Tamanho da subamostra e representatividade da fertilidade do solo no sistema plantio direto

Schlindwein, Jairo André; Anghinoni, Ibanor

doi:10.1590/s0103-84782002000600008

Cited by 14 publications

(15 citation statements)

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“…Para Schilindwein e Anghinoni (2002), o número de amostras deve contemplar as macrovariações (> 2 m), enquanto a forma, o volume (área da amostra) e o local de amostragem devem contemplar as meso (5 cm a 2 m) e as microvariações (< 5cm). Esses autores compararam teores de P e K disponíveis, determinados ao se coletar amostras simples de diferentes volumes (áreas diferentes para uma mesma profundidade) e observaram que os coef icientes de variação (CV) dos teores de P e K diminuíram com o aumento da área das amostras simples, independentemente da forma da seção (retangular ou quadrada).…”

Section: Forma Da Amostra Simples De Solounclassified

Fundamentação teórica dos sistemas de amostragem de solo de acordo com a variabilidade de características químicas.

Guarçoni

Álvarez

Sobreira

2017

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Devido à elevada variabilidade de determinadas características químicas, a amostragem de solo é uma das mais importantes fontes de erro em um programa de correção e adubação. O objetivo dessa revisão foi analisar criticamente os fundamentos teóricos que def inem os tipos de amostragem de solo utilizados para diferentes sistemas de cultivo, avaliando o grau de influência das variações de características químicas conferidas por cada situação. Confrontando informações dos trabalhos consultados, foi possível inferir que a estratif icação do terreno em unidades de amostragem diminui a ocorrência de dependência espacial causada por fatores do ambiente associados às variações de longa distância (macrodependência), mas não impede a ocorrência de dependência espacial a curtas distâncias em locais dentro do próprio estrato (mesodependência). A opção de se utilizar a análise da amostra composta por unidade de amostragem (fertilidade média) ou os mapas de fertilidade do solo, para recomendação de corretivos e fertilizantes, deve-se especialmente a questões econômicas. A coleta de amostras simples de pequeno volume e obtenção de médias locais, ou a formação de amostras compostas a partir destas “amostras simples”, tende a incrementar a efetividade e a conf iabilidade dos mapas de fertilidade.

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Section: Forma Da Amostra Simples De Solounclassified

Fundamentação teórica dos sistemas de amostragem de solo de acordo com a variabilidade de características químicas.

Guarçoni

Álvarez

Sobreira

2017

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“…Less mobile elements, such as P, in soils have greater horizontal and vertical variability in NT than CT due to the residual effect of fertilizers on the soil surface and in the plant row (Schlindwein and Anghinoni, 2002). An increase in surface P contents in soils in low-tillage systems (NT and RT) has been reported by other authors (Santos et al, 2008;Costa et al, 2009).…”

Section: Resultsmentioning

confidence: 99%

“…For example, Santos et al (2008) and Costa et al (2009) found results that support that no-tillage and reduced tillage systems are able to increase P and Ca 2+ contents. However, the vertical distribution of these chemical elements in the soil profile can be affected by the use of low disturbance systems (Schlindwein and Anghinoni, 2002). This is especially important for elements that have low mobility in soils, which are generally maintained on the surface, and it can be associated with processes and properties such as specific adsorption and the preference of cations with high ionic strength for adsorption sites.…”

Section: Introductionmentioning

confidence: 99%

Management Systems Effect on Fertility Indicators of a Ferralsol with Vegetable Crops, as Determined by Different Statistical Tools

Lima

Silva

Guedes

et al. 2017

Rev. Bras. Ciênc. Solo

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ABSTRACT:The intensive nature of soil use in vegetable production areas has led to a marked decrease in soil quality. The objective of this study was to evaluate the effects of adoption of soil management systems on vegetable production with regards to the chemical properties of a Rhodic Ferralsol after five years and to evaluate the use of the Principal Component Analysis (PCA) statistical tool in discriminating the different treatments. The experiment was conducted under field conditions in central Brazil in a randomized block design with four replications and a 3 × 2 factorial arrangement (three soil management systems × two cover crops). The soil management systems used were NT (no-tillage), RT (reduced tillage), and CT (conventional tillage). The cover crops used were corn (Zea mays) alone and corn intercropped with the gray velvet bean (Stizolobium niveum). Reduced tillage showed the highest values of sum of bases, cation exchange capacity (T), and total organic carbon contents in the 0.00-0.05 m layer. In the same layer, RT and CT showed higher values of pH and K content. No-tillage and RT showed the highest P and Ca 2+ contents and H+Al and T values. In the 0.05-0.10 m layer, RT had higher a pH value and Mg 2+ contents. No-tillage and CT had higher potential acidity in this layer. The management systems (0.10-0.30 m) and the cover plants (all layers) had no effect on the properties analyzed. The use of PCA determined that the two principal components explained the following percentage of the data variance: 90.8 % (0.0-0.05 m), 79.8 % (0.05-0.10 m), and 83.1 % (0.10-0.30 m). Analysis of the eigenvectors and the grouping of treatments in PCA also showed that RT was most effective in improving soil fertility properties. Reduced tillage was most effective in increasing soil fertility after five years. The PCA is recommended as a useful tool and it allowed the identification of patterns not revealed by traditional tools.

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“…Therefore, land leveling did not significantly change the variance values for the great majority of the data sets. According to Schlindwein & Anghinoni (2002), in the case of precision agriculture, an increase in the variance of a set of measurements implies an increase in the number of samples that need to be collected for a given probability level. Among the properties evaluated before leveling (Table 1), only the EC data did not follow normal distribution according to the Kolmogorov-Smirnov test (p<0.05), while after leveling, clay, silt, sand, Disp clay, Pd and WAD also did not follow normality, indicating that these properties showed a localized distribution in the experimental area (Grego et al, 2006), and the mean value cannot be considered the center of the distribution (Nielsen & Wendroth, 2003 Disp clay: dispersed clay, Bd: bulk density, Pd: particle density, Tp: total porosity, Macro: macroporosity, Micro: microporosity, WAD: weighted average diameter, AWC: available water capacity, EC: electrical conductivity.…”

Section: Resultsmentioning

confidence: 99%

Impacts of land leveling on lowland soil physical properties

Parfitt

Timm²,

Reichardt

et al. 2014

Rev. Bras. Ciênc. Solo

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SUMMARYThe practice of land leveling alters the soil surface to create a uniform slope to improve land conditions for the application of all agricultural practices. The aims of this study were to evaluate the impacts of land leveling through the magnitudes, variances and spatial distributions of selected soil physical properties of a lowland area in the State of Rio Grande do Sul, Brazil; the relationships between the magnitude of cuts and/or fills and soil physical properties after the leveling process; and evaluation of the effect of leveling on the spatial distribution of the top of the B horizon in relation to the soil surface. In the 0-0.20 m layer, a 100-point georeferenced grid covering two taxonomic soil classes was used in assessment of the following soil properties: soil particle density (Pd) and bulk density (Bd); total porosity (Tp), macroporosity (Macro) and microporosity (Micro); available water capacity (AWC); sand, silt, clay, and dispersed clay in water (Disp clay) contents; electrical conductivity (EC); and weighted average diameter of aggregates (WAD). Soil depth to the top of the B horizon was also measured before leveling. The overall effect of leveling on selected soil physical properties was evaluated by paired "t" tests. The effect on the variability of each property was evaluated through the homogeneity of variance test. The thematic maps constructed by kriging or by the inverse of the square of the distances were visually analyzed to evaluate the effect of leveling on the spatial distribution of the properties and of the top of the B horizon in relation to the soil surface. Linear regression models were fitted with the aim of evaluating the relationship between soil properties and the magnitude of cuts and fills. Leveling altered the mean value of several soil properties and the agronomic effect was negative. The mean values of Bd and Disp clay increased and Tp, Macro and Micro, WAD, AWC and EC decreased. Spatial distributions of all soil physical properties changed as a result of leveling and its effect on all soil physical properties occurred in the whole area and not specifically in the cutting or filling areas. In future designs of leveling, we recommend overlaying a cut/fill map on the map of soil depth to the top of the B horizon in order to minimize areas with shallow surface soil after leveling.Index terms: soil management practices, land forming, irrigated rice crop, soil movement, soil properties. RESUMO: IMPACTO DA SISTEMATIZAÇÃO NOS ATRIBUTOS FÍSICOS DE UM SOLO DE VÁRZEAA sistematização altera a superfície natural do solo criando uma área com declividade uniforme com a finalidade de facilitar todas as operações agrícolas. Os objetivos deste trabalho foram de determinar os impactos da sistematização sobre: a magnitude, a variância e a distribuição espacial de alguns atributos físicos de uma área em solos de várzea no Estado do Rio Grande do Sul; a relação entre a magnitude dos cortes e, ou, os aterros e os atributos físicos do solo, após a sistematização da área; e a distrib...

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Tamanho da subamostra e representatividade da fertilidade do solo no sistema plantio direto

Abstract: RESUMO Os corretivos e fertilizantes, quando aplicados de forma localizada, mantêm-se ao longo das linhas de cultivo no sistema plantio direto. Isto se reflete no aumento da variabilidade horizontal dos atributos químicos do solo, causando dificuldades para a coleta de

Cited by 14 publications

References 1 publication

Fundamentação teórica dos sistemas de amostragem de solo de acordo com a variabilidade de características químicas.

Fundamentação teórica dos sistemas de amostragem de solo de acordo com a variabilidade de características químicas.

Management Systems Effect on Fertility Indicators of a Ferralsol with Vegetable Crops, as Determined by Different Statistical Tools

Impacts of land leveling on lowland soil physical properties

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