Changes In Carbon Content Research Articles

A multi-site approach toward assessing the effect of thinning on soil carbon contents across temperate pine, oak, and larch forests

Large divergence of the post-thinning change in soil carbon contents has impaired the evaluation of the thinning effect on forest carbon storage reported in previous case studies. In this context, the present study used a multi-site approach to assess the effect of thinning on forest floor and mineral soil carbon contents. The sites included four pine (Pinus densiflora Sieb. et Zucc.), five oak (Quercus spp.), and four larch (Larix kaempferi (Lamb.) Carr.) forests under the temperate climate, each of which included un-thinned control, intermediate thinning (15–30% basal area reduction), and heavy thinning (30–50% basal area reduction) treatments. Forest floor and mineral soil (0–10, 10–20, and 20–30 cm depths) carbon contents were determined 0–1, 3–4, and 6–7 years after thinning. The average forest floor and mineral soil (0–30 cm) carbon contents (Mg C ha−1) were 6.7 and 54.1 under the control, 6.6 and 60.7 under the intermediate thinning treatment, and 6.0 and 64.7 under the heavy thinning treatment, respectively. There was a slight decrease in forest floor carbon contents but an increase in mineral soil carbon contents under the thinning treatments, although the magnitude and direction of the thinning effect were site-specific. The magnitude of the thinning effects was stronger under the heavy thinning treatment than under the intermediate thinning treatment. However, the effect of thinning was unrelated to time after thinning and forest type. Topography (altitude and slope), soil properties (soil water content, pH, and total nitrogen concentration), diameter at breast height and height of remaining trees, and the percentage of removed basal area explained approximately 45% of variance in the thinning effect, indicating that differences in the environment are important in the divergence of the thinning effect on soil carbon contents across multiple sites. Our results suggest that designing thinning practices to foster forest carbon sequestration should consider the contribution of thinning intensity and environmental conditions to variation in the thinning effect on soil carbon contents.

Invariance of the carbonate chemistry of the South China Sea from the glacial period to the Holocene and its implications to the Pacific Ocean carbonate system

Substantial and correlated changes in marine carbonate (CaCO3) content of oceanic sediments commonly accompany the transitions from cold glacial periods to warm interglacial periods. The South China Sea (SCS) is said to be ocean-dominated at depth, and its CaCO3 records should reflect and preserve the effects of changes in the carbonate chemistry of the (western) Pacific Ocean. Using published and newly acquired CaCO3 data and a model for carbonate compensation dynamics, we show that a significant change with respect to carbonate saturation is unlikely to have occurred in the SCS during the last glacial–interglacial transition. Instead, the results from a carbonate deposition model argue that the saturation state of the SCS was largely invariant; a separate diagenetic model argues that changes in sediment CaCO3 content can be explained by alterations in lithogenic input. In turn, this could indicate that the carbonate ion concentration of the (western) Pacific at depths shallower than the sill to the SCS (ca. 2,400 m) has not changed appreciably between the last glacial period and the present interglacial.

Long-term charcoal-induced changes to soil properties in temperate regions of northern Iran

The long-term performance and benefits of charcoal application on the carbon sequestration and properties of forest soils in temperate or non-tropical regions has not been studied in detail in spite of its important role in global warming. This study was conducted to describe the long-term charcoal-induced changes in organic carbon (OC) content and other soil properties of temperate deciduous forests in Mazandaran province, northern Iran. Three sites were sampled to collect composite soil samples from two depths (0–20 and 20–40 cm) inside and outside of a plot of charcoal-enriched soils surrounding a historical charcoal production site (abandoned for more than 120 years). The presence of charcoal in soils for about 120 years elevated significantly the black carbon, total OC, natural soil OC, total nitrogen, dissolved organic matter, soil OC density, exchangeable bases, saturated hydraulic conductivity, available water capacity and available Fe, Mn and Zn compared to the adjacent reference soils. Cation exchange capacity (CEC) and pH were 15.5 cmolc kg−1 and 0.5 units, respectively, higher than the adjacent reference soils at 0–20 cm soil depth. However, electrical conductivity (EC), bulk density and available Cu were higher in the adjacent reference soil. The aged charcoal had no significant effect on the microbial respiration rate of studied soils. The results of this study provide new insights and strong support for the long-term benefits of biochar application as a management strategy for improving soil productivity as well as sequestering large quantities of durable carbon in soils of the region and mitigating global warming.

온도상승 환경 처리가 논토양과 용수에서 탄소량 변화와 벼 생육에 미치는 영향

온도상승 환경 처리가 논토양과 용수에서 탄소량 변화와 벼 생육에 미치는 영향

Soil Organic Matter Alteration Velocity due to Land-Use Change: A Case Study under Conservation Agriculture

The cultivation of native forest soils usually triggers a decline in soil organic matter (SOM) and a deterioration of aggregates. Although switching to conservation tillage (CT) can supply SOM, little is known about the temporal resolution of this change. This study aims to quantify changes in soil organic carbon (SOC) content and SOM composition of the same soil under 14 years of CT, plowing tillage (PT), and native forest (NF). Plowing ameliorates the macroaggregate-mediated loss in SOC content, in both the fine fraction and the coarse particles. Decades of CT can significantly increase both the microaggregates and fine particles related to SOC content, whereas in the finest fraction, the volume of recalcitrant SOC increased the most, and reached the original value under NF. Continuous plowing triggered SOM molecular size increases in both aggregates and the fine fraction, whereas switching to CT restored the molecular SOM size of the fine fraction only. Therefore, this fraction can be changed, even in short periods. Water dissolved the largest and middle-sized molecules of SOM, which are mainly from macroaggregates. Even if aggregation did not increase due to turning to CT, the content of the larger molecules of SOM increased in this short time.

The effect of exclosure management on the reduction of SOC loss due to splash erosion in gypsiferous soils in Southwestern Iran

An understanding of the effect of exclosure on soil organic carbon (SOC) content changes and its loss due to soil erosion in arid and semi-arid rangelands is essential to the establishment of stable ecosystem conditions. The aim of this study is to investigate the loss of SOC during natural rainfall due to splashed particles of gypsiferous soils. Accordingly, a three-factor factorial experiment is performed within a completely randomized design with a splash cup under natural rainfall over three replications. The first factor is exclosure at two levels (exclosure and non-exclosure); the second factor is rainfall erosivity factor at three levels (EI30: 1153.5, 4307.6, and 7714Jm−2cm−1); and the third factor is slope percent at three levels (0%, 5%, and 15%). The results showed that exclosure had a significant impact on soil splash erosion rate in terms of upslope splash erosion (USE), downslope splash erosion (DSE), total splash erosion (TSE), and loss of SOC. In non-exclosure conditions, the USE, DSE, and TSE increased by 32.4%, 13.5%, and 17.8%, respectively, compared to exclosure conditions. The amount of organic carbon lost due to splash in non-exclosure conditions was 1.29 times higher than in exclosure conditions. In addition, by increasing the slope and the rainfall erosivity index, a significant reduction was observed in USE and a significant increase was observed in TSE, DSE, and the loss of SOC. As a result of increasing the index EI30 from 1153.5 to 4307.6, the loss of SOC increased by a factor of 1.3, and as a result of increasing the rainfall erosivity index (EI30) from 1153.5 to 7714, the loss of SOC increased by a factor of 1.4. Organic carbon loss in the slope of 0–5% was approximately 0.061%, and by increasing the slope to 5–15%, and then 15–30%, carbon loss increased by factors of 1.5 and 1.34, respectively. Therefore, the exclosure treatment had a significant impact on reducing soil and organic carbon loss in the fields. It seems necessary, therefore, to consider exclosure treatment as a major part of renewable natural resources projects, especially in watershed management plans involving the gypsiferous soils of Iran.

A Conceptual Model for Projecting Coccolithophorid Growth, Calcification and Photosynthetic Carbon Fixation Rates in Response to Global Ocean Change

Temperature, light and carbonate chemistry speciation all influence the growth, calcification and photosynthetic carbon fixation rates of coccolithophores to a similar degree. There have been multiple attempts to project the responses of coccolithophores to changes in carbonate chemistry, but the interaction with light and temperature remains elusive. Here we devise a simple conceptual model to derive a fit equation for coccolithophorid growth, photosynthetic carbon fixation and calcification rates in response to simultaneous changes in carbonate chemistry speciation, temperature and light conditions. The fit equation is able to account for up to 88% of the variability in measured metabolic rates. Equation projections indicate that temperature, light and carbonate chemistry speciation all have different modulating effects on both optimal growth conditions and the sensitivity of responses to extreme environmental conditions. Calculations suggest that a single extreme environmental condition (CO2, temperature, light) will reduce maximum rates regardless of how optimal the other environmental conditions may be. Thus, while the response of coccolithophores to ocean change depends on multiple variables, the one which is least optimal will have the most impact on overall rates. Finally, responses to ocean change are usually reported in terms of cellular rates. However, changes in cellular rates can be a poor predictor for assessing changes in production at the community level. We therefore introduce a new metric, the calcium carbonate production potential (CCPP), which combines the independent effects of changes in growth rate and cellular calcium carbonate content to assess how environmental changes will impact coccolith production. Direct comparison of CO2 impacts on cellular CaCO3 production rates and CCPP shows that while the former is still at 45% of its pre-industrial capacity at 1000 uatm, the latter is reduced to 10%.

黔西北次生林优势树种叶片-凋落物-土壤连续体有机质碳稳定同位素特征

PDF HTML阅读 XML下载 导出引用 引用提醒 黔西北次生林优势树种叶片-凋落物-土壤连续体有机质碳稳定同位素特征 DOI: 10.5846/stxb201807091489 作者: 作者单位: 贵州师范大学喀斯特研究院/国家喀斯特石漠化防治工程技术研究中心,贵州师范大学喀斯特研究院/国家喀斯特石漠化防治工程技术研究中心,贵州师范大学地理与环境科学学院,贵州师范大学地理与环境科学学院 作者简介: 通讯作者: 中图分类号: 基金项目: 国家重点研发计划项目课题（2016YFC0502601）；贵州省科技计划项目（黔科合LH字[2016]7201号） Carbon stable isotopic characteristics of organic matter in the leaf-litter-soil continuum of dominant tree species in a secondary forest in northwestern Guizhou Author: Affiliation: School of Karst Science,Guizhou Normal University,,, Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:稳定性碳同位素自然丰度（δ13C）能够揭示生态系统长时间尺度的有机碳动态变化，阐明生态系统功能的变化特征。以黔西北次生林14个优势树种为研究对象，测定叶片、凋落物以及根区土壤有机碳含量和δ13C值，分析不同层次碳含量和δ13C丰度之间的相关性。结果表明：14个优势树种叶片碳含量为404.67-487.14 g/kg，总体为针叶树种较高、常绿灌木较低；δ13C值为-31.2‰—-27.1‰，随生活型的变化规律不明显。凋落物碳含量为414.62-561.31 g/kg，与叶片碳含量的变化规律较为一致；δ13C值为-31.5‰—-27.3‰，随树种生活型的变化特征也不明显。根区土壤碳含量为10.02-91.59 g/kg，δ13C值为-26.8‰—-22.5‰，碳含量以光皮桦、银白杨等落叶乔木较高。叶片、凋落物和根区土壤3个层次的碳含量与δ13C丰度之间均呈不显著相关，不同层次的δ13C丰度之间和碳含量之间均为正相关。研究结果有助于反映森林生态系统碳循环过程的关键信息，为森林植被恢复提供理论依据。 Abstract:The natural abundance of stable carbon isotopes (δ13C) can reveal the dynamic changes of organic carbon over time and illustrate the characteristics of functional changes in ecosystems. Using 14 dominant tree species in the secondary forest in northwestern Guizhou, the organic carbon contents and δ13C values in leaves, litter, and root-zone soil were measured to analyze the correlation between carbon content and δ13C abundance at different levels. The results showed that:the carbon content of leaves of the 14 dominant tree species was 404.67-487.14 g/kg. Generally, the carbon content was higher in conifers and lower in evergreen shrubs. The δ13C value was -31.2‰ to -27.1‰, and the change with life form was not obvious. The litter carbon content was 414.62-561.31 g/kg, which was consistent with the change of leaf carbon content; the δ13C value was -31.5‰ to -27.3‰, and the changing characteristics of life form in tree species were not obvious. The carbon content in root-zone soil was 10.02-91.59 g/kg, the δ13C value was from -26.8‰ to -22.5‰. The carbon content was higher in deciduous trees, such as Rhododendron simsii and Populus alba. There was no significant correlation between the carbon content of leaves, litter, and root-zone soil at different levels and the abundance of δ13C value. A positive correlation was found between the abundance of δ13C value and carbon content at different levels. The results could help to reveal fundamental information of the carbon cycle process in forest ecosystems and provide a theoretical basis for forest vegetation restoration. 参考文献 相似文献 引证文献

Investigating the Changes of Total Organic Carbon Content in Bottled Water Under Environmental Stress Conditions

The consumption of bottled drinking water has increased considerably in the recent years. The main objective of this study was to investigate the changes of total organic carbon (TOC) level in bottled water under various environmental stress conditions. In this study, samples of drinking water were taken just before and after bottling process from three mineral water bottling plants in Tehran province, and the comparison of the levels of TOC content of the water was evaluated before and after bottling process, and at the end of the consumption period. The results indicate that TOC level in mineral water increases over time. There were very few changes of TOC level in the bottled water after one day. After one month and then three months, the changes became more significant in a way that the TOC level increased from 1.6 to 2.33 mg/L. Studying the bottled waters just few days left to their expiration dates revealed that the level of TOC increased twice, i.e. from 1.6 to 2.9 mg/L. Also, the level of TOC in samples changed significantly one month after the expiration date, and it increased from the initial 1.6 to 3.2mg/L. The level of TOC in samples exposed to sun was almost four times more, and reached its highest level of 5.47 mg/L. Also, the level of changes in samples after freezing increased from initial 1.6 to 4.11 mg/L.

Assessment of hydrocarbon degradation potentials in a plant–microbe interaction system with oil sludge contamination: A sustainable solution

ABSTRACTA pot culture experiment was conducted for 90 days for the evaluation of oil and total petroleum hydrocarbon (TPH) degradation in vegetated and non-vegetated treatments of real-field oil-sludge-contaminated soil. Five different treatments include (T1) control, 2% oil-sludge-contaminated soil; (T2), augmentation of microbial consortium; (T3), Vertiveria zizanioides; (T4), bio-augmentation along with V. zizanioides; and (T5), bio-augmentation with V. zizanioides and bulking agent. During the study, oil reduction, TPH, and degradation of its fractions were determined. Physico-chemical and microbiological parameters of soil were also monitored simultaneously. At the end of the experimental period, oil content (85%) was reduced maximally in bio-augmented rhizospheric treatments (T4 and T5) as compared to control (27%). TPH reduction was observed to be 88 and 89% in bio-augmented rhizospheric soil (T4 and T5 treatments), whereas in non-rhizospheric and control (T2 and T1), TPH reduction was 78 and 37%, respectively. Degradation of aromatic fraction after 90 days in bio-augmented rhizosphere of treatments T4 and T5 was found to 91 and 92%, respectively. In microbial (T2) and Vertiveria treatments (T3), degradation of aromatic fraction was 83 and 68%, respectively. A threefold increase in soil dehydrogenase activity and noticeable changes in organic carbon content and water-holding capacity were also observed which indicated maximum degradation of oil and its fractions in combined treatment of plants and microbes. It is concluded that the plant–microbe soil system helps to restore soil quality and can be used as an effective tool for the remediation of oil-sludge-contaminated sites.

Electrochemical analysis of slurry electrodes for flow-electrode capacitive deionization

Due to recent advancements in electrochemical devices such as batteries, fuel cells, and supercapacitors, novel electrochemical processes for industrial plant scale including water treatment and desalination are being actively investigated. Slurry electrodes for flow-electrode capacitive deionization (FCDI) are representative process technology with continuous and easy scale-up characteristics. These characteristics are feasible as slurry electrodes can be flowed in microchannels, instead of stacking conventional electrodes fixed on plates. However, the electrochemical properties of slurry electrodes for electrochemical process engineering have not been clearly identified, compared to those of conventional fixed electrodes. In the present study, we investigated the electrochemical properties of capacitive slurry electrodes with changes in carbon content and electrolyte salt concentration using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and deionization/regeneration cycle tests with newly fabricated button-type cells. The CV patterns were rectangular, symmetrical, and reversible at a scan rate of 2mV/s, indicating electrical double-layer capacitive behavior. The results of the EIS and cycle tests demonstrated that increasing the carbon content and electrolyte salt concentration in slurry electrodes improved the cell efficiency due to the higher capacitance and lower total resistance.

Aggregation and fractal dimension of aggregates formed in sand dunes stabilized byPistachioPAMandPistachioPVAc mulches

Wind erosion is a serious environmental problem that has received increased attention by attracting the interest of academics, policy makers and the public. In this study, the effects of combined mulches (denoted asPistachioPAMandPistachioPVAc, used for stabilizing the sand dunes in theDavaran plain in southeasternIran) on aggregate formation and stability indices were investigated by the theory of fractal geometry. In addition, the temporal changes in soil organic carbon (SOC) content and microbial respiration rate (MRR) in the soils treated with the mulches were compared with the control samples during a 5‐month experiment. The results showed significant (P < 0.01) increases in theSOCcontent andMRRfollowing the application (1.5 l m−2) ofPistachioPVAcandPistachioPAMmulches. The rate of release ofCO2was measured in the soils treated with the mulches studied. The largest rate ofCO2release from the three samples taken in weeks 2, 5 and 19 from the beginning of the experiment was about 23.0 µg‐CO2day−1 g−1soil. The smallest and largest mean weight diameters (MWD) of the aggregates formed were observed in the control (0.06 mm) and thePistachioPVAc(1.38 mm) treatments, respectively. The use of mulches had significant (P < 0.01) effects on the fractal dimension of aggregates. The more stable and coarser aggregates formed in the presence ofPistachioPVAchad the smallest fractal dimension. The largest negative correlation between the properties investigated and the fractal dimension was forSOCandMWD. Therefore, it appears that the theory of fractal dimensions is useful for explaining the temporal variation of aggregate stability in soil stabilized by combined mulches.HighlightsEffects of combined mulches on aggregate formation were investigated with fractal geometry theory (FGT).The more stable and coarser aggregates formed in the presence ofPistachioPVAmulch had the smallest fractal dimension.Mulches increased soil organic carbon and microbial respiration significantly (P < 0.01).TheFGTmight be useful for explaining the temporal variation in aggregate stability of stabilized sand dunes.

Influence of carbonaceous materials on the interactions among (Al2O3-C)/Fe system with temperature and soaking time

It has practical significance for improving the service life of Al2O3-C refractories and reducing its influence on steel quality to reveal the reaction mechanism among (Al2O3-C)/Fe system under high temperature. The influence of carbonaceous materials on the interactions among (Al2O3-C)/Fe system with temperature and soaking time were studied using thermalgravity method in this paper in order to get a better understanding on the reaction mechanism among (Al2O3-C)/Fe system. The weight loss of (Al2O3-C)/Fe samples and the formation of Al2O3 crystal whiskers along with the change of aluminium and carbon content in iron indicates the mechanism of the effects of carbonaceous materials on the reactions among (Al2O3-C)/Fe system under high temperature. The result showed that the aluminium pickup of iron was not only due to the dissolution of Al2O3 in molten iron but mostly due to the carbothermic reduction of Al2O3 and carbonaceous materials in the presence of molten iron.

Surface integrity analysis of 20CrMnTi steel gears machined using the WD-201 microcrystal corundum grinding wheel

The purpose of the research is to study the grinding properties and mechanisms of 20CrMnTi steel gears machined by WD-201 microcrystal corundum grinding wheels. It conducted experimental study analysis on the integrity of grinding surfaces. Firstly, it analysed the trends in gradient change of carbon concentration in carburized layers of gear blanks on microhardness, retained austenite, and lath martensite. Secondly, it discussed the effect, and mechanisms, of transformation morphologies of different metallographic structures on residual stresses and their microhardness. In addition, the effects of grinding speed, radial feed, and axial feed rate on grinding temperature, microhardness, and depth of metamorphic layers were analysed. These provide experimental bases for the reasonable selection of gear grinding processes.

Estimating Mangrove Canopy Height and Above-Ground Biomass in the Everglades National Park with Airborne LiDAR and TanDEM-X Data

Mangrove forests are important natural ecosystems due to their ability to capture and store large amounts of carbon. Forest structural parameters, such as canopy height and above-ground biomass (AGB), provide a good measure for monitoring temporal changes in carbon content. The protected coastal mangrove forest of the Everglades National Park (ENP) provides an ideal location for studying these processes, as harmful human activities are minimal. We estimated mangrove canopy height and AGB in the ENP using Airborne LiDAR/Laser (ALS) and TanDEM-X (TDX) datasets acquired between 2011 and 2013. Analysis of both datasets revealed that mangrove canopy height can reach up to ~25 m and AGB can reach up to ~250 Mg•ha−1. In general, mangroves ranging from 9 m to 12 m in stature dominate the forest canopy. The comparison of ALS and TDX canopy height observations yielded an R2 = 0.85 and Root Mean Square Error (RMSE) = 1.96 m. Compared to a previous study based on data acquired during 2000–2004, our analysis shows an increase in mangrove stature and AGB, suggesting that ENP mangrove forests are continuing to accumulate biomass. Our results suggest that ENP mangrove forests have managed to recover from natural disturbances, such as Hurricane Wilma.

Selenium deficiency risk predicted to increase under future climate change

Deficiencies of micronutrients, including essential trace elements, affect up to 3 billion people worldwide. The dietary availability of trace elements is determined largely by their soil concentrations. Until now, the mechanisms governing soil concentrations have been evaluated in small-scale studies, which identify soil physicochemical properties as governing variables. However, global concentrations of trace elements and the factors controlling their distributions are virtually unknown. We used 33,241 soil data points to model recent (1980-1999) global distributions of Selenium (Se), an essential trace element that is required for humans. Worldwide, up to one in seven people have been estimated to have low dietary Se intake. Contrary to small-scale studies, soil Se concentrations were dominated by climate-soil interactions. Using moderate climate-change scenarios for 2080-2099, we predicted that changes in climate and soil organic carbon content will lead to overall decreased soil Se concentrations, particularly in agricultural areas; these decreases could increase the prevalence of Se deficiency. The importance of climate-soil interactions to Se distributions suggests that other trace elements with similar retention mechanisms will be similarly affected by climate change.

Changes in organic carbon content and its physical and chemical distribution in paddy soils cultivated under different fertilisation practices

Purpose Chemical protection facilitates soil organic carbon (SOC) sequestration and stabilisation due to a strong chemical binding with mineral surfaces and metal ions (e.g. iron [Fe], aluminium [Al] and calcium [Ca]). However, there is not much information regarding the role of chemical protection in SOC stabilisation in paddy soils, particularly in terms of the specific forms of organo-mineral complexes such as Fe-, Al- and Ca-bonded OC.

Preliminary investigation of electrical conductivity of monolithic biochar

Monolithic biochar is explored as electrode material in supercapacitor – a fast-charging, long-lasting energy storage device. Electrical conductivity of electrode is critical to supercapacitor's performance. Traditionally, biochar is used as a solid fuel for combustion where electrical conductivity is largely irrelevant and ignored. This work explores electrical conductivity of monolithic biochar and elucidates its dependence on micro and macro structures of biochar. Electrical conductivity of biochar was found to be highly dependent on its degree of carbonization. Bulk conductivity of biochar can increase by over six orders of magnitudes when its carbon content changes from 86.8 to 93.7 wt%. Transmission electronic microscope and x-ray diffraction analyses revealed the presence of graphite nanocrystals (∼3 nm) and the growth of biochar crystallinity after heat treatment at 950 °C. The highest skeletal conductivity of carbon was 343.2 S/m, found in a heat-treated sugar maple biochar with 96.2 wt% of carbon. It is higher than that of graphite single crystal in direction perpendicular to graphene plane (333.3 S/m). Moreover, it was observed conductivity of monolithic biochar increased with compressive loading and dropped to the pre-compression level when the loading was released - a new phenomenon termed “elastic behavior of electrical conductivity of biochar”.

David Stewart Jenkinson. 25 February 1928 — 16 February 2011

David Jenkinson was one of the most influential soil scientists of his generation, bringing new insights into the transformations of organic matter and nitrogen in soil. He spent the majority of his career at Rothamsted Research, Harpenden, UK. His studies were influential regarding the role of soil carbon stocks in the context of climate change and the role of nitrogen fertilizer in delivering adequate supplies of food for a growing world population. His research encompassed both fundamental studies on soil processes and immensely practical applications of this knowledge, often utilizing the Rothamsted long-term experiments that have run for over 170 years. He is particularly well known for his development of a method for determining the quantity of organic carbon held in the cells of living micro-organisms in soil, termed the ‘soil microbial biomass’. This breakthrough opened the way for a new wave of soil biological research. David developed one of the earliest computer models for the turnover of organic carbon in soil, known as the Rothamsted Carbon Model, RothC. This model, conceptually very simple, has proved highly successful in simulating and predicting changes in soil organic carbon (SOC) content under different management practices worldwide, being used by over 2600 people in 115 countries. His research using the stable isotope of nitrogen, 15 N, in large-scale field experiments drew attention to the factors leading to inefficiencies in the use of nitrogen fertilizer but also demonstrated that it is possible to achieve high efficiency if good agricultural management practices are followed. It also demonstrated, more clearly than previously, the great importance of soil organic matter as a source of nitrogen for crops and the role of the soil microbial biomass both in immobilizing a proportion of applied fertilizer nitrogen and also in causing confusion in the interpretation of such experiments. By calculating nitrogen budgets for the Rothamsted long-term experiments he quantified the deposition of nitrogen compounds from atmosphere to land, laying foundations for later studies concerning the ecological and agricultural impacts of this significant input of nitrogen.

Changes in soil carbon, nitrogen and sulphur content as influenced by liming and nitrogen fertilization of three energy crops

The paper presents research findings, obtained through a long-term research programme “Productivity and sustainability of agricultural and forest soils” implemented by the Lithuanian Research Centre for Agriculture and Forestry.