Navegando por Autor "Ramos, Bárbara Zini"

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Doses de gesso em cafeeiro: influência nos teores de cálcio, magnésio, potássio e ph na solução de um latossolo vermelho distrófico
(Sociedade Brasileira de Ciência do Solo, 2013-08-24) Ramos, Bárbara Zini; Toledo, João Paulo Vaz Floriano; Lima, José Maria de; Serafim, Milson Evaldo; Bastos, Ana Rosa Ribeiro; Guimarães, Paulo Tácito Gontijo; Coscione, Aline Renée
Unbalanced amounts of Ca2+, Mg2+ and K+ in soils as a consequence of high gypsum applications can be due to the relationship in size (ionic radius) and charge density (charge/ ionic radius) of each ionic species. The higher the ionic strength, the stronger is the bonding of these cations with the opposite charge ions such as OH- , SO4 -2. Thus, excessive gypsum applications, disregarding the charge balance of the soil colloidal system, the ionic balance of the solution, and the CEC, can result in significant leaching of these nutrients throughout the soil profile. The aim of this study was to evaluate the effect of high gypsum rates (0, 7, and 56 t ha-1) on the pH and Ca2+, Mg2+, and K+ contents in aqueous soil extracts of a dystrophic Red Latosol with coffee. The soil was sampled in the coffee rows in the following depths: 0.15- 0.25; 0.35-0.45; 0.75-0.85; 1.15-1.25, and 2.35-2.45 m, 16 months after gypsum application. The experiment consisted of four treatments: G-0 – 2 t ha-1 of gypsum was applied in total área during soil preparation, with brachiaria between coffee rows; G-7 - same as in G-0 plus 7.0 t ha-1 of gypsum applied to the coffee rows; G-56 – same as in G-0 plus 56 t ha-1 of gypsum applied to the coffee rows; and CV-7 - same as in G-7 but without brachiaria between the coffee rows. The experiments were conducted in triplicate, in a randomized block design. After 16 months, there was a reduction of the pH of the soil solution in the layers 0.15-0.25, 0.35-0.45, and 0.75-0.85 m. Gypsum improved the root environment in deeper layers, increasing Mg2+ and Ca2+ concentrations in the soil solution, but reduced K+ below 0.85 m. The amounts of exchangeable Ca2+ and Mg2+ found in the soil solution were above the critical level while exchangeable K+ was within the range indicated for the crop.
Doses de gesso em cafeeiro: influência nos teores de cálcio, magnésio, potássio e ph na solução de um latossolo vermelho distrófico
(Sociedade Brasileira de Ciência do Solo, 2013-07) Ramos, Bárbara Zini; Toledo, João Paulo Vaz Floriano; Lima, José Maria de; Serafim, Milson Evaldo; Bastos, Ana Rosa Ribeiro; Guimarães, Paulo Tácito Gontijo; Coscione, Aline Renée
O desbalanço entre Ca 2+ , Mg 2+ e K + no solo como consequência das aplicações elevadas de gesso deve-se às relações de tamanho (raio iônico) e densidades de cargas (relação carga/raio) de cada espécie iônica. Quanto maior a densidade de carga, mais intensa será a ligação iônica do cátion com íons de cargas opostas como OH - e SO 4-2 . Dessa maneira, o uso excessivo de gesso agrícola, sem considerar o balanço de cargas das partículas do solo; o equilíbrio iônico; e a CTC podem resultar em expressiva lixiviação ao longo do perfil do solo. O objetivo deste estudo foi avaliar o efeito de elevadas doses de gesso (0, 7 e 56 t ha -1 ) nos teores de Ca 2+ , Mg 2+ , K + e pH na solução de um Latossolo Vermelho distrófico cultivado com cafeeiro, obtida pelo método adaptado do extrato aquoso. O solo foi amostrado nas profundidades de 0,15-0,25; 0,35-0,45; 0,75-0,85; 1,15-1,25 e 2,35-2,45 m na linha de plantio, em quatro tratamentos: G-0 - gesso no preparo (aplicação ocorreu em setembro de 2008, distribuído a lanço, na quantidade de 2 t ha -1 ) e sem gesso na linha de plantio; G-7 - gesso adicionado durante a preparação do solo (2 t ha -1 ), na mesma condição do G-0 e 7,0 t ha -1 de gesso na linha de plantio; G-56 - gesso adicionado durante a preparação do solo (2 t ha -1 ), na mesma condição do G-0 e 56 t ha -1 de gesso na linha de plantio (nessas parcelas experimentais as entrelinhas de plantio foram cobertas com braquiária); e CV-7: ausência de braquiária na entrelinha, com gesso no preparo e 7 t ha -1 de gesso na linha, com três repetições distribuídas em blocos ao acaso, totalizando 60 amostras. Após 16 meses da adição de gesso, observou-se redução do pH na solução do solo nas profundidades de 0,15- 0,25; 0,35-0,45 e 0,75-0,85 m. A aplicação de gesso agrícola foi eficiente na melhoria do ambiente radicular no subsolo, aumentou a concentração de Mg 2+ e Ca 2+ na solução do solo, mas reduziu o K + em profundidade, a partir de 0,85 m. Os teores de Ca 2+ e Mg 2+ trocáveis na solução do solo estiveram acima do nível crítico; entretanto, os teores de K + trocável se mantiveram na faixa do valor crítico, indicado para o desenvolvimento da cultura.
Ionic speciation in a dystrophic red latosol under coffee crop high doses of gypsum
(Editora UFLA, 2019-07-03) Ramos, Bárbara Zini; Lima, José Maria de; Serafim, Milson Evaldo; Coscione, Aline Renée; Ferraz, Raul Magalhães; Amorim, Lucas Mota; Lopes, Guilherme
The cultivation of coffe crops in Brazil, especially on Latosols, has been increasing over the years, despite limitations such as aluminum toxicity, low fertility and very long drought periods. In this scenario, soil amendments to mitigate these restraints are necessary. Since these limitations are not restricted to the arable layer, application of gypsum becomes an efficient alternative to sustain soil fertility and deepen the root system to get water from the deeper layers of soil. However, high doses of gypsum can cause unbalance among Ca 2+ , Mg 2+ and K + . The objective of this work was to evaluate these bases as well as their ionic pairs, and the presence of sulfate along the soil profile 16 months after the application of high gypsum doses in a Latosol under coffee crops. An inicial dose of gypsum was applied in the entire area, followed by four treatments, in triplicate and randomized blocks, set as follows: G0 - zero gypsum applied over the planting line after the initial soil preparation; G7- 7 t ha -1 of gypsum in the planting line (1.75 kg m -1 ); G56 - 56 t ha -1 of gypsum in the planting line (14 kg m -1 ), all with brachiaria between the coffee planting lines; and CV7 - 7 t ha -1 of gypsum in the line and no brachiaria between the planting lines. The soil profile was sampled in layers up to 2.40 m depth and the soil solution was extracted by suctioning the sample-saturated paste. Following this extraction, the soil solution was analyzed by combustion for total carbon contents, ion chromatography and ICP-OES/flame photometry, for chemical species, and speciation was done using Minteq software. After 16 months of gypsum application, 96% of K + in soil solution was at 0.35 to 0.45 m in its free form. Leaching of Ca 2+ and Mg 2+ occurred predominantly in their free forms, although a more significant contribution of CaSO 40 and MgSO 40 ionic pairs was observed when compared to K 2 SO 40.