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Root biomass is one of the most relevant root parameters for studies of plant response to environmental change, soil carbon modeling or estimations of soil carbon sequestration. A major source of error in root biomass quantification of agricultural crops in the field is the presence of extraneous organic matter in soil: dead roots from previous crops, weed roots, incorporated above ground plant residues and organic soil amendments, or remnants of soil fauna. Using the isotopic difference between recent maize root biomass and predominantly C3-derived extraneous organic matter, we determined the proportions of maize root biomass carbon of total carbon in root samples from the Swiss long-term field trial “DOK.” We additionally evaluated the effects of agricultural management (bio-organic and conventional), sampling depth (0–0.25, 0.25–0.5, 0.5–0.75 m) and position (within and between maize rows), and root size class (coarse and fine roots) as defined by sieve mesh size (2 and 0.5 mm) on those proportions, and quantified the success rate of manual exclusion of extraneous organic matter from root samples. Only 60% of the root mass that we retrieved from field soil cores was actual maize root biomass from the current season. While the proportions of maize root biomass carbon were not affected by agricultural management, they increased consistently with soil depth, were higher within than between maize rows, and were higher in coarse (>2 mm) than in fine (≤2 and >0.5) root samples. The success rate of manual exclusion of extraneous organic matter from root samples was related to agricultural management and, at best, about 60%. We assume that the composition of extraneous organic matter is strongly influenced by agricultural management and soil depth and governs the effect size of the investigated factors. Extraneous organic matter may result in severe overestimation of recovered root biomass and has, therefore, large implications for soil carbon modeling and estimations of

To increase nutrient use efficiency and reduce nutrient losses are key aspects for sustainable agriculture. Arbuscular mycorrhizal fungi (AMF) are an import and widespread group of plant-symbiotic soil fungi. Here we investigate the role of those soil microorganisms, for effective nutrient recycling. We conducted greenhouse and lysimeter experiments to compare the cycling of important plant nutrients in systems with high and low abundance of AMF. AMF increased plant N nutrition, reduced leaching losses of mineral N, and prevented emissions of N2O, an important greenhouse gas. The results show the importance of AMF for an effective nutrient management. Farmers should implement strategies to promote AMF in the soil, as they are an indispensable compound of sustainable agriculture.

In a large scale field experiment near Lucerne (Switzerland) the effect of integrated and organic farming systems on soil microbial parameters was investigated. Three farming systems, IP intensive, IP extensive and organic farming (“Bio”) were com-pared on six plots during 18 years. The six year crop rotation with two years of ley (grass-clover mixture) was identical for all treatments, as was soil tillage, except that tillage in IP extensive was switched to non-inversion tillage starting in 2003. Soil sam-ples from 0 to 20 cm depth were taken in spring, between 1993 to 1996 every year and after 1998 every second year. The samples were analysed for soil microbial biomass (substrate induced respiration SIR and since 2002 chloroform fumigation extraction CFE), soil respiration and nitrogen mineralisation. All parameters showed clear and stable differences between plots, depending on soil characteristics. Although significant differences between farming systems in single plots or for single parame-ters occurred, there could not be found any overall significant differences between the three farming systems. Although this result is contradictory to findings in the literature, it is confirmed by other investigations in Switzerland. It may be explained by the fact that both IP as well as the organic farming system had the same crop rotations and both got organic manure, as it is common agricultural practice in Switzerland.

The aim of this study was to evaluate the interaction between yield levels of nonleguminous crops and soil organic matter (SOM) under the specific conditions of organic and conventional farming, respectively, and to identify implications for SOM management in arable farming considering the farming system (organic vs. conventional). For that purpose, correlations between yield levels of nonlegume crops and actual SOM level (Corg, Nt, Chwe, Nhwe) as well as SOM-level development were examined including primary data from selected treatments of seven long-term field experiments in Germany and Switzerland. Yield levels of nonlegume crops were positively correlated with SOM levels, but the correlation was significant only under conditions of organic farming, and not with conventional farming treatments. While absolute SOM levels had a positive impact on yield levels of nonlegumes, the yield levels of nonlegumes and SOM-level development over time correlated negatively. Due to an increased demand of N from SOM mineralization, higher yield levels of nonlegumes obviously indicate an increased demand for OM supply to maintain SOM levels. Since this observation is highly significant for farming without mineral-N fertilization but not for farming with such fertilization, we conclude that the demand of SOM-level maintenance or enhancement and thus adequate SOM management is highly relevant for crop production in organic farming both from an agronomical and ecological point of view. Under conventional management, the agronomic relevance of SOM with regard to nutrient supply is much lower than under organic management. However, it has to be considered that we excluded other possible benefits of SOM in our survey that may be highly relevant for conventional farming as well.

The effect of integrated and organic farming on crop yield as well as on environmental and economic performance was investigated in a large scale field experiment near Lucerne (Switzerland), which was running for 18 years. Crop yield in organically managed fields was, depending on crop species, between 3% and 36% lower compared to conventionally managed fields. Only slight variations in crop quality were observed between the farming systems, probably as a result of the high nitrogen mineralization potential of the soils in this experiment. Our results show that organic farming on fertile soils provides good yields and is – under the given Swiss agricultural policy – economically beneficial.

Effective microorganisms® (EM) is a microbial inoculant promoted to stimulate plant growth and soil fertility in agriculture. In our study we investigated the effects of EM on crop yields and soil microbial parameters in a 4-year field experiment under organic management (2003–2006) in Zurich, Switzerland. Treatments of the EM preparations (i) the spraying agent EMA, (ii) EMA with the EM enriched organic substrate Bokashi and (iii) EMA with Bokashi and farmyard manure were applied in each year. As controls to treatments (i)–(iii) the same treatments were included with sterilised EM preparations and a control without EM application. Crop yields in each year and the soil microbiological parameters soil respiration, microbial biomass (SIR, CFE), dehydrogenase activity and microbial community structure (RISA, CLSU) were determined in spring and autumn 2005 and spring 2006. In laboratory incubation experiments cellulose degradation, N mineralisation potential and N mineralisation from added substrate were determined. The EMA application as spraying agent alone (treatment (i)) showed no significant differences to the untreated control (treatment without EM application) for any of the investigated parameters. Significant differences to the untreated control for crop yields and soil microbial parameters were found if Bokashi was applied in addition to EMA ((ii) and (iii)). However, these differences were not consistent throughout the parameters and sampling times. Treatments with living EM compared with its sterilised control treatments showed no differences on any of the parameters. This indicates that the small effects observed were not caused by the EM microorganisms but rather by the nutrient inputs derived from Bokashi. The sampling time showed stronger effects on soil microbial biomass, soil respiration and microbial community structure when compared to the effects of the treatments. We conclude from our results that ‘Effective microorganisms’ did not improve yields a

Im DOK-Feldversuch in Therwil, Schweiz werden seit 1978 folgende landwirtschaftlichen Anbausysteme verglichen: Konventionell (CONFYM, mineralische und organische Düngung, synthetische Pflanzenschutzmittel), biologisch organisch (BIOORG, organische Düngung, mechanische Unkrautbekämpfung und biologische Krankheits- und Schädlingsbekämpfung) sowie biologisch-dynamisch (BIODYN, organische Düngung mit kompostiertem Mist, Pflanzenschutz wie BIOORG,aber ohne Cu, biologisch-dynamische Präparate).

Pseudomonas fluorescens strains are used in agriculture as plant growth-promoting rhizobacteria (PGPR). Nontarget effects of released organisms should be analyzed prior to their large-scale use, and methods should be available to sensitively detect possible changes in the environments the organism is released to. According to ecological theory, microbial communities with a greater diversity should be less susceptible to disturbance by invading organisms. Based on this principle, we laid out a pot experiment with field-derived soils different in their microbial biomass and activity due to long-term management on similar parent geological material (loess). We investigated the survival of P. fluorescens CHA0 that carried a resistance toward rifampicin and the duration of potential changes of the soil microflora caused by the inoculation with the bacterium at the sowing date of spring wheat. Soil microbial biomass (C(mic), N(mic)) basal soil respiration (BR), qCO(2), dehydrogenase activity (DHA), bacterial plate counts, mycorrhiza root colonization, and community level substrate utilization were analyzed after 18 and 60 days. At the initial stage, soils were clearly different with respect to most of the parameters measured, and a time-dependent effect between the first and the second set point were attributable to wheat growth and the influence of roots. The effect of the inoculum was small and merely transient, though significant long-term changes were found in soils with a relatively low level of microbial biomass. Community level substrate utilization as an indicator of changes in microbial community structure was mainly changed by the growth of wheat, while other experimental factors were negligible. The sensitivity of the applied methods to distinguish the experimental soils was in decreasing order N(mic), DHA, C(mic), and qCO(2). Besides the selective enumeration of P. fluorescens CHA0 rif(+), which was only found in amended soils, methods to distinguish the inocu

Organic farming systems often comprise crops and livestock, recycle farmyard manure for fertilization, and preventive or biocontrol measures are used for plant protection. We determined indicators for soil quality changes in the DOK long-term comparison trial that was initiated in 1978. This replicated field trial comprises organic and integrated (conventional) farming systems that are typical for Swiss agriculture. Livestock based bio-organic (BIOORG), bio-dynamic (BIODYN) and integrated farming systems (CONFYM) were compared at reduced and normal fertilization intensity (0.7 and 1.4 livestock units, LU) in a 7 year crop rotation. A stockless integrated system is fertilized with mineral fertilizers exclusively (CONMIN) and one control treatment remained unfertilized (NOFERT). The CONFYM system is amended with stacked manure, supplemental mineral fertilizers, as well as chemical pesticides. Manure of the BIOORG system is slightly rotted and in BIODYN it is composted aerobically with some herbal additives. In the third crop rotation period at normal fertiliser intensity soil organic carbon (Corg, w/w) in the plough layer (0–20 cm) of the BIODYN system remained constant and decreased by 7% in CONFYM and 9% in BIOORG as compared to the starting values. With no manure application Corg-loss was severest in NOFERT (22%), followed by CONMIN together with the systems at reduced fertiliser intensity (14–16%). Soil pH tended to increase in the organic systems, whereas the integrated systems had the lowest pH values. At the end of the third crop rotation period in 1998 biological soil quality indicators were determined. Compared to soil microbial biomass in the BIODYN systems the CONFYM soils showed 25% lower values and the systems without manure application were lower by 34%. Relative to the BIODYN soils at the same fertilization intensity dehydrogenase activity was 39–42% lower in CONFYM soils and even 62% lower in soils of CONMIN. Soil basal respiration did not differ betwe

Organic farming systems often comprise crops and livestock, recycle farmyard manure for fertilization, and preventive or biocontrol measures are used for plant protection. We determined indicators for soil quality changes in the DOK long-term comparison trial that was initiated in 1978. This replicated field trial comprises organic and integrated (conventional) farming systems that are typical for Swiss agriculture. Livestock based bio-organic (BIOORG), bio-dynamic (BIODYN) and integrated farming systems (CONFYM) were compared at reduced and normal fertilization intensity (0.7 and 1.4 livestock units, LU) in a 7 year crop rotation. A stockless integrated system is fertilized with mineral fertilizers exclusively (CONMIN) and one control treatment remained unfertilized (NOFERT). The CONFYM system is amended with stacked manure, supplemental mineral fertilizers, as well as chemical pesticides. Manure of the BIOORG system is slightly rotted and in BIODYN it is composted aerobically with some herbal additives. In the third crop rotation period at normal fertiliser intensity soil organic carbon (Corg, w/w) in the plough layer (0–20 cm) of the BIODYN system remained constant and decreased by 7% in CONFYM and 9% in BIOORG as compared to the starting values. With no manure application Corg-loss was severest in NOFERT (22%), followed by CONMIN together with the systems at reduced fertiliser intensity (14–16%). Soil pH tended to increase in the organic systems, whereas the integrated systems had the lowest pH values. At the end of the third crop rotation period in 1998 biological soil quality indicators were determined. Compared to soil microbial biomass in the BIODYN systems the CONFYM soils showed 25% lower values and the systems without manure application were lower by 34%. Relative to the BIODYN soils at the same fertilization intensity dehydrogenase activity was 39–42% lower in CONFYM soils and even 62% lower in soils of CONMIN. Soil basal respiration did not differ betwe