Nitrous Oxide and Carbon Dioxide Emissions from Vietnamese Soil Amended with Different Compost Types at High Temperature

This study aims to determine the effects of compost additions and high temperature on N₂O and CO₂ emissions from a Vietnamese agricultural soil. Soil samples amended with two compost types (commercial compost, SH and chicken compost, CC) at three rates of 1%, 2% and 4% w/w were aerobically incubated at 25°C, 30°C and 35°C for 28 days in the laboratory. N₂O and CO₂ emissions were determined on days 1, 3, 5, 7, 14, 21 and 28. Our results showed that N₂O and CO₂ emissions were significantly affected by temperature, compost additions, and their interactions. Greater N₂O and CO₂ emissions were seen in CC treatments than SH treatments. Higher application rates of CC led to greater N₂O and CO₂ emissions. In SH treatments, higher temperature lowered N₂O emissions but did not affect CO₂ emissions. N₂O and CO₂ emissions were enhanced with CC addition while they showed different responses to increasing temperature.     

Influence of storage and drying methods on invertebrate elemental and isotopic measurements

Optimised pre-analytical methods for measuring the chemical properties of soil macro-organisms are needed. We tested the effects of ethanol immersion, freezer storage, and drying method on the reliability of estimates of key stoichiometric elements (carbon [C], nitrogen [N], phosphorus [P]) and abundances of ¹³C and ¹⁵N in samples of crickets (Acheta domestica), cockroaches (Nauphoeta cinerea) and mealworms (larval Tenebrio molitor). Ethanol immersion tended to increase A. domestica C and N, and reduced A. domestica P, relative to the reference treatment (deep freezing and oven drying). For N and P these effects were only present after 28-day ethanol immersion. Nauphoeta cinerea and T. molitor samples were generally unaffected by storage treatments, while δ¹³C and δ¹⁵N were not affected by any storage treatment for any species. Thus, five days of ethanol immersion may be acceptable prior to elemental and stoichiometric analyses of hard-bodied soil invertebrates in comparative studies.     

Root development of winter wheat in erosion‐affected soils depending on the position in a hummocky ground moraine soil landscape

Agricultural soil landscapes of hummocky ground moraines are characterized by 3D spatial patterns of soil types that result from profile modifications due to the combined effect of water and tillage erosion. We hypothesize that crops reflect such soil landscape patterns by increased or reduced plant and root growth. Root development may depend on the thickness and vertical sequence of soil horizons as well as on the structural development state of these horizons at different landscape positions. The hypotheses were tested using field data of the root density (RD) and the root lengths (RL) of winter wheat using the minirhizotron technique. We compared data from plots at the CarboZALF‐D site (NE Germany) that are representing a non‐eroded reference soil profile (Albic Luvisol) at a plateau position, a strongly eroded profile at steep slope (Calcaric Regosol), and a depositional profile at the footslope (Anocolluvic Regosol). At each of these plots, three Plexiglas access tubes were installed down to approx. 1.5 m soil depth. Root measurements were carried out during the growing season of winter wheat (September 2014–August 2015) on six dates. The root length density (RLD) and the root biomass density were derived from RD values assuming a mean specific root length of 100 m g^?1. Values of RD and RLD were highest for the Anocolluvic Regosol and lowest for the Calcaric Regosol. The maximum root penetration depth was lower in the Anocolluvic Regosol because of a relatively high and fluctuating water table at this landscape position. Results revealed positive relations between below‐ground (root) and above‐ground crop parameters (i.e., leaf area index, plant height, biomass, and yield) for the three soil types. Observed root densities and root lengths in soils at the three landscape positions corroborated the hypothesis that the root system was reflecting erosion‐induced soil profile modifications. Soil landscape position dependent root growth should be considered when attempting to quantify landscape scale water and element balances as well as agricultural productivity.     

纳板河自然保护区土壤酶对不同海拔、坡向的响应

在纳板河自然保护区内分海拔和坡向采集土样,测定分析了尿酶、蛋白酶、蔗糖酶、过氧化氢酶4种主要土壤酶活性和主要养分指标的变化。结果表明:土壤有机质、水解氮含量随海拔升高显著增加;阳坡全氮含量随海拔升高呈现由中间向两端减小的趋势,阴坡全氮含量随海拔升高波动增加;土壤速效磷含量随海拔呈现由中间向两端减小趋势;蛋白酶活性高海拔 > 低海拔,海拔对表层过氧化氢酶活性影响较小,脲酶、蔗糖酶活性随海拔呈现波动。土壤有机质、全氮、水解氮、速效磷含量阳坡 > 阴坡;土壤蛋白酶、过氧化氢酶、蔗糖酶活性阴坡 > 阳坡,各土层土壤脲酶活性阳坡 > 阴坡。各养分含量及酶活性表层 > 中下层。土壤酶活性与各肥力因子间相关关系显著,各土壤酶活性间相关性显著。有机质、全氮、全磷是影响蛋白酶活性的主导因子,速效磷和水解氮为次要因子;全磷、速效磷、水解氮为影响脲酶活性的主要因子,有机质、全磷、速效钾为次要因子。主成分分析结果表明蛋白酶和脲酶活性作为保护区土壤肥力指标具有可行性。     

黄土区不同植被类型条件下土壤分离速率变化特征及其影响因素

为比较土壤理化性质与根系特征对土壤分离速率的影响强度,采用模拟冲刷试验与室内分析相结合的方法,探究了黄土区不同植被类型在3种处理下（含根系、含冠层、含结皮）土壤分离速率变化特征及其影响因素。结果显示:（1）不同植被类型间,狼牙刺群落下土壤分离速率最小,显著低于达乌里胡枝子;不同处理下,含结皮土壤分离速率最大,含根系土壤次之,含冠层土壤最小。（2）土壤分离速率与容重呈显著正相关关系（p<0.05）,与有机质、团聚体呈显著负相关关系（p<0.05）。只考虑土壤理化性质对土壤分离速率的影响时,影响狼牙刺、白羊草群落下土壤分离速率的主导因素是容重;影响铁杆蒿、达乌里胡枝子群落下土壤分离速率的主导因素为有机质。（3）根系特征也是影响土壤分离速率的因素,土壤分离速率与根系生物量密度、根长密度、根系表面积密度、根体积密度呈负相关关系。只考虑根系特征对土壤分离速率的影响时,影响狼牙刺、铁杆蒿、白羊草群落下土壤分离速率的主导因素是根长密度;影响达乌里胡枝子群落下土壤分离速率的主导因素是根系表面积密度。（4）本研究中,土壤分离速率回归方程D_r=0.086-0.035X₁+1.367X₂,（R²=0.767,N=36,p=0.000;X₁为土壤有机质,X₂为土壤容重）,土壤理化性质对于分离速率的作用强于根系的作用;不考虑植被类型时,土壤有机质、土壤容重是影响土壤分离速率的主导因素。     

太行山南麓5个林龄侧柏人工林土壤酶活性季节变化

采用时空互代法,以太行山南麓地区20,30,40,50,60年生侧柏人工林土壤为研究对象,研究了土壤蔗糖酶和脲酶活性的季节变化、空间分布特征及其与土壤因子的相关性。结果表明:土壤酶活性有明显的季节变化特征,土壤蔗糖酶的活性呈夏季 > 秋季 > 春季 > 冬季,脲酶活性的季节动态呈夏季 > 春季 > 秋季 > 冬季,两种土壤酶活性均在夏季最高,冬季最低。土壤蔗糖酶和脲酶活性均随土层深度的增加而显著降低（p<0.01）,从表层0-10 cm至深层30-40 cm酶活性下降幅度均超过46%。相关性分析表明,土壤蔗糖酶和脲酶均与土壤含水率、DOC含量呈极显著正相关关系,且两者之间也存在极显著正相关关系（p<0.01）,但是二者的主要影响因子并不完全一致。逐步回归分析表明蔗糖酶活性的主要影响因子是土壤含水率和砂粒体积分数,二者能解释71.2%的变化;脲酶活性的主要影响因子是DON、土壤含水率、硝态氮含量和土壤容重,四者能解释71.5%的变化,暗示温度和水分可能是该区人工林土壤生物活性的主要控制性因素。     

油枯对镉污染土壤的钝化研究

为了研究油枯对镉(Cd)污染土壤的钝化效果,以油枯为外源添加物(质量比:1%、2%、3%、4%、5%),模拟田间条件在塑料桶中进行为期45 d的培养,对镉污染土壤中Cd形态分布特征、DTPA提取态Cd(DTPA-Cd)含量、pH、有机质含量进行分析。结果表明,添加油枯可显著降低镉污染土壤中可交换态镉(Ex-Cd)的比例,提高碳酸盐结合态镉(Cb-Cd)、铁锰氧化物结合态镉(Fe-Mnb-Cd)以及有机质及硫化物晶格态镉(OMb-Cd)的比例,而残渣晶格结合态镉(RLb-Cd)变化不明显。添加油枯显著降低镉污染土壤中DTPA-Cd含量,降幅最高可达49%。镉污染土壤p H值维持在6.0左右,1%~4%添加处理中土壤pH波动幅度较大;而5%添加处理的土壤pH波动幅度小。添加油枯均能显著提高镉污染土壤中有机质含量。由此可见,油枯对镉污染土壤有较好的钝化效果,这为重金属污染土壤的修复和农业废弃物的循环利用提供了参考。     

广元植烟土壤有效态微量元素的空间变异特征及影响因素

为揭示广元植烟区土壤有效态微量元素含量空间变异特征及影响因素,采用地统计学、相关分析及回归分析等研究方法,结合地理信息系统(GIS)技术对研究区土壤有效铁、锰、铜、锌钼及硼等6种土壤有效态微量元素进行分析。结果表明,研究区土壤有效铁、锰及铜含量丰富,总体处于中等以上水平;有效钼含量适中;有效锌和硼缺乏,总体处于缺乏或极度缺乏水平。半方差分析表明,6种土壤有效态微量元素块金系数均在29.72%~67.59%之间,具有中等强度的空间自相关性,其空间变异受结构性因素和随机性因素共同影响。空间分布上,土壤有效铁、锰、铜及钼含量表现出北高南低的空间分布趋势,土壤有效锌和硼含量呈现出西高东低的空间分布格局。影响因素分析表明,6种土壤有效态微量元素与土壤有机质呈正相关,与p H值呈负相关,相关性总体高于地形因子。土壤有机质对有效铁、铜、锌及硼有极显著影响,其空间变异性为5.5%~27.2%。除有效锌外,土壤p H值对其余5种土壤有效态微量元素含量空间变异均有极显著影响,其空间变异性为5.0%~30.4%。土类对土壤有效铁、锰及铜有极显著影响,其空间变异性8.4%~12.3%。熟制和种植制度对6种土壤有效态微量元素含量空间变异的影响较弱,进一步说明研究区土壤有效态微量元素含量空间变异受结构性因素和随机性因素共同影响,但结构性因素的作用强于随机性因素。本研究结果为广元植烟区土壤微肥施肥管理及优质烤烟栽培提供了可靠的参考依据。     

草海上游石漠化过程中土壤抗蚀性变化

以草海流域上游的石漠化区为研究对象,研究不同等级石漠化条件下土壤抗蚀能力的差异,利用空间代替时间的方法,探讨草海上游区石漠化过程中土壤抗蚀性变化规律,为当地石漠化治理和湿地保护提供参考。通过实地调研,采集不同石漠化程度区的土样并进行室内指标测定,利用主成分分析方法选取了10个土壤理化指标对样地土壤抗蚀能力进行评价。结果表明:(1)所选10项理化指标可以较为全面地综合评价不同石漠化程度土壤抗蚀能力,土壤团聚状况、分散率、分散系数、0.25mm水稳性团聚体含量、0.5mm水稳性团聚体含量、结构破坏率、0.05mm粉黏粒含量这7项可以作为评价的优选指标,有机质含量、0.001mm黏粒含量、土壤团聚度这3项指标次之。(2)无石漠化CK样地(2.19)轻度石漠化L样地(1.19)重度石漠化S1样地(0.85)中度石漠化M样地(-1.35)重度石漠化S2样地(-2.88),其中中度石漠化样地(M)和重度石漠化样地(S_2)为负值,其余均为正值,差异明显。在石漠化过程中土壤抗蚀能力总体呈下降趋势,但是在石漠化发展后期,土壤抗蚀能力反而会有上升的可能。     

草原工程侵蚀区植被恢复模式的水土保持效应

以内蒙古草原大型露天煤矿开采形成的人工再塑地貌为研究对象,针对水土流失特点,结合自然气候、立地条件等因素,以快速恢复工程侵蚀区受损植被、减少水土流失为目的,通过水土保持措施组合配置试验,研究草原工程侵蚀区人工再塑地貌不同植被恢复模式的水土保持效应。结果表明:人工再塑地貌平台植被恢复采用“栽植灌木+种草”的措施配置灌木保存率为85.4%,草本植物盖度76%,土壤风蚀量比其他样区减少30%~85%;边坡植被恢复采用“栽植灌木+种草”模式和“生物笆+灌木”模式植物盖度达60%以上,抗蚀保土能力较强;通过秩和比法进行综合效益评价,“生态袋+种草”和“栽植灌木+种草”两种模式在治理投资成本与水土保持效益方面结合较好,水土流失防控效果明显,可在草原工程侵蚀区人工再塑地貌边坡水土流失治理中优先应用。