Chemical and mineralogical changes in a Brazilian Rhodic Paleudult under different land use and managements

Abstract

Changes in land use and management can affect the dynamic equilibrium of soil systems and induce chemical and mineralogical alterations. This study was based on two long-term experiments (10 and 27 years) to evaluate soil used for no-tillage maize cultivation, with and without poultry litter application (NTPL and NTM), and with grazed native pasture fertilized with cattle droppings (GrP), on the chemical and mineralogical characteristics of a Rhodic Paleudult in Southern Brazil, in comparison with the same soil under native grassland (NGr). In the four treatments, soil was sampled from the 0.0-2.5 and 2.5-5.0 cm layers. In the air-dried fine soil (ADFS) fraction (∅ < 2 mm), chemical characteristics of solid and liquid phases and the specific surface area (SSA) were evaluated. The clay fraction (∅ < 0.002 mm) in the 0.0-2.5 cm layer was analyzed by X-ray diffraction (XRD) after treatments for identification and characterization of 2:1 clay minerals. Animal waste application increased the total organic C concentration (COT) and specific surface area (SSA) in the 0.0-2.5 cm layer. In comparison to NGr, poultry litter application (NTPL) increased the concentrations of Ca and CECpH7, while cattle droppings (GrP) increased the P and K concentrations. In the soil solution, the concentration of dissolved organic C was positively related with COT levels. With regard to NGr, the soil use with crops (NTM and NTPL) had practically no effect on the chemical elements in solution. On the other hand, the concentrations of most chemical elements in solution were higher in GrP, especially of Fe, Al and Si. The Fe and Al concentrations in the soil iron oxides were lower, indicating reductive/complexive dissolution of crystalline forms. The X-ray diffraction (XRD) patterns of clay in the GrP environment showed a decrease in intensity and reflection area of the 2:1 clay minerals. This fact, along with the intensified Al and Si activity in soil solution indicate dissolution of clay minerals in soil under cattle-grazed pasture fertilized with animal droppings.

Clay Mineralogy of Subtropical Soils under Long-Term Organic Fertilization in No-Tillage Systems

“…The increase in OM and soil moisture induced no reduction in Fe d contents neither increased the Fe o contents in samples of residue fertilization treatments from the surface layer. Similar observations were reported by Silva Neto et al (2008), Inda et al (2013), and Fink et al (2014). The Zn d and Zn o contents in the clay fraction were higher in the treatments with residue application than in the unfertilized treatment.…”

“…In the two experiments, three soil samples per plot were collected from the layers 0.00-0.04, 0.04-0.08, and 0.16-0.20 m. The sampling layers were determined as suggested in the literature (Inda et al, 2010;Lourenzi et al, 2013;Fink et al, 2014;Lourenzi et al, 2016), which significant changes were observed in the surface layer only (0.00-0.10 m). The 0.16-0.20 m layer was included for comparison.…”

“…Organic fertilization also raises the soil K content, promoting a reduction of smectites and increase in illite/smectite interstratifications (Pernes-Debuyser et al, 2003). Another mechanism cited in the literature is the precipitation of new mineral phases by iron reoxidation, due to the increase of OM and moisture (Liptzin and Silver, 2009;Inda et al, 2013;Fink et al, 2014). In these cases, the data of Fe extracted with DCB and ammonium oxalate evidenced the transformation of hematite and goethite in low-crystalline phases such as ferrihydrite or lepidocrocite.…”

Short-Term Changes in Fertility Attributes and Soil Organic Matter Caused by the Addition of EM Bokashis in Two Tropical Soils

“…The conjunct of these results made clear the fertility capacity of these inputs. Several papers had related the increased soil fertility due to the use of organic residues in Brazilian soils [6,13,14]. In this study, a very heterogeneous behavior was observed with respect to the potential fertility improvement provided by each EM Bokashi for each soil.…”

Adsorption and desorption of phosphorus in subtropical soils as affected by management system and mineralogy

“…Significant differences in Fe d were observed between NT and CT samples by effect of the accumulation of organic matter in the soil surface promoting dissolution reactions of iron oxides (Liptzin and Silver, 2009;Inda et al, 2013;Fink et al, 2014a). Fe in iron oxides of low crystallinity (Fe ox ) ranged from 1.0-3.8 g kg À1 and peaked in the sub-surface layers of RH and HH.…”