Effects of soil management history on the rate of organic matter decomposition

Abstract

ÐIn a sustainable agriculture farming systems experiment, soils managed under organic farming practices had greater microbial abundance and activity, and higher numbers of bacterial-feeding nematodes during crop growth, than those managed under conventional farming practices. We tested rates of organic matter decomposition in the two soils and monitored the abundance and activity of soil biota during the decomposition process. Dierences in soil biology between soils from organic and conventional farming systems did not persist when soils were amended with organic matter and maintained under similar conditions. Microbial communities in soil from the conventional system were sucient and active enough to respond to organic inputs. There were minimal dierences in the ability of the microbial communities of the two soils to decompose organic residues. However, when soils were removed from the ®eld at dierent times, cover crop decomposition rates were more consistent in the organic soils, suggesting a greater abundance and diversity of the microbial community in those soils. Microbial activity was most suppressed when ®eld soils were dry but responded to organic matter amendment very rapidly when favorable moisture contents were restored. The pattern of microbial activity in both organic and conventional soils following organic matter incorporation consisted of a 100 h activity phase and then a gradual decline to a relatively constant stasis phase.

Net N immobilisation during the biodegradation of mucilage in soil as affected by repeated mineral and organic fertilisation

“…Organic fertilizers commonly favour accumulation of soil organic matter (SOM) (Gunapala et al 1998;Munoz et al 2003) and they improve the quality of SOM by increasing the labile fraction (Nardi et al 2004;Blair et al 2006a, b). Organic fertilizers also improve the soil structural conditions through the formation of stable macroaggregates with a high microbial activity (Aoyama et al 2000).…”

Comparative Analysis of Environmental Variability and Fungal Community Structure in Soils between Organic and Conventional Commercial Farms of Cherry Tomato in Japan

“…Therefore, the microbial community structure should provide essential information for biological evaluation of the difference between ORG and CNV farming systems. In this context, microbial characteristics such as microbial biomass 11,25,32,44) , respirations 13,22) , enzyme activity 22) , and phospholipid fatty acids 4,42) were analyzed 19) . Although numerous studies on the differences between ORG and CNV management have been conducted, reports on microbial community structure are limited to a few papers on the bacterial community 34,35,44) .…”

Carbon and nitrogen dynamics in topsoils along forest conversion sequences in the Ore Mountains and the Saxonian lowland, Germany

“…Whether soils are a net carbon source or sink depends predominantly on their microbial activity, amount of litter fall and management practices (Bouwman and Leemans 1995;Fearnside and Barbosa 1998;Gunapala et al 1998;Ma¨kipa¨a¨et al 1999). Generally, natural forests are believed to represent a steady C accumulation potential up to the over-mature phase (Schulze et al 2000a).…”