Superficial Soil Layer Research Articles

SPATIAL AND VERTICAL DISTRIBUTION OF LITTER AND BELOWGROUND CARBON IN A BRAZILIAN CERRADO VEGETATION

ABSTRACT Forest ecosystems contribute significantly to store greenhouse gases. This paper aimed to investigate the spatial and vertical distribution of litter, roots, and soil carbon. We obtained biomass and carbon of compartments (litter, roots, and soil) in a vegetation from Cerrado biome, state of Minas Gerais, Brazil. The materials were collected in 7 0.5 m² sub-plots randomly allocated in the vegetation. Root and soil samples were taken from five soil layers across the 0-100 cm depth. Roots were classified into three diameter classes: fine (<5 mm), medium (5-10 mm), and coarse (>10 mm) roots. The carbon stock was mapped through geostatistical analysis. The results indicated averages of soil carbon stock of 208.5 Mg.ha-1 (94.6% of the total carbon), root carbon of 6.8 Mg.ha-1 (3.1%), and litter of 5 Mg.ha-1 (2.3%). The root carbon was majority stored in coarse roots (83%), followed by fine (10%), and medium roots (7%). The largest portion of fine roots concentrated in the 0-10 cm soil depth, whereas medium and coarse roots were majority in the 10-20 cm depth. The largest portion of soil (53%) and root (85%) carbon were stored in superficial soil layers (above 40 cm). As conclusion, the carbon spatial distribution follows a reasonable trend among the compartments. There is a vertical relation of which the deeper the soil layer, the lower the soil and root carbon stock. Excepting the shallowest layer, coarse roots held the largest portion of carbon across the evaluated soil layers.

Molecular characterization of environmental Cladosporium species isolated from Iran

Background and Purpose: Cladosporium species are ubiquitous, saprobic, dematiaceous fungi, only infrequently associated with human and animal opportunistic infections.Materials and Methods:Airborne samples were collected using the settle plate method, and soil samples were obtained from a depth of 5-10 cm of the superficial soil layer. Samples were cultured on Sabouraud dextrose agar (SDA) plates, incubated at 25°C, and examined daily for fungal colonies for two to three weeks. Isolates were identified as Cladosporium species according to the macroscopic and microscopic criteria. For species differentiation, DNA from 53 isolates was extracted and subjected to amplification of the internal transcribed spacer (ITS) region followed by sequencing.Results:A total of 270 samples were collected from various environmental sources, of which 79 strains of Cladosporium species were isolated. The most frequent species was C. cladosporioides (50.6%), followed by C. iridis (44.3%), C. elatum (2.5%), C. peranqestum (1.3%), and C. alicinum (1.3%).Conclusion: The collected data can serve as baseline information for future research and may be useful in the development of preventive and educational strategies.

Molecular characterization of environmental Cladosporium species isolated from Iran.

Cladosporium species are ubiquitous, saprobic, dematiaceous fungi, only infrequently associated with human and animal opportunistic infections. Airborne samples were collected using the settle plate method, and soil samples were obtained from a depth of 5-10 cm of the superficial soil layer. Samples were cultured on Sabouraud dextrose agar (SDA) plates, incubated at 25°C, and examined daily for fungal colonies for two to three weeks. Isolates were identified as Cladosporium species according to the macroscopic and microscopic criteria. For species differentiation, DNA from 53 isolates was extracted and subjected to amplification of the internal transcribed spacer (ITS) region followed by sequencing. A total of 270 samples were collected from various environmental sources, of which 79 strains of Cladosporium species were isolated. The most frequent species was C. cladosporioides (50.6%), followed by C. iridis (44.3%), C. elatum (2.5%), C. peranqestum (1.3%), and C. alicinum (1.3%). The collected data can serve as baseline information for future research and may be useful in the development of preventive and educational strategies.

Effects of tillage, crop rotation and N application rate on labile and recalcitrant soil carbon in a Mediterranean Vertisol

The quantification of labile and recalcitrant fractions of organic C could provide valuable information in the study of soil organic carbon (SOC) changes in agrosystems. Few studies have determined the effects of farming practices on the recalcitrant and labile fractions of SOC at depth in a Mediterranean Vertisol. Our objective was to determine the effects of tillage, crop rotation and N fertilization on labile and recalcitrant SOC fractions and characterize δ13C in a soil profile (0–120cm) from a long-term experiment established in 1986 on rainfed Mediterranean Vertisols in southern Spain. The following treatments were studied: conventional tillage (CT) vs. no-tillage (NT); three crop rotations (wheat [Triticum aestivum L.]–chickpea [Cicer arietinum L.], wheat–sunflower [Helianthus annuus L.] and wheat–faba-bean [Vicia faba L.]); and two N fertilizer application rates (0 and 100kgNha−1). The SOC contents of the soil samples from five soil layers (0–15, 15–30, 30–60, 60–90 and 90–120cm) were determined. Throughout the experiment, the SOC content was greater in surface than in deep layers. The NT resulted in a greater SOC content than CT (10.7Mgha−1 and 8Mgha−1, respectively) in the most superficial soil layer. The SOC content was greater in the recalcitrant fraction than in the labile fraction (62% and 38% of total SOC, respectively). The recalcitrant SOC fraction was greater under CT than under NT. In the uppermost 15cm, the labile organic C fraction was greater in the NT treatments than in the CT treatments because tillage resulted in a greater mineralization of the least stable forms of SOC. The influence of N rate and crop rotation on SOC was very low. The stable C isotopic composition (δ13C) was greater at depth than at the surface for both total SOC and the recalcitrant fraction. The labile fraction had more 13C than the recalcitrant fraction. The δ13C value was greater under CT than under NT for both soil fractions. Tillage system exerted a notable influence in both soil fractions and therefore in the organic matter quality since the labile fraction is an indicator of this quality.

Spacial distribution of fertigated coffee root system

ABSTRACT The development of coffee plant root system changes when subjected to drip irrigation and fertigation. This work aimed to evaluate the effects of different levels of fertigation on the development of coffee root system by drip irrigation in western Bahia. The experiment was carried out with Catuaí Vermelho IAC 144 coffee plants, of about 3.5 years of age, in the “Café do Rio Branco” farm, located in Barreiras - BA, and consisted of a complete randomized blocks design with 3 replicates. Treatments consisted of three levels of nitrogen and potassium fertilization (900/800, 600/500 and 300/250 kg ha-1 year-1 N and K2O), weekly distributed, by means of fertigation, throughout the process. After the fourth harvest, coffee root system was evaluated, and root length density (RLD) and root density (RD) were determined at different sampled layers. The highest root concentration, root length density (RLD), and root density (RD) were observed in the superficial layers of soil (0-20 cm), and under the dripline (30 and 70 cm from the orthotropic branch). Results showed that the lower the N and K2O levels, the higher was the development (RLD and RD) of the coffee root system.

Atributos físicos do neossolo regolítico distrófico sob pastagem submetido à colheita mecanizada da forragem e pastejo animal

O pastejo de bovinos e a utilização de máquinas em várias operações de preparo, semeadura, tratos culturais, colheita, entre outros, nos solos brasileiros tem sido apontada como a principal causa da compactação. Esse efeito reduz o crescimento e o desenvolvimento radicular, aumenta a perda de nitrogênio por desnitrificação e a erosão do solo pela menor infiltração de água. Diante disso, objetivou-se determinar e avaliar os atributos físicos e a velocidade de infiltração básica de água em um Neossolo Regolítico sob pastagem com diferentes formas de manejo (área sob pastejo extensivo e colheita mecanizada de forragem). O estudo foi conduzido na Fazenda Roçadinho, município de Capoeiras, Agreste de Pernambuco, sob pastagem com capim Búffel (Cenchrus ciliares L.) em pastejo contínuo de bovinos, com lotação média de 2 unidades animais (vacas leiteiras com peso vivo médio de 450 kg), e sob cultivo da mesma forrageira, ambos estabelecidos há mais de 5 anos, com colheita mecanizada da forragem, com a colhedora acoplada ao reboque do trator e com engate para carreta. O delineamento experimental utilizado foi inteiramente casualizado, aplicando-se o teste F a 5% de significância. O pastejo contínuo ocasionou maior resistência à penetração e densidade e menor porosidade do solo em comparação à área onde é realizada a colheita mecanizada de forragem, assim como uma menor velocidade de
 infiltração básica do solo. O pisoteio animal causa maior compactação do solo quando comparado à colheita mecanizada de forragem, portanto, a área de pastejo extensivo apresenta maior resistência à penetração e densidade, e obtém menor porosidade total e velocidade de infiltração da água na camada superficial do solo.

Ant assemblage and morphological traits differ in response to soil compaction

Soil compaction, a process that decreases the free space among soil particles and hinders the underground movement of soil organisms, is one of the increasing impacts of mankind on the world’s ecosystems. We investigated the responses of subterranean ants to soil compaction by testing the following predictions: (i) soil from a trail is more compressed, leading to (ii) a decrease in species richness and a selective shift in ant assemblage composition, which is made up by (iii) species with a smaller body size that can apply a greater relative strength to move through soil particles. We carried out this study in and outside of a recreational ecology trail in a forest fragment in Vicosa, MG, Southeastern Brazil. The compaction was higher in the soil from the trail than outside of it. No change was observed in species richness, but soil compaction promoted a shift in ant assemblage composition, with ant size decreasing with an increase in soil compaction. However, ants did not appear to apply a greater strength to soil particles for moving in habitats with a high soil compaction. Overall, organisms at superficial soil layers appeared to be sensitive to even moderate human impacts that promote a filtering of the ant assemblage species composition, with small body size being a required trait.

Influência de renques de mogno africano nos atributos físicos e teor de carbono orgânico de um latossolo amarelo

The objective was to evaluate the rows effect of African mahogany ( Khaya ivorensis ) and different soil management systems in physical attributes and organic carbon of a Typic. The treatments evaluated were integration system Crop-Livestock-Forest (iLPF) at two years of cultivation, being sampled at two distances, 2.5 m forest row (iLPF2.5) and 10 m (iLPF10), at a Forest monocropping with African mahogany (AM), with two years of cultivation, in Santa Fe system (SSF) and natural forest as control treatment (NF). The attributes of the soil evaluated were organic carbon, soil bulk density, total porosity, macroporosity and microporosity. The higher content of soil organic carbon was found in the superficial layer of soil, with progressive reduction in depth. The iLPF2.5 treatments, iLPF10 and SSF showed better physical condition of soil density and porosity than the AM compared to NF. There was difference on macroporosity only in the layers 0-10 cm, taking AF the less value, and 30-50 cm, with value largest stated by iLPF2.5. In microporosity, there was difference only in the 20-30 cm depth, with higher values in MN, SSF and iLPF10. The African mahogany rows in iLPF system improved the soil physical attributes in depth. The iLPF system and the SSF obtained the best density conditions and porosity of the soil and levels of soil organic carbon. The AM promoted organic carbon accumulation, however, had a negative impact on density and porosity of the soil. Normal 0 21 false false false PT-BR X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:Tabela normal; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:Calibri,sans-serif;}

Seasonal patterns in water uptake for Medicago sativa grown along an elevation gradient with shallow groundwater table in Yanchi county of Ningxia, Northwest China

Lucerne (Medicago sativa L.) is a deep-rooted perennial leguminous forage with high evapo-transpiration rate exceeding the annual precipitation in semi-arid areas of Northwest China. Groundwater might be the potential water sources of lucerne in the area with shallow groundwater table. In this study, stable isotopic compositions of oxygen and hydrogen (δ18O and δD) of different water sources and xylem sap were analyzed to determine the seasonal (April, June, July and August) and topographic (three slope positions) variations in water sources for lucerne growing in Ningxia eastern semi-arid area adjacent to Mu Us Desert characterized by shallow groundwater table. IsoSource software was used to calculate the probable contribution of different water sources to the total plant water uptake. Stomatal conductance, stem water potential, carbon isotope discrimination (Δ13C) of whole plant were also determined for evaluating the water status of lucerne growing at different slope positions. The results showed that soil water content increased as the elevation decreased. Oxygen compositions of soil water in the 0–40 cm profile fluctuated considerably. Soil water δ18O values in deep profile (>3.5 m) were similar to those in groundwater, implying the recharge of groundwater to this soil layer. Highest water utilization rate from deep soil profile (below 350 cm) was recorded for lucerne grown at the slope position 1 (groundwater table depth of 3.5–3.9 m) in April, June and July. The lucernes at slope position 2 (groundwater table depth of 5.8–6.4 m) and slope position 3 (groundwater table depth 7.1–8.3 m) mostly used water from deep soil layers (below 350 cm) during dry period, and turned to use water from superficial soil layer in wet period. Higher yield, Δ13C value of whole plant and stomatal conductance were observed for lucerne grown at the slope position 1 than those at other slope positions. These results indicated that groundwater is a significant water source for transpiration of lucerne grown in Ningxia semi-arid area with shallow groundwater table where lucerne grassland is suggested to be established so as to obtain better yield performance.

The effect of Robinia pseudoacacia afforestation on soil and vegetation properties in the Loess Plateau (China): A chronosequence approach

Revegetation is one of the primary management approaches for solving the problems caused by severe soil erosion worldwide. Robinia pseudoacacia was considered a promising tree for afforestation in the highly eroded region of the Loess Plateau due to its fast growth and ability to fix atmospheric nitrogen. However, its beneficial role protecting soils from erosion has been now questioned and several negative effects on soil and vegetation have been described. In this study we aimed to analyze the effects of R. pseudoacacia plantation on plant community composition and dynamics through the effects that R. pseudoacacia has on light, soil fertility and soil water availability. We used a chronosequence from 10–40-year-old plantations and compared the environmental and vegetation characteristics of that areas with that of natural control areas with similar age. The results showed that R. pseudoacacia plantations reached maturity around 30years and then declined in density and canopy cover. We also found that soil nutrients and moisture at the superficial soil layer improved with age until maturity of plantations, but photosynthetically active radiation at the ground level and soil moisture at deeper soil layers decreased with maturity in relation to control conditions. Plots with R. pseudoacacia of all ages had higher cover values, lower number of species but higher β-diversity values than control conditions and they also differed in species composition. These differences in structure and species composition were related to the fertilizer effect of R. pseudoacacia that favored colonization by weeds and ruderal species, and to the light interception by the canopy of trees that exclude light-demanding species, most of them perennial herbaceous species which were the dominant species in control conditions.

Phosphorus fractions in an agricultural chronosequence under tillage regimes in the Cerrado area in Goiás, Brazil

The increase in the amount and quantity of soil organic matter (SOM), as well as the use of phosphorus-based fertilizers in the superficial soil layer in areas under tillage regimes (TR), may affect phosphorus (P) dynamics in the soil. Therefore, the aims of the present work were as follows: to evaluate the inorganic and organic fractions of P and its lability levels (labile, moderately labile, and moderately resistant) in a Distroferric Red Latosol under tillage regimes (TR) 3, 15, and 20 years after implementation, and to compare them with those of areas of native Cerrado and pastures. We also focus on analyzing the correlations of the P fractions in these areas with other soil attributes, such as total carbon and nitrogen levels, light organic matter (LOM), chemical and physical granulometric fractions of the SOM, maximum phosphate adsorption capacity (MPAC), and the remaining phosphorus (Prem). In each of these areas, samples were collected from the 0.0-0.05 and 0.05-0.10 m soil layers. An entirely randomized experimental design was used. After TR implementation, the constant use of phosphorus-based fertilizers as well as the incremental addition of SOM resulted in an increase in the levels of labile, moderate labile, and moderately resistant organic and inorganic P, with a tendency for total P accumulation to be mostly in the inorganic, moderately labile form. The native Cerrado soil presented high levels of labile and moderately labile inorganic P. Pasture areas presented the lowest levels of labile organic and inorganic P, as well as moderately labile and moderately resistant organic P. By principal component analysis (PCA), it was possible to observe alterations in all soil attributes and P levels of the fractions analyzed.

Numerical Evaluation of Earthquake Settlements of Road Embankments and Mitigation by Preloading

AbstractThis article presents an assessment of the effects of pore water pressure generation of the soil foundation on the seismic road embankment response. Numerical simulations were carried out to study the preloading technique as an improvement method for reducing the liquefaction potential and the induced settlements in a sandy soil profile. The analyses showed that the use of preloading reduces the induced settlements mostly because of the increase in lateral confinement in the superficial soil layers that results from an increase of the coefficient of lateral earth pressure at rest (ko). The research also showed that the efficiency of the countermeasure method was limited to cases in which earthquakes produced a liquefaction zone lower than the depth of the overconsolidated soil.

Least limiting water range and soybean yield in a long-term, no-till, integrated crop-livestock system under different grazing intensities

Crop-livestock integrated systems possess some uniqueness in soil and plant hydro-physical properties and processes. To obtain a better understanding of these systems, it is necessary to evaluate them with indices that take into account several attributes. Our study aimed to evaluate the efficiency of the least limiting water range in determining the influence of grazing intensities on soybean yield in an Oxisol managed in a long no-till, integrated soybean-beef cattle system. We evaluated an 11 year trial located in southern Brazil, with soybean summer cropping and black oat+Italian ryegrass winter grazing and different winter grazing intensities, namely intensive, moderate and no grazing. Intensive grazing only results in the most superficial soil layer compaction. Long-term moderate grazing, on the other hand, leads to intermediate compaction, not negatively affecting surface or subsurface soil physical properties. The least limiting water range is an inadequate indicator of soil physical quality in integrated soybean-beef cattle system, provided no direct relations with soybean yields. Under normal rainfall conditions, soybean yield depend mainly on rainfall amount and distribution, rather than on soil quality.

Effects on the composition and structural properties of the humified organic matter of soil in sugarcane strawburning: A chronosequence study in the Brazilian Cerrado of Goiás State

The heating of soil organic matter after burning events can significantly change the composition and structure of humified organic matter. The impact of burning on the amount and quality of SOM depends on fire intensity, recurrence, the type of vegetation, soil texture and the local climate. The present study identified the composition and structural properties of humic acids (HA) extracted from a sandy loam textured Latossolo Vermelho (Oxisol) managed with the pre-harvest burning of sugarcane straw for chronosequences of 1, 5, 10 and 20 years in Rio Verde, Goiás (GO). Soil samples were collected at depths of 0–0.05, 0.05–0.10, 0.10–0.20 and 0.20–0.30m. To obtain a reference of natural conditions, soil was also sampled in adjacent areas covered with native vegetation and Pasture grass. The HA samples from soil under different burning conditions and areas (Cerrado and Pasture grass) were analyzed using chemical-spectroscopic characterization and the chemiometric technique. The greatest modifications in HA composition after burning occurred in the most superficial soil layers. At a depth of 0.0–0.05m, the main changes observed were a decrease in mean C and N levels and enrichment in O, irrespective of the length of time that burning practices had been adopted. Additionally, in the most superficial layer, the ultraviolet-visible spectroscopy assay showed that burning enhanced the aromatic properties (<E4/E6) of HA, and FTIR spectroscopy coupled with PCA confirmed that the top soil layer shows higher variations in the functional groups as a function of burning. The PCA analysis of 13C NMR spectra also showed that stronger aromatic properties were found in the most superficial layer, and the PCA of FTIR spectra reinforced the result by grouping HAs in these layers and thereby indicated that the most intense changes occurred in the 0.0–0.05m layer. The most intense disturbances produced by sugarcane burning on the composition and structure of humified organic matter occurred in the most superficial layer. The combined use of the methods adopted was efficient and, along with the chemiometric techniques, consisted of useful tools that can support the development of procedures to study phenomena such as burning.

Maximum Phosphorus Adsorption Capacity Adjusted to Isotherm Models in Representative Soils of Eastern Amazon

Most soils of the Amazon present low natural fertility and may also present high phosphorus (P)–fixation capacity. Clay fraction mineralogy, organic carbon, cation exchange capacity (CEC), and pH are among the factors that influence P adsorption. In this study, we aimed to evaluate the maximum P-adsorption capacity (MPAC) and correlate parameters of the isotherm models and the MPAC with soil attributes. Soil samples were collected in 12 forest soils in the state of Pará. We built Langmuir and Freundlich isotherms, and their parameters correlated with soil attributes. MPAC was greater in Plinthosols, among the soils studied at both depths. In superficial soil layers, the parameters of Langmuir-Freundlich equations correlated with clay content, pH, organic matter (OM), aluminum oxide (Al2O3), and iron oxide (Fe2O3) at both depths. The Langmuir model is more representative of the adsorption of P relative to the Freundlich model for the Amazon region soils, where it is necessary to make use of organic matter and pH control as a means of reducing the retention and P and maximize the effects of fertilization phosphate.

Temporal dynamics of runoff and soil loss on a plot scale under a coffee plantation on steep soil (Ultisol), Costa Rica

Soil erosion is a serious threat for cultivated soils on steep slopes under tropical conditions. In Costa Rica, coffee plantations are widespread on such steep slopes in several basins used for hydroelectric generation, which are affected by soil erosion and sedimentation in dam reservoirs. For this study, surface runoff and soil loss rate were measured during three years on large experimental plots installed within a coffee field on a steep slope (60% average). The time interval for rainfall and runoff measurements was 5 min. A simple infiltration model presented by Diskin and Nazimov (1995) was used to estimate runoff during a rainfall event showing the relevance of initial soil water content in order to estimate runoff base on rainfall intensity variations. Three complementary embedded time scales were analyzed: annual-monthly, event and intra-event. The rainy seasons included 581 rainfall events giving a total depth of 2206, 1778 and 2220 mm in 2011, 2012 and 2013 respectively. Total runoff was 103 ± 55, 54 ± 14 and 33 ± 6.4 mm in 2011, 2012 and 2013 respectively. Annual average sediment concentration was about 1.3 ± 0.3 g l?1 with reduced temporal variations between years or rainfall events. The total soil loss was 1686 ± 784, 914 ± 306 and 575 ± 140 kg ha?1 for 2011, 2012 and 2013 respectively. Around 60% of rainfall and 90% of runoff and soil loss respectively came from the August-October period and more than half of it from October. Total rainfall event and soil water content explained most of surface runoff and soil loss dynamics at three time scales analyzed. Inherited soil water storage from previous year played an important role on the relationship between rainfall and runoff dynamics the following year. Soil and coffee coverage did not have a significant effect on runoff and soil loss variability due to permanently good soil coverage (even in the rainy season). This good coverage over the rainy season prevented crust development. The presence of old micro-terraces helped to reduce runoff and sediment loss. The Diskin and Nazimov model demonstrated that a combination of rainfall intensity and soil water content dynamics on an intra-event scale explained better the differences observed in runoff and soil loss on an inter-event scale. Runoff at intra event scale had high and low runoff moments depending on rainfall intensity and superficial soil layer water status and saturation of deeper layers under long rainfall events. (Resume d'auteur)

&lt;b&gt;Effects on soil chemical attributes and cotton yield from ammonium sulfate and cover crops

Fertilizer use in no-till systems must be aligned with a correct interpretation of soil chemical attributes and crop demands. The objectives of this work were evaluate the effects of pre-sowing application of ammonium sulfate (AS) and of cover crops on the yields and soil chemical attributes of no-till cotton (Gossypium hirsutum L. r. latifolium Hutch) over two harvesting years. The experiment was arranged in randomized complete block design, with the plots in strips, and the variables were three cover crops (Raphanus sativus L., Avena strigosa L. and Avena sativa L.) and four AS doses (0, 150, 300, and 450 kg ha-1) applied over millet dry biomass. The cotton in the experimental plots was manually harvested on April 25, 2007 and April 24, 2008. The soil samples were collected between cotton rows in all plots on May 5, 2007 and May 12, 2008, at depths of 0.0-0.05, 0.05-0.10, and 0.10-0.20 m for soil fertility analyses. The increasing doses of AS induced lower soil pH, and calcium (Ca) and magnesium (Mg) levels in the superficial soil layer, as well as higher exchangeable aluminum (Al) and sulfur (S) levels until a depth of0.20 m. Seed cotton yields increased with increasing AS doses.

Accumulation of copper and zinc fractions in vineyard soil in the mid-western region of Santa Catarina, Brazil

The application of fungicides to grapevines can cause the accumulation of Cu and Zn fractions in soil and increase their bioavailability and toxicity for plants. This study evaluated the accumulation and distribution of Cu and Zn fractions in the soil profile of a vineyard. In January 2012, stratified samples were collected from a 95-year-old vineyard and from a forest, which was used as a reference. The soil was dried, ground, and subjected to an analysis of chemical properties and chemical fractionation of Cu and Zn. Cu and Zn accumulated in the most superficial soil layers of the control area and vineyards; greater amounts were found in the soil of vineyards with more than 90 years of Bordeaux mixture application. Most of the Cu and Zn in the control area and vineyard soils were distributed in the residual fraction, with low geochemical mobility; however, they were also found in the most superficial layers of the vineyard soil. There were increases in the contents of soluble Cu, exchangeable Cu, and Cu bond to organic matter of the vineyard soil, especially in the most superficial layer of the soil. Most of the Zn in the vineyard soil was distributed in the residual fraction and bound to minerals, with low mobility but potential toxicity to plants.

Neutralization of arsenic wastes from mining and metallurgical industry

The authors deal with the problem of pollution of the town of Svirsk (Siberia, Russian Federation) with toxic wastes from mining and metallurgical industry. Areas of heavy metal pollution of superficial soil layers are established. The principal technological approaches to neutralization of the pollution source are presented.

Root system distribution and yield of 'Conilon' coffee propagated by seeds or cuttings

The objective of this work was to evaluate the root system distribution and the yield of 'Conilon' coffee (Coffea canephora) propagated by seeds or cuttings. The experiment was carried out with 2x1 m spacing, in an Oxisol with sandy clay loam texture. A randomized complete block design was used, following a 2x9x6 factorial arrangement, with two propagation methods (seeds and cuttings), nine sampling spacings (0.15, 0.30, 0.45, 0.60, 0.75, and 0.90 m between rows, and 0.15, 0.30, and 0.45 between plants within rows), six soil depths (0.10-0.20, 0.20-0.30, 0.30-0.40, 0.40-0.50, and 0.50-0.60 m), and six replicates. Soil cores (27 cm3) with roots were taken from 12 experimental units, 146 months after planting. The surface area of the root system and root diameter, length, and volume were assessed for 13 years and, then, correlated with grain yield. The highest fine root concentration occurred at the superficial soil layers. The variables used to characterize the root system did not differ between propagation methods. Moreover, no differences were observed for net photosynthetic CO2 assimilation rate, stomatal conductance, internal CO2 concentrations, and instantaneous water-use efficiency in the leaves. Cutting-propagated plants were more productive than seed-propagated ones.