Variation In Soil pH Research Articles

Preliminary assessment of the ecochemical condition of soils after fertilization of younger spruce Picea abies (L.) H. Karst. stands in the Beskid Slaski and Zywiecki Mts.

The experimental plots were located in the middle forest zone (900– 950 m) on two nappes of the flysch Carpathians: Magura (the Ujsoly Forest District) and Silesian (the Wisla Forest District) in the spruce stands of age class 21– 40 years. Serpentinite was introduced in the autumn of 2008 on all plots while other fertilizers (N, P, NP and NPK) in the spring of 2009. Based on the chemical composition of soil solutions collected in lysimeters placed at the depth of 20 cm in the autumn 2008 and the spring and autumn 2009, ecochemical parameters were calculated: acid neutralization capacity (ANC aq ) , alkalinity (ALK), the degree of soil acidity (Ma%), acidic cations (Ma), saturation of the exchangeable complex of the soil solid phase (Mb) with alkalis, saturation with alkalis (BS), molar relations Ca/Al, Mb/Al, BC/Al. After the winter, soil solutions became acidic, especially in the Wisla Forest District. The saturation of the studied soils demonstrates moderate flexibility of soils in the Wisla Forest District in relation to acid load, and high flexibility of the Ujsoly soils. The opposite trend was observed for the degree of acidity of soils. Acid neutraliza tion capacity and alkalinity of the waters showed significant variations in soil pH even in the case of small variations in the composition of the solution, if they were caused by the inflow of the anions of NO 3 - and SO 4 2- . After application of the fertilizers, an increase of Mg, Ca and Mb was noted in the soil solution, determined in the overlaying highly acidic organic horizons trough the ion-exchange buffering mechanism of highly protonated functional groups with high buffering capacity. Highly improved content of Mg in a soil, and in some cases – also the content of N, P and K, present potential improvement of forest growth capacity without the hazard of adverse side-effects of liming. Aluminum stress in the spruce is unlikely, while trees in the control plots in the Wisla Forest District may already be sensitive.

Effect of annual variation in soil pH on available soil nutrients in pear orchards

Soil pH is an important factor affecting the availability of soil nutrients that impact plant growth. Given the susceptibility of soil pH to excessive fertilization and the widespread use of manures, it is essential to examine the influence of soil pH on the distribution and availability of soil nutrients. We sampled and analyzed brown soils from pear orchards in thirteen towns in Wendeng county. Samples were obtained from areas along or between rows of trees at specified distances and depths. The results showed that the soil pH fluctuated from 4.06 to 6.59 in October 2008 and from 4.24 to 7.57 in April 2009. The quantity of soil samples with pH below 5.50 increased by 34.6%. Analysis of the soil pH for samples obtained along the rows of trees showed that the pH decreased as the depth increased (except for the range 5.5 to 6.0); soil pH in the samples obtained between the rows of trees demonstrated different trends. The average organic matter (O.M.) content as well as the N ( NH 4 + ) and available P, K, Cu, Zn, Fe, and Mn contents in the samples collected in October 2008 were higher than those observed in April 2009. Conversely, the values for other available nutrients were lower than those in the samples collected in April 2009. The available nutrients and organic matter (O.M.) content in different pH ranges varied. The soil pH was significantly or very significantly correlated with N ( NH 4 + and NO 3 - ), available K, Cu, Fe, and exchangeable Ca for the October 2008 samples, while a significant or very significant correlation existed between N ( NH 4 + ), available P, Zn, exchangeable Ca, and exchangeable Mg for the April 2009 samples. The correlations between soil pH and the amounts of available nutrients and organic matter (O.M.) along the rows of trees in September 2009 were nearly consistent with those between the rows.

Decreased N2O reduction by low soil pH causes high N2O emissions in a riparian ecosystem

Quantification of harmful nitrous oxide (N(2)O) emissions from soils is essential for mitigation measures. An important N(2)O producing and reducing process in soils is denitrification, which shows deceased rates at low pH. No clear relationship between N(2)O emissions and soil pH has yet been established because also the relative contribution of N(2)O as the denitrification end product decreases with pH. Our aim was to show the net effect of soil pH on N(2)O production and emission. Therefore, experiments were designed to investigate the effects of pH on NO(3)(-) reduction, N(2)O production and reduction and N(2) production in incubations with pH values set between 4 and 7. Furthermore, field measurements of soil pH and N(2)O emissions were carried out. In incubations, NO(3)(-) reduction and N(2) production rates increased with pH and net N(2)O production rate was highest at pH 5. N(2)O reduction to N(2) was halted until NO(3)(-) was depleted at low pH values, resulting in a built up of N(2)O. As a consequence, N(2)O:N(2) production ratio decreased exponentially with pH. N(2)O reduction appeared therefore more important than N(2)O production in explaining net N(2)O production rates. In the field, a negative exponential relationship for soil pH against N(2)O emissions was observed. Soil pH could therefore be used as a predictive tool for average N(2)O emissions in the studied ecosystem. The occurrence of low pH spots may explain N(2)O emission hotspot occurrence. Future studies should focus on the mechanism behind small scale soil pH variability and the effect of manipulating the pH of soils.

Soil bacterial diversity in the Arctic is not fundamentally different from that found in other biomes

The severe environmental stresses of the Arctic may have promoted unique soil bacterial communities compared with those found in lower latitude environments. Here, we present a comprehensive analysis of the biogeography of soil bacterial communities in the Arctic using a high resolution bar-coded pyrosequencing technique. We also compared arctic soils with soils from a wide range of more temperate biomes to characterize variability in soil bacterial communities across the globe. We show that arctic soil bacterial community composition and diversity are structured according to local variation in soil pH rather than geographical proximity to neighboring sites, suggesting that local environmental heterogeneity is far more important than dispersal limitation in determining community-level differences. Furthermore, bacterial community composition had similar levels of variability, richness and phylogenetic diversity within arctic soils as across soils from a wide range of lower latitudes, strongly suggesting a common diversity structure within soil bacterial communities around the globe. These results contrast with the well-established latitudinal gradients in animal and plant diversity, suggesting that the controls on bacterial community distributions are fundamentally different from those observed for macro-organisms and that our biome definitions are not useful for predicting variability in soil bacterial communities across the globe.

Overcoming the Confounding Effects of Salinity on Sodic Soil Research

The adverse effects of sodicity on plant growth are difficult to quantify using naturally occurring soils because of the confounding variation in other soil properties, particularly salinity, pH, organic matter, soil nutrients, mineralogy, and texture. We applied a method involving the equilibration of large soil volumes with solutions varying in sodium adsorption ratio (SAR), followed by excess salt removal with solutions of similar SAR but lower ionic strength. Application of this method to a calcareous nonsodic, nonsaline Vertosol from Narrabri, New South Wales, resulted in soils with exchangeable sodium percentage (ESP) values between 2% and 25% but with similar magnesium and potassium concentrations and constant electrical conductivity (∼2.7 dS/m). Soil pH and solution phosphorus concentrations automatically increased as the ESP of the soil rose, which is important to consider when addressing plant growth results. This method can successfully minimize the confounding of sodicity with other soil properties that so often plagues sodic soil research.

English

Reclamation efforts across Wyoming have been successful in reestablishing vegetative biomass, but restoration of a diverse vegetative community has proven difficult. We hypothesize that the lack of diverse plant species establishment is due, in part, to the homogenization of the soil environment occurring with disturbance and reclamation. Spatial heterogeneity of vegetation and soil characteristics using geospatial statistics has not been widely examined in wildland systems, particularly in relation to post-disturbance recovery of soils and vegetation. The purpose of this project was to quantify the spatial variability of key soil characteristics on a recently installed and reclaimed pipeline and adjacent undisturbed reference site in south central Wyoming. Soils (0-5 cm) were sampled on a grid design at a small spatial scale (10 - 1000 cm). Soils were analyzed for soil moisture, pH, electrical conductivity, and major microbial group abundance. In general, reclaimed soils support more biomass of vegetation and soil microbes than undisturbed soils. We found weak spatial dependence of most soil properties measured, and the response of the property to disturbance and reclamation varied by property. Spatial variability of soil pH, bacteria abundance, and AM fungi abundance appear to be most affected by soil disturbance and reclamation, but further investigation into the spatial patterns of soil and vegetation properties is warranted.

Variations in Yield, Quality, and Antioxidant Potential of Kalmegh (Andrographis paniculata Nees) with Soil Alkalinity and Season

The edaphoclimatic conditions that affect the yield and qualities of Andrographis paniculata Nees, (Kalmegh) were studied. Under seasonal and soil pH variations, andrographolide content ranged between 2.25–3.85% in aerial parts of the plant. Total phenolic content, antioxidant activity and reducing power were 20.3 mg g−1 GAE, 66.8% and 2.8 ASE mL−1. FRSA measured by DPPH showed an IC50 of 0.34 mg mL−1, EC50 of 14.7 mg mg−1 DPPH, and anti-radical power of 6.76. AOA in different assays expressed as IC50 ranged from 0.31 to 1.29 mg mL−1. The extract showed significant protective effect against Fenton's reaction on supercoiled pUC18 DNA.

Assessing past temperature and soil pH estimates from bacterial tetraether membrane lipids: Evidence from the recent lake sediments of Lochnagar, Scotland

Past variation in soil pH and air temperature can potentially be reconstructed from the relative abundance in sediments of branched glycerol dialkyl glycerol tetraethers (GDGTs), synthesized by anaerobic bacteria. Specifically, the cyclization of branched tetraethers (CBT) is believed to be a function of pH, whereas temperature can be estimated from a combination of the extent of both the CBT and methylation of branched tetraethers. Here we explore this potential by comparing a recent sedimentary GDGT profile from Lochnagar, Scotland, with reconstructed air temperature (statistically extrapolated from regional instrumental data sets) and diatom‐inferred lake water pH for the past ∼200 years. Branched glycerol dialkyl glycerol tetratether and diatom‐inferred pH generally agree throughout the core, supporting the use of cyclization of branched tetraethers to reconstruct pH. During the period of rapid industrial acidification (∼1860–1970 A.D.), changes in diatom‐inferred pH lag behind those inferred using branched tetraethers by between 10 and 50 years, possibly due to differing nonlinear responses to acid deposition within soil and lake water environments. However, branched‐GDGT‐derived temperatures are both lower than extrapolated mean annual air temperature estimates (by ∼5°C) and exhibit at least double the rate of reconstructed warming (∼2.5°C in 200 years). At Lochnagar, methylation and cyclization of branched tetraethers are closely correlated (r2 = 0.96) suggesting that in this setting the underlying controls over the two indices may not significantly differ. Therefore the validity of branched‐GDGT‐derived temperature is uncertain and further research is required to address the environmental controls over branched glycerol dialkyl glycerol tetratether synthesis and thus their value as palaeoclimate proxies.

A process-based model of N2O emission from a rice-winter wheat rotation agro-ecosystem: Structure, validation and sensitivity

In order to numerically simulate daily nitrous oxide (N2O) emission from a rice-winter wheat rotation cropping system, a process-based site model was developed (referred to as IAP-N-GAS) to track the movement and transformation of several forms of nitrogen in the agro-ecosystem, which is affected by climate, soil, crop growth and management practices. The simulation of daily N2O fluxes, along with key daily environmental variables, was validated with three-year observations conducted in East China. The validation demonstrated that the model simulated well daily solar radiation, soil temperature and moisture, and also captured the dynamics and magnitude of accumulated rice aboveground biomass and mineral nitrogen in the soil. The simulated daily N2O emissions over all three years investigated were generally in good agreement with field observations. Particularly well simulated were the peak N2O emissions induced by fertilizations, rainfall events or mid-season drainages. The model simulation also represented closely the inter-annual variation in N2O emission. These validations imply that the model has the capability to capture the general characteristics of N2O emission from a typical rice-wheat rotation agro-ecosystem. Sensitivity analyses revealed that the simulated N2O emission is most sensitive to the fertilizer application rate and the soil organic matter content, but it is much less sensitive to variations in soil pH and texture, temperature, precipitation and crop residue incorporation rate under local conditions.

Variations in soil properties and herbicide sorption coefficients with depth in relation to PRZM (pesticide root zone model) calculations

There are few experimental data available on how herbicide sorption coefficients change across small increments within soil profiles. Soil profiles were obtained from three landform elements in a strongly-eroded agricultural field and segmented into 2-cm intervals to 0.6 m depth in the knoll (eroded-upper slope), to 1.0 m depth in the toeslope (deposition zone) and to 1.6 m depth in the trough (eroded water-way). Soil samples were analyzed for soil organic carbon content (SOC) ( n = 154), soil pH ( n = 155), soil carbonate content ( n = 126), CEC ( n = 126), soil texture ( n = 32), bulk density ( n = 160), 2,4-D [2,4-( dichlorophenoxy) acetic acid] or glyphosate [ N-phosphonomethylglycine] sorption by soil (Kd) ( n = 90), and 2,4-D or glyphosate sorption per unit soil organic carbon (Koc) ( n = 90). Considering all soil profiles, 2,4-D Kd values ranged from 0.12 to 2.61 L kg − 1 and were most strongly influenced by variations in SOC. In contrast, glyphosate Kd values ranged from 19 to 547 L kg − 1 and were predominantly controlled by variations in soil pH and clay content. Two hundred and fifty-two PRZM (pesticide root zone model) version 3.12.2 simulations were also performed. PRZM predicted that glyphosate would be immobile in soils even under an extreme rainfall scenario of 384 mm at one day after herbicide application. In contrast, for 2,4-D, PRZM predicted that up to 6% of the applied herbicide would move to a 15 cm depth under an actual rainfall scenario. PRZM output was particularly sensitive to input values of Kd, relative to input values of soil properties. The greatest change to PRZM outputs occurred when Kd values of toeslope profiles, ranging from 0.16 to 1.77 L kg − 1 , were replaced by those measured in knoll profiles, ranging from 0.12 to 0.50 L kg − 1 , when the amount of 2,4-D leached to a 15 cm depth increased by 29,081% (from 0.09 to 26.17 g ha − 1 ) under an actual rainfall scenario. We conclude that, when pesticide fate models such as PRZM are being used in policy analyses at larger-scales, data on Kd values in different landform elements and at the soil horizon level could be important for strengthening pesticide leaching predictions.

Monitoring the Variability of Nitrogen and Cadmium Concentrations in Soils and Irrigation Water in the Almyros Area of Central Greece

The main purpose of this investigation was the monitoring of nitrogen (N) and cadmium (Cd) levels in soils and irrigation water samples in an intensively cultivated area in central Greece. From 2005 to 2007, soil as well as irrigation water samples were collected two periods a year (March and October) at the same sampling sites in the Almyros area. Nitrogen was measured in three forms (as nitrate, nitrite, and ammonium) using the anion chromatography method. Available and total Cd concentrations were measured using atomic absorption spectroscopy, after extraction with diethylenetriaminepentaacetic acid (DTPA) and aqua regia extraction solutions, respectively. The nitrate, nitrite, ammonium, and Cd concentrations were always less than the corresponding water standards. Cadmium concentration (total and DTPA extractable) in soil samples was high in the sites where phosphate fertilizers had been intensively used for the crops. Seasonal variation was found in all parameters measured between the autumn and spring of each year. No temporal variation was found, as there was no statistical difference in nitrate, nitrite, and ammonium or in Cd concentration among the years of the study. A spatial variation was observed in all the parameters and was illustrated by the respective thematic maps. Thematic maps of predictions of the measured variables, as well as for pH and electrical conductivity, were generated using geostatistics as a helpful tool in sustainable soil management of the study area. The spatial variability of available Cd was found to follow the variability of soil pH, as highly available Cd concentration was observed in highly acid soils. Significant correlations among nitrate, nitrite, ammonium, available and total Cd, and soil physicochemical parameters were obtained and discussed.

Spatial variation of soil and plant properties and its effects on the statistical design of a field experiment

The standard procedure in field experimentation is to use a randomized complete block (RCB) design, striving for the most homogeneous conditions as possible among plots in the same block. However, geostatistical concepts dictate that a spatial dependence exists for observations of a particular property, where closely spaced are more similar than those taken at a greater distance. The present study was conducted on an 18 ha lucerne (Medicago sativa) stand in which a 113 m X 145 m experimental area was demarcated. To determine spatial characteristics of soil and plant properties, 48 sampling points were selected using a 20 m square grid with an additional 75 points on a 2.5 m grid at five random node points. A RCB design trial was superimposed on the geostatistical grid design and consisted of seven pseudo (i.e. non-existent) treatments, replicated four times. Soil and plant samples were taken in June 2001 at all sampling points and plots and analyzed for various properties, including green biomass yield. Analysis of variance of the RCB design revealed statistically non-significant differences among the pseudo treatments, as expected, for various soil and plant properties, including yield. Although large yield differences (2.1 – 5.3 t ha- 1) were observed, the conclusion could be made that the experimental field was homogeneous enough to lay out a RCB design experiment. However, it was found that the estimate map of soil pH(H2O) indicated a spatial dependence. The question was posed that if spatial variation in soil pH(H2O) had been considered, would it have had any effect on the results of this field experiment, for example, in terms of yield? Scrutiny of the latter variability revealed that the standard RCB designs did not provide homogeneous blocks with respect to soil variability. The redesign of the experiment where all plots were randomly allocated to treatments and replications, led to significant differences obtained for plant and soil properties as a function of the pseudo treatments. Analysis of co-variance was then applied to eliminate variability between plots and the resultant pseudo treatments showed no significant differences. From this study it became evident that spatial variability of soil and plant properties can jeopardize the results of a standard RCB designed field experiment and should be taken cognizance of.

Changes in soil fertility parameters and the environmental effects in a rapidly developing region of China

An extensive knowledge of the temporal variability of soil fertility parameters and how this variation affects the environment is imperative to a wide range of disciplines within agricultural science for optimal crop production and ecosystem preservation. This paper examines the temporal variability of soil pH, organic matter (OM), cation exchange capacity (CEC), total nitrogen (TN), total phosphorus (TP), available phosphorus (P Av), and available potassium (K Av) on Cambosols (Entisols) ( n = 179) and Anthrosols (Inceptisols) ( n = 95) in Zhangjiagang County, China from 1980 to 2004. Nutrient input was monitored from 1983 to 2004. Annual N fertilizer rates were significantly different during three periods (1983–1989, 1989–1999, 1999–2004), where annual rates increased significantly after 1989 and then decreased after 1999. Annual P fertilizer rates were significantly different during two periods (1983–1993, 1993–2004) where annual rates increased after 1993. No change was found in K fertilizer rates. Soil pH marginally increased by 0.14 units in Cambosols, but significantly decreased by 1.02 units in Anthrosols. OM, CEC, and TN increased in both soil orders an average of 2.15 g kg −1, 1.6 cmol kg −1, and 0.21 g kg −1, respectively. TP decreased in Anthrosols by 70 mg kg −1, P Av increased in Cambosols by 4.83 mg kg −1, and K Av decreased in Cambosols by 15 mg kg −1. Fertilizer input rates are causing nutrient imbalances, contributing to acidification in Anthrosols, and decreasing C/N ratios. Nutrient loading of N and deficiency of K is also a potential problem in the area. Efforts should be made to readjust soil nutrient inputs to reach an optimal, sustainable level.

Factors that Influence the Transport of Bacillus cereus Spores through Sand

The goal of this study is to clarify the surface-chemical and microphysical variables that influence bacterial spore transport through soil, thereby defining the factors that may affect spore transport velocity. Bacillus cereus spores were continuously monitored in a soil column under saturated conditions with experimental variations in soil grain size (0.359 and 0.718 mm), pH (7.2 and 8.5), and water flow rate (1.3 and 3.0 mL/min). Increasing soil grain size, flow rate, and pH resulted in enhanced spore movement. Spore transport increased 82% when soil grain size was doubled. An increase in effluent flow rate from 1.3 to 3.0 mL/min increased spore movement by 71%. An increase in pH increased spore transport by 53%. The increase in hydrodynamic forces resulting from the larger grain size soil and higher flow rate functioned to overcome the hydrophobic nature of the spore’s coat, and the interparticle bonding forces between the spore and soil particles.

On the biogeography of seed mass in Germany – distribution patterns and environmental correlates

With environmental factors being spatially structured, plant traits that are related to these factors should exhibit a corresponding spatial pattern. We analyzed the distribution pattern of seed mass in Germany. We calculated the median seed mass for 10′ longitude by 6′ latitude grid cells across Germany using the trait databases BIOLFLOR and the plant distribution database FLORKART. To explain these distribution patterns of median seed mass, we applied multiple regression analyses on twelve selected environmental variables, accounting for spatial autocorrelation. To deal with collinearities of the predictors, we used hierarchical partitioning to analyze the independent and joint explanatory power of the environmental variables. To test whether statistical relationships are due to hidden correlations between seed mass and plant growth form, we conducted seperate analyses for annual, perennial herbs, shrubs and trees. Low median seed mass was found in the lowlands and river valleys whereas high median seed mass was typical for the rich loess regions and the calcareous mountain ranges. Seed mass exhibited a strong positive correlation with soil pH (62% of variance explained) and a negative correlation with soil moisture (25%). Light was less important as a predictor of seed mass. Within the growth forms we observed similar distribution and correlation patterns pointing to a direct link between seed mass and the environmental variables soil pH and moisture. We argue that this striking relationship with soil pH is caused by the high stress from competition on fertile calcareous sites. The negative moisture effect may be due to drought stress. Both relationships are particulary interesting for the prediction of ecosystem responses to climate and land use changes.

Colonisation by arbuscular mycorrhizal and fine endophytic fungi in four woodland grasses – variation in relation to pH and aluminium

Acidic soils are harsh environments for plants. One of the major problems is the potential toxicity of aluminium (Al) and hydrogen ions at a pH below 5; another is the shortage of nutrients usually accompanying soil acidity. The aim of this study was to elucidate the relationship between arbuscular mycorrhizal (AM) colonisation and soil acidity (measured by pH and Al concentration) in order to evaluate the possibility that AM fungi facilitate the existence of plants on acidic soils. We sampled tussocks of four grass species, Elymus caninus, Poa nemoralis, Deschampsia cespitosa and Deschampsia flexuosa, together with samples of the surrounding soil, in oak forests of varying soil pH in southern Sweden. We determined pH, easily reacting Al (Al r), extractable Al (Al BaCl2) and phosphate in the soil samples, analysed the shoots for Al and phosphorous and quantified the degree of AM and fine endophyte (FE) colonisation in the roots. E. caninus was found on the least acidic soils and had the highest AM colonisation of all the species studied, while D. flexuosa, which was found on the most acidic soils, had the lowest AM colonisation. P. nemoralis and D. cespitosa were intermediate with respect to pH and AM colonisation. The colonisation of AM fungi exceeded FE colonisation for E. caninus and P. nemoralis, while the opposite was true for the two Deschampsia species. Our results indicated a negative relationship between Al r and the degree of AM colonisation at the within-species level. The low colonisation of AM fungi on acidic soils may to some extent be explained by a sensitivity of AM fungi to Al r: this parameter showed a stronger negative association with AM colonisation than did pH and Al BaCl2. We hypothesize that Al toxicity is a critical factor for plant nutrition in forest soils through the impact on symbiotic fungi.

Zinc Fractionation in Contaminated Soils by Sequential and Single Extractions: Influence of Soil Properties and Zinc Content

We studied the fractionation of zinc (Zn) in 49 contaminated soils as influenced by Zn content and soil properties using a seven-step sequential extraction procedure (F1: NH4NO3; F2: NH4-acetate, pH 6; F3: NH3OHCl, pH 6; F4: NH4-EDTA, pH 4.6; F5: NH4-oxalate, pH 3; F6: NH4-oxalate/ascorbic acid, pH 3; F7: residual). The soils had developed from different geologic materials and covered a wide range in soil pH (4.0-7.3), organic C content (9.3-102 g kg(-1)), and clay content (38-451 g kg(-1)). Input of aqueous Zn with runoff water from electricity towers during 26 to 74 yr resulted in total soil Zn contents of 3.8 to 460 mmol kg(-1). In acidic soils (n = 24; pH <6.0), Zn was mainly found in the mobile fraction (F1) and the last two fractions (F6 and F7). In neutral soils (n = 25; pH > or =6.0), most Zn was extracted in the mobilizable fraction (F2) and the intermediate fractions (F4 and F5). The extractability of Zn increased with increasing Zn contamination of the soils. The sum of mobile (F1) and mobilizable (F2) Zn was independent of soil pH, the ratio of Zn in F1 over F1+F2 plotted against soil pH, exhibited the typical shape of a pH sorption edge and markedly increased from pH 6 to pH 5, reflecting the increasing lability of mobilizable Zn with decreasing soil pH. In conclusion, the extractability of Zn from soils contaminated with aqueous Zn after decades of aging under field conditions systematically varied with soil pH and Zn content. The same trends are expected to apply to aqueous Zn released from decomposing Zn-bearing contaminants, such as sewage sludge or smelter slag. The systematic trends in Zn fractionation with varying soil pH and Zn content indicate the paramount effect of these two factors on molecular scale Zn speciation. Further research is required to characterize the link between the fractionation and speciation of Zn and to determine how Zn loading and soil physicochemical properties affect Zn speciation in soils.

No short-term change in soil properties following four-fold litter addition in a Costa Rican rain forest

We experimentally manipulated forest floor litter to investigate the influence of litter quality and quantity on soil properties over the short-term (weeks to months) in a wet tropical forest in NE Costa Rica. The study included old growth forest on high fertility soils, old growth forest on low fertility soils, and secondary forest on intermediate fertility soils. Forest floor litter was removed from a 16 m 2 area and added to an adjacent 4 m 2 area in March 2003, resulting in a one to four-fold increase in the annual litter input to the forest floor. We created three addition, three removal and three control plots per forest type. We measured treatment effects on variation in soil moisture, temperature, pH, and Bray-1 P (plant available) over a 5-month period that captured the dry-wet season transition. Litter manipulation had no effect on any of the soil properties measured during the 5-month study period. Significant variability through time and a similar temporal pattern across the three forest stands suggest that climatic variability is driving short-term patterns in these soil properties rather than seasonal inputs of litter. In general, soils were warmer, drier and more basic with higher available P during dry season months. Even in wet tropical forests, small variability in climate can play an important role in soil dynamics over periods of weeks to months. Although litter manipulation did not influence soil properties over the 5-month study period, a longer lag may exist between the timing of litter inputs and the influence of that litter on soil properties, especially plant available P.

Effects of ISPOLIN Fertilizer on Uptake of Macro- and Trace Elements by Wheat Grown in Two Different Soils

ABSTRACT Variations in concentrations of 24 elements in soils with loam and sandy loam texture and in Triticum aestivum wheat seedlings grown in the soils under greenhouse conditions were studied. Initial soils differed significantly in concentrations of 20 elements. Elemental composition of wheat seedlings depended on the soil where the plants were grown. An application of ISPOLIN (fertilizer enriched with potassium) resulted in variations in soil pH, plant biomass, and concentrations of several elements both in soils and in plants. An excess of bioavailable potassium (K) in soil led to significant increase of K and deficiency of calcium (Ca) and magnesium (Mg) in all parts of T. aestivum. Concentrations of many other elements in the plants also changed. The effects of soil fertilization on plant biomass, leaf chlorophyll, and plant element concentrations were soil-dependent. Depending on the ratio of K/Mg in the soils, there was either an increase of plant yield and chlorophyll content or no effect at all.

Controls over leaf and litter calcium concentrations among temperate trees

Four-fold variation in leaf-litter Ca concentration among 14 tree species growing in a common garden in central Poland was linked to variation in soil pH, exchangeable Ca, soil base saturation, forest floor turnover rates, and earthworm abundance. Given the potential importance of tissue Ca to biogeochemical processes, in this study we investigated potential controls on leaf Ca concentrations using studies of both laboratory seedlings and 30-year-old trees in the field. We first assessed whether species differences in Ca concentration of green leaves and leaf litter were due to differences in Ca uptake, plant growth, or Ca translocation to different organs, by measuring seedlings of 6 of the 14 species grown under controlled conditions of varying Ca supply. We also investigated whether trees species with high Ca concentrations in green leaves and leaf litter access soil Ca to a greater extent than low-Ca species by growing more fine roots in high-Ca soil horizons. Root distribution in the field was determined in all 14 tree species by profile wall mapping and soil sampling of excavated pits. There was no correlation between horizon root count density (number of roots m−2) and exchangeable soil Ca, nor was there a correlation of stand-level leaf litter Ca with density of roots 45–100 cm deep in the soil, suggesting that a deeper root distribution does not result in greater Ca acquisition among these species. Variation among species in leaf Ca concentration of greenhouse seedlings was positively correlated with leaf Ca concentrations of mature trees, indicating that the same ranking in leaf Ca among species existed under controlled Ca supply. Species also differed in seedling growth response to Ca supply. Tilia, the species with the highest leaf Ca in the field, generated only 10% as much biomass and height at low relative to high Ca supply, whereas the other species exhibited no significant differences. Species exhibited differences in (i) partitioning of whole plant Ca and biomass to leaf, stem and root organs and (ii) the pattern of such partitioning between high and low Ca treatments. Our data support the hypothesis that although soil Ca supply can contribute to variation among trees in leaf and litter Ca concentration, innate physiological differences among species also can be a major cause for species variation.