1,720,986 research outputs found
Regulation of winter soil mineral nitrogen and N2O emissions by cover crop termination timing
Full text linkAbstract Cover crops (CCs) are widely promoted for reducing nitrate leaching and enhancing soil fertility, yet their role in regulating winter nitrous oxide (N 2 O) emissions remains poorly understood. This field study assessed how termination timing of oil radish ( Raphanus sativus ) influenced soil mineral nitrogen (SMN) dynamics and winter N 2 O emissions across five site-years in a humid temperate climate (Germany) on contrasting soil textures (loamy and sandy). Treatments included autumn termination, spring termination, and fallow. Although CCs reduced SMN by ~ 65% compared to fallow by December, this did not lead to lower winter N 2 O emissions. Instead, cumulative emissions over a standardized 100-day winter period were highest under autumn termination (1.23 ± 0.11 kg N 2 O–N ha −1 ), followed by spring termination (0.65 ± 0.06 kg N 2 O–N ha −1 ) and fallow (0.12 ± 0.01 kg N 2 O–N ha −1 ). Emissions were higher in 2019 than 2020, associated with warmer and wetter conditions. Autumn termination also increased spring SMN levels relative to spring termination in loamy soils, but not in sandy soils, where nitrate leaching may have occurred. While microbial gene abundances indicated greater nitrification and denitrification potential under autumn termination, they did not correlate with actual N 2 O fluxes. These findings suggest that autumn termination can enhance winter emissions, whereas delayed termination may shift emissions to spring, particularly under fertilized conditions. Site-specific CC management that considers termination timing, soil texture, and climatic context is essential to balance nitrogen retention with N 2 O mitigation.Bundesministerium für Ernährung und Landwirtschaft https://doi.org/10.13039/501100005908Georg-August-Universität Göttingen 50110000338
Strategies for sustainable agricultural land use in Western Siberia (Russian Federation)
Full text linkThe growing global population and the ongoing loss of arable soils increase the pressure on agricultural production. In conjunction with climate change, this causes new challenges for agricultural production systems worldwide and requires a more sustainable approach for the future. The concept of ‘sustainable land management’ (SLM) is known as a concretisation of the sustainable development goals in the field of agriculture. The Western Siberian grain belt covers 1 million km² in Asiatic Russia and is of global importance for agricultural production as well as an important carbon sink and of international interest for biodiversity preservation.
The work was conducted as part of the interdisciplinary German-Russian SASCHA project, which focused on SLM strategies at the intersection of climate change and land-use change in Tyumen region of Western Siberia. The objective of this work was to identify strategies for sustainable agricultural land management in Western Siberia with a focus on arable farming issues. Therefore, specifically the following research questions were addressed: (i) What does the history of agricultural land use across the Western Siberian grain belt tell us for developing future strategies? (ii) How can the eco-efficiency of Western Siberian cereal cropping systems be increased under the strain of changing climatic conditions? (iii) Is soybean cultivation capable of diversifying crop rotations in the southern part of Western Siberia?
Triggered by the dissolution of the Soviet Union and the collapse of the state farm system, massive land-use changes took place in the region. A normalised input-oriented intensity index was developed to quantify these changes and patterns in land-use intensity (LUI). Based on subnational, annual statistical data, two separate indices for cropland and grassland were calculated and applied on two spatial scales (provinces and districts). The spatio-temporal analysis showed significant opposite trends: decreasing intensity on grassland by -0.015 LUI units per year and intensification on cropland by +0.014 LUI units per year. The land-use changes that accompanied the post-Soviet transition from a planned to a market-driven economy also implied substantial socio-economic consequences for agricultural production. Based on the LUI analysis, locally adapted SLM scenarios were developed for Tyumen province and priority areas for implementation were identified. The findings clearly showed the need for having a different SLM strategy for grassland (predominantly used by livestock of households) and cropland (predominantly managed by large agricultural enterprises), which have to be addressed specifically by the different land users. Two major strategies were derived for the Western Siberian grain belt: low-intensity grazing for grassland conservation and sustainable intensification (SI) on cropland instead of cropland expansion.
The system of conservation agriculture is a known possibility for SI in dryland cropping systems. Particularly under climate change predictions of drier and warmer growing conditions, no-till farming could be a promising way to increase eco-efficiency in Western Siberian cereal production systems. Therefore, a full-factorial split-split-plot field trial was conducted on a farmer’s field to test adaptations of tillage (usual conventional tillage ‘CT’ vs. no-till ‘NT’), seeding depth (usual deep 6.5 vs. shallow 4.5 cm) and seeding rate (usual high 600 vs. reduced 450 grains m-2) for the potential to increase water use efficiency and grain yield. Results from two above-average wet and cold growing seasons showed significantly better soil water storage of NT (+40 %) and no adverse effect on spring wheat grain yield and grain quality. Impacts of variations in seeding rate and seed placement were less pronounced. The highest yields of 3.19 and 3.82 t ha-1 were observed with NT treatment in 2014 and 2015, respectively.
Other alternatives implemented to increase eco-efficiency of dryland cropping systems are enhanced fertilizer strategies. In Western Siberia, nitrogen (N) fertilizers (urea or ammonium-nitrate ‘Selitra’) in cereal production are commonly banded during sowing directly into the seed furrow. The performance of a new kind of slow-release fertilizer was tested in a field trial under on-farm conditions. A modified urea with silicate coating and urease inhibitor was compared in four N-levels (25/50/75/100 %) to 100 % of conventional urea, 100 % of Selitra and an unfertilized control in RCBD. Results showed significant differences in soil nitrate availability but no differences in ammonium release and no significant impact on grain yield or quality. From the results of this field trial there seemed to be no beneficial advantage of the tested novel slow-release fertilizer so far. More field site years and further improvements of the laboratory-scale fertilizer production are needed for scientifically founded results.
Climate change is likely to considerably affect future growing conditions in regions around the current high-latitude boundaries of agricultural production. Specifically for soybeans, this leads to a northwards shift of the northernmost limit for cultivation. Therefore, the effect of soybean seed inoculation with Bradyrhizobium japonicum was investigated in comparison to an untreated control in a small-scale split-plot field trial under high latitude conditions. Leaf chlorophyll content by SPAD-meter readings was used as proxy for biological nitrogen fixation. Inoculation was always successful, since nodulation took only place in plots with seed treatment. Effect sizes of SPAD-values were significantly positive at beginning of seed filling but did not differ earlier. Except for the warmest site year, inoculation had no impact on seed yield and protein yield. Under cold growing conditions of high latitude regions, temperature sums seemed to limit soybean yield and the effectiveness of inoculation with B. japonicum. To implement soybeans as legumes in crop rotations, nevertheless, inoculation is mandatory, since soils in high latitudes lack soy-specific rhizobia bacteria.
The trials and studies compiled in this thesis are examples of contributions to SLM strategies on varying spatial and temporal scales. Besides all the promising benefits of the described SI applications, some drawbacks must be considered: NT and CA often result in increased herbicide applications, genetically modified varieties (GMO) and herbicide resistances. Diverse crop rotations including legumes, however, would be a base for resilient cropping systems with a reduced reliance on a single herbicide. Moreover, Western Siberia has a great potential to become a key contributor to non-GMO dryland cropping.
Even though the focus of this thesis was on agronomic strategies, the integration of livestock and arable farming is crucial for sustainable agriculture. The agricultural system of the Western Siberian grain belt could considerably benefit from crop-livestock integration by better soil fertility and enhanced nutrient management. The current observed trend of cropland intensification, however, will require increased attention paid to the sustainability of Siberian arable farming. Considering the forest steppes’ peculiarities and the unique land-use history, SI implemented on cropland and a moderate grazing regime on grassland seems to be the best combination for SLM across the Western Siberian grain belt
Frühjahrs-Düngung mit grünem Ammoniak – Chance für den Ökolandbau?
Full text linkBald werden wir in einer de-karbonisierten Wirtschaft leben und CO2-neutraler N-Dünger aus grünem Ammoniak wird Standard in der Landwirtschaft. Dieser könnte in streng reglementierten Grenzen eine Option für den Ökolandbau sein, da sich die Ressourcennutzung erhöhen ließe ohne große Umweltwirkunge
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Potential of Adapted Tillage and Seeding Operations for Sustainable Spring Wheat Cultivation Under Climate Change in Western Siberia
No full textAbstractWestern Siberia is of global significance in terms of agricultural production, carbon sequestration and biodiversity preservation. Land use intensities in Tyumen province in Western Siberia are relatively low but increasing on cropland since the dissolution of Soviet Union and the following collapse of the state farm system. Climate change modelling predict an increase of drought risk for this region. Together, these changing conditions lead to upcoming challenges for sustainable crop production.The German-Russian interdisciplinary research project “SASCHA” aims to provide sustainable management practices to cope with these far-reaching changes for Tyumen province. In particular, on farm scale strategies to improve efficiencies in crop production systems are being developed. Therefore, a factorial field trial (completely randomized block design, 3 replications) with different tillage and seeding operations was installed in 2013, growing the regional most dominant crop spring wheat on 10ha under practical conditions. Even if optimal seed rate and seed depth have been identified since decades, changing climate conditions as well as advancement in technology and breeding require a look on these details again. A main goal of the project is ability of implementation, thus all tested trial parameters are easily applicable with standard equipment on ordinary farms.After 2 years, results indicate significant impacts of reduced tillage on soil water storage, nitrogen mineralization and plant development. Depending on yearly weather conditions, effects of seeding adjustments vary. In conjunction with progressing climate change there seems to be high potential for enhanced production efficiency by no-till systems for the study region in Western Siberia. Under these environmental conditions, an optimized soil water storage management means an enhanced resource use efficiency at all. This way of sustainable intensification of agricultural production will also preserve carbon stocks and biodiversity, as there is no need for expanding arable land into currently unused areas
Impact of Rhizobia Inoculation for Sustainable Soy Cultivation in Western Siberia
No full textAbstractDriven by an increasing demand for food and fodder and changing climate conditions, the production of soy (Glycine max L.) in Western Siberia increases. Higher temperature sums and longer growing seasons allow new crop rotations with partial substitution of peas by soybeans. Both legume crops need specific rhizobia bacteria to be supplied by biological nitrogen fixation. Whilst bacteria supply for peas usually is sufficient, Siberian soils lack the soy-specific strains (Bradyrhizobium japonicum). Therefore, bacteria material is usually added manually, especially if soy is planted on a field for the first time. This inoculation procedure of seeds is not common in Siberia, hence it is uncertain if soy benefits from legume N2-fixation potential there.Within the framework of the interdisciplinary German-Russian research project “SASCHA” on sustainable land management a study about the capability of soy cultivation in Western Siberia was carried out. In a field trial (completely randomized block design, 4 replications) the effects of rhizobia inoculation at 4 different varieties from Europe and Siberia were investigated by using Minolta SPAD-meter readings as indicator of fixation capacity and comparing yields as well as bean protein content.Results after two years show significant higher leaf chlorophyll content (SPAD) with inoculation compared to control (without treatment), differences were rising over time (Fig. 1). According to the measured SPAD differences also protein content at beans from treated plants was higher (+10%, significant p<0.01) at constant yields
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