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The global environment is constantly changing and our planet is getting warmer at an unprecedented rate. The study of the carbon cycle, and soil respiration, is a very active area of research internationally because of its relationship to climate change. It is crucial for our understanding of ecosystem functions from plot levels to global scales. Although a great deal of literature on soil respiration has been accumulated in the past several years, the material has not yet been synthesized into one place until now. This book synthesizes the already published research findings and presents the fundamentals of this subject. Including information on global carbon cycling, climate changes, ecosystem productivity, crop production, and soil fertility, this book will be of interest to scientists, researchers, and students across many disciplines. * A key reference for the scientific community on global climate change, ecosystem studies, and soil ecology* Describes the myriad ways that soils respire and howthis activity influences the environment* Covers a breadth of topics ranging from methodologyto comparative analyses of different ecosystem types* The first existing \"treatise\" on the subject

In West Sumatra, Indonesia, a high-yield perennial rice cropping method called SALIBU was recently reported, in which the most unique feature is double cutting (DC) at harvest and after harvest. The objective of this study was to verify the ratooning rice yield under the SALIBU system in Myanmar. Two cultivation trials consisting of two cutting and three moisture treatments were conducted in 2019 and 2020. We concluded that double cutting had no positive effect on grain yield and regeneration rate compared with single cutting (SC). For the cutting regime, significant results were detected in the ratoon crops on yield components, but all of these were negative effects of DC, and were statistically lower than those of SC. On the other hand, a significant positive effect of moisture regime on grain yield in all ratoons was observed. The grain yield of the dry regime was significantly increased by 69% compared with that of the saturated regime. Soil oxidation conditions during the initial growth period of ratoons could contribute to the improved yield performance of the ratoons.

Mangrove forests as a coastal ecosystem can remove N in sewage effluent through the denitrification in mangrove soils. This research was designed to evaluate effects of temperature, salinity, nitrate, and organic carbon (OC) on denitrification enzyme activity (DEA). The test was conducted using an acetylene inhibition method in controlled laboratory conditions. Results showed potential DEA was lowest in soil collected from the site with lowest amount of soil OC and total nitrogen. With increased soil temperature (15–25 °C), the DEA was enhanced by 2.5–5 times. Soil potential DEA was negatively correlated to salinity (0–60 psu). The potential DEA at the highest experimental salinity (60 psu) was still 3 times higher than the field DEA, implying that salinity has less effect on soil denitrification in the field. The potential DEA was stimulated by labile OC such as glucose and sucrose, but it was not affected by the addition of lactose, acetate and mannitol. Overall, this study showed that mangrove forest soils can reach maximum rate of treating NO 3 − from sewage effluent if the inflow NO 3 − concentration is < 3 mM. The treatment efficiency of NO 3 − appears to vary, depending on availability of labile OC, soil redox, and temperature.

Methane emissions from plants in wetlands are mainly due to internal transport, from the anoxic soil layers where methane is produced, to the atmosphere. This pathway has not yet been clearly demonstrated for upland forest vegetation, where methane can be produced in deep soil layers. We developed a new method to trace methane transfer from the deep soil. We conducted a 13 CH 4 pulse labelling at 40-cm soil depth and then monitored 13 CH 4 in the upper horizons, at the soil surface (with or without understorey vegetation) and emitted by tree stems until the total disappearance of the labelled gas. Most of the injected 13 CH 4 was oxidized in the soil despite high soil water content. The understorey vegetation did not contribute to 13 CH 4 emission by the soil. We prove that tree stems can emit methane produced in an upland forest soil, even when the said soil is a net methane sink. We conclude that pulse labelling with 13 CH 4 and tracing by laser-based spectrometry is a promising tool approach to study the transport of methane from production to emission.

Researchers studying the chemistry of soil systems may be interested in documenting the oxidation–reduction potential (Eh) for a variety of purposes, and this is often accomplished by measuring the Eh using platinum (Pt) electrodes in conjunction with a reference electrode and a voltmeter. It has been shown that Eh values obtained when using high resistance research grade instruments often are much different from values measured using standard multimeters. This difference appears to be a function of the input resistance, with the low resistance multimeters allowing a higher current to flow during measurement which alters the electrochemical environment causing the voltage to drift. The objectives of this paper are (i) to report on a device which when attached to a low resistance multimeter facilitates the accurate measurement of soil redox potential, and (ii) to better understand the nature of the drift observed when measurements are made using a standard multimeter. Redox potentials were measured with Pt and calomel electrodes in soil mesocosms using a research grade voltmeter and a standard multimeter, with and without an inexpensive device that effectively increased the input resistance of the multimeter to 1 Tohm. The device was constructed using a TL082 wide bandwidth dual JFET input operational amplifier which effectively raised the input resistance from 10 Mohm to approximately 1 Tohm. When a small correction factor was applied to account for the internal offset error from the amplifier, the Eh data recorded using the modified multimeter were essentially identical to those collected using higher end, research grade instruments (n = 162; Y = 0.9996X– 0.09; r2 = 1.0000). Depending on the pH of the system and the type of reference electrode used, and the redox couple of interest, Eh data collected using standard multimeters could lead to erroneous conclusions regarding whether a soil is oxidized or reduced.

A biofilter made using volcanic pumice soil from a landfill in Taupo, New Zealand has been found to mitigate CH 4 emissions from New Zealand dairy effluent ponds. However, the biofilter after drying out following almost 5 years of use removed little or no CH 4 . Furthermore, H 2 S present in the biogas (from the dairy effluent ponds) had increased the acidity (pH) in the soil biofilter from 5.2 to 3.72 during this 5-year period. In this study, we adjusted the soil moisture to 60 % water-holding capacity (WHC) and investigated the CH 4 -oxidising capacity of a reconstituted acidic soil biofilter operating at low pH (3.72) and characterised the abundance and diversity of methane-oxidising bacteria (MOB) using quantitative polymerase chain reaction (qPCR) and terminal-restriction fragment length polymorphism (T-RFLP). The acidic soil biofilter achieved a maximum CH 4 removal rate of 30.3 g m –3  h –1 . Both types I and II MOB communities, along with some uncultured novel MOB strains or species in the biofilter column, were present. Among these, Methylocapsa -like type II methanotrophs were significantly more prominent than the other MOB. Other MOB, Methylococcus (type I), Methylobacter/Methylomonas/Methylosarcina (type I) genera, Methylosinus and Methylocystis (type II), were least abundant. During the 90-day study, the population of Methylocapsa -like MOB increased 4-fold, demonstrating the ability of these soil microorganisms to grow under acidic pH conditions in the biofilter, whereas the populations of type I MOB remained stable, and the populations of type II MOB (except Methylocapsa ) decreased. Our results indicated that (i) a soil biofilter can effectively regain efficiency if sufficient moisture levels are maintained, regardless of the soil acidity; (ii) changes in the MOB population did not compromise the capacity of the volcanic pumice soil to oxidise CH 4 ; (iii) the more acidic environment (pH 3.72) tends to favour the growth and activity of acid loving Methylocapsa -like MOB while being detrimental to the growth of Methylobacter / Methylocystis / Methylococcus group of MOB; and (iv) novel species or strains of uncultured Methylomicrobium / Methylosarcina / Methylobacter (type I MOB) could be present in the soil biofilter. This study has revealed the MOB population changes in the biofilter with acidification did not compromise its capacity to oxidise CH 4 demonstrating that soil biofilter can operate effectively under acidic conditions.

We determined the response of terrestrial methane (CH₄) uptake to 4 years of full-factorial manipulations of precipitation and temperature in four ecosystems along a 50 km warm and dry to cold and wet climatic gradient (desert grassland, pinyon-juniper woodland, ponderosa pine forest, and mixed conifer forest). Our goals were to determine whether ecosystem-specific, intraannual, and interactive responses to altered precipitation and warming are quantitatively important. Passive collectors and interceptors increased (+50% per event) and reduced (−30% per event) the quantity of precipitation delivered to experimental plant-soil mesocosms, and downward transfer along the elevation gradient warmed mesocosms by 1.8°C on average. Methane uptake in the colder and wetter ecosystems along the gradient decreased with increasing precipitation, especially during the wet season. The warmer and drier ecosystems, however, responded more strongly to warming, exhibiting less CH₄ uptake with increasing temperature. We found no interaction between altered precipitation and warming in any ecosystem. Soil CH₄ consumption in the laboratory was a strong predictor of ecosystem differences in field CH₄ consumption, but was a poor predictor of the effects of climatic change observed in the field. Based on our results, future climate scenarios that are wet and warm will cause the largest reduction in terrestrial CH₄ uptake across ecosystem types.

For extremely ionizing radiation-resistant bacteria, survival has been attributed to protection of proteins from oxidative damage during irradiation, with the result that repair systems survive and function with far greater efficiency during recovery than in sensitive bacteria. Here we examined the relationship between survival of dry-climate soil bacteria and the level of cellular protein oxidation induced by desiccation. Bacteria were isolated from surface soils of the shrub-steppe of the US Department of Energy's Hanford Site in Washington State. A total of 63 isolates were used for phylogenetic analysis. The majority of isolates were closely related to members of the genus Deinococcus , with Chelatococcus , Methylobacterium and Bosea also among the genera identified. Desiccation-resistant isolates accumulated high intracellular manganese and low iron concentrations compared to sensitive bacteria. In vivo , proteins of desiccation-resistant bacteria were protected from oxidative modifications that introduce carbonyl groups in sensitive bacteria during drying. We present the case that survival of bacteria that inhabit dry-climate soils are highly dependent on mechanisms, which limit protein oxidation during dehydration.

Termites produce methane (CH₄) as a by-product of microbial metabolism of food in their hindguts, and are one of the most uncertain components of the regional and global CH₄ exchange estimates. This study was conducted at Howard Springs near Darwin, and presents the first estimate of CH₄ emissions from termites based on replicated in situ seasonal flux measurements in Australian savannas. Using measured fluxes of CH₄ between termite mounds and the atmosphere, and between soil and the atmosphere across seasons we determined net CH₄ flux within a tropical savanna woodland of northern Australia. By accounting for both moundbuilding and subterranean termite colony types, and estimating the contribution from tree-dwelling colonies it was calculated that termites were a CH₄ source of +0.24 kg CH₄-C ha⁻¹ y⁻¹ and soils were a CH₄ sink of -1.14 kg CH₄-C ha⁻¹ y⁻¹. Termites offset 21% of CH₄ consumed by soil resulting in net sink strength of -0.90 kg CH₄-C ha⁻¹ y⁻¹ for these savannas. For Microcerotermes nervosus (Hill), the most abundant mound-building termite species at this site, mound basal area explained 48% of the variation in mound CH₄ flux. CH₄ emissions from termites offset 0.1% of the net biome productivity (NBP) and CH₄ consumption by soil adds 0.5% to the NBP of these tropical savannas at Howard Springs.