Extractable Cations Research Articles

Mapping of Water and Soil Quality Parameters in the Gampaha-Ihalagama East and Eldeniya East Grama Niladhari Divisions, Sri Lanka

Water and soil are important natural resources, and the study of their distribution is of great interest. The Grama Niladhari Divisions, Ihalagama-East and Eldeniya-East, located in the Gampaha district, are selected as the study areas, and this is done as a pilot study. Different water and soil quality parameters are investigated followed by the construction of contour maps. As water quality parameters, pH, conductivity, phosphate content, nitrate content, and Ca2+ hardness were determined, and as soil quality parameters, pH, nitrate, organic matter, water-soluble Na+ and K+, extractable Na+ and K+, and water-soluble Ca2+ ion contents were determined. The pH of water samples lies within the range of 4.41 - 7.11 and 3.79 – 7.18 in the Ihalagama-East and Eldeniya East divisions, respectively. Almost all the samples have acidic pH values, with some falling below the lower limit of the WHO guidelines for safe drinking water (6.5 - 8.5). Conductivity values vary from 52.0 - 277.0 µS/cm and between 54.0 – 403.0 µS/cm, respectively, which is below the WHO permissible level of 1500 µS/cm. The phosphate content varies from 1.374 - 3.986 mg/L in Ihalagama-East and water-soluble phosphate was not detected in Eldeniya-East, indicating a very low range and suggesting that the water samples are less contaminated with phosphate-containing substances. Considerably high values in the range of 1.24 - 279.00 mg/L for Ihalagama-east and 59.5 mg/L - 168.0 mg/L for Eldeniya-East, are obtained for the nitrate content where most of them are beyond the safe level of drinking water, 50 mg/L. The soil pH in all the samples falls within the acidic range, varying from 2.99 - 6.73 in Ihalagama-East and 3.07 – 6.68 in Eldeniya-East. Most of the soil samples contain high nitrate contents, indicating significant contamination. The percentage soil organic matter content varies between 0.60% and 13.27% in both areas. Many fertile agricultural soils typically have an organic matter content ranging from 3% - 6% revealing that most of the samples are beyond the standard levels. The distribution of water-soluble and extractable cations does not exhibit a wide range. According to the findings, though two Grama Niladhari Divisions are selected, they also display a huge variation. This reveals the importance of mapping to address contaminations, effects of natural disasters which lead to changes in the studied water and soil quality parameters.

Effects of different fertilization patterns on soil improvement and vegetation restoration of desertified grassland in northwest Liaoning Province, China

Improving soil fertility is one of the key approaches for ecological restoration of the wind-sand area in northwest Liaoning Province. Taking wind-sand area in northwest Liaoning Province as test object, we conducted a fertilization experiment with treatments of inorganic fertilizer (nitrogen, phosphorus and potassium fertilizers), organic fertilizer, combined application of organic and inorganic fertilizers, and organic fertilizer combined with a biologically organic matrix (γ-polyglutamic acid), and no fertilizer as control. We measured soil organic matter content and extractable cations concentrations, vegetation coverage, and biomass under different fertilization treatments and determine the suitable fertilization mode. The results showed that compared to the control, inorganic fertilizer rapidly increased vegetation coverage and biomass, but high levels of inorganic fertilizer (150 kg N·hm-2) led to soil acidification and Ca2+ leaching. Organic fertilizer increased soil organic matter content, exchangeable K+, Ca2+, and Mg2+ contents, as well as coverage and biomass vegetation, especially combined with γ-polyglutamic acid. Overall, the combination of low levels of inorganic fertilizer (50 kg N·hm-2) and moderate levels of organic fertilizer (30000 kg·hm-2) was the best fertilization practice for the rapid and stable restoration of grassland in wind-sand area. Moreover, the extra addition of γ-polyglutamic acid (60 kg·hm-2)could effectively improve soil fertility.

Physico-chemical properties and toxicity of young proglacial soils in the Tropical Andes and Alps

New soils formed after glacier retreat can provide insights into the rates of soil formation in the context of accelerated warming due to climate change. Recently deglacierized terrains (since the Little Ice Age) are subject to weathering and pedogenesis, and freshly exposed sediments are prone to react readily with the environment. This study aims to determine the impact of parent material and time on soil physical and chemical properties of nine proglacial landscapes distributed in the Tropical Andes and Alps. A total of 188 soil samples were collected along chronosequences of deglacierization and from sites that differed in terms of parent material and classified following three parent material groups: (1) Granodiorite-Tonalite (GT), (2) Gneiss-Shales-Schists (GSS), and (3) Mont-Blanc Granite (MBG). We determined physical and chemical soil properties such as contents of clay, silt, sand, organic carbon, bulk density (BD), pH, extractable cation (exCa, exMg, exK), elemental composition by X-ray fluorescence (Al, Si, P, S, K, Ca, Mn, Fe, Cu, Zn, As, Mo, Hg, Pb) and ICP-MS (Al, Ca, Cu, Fe, K, Mg, Mn, Mo, Na, P, S, Zn), and mineral phase (XRD diffraction analysis). Parent material-controlled particle-size distribution, SOC, pH, available P, exCa, and exMg, whereas time since deglacierization only affected SOC and P, and exMg globally. Most of the significant differences in soil properties between parent material groups occurred within the first 17 years after deglacierization, and then we observed a homogenization between sites. While the higher SOC and P contents observed within the GT Andean sites might be due to the parent material composition leading to faster initial soil formation, we identified potential As, Cu, Mo, and Mn toxicity within those soils. Our study highlights the need to investigate further proglacial soil’s buffering capacity and carbon sequestration to globally inform the conservation and management of novel proglacial ecosystems.

Enhanced Nitrogen Fertilizer Input Alters Soil Carbon Dynamics in Moso Bamboo Forests, Impacting Particulate Organic and Mineral-Associated Carbon Pools

The application of nitrogen fertilizer is crucial in the cultivation of bamboo forests, and comprehending the alterations in soil organic carbon (SOC) due to nitrogen application is essential for monitoring soil quality. Predicting the dynamics of soil carbon stock involves analyzing two components: particulate organic carbon (POC) and mineral-associated organic carbon (MAOC). This study aimed to investigate the impact of high nitrogen inputs on SOC stock in Moso bamboo forests located in southwestern China. The research focused on analyzing changes in soil chemical properties, SOC content, and its components (POC and MAOC), as well as microbial biomass in the surface layer (0–10 cm) under different nitrogen applications (0, 242, 484, and 726 kg N ha−1 yr−1). The results indicate that nitrogen application significantly reduced the SOC content, while concurrently causing a significant increase in POC content and a decrease in MAOC content within the Moso bamboo forest (p < 0.05). The HM treatment notably increased the NO3−-N content to 2.15 mg/kg and decreased the NH4+-N content to 11.29 mg/kg, although it did not significantly influence the microbial biomass carbon (MBC) and nitrogen (MBN). The LN and MN treatments significantly reduced the MBC and MBN contents (71.6% and 70.8%, 62.5% and 56.8%). Nitrogen application significantly increased the Na+ concentration, with a peak observed under the LN treatment (135.94 mg/kg, p < 0.05). The MN treatment significantly increased the concentrations of Fe3+ and Al3+ (p < 0.05), whereas nitrogen application did not significantly affect Ca2+, Mg2+ concentration, and cation exchange capacity (p > 0.05). Correlation and redundancy analyses (RDAs) revealed that the increase in annual litterfall did not significantly correlate with the rise in POC, and changes in extractable cations were not significantly correlated with the decrease in MAOC. Soil nitrogen availability, MBC, and MBN were identified as the primary factors affecting POC and MAOC content. In conclusion, the application of nitrogen has a detrimental impact on the soil organic carbon (SOC) of Moso bamboo forests. Consequently, it is imperative to regulate fertilization levels in order to preserve soil quality when managing these forests. Our research offers a theoretical foundation for comprehending and forecasting alterations in soil carbon stocks within bamboo forest ecosystems, thereby bolstering the sustainable management of Moso bamboo forests.

Effects of land use types on the depth distribution of selected soil properties in two contrasting agro-climatic zones

The depth distribution of soil properties are governed by several interacting factors including land use types (LUT) and agro-climate (AgC) factors. Yet, there is little information on the effects of LUT, AgC and their combination on soil properties along depth, which this study aimed to investigate. We collected a total of 36 composite soil samples using the manual percussion of a steel core tube layer by layer vertically up to 30 cm in sites representing both highland and lowlands, and analyzed for selected soil properties. A significant main effects of LUT on the depth distribution of bulk density (BD), Ca, Na, K and Cu, and AgC on soil texture, pH, EC, Ca, Na, K, P, Mn, Fe and Cu were noted. The two-way ANOVA analysis also revealed the significant effects of both LUT and AgC on the depth distribution of BD, Na, K, Cu and EC, reflecting their influences on the paths associated to bio-geo-recycling processes. Compared to crop and forestlands, the average SOC and Fe were lower while EC, CEC, Ca, Na, K, P, Mn and Zn were higher in homegarden located in highland than lowland, possibly the acid nature of the highland soil may make the extractable cations available. SOC was not significantly influenced by AgC, LUT and their interaction effect. Based on the Elemental Enrichment Ratio (EER), the SOC was concentrated in the upper surface soil in forest and cropland located both in highland (1.79, 1.33) and lowland (1.80, 1.57), respectively. The reverse propagation pattern SOC depth distribution in soils under homegarden with EER of 0.7 (highland) ad 0.8 (lowland) showed that implementing such system can accelerate carbon sinking and safely store it in subsoil. Also, diversified species composition associated with respective root architectures in the homegarden system, make it an efficient soil nutrient management, which should be widely promoted.

Increased rainfall may place saline/sodic soils on the tipping point of sustainability

Increased rainfall is increasing the risk of the capillary movement of sodium (Na⁺) and other salts from buried marine sediments to the soil surface in the North American northern Great Plains. These salts reduce productivity and resilience while increasing their effect on the environment. Understanding the interactions among management, climate, cropping system, and soil is the first step toward implementing effective management plans. Unfortunately, while much work has been conducted, little is known about the effective management of semiarid dryland saline/sodic soils. This study determined the influence of soil depth on hydraulic conductivity and changes in soil Na⁺ (mg Na⁺ kg^–1 soil) to electrical conductivity (EC_1:1) (dS m^–1) ratio following high spring rainfall in 2019 in three soils. The soil parent materials were Glaciolacrustrine underlaid at a depth of approximately 15 m by marine sediments that contained Na⁺ and other salts. The landscape positions included in the study were a well-drained shoulder, moderately well-drained backslope, and a poorly drained toeslope soil. Based on the soil classification, shoulder and backslope subsoils were not predicted to be salt affected, while the toeslope soil was predicted to contain a natric soil horizon. Rainfall in 2018, 2019, and 2020 was 46, 76, and 37 cm, respectively, and soil cores were collected prior to and following the 2019 high rainfall. Soil cores were separated into the 0 to 7.5, 50 to 57.5, 82.5 to 90, 92.5 to 100, and 105 to 112.5 cm segments. Samples from 2018 were analyzed for soil EC_1:1, pH, ammonium acetate extractable cations, soil particle size, available water at field capacity, drainable porosity, soil bulk density, and saturated hydraulic conductivity. Samples from 2019 were analyzed for EC_1:1 and ammonium acetate extractable Na⁺. Across the sampling sites, shoulder and backslope soils had higher saturated hydraulic conductivities than the toeslope soils. Saturated hydraulic conductivities were negatively correlated to pH (<i>r</i> = –0.55, <i>p</i> &lt; 0.01), the Na⁺ to EC_1:1 ratio (<i>r</i> = —0.66, <i>p</i> &lt; 0.01), extractable Na⁺ (<i>r</i> = —0.56, <i>p</i> &lt; 0.01), and sand content (<i>r</i> = —0.66, <i>p</i> &lt; 0.01), and positively correlated to the silt content (<i>r</i> = 0.65, <i>p</i> &lt; 0.01). A comparison between the saturated hydraulic conductivity and the Na⁺ to EC_1:1 ratio suggests that saturated conductivities approached 0 cm h^–1 when the Na⁺ (mg Na⁺ kg^–1) to EC_1:1 (dS m^–1) ratio exceeded 600. The 2019 high rainfall increased the risk of soil dispersion in the lower soil depths (&gt;82.5 cm). For example, in the shoulder soil at the 105 to 112.5 cm depth, EC_1:1 decreased 0.936 ± 0.254 dS m^–1 from 2018 to 2019, whereas the exchangeable Na⁺ increased 688 ± 283 mg kg^–1 soil. Our findings suggest that a climate change-induced shift in rainfall patterns can increase salinity and sodicity risks in northern Great Plains subsurface soils. Salinity and sodicity risks are expanding into zones not previously identified as at risk, and improving or maintaining the productivity of these soils requires careful planning.

No Evidence that the Valuable Timber Species, Dalbergia Retusa, Enhances Nutrient Cycling and Uptake by Neighboring Timber Species

ABSTRACT The use of native species for timber plantations in the tropics has lately gained interest. Recent studies have shown that native tree plantations can have greater economic, and ecological benefits than non-native plantations. Facilitative nutritional interactions with nitrogen-fixing trees are a common practice used in hopes of enhancing nitrogen input. Dalbergia retusa and Terminalia amazonia are two neotropical species frequently used for timber extraction. In order to understand these species belowground interactions, we worked on 33 plots of the T. amazonia and D. retusa mixtures in the Agua Salud Project Native Species plantations in Panama. The objective of this study was to assess if soil biochemical properties under T. amazonia trees might be influenced by D. retusa in these mixtures. For this, soil samples were collected and analyzed for nitrogen pools, extractable cations and selected phosphorus constituents. Our results showed that nutrient concentrations were not significantly different below D. restusa and T. amazonia trees. Nonetheless, temporal and physicochemical characteristics of the plantation might be influencing the tree performance and should be considered for a better understanding of the nutrient dynamics in native tree plantations.

Evaluating feedstocks for carbon dioxide removal by enhanced rock weathering and CO2 mineralization

Mineralogically complex feedstocks, including kimberlite, serpentinite, and wollastonite skarns, have vast capacities to sequester carbon dioxide (CO2) through enhanced rock weathering and CO2 mineralization. However, only a small reactive fraction of these feedstocks will be accessible for carbon dioxide removal at Earth's surface conditions. We have developed a new method to evaluate the reactivity of mineral feedstocks that consists of a batch leach test using CO2 coupled with total inorganic carbon (TIC) analysis to quantify easily extractable Mg and Ca from non-carbonate (desirable) cation sources. Kimberlite residues from the Venetia Diamond Mine (South Africa), serpentinites, wollastonite skarn, and brucite ore were tested and the results were compared to those from commercial ammonium acetate (NH4OAc) leach tests. A strong correlation (R2 = 0.99) between leached Ca and TIC showed that carbonate minerals (e.g., calcite in kimberlite) are a substantial and undesirable source of easily extractable cations that must be excluded in calculating CO2 sequestration potential. Silicate dissolution (e.g., serpentine) was inferred from the strong positive correlation (R2 = 0.94) between Mg and Si concentrations leached from kimberlites and serpentinites. Strong correlations between leached Ca and Si were only detected for wollastonite skarns, whereas Mg leaching from samples with high abundances of brucite showed weak or no relationship to TIC or Si. The ability to distinguish between sources (non-carbonate versus carbonate) of easily extractable cations is necessary to accurately assess CO2 sequestration potential. The maximum CO2 storage capacity of the Venetia kimberlites was 268–342 kg CO2/t, and our leach test estimated an accessible potential in the range of 3–9 kg CO2/t when only accounting for non-carbonate sources. Our CO2 batch leach test is useful to evaluate the reactivity of mineralogically complex feedstocks at Earth's surface conditions for the purpose of carbon dioxide removal.

Effects of Woody Compost and Biochar Amendments on Biochemical Properties of the Wind Erosion Afflicted a Calcareous and Alkaline Sandy Clay Loam Soil

ABSTRACT Calcareous and sandy soils generally have soil fertility problems, and these problems have been revealed to be improved by applying compost and biochar produced from the distinct biomass. However, comparing the effects of compost and biochar originating from the same biomass on soil fertility are still not clearly explained. The comparing impacts of compost and biochar both made from the same biomass on soil fertility status in a wind erosion afflicted calcareous and alkaline sandy clay loam (SCL) soil, were explored using a pot experiment. Compost and biochar were produced from a pioneering Oleaster (Oleaster Angustifolia L.) tree through the windrow composting method and pyrolysis process at 450 °C, respectively. The SCL soil used was treated with compost and biochar at rates of 0%, 1%, 2%, and 4% by weight and thereafter incubated for 2 months. The trial layout was in line with a completely randomized plot design with four replicates. Pursuant to the experimental results, the addition of compost and biochar considerably enriched soil fertility by enhancing soil biochemical properties of SCL soil. SCL soil treated with compost yielded the highest available phosphorous (AP), organic carbon (OC), total nitrogen (TN), NH4 +-N, NO3-N, active carbon (AC), potential mineralizable nitrogen (PMN), soil microbial respiration (SMR), electrical conductivity (EC), CaCO3, extractable cations (Mg, K, Ca, and Na), cation exchange capacity (CEC), and available micronutrients (Mn, Fe, and Zn), which were significantly higher (P < .001) than the SCL soil amended with biochar, suggesting the recalcitrance of biochar on microbial activities. Furthermore, available micronutrients (Mn, Fe, and Zn) were significantly decreased in SCL soil amended with biochar compared with compost amended SCL soil, indicating the sorption potential of biochar. It was concluded that applying Oleaster tree compost is more effective than biochar in improving soil fertility. However, the effects of biochar on carbon sequestration and the findings of this study need to be proven under field demonstration for more conclusive results prior to recommending farmers to apply either compost or biochar in soil management practices.

Biosolid compost amendment increases soil fertility and soybean growth

This study evaluates the effect of soil amendment with biosolid compost with wood shavings and yard trimmings on soil fertility, and soybean (Glycine max) biomass, productivity, nutrient uptake, and potential accumulation of toxic elements, like Pb. Soil from agricultural fields under intense crop production were amended with compost at 0%, 5% and 10% w/w rate, and incubated under controlled conditions before planting. Then, a greenhouse experiment was performed to study soybean growth, physiological indicators of productivity, and antioxidant response (chlorophylls, carotenes, antioxidant power, soluble sugars and proteins), as well as nutrient (Mg, Cu, Mn, and Zn), and Pb accumulation. Moreover, soil nutrient status (pH, cation exchange capacity, organic matter, nitrogen, sulfur, extractable cations, and soil microbial activity) were analyzed. The results showed that compost improved soil fertility and microbial activity, including nodulation in soybean roots. Biomass production was strongly increased; content of chlorophyll, carotenes, sugars, and protein also increased. Grains were produced only in the compost treatments. Compost addition also reduced nutrient deficiencies in leaves and grains, and Pb accumulation in soybean. Our findings contribute with information about the role of biosolid compost in sustainable agriculture: allowing the recovery of soil fertility in agricultural soils under intensive production and, consequently, improvement of crop growth.

Cryptogamic Packed Biofilter as Potential Adsorbent for CO2, NH3, and H2S Impurities from Biogas

The presence of elevated concentrations of carbon dioxide, hydrogen sulfide, ammonia, and trace impurities in biogas affect its caloric value as well as causes corrosion and is extremely toxic. There are various methods in existence for removal of these impurities, but most are chemically based and expensive and are limited in use. In our work, cryptogams (moss) integrated with soil and biochar packed in a filter have been employed for simultaneous removal of CO2, H2S, and NH3, from biogas. Different soil types rich in metallic oxides at different masses of 100 g, 150 g, and 200 g with a fixed mass of moss and biochar were tested in an on-site experiment to determine the removal efficiency (RE) and sorption capacity (SC). The adsorption dynamics of the filters were investigated at two flow rates, 80 ml/min and 100 ml/min, by determining removal efficiency. For the contribution of each substrate, sorption capacity and breakthrough time were determined by considering 5 g of each substrate that made up the filter. The soils with a high content of extractable cations showed excellent adsorption capacity for H2S by about 20 g S/100 g, which was higher than other adsorbents tested. It was found that integrated biofilter made up of bed arrangement of the soil, biochar, and moss plant improved the quality of biogas with SC of 11 g S and RE of 93% for H2S, 72% for NH3, and 68% for CO2.

Soil spatial variation to guide the development of fertilizer use recommendations for smallholder farms in western Kenya

A farm survey was conducted within a 100 km2 sampling block to collect data on the spatial variation in unfertilized maize biovolume and grain yields in relation to soil organic carbon (SOC), total nitrogen, phosphorus and extractable cations. Key soil factors associated with crop performance were identified using stepwise multiple linear regression modelling. The spatial variation of key soil factors and crop performance indicators (CPIs) was described in terms of spatial dependency. An analysis of variance indicated the variation explained by soil types, sampling units, and administrative units. Soil properties displayed high variability with coefficients of variation of in the range of 50% to 89% for extractable nutrients. Grain yield ranged widely from 0.1 to 11.3 t ha−1, with 31% of the variation being accounted for by measured soil properties. SOC was identified as key soil factor associated with variation in crop performance. SOC displayed moderate spatial dependency with a range of 523 m. Analysis of variation indicate that variation in SOC was sufficiently described by small spatial units (fields). These insights were used to provide a framework for determining an appropriate scale for developing digital soil maps or distance for soil sampling in heterogenous smallholder farming systems. Strategies aimed at refining fertilizer use recommendation can therefore use this guideline.

Competing effects of soil fertility and toxicity on tropical greening

Tropical forests are expected to green up with increasing atmospheric CO2 concentrations, but primary productivity may be limited by soil nutrient availability. However, rarely have canopy-scale measurements been assessed against soil measurements in the tropics. Here, we sought to assess remotely sensed canopy greenness against steep soil nutrient gradients across 50 1-ha mature forest plots in Panama. Contrary to expectations, increases in in situ extractable soil phosphorus (P) and base cations (K, Mg) corresponded to declines in remotely sensed mean annual canopy greenness (r2 = 0.77–0.85; p < 0.1), controlling for precipitation. The reason for this inverse relationship appears to be that litterfall also increased with increasing soil P and cation availability (r2 = 0.88–0.98; p < 0.1), resulting in a decline in greenness with increasing annual litterfall (r2 = 0.94; p < 0.1). As such, greater soil nutrient availability corresponded to greater leaf turnover, resulting in decreased greenness. However, these decreases in greenness with increasing soil P and cations were countered by increases in greenness with increasing soil nitrogen (N) (r2 = 0.14; p < 0.1), which had no significant relationship with litterfall, likely reflecting a direct effect of soil N on leaf chlorophyll content, but not on litterfall rates. In addition, greenness increased with extractable soil aluminum (Al) (r2 = 0.97; p < 0.1), but Al had no significant relationship with litterfall, suggesting a physiological adaptation of plants to high levels of toxic metals. Thus, spatial gradients in canopy greenness are not necessarily positive indicators of soil nutrient scarcity. Using a novel remote sensing index of canopy greenness limitation, we assessed how observed greenness compares with potential greenness. We found a strong relationship with soil N only (r2 = 0.65; p < 0.1), suggesting that tropical canopy greenness in Panama is predominantly limited by soil N, even if plant productivity (e.g., litterfall) responds to rock-derived nutrients. Moreover, greenness limitation was also significantly correlated with fine root biomass and soil carbon stocks (r2 = 0.62–0.71; p < 0.1), suggesting a feedback from soil N to canopy greenness to soil carbon storage. Overall, these data point to the potential utility of a remote sensing product for assessing belowground properties in tropical ecosystems.

Nitrogen addition has contrasting effects on particulate and mineral-associated soil organic carbon in a subtropical forest

Increasing atmospheric nitrogen (N) deposition has substantially affected carbon (C) and nutrient cycling in forest ecosystems. However, the responses of different soil organic carbon (SOC) fractions with different turnover rates to N addition are highly divergent, and the underlying mechanisms remain elusive. In this study, we explored the responses of surface soil (0–10 cm) characteristics and microbial communities to six years of experimental N addition (0, 50, 100 and 150 kg N ha−1 yr−1) in a subtropical evergreen broadleaf forest in southern China. Our results showed that N addition led to significant soil acidification (pH from 5.3 to 4.9). Microbial biomass carbon and total microbial, bacterial and fungal abundance (phospholipid fatty acid, PLFA) were reduced by N addition, but extracellular enzymes involved in C, N and phosphorus (P) cycling were not responsive to N addition. Soil extractable Ca2+ concentration was depleted by N addition, while other extractable cations (Fe3+, Al3+, Mg2+, K+, Na+) were not affected. Moreover, N addition did not significantly change the C and N concentration of bulk soil. We further separated the bulk soil into particulate organic matter (>53 μm, POM) and mineral-associated organic matter (<53 μm, MAOM) fractions by wet sieving. Interestingly, C in the POM fraction was significantly increased by N addition, while C in the MAOM fraction was depleted by N addition. Correlation analysis and structural equation modeling results suggested that N addition may suppress microbial decomposition of plant inputs and thus lead to accumulation of C in the POM fraction, while it may reduce the mineral sorption of microbial necromass and products and thus cause depletion of C in the MAOM fraction. Taken together, our results highlighted the vulnerability of soil C in the stable MAOM fraction to N addition, and emphasized the role of soil metals (particularly extractable Ca2+) and pH in controlling soil C storage under N addition.

Yield and fruit quality response of PGPR, bulky and folk liquid manures on capsicum (Capsicum annuum L.) in Western Himalayas of India

This paper describes the effect of PGPR, folk liquid manures (Panchagavya, Jeevamrut, Amritpani), bulky and concentrated organic manures (Vermicompost and Poultry manure) under Capsicum in mid hills of Western Himalayas during kharif season of year 2016 at research farm, Department of Soil Science and Water Management, Dr YSPUHF, Nauni, Solan, India. There were 7 treatments of the research trial and the treatment T2 (90% Recommended dose of nutrients with PGPR and liquid manures- Panchagavya, Jeevamrut, Amritpani) recorded maximum plant height (58.3 cm), plant biomass (65.87 g plant-1), fruit yield (26.96 t ha-1 and 0.910 kg plant-1), total NPK uptake (13.76, 1.79 and 13.34 kg ha-1). Among soil properties maximum value of organic carbon (1.30%), macronutrient (NPK) content (441.73, 76.71 and 290.10 kg ha-1), DTPA extractable cations (3.12, 2.89, 7.50 and 2.76 ppm) were obtained in treatment T2. An experimental evaluation of different treatments leads to conclusion that treatment with 90% RDN, PGPR and liquid manures was best among all treatments and it had significant effects on plant as well as soil properties.

Limited Ecosystem Recovery from Simulated Chronic Nitrogen Deposition

The realization that anthropogenic nitrogen (N) deposition is causing significant environmental change in many ecosystems has led to lower emissions of reactive N and deposition rates in many regions. However, the impacts of N deposition on terrestrial ecosystems can be long lasting, with significant inertia in the return of the biota and biogeochemical processes to baseline levels. To better understand patterns of recovery and the factors that may contribute to slow or no responses following declines in N deposition, we followed plant species composition, microbial abundance, N cycling rates, soil pH, and pools of NO3 - and extractable cations in an impacted alpine ecosystem following cessation of 12-yr experiment increasing N deposition rates by 0, 20, 40, and 60 kg N·ha-1 ·yr-1 . Simulated N deposition had resulted in a tripling in the cover of the nitrophilic species Carex rupestris, while the dominant sedge Kobresia myosuroides had decreased by more than half at the highest N input level. In addition, nitrification rates were elevated, soil extractable magnesium (Mg2+ ) and pH decreased, and aluminum (Al3+ ) and manganese (Mn2+ ) were elevated at the highest N treatment inputs. Over the nine years following cessation of N additions to the impacted plots, only the cover of the nitrophilic C. rupestris showed any recovery to prior levels. Abundances of both bacteria and fungi were lower with N addition in both treatment and recovery plots. Rates of nitrification and pools of NO3 - remained elevated in the recovery plots, likely contributing to the lack of biotic response to the cessation of N inputs. In addition, nutrient base cations (Ca2+ and Mg2+ ) and soil pH remained depressed, and the toxic metal cations (Al3+ and Mn2+ ) remained elevated in recovery plots, also potentially influencing biotic recovery. These results emphasize the importance of considering long-term environmental impacts of N deposition associated with legacy effects, such as elevated N cycling and losses of base cations, in determining environmental standards such as the metrics used for critical loads.

Limited ecosystem recovery from simulated chronic nitrogen deposition.

The realization that anthropogenic nitrogen (N) deposition is causing significant environmental change in many ecosystems has led to lower emissions of reactive N and deposition rates in many regions. However, the impacts of N deposition on terrestrial ecosystems can be long lasting, with significant inertia in the return of the biota and biogeochemical processes to baseline levels. To better understand patterns of recovery and the factors that may contribute to slow or no responses following declines in N deposition, we followed plant species composition, microbial abundance, N cycling rates, soil pH, and pools of NO3- and extractable cations in an impacted alpine ecosystem following cessation of 12-yr experiment increasing N deposition rates by 0, 20, 40, and 60kg N·ha-1 ·yr-1 . Simulated N deposition had resulted in a tripling in the cover of the nitrophilic species Carex rupestris, while the dominant sedge Kobresia myosuroides had decreased by more than half at the highest N input level. In addition, nitrification rates were elevated, soil extractable magnesium (Mg2+ ) and pH decreased, and aluminum (Al3+ ) and manganese (Mn2+ ) were elevated at the highest N treatment inputs. Over the nine years following cessation of N additions to the impacted plots, only the cover of the nitrophilic C.rupestris showed any recovery to prior levels. Abundances of both bacteria and fungi were lower with N addition in both treatment and recovery plots. Rates of nitrification and pools of NO3- remained elevated in the recovery plots, likely contributing to the lack of biotic response to the cessation of N inputs. In addition, nutrient base cations (Ca2+ and Mg2+ ) and soil pH remained depressed, and the toxic metal cations (Al3+ and Mn2+ ) remained elevated in recovery plots, also potentially influencing biotic recovery. These results emphasize the importance of considering long-term environmental impacts of N deposition associated with legacy effects, such as elevated N cycling and losses of base cations, in determining environmental standards such as the metrics used for critical loads.

Phosphorus in Morgan Soil Test Extracts Measured By Molybdate Colorimetric and Inductively Coupled Plasma Spectroscopy Methods

ABSTRACTColorimetric P determination mainly reflects inorganic P, whereas inductively coupled plasma spectroscopy (ICP) measures all P in solution. We compared Morgan extractable P for ICP (MP-ICP) and colorimetry (MP-Color) using dairy farm field samples (0 to 20 cm) across northern New York (n = 250) and hayfield transect samples (0–15, 15–30, 45–50 cm; n = 164). Soil organic matter, pH, and extractable cations were also measured. Mean ratio of MP-ICP: MP-Color was 1.46 and differed significantly among Morgan P categories, ranging from 1.89 for low to 1.06 for very high. The numeric difference between MP-ICP and MP-Color ranged from 0 to 12.9 mg kg−1. Organic matter, Al, and pH jointly accounted for 55% of the variability between methods across samples. Fertilizer P recommendations differed based on the two methods, suggesting results from both methods should be reported, particularly in the responsive range.

Plant diversity is coupled with beta not alpha diversity of soil fungal communities following N enrichment in a semi-arid grassland

Soil fungi and plants are tightly linked in pathogenic, commensal, and mutualistic ways. These interactions play a critical role in terrestrial ecosystem decomposition, nutrient cycling, and maintenance of plant productivity and diversity. A comprehensive understanding whether this fundamental plant-fungi relationship persists in ecosystems with increased N input is, however, still lacking. In this study, we investigated the relationships between plant and soil fungal diversity in a 6-year multi-level nitrogen addition experiment in a semi-arid grassland in northern China, using Illumina Miseq sequencing of the ITS1 barcode region for fungal identification. We hypothesized that N-induced changes in plant communities would be positively associated with those in soil fungal communities, and that the corresponding changes in both communities can be explained by the direct functional associations between plant and soil fungal communities and their shared environmental drivers. Our results showed that N-induced changes in plant alpha diversity, i.e., Shannon diversity, showed no significant relationship with those in soil fungal alpha diversity. The lack in significance of the relationship was primarily due to their contrasting correlates with N-induced soil physicochemical variables (i.e., soil available P (AP), inorganic N (NH4+_N and NO3−_N) and organic C content), and weakened plant-fungi functional associations. In contrast to the lack of relationship between plant and soil alpha diversity, we did find a significant positive relationship between plant and fungal beta diversity (compositional dissimilarity between plots) under N enrichment. Our results reveal that the same soil physicochemical variables, including soil AP, inorganic N, moisture, pH, and associated extractable cations, correlated with compositional changes in plant and fungi following N enrichment. The strong coupling of plant and fungal beta diversity could largely be driven by their consistent responses to these shared edaphic factors. As such, our results suggest that information on N-induced changes in plant diversity can be used to predict beta, but not alpha diversity of soil fungal communities in semi-arid grassland ecosystems.

Andisols of Turkey: An example from the Cappadocian Volcanic Province

A number of studies have been conducted on the genesis of soils from volcanic deposits in semi- humid and humid climates. However, there has been little study of the mineralogical properties and genesis of soils from volcanic rocks in arid and semi-arid climates. This study was conducted to understand the genesis of soils from different volcanic parent materials, such as andesite, dacite, volcanic ash, basalt and ignimbrite, in the region east of the Erciyes stratovolcano in Central Anatolia. At least three soil profiles were selected from each parent material, and 17 soil profiles were described. Soil samples were also taken from each soil horizon for physical, chemical and mineralogical analyses. Soil profiles vary according to elevation and the types of derived-parent materials and are divided into 17 pedons and 15 horizons (2A, 2Bw, 2Bw1, 2C, A2, BC, Bw, Bw1, Bw2, Bw3, C, C1, C2, Cr, R). Soil acidity varied from slightly alkaline to slightly acidic in all soils. Organic matter contents were higher in the surface horizons and generally decreased with depth in all pedons. The extractable cation values of ammonium oxalate, pyrophosphate, dithionite-citrate and sodium pyrophosphate, as well as unhydrolyzed volcanic glass, allophone, imogolite, smectite and ferrihydrite contents of the soils, are variable based on the parent materials, pedons and elevations that are typical of the Cappadocian volcanogenic soils in Anatolia of Turkey. These soils can generally be described as alu-andic Andisols, due to their Alo+1/2Feo values and Alp/Alo ratios. The important factors affecting the formation and development of soils are climatic variations affecting horizon development and genesis, soil parent material diversities and leaching regimes originating from elevation differences.