Navegando por Autor "Ajayi, Ayodele Ebenezer"

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Comparison of field and laboratory models of the load bearing capacity in coffee plantations
(Editora UFLA, 2013-03) Iori, Piero; Dias Junior, Moacir de Souza; Ajayi, Ayodele Ebenezer; Guimarães, Paulo Tácito Gontijo; Pais, Paula Sant'Anna Moreira; Andrade, Maria Luiza de Carvalho
Precompression stress is an important property for assessment of tropical soil structure sustainability and is often determined in laboratory tests. The objective of this study was to compare the load bearing capacity models obtained with controlled moisture in laboratory and those obtained with natural field moistures determined a long one year. The evaluation of soil structural sustainability follows four distinct steps: soil sampling in the field, uniaxial compression test of the samples in the laboratory, determination of precompression stress and estimation of the load bearing capacity models. Laboratory estimates of precompression stress were obtained from moisture controlled in laboratory and from natural moisture determined in a field a long one year. In this process, the soil samples were saturated by capillarity with distilled water in laboratory, and after 48 hours, the samples were air dried to obtain the different moisture contents. Then, the precompression stress was determined for this both conditions. To verify if the load bearing capacity models obtained with controlled moisture in laboratory may represent the load bearing models obtained with natural field moisture, these models were compared using the homogeneity test procedure. It was observed that 75% of field models analyzed were similar to the laboratory models. Thus, due to the similarity on the load-bearing capacity models obtained using natural (field) or controlled (laboratory) moisture contents, the assessment of the soil structure sustainability can be done using both methods.
Influence of field slope and coffee plantation age on the physical properties of a red-yellow latosol
(Sociedade Brasileira de Ciência do Solo, 2014-01) Iori, Piero; Dias Junior, Moacir de Souza; Ajayi, Ayodele Ebenezer; Guimarães, Paulo Tácito Gontijo; Abreu Júnior, Áureo Aparecido
In modern agriculture, several factors cause changes in the soil physical properties. The time of establishment of a crop (plantation age) and the slope are examples of factors that moderate the impact of mechanized operations on the soil structure. The objective of this study was to analyze the effect of machinery traffic on the physical properties of a Red-Yellow Latosol under coffee plantations with different ages (2, 7, 18, and 33 years) and slope positions (3, 9 and 15 %). Samples were collected from three positions between coffee rows (lower wheel track, inter- row and upper wheel track) and at two depths (surface layer and sub-surface). Changes in the total porosity, macroporosity, microporosity, organic matter, bulk density, and aggregate stability were investigated. Our results showed that the slope influenced the organic matter content, microporosity and aggregate stability. The soil samples under the inter-row were minimally damaged in their structure, compared to those from under the lower and upper wheel track, while the structure was better preserved under the lower than the upper track. The time since the establishment of the crop, i.e., the plantation age, was the main factor determining the extent of structural degradation in the coffee plantation.
Seasonal change of soil precompression stress in coffee plantation under sub-humid tropical condition
(Editora UFLA, 2014-04) Iori, Piero; Dias Junior, Moacir de Souza; Ajayi, Ayodele Ebenezer; Guimarães, Paulo Tácito Gontijo; Souza, Zélio Resende de; Figueiredo, Vanessa Castro
The objective of this study was to describe the seasonal change of precompression stress behavior in coffee plantations in the sub-humid tropic zone of Brazil as affected by agriculture traffic associated with the time since the establishment the coffee plantation, field slope, sampling position in and sampling depths. The coffee plantations on a uniform soil type; Red-Yellow Latosol were aged 2, 7, 18 and 33 years. Areas with side slope of 3, 9 and 15% were selected in these coffee plantations for this study. The soil was sampled at three positions on the coffee plantation row (bottom of traffic line, inter-row and top of traffic line) and at two depths (topsoil and sub-surface). Samples were collected over a one year period for each month of year. The study showed that the time since the establishment of a coffee farm and the slope steepness had significant effect on soil disturbance in mechanized operation. The coffee plantation with longer establishment time and on steeper terrain had higher precompression stress. The top traffic line presented higher load-bearing capacity than inter-row and bottom traffic line. The sites were more susceptible to compaction in the period from November to January of the year , because the Red-Yellow Latosol presented lower load-bearing capacity than the stress applied by tractor used in coffee management practices.
Spatial patterns of preconsolidation pressure and soil moisture along transects in two directions under coffee
(Sociedade Brasileira de Ciência do Solo, 2011-07) Gontijo, Ivoney; Dias Junior, Moacir de Souza; Guimarães, Paulo Tácito Gontijo; Oliveira, Marcelo Silva de; Ajayi, Ayodele Ebenezer
Information on the spatial structure of soil physical and structural properties is needed to evaluate the soil quality. The purpose of this study was to investigate the spatial behavior of preconsolidation pressure and soil moisture in six transects, three selected along and three across coffee rows, at three different sites under different tillage management systems. The study was carried out on a farm, in Patrocinio, state of Minas Gerais, in the Southeast of Brazil (18 o 59 ’ 15 ’’ S; 46 o 56 ’ 47 ’’ W; 934 m asl). The soil type is a typic dystrophic Red Latosol (Acrustox) and consists of 780 g kg -1 clay; 110 g kg -1 silt and 110 g kg -1 sand, with an average slope of 3 %. Undisturbed soil cores were sampled at a depth of 0.10–0.13 m, at three different points within the coffee plantation: (a) from under the wheel track, where equipment used in farm operations passes; (b) in - between tracks and (c) under the coffee canopy. Six linear transects were established in the experimental area: three transects along and three across the coffee rows. This way, 161 samples were collected in the transect across the coffee rows, from the three locations, while 117 samples were collected in the direction along the row. The shortest sampling distance in the transect across the row was 4 m, and 0.5 m for the transect along the row. No clear patterns of the preconsolidation pressure values were observed in the 200 m transect. The results of the semivariograms for both variables indicated a high nugget value and short range for the studied parameters of all transects. A cyclic pattern of the parameters was observed for the across-rows transect. An inverse relationship between preconsolidation pressure and soil moisture was clearly observed in the samples from under the track, in both directions.