Sampling grid density and lime recommendation in an Oxisol

Abstract

A B S T R A C TThe objective of this study was to evaluate the influence of different sampling grids density in the lime requirements in an Oxisol. The experiment was conducted at a rural property located in Sidrolândia city, Mato Grosso do Sul state, in the Brazilian 'Cerrado' . In the soil attributes mapping, regular sampling grid was used consisting of 99 points, spread over an area of 90 ha. Other two grids (51 and 27 points) were derived by deleting lines or lines and points from the original one. Based on the results of soil analysis, the lime requirement at each sample point was calculated. Using geostatistical techniques the spatial variability of lime requirement was studied and grid configuration for each sample was tested. By kriging, maps were made. By reducing the number of sampling points, 11% of the experimental area showed an overestimation and 8% underestimation comparing with the lime requirement made using the highest sampling grid density.

Transition From Systematic to Directed Soil Sampling Designs in an Area Managed With Precision Agriculture

“…The data indicated that an increase in the dimension of the sampling grid promoted a reduction in the coefficients of determination (R 2 ) of theoretical models, as reported by Bottega et al (2014). The spatial dependence was classified as weak for grids with cell sizes of 0.5 and 1 ha for soil pHwater and soil K content, respectively.…”

“…The total cost of inputs recommended (lime and TSP) for the area showed little variation among the sampling designs, as observed by Bottega et al (2014). However, the amount of inputs recommended from systematic samplings were slightly higher when compared to directed samplings.…”

“…Data from directed sampling designs suggested that P fertilization was no necessary in that field. It reveals that this alternative methodologies were inefficient in showing subareas of the field that had fertilizer application requirement, which can induce reductions of crop yield in these subareas (Bottega et al, 2014, Cherubin et al, 2015, CQFS-RS/SC, 2016. The cost of the triple superphosphate (TSP) incorrectly recommended (higher and lower doses than the reference) using systematic sampling with grid of 1 ha was R$ 1,238.00 (approximately R$ 10.00 per ha).…”

“…However, some Engenharia Agrícola, Jaboticabal, v.39, n.3, p.400-409, may/jun. 2019 methodological procedures remains unclear (Siqueira et al, 2014), such as the size of cells and consequently the number of soil samples per hectare (Nanni et al, 2011, Bottega et al, 2014, Cherubin et al, 2014. The difficulty in defining the dimension of the grid cells is associated with the different patterns in the spatial variability of each of the soil chemical properties within the field and between fields (Mallarino & Wittry, 2004, Nanni et al, 2011, Cherubin et al, 2014.…”

Vegetation indexes and delineation of management zones for soybean1

“…Foram identificadas diferenças nos teores de fósforo, argila e silte, nas zonas de manejo delineadas. (Song et al 2009), and the identification of these zones within a crop can be made from different techniques and sources of information, such as yield maps (Xiang et al 2007) and soil sampling grids (Bottega et al 2014). The use of sensors that measure mechanical, physical and chemical properties has also been highlighted for this purpose, especially when associated with soil attributes (Adamchuk et al 2004).…”