Aluminum species and activity in sandy soil solution with pig slurry addition

Abstract

-The objective of this work was to evaluate the effect of pig slurry applications on the exchangeable Al content, activity, and distribution of Al chemical species in the soil solution. Soil samples of a Typic Hapludalf were obtained from an experiment conducted during eight years, with 19 applications of 0, 20, 40, and 80 m 3 ha -1 pig slurry. The soil samples were collected in stratified layers to determine exchangeable Al content and to extract the soil solution by the saturated soil paste method. The concentrations of the main cations and anions, dissolved organic carbon, and pH in the soil solution were determined.

Composition, chemical speciation and activity of ions in the solution of Brazilian acid soils

“…In field conditions, Nolla et al (2013) also observed the formation of Al phosphate by the release of organic acids by soybean plants that are able to complex the Al in the soil solution under conditions of higher acidity. De Conti et al (2017) applied increasing doses of swine manure and also verified the increase of the formation of Al complexed with P due to the increase of the concentration of this element in solution, mainly in the upper layers of the soil evaluated in this study. Zambrosi et al (2008) evaluated the distribution of Al and nutrient species in the solution in a dystrophic Red Latosol after five years of limestone application and also identified the presence of the complex formed between Al and phosphate in the upper layers and concluded that the phosphate ions in the solution are prone to strong interactions with Al, Fe, Ca and Mg.…”

“…This may have occurred because these soils have a high concentration of Al in the solution and the addition of P increases the concentration of phosphate ions (Table 2), favoring the formation of Al-HPO 4 + , (55% in PE and 59% in BR of the total phosphate ions in the solution). The strong interaction of these ions with Al, Fe and Mn is well known and results in decreased availability of P in the solution and also reduced risk of Al toxicity to plants (Rutkowska et al, 2015;De Conti et al, 2017). In a lower proportion, HPO 4 2was found in the same treatments, 0.33% in AC9, 0.12% in PE, 0.75% in RS, 0.2 in BR and 0.3% in CB.…”

“…The low adsorption of these chemical species by the inorganic solids of the soil causes them to be present in greater quantity and in field conditions, they can be leached (Francisco et al, 2016). For Zambrosi et al (2008) andDe Conti et al (2017), the increase of sulfate ions in the solution of the studied soils resulted from the application of limestone and swine manure, respectively.…”

“…These differences in DOC concentrations in the solution can be attributed to the natural total organic carbon (TOC) contents, quantified in the samples collected under natural TOC conditions, and quantified in the samples collected under natural conditions of these soils, with clay amounts and type of clay minerals in the soils. This is because the sorption of organic compounds to the solid phase of the soil, in particular Fe and Al oxides and hydroxides, can decrease DOC concentration in the soil solution (Peralta & Costa, 2013;De Conti et al, 2017).…”

“…Speciation includes free ions, complex ions, ion pairs and chelates in solution. The use of computer softwares such as Minteq A2 algorithm facilitates the production of these forms by rapidly providing estimates of the species and the respective ion activity in the soil solution (Rutkowska et al, 2015;De Conti et al, 2017). They simultaneously consider the various chemical equilibria involved in the reactions responsible for the formation of complexes, and solid dissolution and precipitation, calculating activity coefficients and the distribution of the free species, as well as their complexes and precipitates (Rossiello & Netto, 2006).…”