Influence of inorganic and organic fertilization on soil microbial biomass, metabolic quotient and heavy metal bioavailability

Abstract

We studied the long-term effects (12 years) of municipal refuse compost addition on the total organic carbon (TOC), the amount and activity of the microbial biomass (soil microbial biomass C, B(C) and metabolic quotient qCO2) and heavy metal bioavaiability in soils as compared to manuring with mineral fertilizers (NPK) and farmyard manure (FYM). In addition, we studied the relationships between among the available fraction [Diethylenetriaminopentacetic acid (DTPA) extractable] of heavy metals and their total content, TOC and B(C). After 12 years of repeated treatments, the TOC and B(C) of control and mineral fertilized plots did not differ. Soils treated with FYM and composts showed a significant increase in TOC and B(C) in response to the increasing amounts of organic C added. Values of the B(C)/TOC ratio ranged from 1.4 to 2, without any significative differences among soil treatments. The qCO2 increased in the organic-amended soil and may have indicated microbial stress. The total amounts of metals in treated soils were lower than the levels permitted by the European Union in agricultural soils. DTPA-extractable metals increased in amended soils in response to organic C. A multiple regression analysis with stepwise selection of variables was carried out in order to discriminate between the influence exerted on DTPA-extractable metals by their total content. TOC and B(C). Results showed that each metal behaved quite differently, suggesting that different mechanisms might be involved in metal bioavailability

Contamination of the soil and water environment by heavy metals in the former mining area of Rudňany (Slovakia)

“…No correlation between organic carbon and heavy metal content was confirmed. Consistent with our results, Leita et al (1999) reported that organic carbon probably does not reflect the heavy metal soil contamination. Wang et al (2007) found nonsignificant correlation between organic carbon and soil enzymes, which was probably due to the quality of the organic inputs into the soil.…”

Effect of long-term organic amendments on chemical and microbial properties of a luvisol

“…Confirming the results of Kowalczyk and Schröder (1988) we found a positive correlation (r = 0.73) between dehydrogenase activity and microbial biomass. However, we cannot confirm that heavy metals, which are the most important inorganic pollutants added to soils with sewage and compost (Leita et al 1999), decrease the turnover rate of organic matter, presumably because of the inhibitory effects on microbial biomass and enzyme activity (Chandler et al 1995). …”

“…Influence of long-term application of organic wastes and mineral N fertilizer on soil pH, total N, C org , C mic and C mic /C org (soil samples were taken from the soil layer from 0-30 cm in spring 2006) clearly demonstrate that there were positive effects of organic amendments on microbiological soil parameters, it may be concluded that plant growth in our experiment was inhibited by the increased heavy metal content (Werner et al 1987). For this reason organic amendments must be viewed cautiously because of the increase of the soil content of toxic metals (Leita et al 1999). …”

Succession of microbiota estimated by phospholipid fatty acid analysis and changes in organic constituents during the composting process of rice straw

“…One of the most common applied is rice straw (RS) compost. Although the importance of compost application for sustainable agriculture has been well documented by longterm fertilizer trials (Inoko 1984;Leita et aL 1999), little attention had been paid to the composting process from the viewpoint of soil microbiology.…”