Base Cations Research Articles

Land suitability assessment for agricultural crops in Enrekang, Indonesia: combination of principal component analysis and fuzzy methods

<p>Land suitability assessment is essential for the efficient use of diminishing fertile agricultural land. Assessment parameters include soil texture, pH, the sum of basic cations, base saturation, cation exchange capacity, organic carbon, soil depth, slope, and mean annual temperature and precipitation data. Results showed that 76.28% and 23.26% of the total area were optimally and moderately suitable for coffee growth, respectively; 9.6% and 90% were optimally and moderately suitable for cocoa growth, respectively; 1.98%, 78.74%, and 19.26% were optimally, moderately, and marginally suitable for clove growth, respectively; and 6.68%, 86.89%, and 6.41% was optimally, moderately, and marginally suitable for pepper growth, respectively. The final land suitability index (LSI) was strongly influenced by the threshold values used by the researcher and the quality of the land indicator itself. Plant threshold values differed due to variations in plant recruitment. The main limiting factors were mean annual temperature <26°C, acidic soil pH, and low CEC. This study showed that the fuzzy method is ideal for converting the numerical data of various magnitudes into membership function values and representing land suitability. The principal component analysis is an effective method to determine the weights of multiple factors in a systematic and objective manner. The linearity test found a correlation between LSI and production with f = 0.00, indicating that the applied model can predict agricultural production and is applicable to other agricultural land management.</p>

The Impact of Partial Deforestation on Solute Fluxes and Stream Water Ionic Composition in a Headwater Catchment

To ensure the good chemical status of surface water across Europe, it is necessary to increase research on the comprehensive impact of land use and land cover changes, i.e., deforestation, on the natural environment. For this reason, we used data from 9-year environmental monitoring in the Wüstebach experimental catchment of the TERENO (Terrestrial Environmental Observatories) network to determine the impact of partial deforestation on solute fluxes and stream water ionic composition. In 2013, a partial deforestation experiment was conducted in the study area using a cut-to-length logging method. To this end, two headwater catchments were compared: one partially deforested (22% of the catchment area) and one untreated control catchment. The concentrations of ions in stream water, groundwater, and precipitation were analyzed: Ca2+, Mg2+, Na+, K+, Al3+, Fetot, Mn2+, NO3−, SO4−, and Cl−. Most of the ions (Na+, Ca2+, Mg2+, Cl−, and SO4−) showed decreasing trends in concentrations after deforestation, indicating a dilution effect in stream water due to the reduction of the supply of solutes with precipitation in the open deforested area. The fluxes of these ions decreased by 5–7% in the first year after deforestation, although the stream runoff increased by 5%. In the second year, the decrease in ion fluxes was greater, from 6% to 24%. This finding confirms that only limited soil erosion occurred after the deforestation because the soil was well protected during logging works by covering harvester lanes with branches. Only K+ and NO3− ions showed increasing trends in both concentrations and fluxes in the partially deforested catchment in the first two to three years after deforestation. Spruce die-offs, common in Europe, may decrease the concentration and fluxes of base cations in surface water in a nutrient-limited environment. However, the simultaneous planting of young broad-leaved trees with post-harvesting regrowth could create a nutrient sink that protects the catchment area from nutrient depletion.

Assessment of potential mobility of selected micropollutants in agricultural soils of the Czech Republic using their sorption predicted from soil properties

The sorption of organic contaminants in soils and sediment is a crucial factor affecting their mobility in the vadose zone environment. The Freundlich sorption isotherms were evaluated for eleven micropollutants and eight soils. The highest Freundlich sorption coefficients, KF, were obtained for triclosan (324 ± 153 cm3/nμg1–1/ng−1) followed by sertraline (120 ± 74), venlafaxine (74.3 ± 41.2), telmisartan (33.3 ± 13.6), atorvastatin (8.66 ± 4.78), bisphenol S (8.03 ± 4.87), lamotrigine (6.92 ± 3.02), 2-phenylbenzimidazole-5-sulfonic acid (3.77 ± 2.25), memantine (3.42 ± 1.64), 1-methyl-1H-benzotriazole (2.05 ± 0.99), and valsartan (0.88 ± 0.89). The KF values for the individual compounds were correlated with soil properties. Multiple linear regressions were used to derive equations for predicting the KF values using the soil properties. The first set of equations contained mainly properties with the strongest correlations with the KF values, e.g., a base cation saturation for positively charged compounds or a hydrolytic acidity for negatively charged compounds. The second set of equations contained properties included in the map of agricultural soils of the Czech Republic. These equations always indicated positive correlations with oxidizable organic carbon and clay content. They also included either a negative or positive correlation with pHKCl. A positive correlation with pHKCl was obtained for venlafaxine, memantine, and sertraline, which were mostly positively charged. A negative correlation with pHKCl was obtained for the remaining compounds. The second set of equations, the soil map, and the database of soil properties were used to predict the KF value distributions within the Czech agricultural soils. It resulted in similar KF distributions' patterns for valsartan, lamotrigine, atorvastatin, and telmisartan (with a positive correlation between KF and hydrolytic acidity), which considerably differed from the KF patterns for the other compounds. These maps were used to delineate areas with a leaching potential of the compounds toward groundwater that will serve as a tool for assessing a potential groundwater vulnerability.

ЛЕЙКОЦИТЫ И ТРОМБОЦИТЫ ПЕРИФЕРИЧЕСКОЙ КРОВИ ТЮЛЬКИ ЧЕРНОМОРСКО-КАСПИЙСКОЙ (CLUPEONELLA CULTRIVENTRIS, NORDMANN 1840) ИВАНЬКОВСКОГО И УГЛИЧСКОГО ВОДОХРАНИЛИЩ

For the first time, the hematological parameters of tyulka (Clupeonella cultriventris, Nordmann, 1840) in the reservoirs of the Upper Volga were studied. The composition of leukocytes and thrombocytes, morphometric characteristics of cells were studied by routine methods of light microscopy. It was shown that blood of tyulka has a lymphocytic character, but an increase in the number of granulocytes and their size was found against the background of a decrease in the number of lymphocytes in tyulka a in the lower section of the Ivankovo ‒ the upper section of the Uglich reservoirs, which may indicate the presence of anthropogenic pressure. The proportion of thrombocytes was approximately three times higher than the proportion of leukocytes, which indicates a high blood clotting of the tyulka. Correlations between the characteristics of leukocytes and platelets and the content of basic cations and anions in water were studied.

A Case Study of a 10-Year Change in the Vegetation and Water Environments of Volcanic Mires in South-Western Japan

Variations in the groundwater environments and dominant species of volcanic mire vegetation were monitored for 10 years in a volcanic area in south-western Japan. The correlation between changes in groundwater environments and vegetation revealed that changes in water environments determine the dominant species of volcanic mire vegetation. The amount of spring water supplied to the mire vegetation determines the water-table depth and the subsequent nutrient supply. The Sphagnum spp. coverage decreased with increasing base cation concentrations, particularly the Ca2+ concentration up to 40 mg/L. The Moliniopsis japonica coverage increased with the decreasing Sphagnum spp. coverage. The nutritional variables of water supplied to vegetation affected by volcanic activity changed the type of dominant species. A 10-year change in vegetation in the volcanic mires revealed that vegetation succession in volcanic mires evolved from ombrogenous to minerogenous and from minerogenous to ombrogenous communities. The water environment promoted changes in the dominant species.

Integrated approach for the investigation of groundwater quality through hydrochemistry and water quality index (WQI)

Evaluation of groundwater quality and their controlling processes are very important for the sustainable utilization of groundwater in any region. In the present study, 100 groundwater samples were collected during pre-monsoon and post-monsoon 2019 from the tube well and public water supply wells in Mewat district, Haryana to investigate the water quality for drinking purposes and their controlling hydrogeochemical processes through an integrated approach. Different methods like conventional hydrogeochemical analysis, ion ratio plots, and water quality index (WQI) were applied. The results showed that the groundwater of Mewat is highly saline, with the average concentration of total dissolved solids (TDS) during the pre-monsoon (PRM) and post-monsoon (POM) being 4435 mg/L and 4938 mg/L, respectively. Statistical results revealed that anion concentrations follow the order as Cl− > SO42− > HCO3− > NO3− while cation concentrations were Na+ > Ca2+ > Mg2+ > K+. The dominant hydrochemical types of Mewat groundwater were identified to be Ca2+.Mg2+- SO42−.Cl− and SO42−.Cl−- Na+. Silicate weathering, evaporation, and cation exchange were the three factors that control the composition of groundwater of Mewat. The chloro-Alkali indices indicate the dominance of direct base cation exchange reaction in the study area. Moreover, the results of the water quality evaluation showed that the values of WQI ranged from 72 to 3683 and 51 to 2451 during PRM and POM, respectively. WQI classes, namely Very poor and Poor water for drinking, are cumulatively represented by 64% and 58% of the total samples over the PRM and POM. And groundwater of Mewat was found mostly not suitable for drinking purposes. This is the first work in the Mewat district to assess the groundwater quality using WQI and their controlling hydrogeochemical process. This study provides insight into fundamental processes and aquifer controlling factors that are significant for the sustainable management of Mewat groundwater resources.

Protection of forest ecosystems in the eastern United States from elevated atmospheric deposition of sulfur and nitrogen: A comparison of steady-state and dynamic model results

Critical loads (CLs) and target loads (TLs) of atmospheric deposition of sulfur (S) and nitrogen (N) specify the thresholds of air pollution above which damage to ecosystems is expected to occur and are used to inform environmental regulation and natural resource management. Model estimates of CL and TL can vary for a given location, and these differences can be important for characterization of ecosystem effects from elevated S and N deposition. Moreover, TLs are used to evaluate associated timeframes of ecosystem recovery. We compared published CLs and TLs based on soil acidity criteria derived from steady-state versus dynamic models for terrestrial ecosystems. We examined the magnitude of differences in the CL/TL results from the two types of models for the same regions in the Eastern U.S. Results showed that CLs/TLs from dynamic models (or from steady state modeling using soil base cation weathering estimates from dynamic models) generally produce a broader range of values of acid-sensitivity, including lower CLs/TLs, as compared with a steady-state approach. Applications of dynamic biogeochemical models capable of developing CLs/TLs are relatively data intensive and typically limited to locations where measured soil and soil solution (or nearby stream water) chemistry are available for model parameterization, calibration, and testing. We recommend that CLs/TLs derived from dynamic models be used, where data permit, as they are likely more accurate and allow for evaluation of time-dependent phenomena and period needed for recovery. However, CLs derived from steady-state models remain a useful tool for understanding broad spatial patterns in soil acid-sensitivity throughout the U.S. Future work should focus on the development of more reliable model input parameters, particularly soil base cation weathering, and the extent to which CLs and TLs at a given location may vary and be altered with anticipated future climate change. In addition, dynamic models could be further developed to estimate CLs/TLs for nutrient N.

Base saturation is an inadequate term for Soil Science

Bases are chemical species that donate electrons, accept protons, or release hydroxyls (OH–) in aqueous solution. In Soil Science, “base saturation”, “exchangeable bases” or “basic cations” has been widely used to distinguish Ca2+, Mg2+, Na+, and K+ from H+ and Al3+ cations. This terminology is confusing since none of these cations are truly a base in chemistry sense. However, in the absence of the proposition of a correct term, the term “base saturation” remains in use nowadays, causing confusion [...]

Long-term changes in soil composition in unmanaged central European mountain spruce forests after decreased acidic deposition and a bark beetle outbreak

We studied the effect of tree mortality on nutrient concentrations and pools in soils of two unmanaged mountain forest catchments (Plešné, PL; and Čertovo, CT; Czech Republic) recovering from acidification due to decreasing acidic atmospheric deposition since the late 1980s. Both catchments were situated at similar elevation, and before a bark beetle outbreak were covered by healthy mature Norway spruce (Picea abies) forests. However, differing bedrock [granite (PL) vs mica-schist and quartzite (CT)] resulted in lower concentrations of base cations (except for magnesium), but higher concentrations of aluminium and iron oxyhydroxides in the CT soils, enabling higher phosphorus (P) accumulation. Despite these differences, soils were similarly acidic, with pHH2O from 3.5 to 4.3 and cation exchange capacity (CEC) dominated by exchangeable protons (H+ex) and aluminium in both catchments in 2000. In the PL catchment, >75 % of mature spruce trees died after a bark beetle infestation between 2004 and 2008, and all dead biomass was left on site. Forest damage in the CT catchment was minor. Soil concentrations and pools of exchangeable calcium (Ca2+ex), magnesium (Mg2+ex), potassium (K+ex), and H+ex were tightly related to concentrations of organic carbon (C). Following the tree dieback in the PL catchment, we observed significant (p < 0.05) increases in (1) concentrations and pools of Ca2+ex, Mg2+ex, and K+ex, (2) base saturation (from 30 to ∼ 40 %), (3) CEC:C ratios (i.e., CEC of soil organic carbon), (4) pHH2O, (5) mineral P forms, and (6) total nitrogen (N) in the upper (O and A) soil horizons. Similar changes were less pronounced or negligible in the less impacted CT soils. The elevated litterfall after tree dieback, resulting in the increased input of base cations to forest floor and increased CEC of soil organic C, played a more important role in the decreasing acidity of the PL soils than the continuing decrease in acidic deposition.

Hydrologic regulation of clay-mineral transformations in a redoximorphic soil of subtropical monsoonal China

Abstract Clay-mineral evolution in supergene environments is commonly a complex process subject to hydrologic influences on clay-mineral transformations, yet these influences remain insufficiently investigated to date. A quaternary red soil profile with evident redoximorphic features in subtropical monsoonal China was investigated with a focus on processes of secondary clay-mineral transformation. Evidence provided by soil physical and chemical descriptions, clay-mineral analysis, spectroscopic characterization, extractions of pedogenic Al and Fe species, and geochemical compositions reveals a complex relationship of clay minerals and iron phases to pedogenic weathering conditions as a function of depth in the studied soil profile. The soil profile can be divided into a homogenous horizon (HH; 0–2.0 m), a redoximorphic horizon (RH; 2.0–6.0 m), and a basal layer (BL; 6.0–7.2 m), and these three horizons are dominated by various intermediate clay phases. The HH is characterized by moderately acidic conditions (mean pH = 5.2) and low total organic content (TOC; TOC ≤2.1 g kg–1). More importantly, compared with the lower horizons, the HH contains significantly more active acid-forming cations, as reflected by a greater abundance of Al phases and higher aluminum saturation levels. We infer that the occurrence of hydroxy-interlayered vermiculite (HIV) in the HH is tightly coupled with the nature of the soil acidic pools, which include both H+ ions (i.e., pH) and active acid-forming cations (e.g., Al3+ and Fe3+). The reaction pathway from primary minerals to final weathering products appears to be highly sensitive to dynamic hydrological processes. HIV is favored in generally oxic, well-drained soil systems with adequate acidic cations to maintain acidic weathering. When soils are more waterlogged and the aqueous solution is dominated by base cations, primary minerals tend to transform to smectite group minerals. Therefore, discrete smectite, interstratified illite-smectite (I-S), and interstratified kaolinite-smectite (K-S) were observed only in the RH and BL. We present a novel framework that links clay-mineral transformation pathways to soil hydrological disturbances, providing new insights into understanding the kinetics of water-mineral interactions in natural soil systems.

Testing the ‘Vineyard Geologic Identity’ concept in Marquette-producing vineyards in the Champlain Valley, Vermont, USA

ABSTRACT The recently formalized concept of ‘Vineyard Geological Identity’ (VGI) was applied to two vineyards in the Champlain Valley of Vermont, USA. The vineyards studied, LP and SV, both produce the hybrid grape known as ‘Marquette’, are at equivalent elevations, have a similar macroclimate, and were inundated by proglacial Lake Vermont during the last deglaciation. In contrast, the bedrock differs beneath the two sites, and SV was under shallow marine water immediately after Lake Vermont drained. The hypothesis tested was that despite their similar physical settings, the VGI of the two vineyards would vary as a result of differences in their late-Quaternary histories. Samples of soil and sediment were evaluated for grain size distribution, thermogravimetric analysis, mineralogy, major element chemistry, and standard soil fertility assessments, and a map of soil conductivity was made for each site. Results reveal that base cations and silt are significantly more abundant at LP. Conversely, at SV, Na is significantly more abundant, samples are coarser and soil conductivity is higher. These results illuminate the utility of VGI for defining the fingerprint of individual vineyards, and establish a physical foundation for future work evaluating the role of physical setting in controlling aspects of Marquette wines.

Floodplain forest soil series along the naturally wandering gravel-bed river in temperate submontane altitudes

Forest soil series classification is a fundamental approach for evaluating relationships between site conditions and vegetation. This study focused on the characteristics of soil conditions in a floodplain temperate forest through the classification of chemical and hydrophysical properties into trophic and hydric series using a geobiocoenological approach. The characteristics were found on fluvial landforms (FLs) in the natural outer Carpathian gravel-carrying floodplain along the Morávka River (336–383 m a.s.l., Czech Republic). The soil condition series was evaluated through analysis of variance and discriminant analysis. The FLs clearly divide the soil series. The total separability of the trophic series was 84 %, whereas that of the hydric series was 72 %. The separabilities of soil chemical properties were 66–81 % among the FLs, although hydrophysical properties distinguished them only with 41–64 % accuracy. The bar soil series appeared to be alkaline and hydrically limited, in contrast to the terraces. The active floodplain appeared to be alkaline on<68 % of the area, whereas terraces were mesotrophically-nitrophilous to mesotrophic. Nevertheless, the discrepancy between the base saturation and cation exchange capacity suggests soil development intensity on the FLs. Thus, we conclude that the transients between the bar and terrace soil series indicate the differentiation of site conditions for floodplain vegetation development.

A single application of fertilizer can affect semi-natural grassland vegetation over half a century.

Restoration of species-rich semi-natural grassland requires not only a seed source but also appropriate soil properties. In Europe, approximately 10 years are required for the properties of fertilized soils to reach suitable conditions and be considered successfully restored. However, restoration may require additional time in Japan because heavier precipitation causes leaching of basic cations from soils, resulting in soil acidification; volcanic ejecta also forms active Al and Fe hydroxides with high phosphate sorption. Within this context, we aimed to answer the following questions: i) whether and how the impacts of fertilization remain in the soil properties after half a century in Japan; and ii) how fertilization affects the restoration of semi-natural grasslands in Japan. We investigated the vegetation and soil properties of a Zoysia japonica pasture improved half a century ago with a single application of fertilizer and an adjacent semi-natural grassland (native pasture) in Japan, and found the following: (1) the two pastures had similar dominance of Z. japonica, but differed in the species composition; (2) the improved pasture exhibited lower species richness than the native pasture; (3) soil nutrients, including N, P, K, Mg, and Ca, were higher in the improved pasture than in the native pasture; and (4) many chemical properties of the soils were associated with species composition; namely, the vegetation on nutrient-rich soil had more alien species and fewer native species. We conclude that a single dose of fertilization can affect soil properties in semi-natural grasslands over half a century in Japan, leading to species loss and changing the species composition. We suggest that fertilized soils under grazing in Japan may require more than half a century to restore the nutrients to suitable levels for the establishment of a species-diverse grassland.

Biogeochemical shifts and zooplankton responses in post-CAAA northeastern lakes: The success of acid recovery, complexity of biological recovery, and value of long-term monitoring

Lakes in the northeastern U.S., as in other regions, experienced significant declines in water quality and ecosystem health in the mid to late 20th century as atmospheric deposition from industrial emissions caused surface waters to acidify. After the Clean Air Act Amendments of 1990 enhanced regulations to limit emissions of sulfur and nitrogen, many lakes in the Northeast recovered from acidification. The organisms that inhabit lakes are susceptible to these shifts, and zooplankton can serve as valuable indicators of lake ecosystem responses to shifts due to their position as primary consumers in the food web. We evaluated a large historical dataset from the U.S. Environmental Protection Agency (EPA) Eastern Lake Survey (ELS) of 143 lakes throughout the northeastern U.S. to understand how recovery from acidification and subsequent chemical changes influenced zooplankton body size and community composition. We observed significant changes in chemistry; surface water sulfate concentrations decreased by 22% in the ELS lakes between the two sample years of 1986 and 2004. Increasing concentrations of DOC are common from the combined influence of deacidification and climate change, and the ELS lakes experienced a 26% increase in DOC. Notably, in the more developed regions of our study area, chloride concentration in lakes tripled, likely due to increased use of road deicers, and this is related to a subsequent increase in calcium and magnesium base cations. Zooplankton body size increased significantly between 1986 and 2004 across all taxa, and body size of Daphnia species, which require higher amounts of calcium than other zooplankton taxa, was positively associated with high calcium lakes. Shifts in zooplankton community structure, however, were most strongly influenced by variation in ANC, sulfate, and DOC. Our findings indicate that, while surface water acidity has a strong influence on zooplankton community structure, zooplankton populations are likely on a different trajectory than a simple recovery due to multiple chemical changes, such as increased chloride, occurring in lakes undergoing acid recovery. These, along with changes in climate and land-use, elicit multiple simultaneous responses in zooplankton communities.

Tracing changes in base cation sources for Arctic tundra vegetation upon permafrost thaw

Upon permafrost thaw, the volume of soil accessible to plant roots increases which modifies the acquisition of plant-available resources. Tundra vegetation is actively responding to the changing environment with two major directions for vegetation shift across the Arctic: the expansion of deep-rooted sedges and the widespread increase in shallow-rooted shrubs. Changes in vegetation composition, density and distribution have large implications on the Arctic warming and permafrost stability by influencing the albedo, the snow accumulation and the litter decomposition rate. A better understanding of these cumulated effects of changing vegetation on warming and permafrost requires assessing the changes in plant nutrient sources upon permafrost thaw, nutrient access being a limiting factor for the Arctic tundra vegetation development. In this study, we determined the influence of permafrost degradation on the base cation sources for plant uptake by using the radiogenic Sr isotope ratio as a tracer of source, along a permafrost thaw gradient at Eight Mile Lake in Interior Alaska (USA). As plants take up Sr from the exchangeable soil fraction with no measurable fractionation, we determined the differences in 87Sr/86Sr ratio of the exchangeable Sr between shallow and deeper soil horizons, and we compared the 87Sr/86Sr ratio of foliar samples for three Arctic tundra species with contrasted rooting depths (Betula nana, Vaccinium vitis-idaea, and Eriophorum vaginatum) upon different permafrost thaw conditions. The higher foliar 87Sr/86Sr ratios of shallow-rooted Arctic tundra shrubs (B. nana, V. vitis-idaea) was consistent with a shallow source of soil exchangeable Sr from surface soil horizons, whereas the lower foliar 87Sr/86Sr ratios of deep-rooted Arctic tundra sedges (E. vaginatum) reflected a source of Sr from deeper soil horizons. There is a shift between poorly and highly thawed soil profiles towards lower foliar 87Sr/86Sr ratios in both deep- and shallow-rooted plant species. This shift supports that micro-landscape variability in the exchangeable base cation reserve with soil depth represents a key source of readily available nutrients for both shallow- and deep-rooted plant species upon permafrost thaw. This study highlights a key change in plant nutrient source to consider upon thaw. This finding lies beyond the common view that nutrient release at the permafrost thaw front preferentially benefits deep-rooted plant species.

Plant species diversity is driven by soil base cations under acid deposition in desert coal-mining region in northwestern China

Given that the rate of acid deposition tends to be stable or even decline in most regions of China, the rapid development of the coal industry accelerated the rates of S and N deposition in Northwest China. Although desert plants are sparse, they play an essential role in maintaining ecosystem functions. However, few studies have evaluated whether and how acid deposition affects plant species diversity in deserts, especially those with moderate and severe alkalinity. In this study, three coal-fired power plants located at the Ningdong Energy and Chemical Industry Base in Northwest China were selected as the monitoring sites. From 2019 to 2021, we analyzed the chemical compositions of the bulk deposition of rainfall and dustfall, plant species diversity, and the main factors influencing plant diversity along a 2000 m sampling distance gradient. There were no apparent trends in annual deposition of SO42− (19.67–82.28 kg ha−1 yr−1), NO3− (2.83–11.42 kg ha−1 yr−1), NH4+ (1.91–5.20 kg ha−1 yr−1), and inorganic N (4.91–16.11 kg ha−1 yr−1) along the sampling gradient. The SO42− deposition was lower than the S deposition critical load in the study area, whereas the N deposition exceeded the acceptable N deposition of soils. The base cation (BC) neutralized the input acidity of the bulk deposition, in which Ca2+ played a key role. There were no significant differences in the Patrick richness index (2–8), Shannon-Wiener diversity index (0.45–1.73), and Pielou evenness index (0.56–0.99) along the sampling gradient, whereas an increasing trend was observed in the Simpson dominance index (0.13–0.72). C:N:P ecological stoichiometry in plant–microbe-soil could not highly explain the variation in plant diversity. S, N, and BC deposition had minor direct effects on plant diversity. However, S and BC deposition could indirectly influence plant diversity through their influence on soil BCs and bulk deposition pH. The results indicate that S deposition increases bulk deposition acidity, reduces soil BC concentration, and improves soil alkaline environments, thus enhancing plant diversity in the studied deserts. Current N deposition does not greatly affect plant diversity. However, long-term observations are still required to thoroughly evaluate the effect of N deposition..

δ26Mg, δ44Ca and 87Sr/86Sr isotope differences among bedrock minerals constrain runoff generation in headwater catchments: An acidified granitic site in Central Europe as an example

Magnesium, calcium and strontium isotope systematics were studied in a Central European headwater catchment underlain by granite. The Uhlirska catchment (Czech Republic) is recovering from acidification following 40 years of acid rain. A combination of isotope and non-isotope data was used to constrain the origin of base cations in runoff. Whole-rock δ26Mg, δ44Ca values and 87Sr/86Sr ratios were complemented by isotope analysis of apatite, biotite, plagioclase, orthoclase and titanite. Isotope composition of Mg, Ca and Sr in precipitation, throughfall and runoff was monitored for 12 months.Soil, soil solutions and Norway spruce tissues were also analyzed. Non-isotope data included a 24-year time-series of input/output Mg and Ca fluxes. Biotite was the likely main source of geogenic Mg. Apatite and plagioclase were the likely main sources of geogenic Ca, and plagioclase was the likely main source of geogenic Sr. Magnesium in biotite was isotopically too heavy to dominate runoff. Calcium in apatite and plagioclase was isotopically indistinguishable from whole-rock Ca and could play a major role in runoff generation. Plagioclase had a significantly lower 87Sr/86Sr ratio than bulk bedrock, close to the low 87Sr/86Sr ratio of runoff. Plagioclase weathering was consistent with a sizeable geogenic Sr contribution to runoff but if only bulk-rock 87Sr/86Sr was considered predominance of geogenic Sr in runoff would be unlikely. Higher Mg, Ca and Sr runoff fluxes, compared to deposition, suggested geogenic control of runoff. A decrease in runoff fluxes of Mg and Ca coincided with a decrease in deposition fluxes but there may not be a causal relationship pointing to a large atmospheric contribution of base cations to runoff. Decreasing fluxes of base cations via runoff were mostly related to decreasing sulfate export accompanying retreat of acidification. Mg/Ca/Sr isotope systematics at Uhlirska are discussed in light of analogous data from four other headwater catchments.

Geochemical and mineralogical processes leading to variation of soil characteristics on calcareous toposequence in semiarid ecosystem condition

Soils are under the influence of their formation processes at varying rates. Determining the variability and characteristics of soils due to the formation processes’ effects is vital for sustainable soil management. This study aimed to investigate soils formed on limestone and on different physiographic units (summit, shoulder, backslope and footslope) under semiarid climatic condition. That is why, the present study assessed clay mineralogy, weathering indices, mass loss/gain states, and physic-chemical properties of different profiles. It is concluded that smectite clay mineral is dominant in the profile IV located on footslope position with differences in clay mineralogy due to physiographical change. The summit physiographic unit includes the highest aggregate stability (63.74%). The soil’s field capacity and wilting point contents showed statistically significant variation with the increase in smectite clay minerals in the PIV profile on the footslope unit (p < 0.01). In addition, a positive (0.506; p < 0.05) directional relationship was found between the variability in physiographic units (from summit to footslope) and the available water content (AWC). In addition, bulk density and porosity characteristics varied depending on the particle size distribution and land use type. The soils formed on shoulder and backslope units classified as Entisol soil order are described as “not decomposed” according to the Chemical Alteration Index (CIA), Chemical Weathering Index (CIW), and Plagioclase Alteration Index (PIA) values. On the other hand, in the Inceptisol and Vertisol soils, it was determined leaching process for basic cations in the PI and PIV profiles located on the summit and footslope. As for mass balance system, the highest losses from the soil formed on the backslope whereas, the PI and PIV formed on the footslope position gains. As a result of this study, it has been revealed that soil formation process in the summit and footslope is more effective than in other physiographic units. Therefore, physico-chemical properties are mainly affected by these processes.

Long-Term Organic Inputs Determine Soil Productivity Better in Sorghum-Cowpea Rotation Than in Sorghum Monoculture

Information on long-term fertilization combined with crop rotation can contribute to better management of West African Lixisols. There is little information on how long-term organic inputs influence soil chemical properties under cereal monoculture versus a rotation with a legume. Here, we investigated how fertilization regimes with emphasis on organic inputs influence soil chemical properties in sorghum monoculture compared to sorghum-cowpea rotation. The long-term field trial of Saria in Burkina Faso, which has been in operation since 1960, was used for this purpose. Soils were sampled at the 0-20 cm depth to determine their organic C, total N, total P, mineral N, available P, pHwater, exchangeable basic cations, and cation exchange capacity. The best soil properties were exhibited with the application of 40 t ha-1 of manure. Recycling of sorghum residues combined with mineral fertilization led to a decrease in mineral N and available P but maintained a higher level of total N and P compared to exclusive mineral fertilization. Organic inputs determined soil properties and sorghum yield better (R2 = 0.89) in rotation than in monoculture. Our results show that a better productivity of the studied Lixisol requires an application of manure at more than 5 t ha-1 combined with mineral fertilization. In addition, a rotation including a legume and a regular recycling of crop residues is necessary.

Wet depositions of cations in forests across NADP, EMEP, and EANET monitoring networks over the last two decades

Studies focused on emissions and acid deposition of sulfur (S) and nitrogen (N) and the consequent precipitation acidity have a long history. However, atmospheric depositions of cations play a critical role in buffering precipitation acidity, and providing cationic nutrients for vegetation growth lacks sufficient studies equally. The spatiotemporal patterns of cation depositions and their neutralization potential across broad scales remain unclear. Through synthesizing the long-term data in forest sites (n = 128) derived from three monitoring networks (NADP in Northern America, EMEP in Europe, and EANET in East Asia) on wet deposition of cations (Na+, NH4-N, K+, Mg2+, and Ca2+), this study assesses the temporal changes and spatial patterns of cation depositions and their neutralization potential over the last two decades. The results showed that the depositions of cationic nutrients were considerably higher in EANET compared to NADP and EMEP. The depositions of sea salt-associated sodium exhibited a significant transition from marine (> 15 kg ha−1 year−1) to inland (< 3.0 kg ha−1 year−1) forest sites attributable to the precipitation quantity and influences of sea spray. The higher emissions of NH3 and particulate matter in East Asia explained the higher cation depositions in EANET than NADP and EMEP. The annual trends of cations revealed that only 20–30% of the forest sites showed significant changing trends and the sites widely spread across the three networks. Possibly, base cation (BC) deposition has reached a low and stable condition in NADP and EMEP, while it has high spatial heterogeneity in the temporal change in EANET. The difference in BC deposition among the three networks reflects their distinct development of economy. Our synthesis indicates that the annual trends of neutralization factor (NF) in NADP can be explained by the declining of acid potential (AP), not by neutralization potential (NP) as BC deposition has been stably low over the past two decades. Whereas, the concurrent decreases of AP and NP in EMEP or plateau period of both AP and NP in EANET have come to a standstill of acid neutralizing capacity.