Maria Betânia Galvão dos Santos Freire

Estimativa do risco de sodificação de solos de Pernambuco pelo uso de águas salinas

An experiment was carried out in permeameters provided with vertical column and constant hydraulic head in order to evaluate sodification risks of soils with contrasting characteristics and treated with solutions of different electrical conductivities (EC) and sodium adsorption ratios (SAR). The treatments consisted of nine soils and eighteen percolating solutions with three EC values (175, 500 and 1,500 μS cm -1 ) and six SAR values (0 to 30 for sandy soils, 0 to 25 for medium textured soils and 0 to 15 for clay textured soils). Initially, the adjustment of the Na:Ca ratio on the cation exchange complex of the soils was performed using solutions with concentration of 50 mmol c L -1 . Later on leaching with solutions of different EC but same SAR was maintained to reach steady state flow, when the permeameters were dismantled and the soil samples removed for chemical analysis. Exchangeable sodium and cation exchange capacity were determined to calculate exchangeable sodium ratio (ESR) and exchangeable sodium percentage (ESP). Equations were adjusted between either ESR or ESP with EC and SAR of the percolating solution, the increment of EC and SAR elevated the soil ESR and the ESP. It may be concluded that the correct assessment of the sodification hazard has to take into consideration the soil properties and the water quality.

Condutividade hidráulica de solos de Pernambuco em resposta à condutividade elétrica e RAS da água de irrigação

An experiment was carried out in permeameters provided on vertical soil columns with constant hydraulic head in order to evaluate the hydraulic conductivity of soils with contrasting characteristics, and treated with solutions of different electrical conductivities (EC) and sodium adsorption ratios (SAR). The treatments consisted of nine soils, three EC values (175, 500 and 1.500 mS cm-1) and six SAR values of the irrigation water (0 to 30 for sandy soils, 0 to 25 for medium textured soils, and 0 to 15 for clay textured soils). Initially, an adjustment of the Na:Ca ratio in the cation exchange complex was performed with solutions at concentration of 50 mmolc L-1. The saturated hydraulic conductivity of soil (K0) was measured and the relative hydraulic conductivity (K0R) was determined, considering the maximum average K0 values of each soil as 100%. The K0R values were related to CE and SAR of the treatments, by adjusting the response surfaces. The correlation between K0 and the exchangeable sodium percentage (ESP) showed an inverse relationship between both variables in most of the studied soils. The increment in SAR resulted in the decrease of the K0R. It was not possible to define just one ESP value in order to establish a limit for sodic soils. ESP should be considered together with the EC of the irrigation water, as well as soil properties such as texture and mineralogy.

FITORREMEDIAÇÃO DE SOLO SALINO SÓDICO POR Atriplex nummularia E GESSO DE JAZIDA (1)

The cultivation of Atriplex nummularia on saline-sodic soils is economically attractive because it can be used as a forage crop as well as in landscape projects. The potential of Atriplex nummularia for phytoextraction of Na+ from a saline-sodic soil irrigated with saline water was evaluated. Additionally, gypsum was tested for improving phytoremediation. The experiment was set up as a randomized block design, in a 2 x 3 factorial scheme. The treatments consisted of: no gypsum and 50 % of the regularly recommended gypsum dose, and three salinity levels of irrigation water: C1 = 175 μS cm -1; C2 = 500 μS cm -1; C3 = 1,500 μS cm -1. The Na concentration in plant tissues and soil were evaluated 40, 70, 100 and 130 days after A nummularia transplanting. The results showed that there was a 96 % increase in root dry matter as a result of gypsum application. Sodium accumulation in shoots increased significantly in the third (90.1 g kg-1) and fourth (109.7 g kg-1) sampling period. This effect was magnified by gypsum application. After 100 days, the soil Na+ content had decreased by 31 and 26 %, with and without gypsum addition, respectively. Our results indicate that A. Nummularia is a Na+ accumulator species. Gypsum was effective as a phytoextraction enhancer. A. nummularia irrigation aiming at Na phytoremediation is possible with saline water varying from 175 to 1,500 μS cm-1.

Acúmulo e alocação de nutrientes em cana-de-açúcar

The objective of this study was to evaluate, along the first cycle of sugar cane, the capacity of eleven varieties of sugar cane (SP79-1011; RB813804; RB863129; RB872552; RB943365; RB72454; RB763710; SP78-4764; SP81-3250; RB867515 and RB92579), cultivated under full irrigation,the accumulation of the nutrients N, P, K, Ca and Mg in the plants aerial parts (stem, leaf and pointer). The research was carried through under field conditions, during the agricultural season 2006/2007, in the Sugar Cane Agricultural Station of the Federal Rural University of Pernambuco, in Carpina County, PE/Brazil. The experimental set was a complete randomized block design, with four replications. The accumulation of nutrients in the components of the aerial part was evaluated at 120; 180; 240; 300 and 360 days after plant (DAP). It was observed along the cycle of the sugar cane, mobilization of nutrients N, P and K from the leaves to the points and stems. At 360 DAP the accumulation of N, P and K in the aerial part was higher than the amount added by fertilizers. The varieties RB92579 and SP81-3250 were detached by the highest nutrients accumulation in stems, while RB867515 and RB943365 were the varieties that allocated more nutrients in leaf, which identifies them as the varieties of larger capacity of cycling of those nutrients.

Adsorption and chemical extraction of phosphorus as a function of soil incubation time

The objectives of this work were to evaluate the relationship between phosphate adsorption in different mineral soil constituents of the clay fraction to determine the P recovery rate by the Mehlich-1, Mehlich-3, Bray-1 and CaCl2 0.01 mol L-1 extractants as a function of incubation time of soil as well as to compare this rate with physical and chemical soil characteristics. In five soil samples five doses of P based on the maximum phosphate adsorption capacities (MPAC) of the soil, were applied, corresponding to 0, 0.2, 0.4, 0.8 and 1.0 level. The samples were incubated for 90, 60, 30, 15 and 0.5 days. The experiment consisted of a 5 x 4 x 5 factorial (five doses, four extractants and five different periods of incubation time) in five different soils, all distributed in blocks, with three replicates. The P content in soil was determined by the Mehlich-1, Mehlich-3, Bray-1 and CaCl2 0.01 mol L-1 extractants. The soil characteristics that best correlated with the recovery rate of applied P were the remaining P (rem-P) and the MPAC. Soils high in gibbsite presented the highest P adsorption. Soils possessing high MPAC and the low rem-P presented higher reversibility for the non-labile P (residual P) for smaller time periods.

Crescimento de meloeiro e acúmulo de nutrientes na planta sob irrigação com águas salinas

This study was conducted in a greenhouse at the Environmental Sciences Department of the Federal Rural University for the Semi-Arid. Four soil types, traditionally used for cantaloupe production in the Mossoro Region, were used and irrigated with solutions corresponding to eight electrical conductivities (EC = 100; 250; 500; 750; 1,250; 1,750; 2,250 and 3,000 µS cm-1) and two sodium adsorption ratios [SAR = 4 and 12 (mmol L-1)1/2], combined as salinity treatments. The experiment was a factorial arrangement of 4 x 8 x 2 (four soils, eight EC and two SAR), with three replicates, and 192 experimental units, in a randomized block design. Plant characteristics (fresh and dry matter production and mineral composition) were evaluated. Fresh and dry cantaloupe production was reduced with increased water salinity in two successive crops, leading to plant death a few days after transplanting in the second cycle. Increased water salinity elevated Ca, Mg, Na, K and Cl accumulation in the plants. Saline water use increased salinity and sodicity of all studied soils, diminishing cantaloupe growth.

Condicionadores químicos e orgânicos na recuperação de solo salino-sódico em casa de vegetação

The salinization is degrading Brazilian semi-arid soils, which need to be reclaimed for agricultural utilization. This work aimed to evaluate use of organic and chemical amendments in a Fluvic Entisol having saline-sodic properties in Pernambucos semi-arid region. Soil experiment was conducted in soil columns, with 10 treatments: sheep manure, cow manure, gypsum, synthetic polymer in six concentrations and the control, in randomized block design. The columns were submitted to leaching during 70 days, being analyzed the leachates collected at 7 and 70 days and the soil after leaching. In leachates, the pH, EC and concentration of Na+, K+ and Cl- were determined; in the saturation extract, pH and EC were measured, and Na+ concentration in saturation extract, and exchangeable Na+ and cation exchange capacity (CEC) were determined to calculate exchangeable sodium percentage (ESP). Soil physico-hydric variables were also determined. The data obtained were submitted to variance analysis and to Scott Knott test at 0,05 level of probability. The treatments, especially manures, gypsum and polymer at smaller concentration decreased EC, ESP and soluble Na+, increasing hydraulic conductivity of the soil.

Fator capacidade de fósforo em solos de pernambuco mineralogicamente diferentes e influência do pH na capacidade máxima de adsorção

O Fator Capacidade de Fosforo (FCP) e definido pela razao de equilibrio entre o fator quantidade de P (Q) e o fator intensidade (I) e representa uma medida da capacidade do solo em manter um determinado nivel de P em solucao. As caracteristicas e o teor dos constituintes minerais da fracao argila sao responsaveis por uma maior ou menor FCP, interferindo nas relacoes solo-planta. Por outro lado, o pH do solo tem, em alguns casos, mostrado-se com efeito na adsorcao e, em outros, com pequena e nao consistente alteracao na Capacidade Maxima de Adsorcao de P (CMAP). Objetivou-se, neste trabalho, determinar o FCP de solos mineralogicamente diferentes em Pernambuco; correlacionar caracteristicas fisicas e quimicas dos solos com o FCP; e avaliar o efeito do pH na CMAP. Amostras subsuperficiais de quatro solos, mineralogicamente diferentes, foram caracterizadas quimica e fisicamente e determinado o FCP. Essas amostras foram corrigidas com CaCO3 e MgCO3 na proporcao 4:1 e incubadas por 30 dias, com excecao do Vertissolo. Determinou-se a CMAP antes e apos a correcao dos solos. O experimento consistiu de um fatorial 4 x 2 (quatro solos com e sem correcao), distribuidos em blocos ao acaso, com tres repeticoes. As caracteristicas dos solos que melhor refletiram o FCP foram o P remanescente (P-rem) e a CMAP. Independentemente dos constituintes mineralogicos da fracao argila, solos com elevados teores de aluminio apresentaram aumento da CMAP com a correcao. A energia de adsorcao (EA) nos solos corrigidos foi, em media, significativamente menor, independentemente do solo.

Características agroindustriais da cana-de-açúcar em função da adubação fosfatada, em solos de Pernambuco

The P recommendations in Northeastern Brazil are based on research carried out in the decades of 70 and 80, being necessary a modernization in this recommendation, to focus the maximum capacity of P adsorption. Therefore, this work aimed to evaluate agroindustrial sugarcane characteristics in soils in function of phosphate fertilization. Five experiments were carried out at Pernambuco State Forest Zone Region. The soils were: Argisoil Yellow distrocoeso (PAdx); Latosoil Yellow distrofic (LAd); Argisoil Yellow distrofic (PAd); Gleisoil haplic eutrofic (GXve); and Espodosoil carbic duripanic (ESKo). The treatments consisted of seven P doses, determined in function of the maximum adsorption capacity of P. The experimental design was a completely randomized block, with four replications. The sugarcane variety RB863129 was used in PAd, LAd, GXve and EKo soils and RB855536 on PAd soil. The P fertilization increased agricultural and industrial productivities. Total recoverable sugar (ATR) values were not affected by phosphate fertilizer, being more elevated in soils with higher maximum adsorption capacity of P.

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.