Soil Organic Matter Content and Quality in Polyfactorial Field Experiments

The polyfactorial long-term field experiments founded in 1979 exist in four different sites till the present time. The experimental design and selected variants have been described in our previous paper (Lipavsky et al. 2002). Besides of the organic carbon and nitrogen contents in soil, dry matter of the main and second products, nitrogen uptake by the main and second products presented in our previous paper (Lipavsky et al, 2002), hot water soluble carbon (C hwl ), humic substances, e.g. humic and fulvic acids have been determined in soil samples taken in autumn each year from six selected variants of organic and mineral fertilisation. The results of the hot water soluble carbon content and humic and fulvic acids contents in the air dried soil samples have been evaluated in this paper. It was shown that humic substances are rather conservative and site specific soil properties that are not much affected by the cropping and fertilisation systems. Hot water soluble carbon, on the other hand, seems to be a dynamic part of the soil organic matter.     

Importance of Soil Organic Matter (SOM) for Biomass Production and Environment (a review)

The aim of sustainable agricultural land use is to reach high and rising crop yields and to minimise environmental pollution. Soil organic matter (SOM) plays a key role in maintaining soil productivity and also in protection of environment. At least two SOM fractions can be distinguished, one being relatively inert, the other being decomposable. High yields are only attainable on an environmentally acceptable way in combination of organic and mineral fertilization. The ranges for the optimal content of the decomposable organic carbon is between 0.2 and 0.6% and that of nitrogen 0.02 and 0.06%. The hot water extractable carbon has proved to be an appropriate criterion for the characterisation of the decomposable carbon. When considering the current state of knowledge consistently, the use of mineral fertiliser has a positive effect on the environment and supports a considerable gain of energy by the cultivated crops. Too high humus content in soil can contribute to environmental pollution. Between organic carbon content and soil physical properties there is nearly functional relation.     

长期施肥对西南黄壤碳氮磷生态化学计量学特征的影响

为了解长期不同施肥措施下黄壤碳、氮、磷生态化学计量学特征,研究以贵州黄壤长期定位试验2003~2013共11年土样为研究对象,测定分析土壤碳、氮、磷养分及生态化学计量指标变化特征,旨为黄壤培肥、增加土壤碳汇提供重要理论依据。结果表明:(1)长期不同施肥措施下,有机碳、全氮、全磷含量变化较一致,均以有机肥处理较高,且随有机肥施用量增加而增加;(2)不同处理土壤C/N、C/P、N/P比变化范围为13.49~15.58、13.72~17.86、0.99~1.28,通过各处理变异系数和碳、氮、磷两两相关分析可知,黄壤C/N比较稳定,碳氮变化一致,而C/P、N/P比变化较大;(3)C/N、C/P比与有机碳呈极显著正相关关系,N/P比与全氮呈极显著正相关关系,但相关系数各不同;(4)与中国和世界土壤C/N/P比平均水平相比,黄壤碳、氮、磷比例失衡。     

Potential for Optimisation of Carbon and Nitrogen Dynamics on Black Earth in Central Germany- and N-Turnover

This paper reports results from investigations of carbon turnover and the dynamics of carbon and nitrogen in an area with high intensity farming in the black earth region of Central Germany. The long term experiments situated in Bad Lauchstädt provide valuable information about interaction of carbon storage and the efficiency of nitrogen use by the growing crops. Starting from the hypothesis that a sustainable agriculture is bound to make maximum use of diffuse nitrogen inputs from atmosphere, which is estimated to be about 60kg N/ha/a in Bad Lauchstädt, the potentials to control the utilisation of this nitrogen flux will be discussed. A possible benchmark for an environmental sound agricultural system is a N surplus at least lower as N input from atmosphere or better lower than 40kg/ha in order to meet the requierements of water protection. The possibilities for agricultural systems to add nitrogen with organic matter or with mineral fertiliser will be discussed.     

长期三熟制下谷物产量和土壤氮磷钾及有机质性状的演化

自1973年10月起在麦稻稻三熟制下连续进行了26年定位试验。结果表明,长期配施N肥和猪厩肥可以实现谷物的持续增产,保持土壤有机质的持续增长,并培肥土壤,有机质达到60g/kg的高水平。稻田土壤的有机质数量演化可以幂指数方程表示。土壤N素平衡有余,全N大幅度增加,而有效N的增长差距巨大。全K和速效K显著下降,缓效K变化不大。全P在平衡或盈余时有效P大幅提高。     

Relations Between Net Nitrogen Mineralization and Soil Characteristics Within an Arable Field

Within-field variations in plant-available soil nitrogen (N) are likely to be affected by differences in soil characteristics. To study this, a 3- year field investigation was conducted during 1998-2000 on a 15 ha arable field in Sweden with considerable within-field soil texture variability. In 34 plots soil N uptake by crops, net nitrogen mineralization (Nm) during the growing season and soil mineral N in spring and shortly after harvest were determined. Beside these parameters, topography, soil organic matter content (SOM), clay content, pH(H 2 O) and grain yield were recorded. The variations in Nm were considerably large both within the field and between years. The within-field variation in Nm could partly be explained by the variation in SOM and clay content (adjusted coefficient of determination = 0.23, P <0.001). The pattern in Nm differed between years, partly because of seasonal variations in soil moisture. For these reasons, the pattern of Nm is difficult to predict without seasonal adjustments.     

基于SOTER的河北省土壤有机碳、氮密度的空间分布

本文在河北省土壤与地形体数据库基础上,计算了该省不同土壤组合的土壤有机碳和氮的密度,应用GIS技术分析了河北省土壤有机碳和氮密度的空间分布特征。结果表明:河北省土壤的平均有机碳密度为10.83kgm-3,平均氮密度为1070.96gm-3,C/N比为9.99;该省的土壤有机碳和氮密度的空间分布均呈现:不同类型土壤组合的有机碳和氮密度均随着纬度的增加而逐渐增加,而且其分布受气候、土壤特性、土地利用方式、植被特性以及人类干扰程度等的影响。     

Soil Organic C Development in Cereal and Ley Systems. Data from 20 Years Old Swedish Field Experiments

In four Swedish long-term field experiments in cereals and in four with mixed ley production the top soil organic C changes with time were investigated at different N levels. In the cereals treatments with all straw removed and all straw chopped and ploughed into the soil were compared. The experiments were started 20 years or more ago at 4 contrasting sites from south to north and they are still running. In the cereal system the C content decreased from 2.3 to 1.9% on average over the sites. The decline was the biggest where the initial content was the highest. Straw returned increased the C content with 0.1 percentage unit compared with straw removed. N also increased the C content in the cereal system but not in the ley system. The change with time was also insignificant in the ley part. Estimated rate constants for C decomposition varied from 0.1 to 1.66% yr m 1 in cereals. It decreased usually with increasing N level. When straw was returned at the high N level the rate constant also decreased. The rate constants corresponded to C break down of 610-740kg ha m 1 at the northernmost site and 250-270kg ha m 1 at the southernmost. With the assumed humification factor of 15% the gross supply of C was not high enough to maintain present C content at the northern site but at the southern site it was. In the ley systems steady state levels seemed almost to be established.     

不同供氮水平对玉米秸秆降解初期碳素矿化及微生物量的影响

采用室内恒温(25℃)培养方法研究了不同无机态氮供应水平(0、30、60、80、100Nmgkg-1土)对玉米秸秆降解初期的影响。试验结果表明:碳素的矿化量随着添加无机氮源数量的增加而增加,其中两个高氮添加量(80、100mgkg-1)处理的碳素矿化量要高于不加氮源和两个低氮添加量处理(30、60mgkg-1)。不同氮量添加条件下微生物量碳的变化呈相同趋势。利用土壤呼吸和微生物量碳计算而得的微生物代谢商在低量氮素处理条件下高于较高量氮源添加处理,表明高量氮素添加可提高微生物对秸秆碳素的利用效率。以上结果说明:对C/N比较大的玉米秸秆而言,土壤中无机氮素的供给对残体碳素的初始矿化有明显的影响,相对较低的氮源供给量不能满足微生物快速生长代谢对氮素的需求,使秸秆降解过程受到一定程度的抑制,不利于土壤氮素截获。因此在大田条件下,秸秆还田时要考虑氮素的供应问题,根据实际需要确定秸秆还田时间及肥料氮素施用水平。     

土壤溶解性有机碳(DOC)的影响因子及生态效应

土壤溶解性有机碳(DOC)是陆地生态系统中极为活跃的有机组分,是土壤圈层与相关圈层(如生物圈、大气圈、水圈和岩石圈等)发生物质交换的重要形式。影响土壤中物质的溶解、吸附、解吸、吸收、迁移乃至生物毒性等行为之外,对温室气体CH4的排放、水体水质的污染、岩石圈的风化等的影响也不可忽视。本文以陆地生态系统的中的DOC为主体,探讨了DOC的生态环境意义及其对大气、水体和岩石圈的影响以及DOC对土壤管理措施的响应。     

Synergy Between Fertilizer and Irrigation Water for Higher Resource Use Efficiency in Field Crops

Field experiments conducted under different levels of irrigation and fertilizers reveal that water and fertilizers increased each others' efficiency in several field crops. However, the over dose of fertilizers in the absence of adequate watering or nutrients deficiency under frequent watering had adverse effects on crop productivity. These effects were mediated through plant water status and related physiological processes. Thus, a proper combination of irrigation water and fertilizers is required for attaining high water and fertilizers use efficiency in field crops.     

氮磷输入对湿地生态系统碳蓄积的影响

湿地生态系统在全球碳循环中有着举足轻重的作用。由于湿地垦殖、农业化施用等人类活动和全球变暖、大气氮沉降的增多等自然因素的综合作用,大量氮磷营养物质进入湿地,这必将对湿地生态系统碳蓄积产生影响。本文综述了外源氮磷输入对湿地土壤碳库、植被碳库和枯落物分解的影响以及湿地生态系统碳循环的模型研究,并对以后发展趋势进行了预测。     

黑碳在土壤有机碳生物地球化学循环中的作用

黑碳是化石燃料或生物有机体不完全燃烧形成的一种含有芳香环的高聚物,碳元素含量在60%以上,另含有氢、氧、氮、硫等元素。新近的研究证实,黑碳通过在缓慢的土壤有机碳库中的循环,对全球碳和氧的地球生物化学循环起到极其重要的作用。本文对黑碳的基本概念、理化性质、在土壤中的作用及测定方法进行了综合评述,提出了开展土壤黑碳研究的重要性和必要性。以期为我国开展土壤黑碳的相关研究提供理论参考。     

减氮配施有机肥对夏玉米——冬小麦土壤硝态氮及氮肥利用的影响

为实现华北平原夏玉米-冬小麦的高产及氮肥的高效利用,采用田间小区试验方法,研究了氮肥减量及其与有机肥配施对夏玉米-冬小麦轮作体系内土壤硝态氮分布及氮肥利用的影响。结果表明:与不施氮处理(CK)相比,施用氮肥增加了冬小麦和夏玉米的生物量和产量,而在农民习惯施氮基础上减量1/3不会显著影响到生物量和产量。其中减氮配施有机肥(ONM)处理的周年总产最高,相比习惯施氮(CN)和减氮处理(ON)分别提高了1.85%和3.78%。处理CN的0~180 cm土壤硝态氮累积量的周年变化均值达502.7 kg hm^-2,分别是处理CK、ONM、ON的2.95、2.17、1.56倍。与处理CN相比,处理ONM显著降低了剖面(0~180 cm)土壤中的硝态氮含量,其中在夏玉米季和冬小麦季的降低幅度分别为18.1%~66.7%和37.3%~87.2%。处理ON和ONM相比处理CN,植株周年总吸氮量无显著性差异,氮肥利用率却得到了显著提高。其中处理ONM的周年氮肥利用最高,比处理CN提高了36.9%。综合分析,减氮与有机肥配施不仅显著降低了0~180 cm土壤硝态氮含量,大幅度提高了氮肥利用率,且有助于增加冬小麦和夏玉米的生物量及产量。     

喀斯特石漠化综合治理区表层土壤有机碳密度特征及区域差异

以中国南方喀斯特地区具有代表性的贵州为例,选取3个典型喀斯特石漠化综合治理示范区,以划分出的4条核心小流域为监测单元,对各示范区内及示范区之间不同等级石漠化样地表层土壤有机碳密度特征进行比较。结果表明:各示范区之间表层土壤有机碳密度变异性较大,表现为红枫湖示范区(6.12 kg m-2)>鸭池示范区(5.21 kg m-2)>花江示范区(2.80 kg m-2);不同等级石漠化样地之间土壤有机碳密度整体表现为无明显、潜在石漠化样地大于中、强度石漠化样地;岩石裸露率是影响喀斯特地区表层土壤碳密度的重要影响因子之一,特别对于中、强度石漠化区;地貌、气温和不同工程措施也在一定程度上影响到土壤有机碳密度特征。喀斯特石漠化综合治理具备巨大的固碳减排效应,采取有效措施增加有机碳蓄积量是今后石漠化综合治理的关键。     

生物炭施用对稻田氮磷肥流失的影响

针对宁夏引黄灌区稻田过量施肥导致土壤养分利用效率低的问题,通过田间小区试验,在优化施氮条件下(240kg·hm~(-2)),设4个生物炭水平(0、4500、9000、13500kg·hm~(-2)),研究施用外源生物炭对稻田氮磷流失和土壤养分含量的影响。结果表明:生物炭对稻田田面水氮素动态产生影响,表现为田面水中全氮、硝态氮含量随生物炭用量的增加而降低,铵态氮表现则相反;全氮和铵态氮的最大峰值出现在第1次追施氮肥后的第2天,最大值为34.86、8.28mg·L~(-1);硝态氮最大峰值3.31mg·L~(-1)出现在第2次追施氮肥后的第2天。随后均迅速下降,全氮含量在施氮肥后10d回到第1次追氮前的含量水平,并趋于稳定,铵态氮和硝态氮则在7d后。生物炭对田面水全磷未产生显著影响,全磷含量在第1次施氮肥后3d达到峰值,为3.69mg·L~(-1),之后迅速下降,6~7d后降至追氮前的含量水平,并趋于稳定。生物炭处理显著降低了稻田全氮流失量8.03%~13.36%,高量炭处理(13500kg·hm~(-2))显著提高了土壤全氮和有机质含量,提高幅度分别为41.2%和27.5%(P0.05)。说明生物炭对稻田磷流失、土壤全磷和速效磷含量无显著影响,对降低稻田氮素淋失表现出积极效果。     

Nematode faunal response to long-term application of nitrogen fertilizer and organic manure in Northeast China

Nematode faunal response to the long-term (20-year) application of nitrogen fertilizer and organic manure was monitored in a Hapli-Udic Cambosol of Northeast China, where no fertilizer (C), nitrogen fertilizer (N), organic manure (M) and nitrogen fertilizer plus organic manure (N + M) treatments were compared. The obtained results showed that total nematode abundance responded positively to the M and N + M treatments. The numbers of Acrobeloides increased in the M and N + M treatments at maize jointing and booting stages, and those of Aphelenchoides were higher in the N + M treatment than in the N treatment at maize ripening stage. Early in the growing season, the numbers of bacterivores of cp-1 (cp, colonizer-persister) and cp-2 guilds were higher in the M and N + M treatments than in the N treatment, while those of bacterivores and fungivores of cp-4 guilds were higher in the C treatment than in the N, M and N + M treatments. Except at maize seedling stage, the numbers of fungivores of cp-2 and herbivores of cp-3 guilds were higher in the N + M treatment than in the C treatment. Ratios of the weighted abundance of representatives of specific functional guilds were used as indicators of food web structure, enrichment and decomposition channels. Values of the enrichment index (EI) at maize seedling and jointing stages were higher in the M and N + M treatments than in the C and N treatments, while an opposite trend was observed in the channel index (CI). Higher EI and lower CI suggest an enriched soil food web dominated with bacterial decomposition channels in the M and N + M treatments.     

耕作对旱区坡耕地土壤碳素转化及冬小麦产量的影响

利用长期定位试验(1999开始保护性耕作,2004年采样测定),在豫西旱区坡耕地上进行了不同耕作对土壤有机碳、微生物态碳及水分利用效率的影响研究。结果表明:深松覆盖和免耕覆盖处理的耕层有机碳增加较明显,以深松覆盖有机碳含量最高为6.79gkg-1,比传统耕作高13.82%,其次是免耕,较传统高11.58%,而少耕却较传统降低了1.38%,随着土层的加深,土壤有机碳含量降低,0～60cm有机碳平均值,深松和免耕较传统分别增加了14.08%、5.41%,少耕较传统减少1.12%。土壤微生物碳对耕作敏感,其含量免耕>深松>传统>少耕,分别为206.87mgkg-1、138.43mgkg-1、115.42mgkg-1和112.57mgkg-1,较传统增加79.3%、19.9%和-2.5%。土壤有机碳和土壤微生物态碳都有坡下富集现象。少耕、免耕、深松和传统的SMBC/SOC的值分别为1.91%、3.11%、2.04%和1.93%,免耕和深松对培肥地力、改善环境有好的应用前景;同时免耕覆盖与深松覆盖可提高产量,增产分别达10.22%与9.26%;可提高水分利用效率。