Effecten van gewassen en gangbare landbouwkundige handelingen op specifieke groepen van micro-organismen

Voor deze literatuurstudie zijn mycorrizha, rhizobia, pseudomonaden, acitinomyceten en nitrificerende bacterien geselecteerd en betokken bij de volgende functies in de bodem; afbraak van organische stof, instandhouden van de bodemvruchtbaarheid en bodemstructuur en de bescherming tegen plantenziekten. Voor de teelt van aardappel, koolzaad, snijmais, suikerbiet en tarwe. Dit voor de milieurisicoanalyse van effecten genetisch gemodificeerde planten op het leven in de bodem

Nematode-based risk assessment of mixture toxicity in a moderately polluted river floodplain in The Netherlands

Heavy metal polluted soils usually contain mixtures of different metals, whereas legislation is derived from concentrations of individual metals. The mixture toxicity of the Dutch floodplain Afferdensche and Deestsche Waarden was estimated to be high (msPAF ranged from 67¿94%). Analyses of nematode community based bioindicators (Maturity Index, taxonomic diversity, trophic groups, multivariate analysis, DoFT-sentinels) were used to determine the ecological effects of the mixture toxicity in the floodplain soil. None of the indices indicated direct effects of heavy metals on the nematode community. This can be explained by the high adsorption of heavy metals on organic matter and clay particles resulting in a low bioavailability, and questions the estimation of the toxicity based on total concentrations of heavy metals in such environments. The nematode fauna showed great seasonal variation, which most probably was related to the temporal inundation of the floodplain

Effects of slurry application methods on soil faunal communities in permanent grassland

We studied the effects of two slurry manure application methods, broadcasting manure slurry (MB) and manure slit injection (SMI), on soil faunal communities 1 week and 4 or 5 weeks after application in the spring of 2002 and the summer of 2003. No effect on total numbers of Enchytraeidae and nematodes was found. Enrichment opportunistic nematodes (CP1) significantly decreased in the MB treatment, resulting in a significantly higher Maturity Index. In the SMI treatment the Maturity Index was unchanged. Effects of manure application methods on earthworms depended on soil moisture and season. Under wet conditions abundance of earthworms, especially epigeic earthworms, decreased significantly in the MB treatment. In the summer of 2003 total earthworm numbers, and the fraction of epigeics, decreased after SMI. Due to the drought in this period, abundances of epigeic earthworms were already low and possible significant effects of the different manure application methods were therefore hard to interpret

Nematode-based risk assessment of mixture toxicity in a moderately polluted river floodplain in The Netherlands

Heavy metal polluted soils usually contain mixtures of different metals, whereas legislation is derived from concentrations of individual metals. The mixture toxicity of the Dutch floodplain Afferdensche and Deestsche Waarden was estimated to be high (msPAF ranged from 67¿94%). Analyses of nematode community based bioindicators (Maturity Index, taxonomic diversity, trophic groups, multivariate analysis, DoFT-sentinels) were used to determine the ecological effects of the mixture toxicity in the floodplain soil. None of the indices indicated direct effects of heavy metals on the nematode community. This can be explained by the high adsorption of heavy metals on organic matter and clay particles resulting in a low bioavailability, and questions the estimation of the toxicity based on total concentrations of heavy metals in such environments. The nematode fauna showed great seasonal variation, which most probably was related to the temporal inundation of the floodplain

Heavy metal concentrations in soil and earthworms in a floodplain grassland

We determined accumulated heavy metal concentrations (Cd, Pb, Cu, Zn) of earthworms in moderately contaminated floodplain soils. Both soil and mature earthworms were sampled before and after flooding and earthworm species were identified to understand species specific differences in bioconcentration. Accumulated metal concentrations in floodplain earthworms differed before and after flooding. Differences in uptake and elimination mechanisms, in food choice and living habitat of the different earthworm species and changes in speciation of the heavy metals are possible causes for this observation. Regression equations taken from literature, that relate metal accumulation by earthworms in floodplains as a function of metal concentration in soil, performed well when all species specific data were combined in an average accumulation, but did not address differences in accumulation between earthworm species. The accumulation of metals by earthworms is species dependent and affected by flooding