Industrial saline wastewater in a corn-soybean rotation to enhance crop yield without compromising soil health in a subtropical soil.

The production of industrial waste has increased in the last decades along with world population. Wastes are used in agriculture as fertilizers and soil amendments depending on their composition, dynamics in soil and effects on plant growth. The aim of this study was to assess the effect of industrial saline wastewater from heparin production on soil chemistry and plant yield in a subtropical soil in Brazil. Five rates of industrial saline wastewater (0, 10, 20, 40 and 60 m3 ha-1 year-1) were applied as fertilizer in a corn -soybean rotation on an Oxisol with limited nutrient availability. Five soils sampling were done: before and after the first application of the industrial wastewater (2017, corn), before and after the second application of wastewater (2018, soybean) and two years after the first application (2019). Soil K, Ca, Mg, Na content and CEC increased immediately after the application of wastewater but they returned to former values with time due to plant uptake and lixiviation. Wastewater application significantly increased corn (all rates) and soybean (only with the highest rate) yields around 103-250% and 50%, respectively, in comparison with no wastewater application. However, the highest rate temporally increased soil Na content and electrical conductivity (up to 650 and 800%, respectively). Although nutrient uptake, chlorophyll content and corn and soybean yields were enhanced, the use of high rates of industrial saline wastewater could cause soil salinization (mainly in locations with low rainfall), affecting soil chemistry and physical parameters due to clay dispersion, and pollution or water bodies.

Pedogenic iron oxides in soils of the Acre State, Brazil / Óxidos de ferro pedogênicos em solos do estado do Acre, Brasil

ABSTRACT: Iron oxides are environmental indicators and influence on physical and chemical behavior of soils. This research aimed to identify and characterize pedogenic iron oxides in soils of the Acre state, Brazil. The soils developed from sedimentary rocks of the Solimões Formation. Twenty one samples of subsurface horizons were collected from ten soil profiles. Soil samples were analyzed by x-ray diffractometry associated to selective chemical dissolutions. Fe contents in the clay minerals (Fes), in the pedogenic iron oxides (Fed) and in the poorly crystalline oxides (Feo) were determined. The Al3+-substitution and the mean crystal diameter of goethite and hematite were estimated. Soils presented low contents of Fes and Fed. The Fed/Fes ratio indicated soils in the intermediate stage of weathering, with dominance of goethite, hematite and maghemite. This condition of weathering was confirmed by the higher frequency of goethites and hematite with intermediate Al3+-substitution. Goethites have isodimensional forms and hematite have flat plaques forms.

RESUMO: Os óxidos de ferro são indicadores ambientais e influenciam o comportamento físico e químico dos solos. Este trabalho objetivou identificar e caracterizar os óxidos de ferro pedogênicos de solos do estado do Acre, desenvolvidos de rochas sedimentares da Formação Solimões. Vinte e uma amostras de horizontes subsuperficiais de dez perfis de solos foram analisadas por difratometria de raios x associada a dissoluções químicas seletivas. Os teores de Fe total (Fes), dos óxidos de Fe pedogênicos (Fed) e de baixa cristalinidade (Feo) foram determinados; e a Al3+-substituição e o diâmetro médio cristalino da goethita e da hematita foram estimados. Em geral, os solos apresentaram baixos teores de Fes e de Fed. A relação Fed/Fes indicou solos em estágio de intemperização intermediário, com dominância dos óxidos de Fe goethita, hematita e maghemita. Essa condição de intemperismo foi reforçada pela maior frequência de goethitas e hematitas com intermediária Al3+-substituição. As goethitas possuem formas isodimencionais e as hematitas ocorrem como placas achatadas.

Chromium Displacement in Subtropical Soils Fertilized with Hydrolysed Leather: A Laboratory Study.

Prolonged use of biosolids with high metal content may result in diffuse pollution across large regions, especially if such ions can move freely through the soil profile and reach underground water sources. The objective of this study was to verify whether Cr added to the soil surface in the form of hydrolysed leather or a soluble salt would migrate over significant distances in four subtropical soils differing in physical, chemical and mineralogical properties. Horizontal and vertical mobility were assessed in Petri dishes and small pots, respectively, using low (12 mg kg-1 soil) and high Cr levels (150 mg kg-1 soil) added to the soil surface. Irrespective of concentration, soluble Cr salts were found to move more easily in soils with low organic matter and clay content. Contrarily, Cr added as hydrolysed leather exhibited negligible mobility and tended to accumulate in the vicinity of application.

Óxidos de ferro e área superficial de Latossolo subtropical sob campo e floresta nativa / Iron oxides and specific surface area of the subtropical Oxisol under native pasture and forest

As condições climáticas atuais indicam avanço da vegetação de floresta sobre os campos na região dos Campos de Cima da Serra no Rio Grande do Sul. Essa mudança na vegetação altera o conteúdo de matéria orgânica e a umidade do solo. Este estudo objetivou avaliar os óxidos de ferro pedogênicos em um Latossolo sob campo e floresta nativa e relacionar os mesmos com os teores de carbono orgânico e a área superficial específica do solo. Os teores de carbono orgânico são maiores no solo sob floresta e, possivelmente, influenciaram processos dissolutivos de óxidos de ferro cristalinos e a neoformação de tipos metaestáveis de baixa cristalinidade. O incremento de C orgânico no solo sob floresta elevou expressivamente a área superficial específica do solo, mascarando o efeito geralmente positivo dos óxidos de Fe sobre essa característica física.

The current weather conditions indicate a substitution of grassland by forest vegetation in the Campos de Cima da Serra in Rio Grande do Sul, Brazil. This change in vegetation changes the contents of soil organic matter and soil moisture. This study aimed to evaluate the pedogenetic iron oxides in an Oxisol under native forest and grassland and its relationship with soil total organic carbon content and soil specific surface area. Replacing grassland with native forest resulted in an accumulation of soil organic carbon and possibly influenced dissolutive processes of crystalline iron oxides types and neoformation of metastable types of low crystallinity. In native forest soil, the increase of total organic carbon increased the soil specific surface area, masking the positive effect of iron oxides on this physical characteristic.

Caracterização de plintitas e petroplintitas em solos da depressão central do Rio Grande do Sul / Plintites and petroplintites characterization in soils from central depression of the Rio Grande do Sul state, Brazil

A presença, composição e distribuição de concreções ferruginosas no solo, denominadas de plintitas e petroplintitas, é condicionada às características ambientais da região, atribuindo propriedades intrínsecas ao solo. O objetivo do estudo foi caracterizar plintitas e petroplintitas de solos da Depressão Central do Rio Grande do Sul através da avaliação de características químicas e mineralógicas dessas feições. Para tanto, procedeu-se à caracterização química, morfológica e granulométrica de três perfis de solo. As concreções ferruginosas presentes em alguns horizontes foram separadas da matriz do solo e submetidas, separadamente, a sucessivos procedimentos de extrações seletivas de Fe e Al. Os horizontes dos solos apresentaram ampla variação de textura e atributos químicos como pH, S, V, m e Matéria Orgânica. Os teores de Feh, Fed e Feo seguiram a tendência: matriz do solo

The presence, composition and distribution of ferruginous concretions in the soil, called plinthite and petroplinthites, are conditioned to the environmental characteristics of the region, attributing intrinsic properties to the soil. The objective of this study was to understand the composition of plinthite and petroplinthites, of soils at the Central Depression of Rio Grande do Sul state, Brazil, by the evaluation of chemical and mineralogical characteristics of these features. For this, chemical, morphological and particle size characterization of three soil profiles, was performed. The ferruginous concretions present in some horizons were separated from the soil matrix and submitted, separately to successive procedures for selective extraction of Fe and Al. The horizons of the soils showed a wide variation of textures and chemical attributes such as pH, S, V, m and MO. The levels of Feh, Feo and Fed followed the trend of the soil matrix

Atributos químicos e área superficial específica em Latossolo subtropical de altitude sob usos e manejos distintos / Chemical attributes and specific surface area in highland subtropical Oxisol under different use and managements

A interferência antrópica tem modificado a condição original do solo nos Campos de Cima da Serra. O estudo avaliou atributos químicos e físicos de um Latossolo sob campo nativo (CN), campo nativo manejado com queima (CNq), mata nativa (MN), florestamento de pinus (FP) e lavoura em sistema plantio convencional (LA), nas camadas de 0,00-0,025, 0,025-0,05, 0,05-0,10, 0,10-0,20, 0,20-0,30m. A mineralogia foi avaliada por difratometria de raios X. Foram avaliados o C orgânico total (COT), pH (H2O); Ca, Mg, K, Na e Al trocáveis; H+Al e P; e calculou-se a soma de bases, a capacidade de troca de cátions, a saturação por bases e por Al. Estimou-se a área superficial específica (ASE) e a capacidade máxima de adsorção de fósforo (CMAP). O solo apresentou mineralogia caulinítica e oxídica. No CN, o COT variou entre 15,3 e 56,4g kg-1, o pH foi ≤4,8, a CTC foi alta (18

The original landscape of Campos de Cima da Serra region has changed by anthropogenic interference. The study aimed to evaluate soil chemical and physical attributes of an Oxisol under natural grassland (CN), burned natural grassland (CNq), natural forest (MN), pine afforestation (PF) and annual crops in conventional tillage system (LA), in the 0.00-0.025, 0.025-0.05, 0.05-0.10, 0.10-0.20, 0.20-0.30m layers. The mineralogy was evaluated by X-ray diffraction. It was evaluated the total organic carbon (TOC); pH (H2O); exchangeable Ca, Mg, K, Na and Al; H+Al and P contents; and calculated bases sum (S), cation exchange capacity (CEC) and bases and Al saturation on CEC. It was estimated soil specific surface area (SSA) and maximum phosphorus adsorption capacity (MPAC). The soil showed kaolinitic and oxidic mineralogy. In the CN soil TOC content ranged between 15.3 and 56.4g kg-1, pH values ≤4.8; CEC was high (18