Effizienz verschiedener Zwischenfruchtvarianten unterschiedlich hohen Leguminosenanteils in der Reduktion der Mineralstickstoffgehalte im Boden unter pannonischen Standortbedingungen

Der Zwischenfruchtanbau ist einerseits wichtig für die Speicherung von Stickstoff, der Vermeidung von Bodenerosion, der Bodenbelebung u.a.m. Andererseits muss gerade im pannonischen Klimagebiet mit einem Wasserverbrauch gerechnet werden, der zu Ertragseinbussen in den Folgekulturen führen kann. Ziel ist daher die Prüfung der Auswirkungen unterschiedlicher Zwischenfrüchte auf den Wasserhaushalt, den Stickstoffhaushalt und den Ertrag der Folgekulturen. Der Versuch wird in einer fünffeldrigen Fruchtfolge mit den ökonomisch wichtigsten Kulturarten des biologischen Landbaus (ausgenommen Feldgemüseanbau) unter Berücksichtigung von Fruchtfolgepaaren mit unterschiedlichen Zeitspannen für den Zwischenfruchtanbau angeleg

Stickstoffaufnahme und Biomasseertrag von Zwischenfrüchten und deren Auswirkungen auf Bodennitratgehalte und die Folgekultur unter den Bedingungen des Ökologischen Landbaus im pannonischen Klimagebiet

Data on the potential of catch crops to reduce soil nitrate contents, on their N accumulation and biological nitrogen fixation (BNF) are lacking for organic farming in the dry, pannonic region of Eastern Austria. The effect of legume, non-legume, and legume + non-legume crops used as catch crops on inorganic soil nitrogen, crop biomass and crop N, and BNF were tested in comparison to bare fallow. Non-legumes and legumes + non-legumes were more efficient than legumes in reducing inorganic soil N contents in autumn and nitrate contents in soil solution from the subsoil in winter. This reduction in inorganic soil N did not last until March of the following year due to N mineralisation from the mulch. The legume + non-legume mixture contained a larger amount of crop N than both legumes and non-legumes. This was due to the combined effect of soil-N uptake by the non-legumes and BNF by the legumes in the mixture

Wasserhaushaltsmessungen in ökologisch bewirtschafteten Leguminosenbeständen im Trockengebiet Ostösterreichs

Durch die Kombination von Feldmessungen und Simulation werden Änderungen im Bodenwassergehalt erfasst und Wasserbilanzen errechnet. Es ist vorgesehen in vier Plots (Meßprofile) die Bodenwasserspannung und den Wasseranteil online zu erfassen. Diese Profile dienen zur Erfassung der zeitlichen Auflösung an einem Standort und werden auch für die Kalibrierung der Simulation herangezogen. Die Simulation bietet die Möglichkeit unterschiedliche Szenerien zu bearbeiten und Sensibilitätsanalysen durchzuführen. Die Kombination der Messung und der Simulation ist eine sehr kostengünstige und flexible Vorgangsweise zur umfassenden Beschreibung der Stoffumsetzungsprozesse im Boden unter verschiedenen Bedingunge

Ertragsbildung von unterschiedlichen Kulturarten für die Biogaserzeugung im ökologischen Landbau

Energy crops for biogas production need to be integrated into sustainable and site adapted crop rotation systems, minimising the competition with food production. Luzerne/clover (-grass), sun flower, maize, green-rye + maize and vetch-rye + maize were compared at two sites in Austria with semi-arid (Raasdorf) and humid (Lambach) conditions with and without biogas slurry application. The yield of legumes and fertilised non-legumes at the humid site were 9 % to 56 % higher then at the semi-arid site. The 2-crop system maize following vetch-rye achieved the highest yields at both sites. Slurry from the biogas plant increased the yield only at the humid site

PathOrganic – Risks and Recommendations Regarding Human Pathogens in Organic Vegetable Production Chains

PathOrganic assesses risks associated with the consumption of fresh and minimally processed vegetables due to the prevalence of bacterial human pathogens in plant produce. The project evaluates whether organic production poses a risk on food safety, taking into consideration sources of pathogen transmission (e.g. animal manure). The project also explores whether organic versus conventional production practices may reduce the risk of pathogen manifestation. In Europe, vegetable-linked outbreaks are not well investigated. A conceptual model together with novel sampling strategies and specifically adjusted methods provides the basis for large-scale surveys of organically grown plant produce in five European countries. Critical control points are determined and evaluated and factors contributing to a food safety problem are analyzed in greenhouse and field experiments. The project aims at developing a quantitative risk assessment model and at formulating recommendations for improving food safety in organic vegetable production

Effect of catch crops on N dynamics and following crops in organic farming

Green manure catch crops promote the sustainability of agricultural systems by reducing soil erodibility and by nutrient uptake and transfer to the following main crops. This effect efficiently reduces the risk of nitrate leaching. Biological nitrogen fixation by legume catch crops is an additional benefit, mainly in organic farming. Such crops may, however, reduce nitrogen uptake from the soil and increase nitrate leaching. Additionally, under drought conditions, their extra water consumption may outweigh the beneficial effects. To determine the best catch crop management in stockless organic farming under dry, Pannonian site conditions in eastern Austria, four treatments were compared in 2002 and 2004: (1) legumes: field pea, common vetch and chickling vetch, (2) non-legumes: phacelia, oil radish and turnip, (3) a legume and non-legume mixture (all mentioned components), and (4) a bare fallow control. Our results show that catch crop biomass and N yield, biological N fixation, and crop N uptake from the soil were about 4 times higher under moderately dry conditions in 2002 than under drought conditions in summer and autumn 2004. In 2002, the legume/non-legume mixture had the highest biomass and N yield and the highest biological N fixation. Both the legume/non-legume mixture and the non-legumes were more efficient than legumes in N uptake from the soil (+32 kg N ha$^{-1})$; and in reducing both soil inorganic N contents by –45 kg N ha$^{-1}$ and nitrate concentrations in soil solution by –20 mg N L $^{-1}$. These findings show that the legume/non-legume mixture combined the positive effects of non-legumes and legumes. In 2004, catch crop effects did not differ except for their above-mentioned effect on inorganic N contents. The only pre-crop effect was that of legumes compared with non-legumes on spring barley grain dry matter of +0.6 Mg DM ha$^{-1}$ and grain N yield of +17 kg N ha$^{-1}$ in 2005. The water consumption of catch crops never adversely affected the following crops