REDUCTION OF SAMPLE SIZE IN THE ANALYSIS OF SPATIAL VARIABILITY OF NONSTATIONARY SOIL CHEMICAL ATTRIBUTES

Aim of study: To evaluate the influence of the parameters of the geostatistical model and the initial sample configuration used in the optimization process; and to propose and evaluate the resizing of a sample configuration, reducing its sample size, for simulated data and for the study of the spatial variability of soil chemical attributes under a non-stationary with drift process from a commercial soybean cultivation area. Area of study: Cascavel, Brazil Material and methods: For both, the simulated data and the soil chemical attributes, the Genetic Algorithm was used for sample resizing, maximizing the overall accuracy measure. Main results: The results obtained from the simulated data showed that the practical range did not influence in a relevant way the optimization process. Moreover, the local variations, such as variance or sampling errors (nugget effect), had a direct relationship with the reduction of the sample size, mainly for the smaller nugget effect. For the soil chemical attributes, the Genetic Algorithm was efficient in resizing the sampling configuration, since it generated sampling configurations with 30 to 35 points, corresponding to 29.41% to 34.31% of the initial configuration, respectively. In addition, comparing the optimized and initial configurations, similarities were obtained regarding spatial dependence structure and characterization of spatial variability of soil chemical attributes in the study area. Research highlights: The optimization process showed that it is possible to reduce the sample size, allowing for lesser financial investments with data collection and laboratory analysis of soil samples in future experiments.

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Spatial variability-based sample size allocation for stratified sampling

CATENA ◽

10.1016/j.catena.2021.105509 ◽

2021 ◽

Vol 206 ◽

pp. 105509

Author(s):

Shuangshuang Shao ◽

Huan Zhang ◽

Manman Fan ◽

Baowei Su ◽

Jingtao Wu ◽

...

Keyword(s):

Spatial Variability ◽

Sample Size ◽

Stratified Sampling ◽

Sample Size Allocation

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Magnetic susceptibility for characterizing areas with different potentials for sugarcane production

Pesquisa Agropecuária Brasileira ◽

10.1590/s0100-204x2016000900034 ◽

2016 ◽

Vol 51 (9) ◽

pp. 1349-1358 ◽

Cited By ~ 6

Author(s):

Diego Silva Siqueira ◽

José Marques Júnior ◽

Daniel De Bortoli Teixeira ◽

Sammy Sidney Rocha Matias ◽

Livia Arantes Camargo ◽

...

Keyword(s):

Magnetic Susceptibility ◽

Spatial Variability ◽

Exchange Capacity ◽

Strongly Correlated ◽

Soil Attributes ◽

Sugarcane Production ◽

Sugarcane Yield ◽

Chemical Attributes ◽

Physical And Chemical ◽

Variability Model

Abstract The objective of this work was to evaluate the use of magnetic susceptibility for characterizing the spatial variability of soil attributes and identifying areas with different potentials for sugarcane (Saccharum spp.) production. Samples were collected at 110 points (1 per 7 ha) in the layers of 0.00-0.20 and 0.20-0.40 m, to determine the magnetic susceptibility and physical and chemical attributes of the soil. Fiber content, sucrose polarization (POL), and sugarcane yield were determined in 33 points. The spatial variability model for magnetic susceptibility was 63 and 22% more accurate in delimiting soil potential for sugarcane production than soil physical and chemical attributes at the 0.0-0.2 and 0.2-0.4-m layers, respectively. The spatial variability map for magnetic susceptibility was strongly correlated with clay (0.83 and 0.89, respectively, for the layers) and sand contents (-0.84 and -0.88); moderately correlated with organic matter (-0.25 and -0.35), sum of bases (-0.46 and 0.37), cation exchange capacity (0.22 and 0.47), pH (-0.52 and 0.13), and POL (0.43 and 0.53); and weakly correlated with sugarcane yield (0.26 and 0.23). Magnetic susceptibility can be used to characterize the spatial variability of soil attributes and to identify areas with different potentials for sugarcane production.

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EFFECTS OF SPATIAL VARIABILITY OF SOIL CHEMICAL PARAMETERS ON TIFTON 85 GRASS YIELD1

Revista Caatinga ◽

10.1590/1983-21252020v33n125rc ◽

2020 ◽

Vol 33 (1) ◽

pp. 236-245

Author(s):

EUDOCIO RAFAEL OTAVIO DA SILVA ◽

MURILO MACHADO DE BARROS ◽

MARCOS GERVASIO PEREIRA ◽

JOÃO HENRIQUE GAIA GOMES ◽

STEPHANY DA COSTA SOARES

Keyword(s):

Decision Making ◽

Spatial Variability ◽

Dry Matter ◽

Irregular Sampling ◽

Descriptive Statistics ◽

Dry Matter Yield ◽

Chemical Parameters ◽

Tropical Pastures ◽

Chemical Attributes ◽

Soil Chemical Parameters

ABSTRACT Studies on spatial variability of soil attributes of tropical pastures gather information that can assist in decision making about managements of these soils. The objective of the present study was to evaluate the spatial variability of soil chemical attributes and their effects on grass yield of Tifton 85. The experiment was carried out in an area of 3.91 ha at the Feno Rio Farm of the Federal Rural University of Rio de Janeiro, Seropédica, RJ, Brazil. Soils of the 0-0.20 and 0.20-0.40 m layers were sampled considering an irregular sampling mesh, making a total of 50 georeferenced points. The parameters evaluated were: the soil chemical attributes pH, Al+3, Ca+2, Mg+2, Na+, K+, P, H+Al, and total organic carbon (TOC); and the Tifton 85 dry matter yield (DMY). The results of these parameters were subjected to descriptive statistics, linear correlation, and geostatistics, and maps were developed for the analyses. Regions with grass yields different from the general mean were found in the area, which presented mean grass yield of 2248 kg ha-1. The soil chemical parameters Na+, Ca+2, TOC, and H+Al were significantly correlated with DMY, confirming that they are important and affect the Tifton 85 grass yield. The mapping of the Tifton 85 cycle is important for understanding the variability of DMY. The investigation of areas with different productive potentials should be followed by development of maps of soil chemical attributes to correlate and understand the ratios that may be involved with these variations.

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Spatial variability analysis and mapping of soil physical and chemical attributes in a salt-affected soil

Arabian Journal of Geosciences ◽

10.1007/s12517-018-4207-x ◽

2019 ◽

Vol 12 (3) ◽

Cited By ~ 2

Author(s):

Masoomeh Delbari ◽

Peyman Afrasiab ◽

Bahram Gharabaghi ◽

Meysam Amiri ◽

Armand Salehian

Keyword(s):

Spatial Variability ◽

Variability Analysis ◽

Salt Affected Soil ◽

Chemical Attributes ◽

Physical And Chemical

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Spatial variability of soil fertility and its relation with cocoa yield

Revista Brasileira de Engenharia Agrícola e Ambiental ◽

10.1590/1807-1929/agriambi.v21n2p88-93 ◽

2017 ◽

Vol 21 (2) ◽

pp. 88-93 ◽

Cited By ~ 3

Author(s):

Railton O. dos Santos ◽

◽

Laís B. Franco ◽

Samuel A. Silva ◽

George A. Sodré ◽

...

Keyword(s):

Decision Making ◽

Fuzzy Logic ◽

Spatial Variability ◽

Soil Fertility ◽

Soil Properties ◽

Crop Yield ◽

Chemical Properties ◽

Western Region ◽

Chemical Attributes ◽

Cocoa Yield

ABSTRACT The knowledge on the spatial variability of soil properties and crops is important for decision-making on agricultural management. The objective of this study was to evaluate the spatial variability of soil fertility and its relation with cocoa yield. The study was conducted over 14 months in an area cultivated with cocoa. A sampling grid was created to study soil chemical properties and cocoa yield (stratified in season, off-season and annual). The data were analyzed using descriptive and exploratory statistics, and geostatistics. The chemical attributes were classified using fuzzy logic to generate a soil fertility map, which was correlated with maps of crop yield. The soil of the area, except for the western region, showed possibilities ranging from medium to high for cocoa cultivation. Soil fertility showed positive spatial correlation with cocoa yield, and its effect was predominant only for the off-season and annual cocoa.

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Spatial variability in soybean seeds quality and in chemical attributes of the soil of a production field in the Brazilian Cerrado

Journal of Seed Science ◽

10.1590/2317-1545v40n1182375 ◽

2018 ◽

Vol 40 (1) ◽

pp. 25-35 ◽

Cited By ~ 1

Author(s):

Danielle Helena Müller ◽

Elisangela Clarete Camili ◽

Walcylene Lacerda Matos Pereira Scaramuzza ◽

Maria Cristina de Figueiredo e Albuquerque

Keyword(s):

Spatial Variability ◽

Seed Production ◽

Seed Mass ◽

Soybean Seed ◽

Accelerated Aging ◽

Exchange Capacity ◽

Soybean Seeds ◽

Distribution Maps ◽

Chemical Attributes ◽

Definition Of

Abstract: The objective of this study was to evaluate the spatial variability in soybean seeds quality and in soil chemical attributes of a production field. Data were collected at 138 georeferenced points of a soybean production property located in Santo Antônio de Leverger - MT. Soil related variables, such as phosphorus, potassium, calcium, magnesium, and organic matter (OM) contents, pH, cation exchange capacity (CEC) and base saturation (V%) were evaluated. On the other hand, yield, one thousand seed mass, size, germination, emergence in seedbed, electrical conductivity, accelerated aging and tetrazolium reaction were evaluated as seed variables. The data were submitted to descriptive and geostatistical analysis, and the fit semivariogram parameters were used to elaborate spatial distribution maps of the analyzed variables. After the analysis, it was possible to conclude that there was spatial variability in the evaluated attributes for both seeds and soil related variables, indicating that the soybean seed production area can be divided into management zones, which allows the definition of areas to be harvested or discarded within a field of seed production.

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Spatial and multivariate analysis of soybean productivity and soil physical-chemical attributes

Revista Brasileira de Engenharia Agrícola e Ambiental ◽

10.1590/1807-1929/agriambi.v23n6p446-453 ◽

2019 ◽

Vol 23 (6) ◽

pp. 446-453

Author(s):

Ricardo N. Buss ◽

Raimunda A. Silva ◽

Glécio M. Siqueira ◽

Jairo O. R. Leiva ◽

Osmann C. C. Oliveira ◽

...

Keyword(s):

Spatial Variability ◽

Carbon Stock ◽

Management Strategies ◽

Covariance Structure ◽

Principal Component ◽

Spherical Model ◽

Soybean Yield ◽

Soil Attributes ◽

Physical Attributes ◽

Chemical Attributes

ABSTRACT The objective of this study was to evaluate the spatial variability of soybean yield, carbon stock, and soil physical attributes using multivariate and geostatistical techniques. The attributes were determined in Oxisols samples with clayey and cohesive textures collected from the municipality of Mata Roma, Maranhão state, Brazil. In the study area, 70 sampling points were demarcated, and soybean yield and soil attributes were evaluated at soil depths of 0-0.20 and 0.20-0.40 m. Data were analysed using multivariate analyses (principal component analysis, PCA) and geostatistical tools. The mean soybean yield was 3,370 kg ha-1. The semivariogram of productivity, organic carbon (OC), and carbon stock (Cst) at the 0-0.20 m layer were adjusted to the spherical model. The PCA explained 73.21% of the variance and covariance structure between productivity and soil attributes at the 0-0.20 m layer [(PCA 1 (26.89%), PCA 2 (24.10%), and PCA 3 (22.22%)] and 68.64% at the 0.20-0.40 m layer [PCA 1 (31.95%), PCA 2 (22.83%), and PCA 3 (13.85%)]. The spatial variability maps of the PCA eigenvalue scores showed that it is possible to determine management zones using PCA 1 in the two studied depths; however, with different management strategies for each of the layers in this study.

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SPACIAL VARIABILITY AND SAMPLING DENSITY OF CHEMICAL ATTRIBUTES IN ARCHAEOLOGICAL BLACK EARTH AND NATIVE FOREST SOIL IN MANICORÉ, AM

FLORESTA ◽

10.5380/rf.v44i4.29988 ◽

2014 ◽

Vol 44 (4) ◽

pp. 735 ◽

Cited By ~ 1

Author(s):

Ivanildo Amorim de Oliveira ◽

José Marques Júnior ◽

Milton César Costa Campos ◽

Renato Eleotério de Aquino ◽

Diego Silva Siqueira ◽

...

Keyword(s):

Spatial Variability ◽

Forest Soil ◽

Soil Samples ◽

Spatial Behavior ◽

Statistical Techniques ◽

Native Forest ◽

Sampling Density ◽

Lack Of Information ◽

Chemical Attributes ◽

Regular Spacing

AbstractConsidering the lack of information about spatial behavior of the soil attributes in areas of archaeological black earth and native forest, the objective of this study was to evaluate the spatial variability of chemical attributes and determine the sampling density in soil with archaeological black earth and native forest in the region of Manicoré, AM. The study was conducted in a rural property located in the community of Santo Antônio do Matupi, at the margins of BR 230, Trans-amazon highway, in the region of Manicoré, AM. In these areas were established grids of 70 m x 70 m, with regular spacing of 10 x 10 m, totaling 64 points, then soil samples were collected at a depth of 0.0-0.20 m and 0 , 40 - 0,60 m. Chemical attributes were determined (pH, OM, P, K, Ca, Mg, SB, CTC, V% and H + Al). Data were analyzed using descriptive statistical techniques and geostatistics. Sampling density was determined basing on CV and on the range of the semivariograms. It was verified that the studied attributes showed spatial variability and the area of archaeological black earth presented greater spatial variability than the native forest. Its greater sampling density was determined basing on the range of the adjusted semivariograms.Keywords: Indian black earth; attributes of soil; geostatistics.

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Small relief shape variations influence spatial variability of soil chemical attributes

Scientia Agricola ◽

10.1590/s0103-90162006000200008 ◽

2006 ◽

Vol 63 (2) ◽

pp. 161-168 ◽

Cited By ~ 20

Author(s):

Zigomar Menezes de Souza ◽

José Marques Júnior ◽

Gener Tadeu Pereira ◽

Diogo Mazza Barbieri

Keyword(s):

Spatial Variability ◽

Cation Exchange ◽

Sugar Cane ◽

Management System ◽

Cation Exchange Capacity ◽

Exchange Capacity ◽

Soil Samples ◽

Base Saturation ◽

Chemical Attributes

Soils with small variations in relief and under the same management system present differentiated spatial variabilities of their attributes. This variability is a function of soil position in the landscape, even if the relief has little expression. The aim of this work was to investigate the effects of relief shape and depth on spatial variability of soil chemical attributes in a Typic Hapludox cultivated with sugar cane at two landscape compartments. Soil samples were collected in the intercrossing points of a grid, in the traffic line, at 0-0.2 m and 0.6-0.8 m depths, comprising a set of 100 georeferenced points. The spatial variabilities of pH, P, K, Ca, Mg, cation exchange capacity and base saturation were quantified. Small relief shape variations lead to differentiated variability in soil chemical attributes as indicated by the dependence on pedoform found for chemical attributes at both 0-0.2 m and 0.6-0.8 m depths. Because of the higher variability, it is advisable to collect large number of samples in areas with concave and convex shapes. Combining relief shapes and geostatistics allows the determination of areas with different spatial variability for soil chemical attributes.

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