Abstract The terracing is important for erosion processes control in agricultural areas. However, agricultural terraces are being removed from the production areas under no-tillage systems. There are still uncertainties about the terracing effects on the soil saturated hydraulic conductivity (Ks) and macroporosity (Macro), which represent the functionality of the system. We aimed to evaluate the magnitude and spatial distribution of Ks and Macro and the correlation between these soil properties in two paired megaplots, of 1.923 ha, one with terraces (T) and another without terraces (WT). Ks and Macro were determined at 0.00-0.10 m, 0.10-0.20 m, 0.20-0.30 m, and 0.30-0.40 m soil layers and submitted to descriptive statistical, geostatistics, and Spearman correlation analysis. Ks was highest in the 0.00-0.20 m and lowest in the 0.20-0.40 m layers in T. In WT, Ks was highest in the 0.00-0.10 m and lowest in the 0.10-0.40 m layers. However, the Macro was highest in the 0.00-0.10 m and lowest in the 0.10-0.40 m layers in both megaplots. Ks and Macro had a positive correlation in both megaplots. The spatial distribution of Ks and Macro had a positive correlation, with regions with higher Ks coinciding with regions with higher Macro in both megaplots. The spatial distribution of Ks and Macro in WT did not have a clear trend, while in T there was a slight stratification in strips interspersed with higher and lower Ks and Macro. These initial trends are not conclusive considering the short term between terraces removal and Ks and Macro evaluation. However notillage no tillage systems (Ks Macro, , (Macro) system megaplots 1923 1 923 1.92 ha (T WT. . (WT) 0.000.10 000010 0.00 0.10 0 00 10 0.00-0.1 0.100.20 010020 0.20 20 0.10-0.2 0.200.30 020030 0.30 30 0.20-0.3 0.300.40 030040 0.40 40 0.30-0.4 statistical geostatistics analysis 0.000.20 000020 0.00-0.2 0.200.40 020040 0.20-0.4 0.100.40 010040 0.10-0.4 trend evaluation (Macro 192 92 1.9 (WT 000 0.000.1 00001 0.0 010 0.1 0.00-0. 100 0.100.2 01002 020 0.2 2 0.10-0. 200 0.200.3 02003 030 0.3 3 0.20-0. 300 0.300.4 03004 040 0.4 4 0.30-0. 0.000.2 00002 0.200.4 02004 0.100.4 01004 19 9 1. 0.000. 0000 0. 01 0.00-0 0.100. 0100 02 0.10-0 0.200. 0200 03 0.20-0 0.300. 0300 04 0.30-0 0.000 0.00- 0.100 0.10- 0.200 0.20- 0.300 0.30-

ABSTRACT Soil physical properties can be changed after vehicle traffic, especially by heavy military tracked vehicles. The Santa Maria military Instruction Field, where the experiment was carried out, is currently the most used area for armored tracked vehicles training in Brazil, with the M113 BR being the main equipment. The aim of this study was to determine the effect of the straight line and pivoted traffic intensity of the M113 BR on the physical properties and advancement of the compaction state of an Abruptic Alisol (Argissolo Vermelho-Amarelo Ta Distrófico abrúptico) with military vehicle traffic history. The study was conducted in a completely randomized design, independently evaluating the effect of straight and pivoting traffic in three soil layers (0.00-0.04, 0.10-0.14, and 0.20-0.24 m). For the straight-line traffic, traffic intensities (TI) with one (TI1), two (TI2), and five (TI5) passes on the same trail were evaluated. For the pivoting traffic, TI with one (TI1P) and two (TI2P) pivots was evaluated. Both studies had two non-traffic treatments (NT). The soil bulk density, total porosity, macroporosity, microporosity, saturated soil hydraulic conductivity, soil penetration resistance, soil bearing capacity, preconsolidation pressure, and gravimetric water content were analyzed in this study. In the straight-line traffic, cases with no significant differences in TP, Ma, Mi, and Ks prevailed. The highest TP, smallest Bd and largest Mi were observed in the 0.10-0.14 m layer. In the pivoting traffic, one pass was sufficient to increase Bd and decrease TP, Ma, Mi, and Ks in the 0.00-0.04 m layer and the increase from one to two pivotings had a significant difference only in Mi in this same layer. Both types of traffic intensity did not affect the PR in any layer. The Abruptic Alisol, pre-compacted from long-term military training, supported the loads applied by the M113 BR when additional traffic occurred in straight line mode, but not when in pivoting mode. The preconsolidation pressure parameter was not appropriate to assess the ability of the soil to support loads applied by pivoting traffic.

RESUMO A conversão de uma área de vegetação natural para uma área de cultivo associada às mudanças na cobertura vegetal podem acarretar modificações em algumas propriedades do solo, interferindo em sua qualidade. Dessa forma, o trabalho teve o objetivo de avaliar as alterações ocorridas nas propriedades físicas e químicas de um solo arenoso sob vegetação de campo nativo após a implantação de povoamentos de Eucalyptus dunnii Maiden, em diferentes densidades populacionais. O trabalho foi realizado na região da Campanha Gaúcha, município de São Francisco de Assis-RS. Foi instalado um experimento implantado com Eucalyptus dunnii Maiden sobre campo nativo, nos espaçamentos 3,50 m x 3,50 m; 3,50 m x 1,75 m; 1,75 m x 1,75 m e 1,75 m x 0,87 m, em um Argissolo Vermelho Distrófico. O delineamento experimental utilizado foi o de blocos ao acaso, com quatro repetições. Foram coletadas, em cada unidade experimental, amostras de solo nas profundidades de 0,00-0,10 m; 0,10-0,20 m e 0,20-0,40 m antes e após 12 meses da implantação. As propriedades físicas do solo avaliadas foram densidade, porosidade total, macroporosidade, microporosidade do solo e distribuição do tamanho dos agregados estáveis em água. As propriedades químicas determinadas foram: pH H2O, alumínio (Al), cálcio (Ca), magnésio (Mg), e potássio (K) trocáveis, fósforo disponível (P), nitrogênio total (N) e carbono orgânico total (C). Ocorreram alterações significativas na macro e microporosidade, na porcentagem dos agregados pertencentes à classe de tamanho de 8,00-4,75 mm e no DMG devido às práticas de preparo do solo e do manejo do povoamento no período inicial. Para as propriedades químicas do solo, houve aumento no pH e nos níveis de Ca no solo após 12 meses devido ao efeito da adubação aplicada.

ABSTRACT The conversion of natural vegetation to cultivated areas as well as changes in vegetation cover can lead to changes in some soil properties, interfering on their quality. Such changes occur in the soil structure and in the chemical properties. Therefore, the study has the objective to evaluate the changes in the physical and chemical properties of an Ultisol after afforestation of Eucalyptus dunnii Maiden planted in different spacing resulting in several plant populations. The study was accomplished in ‘Campanha Gaúcha’ region, in São Francisco de Assis city, Rio Grande do Sul state (RS). It was carried out an experiment planted with Eucalyptus dunnii Maiden planted on Ultisol with native grass. The plant spacings used were: 3,50 m x 3,50 m; 3,50 m x 1,75 m; 1,75 m 1,75 m and 1,75 m x 0,87 m. The experimental design was a complete randomized block with four replicates. It was collected soil samples were taken before the Eucalyptus planting and after twelve months, and layers of 0,00-0,10 m; 0,10-0,20 m and 0,20-0,40 m. The soil physical properties measured were: bulk density, total, macro and microporosity and wet aggregate size distribution. The soil chemical measured were: water pH, Al+++, Ca++, Mg++, K+, available P, N and C. There were change in the macro and microporosity, in the percentage of stable aggregates of size class 8,00-4,75 mm and DMG because to soil tillage and forest management. For the chemical properties there were increase in the pH and Ca content in the soil after twelve months by effect to fertilization applied.

RESUMO A região do Parque Estadual do Espinilho, inserida nos domínios fitogeográficos da Savana Estépica Parque, ainda é pouco estudada, apesar de ser destaque na flora sulina. Características como denso estrato herbáceo e árvores isoladas configuram-na como propícia à pecuária. Objetivou-se analisar alterações florísticas e edáficas impostas pelo pastejo em duas áreas do Parque, a primeira sob pastejo e a segunda protegida por cinco anos. Foram avaliadas propriedades físicas do solo e biomassa aérea do estrato herbáceo, visando investigar relações com as principais espécies arbóreas regenerantes. Foi instalada uma unidade amostral de 2ha em ambas as áreas, compostas por 200 subunidades cada. O inventário do estrato regenerante, as coletas para análises de solo, biomassa aérea do estrato herbáceo e testes de resistência do solo à penetração foram realizados em 50 subunidades. Os resultados avaliados pelo teste t de Student demonstram que há variações entre florística e fatores ambientais aferidos entre as duas áreas. A abundância das espécies P. affinis e V. caven e as variáveis resistência do solo à penetração, densidade do solo, umidade gravimétrica e biomassa aérea do estrato herbáceo diferem significativamente. A análise exploratória de ordenação (PCoA) permite inferir que variáveis densidade do solo, resistência à penetração e abundância de espécies de V. caven apresentam maiores valores em área com pastejo, e umidade gravimétrica, biomassa aérea e abundância de P. affinis são maiores em área protegida, configurando significativas mudanças ao longo de apenas cinco anos de exclusão.

ABSTRACT Despite being prominent in flora, the region of the Parque Estadual do Espinilho located in the Pampas of southern Brazil, where dense herbaceous stratum and isolated trees make this region suitable for livestock farming, has received little attention. The objective of the study was to analyze floristic and edaphic changes imposed by livestock farming in two areas of the park, the first under livestock grazing and the second protected from grazing (livestock-excluded) for five years. We evaluated soil physical properties of and the herbaceous aboveground biomass in order to investigate relationships with key regenerating tree species. A sampling unit of 2ha was installed in both areas, each composed of 200 subunits. Inventory of regenerating trees and herbaceous aboveground biomass, soil sampling, and soil penetration resistance tests were done in 50 subunits. The results, which were evaluated by Student’s t-test, exhibited variations between the two areas in regards to floristic and environmental factors. The abundance of the P. affinis and V. caven species and the variables of soil penetration resistance, soil bulk density, gravimetric moisture and herbaceous aboveground biomass differ significantly between the two areas. Principal coordinates analysis (PCoA) allows to infer that variables such as soil bulk density, penetration resistance and the abundance of V. caven species exhibit higher values in the area under gazing, while gravimetric moisture, aboveground biomass and abundance of P. affinis are higher in the area under livestock-excluded, showing that significant changes occur over just five years of livestock-excluded from the area.

A compactação do solo pelo tráfego de animais é uma preocupação em sistemas integrados lavoura-pecuária. Com o objetivo de avaliar o efeito de diferentes sistemas de manejo do solo e pisoteio de animais sobre os atributos físico-hídricos do solo e o desenvolvimento e a produtividade da soja, este experimento foi instalado no ano de 2007, em um Latossolo Vermelho distrófico cultivado anteriormente por uma década, pelo sistema de plantio direto de grãos em consórcio com forrageira. Avaliou-se a influência do pisoteio dos animais sobre a densidade (Ds), macroporosidade (Ma), microporosidade (Mi), porosidade total (PT), resistência do solo à penetração (RP) e o conteúdo de água no solo (θ), bem como a emergência, a altura e a produtividade da soja. O delineamento experimental foi blocos ao acaso com três repetições, com os tratamentos semeadura direta de soja sem pastejo (SD/SP), semeadura direta com pastejo em aveia (SD/CP) e escarificado com pastejo (ESC/CP). As amostras foram coletadas nas camadas de 0,00-0,07; 0,07-0,15; e 0,20-0,30 m, em três épocas: antes do pastejo (agosto de 2007), pós-pastejo (dezembro de 2007) e pós-pastejo (outubro de 2008). Não houve efeito significativo do pastejo sobre a Ds e PT. Aos 140 dias após a semeadura da soja, a RP atingiu valores acima de 2 MPa na camada de 0,00-0,15 m, nos tratamentos SD/SP e SD/CP, mas não limitando o desenvolvimento da cultura. A escarificação do solo sob integração lavoura-pecuária em semeadura direta proporcionou condições físico-hídricas menos favoráveis ao desenvolvimento das plantas; a altura de planta no SD/SP foi maior do que nos tratamentos SD/CP e ESC/CP e a menor produtividade de grãos foi obtida com a escarificação do solo, em ano com déficit hídrico.

Soil compaction from animal traffic is a concern in crop-livestock systems. This experiment was set up in 2007 with the aim of evaluating the effect of different soil management systems and animal traffic on soil physical and water properties and soybean development and yield. The soil evaluated was a dystrofic Red Latosol (Oxisol) under a no-tillage grain crop system intercropped with forage for the past decade. The effect of animal traffic was evaluated in regard to soil bulk density (Bd), macroporosity (Ma), microporosity (Mi), total porosity (TP), soil resistance to penetration (RP) and soil moisture content (θ), as well as soybean emergence, height and yield. A randomized block experimental design was used with three replications, with the treatments of no-tillage soybean cropping without grazing (SD/SP), no-tillage cropping with grazing in oats (SD/CP) and chisel plowing with grazing (ESC/CP). Soil samples were collected in the 0.00 to 0.07 m, 0.07 to 0.15 m and 0.20 to 0.30 m layers at three time periods: before grazing (August 2007), after grazing (December 2007) and after grazing (October 2008). There was no significant effect of grazing on Bd and TP. At 140 days after sowing of soybean, RP reached values above 2 MPa in the 0.00 to 0.15 m layer in the treatments SD/SP and SD/CP, without limiting crop development. Chisel plowing of the soil in crop-livestock integration under the no-tillage system led to soil physical-water conditions less favorable to plant development. Plant height in the SD/SP was greater than in the treatments SD/CP and ESC/CP, and the lowest grain yield was obtained through chisel plowing of the soil in a year with water deficit.

Os Neossolos são solos que apresentam inúmeras limitações de uso, principalmente relacionadas à sua profundidade efetiva, e têm sido muito pouco pesquisados no Brasil. Neossolos desenvolvidos sobre rochas sedimentares devem receber especial atenção para que sejam evitados danos ambientais, como a contaminação de aquíferos. O objetivo deste trabalho foi verificar o comportamento da condutividade hidráulica e a capacidade de retenção de água em perfis de Neossolos Litólicos e Neossolos Regolíticos derivados de arenito da Formação Caturrita no Rio Grande do Sul. Foram levantados dados morfológicos e determinadas a granulometria, porosidade, densidade do solo (Ds), condutividade hidráulica saturada (Ks), infiltração básica de água no campo (IB) e retenção de água em amostras de solo e saprolito de seis perfis de Neossolos. Os perfis apresentaram Ds elevada, baixa macroporosidade e alta microporosidade, o que contribuiu para baixa Ks e IB, mesmo em condições de textura franco-arenosa e camada saprolítica altamente fraturada. Os dados de Ks e IB apresentaram elevado coeficiente de variação entre os perfis analisados e entre as repetições de um mesmo perfil. A retenção de água teve valores superiores nas camadas Cr em relação aos horizontes A e volume superior de água disponível às plantas variável entre horizonte A e saprolito para os perfis analisados.

Leptosols and Regosols are soils with a series of restrictions for use, mainly related to the effective depth, which have been poorly studied in Brazil. These soils, when derived from sedimentary rocks should be treated with particular care to avoid environmental damage such as aquifer contamination. The purpose of this study was to verify the behavior of hydraulic conductivity and water retention capacity in profiles of Leptosols and Regosols derived from sandstone of the Caturrita formation in Rio Grande do Sul state. The morphology, particle size distribution, porosity, soil density (Ds), saturated hydraulic conductivity (Ks), basic water infiltration in the field (BI) and water retention were determined in soil and saprolite samples of six soil profiles. High Ds, low macroporosity and high microporosity were observed in the profiles, resulting in a low Ks and BI, even under conditions of sandy texture and a highly fractured saprolite layer. The variation coefficients of data of Ks and BI were high among the studied profiles and between replications of a same profile. Water retention of the studied soils was higher in Cr layers than in the A horizons and the volume of plant-available water greater and variable among A horizons and Cr layers.