Post on 07-Apr-2018
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AGROFORESTRY STRATEGIES FOR LANDDEGRADATION REDUCTION AND
SUSTAINABLE PRODUCTION
BY
FIDELIS AWEVER TISEER (Ph.D)
Department of Biological Sciences,Ahmadu Bello University, Zaria
awtiseer@yahoo.co.uk .
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AGRO FORESTRY STRATEGY FOR LAND DEGRADATION
REDUCTION AND SUSTAINABLE PRODUCTION
INTRODUCTION
Land is defined by FAO (2006), as a delineable area of the
earth’s biosphere, an ecosystem with its soil, water resources (both
terrain and near surface ground reserves), ground surface vegetation,
animals and crops, human settlement pattern and the physical result
of past and present human activities such as terracing, water storage,
drainage structure, infrastructure and buildings.
Land degradation has become an issue the world over. Concerns
over biodiversity decline, water scarcity and human migration and
conflicts are all pointers to one and the same issue. The answers to
these may lie in part from evolution of sustainable production systems,
agro forestry being a credible candidate in the bioresources realm.
Agro forestry as a term is relatively new to the Researchers in
the English sphere, having been adopted from French to English
around 1960. It has since kindled interest in various groups that
research in earth’s sciences with consequently several concepts and
definitions. The practice of agro forestry is however not new
particularly to remote agrarian civilizations that evolved culturally
compliant ways of land management before elitist systematic
approaches.
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To anchor this discourse however, I like to adopt the definition
drawn up by the International Council for Research in Agro Forestry
(ICRAF) with task among which is to set precise definitions of terms
that will guide systematic approaches on the subject. The ICRAF
submitted that “Agro forestry is a collective term for systems
and technologies of land use where perennial woody plants
(Trees, bushes, shrubs, and by assimilation, palms and
bamboos) are deliberately cultivated on ground otherwise
used for crops and/or stock rearing in a spatial or temporal
arrangement, and where there are interactions at once
ecological and economic between the woody plants and the
other components of the system”. The interactions of course could
be positive or negative and may not remain stable in time.
THE ECOLOGICAL CONSEQUENCES OF AGROFORESTRY
SYSTEMS
Declining woody plant cover all over the Nigerian landscape and
particularly on arable lands has elicited or aggravated the;
Decline in soil fertility
Decline in water resources and soil moisture conservation
Increase in soil erosion
Decline in food and feed resources
Decline in biodiversity
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Increase in human migration and communal conflicts
WOODY PLANT COVER AND SOIL FERTILITY
Woody perennials generally have deep root systems which
extract soil nutrients from deep lying soil horizons and deposit these
on the top soil in the form of organic matter through litter droppings.
The mineralization of this litter improves soil structure, releases
mineral elements at the plow zone where annual crop roots can access
them.
The organic matter improves soil aggregates, crumb structure
and soil pore spaces. The effect is percolation of precipitation and
water availability to the root zones of the crops. Fertilizer mobility in
the soil is enhanced and thus improved returns per application results.
Other agroforestry woody trees particularly reduce the amount of
fertilizer requirement per unit area of farm. These are the nitrogen
fixing trees such as Leuceana Leucocephala, Gliricidia sepium and
Milletia thonningii Pterocarpus erinaceus Erythrina senegalensis among
others. Possibly, zonal relatives in this family of trees such as
Lonchocarpus laxiflorus could have the same properties and need to be
investigated. Generally tree roots will prevent or slow down the rate of
soil erosion which wears away top nutrient rich soils.
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While problems of land exhaustion is general of villages in the
South Eastern border of Yankari Game Reserve (Alkaleri Local
Government), soil erosion is particularly serious around
A. Futuk area in the following villages;
Garin Wambal
Wala kerol
Sabon Gari
Alkalerin Kwana
B. Yalo area
Alkalerin Gwana
Digare
C. Mansur Area
Jadan Mansur
Bogga
The indigenes in these villages had ideas compliant with known
agroforestry objective. The woody plants accommodated on their
farms for obvious benefits were;
Scientific Name Hausa Name UsesParkia Clappertoniana Dorowa Soup condimentButrypermum paradoxum Kadanya Mai Kadanya/fruits Afzelia Africana Kawo Edible oil
Cordia Africana Aliliba Sweetner
While these plants have disappeared due to over exploitation for
fuel, artisanal uses and others, the people are willing to reestablish
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them using Taungya method. Other woody species that can help with
the problems are;
Jatropha curcas (Bindazugu); used as a farm demarcation shrub.
A good population of this on the edges of farms helps deter
grazing animals and encourages bees which could be exploited
for honey production.
Scientific Name Hausa Name UsesFaiherbia albida Gawo Animal fodder
Soil nitrogenLonchocarpus laxiflorus Halshen saa/farin sansamii “
Leuceana leucocepha “Gliridia sepuim “Sesbania sesbans “
These are multipurpose woody species that can improve soil
quality and fertility, provide fodder for livestock, fuel for fires and
insurance against wind erosions.
WOODY PLANT COVER AND WATER ECONOMY
A densely woody area causes evaporation of rain water from the
plant surfaces. This increases atmospheric humidity, generating the
cloud that accounts for the next day’s rain. Without the tree cover,
most of the water will enter stream channels or infiltrate resulting in
progressive drying of the air. Also the trees intercept the water from
the rains and release same gradually from stem flow or leaf drips. This
way the soil is much wetter for a longer period in fairly woody areas
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than in bare grounds. Direct evaporation from the ground surface is
also reduced in fairly woody areas. This way plant cover enhances soil
water retention. This makes the accompanying crops enjoy moisture
longer than crops where woody plant have completely been removed.
Deforestation in a watershed could cause other problems such as
stream bank erosion, flooding and disturbance of fish habitats. These
reduce the overall production very significantly. Floods in several parts
of Northern Nigerian are in a way due to massive deforestation in
these regions.
AGROFORESTRY PRACTICES AND SOIL EROSION
Soil is eroded by either rain water or excessive wind.
Agroforestry practices reduce the impact of rain drop, intercept rains
and redistribute rain water in a residual manner. Woody plants on
farms also act as wind breaks. Wind breaks on farms in drier areas can
be achieved by the use of multipurpose trees such as;
Scientific Name Hausa Name UsesTamarindus indica Tsamia Food/feedHyphaene thebiaca Goruba Food/raw material for
making roofs etcMilletia thonningii Tuburku Feeds and N fixationBalanites aegyptica Aduwa Food and feed
Parkia clappertoninia Dorowa Food and feed
The qualities of trees suited for these environments must be;
Drought resistance
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Adaptability to soil
Tolerance of salinity
Resistance of wind, browsing, pest and diseases
Rapid and regular growth
Little development of creeping roots
Production of wood, forage; fruits etc
AGROFORESTRY, FOOD AND FEED PRODUCTION
Multipurpose agroforestry woody plants have cultural medicinal,
food and feed values.
The following woody plants directly provide food for man;
Scientific Name Hausa Name UsesMangifera indiica Mangoro Food/shelterParkia clappertoniana Dorowa Food/feed/shelterMoringa oleifera Zogale Food and medicine
Balanites aegyptiaca Aduwa FoodPhoenix dactylifera Dabino foodBatryspermum paradoxum Kadanya Food and medicine Adansonia digitata Kuka Food and feed
Others such as Faidherbia albida, Acacia Senegal, Leuceana
leucocephala, Gliricidia sepium, milletia thonningii are excellent
browse plants for ruminants in feed stress periods.
Besides these agroforestry trees increase habitat availability for
wild game.
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WOODY PLANTS AND BIODIVERSITY
Plants generally provide habitats for other forms of fauna. This
increases the biodiversity of places that are appreciably wooded. The
consequences are favourable for crops in ways that may not be too
apparent. These include;
Healthy population of pollinators
Integrated farming approaches such as apiculture and crop
husbandry
Rearing of Guinea fowls and Franckolins
WOODY PERENNIALS, CROP PEST AND DESERTIFICATION
Woody plants such as Jatropha curcas act as trap crops which
protect the arable crops from insect damage. Plants in this category
must be unpalatable by the potential pest. This way agroforestry
reduces over dependence on chemical pesticides that are harmful to
the environment.
Desertification is a progressive diminution or destruction of the
biological potentials of the land that leads to desert-like conditions.
This must be distinguished from desertization (desertilized) and should
be recognized as a process that can occur any where. Overall erosion
of biological potentials of the land at the ecosystem level starts with
elimination of perennial woody species on an area and other things
depending on these follow. Consequences include;
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Increased albedo
Increased wind speed/erosion
Removal of top soil
Scurring of young plants by wind blown sand.
Excessive temperatures etc
WOODY PLANTS, HUMAN MIGRATION AND COMMUNITY
CONFLICTS
UNEP (1999), stressed that civil strife, inter communal conflicts
are mainly predicated on land issues. Very frequently there are clashes
between Herdsmen and sedentary farmers due to forage and crop
damages. Even within communities, people who keep ruminants as
secondary enterprises besides farming often have conflicts with others
for crop residue and outright crop damaged. Agroforestry particularly
the use of multipurpose trees on arable farms can incorporate animal
husbandry and crop farming.
Other issues such as human migration are caused by irreversible
soil degradation due to nutrient depletion, erosion and crop failures.
Agroforestry trees can enhance nutrient rejuvenation, soil moisture
retention, soil erosion control hence preserve agricultural soils.
Migration such as this is affecting areas in South Eastern Bauchi State
around the Mansur area.
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TYPES OF AGROFORESTRY
1. Alley cropping – food crops are grown in alleys of fast growing
leguminous trees such as Gliricidia sepium, Leucaeana
leucocophala etc where livestock production is incorporated, it is
called Alley Farming Systems.
The trees may need to be pruned at a point to encourage crop growth.
However where Faidherbia albida (Gawo) is used such a problem does
not exist.
2. Shelter Belt: woody plants are sued as hedge rows to shield
crops from wind throw, scurrying damage from wind borne sand.
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Fig.1: Alley Cropping
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Trees that can be used here include Afzelia africana, Spondias
monbim, Prosopis africana, Parkia clappertoniana, Jatropha curcas.
Hedge rows can also serve as trap plants against pest.
3. Scattered Farm Forestry: a minimum number of 20 – 30
woody trees on a hectare of farm prevents excessive
evaporation from the soil, rejuvenates soil fertility among other
things already mentioned.
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Fig.2: Shelter Belt Hedge Row
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4.
Silvi Pastoral System: Here woody plants in a fuel wood
lot are spaced to accommodate grass/herbaceous pastures on
which ruminants are grazed.
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Fig.3: Scattered Farm Forestry
Fig.4: Silvi Pastoral System
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Trees like Azadiracta indica, Eucalytus camaldulensis etc can be
used. Others are Newbouldia laevis, cassia siamea etc.
5. Agrosilvi Pastoral: This entails allowing livestock on a piece of
land after the crop has been removed. The field held crops and
trees previously. It optimizes the use of a piece of land.
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Fig. 5: Agrosilvi Pastoral