29 Agroforestry

Dr Sunil Mittal

1. Introduction
2. Historical background of Agroforestry
3. Classification of Agroforestry
4. Major Agroforestry practices and their agro ecological adaptability
5. Traditional systems of Agroforestry in India
6. Types of tree species in agroforestry system
7. Areas suitable for agroforestry system
8. Applications of agroforestry
9. Criteria for designing agroforestry
10. Benefits of agroforestry
11. Limitations of agroforestry
12. Issues in agroforestry
13. Major differences between agriculture and agroforestry systems
14. Links of agroforestry system

1. Introduction

Agroforestry is an age old practice that makes use of land system for the production of trees, crops or animals. Agroforestry has the potential to enhance the productivity, maintain the nutrient balance and protect the nature. Agroforestry plays two important roles i.e., service and productive role. Agroforestry systems are dominated by trees to ensure environmental protection and sustainable agriculture. Agroforestry is a practice that is widely characterized by plants and their arrangement, environment and socio-economic functioning. Facets of agroforestry include forestry and tree planting activities. In this practice, farmers are involved and they derive benefits for their daily requirements. Other facets of agroforestry include natural silvipastures, forest grazing and savannas.

Definitions of Agroforestry

The cropping pattern that involves the combining of trees, shrubs, bamboos etc. with animals or herbaceous crops is defined as Agroforestry.

Or

A land use and sustainable management system that enhances agricultural production, and combines forest plants/animals, tree crops and agricultural crops is known as Agroforestry.

Or

Agroforestry is a management practice that involves the incorporation of trees in agricultural landscape and on farms. Agroforestry leads to social, economic and environmental benefits due to diversified and sustainable production.

In general, ecological and socio-economic interactions take place between various components of Agroforestry systems. It means that two or more than two species of plants are present in agroforestry system. The output of agroforestry system will always be two or more than two. Agroforestry cycle takes more than one year for completion and the agroforestry system have much more complexity than monocropping system.

2.  Historical background of Agroforestry

• Around 700 B.C., man changed his living style and started producing food irrespective of food gathering and hunting.
• Co-existence of horticulture with agriculture has been common in India from 500 BC to 1st century A.D.
• Proto-historic chalcolithic periods of civilization provide evidences regarding the cultivation of different varieties of fruits, livestock requirement, cattle breeding and mixed economy in agriculture.
• However in India, pre-Neolithic period showed the happening of plant husbandry under arid climatic zone.
• This practice has been used by the farmers of Central America for a long time. Farmers plant two dozen species of plants in different planes on a small piece of land.
• Slash and Burn was a general custom until middle ages in Europe for the cultivation of food crops.
• Germany and Finland are also practicing this farming system for the last century.

3.  Classification of Agroforestry

Agroforestry system has been classified by the researchers on the basis of structural, functional and socio-economic aspects.

I. Structural basis: The structural classification depends on different components of the agroforestry system and the individual role or function of each component. This type of classification is totally dependent on the type of components and their arrangement.

Figure 1: Schematic representation of structural classification

a)     Nature of the components: Agroforestry systems on the basis of nature of the components include:

1.      Agric-silviculture: plantation of trees and crops

2.      Agri-horticulture: plantation of fruit trees and crops

3.      Agri-silvi horticulture: plantation of trees, fruit trees and crops

4.      Agri-silvipasture: plantation of trees, crops and pasture/animals

5.      Alley cropping: plantation of perennial hedges and crops

6.      Aqua-forestry: combination of trees and fishes

7.      Boundary plantation: plantation of trees on boundaries along with the crops

8.      Block plantation: block of trees and crops

9.      Energy plantation: combination of trees and crops during initial years

10.  Silvi-olericuture: plantation of trees and vegetables

11.  Horti-olericulture: plantation of fruit trees and vegetables.

12.  Horti-pasture: combination of fruit trees and pasture/animals

13.  Silvi-pasture: combination of trees and pasture/animals.

14.  Shelter-belts: combination of trees and crops.

15.  Forage forestry: combination of forage trees and pastures.

16.  Wind –breaks: plantation of trees and crops.

17.  Silvi or Horti-sericulture: combination of trees or fruit trees and sericulture.

18.    Horti-apiculutre: combination of fruit trees and honey bees

19.  Aqua-forestry: combination of trees and fishes

20.  Homestead: multiple combinations of fruit trees, trees, vegetables etc.

b)   Arrangement of components

Spatial arrangement: Agroforestry mixture that results in dense or sparse stands of plants is known as spatial arrangement. The species can be planted at varying widths or zones. Alley cropping (hedge row intercropping) represents common example of zonal pattern.

Temporal arrangement: conventional shifting cultivation cycle is an extreme example of temporal arrangement. When a woody species is planted, then this type of arrangement involves 2-4 years of cropping and fifteen years of fallow cycle. Temporal arrangements are also termed as overlapping, coincident, concomitant, interpolated and separate.

II. Functional basis of classification

This classification is based on the major function of the woody components and it can be productive or protective. Productivity and sustainability are the fundamental attributes of the Agroforestry systems.

Figure 2: Diagrammatic representation of functional classification

a) Productive functions:

• Productive functions of agroforestry system includes :
• Fodder
• Fuel-wood
• Gums, resins, waxes Furniture wood
• Other products

b) Protective functions:

Protective functions of agroforestry systems include:

• Shelter-belt Wind-break
• Soil conservation Soil improvement
• Moisture conservation Shade

III.   Socioeconomic basis of Agroforestry systems

This type of classification considers level of inputs (low or high), management, intensity/scale and commercial goals.

Figure 3: Diagrammatic representation of socio-economic classification

a) Commercial system: Commercial means production of particular product on large scale. The commercialization process may be owned by government, private or corporate. Payment base of labour is either normal or contract base.

Examples include:

• Production of agricultural crops on commercial scale.
• Production of shade tolerant crop plants like tea, cacao and coffee.
• Commercial grazing under timber and pulp plantations.

b)   Intermediate Agroforestry system

This system is known as an intermediate system since it comes in between commercial and subsistence scale of perennial cash crop production.

Examples: Plantation of cacao, coffee, fruit trees and timber species are included in intermediate agroforestry system.

c) Subsistence agroforestry system

This system involves the land use for satisfying basic needs. This system is managed primarily by the owner and his family.

Examples:

• Production of cash crops.
• Traditional shifting cultivation.

4.  Major Agroforestry practices and their agro ecological adaptability

Agroforestry practices have been categorized into three major classes:

a)  Agrisilvicultural

b)  Silvi or silvopastural

c)  Agrosilvopastural or agrisilvipastural

Table 1: Major Agroforestry practices and their agro ecological adaptability

Source: Nair, P. K. R. (1993)

5.  Traditional systems of Agroforestry in India a) Shifting cultivation

This farming system is practised in north-eastern regions having high rainfall. Forest land is cleared by slashing method and then the area is set on fire. Originally the fallow period was 10-20 years, but currently it has been reduced to 2-5 years. The reason for this drastic reduction in fallow period was due to an increase in population pressure. An alternate that can be advocated to shifting cultivation is farming-system approach.

b) Home-gardens/homesteads

An operational system that involves the production of tree crops along with poultry, fish farming and livestock, so as to fulfill the basic requirements of farmers. This practice is an old age one that is particularly practised in coastal states like Tamil Nadu, Assam, Kerala, West Bengal, Andaman and Nicobar islands. This agroforestry system involves a wide range of variation in crops, trees and species. The variation depends upon the holding size, micro-climate and the people living in the homesteads.

The major trees that are grown in Home-gardens are mango, citrus, banana, papaya, and other multipurpose trees. Food crops include sweet potato, elephant yam, cassava, taro and dioscorea. The major components of homesteads are poultry and cattle. Therefore, kazungula, guinea-grass and Guatemala are frequently grown as forages in homesteads.

The intimate mixing of various components of homesteads led to complex interaction among plants, soil, environmental factors and nutrition. The trees that are grown include mango, Grevillea robusta, jack and teak trees.

c) Scattered trees on farm lands

This practice involves the production of scattered trees on farm lands. This practice is an old one and has not undergone any sort of modification over the centuries. E.g., Prosopis cineraria and Faidherbia albida. System complexity and species diversity keeps on increasing with an increase in rainfall. Therefore, humid areas show the proliferation of multi-storeyed home gardens while dry areas show two tired canopy configuration. Trees grown via this practice provide fuel wood, fodder, shade, vegetables, fruits and medicinal products.

d) Trees on farm-boundaries

Sometimes trees that are grown in agricultural fields are also grown along farm-boundaries. For example, Eucalyptus and Populus trees are grown along the boundaries of paddy fields in Punjab and Haryana. Bamboo trees are grown all along the irrigation channels in Sikkim. Plantation of Borassus palm is more frequent in coastal areas of Andhra Pradesh.

e) Wood lots

This practice involves the growth of trees in the form of separate blocks along the agricultural fields. This practice is under continuous expansion since there is shortage of fuel wood. E.g., demand of bamboo poles in orange orchards in Nagpur.

f) Shelter belt

This practice involves the usage of local vegetation or dead wood to build shelter belt so as to check wind velocity. E.g., Leptadenia pyrotechnica and Crotalaria burhia.

g) Trees on rangelands

The most frequent trees that are grown in grazing lands are Prosospis juliflora, P. cineraria, and Acacia nilotica.

h) Aqua-forestry

This practice involves the prawn and fish cultivation in saline water and coconut production along the ponds. These trees produce litter which is used as feed by fish. This practice is more prevalent along Andhra coast.

i) Apiculture with trees

Bees make hive on the trees that are planted along the coastal areas. This practice is more prevalent in the agroforestry system that is rich in floral diversity.

6.  Types of tree species in agroforestry system I. Utilization purpose trees

a)  Fodder cum fuelwood species: Albizia lebbeck, A. procera, A. amara, Sesbania grandifora etc.

b)    Fuel wood  and timber species:  Acacia nelotica, Albizia lebbeck, Azadirachta indica, Dalbergia sissoo, Pongamia pinnata, Melia azadirach, Tectona grandis etc.

c)  Fruit and vegetable species: Mangifera indica, Madhuca indica, Amona reticulate etc.

d)  Softwood and pulpwood species: Bombax cieba, Populus deltoids, Ailanthus tryphysa.

II. Multipurpose trees

a)  Trees grown in good annual rainfall areas Morus alba Populus sp. Sesbania sp. Terminalia sp.

b)  Trees grown in moderate rainfall areas Acacia nilotica Albizia lebbeck Tamarindus indica Eucalyptus sp.

c)  Tress grown in poor rainfall areas Acacia nelotica Acacia catechu Eucalyptus camadulensis Prosospis juliflora

III. Fodder Trees

Fodder provides protein, fats, carbohydrates, minerals, energy and fats to the animals so that they can stay alive.

• Acacia arabica
• Acacia catechu
• Acacia nelotica
• Albizia lebbeck
• Azadirachta indica
• Dalbergia sissoo
• Ficus bengalensis
• Mangifera indica
• Melia azadarach
• Morus alba
• Pongamia pinnata

7.  Areas suitable for agroforestry system

The areas that are suitable for agroforestry include

a)  Field boundaries

b)  Cultivable lands

c)  Cultivable waste

d)  Old fallows

e)  Other areas where there are chances for the incorporation of agroforestry

8. Applications of agroforestry

a)  Resource conservation: Conservation of natural resources like water, plants and lands can be carried out by watershed management. Conservation is an important aspect since it meets the socio-economic needs of human beings. However, degraded land can be conserved or improved by agroforestry practice. It reduces run off, controls erosion, enhances water table, and improves profitability, productivity and soil-moisture conservation.

b) Farming system

Natural resource management can be carried out via agroforestry practice. Therefore, with the change in economy, there is a need to address those technologies that are related to the integrated production of crops, livestock, fisheries and perennials. Diversification can lead to major shift in agricultural production. The shift in agricultural production can be boosted due to urbanization, budding of personal incomes and incorporation of world markets.

c) Biodiversity conservation

India is rich in biodiversity. Innovation in agroforestry contributes towards biodiversity conservation via conservation-development approach.

d) Carbon sequestration

Agroforestry system serves as mitigation strategy and can also be employed for carbon sequestration. Agroforestry provides a cost-effective means through various land use practices for carbon sequestration.

e) Enhancement in soil fertility and structure

Plantation of woody species results in the enhancement and improvement of soil fertility. The reasons for an increase in soil fertility is Leaf litter leads to the addition of organic matter of soil.

Effective utilization of nutrients and efficient nutrient cycling. Nitrogen fixation by micro-organisms Addition of nutrients beyond the nutrient absorbing zone of soil

9.  Criteria for designing agroforestry

The following criteria should be fulfilled for a good agroforestry system:

a)   Sustainability: With an improvement in sustainability of agricultural production system, the conservation goals can be achieved by agroforestry.

b)   Productivity: Productivity with agroforestry can be improved by various ways like:

• Improvement in the yield of associated crops
• Enhancing the labour efficiency
• Diversifying the crop production

c)    Adoptability: Technical design of agroforestry does not matter. The only thing that matters is adoption of that design by the farmers. It clearly means that this technology should fulfil the environmental and social characteristics of the land use system.

10.  Benefits of agroforestry

i. Yield of agricultural products is increased and quality of food is improved.

ii.  Fuel wood, fodder, furniture and other raw materials are produced from trees that fulfill the basic demands of farmers. Moreover, these products can also be put in sale in rural areas.

iii.  Soil productivity potential is protected and improved.

iv.  Recycling of nutrients is permitted due to the decomposition of dead decaying organic matter like fruits, leaves and branches.

v. Soil productivity is enhanced.

vi. Trees help in nitrogen fixation in a form that can be used by the leguminous plants.

vii.Soil erosion is reduced due to planting of trees and thereby soil permeability is also improved.

viii.Agroforestry provides various ecological niches. This results in the improvement of diversity and quality of wildlife.

ix.Agroforestry creates employment and farmers get income. As a result, socio-economic condition is improved in rural areas.

x. Climbing crops get support from agroforestry trees.

xi. Agroforestry is responsible for the development of such type of land use systems that merge modern technologies with traditional experiences. The land use systems thus developed are well-suited with the socio-cultural life of local people involved.

xii. Microclimate can be modified in terms of raising the humidity, minimizing rainfall, reducing wind velocity and extreme temperatures.

xiii. Ecological system developed through agroforestry is more efficient in capturing solar energy and using vertical space.

xiv. Farmers get economic benefits of fuel wood, fruits, honey, fodder, forest and medicinal products.

xv. Plantation of trees in agricultural fields reduces weed eradication costs.

11.  Limitations of Agroforestry system

i. Sometimes shade provided by trees is also responsible for lowering the yield and quality of agricultural crops that have been planted beneath the trees.

ii. Harvesting of trees results in mechanical damage to agricultural crops.

iii. Hand tilling or mechanisation becomes difficult due to the presence of trees.

iv.  More labour is required.

v. Due to the presence of higher number of trees, the moisture content in air also increases. Consequently, bacterial and fungal diseases occur more frequently. Therefore, yield of forage species and food crops get reduced.

vi. During the harvesting of trees, some nutrients are lost. Because nutrients are taken up and stored over longer periods of time by trees.

vii. Trees also compete with crops for moisture, light, space and nutrients. As a result, production of trees as well as crops gets reduced.

12.  Issues in agroforestry

The following reasons are responsible for constraints experienced by small and marginal farmers:

a)   Lack of technical knowledge.

b) Gestation period is longer.

c) Inadequate and delayed availability of seedlings.

d) No knowledge regarding market value.

e) Plantation areas are weakly accessible.

f) Marketing facilities are poor.

g) Farmers do not get assured prices for wood and timber.

h) Certain restrictions put by government on the cutting of trees from farm land.

i) Sometimes premature seedlings are not able to withstand dry spells.

j) People’s participation in agroforestry system is poor.

13. Major differences between agriculture and agroforestry systems

a) Monitoring of agroforestry systems take longer time as compared to agricultural systems.

b) Larger area needs to be established for agroforestry systems. Moreover, variation in crop performance is also expected. However, this is not the case with agricultural system.

14. Links of agroforestry systems

Agroforestry is a multi-locational, multi-disciplinary and multi-functional system. This system is linked to several governmental and non-governmental organizations. These links are essential for co-ordination and to avoid duplication of the work.