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Book of Abstracts

11th IFOAM
Scientific Conference
11-15 August 1996
Copenhagen, Denmark


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Bio Waste Compost and Soil Microbiology E3

Schwaiger, E.

Ludwig Boltzmann Institute for Biological Agriculture and Applied Ecology, 1110 Vienna

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The level of soil enzyme activity provides information about microbial growth and development. This study presents data from the effects of compost combined with mineral N fertilizer on soil microorganism.

In a four year field trial the following fertilizer combinations were compared to an unfertilized control: 1) BK3 = biowaste compost (45 t.ha-1); 2) N1BK3 = biowaste compost plus N (25 resp. kg.ha-1); 3) N1BK2 = biowaste compost (15 t.ha-1) plus N; 4) N3 = N fertilizer (75 rep. 120 kg.ha-1)

The compost was applied every year in autumn. The soil samples were taken in spring from the top layer (0-20 cm), sieved (4 mm) and stored at - 20 oC prior to analyzation. The samples for the estimation of soil aggregate stability (SAS) were air dried and sieved (1-2 mm). SAS demonstrates the resistance of particles against the disruptive force of water. The soil enzyme were chosen from the N, C and P cycle of nutrients (urease, protease, B-glucosidase and alkaline phosphatase); substrate induced respiration (SIR) as characteristic of soil microbial biomass. The data were subjected to Analysis of Variance and Comparison of Mean.

After high activity in 1994 the following years SIR showed a decrease. Finally compost and compost combined fertilisation increased soil microbial activity compared with N fertilisation and the control sample. Trials with compost also provided for higher SAS values. B-glucosidase and alkaline phosphatase did not show consistent behaviour patterns but appeared to be more influenced by crop rotation. Urease and particularly protease showed a decrease during the years of investigation. This was due to climatic effects, crop rotation and - in the case of protease - presumably difficulties in reducing high moleculare compounds of compost. However, in 1996 the significantly highest urease and protease activity were noted in compost fertilized plots. Both enzymes were well adapted to total N and organic C.

Murer, E.J.; Baumgarten, A.; Eder, G.; Gerzabek, M.H.; Kandeler, E.; Rampazzo, N. (1992): An improved sieving machine for estimation of soil aggregate stability (SAS). Geoderma: vol. 56, pp 539-547.

Schinner, F.; Íhlinger, R.; Kandeler, E.; Margesin, R. (1993): Bodenbiologische Arbeitsmethoden. Springer, Berlin.