Einfluss der Düngung mit Gärrückständen aus der Biogaserzeugung auf den Ertrag von Silomais und auf die bodenmikrobielle Aktivität

Organic manuring with slurry from biogas plants may contribute to plant nutrition and maintenance of soil fertility in organic farming. However, the chemical properties of biogas slurry depend markedly on substrate input and process technology. The aim of this study was to gain more insights into the relationship between the quality of biogas slurry and its influences on plant and soil parameters when applied as organic ma-nure. We studied the effects of slurries from two different biogas plants on yield of maize and soil microbial activity in a two-year field experiment. The investigation took place on a loam-clay soil near Göttingen, Lower Saxony. Biogas slurry A was obtained from a biogas plant with liquid pig manure as main input, slurry B originated from a biogas plant operated with renewable primary products. Slurries were applied as 30 and 60 m3 ha-1 respectively. Highest yield of maize was obtained in the treatment with slurry B when given as 60 m3 ha-1. N content in biomass of maize was the highest in the treatment with slurry A (60 m3 ha-1). β-glucosidase activity was not affected by any of the slurries. Conversely, both slurries were found to significantly increase dehydro-genase activity as well as total soil C and N contents

Growth of barley (Hordeum vulgare L.) roots in biopores with differing carbon and nitrogen contents

Large sized, vertical biopores can provide preferential pathways for root growth, hence facilitating the exploration of great soil depths by crop roots. This is of particular importance for organic production systems, where crops are more dependent on nutrient acquisition from the solid soil phase than under conditions of mainstream agriculture. The relevance of biopores for nutrient acquisition from the subsoil can possibly depend on their individual properties. The aim of this study was to test how different chemical pore wall properties affect the growth of barley (Hordeum vulgare L.) roots in large sized biopores. Bulk soil, pore wall material and roots from individual biopores were collected from three depth layers in 45-75 cm soil depth. C and N contents in the pore walls were up to 3 times higher than in the bulk soil. A large variation of C and N contents between the walls of individual biopores indicated that the quality of the pore wall is a function of pore colonization by earthworms over time. N-rich pores hosted more roots than N-poor pores. It is concluded that elevated C and N concentrations in pore walls can facilitate the exploration of the subsoil by crop roots

Charakterisierung des Wurzelwachstums in Bioporen mit in situ Endoskopie

More information on root growth in biopores is needed for quantifying nutrient acquisition from the subsoil. The article presents an approach for using in situ endoscopy in biopores that allowed to quantify root-soil contact and detect differences in root morphology and orientation between mallow (Malva sylvestris L.) and spring wheat (Triticum aestivum L.). While 85 % of all wheat roots entered the biopores laterally from the bulk soil, mallow roots in biopores grew predominantly (69 %) with vertical orientation and established contact to the pore wall predominantly via lateral roots. The current status and future perspectives of the method are discussed

Root growth response of spring wheat (Triticum aestivum L.) and mallow (Malva sylvestris L.) to biopore generating precrops

Little is known about root growth in biopores. The aim of this study was to quantify differences of root-length density (RLD) in biopores between a tap root system (mallow) and a fibrous root system (wheat). A field experiment was undertaken near Bonn, Germany on a Haplic Luvisol developed from loess. Lucerne (Medicago sativa L.) and chicory (Cichorium intybus L.) were grown as precrops in a field trial followed by spring wheat (Triticum aestivum L.) and mallow (Malva sylvestris L.). Biopore density was measured on horizontal areas of 50 x 50 cm. RLD was estimated using the profile wall method to 160 cm soil depth. Roots growing in biopores with a diameter > 2 mm were recorded separately from the roots in the bulk soil. Biopore density was higher after chicory compared to lucerne cultivation. RLD of wheat in the topsoil was higher and in the subsoil lower than RLD of mallow. RLD in biopores of mallow was higher than of wheat. Both crops showed higher RLD in biopores after chicory. The results indicate that the response of root growth to the presence of biopores is more pronounced for tap root systems than for fibrous root systems

Bioporen: Ihre Bedeutung für das Wachstum der landwirtschaftlichen Kulturpflanzen

The subsoil (i.e. the soil beneath the ploughed soil layer) provides a large potential reservoir of nutrients for crops but the conditions for nutrient acquisition are generally adverse due tolow organic matter contents, low nutrient concentration in the soil solution, low microbial activity and high bulk density. However, the structural heterogeneity of the subsoil including biopores created by roots and earthworms requires a more detailed view on nutrient acquisition processes. First results from the DFG research unit ‘Crop Sequence and the Nutrient Acquisition from the Subsoil’ have shown that cultivation of perennial fodder crops with taproot systems can result in enhanced biopore density in the subsoil and increased root-length density of subsequent crops. Observations with endoscopes revealed that 80-90 % of roots growing in biopores established contact with the pore wall thus potentially accessing the nutrients stored therein

Wurzelwachstum und Nodulation von Luzerne: Einfluss von Bioporendichte im Unterboden und Nährstoffgehalt im Oberboden

Das Ziel dieser Studie war, die Auswirkungen großlumiger Bioporen und Bodennährstoffgehalte auf Nodulation von Luzerne Wurzeln zu quantifizieren. In einem Feldversuch auf einem tiefgründigem Lössboden wurde Luzerne (Medicago sativa L.) angebaut (i) auf nativem, nährstoffreichem Boden oder in Parzellen, auf denen der native Boden entfernt und mit Boden aus ungedüngten Parzellen eines Dauerfeldversuchs ersetzt wurde sowie (ii) nach Anbau bioporen-generierenden Wegwarte (Cichorium intybus L.) mit Pfahlwurzelsystem oder nach Rohrschwingel (Festuca arundinacea Schreb.) ohne Pfahlwurzeln. Wurzellängen-Dichte und Nodulation wurden mit der Profil-Wand-Methode und an Monolith Proben quantifiziert. Spross-Wachstum und Nährstoff-Aufnahme von Luzerne wurde durch nährstoffarmen Boden reduziert aber blieb unbeeinflusst von den Vorfrüchten. Hohe Nährstoffgehalte im Oberboden und hohe Bioporen-Dichte im Unterboden hatten tendenziell fördernde Wirkungen auf die Anzahl der Knöllchen, aber die Unterschiede waren nicht signifikant. Der Anteil der Knöllchen in großlumigen Bioporen im Unterboden betrug in der Regel zwischen 20 und 40 %. Da das Volumen der solcher Bioporen nur etwa 2 % des gesamten Bodens ausmacht, lässt sich schlussfolgern, dass Bioporen bevorzugte Orte der Nodulation und möglicherweise der N2-Fixierung sind

Metabolic activity of Hordeum vulgare, Brassica napus and Vicia faba in Worm and Root type Biopore Sheaths

Aims: Biopores offer favorable chemical, biological and physical properties for root growth in untilled soil layers. There they are considered as nutrient “hotspots” with preferential root growth. However, the literature lacks a quantification of metabolic activity due to nutrient acquisition of main crops while growing in the biopore sheath. Methods: A pot experiment was performed to map the metabolic activity of roots, as indicated by pH change. The roots of spring barley (Hordeum vulgare L.), spring oilseed rape (Brassica napus L.) and faba bean (Vicia faba L.) were growing through the biopore sheath influenced by an earthworm (Lumbricus terrestris L.) or a taproot (Cichorium intybus L.), in comparison to subsoil without a pore (bulk soil). pH sensitive planar optodes were applied in order to image a planar section of the sheath, while preserving an intact biopore sheath during the experiment. Results: Roots were first found in the field of view in worm biopore then root biopore and bulk soil. At time of the first measurement the pH value was highest in worm biopore sheath (LS-Mean±SEM: 7.16a±0.11), followed by root biopore sheath (6.99ab±0.12) and bulk soil (6.61b±0.12). In spring oilseed rape a significant alkalization (+0.80 Δ pH) was found over time in bulk soil. Faba bean significantly acidified the root biopore sheath (-0.73 Δ pH). Spring barley showed no significant pH changes. Conclusions: The results of the current study reveal a trend of faster root growth through biopores and a higher initial pH value in the biopore sheaths compared to the bulk soil. Biopores serve not only as an elongation path for roots, but their sheaths also provide an environment for root activity in the subsoil

Anbauerfahrungen mit Artischocken im Organischen Landbau

The aim of this study was to gain experience in the organic cultivation of artichokes (Cynara scolymus L.) under the condition of the temperate climate of the Lower Rhine Bay. The effects of reducing the number of buds by removing bastard branches on the yield of two cultivars were tested in a field experiment. Cultivar ‘Imperial Star’ yielded up to 10.31 t FM / ha, for cultivar ‘JW 109’ the yield was up to 7.63 t FM / ha. In both cultivars, removing bastard branches resulted in higher bud weight, whereas total yield per ha was reduced

Veränderung der Effizienz der Regenwurmaustreibung mit Senfsuspensionen im Tagesverlauf

We tested the effect of sampling time on the efficiency of mustard extractions for earthworms in a field study. On an organic experimental farm (alluvial loams; Hennef/Germany) earthworm extractions were started on two consecutive days hourly from 10 am to 5 pm and 6 pm respectively. Significant effects of daytime on extracted earthworm biomass occurred on both days. Maximum biomass was extracted in the early afternoon in each case. Additional pot experiments have shown a significant temperature dependence of the mustard extraction method which at least partially explains the differences in on-site extracted earthworm biomass in the course of the day. We conclude that daytime has to be considered as a factor when using mustard extraction methods. When used in factorial field experiments, the extractions in different field plots should therefore be operated simultaneously

Biopore characterization with in situ endoscopy: Influence of earthworms on carbon and nitrogen contents

Biopores have been shown to be enriched with plant available nutrients as compared to the surrounding bulk soil and therefore are considered hot spots for the nutrient acquisition especially in the otherwise nutrient-poor subsoil. However, depending on their individual biography, i.e. colonization by plant roots or earthworms, different nutrient status can be assumed. In this study, individual biopores were characterized with respect to signs of earthworm passage using in situ endoscopy, a non-destructive technique for display of pore wall characteristics. Subsequent sampling and analysis of biopore linings and blockages revealed that only biopores with visible earthworm coatings had significantly higher C and N contents as compared to the surrounding bulk soil. The results of this study highlight the special role of earthworms for enriching biopores with nutrients and underline the value of biopores for the nutrient acquisition from the subsoil