RESUMO

Abstract in Brazil, management agricultural practices not currently consider the soil spatial variability as a result, crop growth can be non-uniform and yields often is low. This research aims to compare Kriging, Cokriging and Collocated cokriging using soil physical and hydraulic properties and their influences on soybean development. We hypothesized that spatial variability of physical and hydraulic properties has influence on soybean development and this variability can be better represented by Collocated Cokriging method. To test these hypotheses, we accessed the soil physical and hydraulic attributes in a field experiment under no-till system, cultivated with soybean. Geostatistical interpolators were applied to generate maps from which spatial dependence of the variables was evaluated. The experiment was conducted on a sandy clay loam Oxisol, on an experimental station located in Ponta Grossa, Paraná, Brazil. Evaluation of the soil attributes was performed: bulk density (BD), particle size distribution, saturated soil hydraulic conductivity (K fs ), total porosity (TP), macroporosity and microporosity. The plant was plant height and stand. Data analysis were performed by geostatistical methods; the spatial dependence was established using experimental univariate and cross semivariograms with datasets. Modeling semivariograms led to the generation of attribute maps by Kriging, Cokriging and Collocated cokriging. The estimation by Cokriging and Collocated cokriging was similar from Kriging. From the semivariogram, it was possible to identify that soil and plant attributes were spatially related with each other. The soya growth was mainly changed by slope of the area and little changed by saturated hydraulic conductivity.

RESUMO

In areas cultivated with oil palm, typically mechanized field operations using heavy vehicles may negatively affect soil physical properties and productivity. The aim of this study was to evaluate soil physical quality in an area cultivated with oil palm by monitoring the temporal variation of the soil water content and relating it to the critical limits of the least limiting water range. Soil bulk density (Bd), soil penetration resistance (SR), least limiting water range (LLWR), and water stress days (WSD) were used to assess soil physical quality in planting rows (PR) and the traffic zone (TZ) at depths 0-20, 20-40, and 40-60 cm. The Bd was higher and the LLWR was reduced in TZ only at the surface layer. The effect of temporal variation in soil water content on the soil physical quality was higher in TZ, mainly in subsurface layers. Bd and LLWR did not affect the fresh fruit bunch production; however, WSD in TZ at 20-40 and 40-60 cm layers provided evidence of effects of temporal variation of soil water content on oil palm productivity.

Assuntos

RESUMO

In areas cultivated with oil palm, typically mechanized field operations using heavy vehicles may negatively affect soil physical properties and productivity. The aim of this study was to evaluate soil physical quality in an area cultivated with oil palm by monitoring the temporal variation of the soil water content and relating it to the critical limits of the least limiting water range. Soil bulk density (Bd), soil penetration resistance (SR), least limiting water range (LLWR), and water stress days (WSD) were used to assess soil physical quality in planting rows (PR) and the traffic zone (TZ) at depths 0-20, 20-40, and 40-60 cm. The Bd was higher and the LLWR was reduced in TZ only at the surface layer. The effect of temporal variation in soil water content on the soil physical quality was higher in TZ, mainly in subsurface layers. Bd and LLWR did not affect the fresh fruit bunch production; however, WSD in TZ at 20-40 and 40-60 cm layers provided evidence of effects of temporal variation of soil water content on oil palm productivity.(AU)

Assuntos

RESUMO

Although anthropogenic dark earth (ADE) is generally found in non-floodable land, it also occurs on floodplains but, there is no information about the chemical and physical characteristics of ADE in this environment. In this study, we propose to check the hypothesis that a Gleysol, classified as ADE, presents improved chemical and physical conditions than an adjacent soil, no anthropogenic. Thus, the objective of this study was to characterize the chemical and physical properties of the top layer of two ADE profiles in a Gleysol and compare them with an adjacent soil. Samples were taken from two areas classified as ADE in Bragança, Pará State, Brazil, at the "Jabuti" archaeological site, and from an adjacent non-anthropogenic site. Disturbed and undisturbed soil samples were collected at the soil depth of 0.05-0.10 m for chemical (pH, potential acidity, exchangeable cations, and soil organic carbon) and physical (soil particle size distribution, particles density, water retention curve, total porosity, microporosity, macroporosity, and bulk density) analysis. The two areas of ADE in a Gleysol, showed improved soil chemical properties compared to the adjacent soil, particularly in relation to phosphorus and calcium levels that contributed to higher cation exchange capacity which, in turn, was positively related to organic carbon content. Changes in soil physical properties were less noticeable but both areas of ADE presented higher water retention capacity, particularly at low tension. The improved conditions of the ADE soil under Gleysols shows that these areas are adequate for soil cultivation, especially with plants adapted to floodplain.

Embora as terras pretas antropogênicas (TPA) geralmente são encontradas em áreas de terra firme, elas também ocorrem em áreas e várzeas, mas, não há informações sobre as características químicas e físicas de TPA neste ambiente. Neste estudo, nós propomos verificar a hipótese de que um Gleissolo, classificado como TPA, apresenta melhores condições químicas e físicas do que o solo adjacente, não antropogênico. Assim, o objetivo do estudo foi caracterizar as propriedades químicas e físicas da camada superficial de dois perfis de TPA em um Gleissolo e compará-los com um solo adjacente. Amostras de solo foram coletadas em duas áreas classificadas como TPA em Bragança, Estado do Pará, Brasil, no sítio arqueológico "Jabuti" e em uma área adjacente não antropogênica. Amostras de solo com estrutura deformada e indeformada foram coletadas na profundidade de 0,05-0,10 m para análises químicas (pH, acidez potencial, cátions trocáveis, e carbono orgânico do solo) e físicas (distribuição do tamanho das partículas do solo, densidade de partículas, curva de retenção de água, porosidade total, microporosidade, macroporosidade e densidade do solo). As duas áreas de TPA em Gleissolo, apresentaram melhores propriedades químicas comparadas com o solo adjacente, principalmente em relação aos níveis de fósforo e cálcio que contribuíram para a maior capacidade de troca catiônica que, por sua vez, foi positivamente relacionada com o conteúdo de carbono orgânico. Mudanças nas propriedades físicas do solo foram menos pronunciadas, mas as duas áreas de TPA exibiram maior capacidade de retenção de água, sobretudo em baixa tensão.

Assuntos

RESUMO

Although anthropogenic dark earth (ADE) is generally found in non-floodable land, it also occurs on floodplains but, there is no information about the chemical and physical characteristics of ADE in this environment. In this study, we propose to check the hypothesis that a Gleysol, classified as ADE, presents improved chemical and physical conditions than an adjacent soil, no anthropogenic. Thus, the objective of this study was to characterize the chemical and physical properties of the top layer of two ADE profiles in a Gleysol and compare them with an adjacent soil. Samples were taken from two areas classified as ADE in Bragança, Pará State, Brazil, at the "Jabuti" archaeological site, and from an adjacent non-anthropogenic site. Disturbed and undisturbed soil samples were collected at the soil depth of 0.05-0.10 m for chemical (pH, potential acidity, exchangeable cations, and soil organic carbon) and physical (soil particle size distribution, particles density, water retention curve, total porosity, microporosity, macroporosity, and bulk density) analysis. The two areas of ADE in a Gleysol, showed improved soil chemical properties compared to the adjacent soil, particularly in relation to phosphorus and calcium levels that contributed to higher cation exchange capacity which, in turn, was positively related to organic carbon content. Changes in soil physical properties were less noticeable but both areas of ADE presented higher water retention capacity, particularly at low tension. The improved conditions of the ADE soil under Gleysols shows that these areas are adequate for soil cultivation, especially with plants adapted to floodplain.(AU)

Embora as terras pretas antropogênicas (TPA) geralmente são encontradas em áreas de terra firme, elas também ocorrem em áreas e várzeas, mas, não há informações sobre as características químicas e físicas de TPA neste ambiente. Neste estudo, nós propomos verificar a hipótese de que um Gleissolo, classificado como TPA, apresenta melhores condições químicas e físicas do que o solo adjacente, não antropogênico. Assim, o objetivo do estudo foi caracterizar as propriedades químicas e físicas da camada superficial de dois perfis de TPA em um Gleissolo e compará-los com um solo adjacente. Amostras de solo foram coletadas em duas áreas classificadas como TPA em Bragança, Estado do Pará, Brasil, no sítio arqueológico "Jabuti" e em uma área adjacente não antropogênica. Amostras de solo com estrutura deformada e indeformada foram coletadas na profundidade de 0,05-0,10 m para análises químicas (pH, acidez potencial, cátions trocáveis, e carbono orgânico do solo) e físicas (distribuição do tamanho das partículas do solo, densidade de partículas, curva de retenção de água, porosidade total, microporosidade, macroporosidade e densidade do solo). As duas áreas de TPA em Gleissolo, apresentaram melhores propriedades químicas comparadas com o solo adjacente, principalmente em relação aos níveis de fósforo e cálcio que contribuíram para a maior capacidade de troca catiônica que, por sua vez, foi positivamente relacionada com o conteúdo de carbono orgânico. Mudanças nas propriedades físicas do solo foram menos pronunciadas, mas as duas áreas de TPA exibiram maior capacidade de retenção de água, sobretudo em baixa tensão.(AU)

Assuntos

RESUMO

Indicators synthesizing the state of the structural quality and the function of the porous system are useful for assessing soil production capacity as well as the way it may serve natural ecosystems. This research aimed (i) to determine indicators of the state and function of the porous system, (ii) to use them to derive a global index to characterize the soil physical quality, and iii) to establish a reference pore-size distribution curve for Mollisols from the province of Santa Fe (Argentina). Sixty water retention curves (WRC) of A and B horizons of Mollisols, with clay varying between 119 and 538 g kg1, organic matter between 5 and 40 g kg1, and soil bulk density between 1.09 and 1.49 Mg m3, were used. The indicators measured were: pore size distribution, macroporosity (PORp), air capacity (ACt) and plant-available water capacity (PAWC) among others. Soils were classified into four groups according to their physical properties and a reference WRC was determined. From this WRC and considering a total porosity of 0.514 m3 m3, PORp was 0.035 m3 m3, ACt 0.153 m3 m3, field capacity 0.361 m3 m3, permanent wilting point 0.136 m3 m3 and PAWC 0.225 m3 m3. Both the high silt content and low organic matter content confer on the soil characteristics with low stability, excess of small pores and low porosity of the macropore domain. Consequently, the capacity to quickly drain the water excess and allow root proliferation was not optimal, possibly due to the high silt or clay content and the low sand content, characteristic of the soil matrix of these Mollisols.

Assuntos

RESUMO

Indicators synthesizing the state of the structural quality and the function of the porous system are useful for assessing soil production capacity as well as the way it may serve natural ecosystems. This research aimed (i) to determine indicators of the state and function of the porous system, (ii) to use them to derive a global index to characterize the soil physical quality, and iii) to establish a reference pore-size distribution curve for Mollisols from the province of Santa Fe (Argentina). Sixty water retention curves (WRC) of A and B horizons of Mollisols, with clay varying between 119 and 538 g kg1, organic matter between 5 and 40 g kg1, and soil bulk density between 1.09 and 1.49 Mg m3, were used. The indicators measured were: pore size distribution, macroporosity (PORp), air capacity (ACt) and plant-available water capacity (PAWC) among others. Soils were classified into four groups according to their physical properties and a reference WRC was determined. From this WRC and considering a total porosity of 0.514 m3 m3, PORp was 0.035 m3 m3, ACt 0.153 m3 m3, field capacity 0.361 m3 m3, permanent wilting point 0.136 m3 m3 and PAWC 0.225 m3 m3. Both the high silt content and low organic matter content confer on the soil characteristics with low stability, excess of small pores and low porosity of the macropore domain. Consequently, the capacity to quickly drain the water excess and allow root proliferation was not optimal, possibly due to the high silt or clay content and the low sand content, characteristic of the soil matrix of these Mollisols.(AU)

Assuntos

RESUMO

No-tillage in Brazil is an efficient agricultural system that improves crop productivity whilst controlling erosion caused to the soil by degradation. However, there is some concern regarding soil compaction. Our objective was to determine whether the function of soil structure in sustaining crop growth was dependent on row and interrow positions in long-term no-tillage. We took soil samples from a field in a commercial farm under long-term no-tillage since 1979 on a clayey Oxisol in Southern Brazil. We assessed soil physical quality using the revised Peerlkamp technique and measured bulk density, air-filled porosity and air permeability of intact soil cores. Samples were incubated to assess in vitro N2O and CO2 production. The soil physical and structural properties showed consistent differences between interrow and row positions, where the properties measured were more favorable. The revised Peerlkamp technique proved as efficient as quantitative parameters in discriminating treatment differences. Overall, soil physical conditions in the interrow were less favourable than in the row. Pore continuity did not vary as regards position. This may explain why row position did not influence in vitro N2O and CO2 production. Soil physical quality under no-tillage system is enhanced, at least in the short term, by superficial disturbances in the row as a result of the action of the coulters of the no-tillage seeder.

Assuntos

RESUMO

No-tillage in Brazil is an efficient agricultural system that improves crop productivity whilst controlling erosion caused to the soil by degradation. However, there is some concern regarding soil compaction. Our objective was to determine whether the function of soil structure in sustaining crop growth was dependent on row and interrow positions in long-term no-tillage. We took soil samples from a field in a commercial farm under long-term no-tillage since 1979 on a clayey Oxisol in Southern Brazil. We assessed soil physical quality using the revised Peerlkamp technique and measured bulk density, air-filled porosity and air permeability of intact soil cores. Samples were incubated to assess in vitro N2O and CO2 production. The soil physical and structural properties showed consistent differences between interrow and row positions, where the properties measured were more favorable. The revised Peerlkamp technique proved as efficient as quantitative parameters in discriminating treatment differences. Overall, soil physical conditions in the interrow were less favourable than in the row. Pore continuity did not vary as regards position. This may explain why row position did not influence in vitro N2O and CO2 production. Soil physical quality under no-tillage system is enhanced, at least in the short term, by superficial disturbances in the row as a result of the action of the coulters of the no-tillage seeder.(AU)

Assuntos

RESUMO

O aumento da demanda pela avaliação da qualidade da estrutura do solo para o adequado crescimento de plantas tem motivado pesquisadores a desenvolverem técnicas visuais de avaliação, a campo, simples e confiáveis para esse fim. No Brasil, um número reduzido de estudos foi realizado empregando métodos visuais de diagnóstico do estado estrutural de solos no campo. Esse trabalho testou a hipótese de que o método de Avaliação Visual da Qualidade da Estrutura do Solo desenvolvido por BALL et al. (2007) para solos de clima temperado pode ser aplicado na identificação de campo da qualidade estrutural de um Latossolo Vermelho Distroférrico sob diferentes sistemas de uso e manejo. Para isso, foram avaliadas amostras indeformadas coletadas de mata preservada (M), sistema de integração lavoura-pecuária (ILP) e sistema plantio direto (SPD). A avaliação da estrutura apoiou-se na aparência, na resistência e nas características das unidades estruturais de blocos de solo e foi definida por cinco escores visuais de classificação de qualidade. O método empregado permitiu distinguir a qualidade do solo de diferentes sistemas de uso e manejo a partir da avaliação da estrutura da camada estudada.

The increasing demand for assessing soil structure for crop growth has motivated researchers to develop simple and reliable visual indicators to assess soil structure at the field. There are a few records in Brazil indicating the use of visual techniques for assessing soil physical quality. This paper tested the hypothesis that the Visual Soil Structure Quality Assessment methodology developed by BALL et al. (2007) is reliable for identifying the structural quality of tropical and subtropical soils under different soil management systems. Therefore, the overall objective of this paper was to visually identify the structural quality of an Oxisol under forest, crop-livestock rotation and no-till system. The structure evaluation was based on appearance, strength and characteristics of structural units from soil blocks, and was defined by five visual scores from the classification quality. The method allows distinguishing soil quality of the different soil use and management systems from the evaluation of the layer sampled.