Timo Kautz

Biochar Affected by Composting with Farmyard Manure

Biochar applications to soils can improve soil fertility by increasing the soils cation exchange capacity (CEC) and nutrient retention. Because biochar amendment may occur with the applications of organic fertilizers, we tested to which extent composting with farmyard manure increases CEC and nutrient content of charcoal and gasification coke. Both types of biochar absorbed leachate generated during the composting process. As a result, the moisture content of gasification coke increased from 0.02 to 0.94 g g, and that of charcoal increased from 0.03 to 0.52 g g. With the leachate, the chars absorbed organic matter and nutrients, increasing contents of water-extractable organic carbon (gasification coke: from 0.09 to 7.00 g kg; charcoal: from 0.03 to 3.52 g kg), total soluble nitrogen (gasification coke: from not detected to 705.5 mg kg; charcoal: from 3.2 to 377.2 mg kg), plant-available phosphorus (gasification coke: from 351 to 635 mg kg; charcoal: from 44 to 190 mg kg), and plant-available potassium (gasification coke: from 6.0 to 15.3 g kg; charcoal: from 0.6 to 8.5 g kg). The potential CEC increased from 22.4 to 88.6 mmol kg for the gasification coke and from 20.8 to 39.0 mmol kg for the charcoal. There were little if any changes in the contents and patterns of benzene polycarboxylic acids of the biochars, suggesting that degradation of black carbon during the composting process was negligible. The surface area of the biochars declined during the composting process due to the clogging of micropores by sorbed compost-derived materials. Interactions with composting substrate thus enhance the nutrient loads but alter the surface properties of biochars.

Research on subsoil biopores and their functions in organically managed soils: A review

The living soil is the basis for crop production in organic agriculture. Biopores are voids in the soil which were formed by the activity of soil life. The first scientific studies on biopores were published in the 1870s–90s by Victor Hensen who stated that earthworms were opening channels to the subsoil and coating them with humus, thus creating a beneficial environment for root growth. His work was originally widely recognized, but then research on biopores was neglected for many decades and was only revitalized with the rise of ecological concerns in the 1960s. In recent times, biopores have attracted the attention of agronomists with a focus on organic agriculture. New visualization techniques, such as X-ray micro computed tomography, in-situ endoscopy and nuclear magnetic resonance imaging have been applied. Biopores contribute to air transport through the soil, increase water infiltration, reduce water runoff and soil erosion, serve as preferential pathways for root elongation and can facilitate the acquisition of water and nutrients from the subsoil. The relevance of biopores for nutrient acquisition can be pronounced particularly in organic production systems, where crops are more dependent on nutrient acquisition from the solid soil phase than under conditions of conventional agriculture. Organic land-use strategies should aim to increase number, stability and quality of biopores. The biopore density can be increased by the share of dicotyledons in the crop rotation and by cultivating perennial crops with taproot systems. Moreover, density and—in particular—the quality of biopores, e.g., the nutrient contents of pore walls, can be influenced by anecic earthworms which can be promoted by adapted tillage practices.

Spatial variability of hydrolytic and oxidative potential enzyme activities in different subsoil compartments

The spatial heterogeneity of nutrient turnover in subsoils has been rarely studied in the past, although drilosphere and rhizosphere are found to be important microbial hotspots in this oligotrophic environment. In this study, we measured different potential enzyme activities in different soil compartments of subsoil and topsoil. It could be shown that the activities of hydrolases, which cleave readily available organic substrates, are significantly higher in samples from the drilosphere and rhizosphere both in topsoil and subsoil. In bulk soil, hydrolase activities decrease with depth. In contrast, oxidative enzymes, which are involved in the decay of recalcitrant organic material, are released from the microbial community especially in the bulk fraction of subsoil. This emphasizes the importance of subsoil for nutrient acquisition and gives evidence for a distinct spatial separation of microbes with diverging lifestyles.

Prokaryotes in Subsoil-Evidence for a Strong Spatial Separation of Different Phyla by Analysing Co-occurrence Networks.

Microbial communities in soil provide a wide range of ecosystem services. On the small scale, nutrient rich hotspots in soil developed from the activities of animals or plants are important drivers for the composition of microbial communities and their functional patterns. However, in subsoil, the spatial heterogeneity of microbes with differing lifestyles has been rarely considered so far. In this study, the phylogenetic composition of the bacterial and archaeal microbiome based on 16S rRNA gene pyrosequencing was investigated in the soil compartments bulk soil, drilosphere, and rhizosphere in top- and in the subsoil of an agricultural field. With co-occurrence network analysis, the spatial separation of typically oligotrophic and copiotrophic microbes was assessed. Four bacterial clusters were identified and attributed to bulk topsoil, bulk subsoil, drilosphere, and rhizosphere. The bacterial phyla Proteobacteria and Bacteroidetes, representing mostly copiotrophic bacteria, were affiliated mainly to the rhizosphere and drilosphere—both in topsoil and subsoil. Acidobacteria, Actinobacteria, Gemmatimonadetes, Planctomycetes, and Verrucomicrobia, bacterial phyla which harbor many oligotrophic bacteria, were the most abundant groups in bulk subsoil. The bacterial core microbiome in this soil was estimated to cover 7.6% of the bacterial sequencing reads including both oligotrophic and copiotrophic bacteria. In contrast the archaeal core microbiome includes 56% of the overall archaeal diversity. Thus, the spatial variability of nutrient quality and quantity strongly shapes the bacterial community composition and their interaction in subsoil, whereas archaea build a stable backbone of the soil prokaryotes due to their low variability in the different soil compartments.

Abundance of ammonia oxidizing microbes and denitrifiers in different soil horizons of an agricultural soil in relation to the cultivated crops

The role of subsoils and their microbial communities for the nutrient supply for plants is to a large extent unknown, especially in comparison to well investigated topsoil layers. Therefore, in this study, the influence of three different plant species with different rooting systems and different N uptake strategies on ammonium and nitrate levels and microbial communities involved in ammonia oxidation and denitrification was investigated in different soil horizons. Overall, our results show a higher genetic potential for both processes in topsoils than in subsoils independent of the present plant. Although we found accumulation of N in top and subsoils in plots with legumes, we could not observe an impact of the higher nitrate content on the genetic potential of denitrification and ammonia oxidation. However, differences in the ratios of ammonia oxidizing archaea to bacteria and also between denitrifying bacteria harboring genes for copper- (nirK) or cytochrome- (nirS) dependent nitrite reductase in top and subsoil samples reveal different ecophysiologies of microbes involved in N turnover in top and subsoil habitats.

In situ endoscopy: new insights to root growth in biopores.

Abstract A flexible videoscope with an outer diameter of 3.8 mm and equipped with a movable tip was used for in situ observation of roots growing in larger‐sized biopores. We were able to display root morphology and position inside of biopores and differentiate four categories of root segments.

Grouping and classification of wheat from organic and conventional production systems by combining three image forming methods

Using image forming methods, products from organic and conventional origin have been discriminated with high accuracy, but the meaning of these differences in terms of product quality is so far poorly understood. The aim of the presented study is therefore to gain further insights into the suitability of image forming methods for food quality evaluation based on wheat samples from a long-term field trial on the comparison of different organic and conventional production systems (DOC-trial). The images of the encoded samples were (1) grouped into pairs with similar image features, (2) characterized based on reference images (e.g. high resistance to degradation – low resistance to degradation), (3) ranked (according to the quality characterization), and (4) assigned to the different production methods (classified). The encoded samples from the production methods mineral fertilization, conventional production (combination of mineral fertilization and farmyard manure) and the class of organic production methods (biodynamic, bioorganic and unfertilized control) could be grouped and classified in both years. Within the class of organic production methods grouping (assigning of similar samples to image categories) and classification (assigning of categories to production methods) was partially possible. The correct grouping and classification of samples from organic and conventional production shows that different fertilization systems influence image structures in a typical and reproducible manner. The evaluation approach followed in the presented research can provide a considerable contribution to advance our understanding of quality differences between products from different farming systems or plant production measures.

Yield and bread-making quality of different wheat (Triticum aestivum L.) genotypes grown in Western Turkey

For Western Turkey (Aegean region) there is a lack of knowledge about the quality potentials of wheat varieties commonly grown in the area. In a field trial we monitored yield, grain quality and rheological properties of 18 wheat genotypes and computed a baking quality index (BQI) to facilitate the detection of high quality varieties. Grain yield ranged from 4047–6406 kg ha−1 in 2004 and from 5167–8099 kg ha−1 in 2005. Crude protein content and farinograph quality number ranged from 8.4% and 27 mm to 14.0% and 135 mm in 2004 and from 9.4% and 33 mm to 13.1% and 98 mm in 2005, respectively. Lines PFAU/WEAVER and CHILERO, such as varieties Golia and Gönen exhibit particularly high Gluten-index values (>80%) that caused favourable rheological properties with farinograph quality numbers of more than 80 mm. The genotypes differed markedly in yield and quality parameters which highlights the need to choose appropriate genotypes for production of high quality wheat in Western Turkey. A close correlation between BQI and farinograph quality number indicates that BQI can be a more valuable tool for detecting genotypes with high bread-making quality, than single quality parameters.

Einfluss langjährig differenzierter düngungsmassnahmen auf die schwefel- und stickstoffversorgung von sommergerste in berlin-dahlem (D) und tartu (Est)

In den IOSDV-Dauerfeldversuchen Berlin-Dahlem und Tartu wurden Schwefel- und Stickstoffgehalte in Boden und Sommergerste-Blättern bestimmt. Im Boden fanden sich an beiden Standorten in den organisch-mineralisch gedüngten Prüfgliedern die höchsten N- und S-Gehalte, aber auch die niedrigsten N/S-Verhältnisse. Am Standort Berlin ergab die Messung des N-Gehaltes in den Pflanzen die höchsten Werte in den Proben aus den Parzellen mit organischer Düngung; am Standort Tartu dagegen lagen in den Proben aus den Prüfgliedern mit mineralischer Düngung die Werte am höchsten. Die S-Gehalte in den Pflanzenproben vom Standort Berlin waren in den Prüfgliedern mit organischer Düngung höher als in den Prüfgliedern mit mineralischer Düngung. Am Standort Tartu ergab sich dagegen keine Differenzierung der S-Gehalte in den Pflanzenproben. In the IOSDV long-term field experiments at Berlin-Dahlem and Tartu the nitrogen and sulphur content of soil and spring barley leaves were determined. In the soil from both investigated sites the highest N- and S- contents as well as the smallest N/S ratios were found in samples from plots with a combination of organic manuring and mineral fertilization. In barley leaf samples from Berlin the highest nitrogen contents were measured in plants from organic manured field plots; in Tartu highest nitrogen contents were found in minerally fertilized plots. The sulphur contents in plant samples from Berlin were higher in plots with organic manuring than in plots with mineral fertilization. In contrast, no precise distinction was found in plant samples from Tartu.

Bacteria utilizing plant-derived carbon in the rhizosphere of Triticum aestivum change in different depths of an arable soil

Root exudates shape microbial communities at the plant-soil interface. Here we compared bacterial communities that utilize plant-derived carbon in the rhizosphere of wheat in different soil depths, including topsoil, as well as two subsoil layers up to 1 m depth. The experiment was performed in a greenhouse using soil monoliths with intact soil structure taken from an agricultural field. To identify bacteria utilizing plant-derived carbon, 13 C-CO2 labelling of plants was performed for two weeks at the EC50 stage, followed by isopycnic density gradient centrifugation of extracted DNA from the rhizosphere combined with 16S rRNA gene-based amplicon sequencing. Our findings suggest substantially different bacterial key players and interaction mechanisms between plants and bacteria utilizing plant-derived carbon in the rhizosphere of subsoils and topsoil. Among the three soil depths, clear differences were found in 13 C enrichment pattern across abundant operational taxonomic units (OTUs). Whereas, OTUs linked to Proteobacteria were enriched in 13 C mainly in the topsoil, in both subsoil layers OTUs related to Cohnella, Paenibacillus, Flavobacterium showed a clear 13 C signal, indicating an important, so far overseen role of Firmicutes and Bacteriodetes in the subsoil rhizosphere.