Spatial variability of the stability of cohesive soil aggregates under conservation practices / Variabilidade espacial da estabilidade dos agregados de solo coeso sob práticas conservacionistas

The knowledge and characterization of aggregate stability are relevant to select adequate management and to avoidits degradation. Thus, this studyaimed to characterize the spatial variability of aggregate stability in cohesive soilsunder crop conservation systems. The experiment was performed intwo different areas of soybean production: no-tillage System (NTS) and livestock farming integration system (LFI), In each production area, a sampling mesh composed of 50 collection points, with a regular spacing of 40 m, at 0.00-0.20 mdepth, wascarried out. The results were expressed as a percentage of aggregates retained in sieves 2; 1; 0.5 and 0.25 mm, the values obtained were used to calculate the Mean Geometric Diameter (MGD) and Mean Weight Diameter (MWD). In the LFI system, which had a strong degree of spatial dependence (DSD), the attributes showed a moderate DSD, except for MWD. Generally, the reachedvalues of the attributes in the LFI system were lower than those found in the NTS system, showing less variability in the management system with no-tillage. Spatial distribution of the kriging maps demonstrated the LFI system leading to the formation of larger aggregates in the soil when compared to ones to the same attributes in the NTS. All attributes showed a strong to moderatespatial dependence. The soil managed with the LFI system revealed greater aggregate stability when compared to the NTS, which in turn presented less spatial variability than the LFI system and shows a more homogeneous soil.(AU)

O conhecimento e a caracterização da estabilidade dos agregados são relevantes para selecionar um manejo adequado e evitar sua degradação. Portanto, este estudoteve como objetivo caracterizar a variabilidade espacial da estabilidade de agregados em solos coesos sob sistemas de conservação de culturas. O experimento foi conduzido em duas áreas distintas de produção de soja: sistema de plantio direto (NTS) e sistema de integração pecuária (LFI). Foi realizada uma amostragem de 50 pontos de coleta, com espaçamento regular de 40 m, na profundidade de 0,00-0,20 m, em cada área de produção.Os resultados foram expressos como porcentagem de agregados retidos nas peneiras 2; 1; 0,5 e 0,25 mm, os valores obtidos foram utilizados para calcular o Diâmetro Médio Geométrico (DMM) e o Diâmetro Peso Médio (DMM). No sistema LFI, que possuía alto grau de dependência espacial (DDS), os atributos apresentaram um DSD moderado, exceto para MWD. De maneira geral, os valores de escopo dos atributos no sistema LFI foram inferiores aos encontrados no sistema NTS, apresentando menor variabilidade no sistema de manejo do plantio direto. A distribuição espacial dos mapas de krigagem mostrou que o sistema LFI leva à formação de agregados maiores no solo em comparação com outros com os mesmos atributos no NTS. Todos os atributos apresentaram dependência espacial de forte a moderada. O solo manejado com o sistema LFI revelou maior estabilidade dos agregados em relação ao NTS, que por sua vez apresentou menor variabilidade espacial do que o sistema LFI e apresenta um solo mais homogêneo.(AU)

Soil quality indicators under management systems in a Quilombola community in the Brazilian Cerrado

Soil management systems exert different effects on soil attributes, especially on the organic matter content, and, consequently, the soil aggregation. The aim of this study was to evaluate the impact of different land uses practiced by quilombola family farmers on water stable aggregates, glomalin and organic carbon in soil aggregates. Soil samples were collected at depths of 0-10 and 10-20 cm from areas cultivated under the following management systems: 1) conventional corn plantation (MA), 2) cultivation of citrus trees intercropped with annual crops (AC) (a conservationist approach), 3) pasture of Brachiaria (Urochloa spp.) (PA), and, as reference, an area of the Cerrado (CR) free of any anthropogenic interference. The studied areas were evaluated in a completely randomized design, with five replications, in a subplot scheme. The plots were the management systems and the subplots the depths. Soil macro-aggregates were predominant at both depths and the aggregate stability indices were higher than 90 % for all management systems. Total organic carbon in the two aggregate classes (micro and macro-aggregates) correlated with the MWD (mean weight-diameter), but not with the easily extractable glomalin (EEG) related soil protein. Soil micro and macro-aggregates, EEG and MWD discriminated management systems and are important soil quality indicators. The carbon content in both micro-aggregates (C-MIC) and macro-aggregates (C-MAC) of the intercropped system (AC) was higher than in the CR. The soil attributes that best separated the areas were C-MIC, MWD and EEG in macro-aggregates for the depth of 0-10 cm, and EEG in micro-aggregates, together with MWD and C-MAC for the depth of 10-20 cm.

Soil quality indicators under management systems in a Quilombola community in the Brazilian Cerrado

Soil management systems exert different effects on soil attributes, especially on the organic matter content, and, consequently, the soil aggregation. The aim of this study was to evaluate the impact of different land uses practiced by quilombola family farmers on water stable aggregates, glomalin and organic carbon in soil aggregates. Soil samples were collected at depths of 0-10 and 10-20 cm from areas cultivated under the following management systems: 1) conventional corn plantation (MA), 2) cultivation of citrus trees intercropped with annual crops (AC) (a conservationist approach), 3) pasture of Brachiaria (Urochloa spp.) (PA), and, as reference, an area of the Cerrado (CR) free of any anthropogenic interference. The studied areas were evaluated in a completely randomized design, with five replications, in a subplot scheme. The plots were the management systems and the subplots the depths. Soil macro-aggregates were predominant at both depths and the aggregate stability indices were higher than 90 % for all management systems. Total organic carbon in the two aggregate classes (micro and macro-aggregates) correlated with the MWD (mean weight-diameter), but not with the easily extractable glomalin (EEG) related soil protein. Soil micro and macro-aggregates, EEG and MWD discriminated management systems and are important soil quality indicators. The carbon content in both micro-aggregates (C-MIC) and macro-aggregates (C-MAC) of the intercropped system (AC) was higher than in the CR. The soil attributes that best separated the areas were C-MIC, MWD and EEG in macro-aggregates for the depth of 0-10 cm, and EEG in micro-aggregates, together with MWD and C-MAC for the depth of 10-20 cm.(AU)

Crop-livestock integration and the physical resilience of a degraded Latosol / Integração agricultura-pecuária e resiliência física de um Latossolo degradado

The degradation of pastures in Brazil is a problem of agronomic and environmental importance because it impairs the productive capacity of the soil and the hydrological cycle. In this context, the integration of agriculture and livestock emerges as a promising practice in recovering degraded soils through aggregation, increasing organic carbon in the soil and breaking compacted layers via the growth of grass roots. This study aimed to evaluate suitable indicators of physical quality in regard to mitigating structural changes of a Latosol cultivated with different species of the genus Brachiaria. We evaluated the grasses Brachiaria brizantha (Xaraés, Piatã, Marandu), Brachiaria decumbens and Brachiaria ruziziensis and adopted fallow and conventional tillage as controls. Soil samples were used to evaluate the parameters total organic carbon, soil aggregation via wet sieving and the least limiting water range (LLWR). Total organic carbon and aggregate stability were not suitable indicators for quantifying soil structural changes, remaining high in the evaluated conservation systems, with a difference observed only in the control with conventional tillage. The LLWR varied among all systems and layers evaluated. Xaraés palisadegrass, followed by the Piatã and Marandu cultivars, stood out in terms of biological soil loosening ability, being similar to the recovery caused by soil tillage. Furthermore, B. decumbens showed intermediate performance, while B. ruziziensis showed activity similar to that in the fallow treatment, indicating limited potential for soil physical recovery.

A degradação das pastagens no Brasil é um problema de ordem agronômica e ambiental, pois compromete a capacidade produtiva do solo e o ciclo hidrológico. Neste contexto, a integração agricultura-pecuária surge como uma prática promissora na recuperação de solos degradados, através da agregação, aumento dos estoques de carbono no solo e do rompimento de camadas compactadas pelo crescimento radicular das gramíneas. Este trabalho objetivou avaliar o indicador adequado de qualidade física na mitigação da compactação de um Latossolo cultivado com espécies do gênero Brachiaria. Foram avaliadas as gramíneas: Brachiaria brizantha (Xaraés, Piatã, Marandu); Brachiaria decumbens e Brachiaria ruziziensis. Adotou-se como controle: pousio e cultivo convencional. Amostras de solo foram utilizadas para avaliar o carbono orgânico total, a agregação do solo via peneiramento úmido e o intervalo hídrico ótimo (IHO). O carbono orgânico e a estabilidade dos agregados não foram indicadores adequados para quantificação das alterações estruturais do solo, permanecendo alta nos sistemas de conservação avaliados e diferindo apenas do controle com preparo convencional. O IHO variou entre todos os sistemas e camadas avaliadas. O capim Xaraés, seguido por Piatã e Marandu, destacou-se na escarificação biológica do solo, similarmente à recuperação via preparo do solo, e B. decumbens apresentou desempenho intermediário, enquanto B. ruziziensis apresentou atividade semelhante ao pousio, indicando potencial limitado de recuperação física do solo.

Crop-livestock integration and the physical resilience of a degraded Latosol / Integração agricultura-pecuária e resiliência física de um Latossolo degradado

The degradation of pastures in Brazil is a problem of agronomic and environmental importance because it impairs the productive capacity of the soil and the hydrological cycle. In this context, the integration of agriculture and livestock emerges as a promising practice in recovering degraded soils through aggregation, increasing organic carbon in the soil and breaking compacted layers via the growth of grass roots. This study aimed to evaluate suitable indicators of physical quality in regard to mitigating structural changes of a Latosol cultivated with different species of the genus Brachiaria. We evaluated the grasses Brachiaria brizantha (Xaraés, Piatã, Marandu), Brachiaria decumbens and Brachiaria ruziziensis and adopted fallow and conventional tillage as controls. Soil samples were used to evaluate the parameters total organic carbon, soil aggregation via wet sieving and the least limiting water range (LLWR). Total organic carbon and aggregate stability were not suitable indicators for quantifying soil structural changes, remaining high in the evaluated conservation systems, with a difference observed only in the control with conventional tillage. The LLWR varied among all systems and layers evaluated. Xaraés palisadegrass, followed by the Piatã and Marandu cultivars, stood out in terms of biological soil loosening ability, being similar to the recovery caused by soil tillage. Furthermore, B. decumbens showed intermediate performance, while B. ruziziensis showed activity similar to that in the fallow treatment, indicating limited potential for soil physical recovery.(AU)

A degradação das pastagens no Brasil é um problema de ordem agronômica e ambiental, pois compromete a capacidade produtiva do solo e o ciclo hidrológico. Neste contexto, a integração agricultura-pecuária surge como uma prática promissora na recuperação de solos degradados, através da agregação, aumento dos estoques de carbono no solo e do rompimento de camadas compactadas pelo crescimento radicular das gramíneas. Este trabalho objetivou avaliar o indicador adequado de qualidade física na mitigação da compactação de um Latossolo cultivado com espécies do gênero Brachiaria. Foram avaliadas as gramíneas: Brachiaria brizantha (Xaraés, Piatã, Marandu); Brachiaria decumbens e Brachiaria ruziziensis. Adotou-se como controle: pousio e cultivo convencional. Amostras de solo foram utilizadas para avaliar o carbono orgânico total, a agregação do solo via peneiramento úmido e o intervalo hídrico ótimo (IHO). O carbono orgânico e a estabilidade dos agregados não foram indicadores adequados para quantificação das alterações estruturais do solo, permanecendo alta nos sistemas de conservação avaliados e diferindo apenas do controle com preparo convencional. O IHO variou entre todos os sistemas e camadas avaliadas. O capim Xaraés, seguido por Piatã e Marandu, destacou-se na escarificação biológica do solo, similarmente à recuperação via preparo do solo, e B. decumbens apresentou desempenho intermediário, enquanto B. ruziziensis apresentou atividade semelhante ao pousio, indicando potencial limitado de recuperação física do solo.(AU)

Protein concentrates obtained from pig by-products using pH-shifting technique: a preliminary study / Concentrados proteicos obtidos de subprodutos suínos pela técnica de mudança do pH: um estudo preliminar

This study aimed to investigate the extraction and characterization of protein concentrates from pig by-products (heart, liver and kidneys) using the pH-shifting technique. From the solubility profiles (pH 2 to 12), the protein extraction was performed at alkaline pH (10.0 to 11.5), obtaining two fractions: soluble (SC) and insoluble (IC). Higher protein content (71 to 77%) and extractability (214 to 459 mg/g) were observed in heart and liver concentrates; whereas, for water holding capacity (WHC) the highest values (4.20 to 4.54 g water/g protein) were for the heart (SC) and kidney (SC and IC) concentrates. All concentrates had high emulsion stability and higher WHC than commercial protein extenders (whey and soybean). The concentrates obtained from the soluble fraction were redder (higher a* values and lower h values) and darker (lower L* values) than insoluble fraction, especially heart and liver concentrates. Use of concentrates in sausage production slightly altered the color chroma (C*) of samples. It was concluded that the pig by-products protein concentrates had great potential of use as extenders in sausage production.(AU)

Objetivou-se investigar a extração e caracterização de concentrados proteicos obtidos de miúdos suínos (coração, fígado e rins) pela técnica da solubilização isoelétrica. A partir das curvas de solubilidade (pH 2 a 12), a extração proteica foi realizada em pH alcalino (10,0 a 11,5), obtendo-se concentrados de duas frações: solúvel (CS) e insolúvel (CI). Maiores teores de proteína (71 a 77%) e solubilidade proteica (214 a 459 mg/g) foram observados nos concentrados do coração e do fígado, enquanto para a capacidade de reter água (CRA) os maiores valores (4,20 a 4,54 g água/g proteína) foram para os concentrados de coração (CS) e rins (CS e CI). Todos os concentrados apresentaram alta capacidade estabilizante e maior CRA do que extensores proteicos comerciais (soro de leite e soja). Os concentrados obtidos da fração solúvel eram mais vermelhos (maiores valores de a* e menores de h) e mais escuros (baixos valores de L*) do que os insolúveis, especialmente os concentrados de coração e fígado. O uso dos concentrados na elaboração de salsichas alterou ligeiramente a saturação (C*) da cor das amostras. Concluiu-se que os concentrados de subprodutos suínos apresentam grande potencial de uso como extensores na elaboração de salsichas.(AU)

High fire temperature changes soil aggregate stability in slash-and-burn agricultural systems

Fire is a key controlling factor in ecosystem dynamics worldwide, especially, in tropical areas under slash-and-burn agricultural systems. Farmers use fire as a tool to clean the land, and benefit from nutrient enrichment from ash-soil heating. However, fire can cause some detrimental effects on soil systems, such as organic carbon depletion, increased soil erodibility, and changes to aggregate stability. In this study, an experimental fire was applied to a plot of land following the local traditional practice of slash-and-burn. The fire temperature was monitored in the field, and its effect on soil aggregate stability was assessed. The fire temperature on soil surface was measured in four trenches, and it ranged from 355 to 660 ºC (average 484 ± 142 ºC). The fire temperature did not affect soil organic matter content. However, aggregate stability increased by 10 % in comparison to unburned soil. Moreover, the geometric mean diameter of burned soil was 20 % higher than that of unburned soil. In conclusion, high fire temperature changes soil aggregate stability in slash-and-burn agricultural systems.

High fire temperature changes soil aggregate stability in slash-and-burn agricultural systems

Fire is a key controlling factor in ecosystem dynamics worldwide, especially, in tropical areas under slash-and-burn agricultural systems. Farmers use fire as a tool to clean the land, and benefit from nutrient enrichment from ash-soil heating. However, fire can cause some detrimental effects on soil systems, such as organic carbon depletion, increased soil erodibility, and changes to aggregate stability. In this study, an experimental fire was applied to a plot of land following the local traditional practice of slash-and-burn. The fire temperature was monitored in the field, and its effect on soil aggregate stability was assessed. The fire temperature on soil surface was measured in four trenches, and it ranged from 355 to 660 ºC (average 484 ± 142 ºC). The fire temperature did not affect soil organic matter content. However, aggregate stability increased by 10 % in comparison to unburned soil. Moreover, the geometric mean diameter of burned soil was 20 % higher than that of unburned soil. In conclusion, high fire temperature changes soil aggregate stability in slash-and-burn agricultural systems.(AU)

Aggregates morphometry in a Latosol (Oxisol) under different soil management systems / Morfometria de agregados de um Latossolo sob diferentes sistemas de manejos do solo

Changes in soil physical properties are inherent in land use, mainly in superficial layers. Structural alterations can directly influence distribution, stability and especially morphometry of soil aggregates, which hence will affect pore system and the dynamic process of water and air in soil. Among the methods used to measure these changes, morphometry is a complementary tool to the classic methods. The aim of this study was to evaluate structural quality of a Latosol (Oxisol), under different management systems, using morphometric techniques. Treatments consisted of soil under no-tillage (NT); pasture (P), in which both had been cultivated for ten years, and an area under native vegetation (NV Savannah like vegetation). Aggregates were sampled at depths of 0-0.10 and 0.10-0.20 m, retained on sieves with 9.52 4.76 mm, 4.76 1.0mm, 1.0 0.5mm diameter ranges. Aggregate morphometry was assessed by 2D images from scanner via QUANTPORO software. The analyzed variables were: area, perimeter, aspect, roughness, Ferret diameter and compactness. Moreover, disturbed samples were collected at the same depths to determine particle size, aggregate stability in water, water-dispersible clay, clay flocculation index and organic matter content. It was observed that different soil management systems have modified soil aggregate morphology as well as physical attributes; and management effects magnitude increased from NT to P.(AU)

As alterações dos atributos físicos do solo, principalmente nas camadas superficiais, são inerentes ao uso do solo. Mudanças estruturais podem influenciar diretamente a distribuição, estabilidade e especialmente a morfometria dos agregados, o que afeta o sistema poroso e todo o processo dinâmico da água e ar no solo. Entre as metodologias que permitem mensurar estas alterações a morfometria apresenta-se como uma ferramenta complementar aos métodos tradicionais. Objetivou-se com esse trabalho avaliar a qualidade estrutural de um Latossolo Vermelho Distroférrico sob diferentes manejos do solo, empregando técnicas morfométricas. Os tratamentos deste estudo foram: o sistema plantio direto (PD), pastagem (P) ambos com dez anos de cultivo e área sob vegetação nativa (VN Cerrado). Foram amostrados agregados nas camadas de 0-0,10 e 0,10-0,20 m retidos no intervalo de 9,52 4,76 mm, 4,76 1,0mm, 1,0 0,5mm de diâmetro, obtidos por meio de um jogo de peneiras padrão. As análises dos agregados foram realizadas por meio de imagens 2D obtidas via scanner e analisadas com o programa QUANTPORO. As variáveis morfométricas avaliadas foram: Área, Perímetro, Aspecto, Rugosidade, Diâmetro de Ferret e Compacidade. Amostras com estrutura deformada foram coletadas nas mesmas profundidades para as seguintes determinações: granulometria, estabilidade de agregados em água, argila dispersa em água, grau de floculação e o conteúdo da matéria orgânica. Os diferentes sistemas de manejo do solo modificaram a morfometria dos agregados do solo, bem como seus atributos físicos, sendo que a magnitude dos efeitos causados pelo manejo aumenta no sentido do PD para a P.(AU)

FERMENTAÇÃO E ESTABILIDADE AERÓBIA DE SILAGENS DE MILHO INOCULADAS COM DIFERENTES CEPAS DE Lactobacillus buchneri

Objetivou-se avaliar inoculação de diferentes cepas selvagens de Lactobacillus buchneri sobre o perfil fermentativo e a estabilidade aeróbia (EA) de silagens de milho cultivadas em diferentes locais. Foi utilizado um esquema fatorial 4×5 (quatro inoculantes (I) e cinco locais de cultivo (L)), em um delineamento inteiramente casualizado, com quatro repetições. O milho foi semeado em áreas de cinco municípios. Os inoculantes avaliados foram: controle (CON; sem inoculante), LALSIL AS (Lallamend, Brasil), isolado LB 45.22 (L. buchneri) e isolado LB 90.14 (L. buchneri). As cepas LB 45.22 e LB 90.14 foram isoladas previamente de silagem de sorgo. Os inoculantes foram aplicados usando-se taxa de aplicação de 1x106 UFC g-1 de forragem, e os silos foram abertos após 60 dias de armazenamento. Houve efeito de local (P<0,001) para o teor de MS das silagens; as silagens do L1 apresentaram maior teor de MS em relação às dos demais locais. Houve efeito de local e inoculante para ácido lático (AL; P0,001) e ácido acético (AC; P0,003). Concentrações de AC foram maiores para silagens inoculadas com cepas selvagens. Houve efeito de interação L×I (P0,05) sobre as variáveis PB, FDN, PIDA, carboidratos solúveis em água (CHOs), nitrogênio amoniacal (N-NH3), pH e bactérias do ácido lático. Observou-se maior teor de FDN (P=0,032) para as silagens CON e LB 45.22 no L1, enquanto no L3, as silagens inoculadas apresentaram maior FDN (P=0,014). As silagens inoculadas com LB 45.22 e 90.14, nos L1, L2 e L3, apresentaram maior (P0,012) pH. A silagem inoculada com LB 90.14 no L3 apresentou maior (P=0,039) CHOs. Após sete dias de exposição aeróbia, houve efeito de interação L×I (P0,05) para as variáveis MS, CHOs, pH, EA, mofos e leveduras. A EA foi maior (P<0,001) para silagens inoculadas em relação às silagens CON, nos L1, L3 e L5; enquanto, nos L2 e L4, as silagens inoculadas com LB 90.14 apresentaram maior EA (P=0,026). As silagens inoculadas com os isolados, nos L2 e L3, apresentaram menor (P0,001) população de leveduras. Ainda, observou-se menor (P<0,001) contagem de leveduras para silagens inoculadas com LB 45.22 nos L1 e L5. A população de mofosfoi menor (P0,001) nas silagens inoculadas no L1 e L5, no entanto, foi menor (P=0,002) para as silagens inoculadas com os isolados no L3. Conclui-se que as cepas LB 45.22 e LB 90.14 melhoram a estabilidade aeróbia de silagens de milho e apresentam potencial como inoculantes na produção de silagens.

The objective of this study aimed to evaluate the inoculation of different wild strains of Lactobacillus buchneri on the fermentation profile and aerobic stability (AE) of corn silages grown in different locations. A 4×5 factorial scheme (four inoculants (I) and five cultivation sites (L)) was used, in a completely randomized design, with four replications. Corn was sown in areas of five municipalities. The inoculants obtained were: control (CON; no inoculant), LALSIL AS (Lallamend, Brazil), isolate LB 45.22 (L. buchneri) and isolate LB 90.14 (L. buchneri). Strains LB 45.22 and LB 90.14 were previously prepared from sorghum silage. The inoculants were applied at an application rate of 1x106 CFU g-1 of forage, and the silos were opened after 60 days of storage. There was a location effect (P<0.001) for the DM content of the silages; silages from L1 had higher DM content compared to other locations. There was site and inoculant effect for lactic acid (LA; P0.001) and acetic acid (CA; P0.003). CA concentrations were higher for silages inoculated with wild strains. There was an interaction effect of L×I (P0.05) on the variables CP, NDF, ADICP, water-soluble carbohydrates (WSC), ammonia nitrogen (NH3-N), pH and lactic acid bacteria. Greater NDF content (P=0.032) was observed for CON and LB 45.22 silages in L1, while not L3 as inoculated silages with higher NDF (P=0.014). The silages inoculated with LB 45.22 and 90.14, in L1, L2 and L3, dissipated higher (P0.012) pH. Silage inoculated with LB 90.14 at L3 had higher (P=0.039) WSC. After seven days of aerobic exposure, there was a L×I interaction effect (P0.05) for the variables DM, WSC, pH, AE, molds and yeasts. The AE was higher (P<0.001) for inoculated silages in relation to CON silages, in L1, L3 and L5; while, in L2 and L4, the silages inoculated with LB 90.14 aggregate greater AE (P=0.026). The silages inoculated with those obtained, in L2 and L3, smaller (P0.001) yeast population. Also, a lower (P<0.001) yeast count was observed for silages inoculated with LB 45.22 in L1 and L5. The mold population was smaller (P0.001) in the silages inoculated in L1 and L5, however, it was smaller (P=0.002) in the silages inoculated with those qualified in L3. It is concluded that strains LB 45.22 and LB 90.14 improve the aerobic stability of corn silages and have potential as inoculants in the production of silages.

Aggregate formation and soil organic matter under different vegetation in Atlantic Forest from Southeastern Brazil / Formação de agregados e matéria orgânica do solo sob diferentes tipos de vegetação na Floresta Atlântica do Sudeste do Brasil

Changes in soil use and management can affect the soil aggregation, including aggregate formation by biogenic and physicogenic processes. The aim of this study was to analyze physical and biological influences on the genesis of soil aggregates in areas with different vegetations in the Atlantic Forest, as well as to compare physical and chemical attributes of the aggregates formed in different ways. Undeformed soil samples were collected from a depth of 0-10 cm from second-growth forests at different successional stages and a pasture area. To identify the pathways of aggregation we used morphological patterns proposed by Bullock et al. (1985), and established three clusters: physicogenic, biogenic, and intermediates. The aggregates were analyzed for stability, exchangeable cations, distribution of total organic carbon (TOC), and oxidizable fractions of total organic carbon. In all areas evaluated, the percentage of physicogenic aggregates was higher than that of biogenic and intermediate aggregates. The biogenic aggregates with the highest mean weight diameter (MWD) and geometric mean diameter (GMD) were recorded for samples from the second-growth forest at an advanced stage of succession (SFAS) and from the mixed managed pasture (MMP) sites (MWD: 4.520 mm and 4.896 mm; GMD: 3.678 mm and 4.479 mm, respectively). The biogenic aggregates presented higher levels of K and P compared to the other morphological types in all areas studied, with higher P levels in the SFAS area. The TOC content was also higher in the biogenic aggregates in all study areas, with 22.33 g kg-1 in SFAS, 25.60 g kg-1 in the site with second-growth forest at the middle stage (SFMS) of succession, 24.74 g kg-1 in the site with second-growth forest at the initial stage (SFIS) of succession, and 20.28 g kg-1 in MMP. The highest content of the fractions F1 (6.93 g kg-1) and F2 (7.43 g kg-1) were found in the biogenic class compared to the intermediate and physicogenic aggregates.[...]

Mudanças no uso e manejo do solo podem afetar os processos de agregação, incluindo a formação de agregados por processos biogênicos e fisiogênicos. O objetivo deste estudo foi analisar a gênese de agregados por diferentes vias de formação, bem como atributos físicos e químicos dos agregados formados por essas vias em áreas com diferentes coberturas vegetais. Foram coletadas amostras de solo indeformadas na camada de 0-10 cm em áreas de floresta secundária com diferentes estádios sucessionais e uma área de pastagem. Para identificar as vias de agregação foram usados padrões morfológicos propostos por Bullock et al. (1985) e estabeleceu-se três grupos: fisiogênicos, biogênicas e intermediários. Os agregados foram analisados quanto à estabilidade em água, cátions trocáveis, teor de carbono orgânico total (COT) e frações oxidáveis do carbono orgânico total. Em todas as áreas avaliadas a porcentagem de agregados fisiogênicos foi maior do que a de agregados biogênicos e intermediários. Os agregados biogênicos foram encontrados em quantidade menor, com as maiores médias de Diâmetro Médio Ponderado (4.520 milímetros e 4.896 milímetros) e Diâmetro Médio Geométrico (3.678 milímetros e 4.479 milímetros) nas áreas de Floresta Secundária Estádio Avançado (FSEA) e Pasto Misto Manejado (PMM). Os agregados biogênicos apresentaram níveis mais elevados de K e P entre as classes morfológicas em todas as áreas estudadas, com os níveis de fósforo mais elevados na área de FSEA. O conteúdo COT também foi maior nos agregados biogênicos em todas as áreas de estudo, com 22.33 g kg-1 na FSEA, 25.60 g kg-1 na Floresta Secundária Estadio Médio (FSEM), 24.74 g kg-1 na Floresta Secundária Estadio Inicial (FSEI) e 20.28 g kg-1 em PMM. O maior teor de frações F1 (6.93 g kg-1) e F2 (7.43 g kg-1) foram encontrados na classe biogênica em comparação com agregados intermediários e fisiogênicos.[...]

Aggregate formation and soil organic matter under different vegetation in Atlantic Forest from Southeastern Brazil / Formação de agregados e matéria orgânica do solo sob diferentes tipos de vegetação na Floresta Atlântica do Sudeste do Brasil

Changes in soil use and management can affect the soil aggregation, including aggregate formation by biogenic and physicogenic processes. The aim of this study was to analyze physical and biological influences on the genesis of soil aggregates in areas with different vegetations in the Atlantic Forest, as well as to compare physical and chemical attributes of the aggregates formed in different ways. Undeformed soil samples were collected from a depth of 0-10 cm from second-growth forests at different successional stages and a pasture area. To identify the pathways of aggregation we used morphological patterns proposed by Bullock et al. (1985), and established three clusters: physicogenic, biogenic, and intermediates. The aggregates were analyzed for stability, exchangeable cations, distribution of total organic carbon (TOC), and oxidizable fractions of total organic carbon. In all areas evaluated, the percentage of physicogenic aggregates was higher than that of biogenic and intermediate aggregates. The biogenic aggregates with the highest mean weight diameter (MWD) and geometric mean diameter (GMD) were recorded for samples from the second-growth forest at an advanced stage of succession (SFAS) and from the mixed managed pasture (MMP) sites (MWD: 4.520 mm and 4.896 mm; GMD: 3.678 mm and 4.479 mm, respectively). The biogenic aggregates presented higher levels of K and P compared to the other morphological types in all areas studied, with higher P levels in the SFAS area. The TOC content was also higher in the biogenic aggregates in all study areas, with 22.33 g kg-1 in SFAS, 25.60 g kg-1 in the site with second-growth forest at the middle stage (SFMS) of succession, 24.74 g kg-1 in the site with second-growth forest at the initial stage (SFIS) of succession, and 20.28 g kg-1 in MMP. The highest content of the fractions F1 (6.93 g kg-1) and F2 (7.43 g kg-1) were found in the biogenic class compared to the intermediate and physicogenic aggregates.[...](AU)

Mudanças no uso e manejo do solo podem afetar os processos de agregação, incluindo a formação de agregados por processos biogênicos e fisiogênicos. O objetivo deste estudo foi analisar a gênese de agregados por diferentes vias de formação, bem como atributos físicos e químicos dos agregados formados por essas vias em áreas com diferentes coberturas vegetais. Foram coletadas amostras de solo indeformadas na camada de 0-10 cm em áreas de floresta secundária com diferentes estádios sucessionais e uma área de pastagem. Para identificar as vias de agregação foram usados padrões morfológicos propostos por Bullock et al. (1985) e estabeleceu-se três grupos: fisiogênicos, biogênicas e intermediários. Os agregados foram analisados quanto à estabilidade em água, cátions trocáveis, teor de carbono orgânico total (COT) e frações oxidáveis do carbono orgânico total. Em todas as áreas avaliadas a porcentagem de agregados fisiogênicos foi maior do que a de agregados biogênicos e intermediários. Os agregados biogênicos foram encontrados em quantidade menor, com as maiores médias de Diâmetro Médio Ponderado (4.520 milímetros e 4.896 milímetros) e Diâmetro Médio Geométrico (3.678 milímetros e 4.479 milímetros) nas áreas de Floresta Secundária Estádio Avançado (FSEA) e Pasto Misto Manejado (PMM). Os agregados biogênicos apresentaram níveis mais elevados de K e P entre as classes morfológicas em todas as áreas estudadas, com os níveis de fósforo mais elevados na área de FSEA. O conteúdo COT também foi maior nos agregados biogênicos em todas as áreas de estudo, com 22.33 g kg-1 na FSEA, 25.60 g kg-1 na Floresta Secundária Estadio Médio (FSEM), 24.74 g kg-1 na Floresta Secundária Estadio Inicial (FSEI) e 20.28 g kg-1 em PMM. O maior teor de frações F1 (6.93 g kg-1) e F2 (7.43 g kg-1) foram encontrados na classe biogênica em comparação com agregados intermediários e fisiogênicos.[...](AU)

Changes in physical properties and organic carbon of a Kandiudox fertilized with manure / Atributos físicos e carbono orgânico de um Nitossolo Vermelho com aplicação de dejetos

Successive applications of pig slurry and poultry manure can improve the soil structure, according to the land use conditions and amounts applied. This study evaluated the effect of manure fertilization on the physical properties and organic carbon of a Rhodic Kandiudox. Treatments included land use and management and time of pig slurry and poultry litter application, namely: native forest (NF); yerba mate after 20 years of animal waste application (YM20); pasture after 15 years of application (P15); grassland after 20 years of manuring (PP20); grassland after 3 years of manuring (P3); pasture without application (P0), maize after 20 years of application (M20); and maize after 7 years of application (M7). Soil samples were collected in the 0-5, 5-10 and 10-20cm layers, in which density, porosity, aggregate stability, flocculation, penetration resistance, available water, and total clay content, total and particulate organic carbon, and C:N ratio were analyzed. The total organic carbon is sensitive to management and was not related to waste application, except in the 10-20cm layer of ryegrass pasture after three years of manuring. Reponses to waste application and land use and management systems were observed in the variables soil density and penetration resistance.(AU)

Aplicações sucessivas de dejeto líquido de suínos e cama de aviário podem melhorar a estrutura do solo conforme as condições de uso do solo e quantidades adicionadas. Neste estudo, avaliou-se o efeito da aplicação desses fertilizantes sobre os atributos físicos e teores de carbono orgânico de um Nitossolo Vermelho. Os tratamentos contemplam sistemas de uso e manejo do solo e tempo de aplicação de dejeto líquido de suínos e cama de aviário, a saber: mata nativa (MN), erva mate com 20 anos de aplicação de dejetos animais (EM20), pastagem com 15 anos de aplicação (P15), pastagem com 20 anos de aplicação (PP20), pastagem com 3 anos de aplicação (P3), pastagem sem aplicação (P0), milho com 20 anos de aplicação (M20) e milho com 7 anos de aplicação (M7). As amostras de solo foram coletadas nas camadas 0-5, 5-10 e 10-20cm, nas quais foram analisadas: densidade, porosidade, estabilidade de agregados, grau de floculação, resistência à penetração, água disponível, argila total e os teores de carbono orgânico total e particulado e relação C:N. O carbono orgânico total é sensível ao manejo e não teve relação com a adição de dejetos, exceto na camada de 10-20cm na pastagem de azevém 3 anos. A densidade do solo e a resistência à penetração foram as variáveis que tiveram relação com a adição de dejetos e sistemas de uso e manejo do solo.(AU)

Aggregation agents and structural stability in soils with different texture and organic carbon contents

The flat pampas in the state of Santa Fe in Argentina have soils with high silt content, variable carbon content, and diverse degrees of structural degradation. Aggregate stability has been used as an indicator of the structural condition of the soil. This study aimed to quantify the effect of the addition of crop residues and root activity on the agents of aggregation and mechanisms of aggregate breakdown in soils with different carbon contents and textures cultivated under no-till. An experimental trial was conducted on a loamy soil (Typic Hapludoll, Santa Isabel series) and a silty soil (Typic Argiudoll, Esperanza series) under controlled conditions for 112 days with the following treatments: (i) with and without wheat plant growth and (ii) with and without addition of wheat residues. Soil structural stability by a method allowing for differentiation of aggregate breakdown by slaking, mechanical effect and microcracking, total organic carbon content, particulate organic carbon, glomalin and carbohydrate fractions was assessed. In general, the addition of residues and the presence of plant with active roots increased the presence of all aggregation agents and decreased aggregate breakdown processes in both soils. Soluble carbohydrates and proteins related to glomalin were the most important aggregating agents and their function was to reduce the magnitude of breakdown mechanisms, slaking and microcracking, evidencing a greater impact on the silty soil.

Aggregation agents and structural stability in soils with different texture and organic carbon contents

The flat pampas in the state of Santa Fe in Argentina have soils with high silt content, variable carbon content, and diverse degrees of structural degradation. Aggregate stability has been used as an indicator of the structural condition of the soil. This study aimed to quantify the effect of the addition of crop residues and root activity on the agents of aggregation and mechanisms of aggregate breakdown in soils with different carbon contents and textures cultivated under no-till. An experimental trial was conducted on a loamy soil (Typic Hapludoll, Santa Isabel series) and a silty soil (Typic Argiudoll, Esperanza series) under controlled conditions for 112 days with the following treatments: (i) with and without wheat plant growth and (ii) with and without addition of wheat residues. Soil structural stability by a method allowing for differentiation of aggregate breakdown by slaking, mechanical effect and microcracking, total organic carbon content, particulate organic carbon, glomalin and carbohydrate fractions was assessed. In general, the addition of residues and the presence of plant with active roots increased the presence of all aggregation agents and decreased aggregate breakdown processes in both soils. Soluble carbohydrates and proteins related to glomalin were the most important aggregating agents and their function was to reduce the magnitude of breakdown mechanisms, slaking and microcracking, evidencing a greater impact on the silty soil.(AU)

Dispersion index of aggregates in a Rhodic Ferrasol cultivated with cane under stillage application / Índice de dispersão de agregados de um Latossolo Vermelho distroférrico cultivado com cana sob aplicação de vinhaça

The sugar and alcohol plants generate waste stillage one that needs proper destination. One alternative is the application of this residue to improve soil properties. The objective of this study was to evaluate the effect of stillage in the aggregation and productivity of sugar cane grown in three seasons of the soil sampling. The study was conducted in an Red dystrophic Latosol, sandy clay frank, at the BUNGE Monte Verde plant in the municipality of Ponta Porã, MS, Brasil. Cultivated with sugarcane third year. We used the (4x4) factorial design, evaluated 4 applications of stillage (0, 450, 600 and 750 m3 ha-1) and their soil characteristics measured at four depths (0,0-0,5; 0,5-0,10; 0,10-0,20; 0,20-0,40 m) with five repetitions. To determine the rate of dispersion of aggregates (ID) sample were obtained undisturbed soil at 38, 75 and 111 days after application of stillage. With increasing doses of stillage were increased concentrations of potassium and organic matter and reduce the rate of dispersion and increased stability of soil aggregates.

As usinas de álcool e açúcar geram resíduos, sendo um deles a vinhaça a qual necessita de destino adequado. Uma das alternativas é a aplicação deste resíduo para melhoria de atributos do solo. Objetivouse com esse trabalho avaliar o efeito da vinhaça na agregação do solo, em três épocas de coleta e a produtividade da cana-de-açúcar cultivada. O estudo foi realizado em área cultivada com cana soca de terceiro ano em um Latossolo Vermelho distroférrico, de textura franco argilo arenoso no município de Ponta Porã, MS. O delineamento experimental foi de blocos casualizados, com cinco repetições, em parcelas sub-subdivididas, sendo quatro doses de vinhaça (0; 450; 600 e 750 m3 ha-1), quatro camadas (0,0-0,05; 0,05-0,10; 0,10-0,20 e 0,20-0,40 m), e três épocas de coleta, aos 38, 75 e 111 dias após aplicação das doses de vinhaça, em parcelas de 24 m2 (6m x 4m). Para a determinação do índice de dispersão dos agregados (ID) foram obtidas amostras de solo com estrutura preservada aos 38, 75 e 111 dias após aplicação das doses de vinhaça. Nas maiores doses de vinhaça o teor de potássio, de matéria orgânica e a estabilidade dos agregados aumentou e o índice de dispersão dos agregados diminuiu.

Dispersion index of aggregates in a Rhodic Ferrasol cultivated with cane under stillage application / Índice de dispersão de agregados de um Latossolo Vermelho distroférrico cultivado com cana sob aplicação de vinhaça

The sugar and alcohol plants generate waste stillage one that needs proper destination. One alternative is the application of this residue to improve soil properties. The objective of this study was to evaluate the effect of stillage in the aggregation and productivity of sugar cane grown in three seasons of the soil sampling. The study was conducted in an Red dystrophic Latosol, sandy clay frank, at the BUNGE Monte Verde plant in the municipality of Ponta Porã, MS, Brasil. Cultivated with sugarcane third year. We used the (4x4) factorial design, evaluated 4 applications of stillage (0, 450, 600 and 750 m3 ha-1) and their soil characteristics measured at four depths (0,0-0,5; 0,5-0,10; 0,10-0,20; 0,20-0,40 m) with five repetitions. To determine the rate of dispersion of aggregates (ID) sample were obtained undisturbed soil at 38, 75 and 111 days after application of stillage. With increasing doses of stillage were increased concentrations of potassium and organic matter and reduce the rate of dispersion and increased stability of soil aggregates.(AU)

As usinas de álcool e açúcar geram resíduos, sendo um deles a vinhaça a qual necessita de destino adequado. Uma das alternativas é a aplicação deste resíduo para melhoria de atributos do solo. Objetivouse com esse trabalho avaliar o efeito da vinhaça na agregação do solo, em três épocas de coleta e a produtividade da cana-de-açúcar cultivada. O estudo foi realizado em área cultivada com cana soca de terceiro ano em um Latossolo Vermelho distroférrico, de textura franco argilo arenoso no município de Ponta Porã, MS. O delineamento experimental foi de blocos casualizados, com cinco repetições, em parcelas sub-subdivididas, sendo quatro doses de vinhaça (0; 450; 600 e 750 m3 ha-1), quatro camadas (0,0-0,05; 0,05-0,10; 0,10-0,20 e 0,20-0,40 m), e três épocas de coleta, aos 38, 75 e 111 dias após aplicação das doses de vinhaça, em parcelas de 24 m2 (6m x 4m). Para a determinação do índice de dispersão dos agregados (ID) foram obtidas amostras de solo com estrutura preservada aos 38, 75 e 111 dias após aplicação das doses de vinhaça. Nas maiores doses de vinhaça o teor de potássio, de matéria orgânica e a estabilidade dos agregados aumentou e o índice de dispersão dos agregados diminuiu.(AU)

Argila e matéria orgânica e seus efeitos na agregação em diferentes usos do solo / Clay and organic matter and effects on aggregation in different soil uses

Mudanças no uso do solo afetam a quantidade de argila e matéria orgânica do solo (MOS) e estes, por sua vez, afetam a agregação. Avaliou-se como diferentes usos afetaram a agregação de um Argissolo na microrregião do Brejo Paraibano. Foram avaliadas três áreas contíguas com declive fortemente ondulado, sendo uma mata nativa, um plantio de sabiá (Mimosa caesalpiniaefolia) e uma pastagem com brachiaria (Brachiaria decumbens). Foram coletadas amostras de solo para determinação da textura, macro e microagregados secos (Macro-s e Micro-s) e úmidos (Macro-u e Micro-u), diâmetro médio ponderado de agregados secos (DMPA-s) e úmidos (DMPA-u), índice de estabilidade de agregados (IEA), teores de MOS e seu fracionamento em ácido fúlvico (AF), ácido húmico (AH) e humina (HUM), em quatro profundidades: 0,0-2,5 cm, 2,5-5,0 cm, 5,0-10,0 cm e 10,0-20,0 cm. Pôde-se notar que as quantidades de argila, MOS, HUM, Macro-s, Macro-u, DMPA-s, DMPA-u e IEA, são sempre maiores na área de mata nativa, em todas as profundidades. O plantio de sabiá apresentou maiores teores de AH e menores quantidades de Macro-u nas duas últimas profundidades em relação ao pasto. A HUM apresentou melhor correlação com a agregação do solo. Mudanças no uso causaram degradação do solo na microrregião do Brejo Paraibano.(AU)

Changes in soil use affect the amount of clay and soil organic matter (SOM) and these, in turn, affect the aggregation. It was evaluated how different uses affect the aggregation of the micro-region of Brejo Paraibano. Three adjacent areas were evaluated with strongly wavy slope, being one of them native forest, and the other ones a cultivation of sabiá (Mimosa caesalpiniaefolia) and a pasture of brachiaria (Brachiaria decumbens). Soil samples were collected for determination of texture, macro and dry microaggregates (Macro-s e Micro-s) and humid (Macro-u e Micro-u), mean weight diameter of dry aggregates (DMPA-s) and humid (DMPA-u), index of aggregate stability (IEA), contents of SOM and its fractionation in fulvic acid (FA), humic acid (HA) and humin (HUM) at four depths: 0.0-2.5 cm, 2.5-5.0 cm, 5.0-10.0 cm and 10.0-20.0 cm. It was observed that the amount of clay, SOM, HUM, Macro-s, Macro-u, DMPA-s, DMPA-u and IEA are always higher in native forest, at all depths. The cultivation of sabiá has presented higher contents of HA fraction and smaller amounts of Macro-u past two depths in relation to pasture. The HUM has shown better correlation with soil aggregation. Changes in the soil use have caused soil degradation in the microrregion of Brejo Paraibano.(AU)

Aggregate breakdown and dispersion of soil samples amended with sugarcane vinasse

Soil aggregation is a very complex issue related to important soil attributes and processes. The aggregate breakdown and dispersion of soil samples amended with sugarcane vinasse were evaluated using ultrasonic energy. Vinasse is an important byproduct of sugarcane industries, intensively applied to soils in Brazil as liquid fertilizer. Samples of two Oxisols and one Ultisol were used in this study. The physical and chemical characterization of soils was performed, and the 1 to 2 mm size aggregates (200 g) were packed in PVC columns (6.0 cm high and 4.0 cm internal diameter) and incubated with sugarcane vinasse under lab conditions for 1, 30 and 60 days. After incubation, aggregates were submitted to levels of ultrasonic energy, and the particle size distribution (53 to 2,000 µm, 2 to 53 µm, and 2 µm fractions) was quantified. Mathematical equations were used to relate the mass of aggregates in each of these fractions to the applied ultrasonic energy, and parameters related to aggregate stability were then obtained. Soils showed an aggregate-hierarchy resulting in a stepwise breakdown under ultrasonic agitation. Considering this soil-aggregation hierarchy, vinasse contributed even in a short time to the bonding between and within 2 to 53 µm aggregates, mainly in the Oxisols. This may be related to organic compounds present in the vinasse, cementing soil particles. Potassium enrichment of soil samples did not contribute to soil dispersion.

Aggregate breakdown and dispersion of soil samples amended with sugarcane vinasse

Soil aggregation is a very complex issue related to important soil attributes and processes. The aggregate breakdown and dispersion of soil samples amended with sugarcane vinasse were evaluated using ultrasonic energy. Vinasse is an important byproduct of sugarcane industries, intensively applied to soils in Brazil as liquid fertilizer. Samples of two Oxisols and one Ultisol were used in this study. The physical and chemical characterization of soils was performed, and the 1 to 2 mm size aggregates (200 g) were packed in PVC columns (6.0 cm high and 4.0 cm internal diameter) and incubated with sugarcane vinasse under lab conditions for 1, 30 and 60 days. After incubation, aggregates were submitted to levels of ultrasonic energy, and the particle size distribution (53 to 2,000 µm, 2 to 53 µm, and 2 µm fractions) was quantified. Mathematical equations were used to relate the mass of aggregates in each of these fractions to the applied ultrasonic energy, and parameters related to aggregate stability were then obtained. Soils showed an aggregate-hierarchy resulting in a stepwise breakdown under ultrasonic agitation. Considering this soil-aggregation hierarchy, vinasse contributed even in a short time to the bonding between and within 2 to 53 µm aggregates, mainly in the Oxisols. This may be related to organic compounds present in the vinasse, cementing soil particles. Potassium enrichment of soil samples did not contribute to soil dispersion.