Changing sink and source relations in rice (Oryza sativa L.) using carbon dioxide enrichment in the field

Rice plants in the field were enclosed in chambers covered with mylar film and subjected to CO² enrichment for 30 days before or after flowering. The CO² enrichment was intended to increase grain number (sink size) befiore flowering, and to increase photosynthesis of a canopy (source) after flowering.

The CO² enrichment before flowering increased grain number per unit land area and grain weight. The enrichment after flowering did not affect grain number but increased filled-grain percentage and grain weight. As a result, both treatments increased grain yield. Analysis of yield components indicates that a major factor responsible for the yield differences is grain number. It was also shown that the increase in yield was directly proportional to the dry matter increase after panicle initiation.

The CO² enrichment before flowering increased grain number per unit land area and grain weight. The enrichment after flowering did not affect grain number but increased filled-grain percentage and grain weight. As a result, both treatments increased grain yield. Analysis of yield components indicates that a major factor responsible for the yield differences is grain number. It was also shown that the increase in yield was directly proportional to the dry matter increase after panicle initiation.     

两种培肥措施对黑钙土有机无机复合体腐殖质组成的影响

采用Kumada法研究了两种培肥措施对黑钙土及其复合体腐殖质组成的影响。结果表明,在根茬还田的基础上增施有机肥,可使全土及各级复合体的游离态和结合态腐殖质的胡敏酸、富里酸含量及△logK等不同程度地增大,PQ和RF值减小．腐殖化度降低,这种作用在粉粒复合体中表现最为明显。粘粒和粉粒复合体的游离态胡敏酸均为A或B型,细砂均为Rp型。随复合体粒径的增大,游离态胡敏酸类型的变化序列为A型(粘粒)→A型(粉粒)→Rp型(细砂);结合态胡敏酸大多为A型,少数为P或B型。黑钙土增施有机肥培肥后,腐殖质的腐殖化度会发生量变和型变。在黑钙土中,胡敏酸的型变,主要表现在全土和粉粒复合体的游离态腐殖质中。     

Repeated monitoring of organic carbon stocks after eight years reveals carbon losses from intensively managed agricultural soils in Western Germany

Past land‐use changes, intensive cropping with large proportions of root crops, and preferred use of mineral fertilizer have been made responsible for proceeding losses of soil organic C (SOC) in the plough layer. We hypothesized that in intensive agriculturally managed regions changes in SOC stocks would be detectable within a decade. To test this hypothesis, we tracked the temporal development of the concentrations and stocks of SOC in 268 arable sites, sampled by horizon down to 60 cm in the Cologne‐Bonn region, W Germany, in 2005 and in 2013. We then related these changes to soil management data and humus balances obtained from farmers' surveys. As we expected that changes in SOC concentrations might at least in part be minor, we fractionated soils from 38 representative sites according to particle size in order to obtain C pools of different stability. We found that SOC concentrations had increased significantly in the topsoil (from 9.4 g kg^?1 in 2005 to 9.8 g kg^?1 in 2013), but had decreased significantly in the subsoil (from 4.1 g kg^?1 in 2005 to 3.5 g kg^?­1 in 2013). Intriguingly, these changes were due to changes in mineral‐bound SOC rather than to changes in sand‐sized organic matter pools. As bulk density decreased, the overall SOC stocks in the upper 60 cm exhibited a SOC loss of nearly 0.6 t C (ha · y)^?1 after correction by the equivalent soil mass method. This loss was most pronounced for sandy soils [?0.73 t SOC (ha · y)^?1], and less pronounced for loamy soils [?0.64 t SOC (ha · y)^?1]; silty soils revealed the smallest reduction in SOC [?0.3 t SOC (ha · y)^?1]. Losses of SOC occurred even with the overall humus balances having increased positively from about 20 kg C (ha · y)^?1 (2003–2005) to about 133 kg C (ha · y)^?1 (2005–2013) due to an improved organic fertilization and intercropping. We conclude that current management may fail to raise overall SOC stocks. In our study area SOC stocks even continued to decline, despite humus conservation practice, likely because past land use conversions (before 2005) still affect SOC dynamics.     

Organische Bodensubstanz und Bodenzönose — Qualitäten,Korrelationen und Wechselbeziehungen — Einführung in das Symposium

Dead organic matter and soil biota — qualities, correlations and interrelationships At the biannual meeting of the German Soil Science Society at Konstanz, September 7 to 12, 1997, a symposium was held to summarize actual research on the quality of soil dead organic matter and its interrelations with the soil biota. This introduction outlines the frame and reports on lectures by O. Dilly and J. C. Munch, L. Beyer and U. Irmler, by W. Foissner and also by U. Graefe not included in the following papers.     

Humus balancing in Central Europe—concepts,state of the art,and further challenges

Humus‐balancing methods are simple tools for the assessment of interactions between agricultural land use and soil organic matter (SOM). Aside from this commonality, approaches for humus balancing differ considerably with regard to their specific aim, scope, and methodical approach. The term “humus balance” covers both simple models to quantify SOM change in arable soils, or soil organic C (SOC) change in particular, and models that refer to the optimization of soil productivity in arable soils by calculating organic‐fertilizer demand, without quantifying SOM or SOC change. This situation naturally has caused much discussion and misunderstandings. Against this background, the aim of this review is to systematically explore the different methodical approaches to humus balancing in order to contribute to a more sophisticated discussion of this model family, its opportunities, and limitations. As humus balancing has long history as well as special actual relevance in Germany, and, lately Switzerland, we focus on these countries and discuss the different approaches that are presently available and applied there. We argue that humus balances can be roughly categorized into “ecological” and “agronomical” approaches based on their specific concepts and methodology. Ecological humus balances comprise a strong link to quantitative SOM change, while humus balances of the agronomical family refer to the maintenance of soil productivity without a quantitative link to SOM change. Lately, some models have been presented that link the two concepts. However, we identify that humus‐balancing methods often are insufficiently validated, partly because the validation of agronomical humus balances is not easily possible without a very comprehensive field‐experimental basis. Further, the comparability of different approaches even within the two concept families is low at present, indicating the need for a comparative model evaluation for a proper assessment of the methods.     

不同种类有机肥施用对黑土团聚体有机碳及腐殖质组成的影响

以吉林省农业科学院黑土有机培肥定位试验基地为平台,研究了不同种类有机肥(堆腐肥、鸡粪、牛粪和猪粪)施用对土壤及不同粒级团聚体中有机碳和腐殖质组成的影响。结果表明:与不施肥(CK)和单施化肥(NPK)相比,有机肥配施化肥显著(P0.05)增加了土壤有机碳、胡敏酸碳(HAC)和胡敏素碳(HUC)含量;同时,有机肥配施化肥也增加了不同粒级团聚体中有机碳和腐殖质碳含量,其中施用堆腐肥显著增加了各粒级团聚体中有机碳、HAC和HUC含量。不同种类有机肥相比,施用堆腐肥处理的土壤有机碳、HAC和HUC含量均高于其他有机肥处理,并与牛粪处理之间差异显著;施用堆腐肥和牛粪后,0.25mm粒级团聚体有机碳含量高于其他有机肥处理,且2~0.25mm粒级团聚体有机碳含量显著高于鸡粪处理;从不同粒级团聚体中腐殖质组分的分布来看,施用堆腐肥后,2~0.25mm粒级团聚体中HAC和HUC含量显著高于猪粪处理,而0.25~0.053,0.053mm粒级团聚体中HAC含量显著低于鸡粪处理。上述结果说明,有机肥配施化肥提高了土壤团聚体中有机碳和腐殖质碳含量,但不同有机肥的效应不同。     

Variability in soil properties at different spatial scales (1 m-1 km) in a deciduous forest ecosystem

The purpose of this research was to test the hypothesis that variability in 11 soil properties, related to soil texture and soil C and N, would increase from small (1 m) to large (1 km) spatial scales in a temperate, mixed-hardwood forest ecosystem in east Tennessee, USA. The results were somewhat surprising and indicated that a fundamental assumption in geospatial analysis, namely that variability increases with increasing spatial scale, did not apply for at least five of the 11 soil properties measured over a 0.5-km² area. Composite mineral soil samples (15 cm deep) were collected at 1, 5, 10, 50, 250, and 500 m distances from a center point along transects in a north, south, east, and westerly direction. A null hypothesis of equal variance at different spatial scales was rejected (P?0.05) for mineral soil C concentration, silt content, and the C-to-N ratios in particulate organic matter (POM), mineral-associated organic matter (MOM), and whole surface soil. Results from different tests of spatial variation, based on coefficients of variation or a Mantel test, led to similar conclusions about measurement variability and geographic distance for eight of the 11 variables examined. Measurements of mineral soil C and N concentrations, C concentrations in MOM, extractable soil NH₄-N, and clay contents were just as variable at smaller scales (1-10 m) as they were at larger scales (50-500 m). On the other hand, measurement variation in mineral soil C-to-N ratios, MOM C-to-N ratios, and the fraction of soil C in POM clearly increased from smaller to larger spatial scales. With the exception of extractable soil NH₄-N, measured soil properties in the forest ecosystem could be estimated (with 95% confidence) to within 15% of their true mean with a relatively modest number of sampling points (n?25). For some variables, scaling up variation from smaller to larger spatial domains within the ecosystem could be relatively easy because small-scale variation may be indicative of variation at larger scales.     

植草恢复对侵蚀红壤重组有机质的影响

在福建中亚热带红壤区,将侵蚀经济林(油茶)改造成人工草地(人工植草)、封山育林(自然恢复)进行生态恢复,11a后,分析A-C层土壤的常规理化性质、土壤复合量、原土复合度、腐殖质结合形态用以评价土壤肥力变化。结果表明:不同土层各指标有明显差异,其中土壤速效养分、有机质、土壤复合量表现为A层B层C层,原土复合度则表现为C层B层A层。土壤腐殖质在C层呈松结合态向紧结合态转变的趋势,其中在自然恢复区B、C层土壤的松/紧比值较A层分别下降0.149,0.458个单位,人工植草区C层土壤的松/紧比值较A层下降0.292个单位,松结合态向紧结合态转变速度较自然恢复区有所减缓。人工植草区A层土壤的有机质及有机碳总量虽低于自然恢复区,但重组有机碳含量相近,其它测定指标亦无明显差异。     

不同有机物料投入下黄河故道土壤有机碳积累特征的研究

潮土有机质含量低、结构差是限制黄河故道区作物优质高产的主要原因.通过连续施用不同种类及用量有机物料,探究有机物料投入下,黄河故道区土壤有机质的积累特征,为该区土壤快速固碳提供理论依据和参考方案.试验采用随机区组设计,设置7个处理:单施氮磷钾肥作为对照(CK),其他处理在单施氮磷钾肥的基础上增施有机肥6 000 kg/h...     

Evaluation of the different soil organic matter (SOM) pools stability in long-term field experiments of germany by physical fractionation

Samples of Ap horizons of different soil types with different clay content selected from nil plot and different fertilized plots of the long-term field experiments Thyrow, Groß Kreutz, Seehausen, Methau, Bad Lauchstädt, Straußfurt located in closely related climatic conditions had been analyzed by method of granulo-densimetric fractionation developed in Dokuchaev Soil Science Institute (Moscow). For comparison mountainous soil from long-term experiment Lauterbach located in more moist and cold conditions had been studied. Three groups of functional significant SOM fractions had been isolated: (1) light fraction (d < 2g·cm^-3), clay fraction (< 1 μm) and fraction rest. The partition of C and N accumulated in these fractions related to the level of soil fertilization and clay content had been estimated. Light fraction is the least stable: it is sensitive to the level and forms of fertilizers as well as to the changing ecological conditions. SOM interacting with clay minerals is a main factor of soil carbon level stabilization. Light fraction is responsible for decomposable SOM pool dynamics and may be appropriate criteria of its estimation.     

红壤复合胶体腐殖质的特性

对闽北6个样品测定结果表明,红壤复合胶体中C、N含量较高,其腐殖质的C/N和HA/FA、胡敏酸的芳构化度和腐殖质氧化稳定性系数均较重组小,而松结合态/紧结合态腐殖质的比值则较大.这些特性有利于土壤养分保存与供应和改善土壤结构.     

植物残体向土壤有机质转化过程及其稳定机制的研究进展

土壤有机质的数量和质量不仅是衡量土壤肥力状况的核心要素,其形成、转化及稳定过程还与全球气候变化密切相关。植物残体是土壤有机质的初始来源,但由于其腐解过程的复杂、多变性以及土壤有机质、微生物的高度异质性,植物残体向土壤有机质的转化和稳定机理尚不十分明确。本文介绍并讨论了近年来关于植物残体向土壤有机质转化相关研究的新发现,探讨了微生物源和植物源有机质对土壤有机质的贡献,概述了土壤有机质形成的微生物驱动机制,并综述了植物残体输入后土壤有机质稳定性的相关研究,最后对该研究领域未来的发展进行展望,以期能够为科学地提高土壤的固碳能力提供参考。     

不同有机物料对原生盐碱地土壤腐殖质结合形态及组成的影响

为了探究不同种类有机物料及同种有机物料的不同形态对原生盐碱地土壤腐殖质结合形态及组成的影响。以吉林省西部地区原生盐碱地为研究对象,采用连续3年的大田试验,通过大田取样和室内分析相结合的方式对其进行研究。试验设颗粒秸秆(KL)、正常玉米秸秆(JG)、羊粪(YF)、牧草(MC)和对照(CK)5个处理,采用Anderson结合态腐殖质分组法提取土壤腐殖质,研究了不同有机物料对原生盐碱地土壤腐殖质结合形态及组成的影响。结果表明:(1)施加不同有机物料较CK处理均提高了原生盐碱地土壤腐殖质含量,促进土壤中各种结合形态腐殖质含量的增加,其中KL、MC、YF 3个处理间松结合态腐殖质含量差异不显著,但相比CK处理均差异显著。对联结合态腐殖质含量影响较大,各处理间均差异显著。KL处理与其他处理稳结合态腐殖质含量差异显著,其中JG、MC、YF 3个处理间差异不显著,但相比CK处理均差异显著。紧结合态腐殖质含量各处理同CK相比差异显著,KL处理同JG处理差异显著,其他处理间差异不显著。(2)不同有机物料均能提高松/紧比值和松/稳比值,有利于腐殖质的更新及土壤肥力的提高。(3)对胡富比(H/F)的影响则表现为各处理同CK处理相比差异显著,胡富比(H/F)的增加表征着富里酸的缩合转化,进一步形成结构复杂,芳香化程度高胡敏酸,增加了土壤胡敏酸含量,促进土壤腐殖质的聚合程度以及腐殖化度的提高。综合得出,有机物料能够增加原生盐碱地土壤腐殖质含量,提高各结合形态腐殖质含量。同种有机物料不同形态作用差异显著,中颗粒秸秆(正常玉米秸秆经过粉碎高温高压处理,长2cm、直径0.5cm的圆柱形颗粒)效果远好于其他处理。     

Soil organic matter formation along a chronosequence in the Morteratsch proglacial area (Upper Engadine,Switzerland)

Global warming leads to the melting of ice caps and glaciers and, consequently, the exposure of new areas of land to the atmosphere and weathering. These areas usually have a high reactivity to both biotic and abiotic changes. Proglacial areas in the Alps usually have a deglaciation time span of around 150 years (time since the end of the “Little Ice Age” in the 1850's). We investigated a chronosequence of very young soils in the proglacial area Morteratsch (Swiss Alps) to derive time-trends of soil organic matter accumulation and evolution. Total organic C and N contents, C and N contents of the various organic matter (OM) density fractions and of the labile (oxidised by H₂O₂) and stable (H₂O₂-resistant) fractions were measured. Further characterisation of OM and the various fractions was performed using Diffuse Reflection Infrared Fourier Transform (DRIFT). Soil organic matter has been accumulated over 150 years at very high rates, values lay between 7 and 36 g C/m²/year. This led to a soil organic matter abundance of about 1–5.5 kg C/m² after 140 years. Even at the start of soil formation, a very stable fraction of soil organic matter was detectable. Stable organic matter (resistant to the H₂O₂ treatment) comprised about 6% of the total soil organic carbon and 10% of the total nitrogen. At the start of soil formation, a very high proportion of soil organic matter was present in the density fractions < 1.6 g/cm³. After about 140 years, 15% of soil organic carbon and 35–40% of the nitrogen was already present in the highest density fraction (> 2 g/cm³). With time, the quality of soil organic matter changed: a decrease of hydrophobicity, an increase in aromatic compounds in the bulk soil and a decrease in phenolic functional groups in the heaviest density fraction were detectable with increasing age. In general, stable organic matter as well as the density fraction > 2 g/cm³ had a low C/N ratio and were enriched in proteinaceous materials. The adsorption of proteinaceous materials points to a strong organo-mineral association. This process has existed since the very beginning of soil formation.     

土壤胶散复合体组成及其腐殖物质特征的研究

以吉林省3种主要耕作土壤为供试样品,采用傅积平等修改丘林的胶散分组法分离复合体,并用Kumad K法对土壤及各组复合体进行了研究.结果表明土壤中各组复合体的相对含量受土壤性质和成土条件制约,在以3组复合体的相对含量为坐标轴的三角坐标图中不 同土壤的分布区域是特征性的,三角坐标图可以作为利用胶散复合体的组成特征进行土壤发 生分类的参考依据.3组复合体的腐殖化度顺序为G0≥G1＞G2,G2组的所谓“ 活性较低“并非其腐殖质老化而是其结合状态较紧所致.     

Relation between soil organic matter and yield levels of nonlegume crops in organic and conventional farming systems

The aim of this study was to evaluate the interaction between yield levels of nonleguminous crops and soil organic matter (SOM) under the specific conditions of organic and conventional farming, respectively, and to identify implications for SOM management in arable farming considering the farming system (organic vs. conventional). For that purpose, correlations between yield levels of nonlegume crops and actual SOM level (C_org, N_t, C_hwe, N_hwe) as well as SOM‐level development were examined including primary data from selected treatments of seven long‐term field experiments in Germany and Switzerland. Yield levels of nonlegume crops were positively correlated with SOM levels, but the correlation was significant only under conditions of organic farming, and not with conventional farming treatments. While absolute SOM levels had a positive impact on yield levels of nonlegumes, the yield levels of nonlegumes and SOM‐level development over time correlated negatively. Due to an increased demand of N from SOM mineralization, higher yield levels of nonlegumes obviously indicate an increased demand for OM supply to maintain SOM levels. Since this observation is highly significant for farming without mineral‐N fertilization but not for farming with such fertilization, we conclude that the demand of SOM‐level maintenance or enhancement and thus adequate SOM management is highly relevant for crop production in organic farming both from an agronomical and ecological point of view. Under conventional management, the agronomic relevance of SOM with regard to nutrient supply is much lower than under organic management. However, it has to be considered that we excluded other possible benefits of SOM in our survey that may be highly relevant for conventional farming as well.     

Dynamic studies on nutrient uptake by crop plants (Part 14) intake and transformation of H3P32O4 in the root of wheat seedlings

In the previous reports,^1,2 it was shown that the nutrient uptake by plant roots was largely dependent on their metaboic activities, and that various sorts of respiratory inhibitors remarkably depressed phosphate uptake by plant roots.     

Phosphorus (P) Uptake mechanisms of crops grown in soils with low P status

In our previous studies, pigeonpea (Cajanus cajan L.), groundnut (Arachis hypogaea L.), and rice (Oryza sativa L.) were found to have a higher ability to take up Fe- or Al-bound phosphorus (P) than soybean (Glycine max L.) and sorghum (Sorghum bicolor L.). Phosphorus absorption characteristics like I _max, K _m, C _min, and Fe^III reduction activity of roots, and root exudates in various crops were examined with a view to analyzing the mechanisms of P uptake. Phosphorus uptake ability was largely unrelated to variations in I _max, K _m, C _min, and Fe^III reduction activity of roots. Phosphorus-solubilizing activity in anionic fractions of root exudates was detected in pigeonpea but not in rice or groundnut. Malonic acid was the major component followed by oxalic and piscidic acid. These organic acids were able to release P from FePO₄ and A1PO₄. The higher P uptake ability of pigeonpea in soils with low P fertility presumably depends on the secretion of such organic acids from roots.