Changes in heated and autoclaved forest soils of S.E. Australia. I. Carbon and nitrogen

Abstract

Abstract. The effect of heating and autoclaving on extractable nitrogen, N mineralisation and C metabolism was studied by heating five forest soils in the laboratory, simulating the range of effects of heat due to bushfire.

Effect of burning on soil organic matter content and N mineralization under shifting cultivation system of Karen people in Northern Thailand

“…However, when a large amount of the slashed biomass was burned as in the case of the T -100 plot, soil microbes may experience serious damage. Serrasolsas and Khanna (1995) observed a rapid recovery of microbial biomass after burning at less than 120T but no response at 250T in their laboratory burning experiments. The content of NH 4 -N decreased and that of N0 3 -N increased (Fig.…”

“…1, in which the difference in the increase of the NH 4 -N content by burning was relatively small among the soils from T -0 to T -50. Serrasolsas and Khanna (1995) described the reasons for the increase in the amounts of easily extractable C and N as follows, 1) lysis of microbial cells, 2) increase in the solubility of both non-microbial organic N and inorganic forms of N, and 3) partial ashing of organically bound nutrients. Russell et al (1974) concluded that flush of NH 4 -N during soil heating at 100 to 230'C could be ascribed to the thermal decomposition of organic matter or killed microbes, mainly secondary amide groups and amino acids.…”

“…However, in the case of shifting cultivation for daily subsistence, the effects have not been thoroughly studied, for example, in India (Ramakrishnan 1992) and in Thailand (Tulaphitak et al 1985a, b). The burning effects related to N dynamics in soils can be divided into two mechanisms: 1) flush of NH 4 -N during burning, which can be ascribed to the thermal decomposition of soil organic matter (Russell et al 1974) in addition to the external N input through ash addition and 2) stimulation of N mineralization after burning, which can be ascribed to the increase in the amount of labile organic N fractions through the changes in the soil organic matter properties and death of soil microbes by heating (Serrasolsas and Khanna 1995). However, many of the studies on burning were carried out in the laboratory, while studies in situ have tended to focus on the N dynamics or mineralization process from several months to several years after burning.…”

Steam treatment of surface soil: how does it affect water-soluble organic matter, C mineralization, and bacterial community composition?

“…Indeed, fumigation methods (Ladd and Amato 1988) as well as autoclaving (Serrasolsas and Khanna 1995) were shown to increase potentially bioavailable C and N by releasing water-soluble compounds. Also, the potential release of soil components in water may affect soluble compounds as well as colloids involved in soil aggregation.…”

“…Also, the potential release of soil components in water may affect soluble compounds as well as colloids involved in soil aggregation. Release of soil organic components may supply substrates for microbial growth, although contrasting results showed either immediate use by microorganisms (Serrasolsas and Khanna 1995) or use after a lag phase (Leinweber et al 1995). Moreover, the water-extractable organic matter (WEOM) quality may differ among soil types and managements (Chantigny 2003).…”