SCHOOL OF GRADUATE STUDIES

CENTER FOR ENVIRONMENTAL SCIENCE

PREPARED ON: ASSESSMENT OF SOIL ORGANIC CARBON

SEQUESTRATION POTENTIAL IN COFFEE FARM AT KAFA ZONE

XELO WOREDA, SNNPR.

BY MELKAMU MEBRATE

SUBMITTED TO: CENTER FOR ENVIRONMENTAL, SCIENCE

ENVIRONMENTAL RESOURCE MANAGEMENT STREAM

ADVISOR: Dr. EYASU ELIAS

NOV, 2013

ADDIS ABABA

SCHOOL OF GRADUATE STUDIES

CENTER FOR ENVIRONMENTAL SCIENCE

PREPARED ON: ASSESSMENT OF SOIL ORGANIC CARBON

SEQUESTRATION POTENTIAL IN COFFEE FARM AT KAFA ZONE

XELO WOREDA, SNNPR.

BY MELKAMU MEBRATE

SUBMITTED TO: CENTER FOR ENVIRONMENTAL, SCIENCE

ENVIRONMENTAL RESOURCE MANAGEMENT STREAM

APPROVED BY ADVISOR

Dr. EYASU ELIAS

____________________

_______________________

SIGNATURE DATE

AbstractSoil, forest and atmosphere are potential carbon sinker in the

terrestrial ecosystem, of which the share of soil is more than

that of forest and atmosphere. Ethiopia is the origin of coffee

(Coffee arabica) where the crop is cultivated as home garden and

forest coffee in the tropical rainforest areas. The total area of

land planted to coffee is estimated at about half million

hectares. The potential of this land use for soil organic carbon

sequestration needs to be evaluated and quantified. In contrast,

very few studies have been conducted on coffee farm soil organic

carbon storage capacity in Ethiopia. The purpose of this study

is, therefore, to assess soil organic carbon sequestration

potential on Asefa Dukamo coffee farm at Kafa zone Xelo woreda

Mixino river, SNNPR and to generate relevant information for

stakeholders on coffee farm soil organic carbon storing capacity

that helps them for climate change mitigation, increased

productivity of soil and improved soil fertility. To achieve

this, a representative coffee farm land on Asefa Dukamo coffee

farm is selected in Xelo woreda and successive soil profiles

will be excavated at different slope positions of the top

sequence. Soil samples will be collected at the coffee farm from

each horizon of the soil profiles to determine soil carbon

concentration, soil texture, type of tillage, soil pH, organic

matter, litter of coffee and bulk density. The collected data

will be analyzed for total organic carbon content using the

Walkley-Black method. For study site delineation and plots

location, GPS will be used. Data on population and agro ecology

of the zone will be collected from secondary resources. The data

in soil laboratory will be calculated and analysed by using SPSS

software and multiple linear regression model will be used to

describe the effects of independent variables on dependent

variables. Then, comparisons will be made on storage potential

with IPCC estimate for the global mitigation potential of C

sequestration in agricultural soils over 100 years and the

result obtained will be aggregated for total potential. Finally,

the conducted results will be presented by employing charts and

graphs.

Key words: soil depth, soil bulk density, pH, soil organicmatter, depth of tillage, litter and soil organic carbon

sequestration potential.

Introduction

The Kyoto Protocol recognizes that net emissions may be reduced

either by decreasing the rate

at which greenhouse gases are emitted to the atmosphere or by

increasing the rate at which greenhouse gases are removed from

the atmosphere through sinks. Agricultural soils are among

the planet’s largest reservoirs of carbon and hold potential for

expanded carbon sequestration,

and thus provide a prospective way of mitigating the increasing

atmospheric concentration of

CO2. Within the context of the Kyoto Protocol and subsequent COP

discussions, a number of

features make CS on agricultural and forestry lands an attractive

strategy for mitigating increases

in atmospheric concentrations of green houses gases.

Article 3.4 of the Kyoto Protocol appears to allow for expansion

of recognized human-induced

sink activities. Recent post Kyoto agreements consider soil sinks

in countries, recognizing the

substantial potential of agricultural and grassland and forest

soils to sequester carbon and the

need for provisions of national credits for the buildup of the

agricultural soil carbon sink. A number of agricultural practices

are known to stimulate the accumulation of additional soil carbon

with soil fertility improvements and positive land productivity

and environmental effects (Michel Robert 2001).

Ethiopia is the origin of coffee (Coffee arabica) where the crop is

cultivated as home garden and forest coffee in the tropical

rainforest areas. The total area of land planted to coffee is

estimated at about half million hectares

(http://www.fas.usda.gov/pecad2/highlights/2002/10/ethiopia/

baseline/Eth_Crop_Production.htm). The potential of this land use

for soil organic carbon sequestration needs to be evaluated and

quantified.

This research will deal with a few researches conducted regarding

soil organic carbon sequestration potential at the coffee farm in

the region; Evaluating the depth of tillage on the

physiochemical properties of the soil such as bulk density,

texture, structure, NPK, OM, pH, among others are pre request to

quantify soil organic carbon sequestration potential of the

area; the need to familiarize methods, techniques and materials

used to assess soil organic carbon sequestration potential of

coffee farm;

To answer the problems of the statement, assessment of the

organic carbon sequestration potential of soil under coffee

plantation in Xelo woreda of Kafa zone, SNNPR is the general

objective with specific objectives such as: To evaluate the

litter accumulation rate from different coffee species as a proxy

measure for soil carbon sequestration potential of coffee soils;

To evaluate the effect of depth of tillage on the physiochemical

properties of the soil such as bulk density, texture, structure,

OM, pH, among others and to provide baseline information for

further study and use of soil organic carbon content of coffee

farm in the study area.

The hypothesis formulated to be tested is: If soil depth, soil

bulk density, pH, soil organic matter, depth of tillage and

litter of coffee crop are quantified, then the soil organic

carbon sequestration potential of coffee farm will be determined.

This research will provide baseline information for stakeholders

on coffee farm soil organic carbon storing capacity that helps

them for climate change mitigation, increased productivity of

soil and improved soil fertility. It will also help to estimate

soil organic carbon sequestration potential of the same farm with

the same dependent variables that can affect the potential to

scaling up throughout the region or the country at large. It will

also be helpful to achieve CRGE goal of the country and carbon

trade to collect foreign hard currency by extrapolating the

result in the same geographic areas with similar farm and farming

system. The study is assumed to boost up the strategy of

country’s food self security by increasing the productivity of

crops with the same soil biophysical characteristics.

Background of the study Soil carbon sequestration, according to Sundermeier et al (2009)

is the process of transferring carbon dioxide from the atmosphere

into the soil through crop residues and other organic solids, and

in a form that is stable and not easily released. Carbon is

primarily stored in the soil as soil organic matter and it is

believed that such carbon sequestration will offset emissions

from the use of fossil fuel and improve soil quality and

agronomic productivity in the long run. Management systems that

generate high biomass to be added to the soil with minimal soil

disturbance, conserve soil and water, improve soil structure, and

enhance soil fauna activity are good sequestration strategies.

Carbon sequestered in the form of soil organic carbon can be used

for potential carbon trading and for sustainable crop production

(Rodolfo O. Ilao1, Eriberto D. Salang2, and Januel P. Floresca3

2010).

According to European Climate Change Programme (ECCP) Final

Report (2013) by citing Huber et al. (2001), Kirchmann and

Andersson ( 2001), soil organic carbon is a major component of

the organic fraction in soil. It positively affects a number of

physical, chemical and biological soil properties and,

consequently, soil functions. An increase of soil organic carbon

enhances aggregate stability for better erosion control and

enhances cation exchange capacity and the buffering capacity for

nutrients and pollutants through variable surface charges of the

humic substances. Soil biological activity favors soil fertility,

resilience and often pest control. Macro fauna enhances soil

aeration and infiltration capacity by the creation of continuous

macro pores connecting the topsoil with the subsoil.

accordingly, soil organic carbon maintains important soil

functions with regard to habitat, biological diversity, soil

fertility, crop production potential, erosion control, water

retention, matter exchange between soil, atmosphere, and

groundwater, and the filtering, buffering and transforming

capacity.

Different soils have different capabilities to sequester carbon.

The potential for sequestration is higher in soils with low

organic carbon content and decreases in soils with higher organic

carbon content. The quantity and quality of soil C inputs change

across agricultural systems and agricultural crops. Litter

quantity and quality in agricultural systems depend on the crops

cultivated and on the inputs to production (e.g., fertilizers,

irrigation, and soil tillage).

According to Rodolfo O. Ilao1, Eriberto D. Salang2, and Januel P.

Floresca3 (2010) citing Salang (2010) in two selected soil series

(Faraon and Adtuyon) of Zamboanga Peninsula, reviewed that the

evaluated soil carbon sequestration under different tillage and

cropping systems, types of vegetation and soil organic level

indicated different amount of soil carbon stock. Estimates of

carbon sequestration potentials of soils could be evaluated

through chemical and physical properties by quantitative

analysis.

Soil carbon stocks (tones C/ha) can be calculated based on carbon

concentration (%) and bulk density (BD) for each mean depth of

soil unit was described in Jones (2007) as cited by Mae Leavitt

(2013).

Statement of the problems

There is a few researches conducted regarding soil organic carbon

sequestration potential at the coffee farm in the region;

Evaluating the depth of tillage on the physiochemical properties

of the soil such as bulk density, texture, structure, OM, pH,

among others are pre request to quantify soil organic carbon

sequestration potential of the area;

Evaluating the maximum SOC sequestration potential of coffee

farm;

Determining soil organic carbon are sequestered and functions of

it in the soil at coffee farm;

Determining most pronouncing factors for SOC sequestration

potential of coffee farm;

There is the need to familiarize methods, techniques and

materials used to assess soil organic carbon sequestration

potential of coffee farm;

HypothesisIf soil depth, soil bulk density, pH, soil organic matter, depth

of tillage and litter of coffee crop are quantified, then the

soil organic carbon sequestration potential of coffee farm will

be determined.

Alternative hypothesis( optional) Changes in soil depth, soil bulk density, pH, soil organic

matter, depth of tillage and litter of coffee crop

( independent variables) will have effects on soil organic

carbon sequestration potential of coffee farm ( dependent

variable). Or Changes in soil depth, soil bulk density, pH,

soil organic matter, depth of tillage and litter of coffee

crop ( independent variables) will have no effects on soil

organic carbon sequestration potential of coffee farm

( dependent variable).

The significance of the studyThis research will provide baseline information for stakeholders

on coffee farm soil organic carbon storing capacity that helps

them for climate change mitigation, increased productivity of

soil and improved soil fertility. It will also help to estimate

soil organic carbon sequestration potential of the same farm with

the same dependent variables that can affect the potential to

scaling up throughout the region or the country at large. It will

also be helpful to achieve CRGE goal of the country and carbon

trade to collect foreign hard currency by extrapolating the

result in the same geographic areas with similar farm and farming

system.

It is also assumed to boost up the strategy of country’s food

self security by increasing the productivity of crops with

improved soil fertility.

LimitationsThis research will be encountered with problems such as clear

methodology for data collection and data analysis, quantity and

quality of laboratory equipments and detergents, budget and time.

To overcome these limitations, the researcher will work closely

with advisor and the Walkley-Black method will be used to manage

the problem encountered during data collection and data analysis.

To solve time and budget, data collection and data analysis will

start as early as possible. Shortage of finance to conduct the

research, sponsors will searched with the advisor.

General objective The general objective of this study is to assess the organic

carbon sequestration potential of soil under coffee plantation

in Xelo woreda at Kafa zone, SNNPR.

Specific objectives To evaluate the litter accumulation rate from different coffee

species as a proxy measure for soil carbon sequestration

potential of coffee soils ;

To evaluate the effect of depth of tillage on the

physiochemical properties of the soil such as bulk density,

texture, structure, OM, pH, among others;

To determine soil organic carbon are sequestered and functions

of it in the soil at coffee farm;

To determine most pronouncing factors for SOC sequestration

potential of coffee farm;

To provide baseline information for stakeholders on coffee

farm soil organic carbon storing capacity that helps them for

climate change mitigation, increased productivity of soil and

improved soil fertility.

Materials and methods

Description of study sites

According to Abebayehu Aticho (2013), Kafa Zone is located in

the Southern Nation, Nationalities and People’s Regional Stat of

the most ethnically and linguistically diverse region of

Ethiopia. Bonga is the administrative town of Kafa Zone which is

located at 450km away from Addis Ababa. The Zone is mostly

covered with evergreen montane cloud forest and is part of the

Eastern Afromontane Biodiversity Hotspot. The Zone has a total

land area of 10602.7 square kilometer of which 23.1% is

cultivated, 31.54% is forestland, 6.03% grazing land, 24.9%

cultivable land and the remaining 14.43% is uncultivable (swampy

and wetlands).

According to 2007 census, the total population of the Zone is

858,600 with population density of 90 persons per kilometer

square. Its altitude is range from 500 to 3500 m.a.s.l with the

mean annual rain fall and temperature of 1001 - 2200mm and 10.1

to 27.5°C, respectively. Xelo woreda is one of the woreda’s in

Kefa zone, SNNPR. Asefa Dukamo coffee farm around Mixino river is

found in the Xelo woreda and 25 km far from the Bonga town. The

research will be conducted on SOC at this coffee farm.

Sample collection

Soil sample will be collected at Kefa zone Xelo woreda around

Mixino river, SNNPR from Asefa Dukamo coffee farm within 103

ha. Out of 103 ha of coffee farm, 20 sampling plots will be

identified and designed at 0.25m2 square base using simple

random method. Soil sample will be collected at 0-30 cm or

further subdivide it into 0–10 and 10–30 cm layers from each

plots in dry season and packed in plastic bags. Study site,

plots locations and measurement will be performed using GPS and

tape meter.

Sample processing

The collected soil from all sampling plots will be refined by

using the hydrometer method to categorize them based on textures

(e.g. silt, sand and clay). then, dried in oven in the laboratory

of Addis Ababa university. The dried soil will be sieved through

2 mm mesh and used for stone correction. Plant residues on the

soil surface ( e.g. leaves, manure, or crop residue) are not

considered SOM and will be removed from soil samples by sieving

through a 2 mm wire mesh ( Gregory W. McCarty1*, James B.

ReevesIII2, Russell Yost3, Paul C. Doraiswamy1 and Mamadou

Doumbia4 , 2010).

Data analysis

According to Tammy Umholtzoil 2013, organic matter (SOM) is the

organic component of soil, consisting of three primary parts

including small (fresh) plant residues and small living soil

organisms, decomposing (active) organic matter, and stable

organic matter (humus). Components vary in proportion and have

many intermediate stages. Plant residues on the soil surface such

as leaves, manure, or crop residue are not considered SOM and are

usually removed from soil samples by sieving through a 2 mm wire

mesh before analysis. Soil organic matter typically is measured

in a lab and therefore, Addis Ababa University laboratory will

provides soil color chart to estimate the amount of SOM among

soil textures.

According to P. HALUSCHAK, 2006, soil pH is a measure of the

activity of ionized H in the soil solution. Soil pH is an

indicative measurement of the chemical properties of a soil. The

pH of a solution is defined as the negative logarithm to the base

10 of the H+ activity. Therefore, it will be calculated as pH = -

log [H+].

According to Tom Fermanian in (2010), texture, bulk and particle

density are physical properties of soils that control many

important soil processes. Texture affects the total water holding

capacity of the soil, percentage of plant-available water, cation

exchange capacity and many other soil properties and processes.

Bulk and particle density are related to soil porosity, degree of

compaction, movement of air and water into and through the soil,

ease of root growth as well as other properties. The

determination of the size distribution of soil particles is known

as mechanical or particle size analysis. Soil texture is the

composition of the soil particles expressed as the percent of

particles in the sand, silt, and clay, therefore, size separates

after organic matter, carbonates, and iron and manganese oxides

and other cementing or binding agents are removed.

The hydrometer method is based on the change of density of a soil

and water suspension upon the settling of the soil particles.

Stokes' Law is used to predict the settling times for various

sized particles. Stokes' law states that the rate which particles

fall in a viscous medium (water) is governed by the radius of the

particles and the force due to gravity. A special hydrometer,

calibrated in terms of the grams of soil suspended, is used to

measure density. Therefore, texture, bulk and particle density

will be determined using this methods.

The soil organic carbon storage will be measured from oxidizable

organic carbon by a modified Walkely-Black method for 20 soil

sample plots as described by MISUN KANG in 2002.

Statistical analysisStatistical Package for the Social Sciences(SPSS) version 16 will

be used to analyze soil data. Multiple linear regression model

will be used to describe the effects of independent variables on

dependent variables.

Appendices

Time lineNo.

Activity Unit Date

1. Proposal preparation Time Sep 1,2013 -Oct 30, 2013

2. Proposal approval Time Nov 2, 20133. Proposal defense Time Nov 15, 2013Total time 62 daysSample collection

4 Site preparation for Samplecollection

Time Dec 1-15,2013

5 Sample collection Time Dec 16,2013-Jan 30, 2013

6 Data organization Time Feb 5-25, 2013Total time for sample collection and organization80 days

7 Laboratorial analysis Time Feb 30, 2013-

Mar 30, 2013Total time for laboratorial analysis30 days8 Data analysis and

interpretationTime Apr 1,2013-

May 10,2013Total time for data analysis and interpretation40 days9 Paper organization Time May 11, 2013-

Jun 19, 2013Total time for Paper organization30 days10 Advisor approval and

collectionTime Jun 30

Total time for Advisor approval and collection11 days11 Final research defense Time Jul 10, 2013Total time for final research defense1 day

Total time for whole activities243 days or 8.1 months

Budget breakdown No. Items Quantit

yUnit Unit price Total

priceData collection materials

1 sharpshooter shovel a long narrow-bladed shovel

1 50 50

2 soil probe (smaller diameter) for extracting soil cores

1 50 50

3 hammer probe for sampling more difficult soils

2 150 300

4 bulk density corer short section of 3-inchpipe, outside beveled on one end

1 100 100

5 hammer, wood block for tappingin bulk density corer

1 100 100

6 140 cc syringe, plastic wrap for measuring clod volume

6 50 300

7 6-inch steel rule, metric for measuring bulk density cores

5 30 150

8 2-mm sieve for sample prep and bulk density clodmethod

2 150 300

9 plastic or canvassheets for pilingdirt from holes

25 50 125

10 plastic containers for

25 50 125

collecting and mixing samples

11 serrated knife and sharpened putty knife for cutting soil

2 100 200

12 sharp pointing trowel for shaping and excavation

2 250 500

13 sample bags quartziplocs work well

25 50 125

14 permanent markersfor labeling sample bags

25 25 125

15 camera for photographing plots

1 8500 8500

16 GPS receiver for mapping plots

1 4500 4500

17 sighting compass/inclinometer for laying out plots

1 2500 2500

18 meter sticks for measuring cores and laying out plots

2 100 200

19 200-foot or 50-meter tape for laying out plots and fixing location

2 100 200

20 clipboard and data forms for recording data

6 100 600

21 Beam balance 1 2500 2500Laboratory equipments and detergents

22 Laboratoryequipments anddetergents costs

50000

Per dam and transport 23 Enumerators’ cost 6 Birr 1500 900024 Accommodation

cost30 400 12000

25 Transport cost 2 Trip 3000 6000Sub total

99000Contingency 10% 9900

Total108900

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