Long-term trials in Europe and North America, experience and research approaches

An overview will be provided on scientific subjects and research approaches based on 25 long-term field studies located in Europe and North America. Basically, factorial field experiments and farm studies can be distinguished. Key results of soilparameters and crop yields are summarized. Characteristic benefits aa well as inherent drawbacks of long-term experiments are discussed

Enzymatic browning of potatoes is greatly reduced with organic fertilization compared to mineral fertilization

Enzymatic browning of tubers owing to mechanical injury is assessed to indicate bad quality, mainly for visual reasons. Browning is also a serious problem during processing of potatoes. The effect of farmyard manure and mineral fertilization at three levels (50, 100, 150 kg total N per hectare) on darkening of potato extract was investigated in three years in a field trial. The extinction of the extract was measured at 400 nm for two days at three dates during the storage period from autumn to spring. The extract of organically fertilized tubers hat a lower extinction compared to the mineral treatments. This difference occurred right at the beginning of the test with the fresh extract as well as during the following two days, when darkening continued with all samples, but with different extent. Whereas increasing manure levels reduced browning, higher amounts of mineral fertilizer intensified the dark colour. During storage from October to April the extinction showed no clear tendency. Polynomial regressions were calculated for the extinction values during the two days after production of the extracts. The R2 values decreased during storage from 0.95 - 0.98 in November to 0.80 - 0.91 in February. This may be interpreted as a hint of progressing disintegration

Monitoring nutrient turnover during composting has to be based on a constant reference parameter. Is total ash content really a good choice?

The total ash content is usually considered to be fairly constant during the composting period, apart from addition of minerals by precipitation and losses by seepage. However, our field trials with farmyard manure have shown that the ash fraction insoluble in hydrochloric acid increased much more than the soluble fraction in the same time. If changes are merely caused by composting intensity (e.g. organic matter degradation), both fractions should be accumulated in the same degree. It is hypothesized that the higher rise of the HCl-insoluble fraction indicates a higher amount of soil material in the heaps at the end compared to the beginning of composting, as the insoluble fraction originates mainly in soil-borne silicates while the soluble fraction is derived from (plant and animal) organic matter. Contamination with soil material could occur when turning the heaps by machine as it has been done several times in this trial. This explanation is supported by our results of another composting study carried out for several years without turning the heaps. No such disproportional changes of the soluble and insoluble ash fractions have been observed under these conditions. It is suggested to use the HCl-soluble ash contents as a reference parameter, at least in field trials without absolutely controlled conditions. The aim of this study was to improve the scientific methods for composting organic materials under practical farming conditions

Biodynamic approaches in research and development

The paper deals with particular aspects of biodynamics in research and development. It describes the basic background (anthroposophy), the biodynamic preparations with respect to research questions, the need for education and training is pointed out. As a consequence of this situation international cooperation plays an important role

Farmyard manure, plant based organic fertilisers, inorganic fertiliser - which sustains soil organic matter best?

Legume biomass or pulse meal may be considered as alternatives to farmyard manure (FYM) in organic farms with small scale animal husbandry or in stockless organic farms. From 1996 a field trial was established on a poor sandy soil to compare plant based organic fertilisers, FYM and inorganic fertilisers, each applied at 100 kg ha-1 N. Additionally, FYM was tested at a higher rate of 170 kg ha-1 N. Average soil organic carbon content in topsoil (Corg) of the last crop rotation period (2002-05) is compared to that in 1996. Corg remained at the same level of 0.78 % only with FYM, while plant based and inorganic fertiliser decreased carbon contents to 0.74 and 0.72 % Corg, respectively. The higher FYM rate increased Corg up to 0.84 %. Based on these results, for soil organic matter maintenance, plant based organic fertilisers can not be recommended generally

What will long-term experiments deliver? Key results of 12 experiments on different continents.

Twelve long-term experiments have been used to describe the main management effects of organic farming systems. The experiments were mostly used to compare various types of organic and conventional cropping systems, or to study fertilisation effects. The multi-year perspective was particularly important to reveal that soil biological parameters developed better and crop yields declined less under poor growth conditions in the organic treatments. Improved co-operation of researchers involved in long-term experiments is now occurring and this will lead to more effective use of data

The well-proportioned farm organism. Just a pleasing image of a mixed farming system or rather a basic requirement for functioning organic husbandry?

The basic references and textbooks of organic farming describe this agricultural method as aiming at and using the benefits of a certain farm structure. Similar concepts and ideas of a farm have been described both by the pioneers of organic farming and by the pioneers of agricultural sciences, although using various terms: agricultural individuality (Steiner in 1924), self-sufficient organic whole (Lord Northbourne in 1940), the proportioned farm (Young in 1770), the farm organism (Koepf in 1976), the branches of a farm are like organs in a body (Aereboe in 1920) having a certain size and being dependent from each other (Brinkmann in 1922). The various terms, ideas and aspects are explained and compared with each other. In the 1970s and 1980s, some decades later than most of these references have been published, scientific activities called ecosystem research have been undertaken to investigate the structures and processes in natural or almost natural ecosystems as well as in agricultural ecosystems. Particularly, the effects and the significance of human impact (e.g. tillage, fertilization, plant protection) as regards structure, functioning and long-term stability or productivity of agroecosystems have been investigated. These results considered in the light of experiences gained in both organic and conventional farming practice can explain the linkage between structures and functions of a farm, i.e. why not only a certain diversity but also a ceratin set of operation (“impacts”) is necessary for the long-term fertility and sustainability of a farm if it is managed organically. Different, partly the opposite consequences can be observed with the specialisation versus the diversification of the farm organism. The effects of agronomic tools and techniques mainly depend on whether they support the ability of self-regulation in agroecosystems or they act as an external (anthropogenic) regulation, as different types of feedback can be provoked in the system. The paper is a contribution to the general concept of organic farming and to the present tendency in organic farming practice to accept more simple, specialized farms

Manure fertilization for soil organic matter maintenance and its effects upon crops and the environment, evaluated in a long-term trial

The effects upon soil organic matter and crop yield of applying farmyard manure, both with and without biodynamic preparations, as compared to treatments receiving mineral fertilizer (and straw) have been studied in a field trial starting in 1980. The site has a sandy orthic luvisol, 590 mm precipitation per year and 9.5̊ C annual mean temperature. Since 1985/86, crop rotation is red clover, spring wheat, potatoes and winter rye. Soil organic matter (SOM) content in the topsoil has been found to be higher with manure than with mineral fertilization. The highest SOM content of 1.00 % Corg has been observed in the treatment with biodynamic preparations. Increasing applications gave higher SOM contents only with manure, but not with mineral fertilization. SOM levels in all treatments have been fairly constant for more than 10 years. Crop yield does not show the same pattern as SOM content. Winter rye has 33 % higher yields (37.7 instead of 28.3 dt ha-1) and potatoes have 10 % higher yields (271 instead of 247 dt ha-1) with mineral as compared to manure fertilization. Spring wheat has the same yield with all types of fertilizer (approx. 40 dt ha-1). Biodynamic preparations increased potato yields by 15 dt ha-1 (6%) on average over all years. In spring wheat yield stability is greater, i.e. fluctuation over the years is smaller, with manure than with mineral fertilization

Ertrag und Qualitätseigenschaften von Sommerweizen und Kartoffeln bei organischer Düngung tierischer Herkunft (Rottemist) und pflanzlicher Herkunft (Ackerbohnenschrot)

In ökologischen Betrieben auf ertragsschwachen Standorten (z.B. sandige Böden, trockenes Klima) ist der Umfang des Tierbestandes häufig dadurch begrenzt, dass unter diesen Standortbedingungen nur eine limitierte Menge Futter erzeugt werden kann. Oft wirtschaften solche Betriebe vollständig viehlos. Die positiven Wirkungen von Stallmist sind somit nur bedingt oder überhaupt nicht nutzbar. Pflanzliche organische Dünger, wie z.B. Leguminosen-Blattmasse oder Körnerleguminosen-Schrote, könnten hier eine Alternative sein, wobei deren Effekte auf Ertrag und Qualität der Pflanzen sowie auf die Humusentwicklung der Böden im Vergleich zu Stallmist genau geprüft werden sollten. Dies war die Zielsetzung unseres Projektes. Am Beispiel von Ackerbohnenschrot wurde in einem Langzeitversuch, der seit 1996 betrieben wird, die Wirkung beider Düngerarten, jeweils mit einem Gesamtstickstoffgehalt von 100 kg ha-1, auf Sommerweizen (in 2004) und Kartoffeln (in 2005) verglichen. Zusätzlich waren Stallmistvarianten mit einer höheren Aufwandmenge (170 kg ha-1 N) und eine Mineraldüngervariante (100 kg ha-1 N) angelegt. Die organischen Dünger wurden jeweils mit und ohne Anwendung der biologisch-dynamischen Präparate eingesetzt. Im Vergleich zur Rottemistvariante war mit Ackerbohnenschrot • der Corg-Gehalt des Bodens signifikant niedriger, sein Magnesiumgehalt tendenziell geringer; • die Nitratgehalte im Boden zeigten keinen Unterschied; • die Kartoffel-Erträge waren gleich; Weizen ergab mit Ackerbohnenschrot (ohne Präparate) 4 dt ha-1 Mehrertrag bei niedrigerem Rohprotein- und Klebergehalt; • die Asche- und Kaliumgehalte der vegetativen Pflanzenmasse (Stroh, Kartoffelknollen) waren geringer; • die Zerfallsneigung der Kartoffeln (Extinktion des Extraktes) war höher. Aufgrund der genannten Nachteile kann vorläufig keine allgemeine Empfehlung für Ackerbohnenschrot ausgesprochen werden. Ansatzpunkte zur weiteren Erforschung der Problematik werden aufgezeigt

Dauerversuche Darmstadt - Die organische Substanz des Bodens unter Einfluss von Stallmistdüngung und biologischen Präparaten

Der Beitrag gibt eine Übersicht zu den bodenbiologischen Resultaten des Versuches und der Bedeutung der Stallmistdüngung und Präparateanwendung für die Humusversorgung und Pflanzenentwicklung. Insbesondere in trockenen und schwierigen Jahren sind die Erträge in den humusreicheren Rottemistvarianten höher als in den Vergleichsvarianten mit Mineraldüngung. In der Stallmistvariante mit Präparatezugabe konnte eine größere, stärker verzweigte Wurzelmasse festgestellt werden