Edivan Rodrigues de Souza

Comparação de métodos de extração da solução do solo

The ionic composition of the soil solution is of great importance for monitoring the availability of nutrients and fertilizer management, as well as processes of environmental contamination. Thus, the most viable methods to estimate the composition of the soil solution are well accepted in the literature. This study aims to evaluate the performance of the extraction methods by saturation paste, porous extractor cups and soil:water relations of 1:2, 1:5 and 1:10, with and without filtering process. Samples of Fluvic Neossol were used in PVC columns and saturated with solutions corresponding to 0, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110 and 120 mmolc L-1 NaCl, in randomized block design with four replications. The extractors with porous cup are indicated to extract the soil solution for monitoring the electrical conductivity, osmotic potential and ionic composition. The aqueous extract in different soil:water ratio has a potential use for the extraction and subsequent characterization of the aqueous phase of soil. The filtering process can be discarded when the intention is only to determine the electrical conductivity.

Fitoextração de sais pela Atriplex nummularia lindl. sob estresse hídrico em solo salino sódico

This study aims to evaluate the growth, production and extraction of salts by Atriplex grown on saline-sodic soil under water stress conditions and to compare soil properties before and after their cultivation. The experiment was carried out in a greenhouse during 134 days growing Atriplex nummularia in pots with 20 kg of saline sodic soil with four levels of soil moisture (35, 55, 75 and 95% of field capacity) with a control (soil without plant). The experiment was performed in a randomized block with eight replications. The high concentrations of Ca2+, Mg2+, K+, and especially Na+ and Cl- in leaves of Atriplex nummularia, associated with high dry matter production characterizes this species as phytoextraction of salts, extracting through leaf and stem: 644, 758, 1059 and 1182 kg ha-1 at 35, 55, 75 e 95% of field capacity, respectively. The variables of the exchangeable cations (Ca2+, Mg2+, K+, sum of bases) and total organic carbon remained stable between the beginning and end of the experiment in all treatments, while Na+ and exchangeable sodium percentage decreased after cultivation of the plant. The Atriplex responded to soil moisture with respect to biomass production and salts extraction.

Qualidade física de Latossolo Amarelo de tabuleiros costeiros em diferentes sistemas de manejo da cana-de-açúcar

The physical attributes are important indicators to evaluate management systems. The objective of this research was to study alterations in the soil properties of the distrophic cohesive yellow Oxisol of a coastal plain in Alagoas state, Brazil, cultivated with sugarcane. Plots were selected in the following sugarcane-growing areas: area under irrigation management system (IMS), area fertigated with vinasse (FV), and area under application of vinasse + filter cake (V + FC). These management systems were compared to each other and to a control (native forest). The bulk soil density, total porosity, weighted mean diameter of the aggregates, hydraulic conductivity, total organic carbon and compaction degree were evaluated in 0-0.20; 0.20-0.40 e 0.40-0.60 m depths. The results showed that management system that receives residues of the sugarcane presents alterations in the physical properties of soil more adequate for development of sugarcane. Among the evaluated systems, little physical degradation was observed in area with application of vinasse + filter cake followed by area with application of vinasse.

Variabilidade espacial das frações granulométricas e da salinidade em um Neossolo Flúvico do semi-árido

Analysis of the physical attributes and salinity of soils is important for proposing management strategies in irrigated areas. The objective of this study was to evaluate the spatial dependence of the granulometric fractions and electric conductivity of the saturation extract in an area irrigated in the semi-arid of Pernambuco State. A 5 x 5m regular mesh was adopted, with 98 sampling points collected at depth 0-20cm. The variables have been analysed through statistics and geoestatistics. The variation coefficients of the saturation extract were 26.08; 14.81; 16.01 and 28.00% for sand, clay, silt and electrical conductivity of the saturation extract, respectively. The spatial dependence was identified as high for the granulometric fractions and as moderate for the electric conductivity, with ranges of 56; 50 and 55 and 35m, respectively. The electric conductivity has a strong spatial correlation with silt content, presenting range of 52m, for the cross semivariogram. The results highlight the importance of the silt fraction in the spatial distribution of salinity in loam soils, and its relevance for adequate management of these soils.

Ponto de murcha permanente fisiológico e potencial osmótico de feijão caupi cultivado em solos salinizados

Com o objetivo de avaliar o ponto de murcha permanente fisiologico, a umidade foliar e o potencial osmotico no feijoeiro caupi, sob duas condicoes de estresses (salino e salino + hidrico), foram conduzidos dois experimentos em casa de vegetacao na Universidade Federal Rural de Pernambuco (Recife, PE, Brasil). O delineamento experimental adotado foi o inteiramente casualizado, em arranjo fatorial 2 x 4, sendo duas classes texturais de solos (franco-arenoso e franco-argiloso) e quatro niveis de salinidade do solo, equivalentes as condutividades eletricas do extrato de saturacao do solo 4, 8 e 12 dS m

Evolução e variabilidade espacial da salinidade em Neossolo Flúvico cultivado com cenoura sob irrigação

A field experiment was carried out aiming to verify the effect of micro sprinkler irrigation, using water with an average electrical conductivity of 1.42 dS m-1, on the chemical properties of a Fluvic Neossol cropped with carrot, variety Brasilia. The area was divided into two sectors (S1 and S2), each one with 900 m2 (30 x 30 m) and contrasting textures; at S2 mulch was added at day 23 after sowing (DAS). A leaching fraction of 0.20 was adopted for both sectors. Two soil sampling schemes were carried out, before sowing and at 96 DAS, in the 0-20 and 20-40 cm layers, at 49 points in S1 and 52 points in S2, according to a regular 5 x 5 m mesh. In the extract of saturated soil paste, pH and electrical conductivity (ECse) were measured, and exchangeable cations in soil were evaluated; in addition, the sodium adsorption ratio and the exchangeable sodium percentage were calculated. Data has been analysed using descriptive statistics and geostatistics. Considering the 0-40 cm layer, the saline area at S1, covering 7.98% at the beginning, increased to 15.09% by the end of the cropping period. For S2, the percentage of saline area shifted from 5.97% to 5.52%. The decisive influence of texture and mulch for the control of soil salinity has thus been verified.

Structural quality of polyacrylamide-treated cohesive soils in the coastal tablelands of Pernambuco

Water-soluble polymers are characterized as effective flocculating agents due to their molecular features. Their application to soils with horizons with structural problems, e.g, a cohesive character, contributes to improvements in the physical quality and thus to the agricultural suitability of such soils. The purpose of this study was to evaluate the structural quality of soils with cohesive horizons of coastal tablelands in the State of Pernambuco treated with polyacrylamide (PAM) as chemical soil conditioner. To this end, three horizons (one cohesive and two non-cohesive) of a Yellow Argisol (Ultisol) were evaluated and to compare cohesive horizons, the horizon of a Yellow Latosol (Oxisol) was selected. The treatments consisted of aqueous PAM solutions (12.5; 50.0; 100.0 mg kg-1) and distilled water (control). The structural aspects of the horizons were evaluated by the stability (soil mass retained in five diameter classes), aggregate distribution per size class (mean weight diameter- MWD, geometric mean diameter - GMD) and the magnitude of the changes introduced by PAM by measuring the sensitivity index (Si). Aqueous PAM solutions increased aggregate stability in the largest evaluated diameter class of the cohesive and non-cohesive horizons, resulting in higher MWD and GMD, with highest efficiency of the 100 mg kg-1 solution. The cohesive horizon Bt1 in the Ultisol was most sensitive to the action of PAM, where highest Si values were found, but the structural quality of the BA horizon of the Oxisol was better in terms of stability and aggregate size distribution.

Water potential in soil and Atriplex nummularia (phytoremediator halophyte) under drought and salt stresses

ABSTRACT Atriplex nummularia is a halophyte widely employed to recover saline soils and was used as a model to evaluate the water potentials in the soil-plant system under drought and salt stresses. Potted plants grown under 70 and 37% of field capacity irrigated with solutions of NaCl and of a mixture of NaCl, KCl, MgCl2 and CaCl2 reproducing six electrical conductivity (EC): 0, 5, 10, 20, 30, and 40 dS m−1. After 100 days, total water (Ψw, plant) and osmotic (Ψo, plant) potentials at predawn and midday and Ψo, soil, matric potential (Ψm, soil) and Ψw, soil were determined. The type of ion in the irrigation water did not influence the soil potential, but was altered by EC. The soil Ψo component was the largest contributor to Ψw, soil. Atriplex is surviving ECs close to 40 dS m−1 due to the decrease in the Ψw. The plants reached a Ψw of approximately −8 MPa. The water potentials determined for different moisture levels, EC levels and salt types showed huge importance for the management of this species in semiarid regions and can be used to recover salt affected soils.

REDUÇÃO DA EROSÃO EM CULTIVO DE SORGO COM COBERTURA MORTA

Researches evaluating the use of mulch has contributing to optimize soil management towards sustainability, and improving soil quality. The objective of this study was to evaluate the efficiency of mulching on the reduction of erosion in a soil with sorghum (Sorghum bicolor L. Moench) crops subjected to simulated rainfall and increased soil organic carbon. The experiment was carried out from August to December 2013 under field conditions, using a randomized block design with three replications. The treatments consisted of sorghum with mulch, using the local vegetation available in the area; and sorghum without mulch. Simulated rainfalls were performed in three different periods of the crop cycle (initial, intermediate, and final), using a rainfall simulator. The use of mulch in soils with sorghum crops was efficient in improving soil water retention in all phases of the crop, and maintaining soil moisture during the rainfall intervals used, resulting in the absence of plant water loss, and greater contribution to soil organic carbon.

Pressure-volume (P-V) curves in Atriplex nummularia Lindl. for evaluation of osmotic adjustment and water status under saline conditions

The survival of Atriplex nummularia plants in saline environments is possible mainly due to the presence of salt-accumulating epidermal vesicles. Commonly, destructive methods, such as plant material maceration and subsequent reading in osmometers, are employed in studies on water relations and osmotic adjustment and are inconvenient due to their underestimation of the total water potential inside the cells, which can cause overestimation of an osmotic adjustment that is not present. As a result, methods that preserve leaf structure, such as pressure-volume (P-V) curves, which take into consideration only the salts that compose the symplastic solution, are more adequate. Thus, the main objectives of this study were to evaluate the effect of determination methods of osmotic potential (Ψo) in Atriplex nummularia through destructive and leaf structure-preserving techniques and to determine the water relations of the species under increasing NaCl concentrations. Plants were subjected to daily irrigations, maintaining soil moisture at 80% of field capacity, with solutions of increasing NaCl concentration (0, 0.05, 0.1, 0.2, 0.25 and 0.3 M) for 84 days. Water potential, osmotic potential and osmotic adjustment were determined. In addition, P-V curves were constructed using pressure chambers. Water and osmotic potentials decreased linearly with increasing NaCl concentration in the irrigation solution. The main discrepancies observed were related to the osmotic adjustments determined through maceration and P-V curves. Based on the present research, it was possible to conclude that in studies with species that have salt-accumulating vesicles in the epidermis, such as the plants in the genus Atriplex, constructing P-V curves is more adequate than destructive methods.