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1.
Sci. agric ; 79(4): e20200235, 2022. tab, graf
Artigo em Inglês | VETINDEX | ID: biblio-1290211

Resumo

Hydrogels have potential as soil conditioners due to their high capacity to retain water and mitigate soil salinity. However, investigations under saline conditions are necessary because there are losses in both water absorption and salinity mitigation depending on the composition of hydrogel and ions involved in salinity. In this work, we studied a commercial hydrogel in two experiments. The first experiment was conducted in the laboratory to evaluate the absorption by the hydrogel of water with electrical conductivity (EC) of 0.5, 1.5, 3.0, and 4.5 dS m-1, promoted by NaCl. The second experiment was conducted in a greenhouse in a 2 × 4 factorial scheme (with and without hydrogel × EC of the first experiment). Although salinity reduced water absorption by hydrogel by 84 %, the polymer applied in a sandy soil under saline conditions reduced water losses by 58 %. However, hydrogel did not increase the final soil moisture (~ 0.10 g g-1). The polymer reduced Na+ concentration in leachate from 1,499 to 1,219 mg L-1 at the highest salinity level (4.5 dS m-1), but it increased Na+ soil availability by 0.1 mg kg-1 in comparison with polymer absence. Hydrogel application increased Na+ content in plants from 9 to 13 mg kg-1 at the highest salinity, while K+ content was 10 to 16 mg kg-1 lower than that observed without a polymer. Hydrogel 0.07 % (w/w) reduced maize biomass, indicating damage by monovalent ions, compromising the polymer potential under salinity.


Assuntos
Água , Solos Salitrosos/análise , Hidrogéis/análise , Salinidade , Acrilatos , Acrilamida/análise
2.
Acta amaz ; 40(1): 23-30, mar. 2010. tab, graf
Artigo em Português | LILACS, VETINDEX | ID: lil-546953

Resumo

O objetivo do estudo foi avaliar os efeitos de plantios de Acacia mangium, localizados no cerrado em Roraima, sobre o carbono orgânico e biomassa microbiana do solo. Foram realizadas amostragens de solo nas profundidades de 0-20 cm e 20-40 cm em dois plantios de A. mangium com cerca de cinco anos de idade, e em duas áreas de Cerrado nativo consideradas referência. Um dos plantios de A. mangium (localizado na Fazenda Cigolina) correspondeu a um plantio homogêneo (espaçamento de 3,6 m entre linhas e 2,0 m entre plantas) enquanto que o outro (localizado no Campo Experimental Água Boa - CEAB) correspondeu a um plantio em faixas com duas linhas de plantio (espaçamento de 6 m entre linhas, 2,5 m entre plantas e cerca de 30 m entre faixas). As amostras de solo foram analisadas quanto ao carbono orgânico, carbono da biomassa microbiana, respiração basal do solo e quociente metabólico, além de atributos químicos de fertilidade. Foi verificado que os plantios de A. mangium não proporcionaram aumentos significativos do carbono orgânico do solo em comparação às áreas de referência. Entretanto, na média geral, esses plantios proporcionaram aumento do carbono da biomassa microbiana do solo e redução do quociente metabólico, indicando a possibilidade de acúmulo de carbono orgânico no solo em longo prazo. Também foi observado que, em comparação ao plantio da fazenda Cigolina e às áreas de referência, o carbono microbiano do solo foi maior e acompanhado de menor quociente metabólico no plantio de A. mangium no CEAB, mostrando que a estrutura de plantio exerceu influência sobre a biomassa microbiana do solo.


The aim of this study was to evaluate the effects of Acacia mangium plantation in the Roraima's Savanna, on soil organic carbon and soil microbial biomass. Soil samplings were collected on the depths of 0-20 cm and 20-40 cm in two Acacia mangium plantation sites, about five years old, and in two sites of native savanna as reference. One of the A. mangium sites (located at Fazenda Cigolina) was composed by a homogeneous plantation (3.6 m between row and 2.0 m between trees) and, the other one (located at Campo Experimental Agua Boa Experimental - CEAB) was composed by a plantation on which the planting distances had strips of two rows 6 meters apart, 2.5 meters between trees and 30 meters between strips). Soil samples were analyzed regarding soil organic carbon, microbial biomass carbon, soil basal respiration and metabolic quotient, besides soil fertility attributes. Results showed that A. mangium plantations did not provide significant increases of organic carbon on the soil comparing with sites used as reference. However, generally, A. mangium plantation increased soil microbial biomass carbon and reduced metabolic quotient, indicating a possibility of soil organic carbon accumulation in long-term. It was also observed that, soil biomass microbial carbon was higher, followed by smaller metabolic quotient at CEAB A. mangium plantation compared with Cigolina and reference sites, showing that planting design exercised influence on soil microbial biomass.


Assuntos
Microbiologia do Solo , 24444 , Qualidade do Solo , Acacia/fisiologia , Biomassa , Ecossistema Amazônico
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