Acid Sandy Soils Research Articles

Effect of biochar origin and soil pH on greenhouse gas emissions from sandy and clay soils

Emissions of greenhouse gases (GHGs), such as carbon dioxide (CO2) and nitrous oxide (N2O) have great impact on global warming and atmospheric chemistry. Biochar addition is a potential option for reducing GHGs emissions through carbon (C) sequestration and N2O mitigation. However, the influences of biochar on C and nitrogen (N) transformations in soil are still unclear, resulting in a poor understanding of the mechanisms of N2O mitigation effects of biochar. Here we carried out two soil incubation experiments to investigate the influence of two common biochars addition (corn cob and olive pulp) with ammonium sulfate on CO2 and N2O emissions from two contrasting soil types (acidic sandy and alkaline clay soil). Furthermore, four extracellular enzymes activities that related to C and N cycling, i.e. cellobiohydrolase, chitinase, xylanase and β-glucosidase, were analyzed to gain insights into the underlying mechanisms of biochar’s effects on CO2 and N2O evolutions. Contrasting effects of two biochars on CO2 and N2O emissions were observed in the two different soils. The corn biochar addition had no significant effect on CO2 and N2O emissions in the alkaline clay soil, but significantly decreased CO2 emissions by 11.8% and N2O emissions by 26.9% in the acidic sandy soil compared to N-fertilizer only treatment. In contrast, olive biochar addition showed no significant effect on CO2 emissions but decreased N2O emissions by 34.3% in the alkaline clay soil, while in the acidic sandy soil addition of olive biochar triggered about a twofold higher maximum CO2 emission rate and decreased N2O emissions by 68.4%. Up to 50–130% higher specific CO2 emissions (per unit of C-related enzyme activity: cellobiohydrolase, chitinases and β-glucosidase) were observed after addition of olive biochar compared to corn biochar addition in the acidic sandy soil. We concluded that biochar’s effects on N2O and CO2 emissions are more pronounced in acidic soils. Alkaline biochar’s N2O mitigation potential in acidic soils seems to be dependent on soil NO3− content as drastically higher N2O emissions were measured in early phase of the experiment (where soil NO3− was high) and significantly lower N2O fluxes were obtained in later phases (with lower soil NO3− content).

Root Ideotype Influences Nitrogen Transport and Assimilation in Maize.

Maize (Zea mays, L.) yield is strongly influenced by external nitrogen inputs and their availability in the soil solution. Overuse of nitrogen-fertilizers can have detrimental ecological consequences through increased nitrogen pollution of water and the release of the potent greenhouse gas, nitrous oxide. To improve yield and overall nitrogen use efficiency (NUE), a deeper understanding of nitrogen uptake and utilization is required. This study examines the performance of two contrasting maize inbred lines, B73 and F44. F44 was selected in Florida on predominantly sandy acidic soils subject to nitrate leaching while B73 was selected in Iowa on rich mollisol soils. Transcriptional, enzymatic and nitrogen transport analytical tools were used to identify differences in their N absorption and utilization capabilities. Our results show that B73 and F44 differ significantly in their genetic, enzymatic, and biochemical root nitrogen transport and assimilatory pathways. The phenotypes show a strong genetic relationship linked to nitrogen form, where B73 showed a greater capacity for ammonium transport and assimilation whereas F44 preferred nitrate. The contrasting phenotypes are typified by differences in root system architecture (RSA) developed in the presence of both nitrate and ammonium. F44 crown roots were longer, had a higher surface area and volume with a greater lateral root number and density than B73. In contrast, B73 roots (primary, seminal, and crown) were more abundant but lacked the defining features of the F44 crown roots. An F1 hybrid between B73 and F44 mirrored the B73 nitrogen specificity and root architecture phenotypes, indicating complete dominance of the B73 inbred. This study highlights the important link between RSA and nitrogen management and why both variables need to be tested together when defining NUE improvements in any selection program.

Sewage sludge biochars management—Ecotoxicity, mobility of heavy metals, and soil microbial biomass

Production of biochar from sewage sludge may be a promising solution for sewage sludge management and improvement of soil properties, including carbon dioxide sequestration. The aim of the present study was to compare the effects of biochars derived from different sewage sludges on soil physicochemical and biological properties, ecotoxicity, and plant yield. Three biochars (produced at a temperature of 300 °C) were applied into sandy acid soil in doses of 0.5, 1, and 2% (w/w). Depending on the type and dose, the application of sewage sludge biochars into the soil caused diverse effects on the parameters of soil biological activity (microbial biomass [Cmic], soil respiration, and value of metabolic quotient). No correlation between the applied dose of biochars and inhibition of Vibrio fischeri luminescence was observed. The factor with a stronger impact on the activity of V. fischeri was the type of biochar. The use of the OSTRACODTOXKIT F test (MicroBioTests) showed that the addition of sewage sludge biochar (regardless of its dose) reduced the soil toxicity to Heterocypris incongruens compared with the control soil. A significant increase of Poa pratensis L. biomass was obtained in soils with 1 and 2% additions of each of the biochars. The addition of biochars in doses of 1 and 2% to the soil had greater effect on the content of mobile forms of Cu, Pb, and Cd than the 0.5% dose compared with the control. Environ Toxicol Chem 2018;37:1197-1207. © 2017 SETAC.

Determination of EC50Values for Cu, Zn, and Cr on Microorganisms Activity in a Mediterranean Sandy Soil

AbstractEcotoxicity of three potentially toxic metals (PTM) (Cu, Zn, and Cr) in a slightly acidic sandy soil is tested using the soil respiration test (OECD‐217) in order to determine EC50values for the carbon transformation activity of microorganisms. Addition of an organic amendment ofPopulusleaves is also crossed with metal spiking in order to investigate possible interaction with metal toxicity. Soil respiration is measured at day 1 and 28 after the soil spiking with the PTM to assess short‐term effects on soil microbial activity. Of the three metals tested, Cu shows the highest toxicity at the longest exposure times (day 28) and Zn shows a strong inhibitory effect in the short‐term (day 1), even though later toxicity diminish significantly. Cr is the least toxic studied PTM. Organic amendment outweighs any adverse effects of these metals, increasing soil respiration, even in the treatments with high doses of metals.

The interaction of high copper and zinc doses in acid soil changes the physiological state and development of the root system in young grapevines (Vitis vinifera)

Old vineyards may present high copper (Cu) content in the soil due to the frequent application of Bordeaux fungicide to control leaf fungal diseases. Thus, many wine makers replace copper fungicides by those made of zinc (Zn) and it leads to the accumulation of these two elements in vineyard soils, fact that may potentiate the occurrence of physiological disorders and morphological changes in the plant root system. The aim of the current study was to assess the effects of high Cu and Zn contents in a sandy acid soil on the physiological state and development of the root system in young grapevines. The soil was taken from a vineyard from Southern Brazil, and then it was sieved and had its acidity and P and K contents corrected. Next, the soil was subjected to the application of 0 and 120mg Cu kg−1; each one of these doses was added with 0, 120 and 240mg Zn kg−1, thus totaling six treatments. After the treatments were added to the soil samples, 2.4kg of soil was stored in rizobox-type containers. One young grapevine plant was transplanted to each box. The transplanted plants were cultivated for 60 days in greenhouse. The accumulation of root and shoot dry matter was set after the experimental period, as well as the Cu and Zn contents in the roots and shoot, the root system morphology, the chlorophyll a fluorescence, the photosynthetic pigments, the gas exchanges and the superoxide dismutase enzyme activity (SOD). Young grapevines presented mechanisms to tolerate high Cu and Zn concentrations in the soil, mainly through the retention of such metals in their roots to diminish translocation to the shoot. However, the highest Cu and Zn doses led to grapevine plant growth decrease, to gas exchange alterations and to photochemical efficiency reduction associated with photosynthetic pigment decrease and to non-photochemical energy dissipation increase. Moreover, the SOD activity was greater in intermediate Zn doses, thus indicating antioxidant system activation. Thus, the combination between high Cu and Zn concentrations in vineyard soils will enable minimizing the toxic effects of these metals to young grapevines cultivated in these soils.

Assessment of the Environmental Impact of Yeast Waste Application to Soil: An Integrated Approach

The yeast production industry (e.g. distillery, brewing, baking industries) has been growing globally over the last years generating a large amount of sub-products rich in organic matter that could be used as soil improvers or organic fertilizers. A set of laboratory experiments were performed to investigate the impact of yeast waste application to an acidic sandy soil on potential nutrient leaching and gaseous emissions. Experimental treatments were: surface application of yeast (CMSs) and decanted-yeast (CMSds), surface application of yeast (CMSm) and decanted-yeast (CMSdm) followed by incorporation in the 0–5 cm soil layer, surface application of ammonium nitrate (AN) and unfertilized soil (CTR). A leaching experiment (73-day period) with six irrigation events every 2 weeks was performed (6 treatments × 4 replicates) to assess N and P losses. Two parallel incubations (6 treatments × 3 replicates) were simultaneously performed to measure GHG emissions (CO2, N2O, CH4) and to assess the N mineralization in each treatment. Results showed that yeast application increased initial NH4+ concentration in leachates and soil relative to unfertilized soil and NO3− concentrations increased afterwards. Furthermore, yeast waste led to a significantly increase of N2O and CO2 in the first days of incubation. Gaseous emissions in AN treatment were very similar to unfertilized soil even if a small increase of N2O was also observed. CH4 emissions were insignificant in all treatments during the whole experiment. It is still to refer that the global warming potential of yeast and AN treatments were 6× and 2× times higher than control, respectively. Our results obtained in an acidic sandy soil allow concluding that yeast waste can be applied to soil as organic fertilizer since it provide not only nitrogen and potassium to plants but also contribute to increase soil organic matter content. Nevertheless, the potential nitrate leaching and increase of GHG emissions induced by yeast application to soil have to be carefully monitored to avoid environmental problems. Similar studies using different soil types as well as field experiments are still needed to confirm our conclusions.

Agronomic benefits of biochar as a soil amendment after its use as waste water filtration medium.

In many water-scarce countries, waste water is used for irrigation which poses a health risk to farmers and consumers. At the same time, it delivers nutrients to the farming systems. In this study, we tested the hypotheses that biochar can be used as a filter medium for waste water treatment to reduce pathogen loads. At the same time, the biochar is becoming enriched with nutrients and therefore can act as a fertilizer for soil amendment. We used biochar as a filter medium for the filtration of raw waste water and compared the agronomic effects of this "filterchar" (FC) and the untreated biochar (BC) in a greenhouse pot trial on spring wheat biomass production on an acidic sandy soil from Niger. The biochar filter showed the same removal of pathogens as a common sand filter (1.4 log units on average). We did not observe a nutrient accumulation in FC compared to untreated BC. Instead, P, Mg and K were reduced during filtration while N content remained unchanged. Nevertheless, higher biomass (Triticum L. Spp.) production in BC (+72%) and FC (+37%) treatments (20tha-1), compared with the unamended control, were found. There were no significant differences in aboveground biomass production between BC and FC. Soil available P content was increased by BC (+106%) and FC (+52%) application. Besides, mineral nitrogen content was reduced in BC treated soil and to a lesser extent when FC was used. This may be explained by reduced sorption affinity for mineral nitrogen compounds on FC surfaces. Although the nutrients provided by FC decreased, due to leaching in the filter, it still yielded higher biomass than the unamended control.

English

Cowpea is a major food legume crop in the Sahel with tolerance to drought and to the nutrients-leached acid sandy soils of this region. However, the existing cowpea varieties grown by farmers are low yielding and pest sensitive which make them unsuitable to satisfy farmer’s needs. The objective of this study was to identify high-yielding cowpea varieties which are well adapted to the Sahelian ecosystem. Eight dual-purpose cowpea varieties from various sources were tested with and without insects control in Niger during two cropping seasons (2005 and 2007). In 2005, a relatively wet year, KVX 745-11-P and four other varieties (ISV 20, ISV 40, ISV 128 and IT98D-1399) gave highest grain yields ranging from 1220 to 1521 kg ha-1. In the dry year (2007), the highest grain yield was recorded with ISV 128. There were also significant differences in forage yield between varieties in both the wet and dry year. Application of insecticide increased cowpea grain yields significantly. Cowpea produced without insect control (spray) resulted in high grain yields losses and increased cowpea fodder yields in both years. KVX 745-11-P was the most sensitive variety to insects whereas IT98D 1399 seemed to be relatively the most insect tolerant variety. There were no significant differences between varieties in most forage quality parameters. These results provide the possibility of a potential extension of dual-cowpea varieties for improved food security in the Sahel. Keywords: Dual purpose cowpea, grain yield, fodder quality, sahel

Regional analysis of groundwater phosphate concentrations under acidic sandy soils: Edaphic factors and water table strongly mediate the soil P-groundwater P relation

Historic long-term P application to sandy soils in NW-Europe has resulted in abundant sorption, saturation and eventually leaching of P from soil to the groundwater. Although many studies recognize the control of site-specific factors like soil texture and phosphate saturation degree (PSD), the regional-scaled relevance of effects exerted by single factors controlling P leaching is unclear. Very large observational datasets of soil and groundwater P content are furthermore required to reveal indirect controls of soil traits through mediating soil variables. We explored co-variation of phreatic groundwater orthophosphate (o-P) concentration and soil factors in sandy soils in Flanders, Belgium. Correlation analyses were complemented with an exploratory model derived using ‘path analysis’. Data of oxalate-extractable Al, Fe, P and pHKCl, phosphate sorption capacity (PSC) and PSD in three depth layers (0–30, 30–60, 60–90 cm), topsoil SOC, % clay and groundwater depth (fluctuation) were interpolated to predict soil properties on exact locations of a very extensive net of groundwater monitoring wells. The mean PSD was only poorly correlated to groundwater o-P concentration, indicating the overriding control of other factors in the transport of P to the groundwater. A significant (P < 0.01) positive non-linear relationship was found between groundwater o-P concentrations and pHKCl for all depth layers. Likewise, lower SOC% (P < 0.01) and shallower groundwater level (MHL or MLL) corresponded (P < 0.01) with higher o-P concentrations. Groundwater o-P unexpectedly correlated positively to clay% and path analysis indicated this to be an indirect effect of the groundwater level. Path analysis furthermore indicated an important indirect control of pH on groundwater o-P concentrations and a considerable direct effect of Pox, 0-90, Alox, 0-90 and MHL. The fact that groundwater o-P concentration was stronger controlled by soil pH and groundwater table depth than by PSD indicates the likely oversimplification of the latter index to measure the long-term potential risk of P leaching. Accounting for controls on leaching not included in PSD via an alternative index, however, seems problematic as in Flanders for example groundwater o-P turned out to be higher in finer textured soils or soils with higher pedogenic Fe content, probably because of their lower pedogenic Al content and higher soil pH. Path analysis of extensive soil and groundwater datasets seems a viable way to identify prime local determinants of soil P leaching and could be further on used for ‘ground-truthing’ more complex P-migration simulation models.

Copper Accumulation and Availability in Sandy, Acid, Vineyard Soils

ABSTRACTThe use of copper (Cu)-based fungicides to control diseases in vineyards can cause excessive Cu accumulation in soils. Greater Cu availability is expected in acid sandy soils with low organic matter (OM), where the risk of toxicity to plants and environment contamination is high. This study aimed to study the evolution of Cu in acid, sandy soils planted with grapevines for a period of time between 2 and 32 years. Two studies were carried out in South Brazil: in the first study, soil samples, from 19 vineyards were collected and analyzed in the first 0.2 m depth-layer for the total and available Cu. In the second study, 3 soils were selected among the previous 19 according to the age of vineyard (5, 11, and 30 year-old), and their 0.60 m-depth profile was analyzed for 5 fractions of Cu (soluble, exchangeable, mineral, organic, and residual). All the soils were classified as Ultisols. The vineyards with more than 25 years under cultivation had a mean total Cu concentration of 90 mg kg−1 in the 0–0.10 m layer. Approximately 80% of it was potentially available to plants. The greatest total and available Cu were found in the soil surface layers (0.2 m depth), where up to 75% of the total Cu is adsorbed in clay minerals and only 20% is complexed in the OM.

Tolerance and translocation of heavy metals in young grapevine (Vitis vinifera) grown in sandy acidic soil with interaction of high doses of copper and zinc

Vineyard soils may have high levels of copper due to frequent applications of Bordeaux mixture for the control of fungal diseases. Therefore, many winegrowers have used zinc-based fungicides instead of copper-based fungicides, resulting in high levels of Cu and Zn in vineyard soils. The aim of the study was to evaluate the tolerance of young grapevines grown in soil with interaction of high contents of Cu and Zn, and the translocation of these heavy metals from roots to shoots. We collected soil of a natural field of Rio Grande do Sul, the southernmost state of Brazil. Soil treatments were addition of 0, 30, and 60mg Cu kg−1, and addition of 0, 15, 30, 60, 120, and 180mg Zn kg−1 for each copper dose. A seedling of grapevine per pot was grown for 60days. After that, we measured root and shoot dry matter, Cu and Zn content in roots and shoots, chlorophyll a fluorescence, photosynthetic pigments, and peroxidase and superoxide dismutase activity. Young grapevines showed tolerance mechanisms to high concentrations of Cu and Zn by retaining these metals in the roots, decreasing translocation to the shoots. However, at the highest doses of Cu and Zn, we observed decrease in plant growth and in photochemical efficiency associated with the decrease in photosynthetic pigment content. Furthermore, the activity of antioxidant enzymes increased in intermediate doses of Zn, which indicates activation of the antioxidant system. However, the stress condition in treatments with high levels of Cu and Zn was not reversed.

Influence of red mud on soil microbial communities: Application and comprehensive evaluation of the Biolog EcoPlate approach as a tool in soil microbiological studies

Red mud can be applied as soil ameliorant to acidic, sandy and micronutrient deficient soils. There are still knowledge gaps regarding the effects of red mud on the soil microbial community. The Biolog EcoPlate technique is a promising tool for community level physiological profiling. This study presents a detailed evaluation of Biolog EcoPlate data from two case studies. In experiment “A” red mud from Ajka (Hungary) was mixed into acidic sandy soil in soil microcosms at 5–50 w/w%. In experiement “B” red mud soil mixture was mixed into low quality subsoil in a field experiment at 5–50 w/w%. According to average well color development, substrate average well color development and substrate richness 5–20% red mud increased the microbial activity of the acidic sandy soil over the short term, but the effect did not last for 10months. Shannon diversity index showed that red mud at up to 20% did not change microbial diversity over the short term, but the diversity decreased by the 10th month. 30–50% red mud had deteriorating effect on the soil microflora. 5–20% red mud soil mixture in the low quality subsoil had a long lasting enhancing effect on the microbial community based on all Biolog EcoPlate parameters. However, 50% red mud soil mixture caused a decrease in diversity and substrate richness. With the Biolog EcoPlate we were able to monitor the changes of the microbial community in red mud affected soils and to assess the amount of red mud and red mud soil mixture applicable for soil treatment in these cases.

The effect of pH, electrolytes and temperature on the rhizosphere geochemistry of phytosiderophores

Background and aimsGraminaceous plants are grown worldwide as staple crops under a variety of climatic and soil conditions. They release phytosiderophores for Fe acquisition (Strategy II). Aim of the present study was to uncover how the rhizosphere pH, background electrolyte and temperature affect the mobilization of Fe and other metals from soil by phytosiderophores.MethodsFor this purpose a series of kinetic batch interaction experiments with the phytosiderophore 2′-deoxymugineic acid (DMA), a calcareous clay soil and a mildly acidic sandy soil were performed. The temperature, electrolyte concentration and applied electrolyte cation were varied. The effect of pH was examined by applying two levels of lime and Cu to the acidic soil.ResultsFe mobilization by DMA increased by lime application, and was negatively affected by Cu amendment. Mobilization of Fe and other metals decreased with increasing ionic strength, and was lower for divalent than for monovalent electrolyte cations at equal ionic strength, due to higher adsorption of metal-DMA complexes to the soil. Metal mobilization rates increased with increasing temperature leading to a faster onset of competition; Fe was mobilized faster, but also became depleted faster at higher temperature. Temperature also affected biodegradation rates of metal-DMA complexes.ConclusionRhizosphere pH, electrolyte type and concentration and temperature can have a pronounced effect on Strategy II Fe acquisition by affecting the time and concentration ‘window of Fe uptake’ in which plants can benefit from phytosiderophore-mediated Fe uptake.

Applicability of zeolites in potassium and nitrate retention in different soil types

Environmental protection and sustainable agricultural production require the use of inexpensive and environmentally acceptable soil supplements. Objectives of this study were to investigate the influence of the addition of the natural zeolite ? clinoptilolite (NZ) and its iron(III)-modified form (FeZ) on the potassium and nitrate leaching from sandy, silty loam and silty clay soils. The zeolites were added in two amounts: 0.5 (FeZ) and 1.0 wt. % (NZ and FeZ). The experiments were carried out in columns organized in eight experimental systems containing unamended (control specimens) and amended soils. The concentration of K+ and NO3?N in the leachates was monitored during 7 days. The obtained results indicate that the K+ and NO3?N leaching mainly depends on the soil type and pH of the soil. The NZ and FeZ addition has the highest impact on the K+ retention in the acidic sandy soil. The highest NO3?N retention is obtained with FeZ in acidic silty loam soil. The K+ leaching kinetics for all the studied soils follow the Avrami kinetics model with the parameter n &lt; 1. This study demonstrates that NZ and FeZ can be a good soil supplement for the K+ retention for all studied soils and in the NO3?N retention for silty loam and silty clay soils.

Protoventuria arxii . [Descriptions of Fungi and Bacteria

Abstract A description is provided for Protoventuria arxii . This species has been recorded on living leaves where it is likely to be mildly parasitic and, more often, on attached and fallen dead leaves and twigs, in litter on sandy acid soil in domestic garden, parkland, botanical gardens and in mixed woodland. Some information on its associated organisms and substrata, habitats, dispersal and transmission and conservation status is given, along with details of its geographical distribution (North America (USA (Maine, New Hampshire)), Europe (Italy, Switzerland, UK)) and hosts ( Rhododendron spp.). No reports of negative economic impacts of this fungus have been found.

Effects of soil type and composition of rhizodeposits on rhizosphere priming phenomena

Inputs of fresh plant-derived C may stimulate microbially-mediated turnover of soil organic matter (SOM) in the rhizosphere. But studies of such ‘priming’ effects in artificial systems often produce conflicting results, depending on such variables as rates of substrate addition, substrate composition, whether pure compounds or mixtures of substrates are used, and whether the addition is pulsed or continuous. Studies in planted systems are less common, but also produce apparently conflicting results, and the mechanisms of these effects are poorly understood.To add to the evidence on these matters, we grew a C4 grass for 61 d in two contrasting soils – an acid sandy soil and a more fertile clay-loam – which had previously only supported C3 vegetation. We measured total soil respiration and its C isotope composition, and used the latter to partition the respiration between plant- and soil-C sources. We found SOM turnover was enhanced (i.e. positive priming) by plant growth in both soils. In treatments in which the grass was clipped, net growth was greatly diminished, and priming effects were correspondingly weak. In treatments without clipping, net plant growth, total soil respiration and SOM-derived respiration were all much greater. Further, SOM-derived respiration increased over time in parallel with increases in plant growth, but the increase was delayed in the less fertile soil. We conclude the observed priming effects were driven by microbial demand for N, fuelled by deposition of C substrate from roots and competition with roots for N. The extent of priming depended on soil type and plant growing conditions.In a further experiment, we simulated rhizodeposition of soluble microbial substrates in the same two soils with near-continuous additions for 19 d of either C4-labelled sucrose (i.e. a simple single substrate) or a maize root extract (i.e. a relatively diverse substrate), and we measured soil respiration and its C isotope signature. In the more fertile soil, sucrose induced increasingly positive priming effects over time, whereas the maize root extract produced declining priming effects over time. We suggest this was because N and other nutrients were provided from the mineralization of this more diverse substrate. In the less-fertile soil, microbial N demand was probably never satisfied by the combined mineralization from added substrate and soil organic matter. Therefore priming effects were approximately constant over time. We conclude that the chemical nature of putative priming compounds can greatly influence priming phenomena.

Content of selected elements and low-molecular-weight organic acids in fruiting bodies of edible mushroom Boletus badius (Fr.) Fr. from unpolluted and polluted areas.

The aim of the study was to (i) investigate the potential of edible mushroom Boletus badius (Fr.) Fr. to accumulate 53 elements from unpolluted acidic sandy soil and polluted alkaline flotation tailing sites in Poland, (ii) to estimate the low-molecular-weight organic acid (LMWOA) profile and contents in fruit bodies, and finally (iii) to explore the possible relationship between elements and LMWOA content in mushrooms. The content of most elements in fruiting bodies collected from the flotation tailings was significantly higher than in mushrooms from the unpolluted soils. The occurrence of elements determined in fruiting bodies of B. badius has been varied (from 0.01 mg kg−1 for Eu, Lu, and Te up to 18,932 mg kg−1 for K). The results established the high importance of element contents in substrate. Among ten organic acids, nine have been found in wide range: from below 0.01 mg kg−1 for fumaric acid to 14.8 mg g−1 for lactic acid. Lactic and succinic acids were dominant in both areas, and citric acid was also in high content in polluted area. The correlation between element contents and the individual and total content of LMWOAs was confirmed.Electronic supplementary materialThe online version of this article (doi:10.1007/s11356-016-7222-z) contains supplementary material, which is available to authorized users.

English

Studies on combined effects of 4 legume crops residues and rock phosphate application on pearl millet yield were undertaken on sandy acid soil field from 2012 to 2015 at ICRISAT Sahelian center (ISC)-Sadore, Niger. The objective of the experiment was to assess the best combination of legume species x rate of crop residue x rock phosphate doses that can sustainably improve pearl millet yield in cereal monoculture system with a low input cost and minimum soil tillage. Over 3 years, the residual effect of previous legume crop residue significantly improved not only the grain yield (P&lt;0.001) and dry residue yields (P&lt;0.001) but also the growth parameters of pearl millet than millet mono-cropping. Treatments with or without natural rock phosphate did not show any statistical differences on millet yield while adding a micro dose of urea improved significantly the yield (P&lt;0.001). The interaction effects of preceding legume crops in rotation with millet and restitution of dry residue on the earlier mentioned parameters across 3 years mono-cropping were studied in this experiment. &nbsp; Key words: Millet, legume, cropping system, soil fertility.

Effect of low‐temperature biochar derived from pig manure and poultry litter on mobile and organic matter‐bound forms of Cu, Cd, Pb and Zn in sandy soil

AbstractNumerous studies conducted so far have shown that biochar has a significant effect on physical, chemical and biological properties of soils. Biochar can be used to alleviate the effects of soil contamination with organic and inorganic compounds, for instance, to reduce the mobility of heavy metals. The aim of the research was to evaluate the effect of pig manure and poultry litter, as well as biochars produced from these materials at a temperature of 300 °C on Cu, Cd, Pb and Zn contents in mobile and organic matter‐bound forms in soil. The research was conducted under laboratory conditions. The materials were introduced into sandy acid soil in doses of 0.5, 1.0 and 2.0% w/w. The application of pig manure‐derived biochar (BPM) and poultry litter‐derived biochar (BPL), depending on the amount added, reduced the mobility of copper from 28 to 69%, from 77 to 100% in the case of cadmium, from 94 to 99% in the case of lead, and from 15 to 97% in the case of zinc. The 2% amendment of pig manure (PM) and poultry litter (PL) caused an increase in the content of Cu extracted with NH4NO3 in comparison with the control treatment. A similar situation was observed in the case of zinc after the application of 0.5 and 1% amendments of pig manure (PM). Cu, Cd, Pb and Zn contents extracted with 0.025 mol C10H22N4O8 were higher than contents of these elements extracted with 1 m NH4NO3, mainly due to different extraction force of the extractants. The obtained results indicate that, compared with the content determined in soil from the control treatment, 1 and 2% amendments of both unconverted and thermally converted materials to the soil had a greater effect on contents of Cu, Pb and Zn in the organic matter‐bound fraction than the 0.5% amendment. The organic materials applied did not affect the content of cadmium in organic matter‐bound fraction.

Complementary distribution patterns of arthropod detritivores (woodlice and millipedes) along forest edge‐to‐interior gradients

Abstract Worldwide, forest fragmentation induces edge effects, thereby strongly altering the forest microclimate and abiotic characteristics in the forest edge compared to the forest interior. The impact of edge‐to‐interior gradients on abiotic parameters has been extensively studied, but we lack insights on how biodiversity, and soil communities in particular, are structured along these gradients. Woodlice (Isopoda) and millipedes (Diplopoda) are dominant macro‐detritivores in temperate forests with acidic sandy soils. We investigated the distribution of these macro‐detritivores along forest edge‐to‐interior gradients in six different forest stands with sandy soils in northern Belgium. Woodlouse abundance decreased exponentially with distance from the forest edge, whereas millipede abundance did not begin to decrease until 7 m inside the forest stands. Overall, these patterns were highly species specific and could be linked to the species' desiccation tolerance. Whereas the observed abundance patterns were independent from forest stand and dominant tree species, tree species had a large effect on community structure. Edge gradients in macro‐detritivores may consequently have implications for nutrient cycling, especially in smaller forest fragments with a large edge‐to‐interior ratio.