This document discusses using electrical resistivity to determine soil properties influencing yam yield. It describes how electrical resistivity can be used to identify areas of poor crop growth. The study aims to assess the relationship between electrical resistivity and soil properties under yam cultivation, and determine the correlation between yam yield and electrical resistivity. The document outlines the materials and methods, including the experimental design, soil sampling, and data analysis that will be used to study two varieties of water yam over two growing seasons.

1. USE OF ELECTRICAL RESISTIVITY TO
DETERMINE SOIL PROPERTIES
INFLUENCING THE YIELD OF YAM
BY
Solomon Takwa HABU
B. AGRIC. (ABU)
MATRIC. NUMBER: 189138
SUPERVISOR: DR. S. O. OSHUNSANYA
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The changes in soil due to intensive agricultural
production differ with time.
Those methods based on the electric properties are
promising techniques (Bullock and Bullock, 2000).
The potential of using soil resistivity for
predicting crop yield has been reported for cotton
(Jaynes et al., 1995), (Dabas et al.,1989) used soil
map to identified areas of poor crop growth in a
field by precise electrical soil mapping.
INTRODUCTION

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Definition of soil electrical resistivity (Ωm).
Methods of determining insitu Electrical
resistivity in the field of Agriculture include;
 Contact electrode (CE)
 Electromagnetic induction (EM)
Principles of the contact electrode.
Constraints. Moisture content, salinity and
temperature.
INTRODUCTION CONT’D

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INTRODUCTION CONT’D
Electrical resistivity variability is closely linked
with the crop yield at the field scale for Irish potato
(Zanolin, 2003).
The patterns of soil electrical resistivity within a
field do not tend to change significantly over time
(Lund et al., 1999).
Potential difference provides information on the
form of heterogeneities in soils and their electrical
properties (Kearey et al., 2002).

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INTRODUCTION CONT’D
Why the choice of yam for this experiment?
Adaptation.
Progressive decline in yam yield in some
traditional producing areas (Oikeh et al., 1999).
Management of soil fertility to achieve
sustainable productivity in yam production
cannot be over emphasiszed.

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There is need for efficient management and
utilization of the heterogeneity of tropical soils to
maximize production capacities (Vanlauwe et al.,
2006).
There is little or no information as regard the
subject for yam.
 Electrical resistivity offers the most veritable
techniques to determine soil properties influencing
yield under various agronomic conditions (Kearey
et al., 2002).
JUSTIFICATION

7. OBJECTIVES
To assess the relationship between
electrical resistivity and soil properties
under yam cultivation.
To determine the correlation between yam
yield and electrical resistivity.
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8. MATERIALS AND METHODS
Study area: The Teaching and Research Farm of
the University of Ibadan (latitude 7° 24' 02.9"N,
longitude 3° 54' 26.25"E) Nigeria. The field was
used for the experiment in 2014/2015 season
planted to two different cultivars of water yam
(Dioscorea alata L.).
The same two cultivars were planted for the
season 2015/2016 at 1m x1m spacing.
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9. Experimental design: The experimental design
is RCBD with two cultivars of water yam
(Dioscorea alata L.) used as treatment
replicated twelve times. Each replicate contain
6m x 3m plot.
The two Dioscorea alata L. cultivars obtained
from IITA are:
TDa 00/00194
TDa 00/00006
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MATERIALS AND METHODS CONT’D

10. Soil samples were collected at 0-15cm, 15-30cm
and 30-45cm depths. Two undisturbed soil cores
(5×5cm in diameter) were collected per plot to
determine bulk density, total porosity, volumetric
moisture content and hydraulic conductivity.
Composite samples from each replicate will be
used to determine soil pH, N, SOM, P, k, Na, Mg,
CEC, Al, Fe, Cu and particle size distribution.
The soil electrical resistivity will be determined
using the Miller resistivity meter (V3100).
MATERIALS AND METHODS CONT’D
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11. Figure 1: The contact electrode resistivity meter (Vries 3100)
MATERIALS AND METHODS CONT’D
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12. Figure 2: Typical range of electrical resistivity of some earth materials
(Palacky, 1987) 12
S/N Property Resistivity range
(Ωm)
Earth material
1 Texture >160 Ωm <300 Sand
>80 Ωm <160 Silt
>5 Ωm <80 Clay
2 Pore size
distribution
>80 Ωm <250 Micro-pore
>250 Ωm <500 Macro-pore
3 Salinity <0.4 Ωm Low Salinity
>0.4 Ωm <1 High Salinity
4 Bulk density <1000 Low BD
>1000 High BD
Electrical Resistivity Range

13. DATAANALYSIS
Data collected will be subjected to analysis of
variance (ANOVA) using SPSS 20.0 package.
The means will be separated using the Duncan`s
Multiple Range Test (DMRT).
Correlation and regression analysis will also be
employed.
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14. EXPECTED RESULTS
This experiment will demonstrate how the
distribution of electrical resistivity can guide a
soil sample design to determine the soil
properties influencing yam yield.
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15. Thank you for listening !
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