The purpose of this study was to represent the soil moisture in the profile corresponding to the root zone from TDR sensors in a preserved area of the Caatinga biome and analyze the spatialized moisture adjustment equations under different layers of the soil profile. For that, we analyzed three classes of soil (red yellow Ultisol; Hypochromic Luvisol; Udorthent) in the Aiuaba Experimental Watershed, located in the semiarid zone of northeastern Brazil. The hydro-physical parameters representing the soil water retention (field capacity, wilting point and residual moisture) were collected in four campaigns, in six points and in the profiles corresponding to the effective root depth, totaling 216 samples. For the evaluation of the regression models, we used the coefficient of determination, the Pearson correlation and the performance index. The results indicate that the analyzed parameters are homogeneous for the studied soil profiles. The Pearson correlation coefficient indicates a moderate performance for all regression equations. However, the confidence index was determined as very bad for the Red-Yellow Ultisol, passable for the Hypochromic Luvisol and bad for the Udorthent, for the rainy season, and very bad for all classes, for the dry season. Therefore, the use of the regression models is more indicated for periods of higher soil moisture

Tem-se como objetivo analisar a influência da sazonalidade climática da qualidade das águas subterrâneas no Perímetro Irrigado do Baixo Acaraú - CE. Para isso, foram realizadas análises hidroquímicas dos atributos de HCO3-, Ca2+, Cl-, CE, Mg2+, K+, pH, RAS, Na+, SDT, SO42- nos meses de junho e novembro de 2015 e 2016. Realizou-se a análise de agrupamento pelo software SPSS 16.0, onde as médias dos grupos foram comparadas pelo teste T ao nível de 5% de significância e apresentadas em forma de “boxplot”. Na classificação das águas, aplicou-se o Diagrama de Piper e para irrigação a metodologia do Laboratório de Salinidade dos Estados Unidos, pelo software QUALIGRAF. A sazonalidade não influenciou na formação dos grupos. Ocorreu a formação de 2 grupos, onde o grupo 2, apresentou altos valores de sódio. Os altos teores de cloreto do grupo 2 são decorrentes, em sua maioria, da lixiviação de fertilizantes agrícolas. A relação de adsorção de sódio (RAS) elevada no grupo 2, pode reduzir a velocidade de infiltração do solo. Na classificação das águas ocorreu predominância da classe sódica-cloretada. Para irrigação foi observada uma predominância das classes C2S1 e C3S1.

Intense soil preparation and disturbance in crops, over time, reduces the quantity and quality of soil organic matter. Given this context, this work aimed to determine soil carbon stocks and labile fractions under agroforestry system (AFS) and toposequences in an altitude marsh, Taquaritinga do Norte, Pernambuco, Brazil. The study was carried out at the Yaguara farm, and the areas studied were native forest with 4.57 ha and coffee plantation in shade with native forest with 25.59 ha. Soil samples were collected in four trenches measuring 1.5 x 1.5 x 0.60 m, with a distance of 50 meters. Soils were collected at depths of 0–20, 20–40 and 40-60 cm, followed by chemical, physical and density analyzes to determine soil carbon stocks and labile fractions. The area with shaded coffee showed higher values ​​of soil carbon stocks at depths of 0-20 cm and 20-40 cm. At a depth of 40-60 cm, the AFS top toposequence showed the highest carbon stock with 11.73 Mg ha-1, followed by the area with native vegetation with 10.6 Mg ha-1, slope with 9.23 Mg ha-1 and pediment with 7.00 Mg ha-1. It was found that the top toposequence with shaded coffee exhibited a greater stock of labile carbon at depth 0-20 cm with a value of 1.06 Mg ha-1, followed by the bedding areas (SAF) with 0.88 Mg ha-1, native forest with 0.79 Mg ha-1 and slope with 0.67 g kg-1. However, the area of native vegetation showed the highest value of labile carbon at a depth of 40-60 cm. It was concluded that the area with shaded coffee in the top toposequence showed great capacity to increase total carbon stocks and labile carbon stocks of soil organic matter.

Lâminas de irrigação e frequência de aplicação no crescimento do meloeiro. DOI: 10.7127/rbai.v7n100102