Long‐term effects of compost amendment of soil on functional and structural diversity and microbial activity

Abstract

We studied the effects of applying different composts (urban organic waste, green waste, manure and sewage sludge), mineral fertilizer and compost plus mineral fertilizer on chemical, biological and soil microbiological parameters over a 12-year period. The organic C and total N levels in soils were increased by all compost and compost + N treatments. Microbial biomass C was significantly (P £ 0.05) increased for some compost treatments. In addition, basal respiration and the metabolic quotient (qCO 2 ) were significantly higher in all soils that had received sewage sludge compost. The Shannon diversity index (H), based on community level physiological profiling, showed a higher consumption of carbon sources in soils treated with compost and compost + N compared with the control. The utilization of different guilds of carbon sources varied amongst the treatments (compost, compost + N or mineral fertilizer). Cluster analysis of polymerase chain reaction-denaturing gradient gel electrophoresis patterns showed two major clusters, the first containing the mineral fertilization and compost treatments, and the second, the composts + N treatments. No differences in bacterial community structure could be determined between the different types of compost. However, the results suggest that long-term compost treatments do have effects on the soil biota. The results indicate that the effects on the qCO 2 may be due to shifts in community composition. In this study, it was not possible to distinguish with certainty between the effects of different composts except for compost derived from sewage sludge.

Substrate-induced volatile organic compound emissions from compost-amended soils

“…The site is part of a crop rotation fertilisation experiment (grain maize, summer wheat and winter barley) that was started in 1991 by the Austrian Agency for Health and Food Safety. The soil is a loamy silt with a pH of 6.8 (±0.4), an organic matter content of 1.9% (Ros et al 2006a;Innerebner et al 2006) and a water holding capacity of 0.5 g H 2 O per gram dry soil. Soil characteristics and heavy metal contents are described in Ros et al (2006a).…”

“…The soil is a loamy silt with a pH of 6.8 (±0.4), an organic matter content of 1.9% (Ros et al 2006a;Innerebner et al 2006) and a water holding capacity of 0.5 g H 2 O per gram dry soil. Soil characteristics and heavy metal contents are described in Ros et al (2006a). Compost amendment takes place once a year in spring or autumn, followed by tilling (20 to 40 cm depth) shortly before crop planting.…”

“…Besides this, conversion of organic residues such as sewage sludge, green cut, organic wastes or animal manure into useable composts reduces the amount of waste deposed into landfill sites, thereby improving the cycling of matter. Besides these known benefits, soil compost and fertiliser amendments affect the soil microbial community composition and activity in different ways, as has been shown by Innerebner et al (2006) and Ros et al (2006a, b). Microbiological tools range from conventional cultivation approaches to molecular techniques, each of them with its own advantages, biases and limitations.…”

“…In particular, soils with a low soil organic matter (SOM) content (e.g. below 2%) benefit from organic matter input (Lal 2005;Roldan et al 2005;Ros et al 2006a). Besides this, conversion of organic residues such as sewage sludge, green cut, organic wastes or animal manure into useable composts reduces the amount of waste deposed into landfill sites, thereby improving the cycling of matter.…”

“…To maintain plant nutrient contents, in most cases, mineral fertilisers are used, whilst the role of soil organic matter as an essential determinant of soil fertility and stability is often underestimated (Ros et al 2006a). To build up soil organic matter in arable soils-a process much slower than its degradation-modern farming approaches include a sustainable management of soils to maintain the longterm productivity.…”