Definition of management zones in coffee production fields based on apparent soil electrical conductivity

Domingos Sárvio Magalhães Valente,Francisco De Assis De Carvalho Pinto,Daniel Marçal De Queiroz,Fábio Lúcio Santos,Nerilson Terra Santos

doi:10.1590/s0103-90162012000300001

Domingos Sárvio Magalhães Valente, Francisco De Assis De Carvalho Pinto + Show 3 more

Open Access

https://doi.org/10.1590/s0103-90162012000300001

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Journal: Scientia Agricola	Publication Date: Jun 1, 2012
Citations: 29	License type: cc-by

Abstract

Fertilizer application at variable rates requires dense sampling to determine the resulting field spatial variability. Defining management zones is a technique that facilitates the variable-rate application of agricultural inputs. The apparent electrical conductivity of the soil is an important factor in explaining the variability of soil physical-chemical properties. Thus, the objective of this study was to define management zones for coffee (Coffea Arabica L.) production fields based on spatial variability of the apparent electrical conductivity of the soil. The resistivity method was used to measure the apparent soil electrical conductivity. Soil samples were collected to measure the chemical and physical soil properties. The maps of spatial variability were generated using ordinary kriging method. The fuzzy k-means algorithm was used to delimit the management zones. To analyze the agreement between the management zones and the soil properties, the kappa coefficients were calculated. The best results were obtained for the management zones defined using the apparent electrical conductivity of the soil and the digital elevation model. In this case, the kappa coefficient was 0.45 for potassium, which is an element that is associated with quality coffee. The other variable that had a high kappa coefficient was remaining phosphorous; the coefficient obtained was 0.49. The remaining phosphorus is an important parameter for determining which fertilizers and soil types to study.

Highlights

Coffee (Coffea Arabica L.) production is changing due to strong competition in the coffee market
Software was developed considering the follow steps: (i) model the semivariogram; (ii) perform the ordinary kriging to generate maps of spatial variability; (iii) delimit the management zones using a fuzzy k-means algorithm that is based on the maps of spatial variability; (iv) find the optimal number of classes, using the fuzziness performance index (FPI) and the modified partition entropy (MPE) and (v) calculate the kappa coefficient to analyze the how well the management zones represent the variables of a production field
For the ZMA, the FPI was minimized for two classes, and the MPE was minimized for five classes (Figure 2(a)

Summary

Introduction

Coffee (Coffea Arabica L.) production is changing due to strong competition in the coffee market. Producers are primarily concerned with coffee quality because higher quality allows them to charge higher prices. They are changing coffee production, since they are trying to find new cultivation methods that can improve yield and reduce production cost. One of the techniques used to reduce the number of required soil samples involves defining management zones based on information that can be collected at a low cost (Moral et al, 2010; Xin-Zhong et al, 2009; Zhang et al, 2010). The field information used to define management zones is based on maps of apparent soil electrical conductivity, digital elevation models, maps created using remote sensing and yield maps obtained from more than one crop (Fleming et al, 2004)

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