depths were particularly affected by soil C:P ratio,whereas those at the 40–100 and 100–200 cm soil depths were significantly affected(P0.05) by soil N:P ratio.These results indicate that changes in SOC fractions are largely driven by soil C:P and N:P ratios at different soil depths after afforestation.     

蔬菜连作对铜尾矿土壤中有机碳、腐殖质碳以及可溶性有机碳的影响

Carbon of humus acids （HSAC） and dissolved organic carbon （DOC） are the most active forms of soil organic carbon （SOC） and play an important role in global carbon recycling. We investigated the concentrations of HSAC, water-soluble organic carbon （WSOC）, hot water-extractable organic carbon （HWOC） and SOC in soils under different vegetation types of four copper mine tailings sites with differing vegetation succession time periods in Tongling, China. The concentrations of HSAC, WSOC, HWOC and SOC increased with vegetation succession. WSOC concentration increased with the accumulation of SOC in the tailings, and a linearly positive correlation existed between the concentrations of HSAC and SOC in the tailings. However, the percentages of HSAC and DOC in the SOC decreased during vegetation succession. The rate of SOC accumulation was higher when the succession time was longer than 20 years, whereas the speeds of soil organic matter （SOM） decomposition and humification were slow, and the concentrations of HSAC and DOC increased slowly in the tailings. The percentage of carbon of humic acid （HAC） in HSAC increased with vegetation succession, and the values of humification index （HI）, HAC/carbon of fulvic acid, also increased with the accumulation of HSAC and SOC in soils of the tailings sites. However, the HI value in the each of the tailings was less than 0.50. The humification rate of SOM was lower than the accumulation rate of SOM, and the level of soil fertility was still very low in the tailings even after 40 years of natural restoration.     

改良剂作用下滨海盐化潮土团聚体分布、稳定性及有机碳分布特征

通过对滨海盐化潮土小麦—玉米轮作2年田间定位试验,研究不同改良剂施用对土壤团聚体分布、稳定性及土壤团聚体中有机碳含量、各级团聚体有机碳对总有机碳贡献率的影响。试验共设置3个处理:对照(CK)、有机土壤改良剂(OSA)和有机—无机土壤改良剂(CSA),分析土壤团聚体分布、水稳性大团聚体(R_(0.25))、平均重量直径(mean weight diameter,MWD)、几何平均直径(geometric mean diameter,GMD)、分形维数(D)、有机碳储量(soil organic carbon storage,SOCS)和有机碳贡献率(contribution rate of organic carbon)。结果表明,滨海盐化潮土水稳性团聚体组成主要以0.25 mm粒径为主,改良剂施用后土壤R_(0.25)显著提高,其影响主要集中在5 mm和2～5 mm粒径级,OSA处理2个粒级团聚体含量较CK分别显著增加167.38%和59.00%,CSA处理分别显著增加89.17%和100.66%。施用OSA与CSA同时显著提高了土壤团聚体MWD和GMD值,说明2种改良剂的施用均有利于提高大团聚体数量及稳定性。施用改良剂2年处理土壤各粒级团聚体中有机碳含量均有所提高,OSA处理以1～2 mm粒级提高最多,CSA以2～5 mm粒级提高最多,且前者达显著水平。与CK相比,改良剂可促使土壤有机碳向大团聚体富集,显著提高1～2 mm粒级团聚体对土壤总有机碳的贡献率93.62%～109.76%,降低或显著降低1～2 mm粒级团聚体对土壤总有机碳的贡献率20.55%～24.92%。在小麦—玉米轮作模式下,改良剂施用不仅可以显著提高滨海盐化潮土水稳性大团聚体含量和稳定性,还可显著增加水稳性大团聚体有机碳含量与储量,是加强盐碱土壤有机碳库积累的有效措施。     

Enhancing phosphorus availability,soil organic carbon,maize productivity and farm profitability through biochar and organic–inorganic fertilizers in an irrigated maize agroecosystem under semi‐arid climate

Biochar amendments offer promising potential to improve soil fertility, soil organic carbon (SOC) and crop yields; however, a limited research has explored these benefits of biochar in the arid and semi‐arid regions. This two‐year field study investigated the effects of Acacia tree biomass‐derived biochar, applied at 0 and 10 t ha^?1 rates with farmyard manure (FYM) or poultry manure (PM) and mineral phosphorus (P) fertilizer combinations (100 kg P ha^‐1), on maize (Zea mays L.) productivity, P use efficiency (PUE) and farm profitability. The application of biochar with organic–inorganic P fertilizers significantly increased soil P and SOC contents than the sole organic or inorganic P fertilizers. Addition of biochar and PM as 100% P source resulted in the highest soil P (104% increase over control) and SOC contents (203% higher than control). However, maize productivity and PUE were significantly higher under balanced P fertilizer (50% organic + 50% mineral fertilizer) with biochar and the increase was 110%, 94% and 170% than 100%‐FYM, 100%‐PM and 100% mineral fertilizer, respectively. Maize productivity and yield correlated significantly positively with soil P and SOC contents These positive effects were possibly due to the ability of biochar to improve soil properties, P availability from organic–inorganic fertilizers and SOC which resulted in higher PUE and maize productivity. Despite the significant positive relationship of PUE with net economic returns, biochar incorporation with PM and mineral fertilizer combination was economically profitable, whereas FYM along biochar was not profitable due to short duration of the field experiments.     

Long‐term non‐flooded mulching cultivation influences rice productivity and soil organic carbon

A field experiment was conducted for 10 years to examine the long‐term effects of non‐flooded mulching cultivation on rice yield and soil organic carbon on Chengdu Plain, south‐west China. Compared with traditional flooded cultivation (TF), non‐flooded plastic film mulching (PM) resulted in a 14% higher average rice (Oryza sativa L.) yield. However, non‐flooded straw mulching (SM) decreased the average rice yield by 11% compared with TF. After 10 years, PM led to similar or higher (SM) soil organic carbon (SOC) and total soil N (TN) in the top 5 cm of the soil profile compared with TF. No differences were found among the three cultivation systems in SOC or total N at 5–12 and 12–24 cm soil depths. Small macroaggregates (0.25–2 mm) were predominant in the top 5 cm of the soil (58–63% of whole soil) across the three cultivation systems. However, the proportion of large macroaggregates (>2 mm) from SM and PM was significantly larger than from TF in the top 5 cm of the soil. Non‐flooded mulching cultivation led to increased C and N contents in large macroaggregates and mean weight diameter of aggregates in the 0–5 cm soil depth. This suggests that non‐flooded mulching cultivation increased soil aggregation concomitant with soil C stabilization within the improved soil structure.     

长期保护性耕作提高土壤大团聚体含量及团聚体有机碳的作用

【目的】团聚体形成被认为是土壤固碳的最重要机制。本文以河南豫西地区长期耕作试验为研究对象,研究了长期保护性耕作对土壤团聚体性质及土壤有机碳(SOC)含量的影响,为探讨土壤固碳机理,优化黄土高原坡耕地区农田耕作管理措施,实现土壤固碳减排、培肥土壤提供理论依据。【方法】长期耕作试验开始于1999年,试验处理有免耕覆盖(NT)、深松覆盖(SM)和翻耕(CT)。利用湿筛法筛分第3年(2002年)和第13年(2011年)0—10cm和10—20 cm土层中,2000、250~2000、53~250和53μm级别的水稳性团聚体,计算团聚体平均质量直径(MWD),并测定了各级别团聚体的有机碳(SOC)含量。【结果】1)连续13年免耕覆盖和深松覆盖显著提高了土壤表层0—10 cm的SOC含量,分别比翻耕增加了33.47%和44.48%。2011年免耕覆盖和深松覆盖SOC含量较2002年上升了1.92%和8.59%,翻耕下降了18.97%。2)与翻耕相比,免耕覆盖和深松覆盖2000μm团聚体含量显著提高了40.71%和106.75%;53~250μm团聚体含量显著降低了19.72%和22.53%;团聚体平均质量直径显著提高了20.55%和39.68%,显示了土壤结构的明显改善。3)免耕覆盖和深松覆盖显著提高了表层土壤所有团聚体有机碳的含量,尤其以2000μm团聚体提升最多。与翻耕相比,2000μm团聚体有机碳分别提高了40.0%和27.6%。4)免耕覆盖和深松覆盖下表层土壤大团聚体有机碳含量随耕作年限增加,微团聚体有机碳随耕作年限降低。2000μm的土壤团聚体有机碳含量2011年较2002年分别升高了23.93%和7.12%,53~250μm微团聚体有机碳含量分别下降了19.58%和13.27%。【结论】长期保护性耕作(包括免耕覆盖和深松覆盖)可显著提高表层土壤大团聚体含量,降低微团聚体含量,提高团聚体的水稳性,改善土壤结构。同时可增加土壤团聚体有机碳含量,提高土壤肥力。长期保护性耕作在河南豫西丘陵地区是一种较为合理的耕作方式。     

石羊河流域干旱荒漠区人工梭梭林对土壤碳库的影响

采用野外调查与室内分析相结合的方法,研究石羊河流域民勤干旱沙区种植人工梭梭林4,13,36年后的土壤有机碳(Soil organic carbon,SOC)、无机碳(Soil inorganic carbon,SIC)、全氮(Total nitrogen,TN)和总碳(soil total carbon,TC)含量及储量变化特征。结果表明:流动沙地种植梭梭后,0-50cm层灌丛下和行间SOC和TN含量总体随造林年限增加而增加,5-50cm层灌丛下SIC含量在13年梭梭林地最高。36,13年林地0-50cm层灌丛下SOC和TN储量均高于行间,而13年灌丛下SIC储量低于行间,4年灌丛下5-50cm层SOC、TN和SIC储量均低于行间。0-50cm层土壤有机碳、无机碳、全氮储量增幅分别为102.44%,24.66%,54.55%,36年林地SOC和TN储量随土层加深先降低后增加,但4,13年和流动沙地SOC、SIC和TN储量均随土层加深而增加。土壤有机碳占总碳比例随造林年限增加而增加。相关分析结果表明,土壤颗粒组成、造林年限、土层深度等与土壤有机碳和全氮储量显著相关(P0.01)。民勤干旱沙区造林提高了土壤碳库截存量,并且随林龄增长而增长。     

森林转换对土壤活性有机碳组分的影响

为了研究林型转换对土壤活性有机碳组分的影响,在安徽皖南地区蔡家桥林场选取了马尾松次生林、湿地松人工林以及杉木人工林3种森林类型,分别采集了0—10,10—30,30—50 cm的土壤,测定了土壤有机碳(SOC)、颗粒有机碳(POC)、易氧化有机碳(EOC)、微生物生物量碳(MBC)、可溶性有机碳(DOC)以及土壤理化指标,分析了林型转换后土壤活性有机碳组分变化特征及其与土壤理化因子间的相关关系。结果表明：(1)马尾松次生林转换成湿地松人工林和杉木人工林后主要对0—10 cm土壤活性有机碳组分产生影响,其中土壤SOC,POC,EOC含量均在林型转换后出现下降,DOC含量上升,而MBC在林型转换前后无显著差异。(2)林型转换后各土层POC/SOC均出现下降,DOC和EOC占SOC比例总体呈升高趋势,MBC/SOC则未表现出明显规律。(3)土壤有机碳与活性碳组分以及TN,EC,NH⁺₄-N,NO^-₃-N均呈极显著正相关,各活性碳组分之间也存在极显著正相关关系(p<0.01)。综上,马尾松次生林转换成...     

Response of soil properties and C dynamics to land-use change in the west of Loess Plateau

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.     

An appraisal of soil organic C content in Mediterranean agricultural soils

Low soil organic carbon (SOC) levels in dry areas can affect soil functions and may thus indicate soil degradation. This study assesses the significance of SOC content in Mediterranean arable soils based on the analysis of a broad data set of 2613 soils sampled from Mediterranean grasslands and agricultural land. The distribution in values of SOC, pH, clay and carbonates was analysed according to different climatic areas (semi‐arid, Mediterranean temperate, Mediterranean continental and Atlantic) and with respect to six different land uses (grassland, cereal crops, olives and nuts, vineyards, fruit trees and vegetable gardens). The general trend was for low SOC in arable land and decreased with aridity. In wet areas (Atlantic and Mediterranean continental), acidic soils had a higher SOC content than did calcareous soils, whereas in the Mediterranean temperate area SOC had little relationship to soil pH. In low SOC arable soils, the SOC content was related to clay content. In calcareous arable soils of the Mediterranean temperate zone, SOC content was more closely related to carbonates than to clay. In contrast to the Atlantic area, Mediterranean grassland soils had much lower amounts of SOC than forest soils. Mediterranean calcareous and temperate acidic soils under grassland had SOC‐to‐clay ratios similar to or only slightly greater than that under a crop regime. In contrast, Mediterranean continental acidic soils under grassland had a much higher SOC‐to‐clay ratio than arable soils. This suggests a low resilience of the Mediterranean temperate and calcareous arable soils in terms of SOC recovery after the secession of ploughing, which may be a result of intensive use of these soils over many centuries. Consequently, we hypothesize that the Mediterranean calcareous soils have undergone significant changes that are not readily reversed after ploughing ceases. Such changes may be related to alterations in soil aggregation and porosity which, in turn, are associated with soil carbonate dynamics. Decarbonation processes (the depletion of active carbonates) may therefore be relevant to the reclamation of highly calcareous arable soils through fostering soil re‐aggregation. The article concludes by discussing the suitability of zero tillage, manuring or the introduction of woody species to increase SOC in calcareous arable soils that are highly depleted of organic matter.     

稻草还田条件下水田和旱地土壤有机碳矿化特征与差异

采用14C示踪技术,通过100 d的原状土柱室内模拟试验,得出以下研究结果:培养100 d后,有34.74%(水田覆盖)、17.85%(水田翻埋)、35.68%(旱地覆盖)和36.06%(旱地翻埋)的稻草碳被矿化,水田和旱地土壤分别有0.99%～1.17%和2.25%～2.53%的原有有机碳被矿化。土地利用和稻草还田方式及两因素的交互作用,对添加稻草碳的矿化速率和累积矿化率均有显著影响(p<0.01),但对于土壤原有有机碳的矿化速率和累积矿化量,只有土地利用方式对其有显著影响(p<0.01);添加稻草后,土壤总累积矿化量没有发生显著变化(旱地翻埋除外),因为稻草还田抑制了土壤原有有机碳的降解,使100 d的累积矿化量相对于各自对照减少了13.95%(水田覆盖)、15.68%(水田翻埋)、11.04%(旱地覆盖)和3.34%(旱地翻埋)。水田翻埋和旱地覆盖是稻草资源合理利用的较好方式,更有利于土壤有机碳的积累;添加的稻草碳和土壤原有有机碳在水田的矿化速率均显著低于旱地,是水田有机碳含量通常高于同一景观单元旱地的主要原因之一。     

有机物料对红壤团聚体稳定性的影响

试验设置了对照(CK)、秸秆混匀(M-Str)、秸秆覆盖(Str)、生物质炭混匀(BC)和猪粪混匀(SM)5个处理,采用室内培养法研究有机物料种类与施用方式对红壤团聚体稳定性的影响。结果表明,秸秆混匀与猪粪处理下土壤有机碳(SOC)、热水溶性有机碳(HWC)、土壤抗破碎性和团聚体水稳定性(MWD)显著提高(p0.05),而秸秆覆盖对土壤有机碳和土壤团聚体形成的提升作用不明显(p0.05)。相对于对照处理,生物质炭提高了土壤有机碳含量,但对团聚体稳定性的影响不显著(p0.05)。秸秆混匀和猪粪处理下团聚体稳定性的变化与土壤累积呼吸之间存在线性关系(p0.05)。可见,有机物的性质(秸秆、猪粪和生物质炭)与还田方式(混匀和覆盖)对红壤团聚体的稳定性存在显著差异。     

滇中不同植物群落对紫色土表层土壤碳、氮累积的影响

通过连续观测2007-2008年滇中飒马场5种植物群落下紫色土表层土壤理化性质及碳、氮含量的旱雨季变化和层次分布特征,以揭示滇中不同植物群落对紫色土碳、氮累积效应的影响.研究结果表明:植物群落对表层土壤有机碳及其组分、全氮含量、pH及容重有显著的影响.云南松林表层土壤(0-20 cm)有机碳贮存量(24.9 t/ha)显著低于次生常绿阔叶林、桉树林和针阔混交林土壤的.不同植物群落表层土壤(0-20 cm)的全氮贮存量之间没有显著的差异.易氧化有机碳含量的变化是引起各植物群落表层土壤有机碳含量的呈现差异的主要原因.旱雨季变化对各土层易氧化有机碳及总有机碳含量、pH有明显的影响.表层土壤有机碳贮量与地表枯落物碳贮量变化特征之间表现出明显的滞后效应,且二者无显著相关性,表明地表枯落物可能不是影响土壤有机碳碳贮量季节变化的主要因素.     

长期施肥对砂姜黑土可溶性碳淋溶的影响

研究施肥对砂姜黑土可溶性碳淋溶的影响,对有机肥的可持续利用有重要意义.该研究依托33 a的长期试验,分析常规施肥(MF)、化肥+低量小麦秸秆(MFL)、化肥+高量小麦秸秆(MFH)、化肥+猪粪(MFP)和化肥+牛粪(MFC)等施肥方式对土壤剖面(0～60 cm)理化性质、微生物性状、可溶性有机碳(Dissolved O...     

Changes in soil properties after afforestation in Horqin Sandy Land,North China

We studied the changes in soil properties after afforestation on desertification-affected sandy soils to estimate how much time would be required for soils to recover enough for use in sustainable food production. We surveyed soils near and within 3-, 9-, and 19year- old plantations of poplar (Poplus simonii) in the central part of Naiman County, eastern Inner Mongolia, China. Changes in the soil properties following afforestation included an accumulation of fine particles (clay + silt) and soil organic carbon (SOC) in the surface horizons. The contents of fine particles and SOC increased slowly in the first 9-year period and then rapidly between 10 and 19 years, being higher at concave than convex sites. Soil parameters such as available moisture level, amounts of available N and available P, and CEC that control soil fertility showed a similar trend to that of the contents of fine particles and SOC. The contents of fine particles and SOC were higher at the windward edge than in the center of the 19-year-old poplar plantation, suggesting that the accumulation of fine particles was caused by the decrease in wind velocity due to the presence of vegetation. The increase in the SOC content may be caused by the increased carbon input to soils from the vegetation and by the deposition of fine particles with a higher C concentration than that of native sandy soils. Soil fertility, represented by the amounts of available N in the upper 20 cm layer of the soil, recovered after 19 years under poplars, and was similar to that of adjacent fertile cropland. However, the amount of available N under plantations younger than 10 years was lower than that in cropland soils, suggesting that a period of between 10 and 20 years is required for soils to recover from desertified conditions and be utilized for intensive crop farming once again.     

不同有机物料对苏打碱化土有机碳库和化学性质的影响

以内蒙古河套灌区苏打碱化土为研究对象开展田间试验,设置常规施肥(CK)、生物炭+常规施肥(BC)、牛粪+常规施肥(CD)、玉米秸秆+常规施肥(SW)和羊粪+常规施肥(GM)5个处理,研究不同有机物料添加对碱化土壤有机碳(SOC)库和化学性质的影响。分别于2019年和2020年收获季采集0—30 cm耕层土壤,分析不同有机物料添加下SOC及其活性碳组分和主要盐碱指标的变化特征及其相关关系。结果表明:与CK相比,2019年和2020年各有机物料添加处理下SOC平均增幅分别为22.7%和17.2%,土壤有机碳储量(SOCs)平均增幅分别为22.9%和18.2%;4种有机物料均提高了碱化土壤活性有机碳组分含量,其中,CD和GM处理下各活性碳组分含量增幅较其他处理更高;2019年各有机物料添加处理下碳库管理指数(CPMI)较CK提高53.8%~108.3%,2020年提高71.3%~144.1%(P＜0.05),CD和GM对CPMI的提升作用更明显。土壤化学性质方面,2020年各有机物添加处理下pH均显著下降,BC和CD处理下碱化度(ESP)分别显著下降36.9%和29.3%,CD处理下蔗糖酶活性提高36.7%(P＜0.05)。主成分分析(PCA)表明,影响苏打碱化土SOC含量变化的主要因素为活性有机碳组分和ESP。牛粪和羊粪施用对苏打碱化土有机碳库质量提升作用较好,生物炭施用对盐碱化指标改良效果最明显。     

Aggregate-associated soil organic carbon and total nitrogen following amendment of puddled and sawah-managed rice soils in southeastern Nigeria

Puddling during sawah rice cultivation destabilizes the soil structure. The re-formation of soil water-stable aggregates (WSA) following puddling and amendments, and their associated organic carbon (SOC) and total N were studied at Akaeze and Ikwo in south-eastern Nigeria. The amendments, which were randomized in triplicate, include control, NPK fertilizer, poultry dropping, rice husk powder and rice husk ashes (RHA). Soil samples from 0 to 15 cm depth were taken from the field after 2 years of cultivation. Most of the SOC were found in the very fine aggregates. There was no consistent trend in the treatment effects. However, the NPK-amended soils showed the lowest values of WSA > 2 mm in both locations, whereas the poultry dropping-amended soils showed the least and the highest mean-weight diameter (MWD) values at Akaeze and Ikwo, respectively. The SOC of the whole soil in Akaeze correlated positively with MWD (r = 0.92*). Irrespective of location, SOC in soils and WSA > 2.00 mm correlated positively with MWD (r = 0.56*; 0.65*, respectively) while SOC in WSA 0.50–0.25 mm accounted for low MWD values. More carbon was sequestered at Akaeze than at Ikwo, with the RHA-amended soils being the highest at both locations.     

黄土高原丘陵区退耕还林地土壤碳氮库的动态变化(英文)

为了揭示坡耕地退化土壤植被恢复后土壤中碳(C)、氮(N)运移规律,采用植被次生演替空间序列代替时间序列的方法,研究了黄土丘陵沟壑区纸坊沟流域不同植被恢复模式下的C、N库及其相互关系在土壤剖面的时空变化。结果表明退化农地的造林显著地促进了CO2的固存,恢复了土壤N的可获得性,进而降低了N不足对可持续的CO2固存的限制。植被恢复显著地促进了0~60 cm土壤有机碳(soil organic carbon,SOC)和总氮(total nitrogen,TN)的积累,而只有在高于一定的恢复时间阈值(如26 a)下,促进了SOC库和TN库间的线性相关性。在土壤剖面上,SOC和TN库、SOC/TN库比以及SOC-TN间的线性相关性均随着土壤深度的增加而降低。与自然恢复相比,人工林在短期内具有CO2固存的优势,但由于随着恢复时间的增加,SOC增幅越来越大于TN增幅的事实,表明造林对碳固存的可持续性需在一个较长的时段下来评估,尤其需要关注20 cm以下层土壤。研究结果为黄土高原的生态修复和减缓温室效应提供了理论依据。     

不同有机物料还田对华北农田土壤固碳的影响及原因分析

中国农业面临着废弃物数量大、污染严重,农田土壤生产力低的现实问题。该研究以增加农田土壤固碳为目标对砂质农田进行有机物料还田,将秸秆、猪粪、沼渣和生物炭4种物料用尿素调节等氮还田,对农田土壤有机碳、颗粒有机碳、可溶性有机碳和微生物量碳的含量进行测定,并探究不同有机物料还田对土壤有机碳的影响原因。研究结果表明:物料还田3a后,生物炭、猪粪和沼渣处理土壤有机碳(SOC)比秸秆处理分别高262.4%、26.8%和20.7%;2014—2015年生物炭处理的土壤微生物量碳(MBC)较秸秆处理降低2.9%~35.5%,猪粪处理和沼渣处理的土壤可溶性有机碳(DOC)分别提高17.1%~60.1%和7.2%~64.8%;2014—2015年生物炭、猪粪和沼渣处理土壤颗粒有机碳(POC)较秸秆处理提高10.8%~148.2%、9.5%~58.3%和11.3%~57.6%;物料还田后,土壤总有机碳(TOC)和POC呈极显著的回归关系(R2=0.67,P0.001),土壤DOC与MBC有极显著相关性(R2=0.52,P0.001)。与秸秆还田相比,生物炭还田有利于土壤POC的累积进而促进土壤有机碳的提升,猪粪和沼渣则通过提高土壤MBC、DOC和POC的含量,促进土壤有机碳的周转和固定。从农田土壤固碳角度而言,生物炭,猪粪和沼渣还田优于秸秆还田。