Workshop: Der Humus und wir, oder: Was bringt der Humus dem Ökolandbau und was bringt der Ökolandbau dem Humus?

Impulsreferate: - Wilfried Denker, Landwirt - Helmut Frank, Bioland, Augsburg - Thomas Schindler Landesbetrieb Landwirtschaft Hessen - Dr. Andreas Gattinger, FiIBL, Frick, Schweiz - Dr. Christian Bruns, Universität Kassel/Witzenhausen - Dr. Christopher Brock, Universität Giessen Ökolandbau kann Humus aufbauen - allerdings ist dies kein automatischer Mitnahmeeffekt, sondern erfordert ein aktives Humusmanagement. Forschungs- und Entwicklungsbedarf besteht insbesondere bei pflanzenbaulich machbaren Systemen mit ausreichender Versorgung mit organischer Substanz im Hackfrucht-/Gemüsebau. Betriebe sollten Humusbilanzen für ihre Flächen erstellen, um die eigene Humuswirtschaft zumindest grob einschätzen zu können. Zur Unterstützung der Betriebe sollte die Humusbilanzierung vorgeschrieben werden, ohne jedoch mit neuen, über die bestehenden Regelungen hinausgehenden Anforderungen an Fruchtfolgegestaltung und Düngung verbunden zu werden. An anwendungsbereiten Humusbilanzmethoden für den Ökolandbau stehen aktuell zur Verfügung: Methode nach Kolbe: https://publikationen.sachsen.de/bdb/artikel/13446 Humusbilanzmethode für den Ökolandbau nach Leithold et al.: http://www.soel.de/publikationen/oekologie_und_landbau/downloads/oel105_32_35_leithold_huelsbergen.pdf Eine vergleichende Bewertung dieser beiden Ansätze steht noch aus, so dass aktuell keine eindeutige Empfehlung für die eine oder andere Methode ausgesprochen werden kann. Es besteht weiterhin Forschungsbedarf zur besseren und möglichst quantitativen Einschätzung der Bedeutung des Humus für die Produktivität von Ackerböden, und zur Beeinflussung des Humus durch Pflanzenproduktionssysteme. Praxisanwendbare Instrumente zur Einschätzung der Humusversorgung (Humusbilanzen, einfache Modelle) sind weiterzuentwickeln. Die Versorgung der Böden mit organischer Substanz und die gezielte Anwendung organischer Substrate sind wichtige Elemente im ökologischen Pflanzenschutz. Allerdings können Zielkonflikte entstehen, insbesondere in Hackfruchtfolgen/im Gemüsebau. In der Forschung besteht Bedarf an komplexen Betrachtungen der Humuswirtschaft, die Fragen der Bodenqualität, der Pflanzengesundheit und der Ökonomie einbeziehen. Forschungsbedarf besteht weiterhin zu Suppressivität von Böden (Unterdrückung von Pathogenen). Hier wäre zunächst eine Meta-Analyse in Langzeitversuchen anzustreben

Humusbilanzmethoden als Prognose- und Bewertungsinstrumente im ökologischen Landbau – allgemeiner und spezieller Anpassungsbedarf

Humus balances are intended to serve as instruments to support humus management in practice. Still, urgent need for adaptation especially with regard to apllication in organic farming has been stated. Results presented in this paper show that there in fact is a difference in humus repro-duction between conventional and organic farming that is not recognized in balance methods. In addition, the results exhibit a big uncertainty in balance results. They are pointing out basic problems of humus balance methods that are likely to be caused by an insufficient consideration of site-specific factors of the humus household and their interaction with farming

Bringt „Öko“ mehr Humus? Einschätzung der aktuellen Humusbilanzen der ökologisch und der konventionell bewirtschafteten Ackerfläche in Deutschland

We calculated humus balances for organic and conventional cropland in Germany and compared them to each other in order to find out whether organic farming comprises a better humus reproduction than conventional farming, as commonly assumed. Applying a dynamic humus balance model that was parametrized based on data from agrostatistical reports we yielded comparable balances for the two farming systems. The reason was mainly a considerably lower stocking on organic farms, and the low N supply. However: a superior cropland structure brought the balance to the same level as with conventional agriculture despite of these factors. Due to shortcomings in model parametrization caused by the available data base, results may not be over-interpreted. Still, it can be concluded that the promotion of humus stocks in arable soils is not a label effect of organic farming, but requires active management, especially with the present specialization trends

Herleitung und Prüfung statischer Humusbilanzkoeffizienten für den ökologischen Landbau

Humus balances are tools for the assessment of humus management in farming practice. We evaluate the coefficients for organic farming systems that are comprised in the actual draft revision of the German standard method for humus balancing by VDLUFA. Specific coefficients for organic farming are supported by the N balance in the soil-plant system under organic management, and the coefficients under survey relate to plausible yield levels. The evaluation of the balances without and with application of farming-system specific coefficients in four organic long-term field experiments in Germany showed overall weak correlations of all balances with the test criteria soil C change, winter wheat yield level, and N balance, but balancing with specific coefficients yielded slightly better results than unspecific balancing

A PRACTICE APPLICABLE MODEL FOR THE ASSESSMENT OF MANAGEMENT IMPACT ON ORGANIC MATTER IN ARABLE SOILS

We present the HU-MOD-2 model for the assessment of management impact on organic matter levels in arable soils. The model aims at optimal applicability as a management support tool in framing practice and therefore requires only easily available input data. In validation, the tool proved to be capable of giving a rough estimate on soil organic matter changes in arable soils. Taking into account the low demand for input data, the modeling error seems tolerable for a practice applicable decision support tool

MIXEd livestock farming for improved sustaiNABiLity and robustnEss of organic animal production (MIX-ENABLE) WP 6.1. Map of agricultural consultants active in organic mixed farming

Integrating two or more animal species with crop production or agroforestry on a farm potentially provides many benefits including more efficient pasture use and parasite management. However, organic mixed livestock farms (OMLF) tend to specialize or display limited integration between farm components. This limited integration may reduce the practical benefits of OMLF. Therefore, we aim to (i) characterize OMLF in Europe, especially their level of integration between farm components, (ii) assess their sustainability and robustness to adverse events, (iii) compare their performances with those of specialized farms, (iv) integrate the knowledge developed on OMLF into models that can simulate their performances against climatic and economic variability, (v) conduct farm-level experiments to generate knowledge about OMLF (to feed into the models) and (vi) co-design with farmers more sustainable and robust OMLF. We will survey OMLF to collect technical and socio economic data. Then we will enlarge existing concepts and methods to assess the level of integration between farm components and apply these methods to surveyed OMLF. We will also develop an indicator system for integrated assessment of OMLF and apply it to connect the sustainability and robustness of surveyed OMLF with their level of integration among farm components. In parallel we will conduct farm-level experimentation of organic specializedand mixed livestock situations for the comparison of specific aspects of animal husbandry (e.g. pasture use, animal health). We will extend farm simulation models to OMLF and analyze the benefits and drawbacks of livestock diversity. Using these models, we will develop and implement participatory methods to co design with farmers sustainable and robust OMLF. To inform practice and policy-making, we will communicate our results to shed light on the potentialities of OMLF and the way to manage it sustainably or the way to reach it starting from a specialized farm. A map of consultants in all partner countries was prepared to support stakeholder engagement and knowledge dissemination in the project. Agricultural consultants are the most important actors that mediate the interaction and knowledge flows between the scientific and practice sector. The task was lead by Forschungsring