Carbon Increment Research Articles

Effect of Rapid Heat Treatment on Bake Hardening Behavior of a Low Carbon Steel

A low carbon steel was firstly annealed with an ultra- rapid heating rate of 200℃/s at 660℃ and 750℃ respectively, then the steel was pre-strained to 2% and finally suffered a baking hardening treatment at 180℃ for 20 min in order to reveal the synergistic effect of the above two heat treatments of the performance of the low carbon steel in terms of heating temperature, soaking time and cooling rate etc. Results indicated that the bake hardening was enhanced with the increase in annealing temperature for the dissolution of the carbides. The BH value of the low carbon steel annealed at 660℃ decreased significantly with increasing soaking time. But the BH value showed a complex variation with soaking time for the steel annealed at 750℃ because the carbides dissolved incompletely during the ultra-rapid heating process: with an increase in soaking time in the range of 0 to 10 s, the BH value made an apparent increment, and then decreased obviously when the soaking time exceeded 10 s. The bake hardening of the steel is enhanced significantly with increasing cooling rate due to the increment of the solute carbon.

Influence of stocking, site quality, stand age, low-severity canopy disturbance, and forest composition on sub-boreal aspen mixedwood carbon stocks

Low-severity canopy disturbance presumably influences forest carbon dynamics during the course of stand development, yet the topic has received relatively little attention. This is surprising because of the frequent occurrence of such events and the potential for both the severity and frequency of disturbances to increase as a result of climate change. We investigated the impacts of low-severity canopy disturbance and average insect defoliation on forest carbon stocks and rates of carbon sequestration in mature aspen mixedwood forests of varying stand age (ranging from 61 to 85 years), overstory composition, stocking level, and site quality. Stocking level and site quality positively affected the average annual aboveground tree carbon increment (CAAI), while stocking level, site quality, and stand age positively affected tree carbon stocks (CTREE) and total ecosystem carbon stocks (CTOTAL). Cumulative canopy disturbance (DIST) was reconstructed using dendroecological methods over a 29-year period. DIST was negatively and significantly related to soil carbon (CSOIL), and it was negatively, albeit marginally, related to CTOTAL. Minima in the annual aboveground carbon increment of trees (CAI) occurred at sites during defoliation of aspen (Populus tremuloides Michx.) by forest tent caterpillar (Malacosoma disstria Hubner), and minima were more extreme at sites dominated by trembling aspen than sites mixed with conifers. At sites defoliated by forest tent caterpillar in the early 2000s, increased sequestration by the softwood component (Abies balsamea (L.) Mill. and Picea glauca (Moench) Voss) compensated for overall decreases in CAI by 17% on average. These results underscore the importance of accounting for low-severity canopy disturbance events when developing regional forest carbon models and argue for the restoration and maintenance of historically important conifer species within aspen mixedwoods to enhance stand-level resilience to disturbance agents and maintain site-level carbon stocks.

Greenhouse gas emissions and carbon stock changes in rubber tree plantations in Thailand from 1990 to 2004

Abstract Rubber trees provide a variety of raw materials to manufacturing industries. Evaluating the environmental impacts throughout the life cycle of the trees is therefore important. In this study, the carbon stock and greenhouse gas emission profile throughout the complete cropping cycle of rubber plantations was estimated. The amount of biomass carbon stocks per hectare were estimated using a logistic growth model, expressed as 142.47/(1 + 13.31e −0.19 t ), where t is rubber age. Using this model, we found that carbon stocks in rubber tree plantations were continuously increasing until the rubber trees reached an age of 22–25 years. On average, the carbon stock in the 25 years of a rubber tree biomass was about 128.4 t C ha −1 . Although the carbon stock in latex also increased in a similar way to that of rubber trees, it was much less than that in the biomass of the rubber trees. Based on calculations involving Thailand's total rubber planting area (with various ages of rubber trees), the yearly average carbon stock change was the net increase of 1.71 Mt C y −1 . On the other hand the yearly average greenhouse gas emission from cultivation of rubber tree was 0.32 Mt C-e y −1 . Compared to the increment of biomass carbon, the carbon emissions from rubber cultivation activities, mainly from fertilizer and herbicide application, were relatively small.

A comparative study of ultrasonication, Fenton's oxidation and ferro-sonication treatment for degradation of carbamazepine from wastewater and toxicity test by Yeast Estrogen Screen (YES) assay

A comparative study of ultrasonication (US), Fenton's oxidation (FO) and ferro-sonication (FS) (combination of ultrasonication and Fenton's oxidation) advanced oxidation processes (AOPs) for degradation of carbamazepine (CBZ) from wastewater (WW) is reported for the first time. CBZ is a worldwide used antiepileptic drug, found as a persistent emerging contaminant in many wastewater treatment plants (WWTPs) effluents and other aquatic environments. The oxidation treatments of WW caused an effective removal of the drug. Among the various US, FO and FS pre-treatments carried out, higher soluble chemical oxygen demand (SCOD) and soluble organic carbon (SOC) increment (63 to 86% and 21 to 34%, respectively) was observed during FO pre-treatment process, resulting in higher removal of CBZ (84 to 100%) from WW. Furthermore, analysis of by-products formed during US, FO and FS pre-treatment in WW was carried out by using laser diode thermal desorption-atmospheric pressure chemical ionization (LDTD-APCI) coupled to tandem mass spectrometry (MS/MS). LDTD-APCI–MS/MS analysis indicated formation of two by-products, such as epoxycarbamazepine and hydroxycarbamazepine due to the reaction of hydroxyl radicals (OH) with CBZ during the three types of pre-treatment processes. In addition, the estrogenic activity of US, FO and FS pre-treated sample with CBZ and its by-products was carried out by Yeast Estrogen Screen (YES) assay method. Based upon the YES test results, none of the pre-treated samples showed estrogenic activity.

Substantial amounts of carbon are sequestered during dry periods in an old-growth subtropical forest in South China

A number of continuous eddy covariance measurements and long-term biomass inventories had proved that old-growth forests are carbon sinks worldwide. The present study estimated the net ecosystem productivity (NEP) for an old-growth subtropical forest at the Dinghushan Biosphere Reserve in South China to investigate the temporal pattern of carbon sequestration, both seasonally and annually. The measured NEP over 7 years (from 2003 to 2009) showed that this forest was a net carbon sink, ranging from 230 (in 2008) to 489…−2 year−1 (in 2004). The greatest value of NEP was found in the driest year and the lowest value in the wettest year during the study period. Within a year, NEP during the dry season was about 81.4 % higher than for the wet season. Accordingly, the dry season at seasonal scale and dry years at interannual scale are key periods for carbon sequestration in this forest. The strong seasonality of ecosystem or soil respiration (ER or SR) compared with gross primary productivity (GPP) resulted in substantial amounts of carbon being sequestered during dry seasons. A decrease of GPP and an increase of ER or SR demonstrated the lower carbon uptake in rainy years. From this study, we conclude that GPP and living biomass carbon increment are not overriding parameters controlling NEP. The variations in ER or SR driven by the rainfall scheme were the dominant factor determining the magnitude of NEP in this forest in South China.

Partial ozonation pre-treatment for sludge solubilization and simultaneous degradation of bisphenol A: quantification studies

Ozonation pre-treatment was investigated for the enhancement of sludge solids and organic matter solubilization and simultaneous degradation of bisphenol A (BPA), an endocrine disruptor compound from wastewater sludge (WWS). The ultrafast method (15 s per sample) used for the analysis of BPA in WWS is based on Laser Diode Thermal Desorption/Atmospheric Pressure Chemical Ionization coupled to tandem Mass Spectrometry. The statistical methods used for optimization studies comprised the response surface method with fractional factorial designs and central composite designs. The ozonation pre-treatment process was carried out with four independent variables, namely WWS solids concentration (15–35 g l −1), pH (5–7), ozone dose (5–25 mg g −1 SS) and ozonation time (10–30 min). It was observed that among all the variables studied, ozone dose had more significantly (probability (p)<0.001) affected the efficiency of the ozonation pre-treatment by increasing sludge solids (suspended solids (SS) and volatile solids) solubilization and organic matter (soluble chemical oxygen demand and soluble organic carbon) increment and BPA degradation from WWS. During the optimization process, it was found that higher BPA degradation (100%) could be obtained with 24 g l −1 SS, 6.23 pH with an ozone dose of 26.14 mg g −1 SS for 16.47 min ozonation time. The higher ozone dose used in this study was observed to be cost effective on the basis of solids and organic matter solubilization and degradation of BPA.

Assessment of Carbon Balance in Community Forests in Dolakha, Nepal

This study assessed the net above-ground carbon stock in six community forests in the Dolakha district, Nepal. A survey was conducted of above-ground timber species, using random sampling. A tree-ring chronology for Pinus roxburghii was created to construct a growth model representative of the various mainly-pine species. The allometric model combined with tree ring analysis was used to estimate carbon stock and annual growth in the above-ground tree biomass. The out-take of forest biomass for construction material and fuelwood was estimated on the basis of interviews and official records of community forest user groups. The average annual carbon increment of the community forests was 2.19 ton/ha, and the average annual carbon out-take of timber and fuelwood was 0.25 ton/ha. The net average carbon balance of 1.94 ton/ha was equivalent to 117.44 tons of carbon per community forest annually. All the community forests were actively managed leading to a sustainable forest institution, which acts as a carbon sink. It is concluded that community forests have the potential to reduce emissions by avoiding deforestation and forest degradation, enhance forest carbon sink and improve livelihoods for local communities.

Storm pulses and varying sources of hydrologic carbon export from a mountainous watershed

Summary Although soil erosion and leaching can transfer a substantial portion of the annual terrestrial carbon (C) increment to aquatic systems, little is known about rapid changes in the amount and characteristics of soil organic C exported from mountainous watersheds during storm events. To trace short-term changes in sources and characteristics of soil organic C exported during storm events, we investigated storm-induced changes in concentrations of particulate and dissolved organic C (POC and DOC) and the stable isotope composition of suspended sediment (SS) in a mountainous, mixed land-use watershed in northern South Korea. Biweekly stream sampling in a headwater forest stream and a watershed outlet receiving agricultural runoff showed that concentrations of SS and POC were higher in the watershed outlet. In both the forest stream and outlet, POC concentrations were lower than DOC concentrations during baseflow, but increased rapidly with rising discharge during intense storms, resulting in higher peak POC concentrations than peak DOC concentrations. When δ13C and δ15N were compared between SS and potential source soils during three storm events, SS δ13C and δ15N in the forest stream were similar to forest floor δ13C and δ15N. SS δ13C and δ15N in the watershed outlet reflected the contribution from forest and cropland mineral soils during peak flow, with sand-size SS displaying increasing δ13C and δ15N with rising rainfall intensity. The results suggest that storm pulses of POC can be a transient, but dominant pathway of hydrologic C export overwhelming DOC export and that POC sources and characteristics can rapidly change corresponding to varying rainfall intensity.

Estimates of Biomass and Fixed Carbon at a Rainforest in Panama

This paper presents an estimation of the quantity of carbon fixed in trees in a one hectare (ha) plot at the Cerro Pelado-Gamboa Hydrology Tropical Observatory, which is located in the province of Colon, Panama. The estimation of carbon fixed in trees may provide significant information on carbon flux due to water circulation, which may ultimately enable evaluation of the carbon cycle. All trees larger than 10 cm diameter at breast height (DBH) in the plot were investigated. Carbon fixed within these trees was estimated using a parameterized formula. Tree biomass estimations for the plot were 97.21 Mg ha-1. We identified a rare arboreal pear species ( Euphorbiaceous) with higher carbon density than other trees in the plot. The presence of this apparently unique species may be due to specific soil characteristics. The method was evaluated by comparing the results with a second study performed in 2011, which resulted in an estimate of net new carbon (biomass) increment (NNCI), which gives 3.88 Mg ha-1 year-1. In general, the estimation of the biomass and associated carbon content found in this investigation are useful comparative data for economic evaluation of tropical forests in terms of capacity to capture carbon.

Carbon density in managed coast redwood stands: implications for forest carbon estimation

Summary Carbon sequestration and wood volume production will be major objectives of future forestry projects. Optimization of these two objectives will require a better understanding of how management regimes affect stand average wood density and carbon fraction. Two contrasting coast redwood (Sequoia sempervirens) sites were chosen for analysis of volume growth rates and tree stem carbon sequestration rates under two management systems—even-aged and multiaged—each with various treatments. A young plantation showed high volume increment and stem carbon sequestration rates in all treatments with the highest in the control plots. Control plots in the plantation had peak periodic volume increment of 75.6 m 3 ha 21 year 21 and a maximum stem carbon sequestration rate of 16.08 tonnes C ha 21 year 21 . The multiaged stand in contrast had the lowest volume and carbon increment in the control plots at 11.97 m 3 ha 21 year 21 and 2.40 tonnes C ha 21 year 21 , respectively. In both the management systems, significant differences were observed in the carbon fraction (mass carbon per unit mass dry wood) of heartwood (HW) and sapwood (SW) at 0.5385 and 0.5293, respectively, implying that increasing the ratio of HW to SW will result in higher average carbon fractions. Carbon density varied between management regimes with the highest values occurring in the multiaged stand indicating the potential for enhancement of carbon sequestration through silvicultural prescriptions. Utilization of standard carbon accounting practices resulted in a systematic underestimate of stand-level carbon stocks for both systems studied of 26 per cent in the even-aged stand and 27 per cent in the multiaged stand.

Regional Impacts of a Program for Private Forest Carbon Offset Sales

Abstract Policymakers are examining a wide range of alternatives for climate change mitigation, including carbon offset sales programs, to enhance sequestration in the forest sector. Under an offset sales program, on-the-ground forestry could change as a result of both afforestation and modifications in the management of existing forests. These effects could vary markedly by region in the United States because of differences in areas of agricultural land suitable for afforestation, forest carbon and volume growth characteristics, the structure of landownership, and forest industry concentration. Using a dynamic model of North American markets, our analysis of alternative carbon price levels suggests that the largest carbon increment response would come from changes in forest management: extending rotations, shifting silvicultural regimes, and reforestation to hardwood forest types (in some regions). Carbon payments could also stimulate a substantial afforestation response in eastern regions (North and South). Afforestation is particularly important in the North where timberland area could expand markedly. Much of the area would be planted to hardwoods, stemming the projected decline in hardwood forest types and growing stock volume.

Biomass and carbon stock in Jatropha curcas L

This study aims to quantify the biomass and carbon stock in a crop of physic nut Jatropha curcas in Viçosa-MG at age three years. For biomass quantification, the direct or destructive method was applied to sample plants selected according to height, crown diameter and number of branches. For the determination of dry biomass in the field, the proportionality method was used. The determination of total carbon content was done in the Laboratory of Forest Soils of the Federal University of Viçosa, and the estimation of CO2 equivalent was based on the 3.67 factor. The carbon stock found in the third year of cultivation was 4.182 tC.ha-1 (15.349 tCO2-e.ha-1) and the mean annual increment (MAI) was 1.394 tC.ha-1.year-1. Results revealed that the potential carbon increment in the physic nut crop is similar to values found in other crops and natural forests yet lower than in eucalyptus crops.

Leaf Area Index, Biomass Carbon and Growth Rate of Radiata Pine Genetic Types and Relationships with LiDAR

Relationships between discrete-return light detection and ranging (LiDAR) data and radiata pine leaf area index (LAI), stem volume, above ground carbon, and carbon sequestration were developed using 10 plots with directly measured biomass and leaf area data, and 36 plots with modelled carbon data. The plots included a range of genetic types established on north- and south-facing aspects. Modelled carbon was highly correlated with directly measured crown, stem, and above ground biomass data, with r = 0.92, 0.97 and 0.98, respectively. LiDAR canopy percentile height (P30) and cover, based on all returns above 0.5 m, explained 81, 88, and 93% of the variation in directly measured crown, stem, and above ground live carbon and 75, 89 and 88% of the modelled carbon, respectively. LAI (all surfaces) ranged between 8.8–19.1 in the 10 plots measured at age 9 years. The difference in canopy percentile heights (P95–P30) and cover based on first returns explained 80% of the variation in total LAI. Periodic mean annual increments in stem volume, above ground live carbon, and total carbon between ages 9 and 13 years were significantly related to (P95–P30), with regression models explaining 56, 58, and 55%, respectively, of the variation in growth rate per plot. When plot aspect and genetic type were included with (P95–P30), the R2 of the regression models for stem volume, above ground live carbon, and total carbon increment increased to 90, 88, and 88%, respectively, which indicates that LiDAR regression equations for estimating stock changes can be substantially improved by incorporating supplementary site and crop data.

Study on Effects of Organic Carbon Emission of Land Use Change in Shenzhen City, China

The effects of terrestrial carbon cycle caused by Land use change on are obvious. Urbanization is an important reason of land use change. Based on the soil and plant data that field sampled, five remote sensing data of 1979, 1989, 1995, 2000 and 2003, the effects on ecosystem organic carbon pool from1979 to 2003 caused by land use change in Shenzhen city are analyzed. The land use changes are mainly occurred between the following 8 land types, farmland, wood land, grass land and construction land. The results show that form 1979 to 2003 carbon emissions caused by land use change in Shenzhen City totally reduced by 337.24 × 104Mg C (1Mg C = 1 × 106g C). The average annual carbon emissions arrive up to 24.09 × 104Mg C. Among them, the emissions caused by the reductions of farmland and forest area are respectively 252.26 × 104Mg C and 111.73 × 104Mg C. The organic carbon increment caused by garden land increase is 47.37 × 104Mg C. The results show that Urbanization process totally is a carbon sink process. The study is valuable for assessing the relations between carbon effects and land development and ecological restoration planning in the process of rapid urbanization.

Forest management for mitigation and adaptation to climate change: Insights from long-term silviculture experiments

Developing management strategies for addressing global climate change has become an increasingly important issue influencing forest management around the globe. Currently, management approaches are being proposed that intend to (1) mitigate climate change by enhancing forest carbon stores and (2) foster adaptation by maintaining compositionally and structurally complex forests. However, little is known about the compatibility of these two objectives or the long-term efficacy of a given management regime at simultaneously achieving adaptation and mitigation. To address this need, we examined stand-level carbon and complexity responses using five long-term (>50 yrs) silviculture experiments within the upper Great Lakes region, USA. In particular, live tree carbon stores and sequestration rates, and compositional and structural complexity were analyzed from three thinning experiments in Pinus resinosa and two selection method experiments in northern hardwood systems to elucidate the long-term effects of management on these ecosystem attributes and the general compatibility of mitigation and adaptation objectives. As expected, we observed a general increase in large tree densities with stand age and positive relationships between stand stocking level and live tree carbon stores. More importantly, our results clearly identify tradeoffs between the achievement of mitigation and adaptation objectives across each study. For example, maintaining higher stocking levels (i.e., enhanced mitigation by increasing carbon stores) resulted in decreases in stand-level structural and compositional complexity (i.e., reduced adaptation potential). In addition, rates of live tree carbon increment were also the lowest within the highest stocking levels; despite the benefits of these stand conditions to maximizing carbon stores. Collectively, these findings underscore the importance of avoiding rigid adherence to a single objective, such as maximum on-site carbon stores, without recognizing potential consequences to other ecosystem components crucial to ensuring long-term ecosystem functioning within the context of environmental change. One potential stand-level strategy for balancing these goals may be to employ multi-aged management systems, such as irregular shelterwood and selection systems, that maintain a large proportion of carbon stores in retained mature trees while using thinning to create spatial heterogeneity that promotes higher sequestration rates in smaller, younger trees and simultaneously enhances structural and compositional complexity.

Is the net new carbon increment of coppice forest stands of Quercus ilex ssp. ballota affected by post-fire thinning treatments and recurrent fires?

Coppice forest stands of Quercus ilex have been one of the forest types most impacted by fire in Spain. After fire, their capability to resprout produces a high density of stems that requires thinning in order to avoid stagnation within the stands. In August 1993 and July 2001, two consecutive fires affected a Quercus ilex coppice stand in SE Spain. This study investigated the effects of different post‐fire thinning treatments and recurrent fires on stock and net new carbon increment (NNCI) in a 6‐year‐old coppice stand. Four degrees of thinning were applied: medium thinning (to a final density of 5000 trees ha–1), drastic thinning (to 1800 trees ha–1), full felling (all trees removed) and no thinning (control). Results showed NNCI was within the lower limit of the average global values reported for net primary productivity of terrestrial ecosystems. The best thinning treatment to maximise both current annual NNCI and mean annual NNCI stimulation, and keep new resprouting within reasonable levels was medium thinning. However, recurrent fires caused the observed net primary productivity to decrease, which allowed us to conclude that stump vitality is affected by successive fires, at least the first year after a new fire.

Solidification structures on carbon materials surface-melted by repetitive laser pulses

The solidification morphology of carbon materials surface-melted by laser radiation at atmospheric pressure is studied. Electron microscopy results indicate that melt solidification is accompanied by the formation of surface microstructures, presumably due to the Rayleigh—Taylor instability in the molten carbon. The instability increment and surface tension coefficient of molten carbon are estimated, and the penetration of carbon vapour into the melt during one laser pulse is examined using numerical simulation.

Soil carbon dynamics following afforestation of a tropical savannah with Eucalyptus in Congo

Soil organic matter is a key factor in the global carbon cycle, but the magnitude and the direction of the change in soil carbon after afforestation with Eucalyptus in the tropics is still a matter of controversy. The objective of this work was to understand the dynamics of soil carbon in intensively managed Eucalyptus plantations after the afforestation of a native savannah. The isotopic composition (δ) of soil carbon (C) and soil CO2 efflux (F) were measured on a four-age chronosequence of Eucalyptus and on an adjacent savannah. δF was used to partition F between a C3 component and a C4 component, the latter corresponding to the decomposition of a labile pool of savannah-derived soil carbon (CSL). The mean residence time of CSL was 4.6 years. This further allowed us to partition the savannah-derived soil carbon into a labile and a stable (CSS) carbon pool. CSL accounted for 30% of soil carbon in the top soil of the savannah (0–5 cm), and only 12% when the entire 0–45 cm soil layer was considered. The decrease in CSL with time after plantation was more than compensated by an increase in Eucalyptus-derived carbon, and half of the newly incorporated Eucalyptus-derived carbon in the top soil was associated with the clay and fine silt fractions in the 14-year-old. stand. Increment in soil carbon after afforestation of tropical savannah with Eucalyptus is therefore expected despite a rapid disappearance of the labile savannah-derived carbon because a large fraction of savannah-derived carbon is stable.

Estimation of carbon storage, carbon inputs, and soil CO2 efflux of alder plantations on granite soil in central Korea: comparison with Japanese larch plantation

Alder is a typical species used for forest rehabilitation after disturbances because of its N2-fixing activities through microbes. To investigate forest dynamics of the carbon budget, we determined the aboveground and soil carbon content, carbon input by litterfall to belowground, and soil CO2 efflux over 2 years in 38-year-old alder plantations in central Korea. The estimated aboveground carbon storage and increment were 47.39 Mg C ha−1 and 2.17 Mg C ha−1 year−1. Carbon storage in the organic layer and in mineral soil in the topsoil to 30 cm depth were, respectively, 3.21 and 66.85 Mg C ha−1. Annual carbon input by leaves and total litter in the study stand were, respectively, 1.78 and 2.68 Mg C ha−1 year−1. The aboveground carbon increment at this stand was similar to the annual carbon inputs by total litterfall. The diurnal pattern of soil CO2 efflux was significantly different in May, August, and October, typically varying approximately twofold throughout the course of a day. In the seasonally observed pattern, soil CO2 efflux varied strongly with soil temperature; increasing trends were evident during the early growing season, with sustained high rates from mid May through late October. Soil CO2 efflux was related exponentially to soil temperature (R2 = 0.85, P < 0.0001), but not to soil water content. The Q10 value for this plantation was 3.8, and annual soil respiration was estimated at 10.2 Mg C ha−1 year−1.

Short-term effects on soil properties and wheat production from secondary paper sludge application on two Mediterranean agricultural soils

This study was conducted under greenhouse conditions to evaluate the potential use of SPS as a fertilizer, amendment and/or liming agent for wheat ( Triticum aestivum L.). Two representative Mediterranean agricultural soils, a Cambic Arenosol (cmAR) and a Cromic Cambisol (crCM) were used. Treatments included four sludge rates ranging from 0 to 40 g kg −1 (equivalent of 0, 38, 88 and 120 Mg ha −1). A significant increment in soil pH, organic carbon, N total, available P and exchangeable K were observed in both soils. Sludge application significantly increased N and decreased Zn, Mn and Cu concentrations in wheat. Wheat grain yields were reduced by 33% and 37% when 120 Mg SPS ha −1 was applied to cmAR and crCM soils, respectively, due apparently to unavailability of Mg. However, straw yields, with much lower Mg requirements, increased significantly with SPS rates. Secondary pulp mill sludge seems to be a potential source of organic matter, N, P, K and a potential soil amendment liming agent for acid soils, when appropriate supplemental fertilizer was provided. For grain crops grown in these soils, addition of Mg is required for proper nutrient balance.