RESUMO A recuperação de solos com elevada salinidade e alcalinidade requer a utilização de produtos que promovam a redução do pH e diminuam os teores de Na trocável, para melhorar a sua fertilidade. Objetivou-se avaliar o efeito do sulfato de cálcio e do enxofre elementar sobre os atributos químicos de um solo com altos teores de sais solúveis e Na trocável. Dois experimentos foram conduzidos em casa-de-vegetação, utilizando-se amostras de um Neossolo Flúvico sódico sálico de textura franco-arenosa. No primeiro experimento, foram testados quatro tratamentos referentes à correção do solo (sem corretivo, sem corretivo e sem lavagem, corrigido com sulfato de cálcio e corrigido com enxofre elementar). No segundo experimento, os tratamentos compreenderam cinco doses de enxofre elementar (0 kg ha-1, 400 kg ha-1, 800 kg ha-1, 1.200 kg ha-1 e 1.600 kg ha-1). O enxofre elementar e o sulfato de cálcio influenciaram positivamente os atributos químicos do solo, proporcionando melhor fertilidade. O enxofre elementar, além de melhorar os atributos químicos desse solo, é mais eficiente que o sulfato de cálcio na diminuição de sua alcalinidade, contudo, o uso desse produto requer a aplicação de fonte adicional de cálcio ao solo. Devido ao seu baixo teor de argila, a simples lavagem contribui para diminuir a salinidade e sodicidade do solo.

It was aimed to evaluate the effect of doses of phosphorus and different doses of bovine manure on growth of melon Galia. The experiment was carried out in greenhouse utilizing pots filled with soil Chromic Luvissoil in design completely randomized with a 5 x 2 factorial arrangement, comprising five doses of bovine manure (0, 12, 16, 20, 24 t ha-1) and two doses of phosphorus (0 and 400 mg dm-3), with three replicates, totaling 30 experimental units. The results indicated that interaction of phosphorus with organic matter was significant effect on total dry mass of the melon plant. There was a reduction of the total dry mass when the plants were fertilized at the highest doses of bovine manure. The P content from leaf and stem increased gradually at higher doses of phosphorus. The phosphorus content in the soil increased according to the doses of organic material available.

Haplic Vertisols and Typic Quartzipsamments are among the main classes of soils used for melon production in the Brazilian semiarid region. Potassium (K) is the nutrient most extracted by yellow melon fruits and, for this reason, high doses of potassium fertilizers are often applied to these soils. This study aimed to evaluate potassium fractions in soils of the Brazilian semiarid region, during the cultivation cycle of fertigated yellow melon. Two experiments were carried out with two types of soil (Haplic Vertisol and Typic Quartzipsamment). For the Vertisol, a 7 x 2 [seven evaluation periods and two soil layers (0-20 cm and 20-40 cm)] factorial arrangement was established, with four replications, totaling 56 experimental units. For the Quartzipsamment, a 9 x 2 [nine collection times and two soil layers (0-20 cm and 20-40 cm)] factorial arrangement was used, with four replications, totaling 72 experimental units. The non-exchangeable K fraction was dominant in both soils, mainly in the 0-20 cm layer, and represents an important reserve of this nutrient for melon cultivation, especially in Haplic Vertisols. The decrease in the concentrations of the soluble and exchangeable forms and the increase in the non-exchangeable form indicated an increase in the fixation of this nutrient, by fixation in the Vertisol and leaching in the Quartzipsamment, at the end of the melon cycle, when the amount of K accumulated by the plant was lower.

Frações de nitrogênio no solo e na fitomassa foliar de berinjela e rúcula sob doses de nitrogênio associadas à extratos de Nim Nitrogen fractions in soil and phytomass of eggplant and arugula under nitrogen doses associated with neem extracts

To evaluate the effect of fertilization with N and Si on gaseous exchanges, dry mass, concentrations, accumulations and compartmentalization of nitrogen fractions in eggplant. The experimental design was a randomized entirely design, in a 5 x 4 factorial arrangement with four replications and one plant per plot, totaling 80 experimental units. The experiment was conducted in a protected environment at Center of Sciences and Agri-Food Technology of the Federal University of Campina Grande, Campus of Pombal, Paraiba, Brazil, between July and September 2016. The nitrogen doses applied was 25, 125, 250, 350 and 500 mg dm-3 and four silicon doses was 0, 75, 150 and 200 mg dm-3 both supplied by root. In pre-flowering stage were evaluated growth components; gas exchange, which are: photosynthesis, stomatal conductance, transpiration rate and intercellular CO2 concentration; levels and accumulation of fractions of nitrogen (NO3-, NH4+, and total), and the silicon concentration in the leaves. There was no significant interaction (p >0.05) between the factors nitrogen and silicon doses for any of the evaluated variables. Nitrogen and silicon doses influenced the variables evaluated only independently each other. The nitrogen doses promoted increases in the photosynthetic rate and associated variables, dry matter yield of stem leaves and roots and in the concentration and accumulations of nitric, ammoniacal and total nitrogen in leaf, stem e roots and decrease the concentration of silicon in leaves. The silicon doses increased the leaf area index, the nitrate levels and accumulation in the roots and the silicon content in the leaves. In conclusion, the nitrogen supply increased the photosynthetic rate, dry mass and nitrogen accumulation and decreased the concentrations of silicon in leaf. Silicon did not interfered with growth of eggplant, however increased leaf area index, decreased nitrate levels and accumulations in the roots at lower doses of this element.