FARM FORESTRY. Agro-forestry

Transcription

1 FARM FORESTRY Agro-forestry Dr. Salil K. Tewari Professor Agro-forestry Project Dept. of Genetics and Plant Breeding College of Agriculture G.B. Pant University of Agriculture and Technology Pantnagar CONTENTS Introduction History of Agroforestry in India Traditional Agroforestry Systems in India Agroforestry in Recent Past Scope of Agroforestry Features of Agroforestry Significance of Agroforestry Benefits of Agroforestry Classification of Agroforestry System Tree-Crop Interactions Forest Farming Limitations of Agroforestry Agroforestry Extension ( ) Keywords 1

2 Introduction Trees play an important role in ecosystem in all terrestrials and provide a range of products and services to rural and urban people. As natural vegetation is cut for agriculture and other types of development, the benefits that trees provide are best sustained by integrating trees into agricultural system a practice known as agroforestry. Farmers have practiced agroforestry since ancient times. Agroforestry focuses on the wide range of trees grown on farms and other rural areas. Among these Fig.1:Rice intercropped with salix are fertilizer trees for land regeneration, soil health and food security; fruit trees for nutrition; fodder trees for livestock; timber and energy trees for shelter and fuel wood; medicinal trees to cure diseases and trees for minor products viz. gums, resins or latex products. Many of these trees are multipurpose, providing a range of benefits. According to the 2001 report of the Forest Survey of India, the forest cover in the country is 675,538 sq.km, constituting 20.55% of its total geographical area. Out of this, dense forest constitutes 2.68% and open forest 7.87%. The forest cover in the hilly districts is only 38.34% compared with the desired 66% area. The National Agriculture Policy (2000) emphasized the role of agroforestry for efficient nutrient cycling, nitrogen fixation, organic matter addition and for improving drainage and underlining the need for diversification by promoting integrated and holistic development of rainfed areas on watershed basis through involvement of community to augment biomass production through agroforestry and farm forestry. The Task Force on Greening India for Livelihood Security and Sustainable Development of Planning Commission (2001) has also recommended that for sustainable agriculture, agroforestry may he introduced over an area of 14 million ha out of 46 m ha irrigated areas that are degrading due to soil erosion, water-logging and salinization. For integrated and holistic development of rainfed areas, agroforestry is to be practiced over an area of 14 million ha out of 96 m ha. This all will, besides ensuring ecological and economic development provides livelihood support to about 350 million people. The practice of agroforestry can help in achieving these targets. Therefore in the quest of optimizing productivity, the multi tier system came into existence. Gap of demand and supply of forest produce in India is widening and forests are unable to fulfill the demand. Agroforestry can play an important role in filling this gap and conservation of natural resources MOEF Table 1: Demand and supply of different tree produce in India Timber (m.m 3 ) Fuel (m.tones) Industrial wood Green fodder (m.tonnes) Dry fodder (m.tonnes) Demand Forest Supply Farm forest total Deficit The origin of agroforestry practices, i.e. growing trees with food crops and grasses, is believed to have been during Vedic era (Ancient period, 1000 BC) the agroforestry as a science is introduced only recently. The systematic research in agroforestry geared up after the establishment of the 2

3 International Council for Research in Agroforestry (lcraf) in 1977, which was renamed in 1991 as the International Centre for Research in Agroforestry. During , ICRAF adopted a new brand name "World Agroforestry Centre", to more fully reflect their (ICRAF's) global reach and also their more balanced research and development agenda; however their legal name "International Centre for Research in Agroforestry" will remain unchanged. In India, organized research in agroforestry was initiated in 1983 by the establishment of All India Coordinated Research Project on Agroforestry by ICAR at 20 centres and later establishment of the National Research Centre for Agroforestry at Jhansi in At present 39 centres of agroforestry are working in the country. The process of system evolution can be still observed in the natural forests through settled agriculture, animal husbandry and organized forestry with the adoption of variety of land use practices where tree is one of the components. Agroforestry systems have been the target of scientific enquiry and analysis and thus have been defined by many in different ways. Definition of Agroforestry Agro forestry, the word coined in early seventies, has made its place in all the developed and the developing countries of the world. A few definitions of agroforestry are as under: "A sustainable management system for land that increases overall production, combines agricultural crops, tree crops and forest plants and/or animals simultaneously/or sequentially and applies management practices that are compatible with cultural patterns of local population". "Agroforestry is a collective name for land-use systems and technologies in which woody perennials including trees, shrubs, bamboos etc. are deliberately combined on the same landmanagement unit with herbaceous crops or animals either in some form of spatial arrangement or temporal sequence." "Agroforestry is a land-use that involves deliberate retention, introduction, or mixture of trees or other woody perennials in crop/animal production field to benefit from the resultant ecological and economical interactions". "Agroforestry is a dynamic, ecologically based, natural resource management practice that, through the integration of trees on farms and in the agricultural landscape, diversifies and sustains production for increased social, economic and environmental benefits". In agroforestry systems there are both ecological and socio-economic interactions between different components. This implies that Agroforestry normally involves two or more species of plants (or plants and animals), at least one of which is a woody perennial; An agroforestry system always has two or more outputs; The cycle of an agroforestry system is always more than one year; and even the simplest agroforestry system is structurally, functionally, and socio-economically more complex than a mono-cropping system. It needs to be clearly understood that specifying the existence of spatial-temporal arrangements among components does not help in defining agroforestry, but its value lies in classifying agroforestry examples. Multiple cropping as opposed to multiple uses is a necessary condition to 3

4 agroforestry. Production diversification is not exclusive to agroforestry and does not help in defining agroforestry. The sole existence of economical interactions among the components is not a sufficient condition to define agroforestry; biological interactions must be present. Similarly the term significant interactions among the components can not be used objectively in defining agroforestry, and its use should be avoided. The presence of animal is not essential to agroforestry. Agroforestry implies management of at least one plant species for forage, an annual or perennial crop production. Once appropriate time limits are imposed on the system, time sequences involving at least two plant species with at least one woody perennial must be considered agroforestry. On the basis of this analysis, the final definition of agroforestry could be: "Agroforestry is a form of multiple cropping which satisfies three basic conditions (i) there exists at least two plant species that interact biologically, (ii) at least one of the plant species is a woody perennial and (iii) at least one of the plant species is managed for forage, annual or perennial crop production." It shows that agroforestry is a new name for a set of old practices. In simple terms agroforestry is "an efficient land-use system where trees or shrubs are grown with arable crops, seeking positive interactions in enhancing productivity on the sustainable basis". Agroforestry combines agriculture and forestry technologies to create more integrated, diverse, productive, profitable, healthy and sustainable landuse systems. The most important agroforestry practices are windbreaks, riparian forest buffers, alley cropping, silvopasture and forest farming. Agroforestry is a "social forestry" - its purpose is sustainable development. Practices are focused on meeting the economic, environmental and social Fig. 2:Musterd with Cassia fistula needs of people on their private lands. At the farm level, agroforestry is a set of practices that provide strong economic and conservation incentives for landowner adoption. Incorporated into watersheds and landscapes, agroforestry practices help to attain community/society goals for more diverse, healthy and sustainable land-use systems. History of Agroforestry in India In about 700 BC, man changed from a system of hunting and food gathering to food production. Shifting cultivation in India is prehistoric and partly a response to agroecological conditions in the region. Horticulture as co-existent with agriculture is found to have been prevalent in India from early historic period (500 BC to I st century An) when a certain amount of share in garden crops started to have been enjoyed by the king for providing irrigation. Some stray references occur in different texts of the Vedic literature. The cultivation of date-palm, banana pomegranate, coconut, jujube, aonla, bael, lemon and many varieties of other fruits and requirement of livestock in agriculture and mixed economy of agriculture and cattle-breeding may be traced in proto-history chalcolithic periods of civilization. But in India, the plant husbandry (intentional sowing or planting for production of desirable plants or plant domestication) happened to start under progressively arid climatic zone from about pre-neolithic 4

5 period. The role of many common trees such as khejri or sami (Prosopis cineraria), aswattha (Ficus religiosa), palasa (Butea monosperma) and varana (Crataeva roxburghii) in Indian folklife has been mentioned in ancient literature of Rig Veda, Atharva Veda and other ancient scriptures. Traditional agroforestry systems manifest rural people's knowledge and methods to benefit from complimentary uses of annuals and woody perennials on the sustained basis. It also indicates that farmers have a closer association with trees than any other social group and promoters of forests. In central America it has been a traditional practice for a long time for farmers to plant about two dozen species on a small piece of land configuring them in different planes. In Europe, until middle ages, it was the general custom to clear fell, degraded forests, burn slash, cultivate food crops for varying periods on cleared area and plant trees before or along with, or after sowing agricultural crops. This farming system was widely practised in Finland up to the end of the last century and in a few areas in Germany as late as the 1920s. In certain far-east countries practice, people clear forest for agricultural use- they deliberately spared certain trees which by the end of the rice-growing season provided partial canopy of new foliage to prevent excessive exposure of soil to sun. The farmers and land owners in different parts of the country integrate a variety of woody perennials in their crop and livestock production fields depending upon the agroclimates and local needs. Most of these practices are, however very location specific and information on these are mostly anecdotal. Therefore, their benefits have remained vastly under exploited to other potential sites. It has now been well-recognized that agroforestry can address some of the major land-use problems of rainfed and irrigated farming systems in India, and that a great deal can be accomplished by improving indigenous systems. With the current interests in agroforestry worldwide, attempts are being made in India to introduce agroforestry techniques using indigenous and exotic multipurpose and nitrogen-fixing woody perennials. Traditional Agroforestry Systems in India Agroforestry is widespread in all ecological and geographical regions of India. The systems vary enormously in their structural complexity and species diversity, their productive and protective attributes and their socio-economic dimensions. They range from apparently simple forms of shifting cultivation to complex home-gardens: from systems involving sparse stands of trees on farm lands (e.g. Prosopis cineraria khejri tree - in arid regions of western India) to high-density complex multistoried homesteads of humid lowlands: from systems in which trees play a predominantly 'service' role (e.g. shelter belts) to those in which they provide main salable products (e.g. intercropping with plantation crops). Most of these are anecdotal but in some enough research efforts have been carried out in recent times. Shifting cultivation (slash and burn system):it refers to farming system in north-eastern high rainfall areas in which land under natural vegetation (usually forests) is cleared by slash and burn method cropped with common arable crops for a few years and then left unattended when natural vegetation regenerates. Traditionally the fallow period is years but in recent times it is reduced to 2-5 years in many areas. Due to the increasing trends of population pressure, the fallow period is drastically reduced and system has degenerated causing serious soil erosion depleting soil fertility resulting to low productivity. In north-eastern India many annual and perennial crops with diverse growth habits are being grown. 5

6 At times annual crops such as potato, rice, maize and ginger are grown in monoculture or mixed culture along with Pinus kesiya. Another important attribute of the system is secondary succession of vegetation during fallow period. The tree species which may be considered suitable for afforestation of fallow areas or to intercrop with arable crops must be fast growing preferably nitrogen-fixing and must efficiently recycle available nutrients within the system shortening time required to restore fertility. These may include species of Acacia, Albizia, Alnus, Casuarina, Erythrina, Faidherbia, Gliricidia. Inga, Leucaena, Parkinsonia, Pilhecellobiuin. Prosopis, Robinia and Sesbania. Thus intercropping under or between fast-growing trees in a fallow phase is one of the approaches while finding alternative to shifting cultivation. A farming-system approach based on the watershed management has been advocated as an alternative to shifting cultivation. Taungya system: The Taungya system is like an organized and systematically managed shifting cultivation. The word is reported to have originated in Myanmar (Burma) and tauang means hill, ya means cultivation. i,e. hill cultivation. It involves cultivation of crops in forests or forest trees in crop-fields and was introduced to Chittagong and Bengal areas in colonial India in Later it had spread throughout Asia, Africa and Latin. The taungya (taung = hill, ya = cultivation) is a Burmese word coined in Burma in the 1850s. The taungya system was introduced into India by Brandis in 1890 and the first taungya plantations were raised in 1896 in North Pradesh and the north-eastern hill region. In southern India, the system is called kumari. It is practiced in areas with an assured annual rainfall of over mm. Home-gardens/homesteads Cultivation: A homestead is an operational farm unit in which a number of crops including tree crops are grown with livestock, poultry and/or fish production, mainly for the purpose of meeting the routine basic needs of the farmer. It is an old-age practice in coastal states particularly in Kerala, Tripura, Assam, North-eastern states and parts of West Bengal and Andaman and Nicobar Islands. Although the home-gardens appear to be a mixture of trees, shrubs and herbs, a certain general pattern seems to exist. There is wide variation in the intensity of trees, species and crops based on the size of holding, needs of the people residing in homesteads and micro-climate. Coconut, arecanut, guava, mango, citrus, tamarind, jack-fruit, papaya, banana, moringa, sesbania, custardapple and many multipurpose trees are the major trees found grown in home-gardens. Domestic animals and poultry are the main components of homesteads; therefore, sometimes forages like stylo (Slylosanthes guianensis / S. hamata), guinea-grass, Guatemala, napier and others are also grown frequently. The components are so intimately mixed in horizontal and vertical strata as well as in time that a complex interaction exists among soil, plants, other aboveground and below ground components, nutrition and environmental factors. There is critical competition both for light and nutrition. The holder chooses his crops and crop combinations based on his wisdom, needs and perceptions acquired over generations of experience. Many multipurpose trees having productive and protective functions are integrated into the system in different spatial and temporal arrangements. Most of these trees closely interact with agricultural crops when grown. These trees include teak (Tectona grandis), jack-trees (Artocarpus spp.), Casuarina equisetifolia, Mangifera india, Ceiba pentendra, Leucaena 6

7 leucocephala, Grevillea robusta, Bambusa arundinacea, Erythrina variegata and Gliricidia sepium (both good support to black pepper). Thespesia populnea is common in low lying homesteads and the wood is commonly used for agricultural implements. Mangroves form an essential part of homesteads of backwater areas in lowlands. These are commonly used as fuelwood. Coconut and pandanus (Pandanus tectorius) can be commonly seen near canals and backwaters. Palmyrah palm (Borassus flabellifer) is common multipurpose palm in coastal Andhra Pradesh. Fish and shrimp culture in backwater channels and in association with mangroves is the main activity in homestead. Thus, multitude of crop species in the homesteads helps to satisfy primary needs of the farmer such as food, fuel, fodder, timber and cash. This in spite of high intensity of cropping also helps to conserve fertility by nutrient cycling or organic manuring or mulching and increased microbial activity in the rhizosphere of crops. Among social benefits are-high family labour utilization and risk minimization. This system also helps in checking soil erosion (due to high intensity of vegetation cover), environmental health and conserving biodiversity. Plantation based Agroforestry systems: Modern commercial plantation crops like rubber, coffee, poplar, eucalypts and oilpalm represent a well-managed and profitable stable land-use activity in tropics. The scope for integrative practices involving plant associations in these commercial plantations is limited, except during the early phases of plantation when some intercropping is feasible, the commercial production of these crops is aimed at having a single commodity. Some of the plantation crops like coconut, palms have been cultivated since very early times but their economic yield remained low. However, the research attention and commercial yields of these crops have increased substantially. Contrary to common belief - a substantial proportion of tropical plantation crops is grown by small farmers. Most of the coconut production in India, and other countries comes from small holdings, in which coconut-palm is integrated with a large number of annual and perennial crops like clove, cardamom, coffee, cacao, cassava, yams, fodder grasses and legumes. Grazing under coconut and cashew nut is also common. In India, small holders grow cashew-trees (in wider space) with other crops. In the last two decades, most of the data have come from coconut-based systems in India, related to intercropping under coconuts, integrated mixed farming in small holdings, grazing under coconuts, factors favoring intensification of land use with coconuts and multi-storey treegardens. Important cereals grown with coconut include rice, finger millet and maize: pulses such as pigeon pea, green gram, black gram, cowpea, soybean, oilseed crop such as groundnut; root crops such as sweet-potato, yams, elephant foot-yam and taro: spices and condiments such as ginger, turmeric, cinnamon, clove, chilies and black pepper; fruits like pineapple, mango, banana and papaya; cash crops such as cotton and sugarcane, plantation crops such as areca nut, cacao and coffee, Many trees such as species of Erythrina, Ceiba, and Cordia find a place in the system. Scattered trees on farm lands: The practice of growing agricultural crops under scattered trees on farm lands is old and does not seem to have changed for centuries. Though world-wide list of such trees is long, some of them have received more attention than others e.g. Prosopis cinaria in north-western India and Poplars in north India. The species diversity in these systems is very 7

8 much related to ecology. With increase in rainfall, the species diversity and system complexity increases. Thus, there is a proliferation of more diverse multistoried home-gardens in humid areas and less diverse, two tiered canopy of configurations (trees + crop) in drier areas. Trees are grown scattered in agricultural fields for many uses such as shade, fodder, fuel wood, fruit, vegetables and medicinal uses. Some of the practices are very extensive and highly developed in India. For example growing Prosopis cilleraria and Zizuphus in arid areas; Acacia nilotica in Indo- Gangetic plains; Grevia optiva and other tree species in hills of Uttarakhand and HP; Eucalyptus globulus in southern hills of Tamil Nadu and Brossus flabellifer in peninsular coastal regions. There are strong convictions for the acceptance of these trees on agricultural fields since time immemorial. Farmers retain trees of Acacia nilotica, Acacia catechu, Dalbergia sissoo. Mangifea indica,. Zizuphus mauritiana and Gmelina arborea are preferred in Gujarat with crops. Farmers in subhumid terai region of Uttarakhand and Uttar Pradesh prefer Dalbergia sisoo, Syzygium cumnii and Trewia nudiflora. In Bihar, Dalbergia sissoo, Litchi chinensis and Mango are frequently grown on fields. Every part of the palm is used by common man: the leaves for thatching, trunk as pillar or timber, fruit is roasted and consumed, the radicle of germinating seeds is roasted, a beverage (alcohol) is extracted from spadix, which is also used to prepare jaggery and vinegar. Other most common trees found on farmers' fields are Azadirachta indica, Moringa oleifera, Tamarindus indica, Ceiba pentandra. Anacardiuln occidental, Cocos nuciferaand fruits like banana, custard-apple, guava and pomegranate. Trees on farm-boundaries: Trees grown in agricultural fields are also often and usually grown on farmboundaries. In northern parts of India, particularly in Haryana and Punjab Eucalypts and Populus are commonly grown along the field boundaries or bunds of paddy fields; other trees which are found grown as boundary plantations or live hedge include-. Dalbergia sissoo and Prosopis juliflora. Farmerrs of Sikkim, grow bamboo (Dendrocalamus, Bambusa) all along the irrigation channels. In coastal areas of Andhra Pradesh, Borassus is the most frequent palm. In Andamans, farmers grow Gliricidia sepium, Jatropha spp, Ficus, Ceiba pentandra, Vitex trifolia and Erythina variegata as livehedges. At many places succulents like Agave and many cactoids are grown as common live-fence. Many of the boundary plantations also help as shelter-belts and wind-breaks, particularly in fruit orchards. In Bihar, Dalbergia sissoo and Wendlandia exserta are most common boundary plantations. Wood lots: In many parts, farmers grow trees in separate blocks as wood-lots along with agricultural fields. Now the practice is expanding fast due to shortage of fuel-wood and demand of poles or pulp-wood in industry. For example, bamboo poles are in great demand for orange orchards in Nagpur area and Eucalvptus and Poplars for match industries. These days wood-lots are being raised mostly on large farms due to increase of labour costs and labour management, lack of irrigation and risk of crop investments. Wood-lots of Casuarina, bamboo, poplar, Eucalyptus, Leucaena leucocephala, red sandal (Pterocarpus santalinus) and Dalbergia sissoo have become popular in many parts of the country. 8

9 Systems for soil conservation or amelioration: About 150 million ha of land in India is subject to serious wind and water erosion, of which 69 million ha are critically affected. About 4 million ha is suffering from degradation due to ravines and gullies 11.3 M ha as riverian land. Coastal sandy areas and steeply sloping lands and more than 9 million ha is salt affected. The deep and narrow gullies are best controlled by putting them to permanent vegetation after closure to grazing. Afforestation with suitable tree species like Acacia nilotica, Azadirachta indica, Butea moonosperma. Prosopis juliflora, Dalbergia sissoo, Tectona grandis, Bambulsa spp. and Dendrocalamus and other adaptable species such as grasses like Dichanthium annulatum, Bothriochloa pertusa, Cynodon dactylon and Sehima nervosum will help in stabilizing ravines and gullies and checking their spread. In recent times, due to increase in population pressure these wood-lots have shrunk at a fast rate. Shelter belt: Arid regions witness very high wind velocity throughout the year. Farmers build shelter-belt (kana bundi) by either small dead wood or local vegetation to check wind velocity within safer limits. Crotolaria burhia, Leptadenia pyrotechnica and Aerva pseudotomentosa bushes are planted in m a part rows across the wind direction. Between the lines of these shrubs grasses such as Cenchrus ciliaris, C. setigerus, Lasiurus sinicus etc are planted on leeward side of each break. This permanent vegetation helps accumulate sand near them which is again spread in the field. This also helps increase crop yields along the lines. Trees on rangelands: As pointed out above, Salvadora oleoides, Capparis decidua. Acacia nilotica, A. leucophloea. P. cineraria, and now Prosopis juliflora also are most frequent trees on common community grazing lands. In tropics coconut is most common tree on pasture lands. Cattle raising usually involves grazing on these pastures. In some cases special fodder plants including legumes are also cultivated. Agroforestry in Recent Past Especially during the last 3-5 centuries spectacular improvements have been made in tree plantation. The most important agroforestry practice is known from the Kangeyam tract of Tamil Nadu, where Acacia leucophloea + Cenchrus setigerus in silvi-pasture system was perfected. Similarly, in ravines of Yamuna and Chambal, trees, shrubs and bamboos with grasses were planted for rearing milk-producing Jamunapari breed of goats and sheep. Scattered trees with khejri or mehndi in association with Fig. 3: Systematic plantation of Tree Species bajra, jowar and chillies were grown in the semi-arid area of Tamil Nadu. Tree plantation continued as demarcation and control against wind erosion throughout the country. Plantation of khejri trees for various uses on on-farm was a common practice in Rajasthan. In coastal areas, Casuarina equisetifolia and other trees were grown in association with crops on farm lands for cash and to generate small timber. Live hedges were common as an agroforestry 9

10 practice in which mehndi, Agave sisalana and Euphorbia species were common. In paddygrowing areas Pongamia glabra and Sesbania grandiflora were grown, lopped annually and their leaves applied to fields as green manure. Application of green manure to paddy field was common in Madhya Pradesh and Uttar Pradesh. In Western Ghats Terminalia leaves were harvested, spread on land, burnt and then paddy, ragi and millets were sown Multistorey homesteads or home-gardens were in existence in Kerala, Karnataka, Tamil Nadu, Tripura, Assam and other North Eastern states as an important agroforestry practice. This practice is still followed in these states. Scope of Agroforestry Agroforestry applies to private agricultural and forest lands and communities. These are highly disturbed, human-dominated land-use systems. Targets include highly-erodible, flood-prone, economically marginal and environmentally sensitive lands. The typical situation is agricultural, where trees are added to create desired benefits. Our goal is to restore essential processes needed for ecosystem health and sustainability, rather than to restore natural ecosystems. Agroforestry provides strong incentives for adoption of conservation practices and alternative land uses, and supports a collaborative watershed analysis approach to management of landscapes containing mixed ownerships, vegetation types and land uses. Fig.4: Bamboo plantation under agroforestry system Possible impacts of Agroforestry Controlling poverty through increased income by higher production of agroforestry products for home consumption and market. Food security by restoring farm soil fertility for food crops and production of fruits, vegetables, nuts and edible oils. Empowerment to women farmers and other less-advantaged rural residents whose rights to land are insecure through better negotiations. Reducing deforestation and pressure on forest by providing fuelwood grown on farms. Increasing buffering capacity of farmers against the effects of global climate change onfarm tree crops and tree cover. Improving soil health of the farm through ameliorated micro-climate and nutrition level. Augmenting accessibility to medicinal trees for cure of common and complex diseases. Features of Agroforestry Agroforestry practices are intentional systematic combinations of trees with crops and/or livestock that involve intensive management of the interactions between the components as an integrated agro ecosystem. These key features are the essence of agroforestry and are what distinguish it from other farming or forestry practices. To be called agroforestry, a land-use practice must satisfy following criteria: 10

11 Fig.5: Intentional: Combinations of trees, crops and/or animals are intentionally designed and managed as a whole unit, rather than as individual elements that may occur in close proximity but are controlled separately. Intensive: Agroforestry practices are intensively managed to maintain their productive and protective functions; these practices often involve annual operations such as cultivation and fertilization. Interactive: Agroforestry management seeks to actively manipulate the biological and physical interactions between the tree, crop and animal components. The goal is to enhance the production of more than one harvestable component at a time, while also providing conservation benefits such as non-point source water pollution control or wildlife habitat. Integrated: The tree, crop and/or animal components are structurally and functionally combined into a single, integrated management unit. Integration may be horizontal or vertical, and above or below ground. Such integration utilizes more of the productive capacity of the land and helps balance economic production with resource conservation. Significance of Agroforestry Agroforestry provides a different land use option, compared with traditional arable and forestry systems. It makes use of the complimentarily relationship between trees and crops, so that the available resources can be effectively utilized. It is a practice that supports the environment and has an obvious landscape benefit. Efficient, modern versions of agroforestry have been developed, that are adapted to the constraints imposed by mechanization. The agroforestry plot remains productive for the farmer and generates continuous revenue, which is not feasible in arable land. Agroforestry allows for the diversification of farm activities and makes better use of environmental resources. Owing to increase in population of human and cattle, there is increasing demand of food as well as fodder, particularly in developing countries like India. Each year farmers of the world must now attempt to feed 81 million more people irrespective of weather. It is important to note that there will be 19% decline in cropland per head by the end of this century due to population explosion. Therefore, there is slight scope to increase food production by increasing the area under cultivation. A management system therefore, needs to be devised that is capable of producing food from marginal agricultural land and is also capable of maintaining and improving quality of producing environment. Agroforestry has interesting advantages from three different perspectives. From the agriculture perspective: 1. Diversification of the activities of arable farmers, with the building-up of an inheritance of multi-purpose trees, with continuous revenue from farm. 11

12 2. Protection of intercrops and animals by the trees, which have a windbreak effect, providing shelter from the sun, rain, wind, soil erosion and stimulating soil microfauna and microflora. 3. Recycling of some of the leached or drained nutrients by the deep roots of the trees; enrichment of the soil organic matter by tree litter and by the residue of the trees. 4. Possibility of combining the interest of the farmer (for an inheritance of wood) and the farm (for access to cultivated land). Possible increased remuneration for the arable farmer for the trees. 5. An alternative to full reforestation of arable land, permitting the continuation of arable activity on land whose arable potential otherwise is conserved. The tree component can be reversed, the plot stays "clean" (free from scrub) and is easy to destump when the trees are clear felled (the stumps are in lines and few in number). 6. In silvipastoral plots, fodder units can be available at different periods compared to full cropped plots, extending the grazing calender. From the forestry perspective: 1. Enhancement in the biomass growth of the trees by wide spacing (+80% over 6 years in the majority of the experimental plantations). A large reduction in the maintenance costs of the plantation, due to the presence of the intercrops. 2. Improvement in the quality of wood produced (wide regular rings, suited to the needs of industry), because the trees are not subjected to cycles of competition and thinning. 3. Guaranteed follow-up and tree care due to the arable intercropping activity. In Fig.6: Wheat in a poplar agroforestry plot particular, protection against the risk of fire in susceptible areas, with pasture or with intercrops like vine or winter cereals (clear bare ground in summer after stubble ploughing). 4. Agroforestry plantations on arable land allow the development of a quality wood resource that complements, rather then competes with, the products from traditionally exploited forests. It is especially important to produce wood that can substitute for tropical saw logs, which will soon decline in availability and quality. The areas concerned will remain small in terms of their absolute value, but the production of wood from them could become a critical input to the European wood supply network. Tree species that are little used in forestry, but are of high value, could be grown in agroforestry systems: service trees, pear trees, common sorbs, walnut trees, wild cherry trees, maple trees, tulip trees, paulownias, etc 12

13 From the environmental perspective: 1. Improvement to the development of natural resources: the total wood and arable production from an agroforestry plot is greater than the separate production obtained by an arable-forest separate cropping pattern on the same area of land. This effect results from the stimulation of complementarity between trees and crops on agroforestry plots. Thus, weeds, which are spontaneously present in young forestry plantations, are replaced by harvested crops or pasture; maintenance is less costly and environmental resources are better used. Fig.7:Mustard intercropped with Kachnar 2. Better control of cultivated areas of land: by substituting for arable plots, the agroforestry plots contribute to diminishing the cultivated area of land. The intensification of environmental resource use by agroforestry systems is not resulting in more crop products. 3. Creation of original landscapes that are attractive, open and favor recreational activities. Agroforestry plots have a truly innovative landscaping potential, and would improve the public image of farmers to society. This will be particularly the case in very sparsely wooded areas, where plots are developed by planting arable land, and in very heavily wooded areas, where plots are developed by thinning the existing forest. 4. Counteract the greenhouse effect: constitution of an effective system for carbon sequestration, by combining the maintenance of the stock of organic material in the soil (the case especially with meadows), and the superimposition of a net fixing wooded layer. 5. Protection of soil and water, in particular in sensitive areas. 6. Improvement of biodiversity, especially by the abundance of "edge effects". This in particular, permits a synergistic improvement, by favoring the habitat of game. The integrated protection of crops by their association with trees, chosen to stimulate the hyperparasite (parasites of parasites) population of crops, is a promising way forwards. 7. These favorable characteristics are as coherent with the many objectives of the laws guiding agriculture and forestry, as they are with the directing principles of the Common Agricultural Policy. Fig.8:Young walnut trees in lavanda plot 13

14 Benefits from Agroforestry Environment Benefits: Combining trees with food crops on cropland farms yield certain important environment benefits, both general ecological benefits and specific on-site benefits. The general ecological benefits include: (i) Reduction of pressure on forest. (ii) More efficient recycling of nutrients by deep-rooted trees on the site. (iii) Better protection of ecological systems. (iv) Reduction of surface run-off, nutrient leaching and soil erosion through impending effect of tree roots and stems of these processes. (v) Improvement of microclimate, such as lowering of soil surface temperature and reduction of evaporation of soil moisture through a combination of mulching and shading. (vi) Increment in soil nutrients through addition and decomposition of litter-fall. (vii) Improvement of soil structure through the constant addition of organic matter from decomposed litter. Economic Benefits: Agroforestry systems on croplands/farmlands bring significant economic benefits to the farmer, the community, the region or the nation. Such benefits may include: (i) Increment in an maintenance of outputs of food, fuelwood, fodder, fertilizer and timber; (ii) Reduction in incidence of total crop failure, common to single-cropping or monoculture system; and (iii) Increase in levels of farm incomes due to improved and sustained productivity. Social Benefits: Besides the economics benefits, social benefits occur from increase in crop and tree product yields and in the sustainability of these products. These benefits include: (i) improvement in rural living standards from sustained employment and higher incomes; (ii) improvement in nutrition and health due to increased quality and diversity of food outputs; and (iii) stabilization and improvement of upland communities through elimination of the need to shift sites of farm activities. Classification of Agroforestry System According to. Nair (1987) agroforestry systems can be classified according to the following sets of criteria: 1. Structural basis: Considering the composition of the components, including spatial admixture of the woody component, vertical stratification of the component mix arid temporal arrangement of the different components. 2. Functional basis: This is based on the major function or role of the different components of the system, mainly of the woody components (these can be product, e.g., production of food, fodder, fuelwood and so on or protective, e.g., windbreak, shelter-belts, soil conservation and so on). 3. Socioeconomic basis: Considers the level of inputs of management (low input, high input) or intensity or scale of management and commercial goals (subsistence, commercial, intermediate). 14

15 4. Ecological basis: Takes into account the environmental conditions on the assumption that certain types of systems can be more appropriate for certain ecological conditions. There may be a set of AF systems for arid and semi-arid lands etc. These broad bases of classification of AF systems are by no means independent. It Is obvious that they have to be interrelated because the structural and functional bases relate to the woody components in the system whereas the socioeconomic and ecological stratification refer to the organization of the systems according to the socioeconomic and ecological conditions. I. Classification of Agroforestry System on Structural Basis: The structural of a system can be defined in terms of its components and the expected role or function of each. In this system the type of component and their arrangement are important. Hence, on the basis of structure, AF systems can be grouped into two categories: A. nature of components and B. arrangement of components. A. Nature of Components: Based on the nature of components, AF systems can be classified into the following categories; 1. Agrisilvicultural systems 2. Silvopastoral systems 3. Agrosilv opastoral systems and 4. Other systems. 1. Agrisilvicultural System (crops and trees including shrubs/vines and trees) This system involves the conscious and deliberate use of land for the concurrent production of agricultural crops including tree crops and forest crops. Based on the nature of the components this system can be grouped into various forms. (i) Improved fallow species in shifting cultivation (ii) The Taungya system (iii) Multispecies tree gardens (iv) (v) Alley cropping (Hedgerow intercropping) Multipurpose trees and shrubs on farmlands (vi) Crop combinations with plantation crops (vii) Agroforestry fuelwood production (viii) Shelter-belts (ix) Wind-breaks (x) Soil conservation hedges etc. (xi) Riparian Buffer (i)improved fallow species in Shifting Cultivation: Fallows are crop land left without crops for periods ranging from one season to several years. The objective of improved fallow species in shifting cultivation is to recover depleted soil nutrients. Once the soil has recovered, crops are reintroduced for one or more seasons. Shifting cultivation, as the term implies, is pattern of land use and a system of production of crops under which plots of land are cleared using a dao or axe which the land is allowed to rest longer than the period of cultivation. However, during the period of rest the land reverts to some modified form of its original cover. It is a system of production almost without capital inputs, requiring primarily manual labour. This system is 15

16 practiced extensively in the north-eastern hill region comprising the states of Assam, Meghalaya, Manipur, Nagaland and Tripura and the Union territories of Arunchal Pradesh, Orissa and Karnataka states. It is called jhum in the north-eastern hill region and podu in AP and Orissa states and considered most destructive for forest areas. The main feature of the improved fallow system of agroforestry is that trees and shrubs are not grown with crops on the same plot at the same time. The fallow periods vary from region to region but are presently becoming shorter due to an increasingly acute land shortage. The best species for the fallow system should induce good nitrogen fixation in the soil. Species: while the main function of the fallow is to maintain or restore soil fertility and reduce, erosion, some plants can be introduced primarily for their economic value. Species choice should not be exclusively confirmed to soil improvers ; plants with marketable products should be compatible with future crops, free of any negative physical or chemical effects on the soil and not in competition with the crop to be planted later on the same site. Establishment: improved fallows can be establishment in a variety of ways and at various stages of the fallow. Methods might include: Direct seedlings of clean tilled, harvested plots; Selective cutting of brush, followed by enrichment planting with tall seedlings. Introducing tall seedlings and cuttings into poor-quality fallows on degraded land; Planting tree seedlings in closely spaced, deep planting holes or furrows within blocks of cleared cropland. The exact techniques vary with the previous land use, value of the fallow vegetation condition of the land and expected duration of the fallow. (ii). Taungya: This is a modified form of shifting cultivation in which the labour is permitted to raise crops in an area but only side by side with the forest species planted by it. This labour is responsible for the upkeep of a plantation. The practice consists of land preparation, tree planting, growing agricultural crops for 1-3 years, until shade becomes too dense, and then moving on to repeat the cycle in a different area. In some cases crops may be grown one year before the trees are planted. A large variety of crops and trees, depending on the soil and climatic conditions, are grown in India (Table 2). The owner of the land and hence the trees is the state Forest Department. In fact this system was introduced to raise forest plantation but finally a recognized AF system (iii) Multipurpose tree species garden: In this system of agroforestry, various kinds of tree species are grown mixed. The major function of this system is production of food, fodder and wood products for home consumption and sale for cash. Major woody species involved in this system are: Acacia catechu, Areca catechu, Phoenix dactilifera, Artocarpus spp., Cocos nucifera, Mangifera indica, Syzygium aromaticum etc. (iv) Alley Cropping (Hedgerow Intercropping): Alley cropping, which is typically regarded as the inter-cropping of trees and crops simultaneously, are mostly characterized by systems which inter-crop valuable nut and hardwood trees with cash crops using widely spaced rows between trees for planting crops. 16

17 Table 2: Tree species and Crops grown in taungya system in India State Tree crop Associated agricultural crops Utter Pradesh (UP) Shorea robusta Maize, paddy, sorghum, pigeon-pea, Tectona grandis so yabean, wheat, barley, chick-pea, Acacia catechu rape-seed and miscellaneous Dalbergia sissoo Eucalyptus spp. Populus spp. Andhra Pradesh (AP) Anacardium occidentale (Cashew) Hill paddy, groundnut, sweet potato Tectona grandis Bombax ceiba, Bamboo Eucalyptus spp. Kerala Tectona grandis Bombax ceiba Eucalyptus spp. Paddy, tapioca, ginger, turmeric Assam Shorea robusta Paddy Tamil Nadu Tectona grandis, Bamboo Millet, pulses, groundnut, cotton Santalum album Tamarindus indica Acacia nilotica Acacia mearnsii Ceiba pentandra Cashew, Rubber West Bengal (WB) Tectona grandis Paddy, maize, millets, turmeric, Shorea robusta Schima wallichii ginger, lady s, finger, pineapple, sunhemp Cryptomeria japonica Quercus spp. Michelia doltsopa Maharashtra Sunhemp, jute, mesta, sunflower, Andaman and Islands Nicobar Pterocarpus dalbergioides castor etc. Sugar-cane, maize The wide alleys more commonly encountered and promoted seem to accommodate most of the typical mid-western crops light requirements and also allow sufficient room for mechanized cropping. Furthermore, the deep roots of trees appear to minimize below-ground competition with crops, enabling these systems to be agro-ecologically sound and economically viable. Economic assessments of alley cropping systems that incorporate for production have shown to have internal rates of return between 4 and 11%. Moreover, they also have economic potential of viably producing timber. Compared to conventional mono-cropping systems, alley cropping systems may prove to be more sustainable and profitable. The alley cropping systems described above differ considerably from the widely promoted alley cropping systems in the tropics and semiarid regions, consisting of closer spaced tree rows typically planted with fast growing multipurpose trees which are often nitrogen fixing and provide secondary products such as fodder, fuelwood or mulch. Carl Much of the current research on these tropical alley cropping systems in the United States also shows some promise 17

18 in their effectiveness of improving soil fertility and overall crop productivity. However, more research on crop tree interactions, management, production and economic aspects of these alley cropping systems needs to be conducted. Alley cropping practices appear to be a rational alternative land use for improving agricultural sustainability while at the same time being economically viable. Nevertheless, there are abundant tree-crop combinations that have not been examined yet as well as a substantial amount of research needed to fully assess their agroecological sustainability, economic potentials, and adoption by farmers and landowners. Fig.9. Illustration of an alley cropping system (Source: USDA, 1996). (v) Multi-purpose Trees and Shrubs on Farmlands: In this system various multipurpose tree species are scattered haphazardly or according to some systematic patterns on bunds, terraces or plot/field boundaries. The major components of this system are multipurpose trees and other fruit trees and common agricultural crops. The primary role of this system is production of various tree products and the protective function is fencing, social values and plot demarcation. Examples of multipurpose trees employed in agroforestry are: Leucaena leucocephala, Acacia albida, Cassia siamea, Casuarina equisetifolia, Azadirachta indica, Acacia senegal, Cocos nucifera etc. (vi) Crop Combinations with Plantation Crops: Perennial trees and shrub crops, such as coffee, tea, coconut and cocoa, are combined into intercropping systems in numerous ways. (vi)crop Combinations with Plantation Crops: Perennial trees and shrub crops, such as coffee, tea, coconut and cocoa, are combined into intercropping systems in numerous ways, including: (a) Integrated multi storey (mixed dense) mixture of plantation crops; (b) Mixture of plantation crops in alternate or other regular arrangement; (c) Shade trees for plantation crops, shade trees scattered; and (d) Intercropping with agricultural crops. (vii)agroforestry Fuelwood Production: In this system, various multipurpose fuelwood/ firewood species are interplanted on or around agricultural lands. The primary productive role of 18

19 this system is to produce firewood: the protective role is to act as fencing, shelter-belts and boundary demarcation. Tree species commonly used as fuelwood are: Acacia nilotica, Albizia lebbek, Cassia siamea, qasuarina equisetifolia, Dalbergia sissoo, Prosopis juliflora, Eucalyptus tereticornis etc. (viii)shelter-belt: Shelter belts are belts/blocks consisting of several rows of trees established at right angles to the prevailing wind. The purposes are: to deflect air currents, to reduce the velocity of prevailing winds, to provide general protection to the leeward areas against the effects of wind erosion, to protect the leeward areas from the desiccating effects of hot wind, to provide food, fodder, timber etc. The fol lowing are the main characteristics of shelter-belts: Shape and composition: Shelter-belts have a typical triangular shape. This can usually be brought about by raising tall trees in the centre. Density and width: A certain degree of penetration by winds is planned as by raising a solid wall, the protection decreases very fast on the leeward side. Shelter-belts up to 50 m' width are considered ideal under Indian conditions. Height and spacing: The ratio of height and width should be roughly 1: 10. However, this figure may vary with local conditions. Orientation: Orientation of shelter-belts depends on the direction and velocity of the prevailing winds. Shelter-belts may be raised in quadrangles if the wind direction tends to change very often. Length: Length is an important consideration in-so-far as shelter-belts are concerned. The minimum length of a shelter-belt should be about 25 times its height. Choice of species: The following species are recommended: Grasses: Saccharum spontaneum, S. munja, Panicum antidotale, Cenchrus sp. Shrubs: Calotropis procera, Clerodendron phlomoides, Cassia auri-cufata, Dodonaia viscosa, Capparis aphylla, Lonnea coromandefica, Tamarix articulata, Parkinsonia acufeata. (ix) Wind-break: Windbreaks have been a traditional agroforestry practice for over 100 years. Windbreaks or shelterbelts are characterized as linear plantings of trees and/or shrubs established primarily for environmental purposes such as reducing wind speed, snow accumulation, retaining soil moisture and buffering extreme temperatures. Integrated as part of crop or livestock production systems, the effects of windbreaks serve to enhance crop and animal production by protecting livestock and crops from harsh environmental conditions in addition to reducing soil erosion from agricultural fields. The height of a windbreak is directly related to the amount of leeward area protected by wind damage. These areas usually extend up to 10 to 15 times the tree height or up to 150 m with 10 m high trees. Some windbreaks system has shown to increase wheat yields by 15% and improve net economic benefits by 17%. Windbreaks may also serve additional benefits such as pollination 19

20 sources for crops, wildlife habitat, and production of timber, posts firewood and other valuable resources. However, very little if any information is available on the economic impacts from these additional products from windbreaks. A variety of potential tree and shrub species can be used to establish windbreaks. However, it is argued that a combination of tall, medium and low growing trees with dense foliage should have the best effect of producing an effective windbreak with suitable porosity. Celtis occidentalis, can also be effective windbreak species due to their fast growth. Wind-breaks are strips of trees and/or shrubs planted / to protect fields, homes, canals or other areas from wind and blowing soil or \ sand. The important reasons for which wind-breaks are planted include: to protect livestock from co ld winds, Fig. 10: Wind-breaks to protect crops and pastures from hot, drying winds, to reduce/prevent soil erosion, to provide habitat for wildlife, to reduce evaporation from farmlands, to improve the microclimate for growing crops and to shelter people and livestock, to retard grass fires, for fencing and boundary demarcation. Wh en properly designed and maintained, wind-breakwater evaporation from soil and plants and can be used to reduce evaporation from water reduce the speed of the wind and thus its ability to carry and deposit soil and sand: They also improve growing conditions by decreasing surfaces such as Irrigation ponds, canals or streams. In addition, wind-breaks can provide a wide range of useful products, from poles and fuelwood to fruit, fodder, fiber and mulch. a. Permeability: A wind-break works by filtering and breaking the force of the wind. For most purposes, permeable wind-breaks which allow some wind to pass through are the most suitable. The slight movement of air through the wind-breaks forms a cushion of slow-moving air on both the upwind and downwind sides. This deflects the main volume of wind upwards and prevents It from descending for some distance. Thus, the wind velocity in the protected area may be reduced to between 25 and 75 per cent of the open wind speed. Dense wind-breaks produce a small area of still air in a narrow strip behind the trees, but further downwind there may be considerable turbulence. However, dense wind-breaks may be desirable when a high level of protection is needed for small areas such as around homesteads and work areas or for vulnerable livestock such as newborn lambs, calves etc. The desired permeability can be obtained by carefully selecting tree and shrub species. Species such as Eucalyptus and Casuarina will form dense wind-breaks but most native species are more 20

21 permeable. b. Orientation: For best results, plant wind-breaks at right angles to the winds from which protection is needed. Wind-breaks planted north-south are a good compromise as they provide protection from winds coming from the western quarter. They also give better shading of adjacent crops and pastures than wind-breaks planted east-west. c. Height: The wind-break height determines the size of the sheltered area. The taller the windbreak, the greater the area it protects. (X) Soil Conservation Hedges: Trees can be planted on physical soil conservation works (grass strips, bunds. risers and terraces), wherein they play two roles: to stabilize the structure and to make productive use of the land they occupy. Stabilization is through the root system. In some of steepy sloping landscapes of the country, the risers or terraces are densely planted with trees, with multiple use being made of them for fruit, fodder and fuelwood. In this system the major groups of components are: multipurpose and/or fruit trees and common agricultural species. The primary role of multipurpose/fruit trees and agricultural species is soil conservation and provision of various tree products. The following tree species are used for soil conservation: Grevillea robusta, Acacia catechu, Pinus roxburghii, Acacia modesta, Prosopis juliflora, Alnus nepalensis, Leucaena leucocephala etc. Trees may also be mixed with staple food crops to produce fruit, fodder or wood. Fruit trees are usually planted along the edges of terraces, e.g., ber (Zyziphus) papaya, dwarf mango, guava, citrus etc. (xi) Riparian buffer: Riparian buffer systems show much promise in rectifying some of the most adverse problems and environmental impacts facing present-day agriculture. Sustainability and environmental concerns relate to the loss of soil, nutrients, and organic matter from agricultural systems and the pollution of agrochemicals and nutrients into waterways by means of runoff. Hence, riparian buffers entail the establishment and management of vegetation (e.g. trees, shrubs and grasses) along denuded waterways to buffer system losses and reduce agrochemical pollution. In contrast to other agroforestry practices, riparian buffer systems have not been traditionally common and their design, research and promotion has been recent. Fig. 11: Illustration of riparian buffer strip (Source: USDA, 1996) An assortment of trees, shrubs and grasses has been suggested for use in riparian buffer strips. These species obviously must be tolerant to flooding or very wet conditions. Moreover, they 21

22 should have a well developed and shallow root system for efficient uptake of nutrients and agrochemicals. Some of the tree species utilized and other buffer systems include willows (Salix spp.), poplars (Populus sppl.), Morus alba and Acer spp. 2. Silvopastoral System (trees + pasture and/or animals) Silvopastoral systems are definitely the most prominent agroforestry practice. Silvopastoral systems are characterized by integrating trees with forage and livestock production. Traditionally, silvopastoral systems involved grazing livestock in wooded rangeland and incorporating trees in pastures for shade and timber. The majority of rangeland grazing in hills is typically comprise the grazing of natural herbaceous and shrubby vegetation for under trees such as pines, bhimal, Oak etc. Research on silvopastoral systems of pine and coastal Bermuda grass have determined their potential of being a better economic investment of land use than producing solely timber or grazing livestock in open pasture. Moreover, if the harvesting of pine straw from the system is included, the economic benefits can exceed even that of the timber. For the most part, studies on silvopastoral systems have shown that growth of trees is not negatively affected when intercropped with forage grasses, although some observations have been made that uncontrolled or excessive grazing can reduce tree survivability and growth of all agroforestry practices being promoted, silvopastoral systems perhaps are the most promising in terms of acceptance and potential economic Fig.12: Illustration of silvopastoral system benefits. Still, there is further research needed on ecological, economic and social aspects of silvopastoral. The production of woody plants-combined with pasture is referred to as a silvopastoral system. The trees and shrubs may b~ used primarily to produce fodder for livestock or they may be grown for timber, fuelwood, and fruit or to improve the soil. A silvopastoral system is needed in dry areas, in particular to help meet wood and fodder demands throughout the year. This system is again classified into three categories: (i) Protein bank, (ii) Living fence of fodder trees and hedges, (iii) Trees and shrubs on pasture. (i)protein Bank: In this silvopastoral system of agroforestry, various multipurpose trees (protein-rich trees) are planted on or around farmlands and rangelands for cut-and-carry fodder production to meet the feed requirements of livestock during the fodder-deficit period in winter. The following protein bank multipurpose trees are planted on or around farmlands. For humid and sub-humid areas: Artocarpus spp., Anogelssus lattifolia, Bombax malabaricum, Cordia dichtotoma, Dalbergia jambolana, Samanea spp., Zizyphus etc. 22

23 For dry regions: Acacia nilotica, Ailanthus excelsa, Opuntia ficus, Prosopis spp., Rhus etc. (ii)living Fence of Fodder Trees and Hedges: In this system various fodder trees and hedges are planted as live fences to protect the property from stray animals or other biotic influences. The following trees are generally used: Sesbania grandiflora, Gliricidia sepium, Erythrina abyssinica, Euphorbia spp., Acacia spp. Etc. (iii)trees and Shrubs on Pastures: In this system various tree and shrub species are scattered irregularly or arranged according to some systematic pattern, especially to supplement forage production. The following tree and shrub species are used: For humid and subhumid regions: Derris indica, Emb/ica officinalis, Psidium guajava, Tamarindus indica. For dry regions: Acacia spp., Prosopis spp. and Tamarindus indica. 3. Agrosilvopastoral System, (trees + crops + pasture/animals) This system has been grouped into two subgroups: (i) Home Gardens: This is one of the oldest agroforestry practices, found extensively in high rainfall areas in tropical south and south-east Asia. This practice finds expression in the states of Kerala and Tamil Nadu with humid tropical climates and where coconut is the main crop. Many species of trees, bushes, vegetables and other herbaceous plants are grown in dense and apparently random arrangements, although some rational control over choice plants and their spatial and temporal arrangement may be exercised. Most home gardens also support a variety of animals (cow, buffalo, bullock, goat, sheep) and birds (chicken, duck). In some places pigs are also raised. Fodder and legumes are widely grown to meet the daily fodder requirements of cattle. The waste materials from crops and homes are used as fodder/feed for animals/birds and barn wastes are used as manure for crops. {fn India, every homestead has around ~ ha land for personal production, on which are grown trees for construction timber, fruits, vegetables, small plots of sugar-cane In more open patches and a surrounding productive live fence of bamboo. Hence one may conclude from the foregoing that 'home gardens represent land-use systems Involving deliberate management of multipurpose trees and shrubs in integrate association with annual and perennial agricultural crops and, Invariably, livestock, within the compounds of individual houses, the whole crop tree-animal unit being intensively managed by family labour'. (ii) Woody Hedgerows: In this system various woody hedges especially fast-growing and coppicing fodder shrubs and trees, are planted for the purpose of browse, mulch, green manure, soil conservation etc. The main aim of this system is production of food/fodder/fuelwood and soil conservation. 4. Other Systems The following systems can be included: (i)apiculture with Trees: In this system various honey (nectar) producing tree species frequently visited by honeybees are planted on the boundary, mixed with an agricultural crop. The main purpose of this system is the production of honey. (ii)aquaforestry: In this system various trees and shrubs preferred by fish are planted on the boundary and around fish-ponds. Tree leaves are used as forage for fish. The main or primary 23

24 role of this system is fish production and bund stabilization around fish-ponds. (iii) Multipurpose Wood Lots: In this system special location-specific MPTS are grown mixed or separately planted for various purposes such as wood, fodder, soil protection, soil reclamation etc. B. Arrangement of Components: The arrangement of components gives first priority to the plants even in AF systems involving animals. Their management according to a definite plan, say a rotational grazing scheme, gives precedence to the plants over the animals. Such plant arrangements in multispecies combinations involve the dimensions of space and time. (i) Spatial Arrangement Spatial arrangements of plants in an AF mixture may result in dense mixed stands (as in homegardens) or in sparse mix stands (as in most systems of trees in pastures). The species (or species mixtures) may be laid out in zones or strips of varying widths. There may be several forms of such zones, varying from microzonal arrangements (such as alternate rows) to macrozonal ones. A common example of the zonal pattern is hedgerow intercropping (alley cropping). An extreme form of zonal planting is the boundary planting of trees on edges of plots and fields for a variety of purposes (fruit, fodder, fuelwood, fencing and protection, soil conservation wind-break and so on). It is also important to note that extreme forms of macrozonal arrangements can lead to sole-cropping systems but the Interactive association of different components can be used as the criterion to decide the limits between zonal AF and sole crop (component) plots. (ii) Temporal Arrangement Temporal arrangements of plants in AF may also take various forms. An extreme example is the conventional shifting cultivation cycles involving 2-4 years of cropping and more than 15 years of fallow cycle, when a selected woody species or mixtures of species may be planted. Similarly, some silvopastoral systems may involve grass leys in rotation with some species of grass remaining on the land for several years. These temporal arrangements of components in AF are termed coincident, concomitant, overlapping (relay cropping), separate and interpolated. II. Functional Classification of Agroforestry Systems: Two fundamental attributes of all AF systems are productivity and sustainability. This clearly indicates that AF systems have two functions. (a) Productive functions (producing one or more products): The various productive functions of AF systems are: (i) Food, (ii) Fodder, (iii) Fuelwood, (iv) Other woods, (v) Other products. (b) Protective functions (protecting and maintaining production systems): The protective functions of AF systems are: (i) Wind-break, (ii) Shelter-belt, (iii)soil conservation, 24

25 (iv)moisture conservation, (v)soil improvement, (vi)shade (for crop, animal and man) III. Socioeconomic Classification of Agroforestry Systems: Based on such socioeconomic criteria as scale of production and level of technology input and management, agroforestry systems have been grouped into three categories: (a) Commercial, (b) Intermediate and (c) Subsistence systems IV. Ecological Grouping of Agroforestry Systems: Based on the major agroecological zones, agrofo restry sy stems are grouped into the following categories: (i)humid/sub-humid lowlands: This region is characterized by hot humid climate for all or most of the year and evergreen or semi-evergreen vegetation. The lowland humid and subhumid tropics (commonly referred to as the humid tropics) are by far the most important ecological region in terms of the total human population. It supports extent of area and diversity of agroforestry and other land-use systems. Because of climatic conditions that favour rapid growth of a large number of plant species, various types of agroforestry plant associations can be found in areas with a high human population, e.g., various forms of home gardens, Plantation of crops with combinations and multilayer tree gardens, in areas of low population density, trees on rangelands and pastures. (ii) Semi-arid/arid lands: This region is characterized by rainfalls confined to 9-21 days in July- 2-4 wet months, vapour pressure deficit ranging from 9 mb in January to 30 mb in April- Sept., May, solar radiation incidence ( cal/cm2/day), high wind velocity (20 km/hour), high potential evapotranspiration (6 mm/day) and high mean aridity Index ( %). (iii).highlands: Variable rainfall, degraded and shallow lands at high altitude to deep rich soils in valleys and great climatic variations are the features of highlands. This area is a storehouse of great biological diversity. The Himalayan region is an excellent example of this type of area. Agroforestry has long encompassed many well-known land-use systems practices. The areas in these high land tropics with significant AF potential are humid or subhumid; those with dry climates have very low potential. land-use problems In the highlands are similar to those in humid or dry lowlands, depending on climate, with the addition that sloping lands and step terrain make soil erosion a major concern. The main agroforestry systems in tropical highlands are: (I) (ii) (iii) (iv) Production systems involving plantation crops such as coffee and tea in commercial as well as small-holder systems; Use of woody perennials in soil conservation and soil fertility maintenance; Improved fallows; and Silvopastoral combinations. Thus it can be seen that there may be many approaches to AF classification. However, a system 25

26 based on the nature of the components and their major functional characteristics for specific purpose appears more logical, simple and pragmatic purpose oriented approach to classification of AF systems. Again, the choice for a system may be based on many interacting considerations - social, ecological and economical. The right choice for the right situation is necessary. Fig. 13: Illustration of multi-species riparian buffer strip Source: National Agroforestry Center, 2000 Tree-Crop Interactions The definition of agroforestry implies that this land-use system must involve two or more plant species at least one of which must be a woody perennial. When perennial woody and herbaceous components are grown together on the same piece of land their performance would largely depend on their ability to share various growth resources in a given environmental situation. Due to difference in growth pattern and resource requirement of the components in agroforestry situation, interactive relation is obvious, which could be of various kinds. The success of an agroforestry system relies heavily on the exploitation of the component interactions. Component interaction refers to influence of one component of a system on the performance of the other components as well as the system as a whole. In an ideal relationship, production of trees as well as crops or grasses in combination could be comparable to their sole performance. Fig. 14:Bamboo plantation for agroforestry Agroforestry could be even more advantageous if production of associated components increases due to influence of trees. This is possible because trees are capable of improving productivity of soil in many ways. A large number of trees are known to fix nitrogen symbiotically. Substantial improvement in organic matter and nutrient content was noted under Prosopis cineria in arid regions. Thus positive role played by tree component could be beneficial to productivity of crop component grown along with trees. Similarly other species could be lopped to provide more sunlight. 26

27 Forest Farming The use of farm woodlots and forests by farmers for obtaining products such as wood, fuel, building materials, sugar, honey and food has been historical. The more popular forest farming practices that are presently researched and promoted by agroforestry institutions consist in the production of specialty products in wooded areas. These products include ginseng (Panax spp.), maple (Acer spp., mushrooms (e.g. morels and shiitake) and pine straw which have become multi-million dollar business enterprises. In addition, there are economic potentials from forest farming from the production of fence posts from trees, as well as production of walnuts, honey, and fruit. However, like the other agroforestry systems described, there is a need of further research to assess their economic and social benefits. Fig. 15: Illustration of forest farming (Source: National Agroforestry Center, 2000) Limitations of Agroforestry An integrated food-tree farming system, while advantageous, does have certain negative aspects. Environment Aspects: (i) possible competition of trees with food crops for space, sunlight, moisture and nutrients which may reduce food crop yield; (ii) (iii) (iv) damage to food crop during tree harvest operation; potential of trees to serve as hosts to insect pests that are harmful to food crops; and rapid regeneration by prolific trees, which may displace food crops and take over entire fields. Socioeconomic Aspects: (i) Requirement for more labour inputs, which may causes scarcity at times in other farm activities; (ii) (iii) Competition between food and tree crops, which could cause aggregate yields to be lower than those of a single crop; Longer period required for trees to grow to maturity and acquire an economic value; (iv) (v) Resistance by farmers to displace food crops with trees, especially where land is scarce; and The fact that agroforestry is more complex, less well understood and more difficult to apply, compared to single-crop farm. 27

28 Through skillful management practices, any or all of these aspects can be controlled. For example, once it is easy to adopt some or all of the following strategies: (i) Select legume trees that have small or light crowns so that sufficient sunlight will reach the food crop for photosynthesis; (ii) (iii) Select tree species that are deep-rooted so that they will absorb moisture and nutrias from the surface layer of the soil; and Space the trees farther apart to reduce their competitive effects on the food crops. Agroforestry Extension Agroforestry has the potential to significantly improve the livelihoods, economic viability, and agricultural production of small farmers in traditionally marginalized areas. In addition, agroforestry can be used as a tool for changing attitudes towards natural resource management. In order to understand how extension can better accommodate natural resource management through the successful introduction of agroforestry and tree planting, extension agents, both public and private, must strive to understand the socio-economics of agroforestry and of the communities within which they work ( On farm ). While agroforestry has traditionally been successful in humid and semi-humid areas, it is most needed in dry-land areas, which are characterized by acute climactic challenges and extremely low levels of agricultural production ( Agroforestry Systems in India 2004 and On farm ). The limits to the adoption of Poplar Field Stall in the field agroforestry are many, but must be viewed beyond technical and biotic constraints of the dryland agricultural regions; the ability of extension agents to recognize socio-economic characteristics of farmers is essential in learning how to target potential innovators who can then generate change within their communities. More emphasis on the development of participatory programs, more efficient targeting, and intensified focus on the traditional communication channels will increase the adoptability of agroforestry in dryland communities. In turn, an implicit understanding that the attitudes of farmers towards natural resource management are based on agroforestry successes and failures will help extension to increase the environmental reclamation of degraded landscapes, especially those in dry, rain-fed agro-ecosystems. Dry-land agricultural areas in India face specific problems that must be overcome for both improved agricultural production Field visit for agroforestry and environmental conservation. Agroforestry can 28

29 help overcome limited water availability, fuel shortages, degraded soils, and a lack of biodiversity ( Agroforestry Systems in India 2004 and CRIDA). When trees are used that are adapted to water-limited areas, such as Gliricidia, communities can realize both agricultural and environmental benefits (CRIDA). In general agroforestry produces a multitude of benefits, including increased income from selling surplus goods, improved environments and enhanced biodiversity, increased access to education through income generation, shelter from harvesting trees for building materials, improved health when medicinal plants are incorporated, a greater diversity of food sources, and an increase in the energy of an agricultural system because manure can be used for fuel instead of food. Specifically in rain fed agro-ecosystems, like those found in dry-land agricultural areas of southern India, successful agroforestry projects can increase the organic matter in soil, improve the physical properties, increase crop yields, increase the availability of nitrogen in the soil, increase the water-holding capacity of soil, and reduce soil erosion. In addition, there is a reduction in pollution because of a decrease in chemical fertilizers. Most environmentally significant, the biodiversity of an agricultural area is enhanced (CRIDA). Agroforestry s scientific benefits as listed above have been well documented within the humid and semi-humid agricultural regions, and the challenge for extension agents is to successfully spread these benefits in dry-land areas where, traditionally, farmers have been marginalized due to resource limitations (such as soil-fertility and water availability). These benefits are of utmost importance in creating a sustainable agro-ecosystem in dry-land agricultural areas, and they cannot be realized without appropriate extension and education. Most importantly such extension and education must be localized and participatory in nature. In order for training and education to be localized, extension agents must understand the important role of socio-economic factors as well as the technical aspects of agroforestry, and therefore they must begin to focus more on the social and communication constraints of the specific villages and communities within which they work. Indeed the foundation of success is the participation of the people for whom the forestry programme is intended. This participation of local residents will help transform the extension programs from the current top down structure, pioneered in transfer of technology methodology, to bottom up participant defined priorities and goals. In this way, participants are much more responsive to the education and training offered by extension agents. In fact, the potential participatory nature of agroforestry programs in rural communities can be a useful vector for knowledge generation that incorporates local information and global science. Villagers and communities, depending on a number of variables, are continually gathering knowledge from various sources, and extension agents should do less to emphasize the strict dichotomy of global science and indigenous knowledge as it can be harmful to the adoption rates of tree management and agroforestry. Poplar in the field Ultimately, Brodt and others advocate that synergy instead of trade-offs be emphasized when extension agents use a variety of knowledge sources to advocate certain practices. Communities within dry-land regions of India have already developed knowledge concerning tree management; however, these knowledge systems are open, thereby allowing an exchange of information which can be more conducive to innovation than enhancing a closed system through strict juxtaposition of local knowledge with global 29

30 science. By allowing the participants to innovate beyond their previous knowledge capacities, extension agents are facilitating local ownership of knowledge, which enhances the success of programs and promotes long term commitment on the part of the farmer and community. The participatory model of extension and education advocated throughout this paper as well as the emphasis on targeting potential adopters and innovators is underscored by a better understanding of local knowledge dissemination and technology transfer among rural farmers in India s dry land regions. When extension agents invest time in learning how villages and farmers communicate, they also see that participatory programs and targeting initiatives are critical in establishing successful agroforestry farms; the decision to adopt agroforestry was found to be determined by the farmers attitude to agroforestry, which in turn was shaped by information received through farmer-to-farmer and farmer-to-extension contact. The mode of communication was important and, to be effective, needs to be customized for each target group. Successful demonstrations by villagers and other farmers decrease the perceived economic risk of agroforestry. In regions where smallholders predominate [like dry-land areas in India], promoting change within the existing farming system may therefore require substantial diversion of resources in order to develop effective communication systems, skills, and media. It is therefore equally important for extension agents to assume the role of facilitators when first entering communities; they can create or enhance pre-existing village meetings and farmer-tofarmer contact. Extension agents can take advantage of the local social structures to increase the adoptability of agroforestry. In addition for small landholders personal communication with neighbors and extension agents are the two modes of Bambusa balcooa under agroforestry communication and knowledge sharing that are most strongly linked to potential adoption and tree planting. Understanding the communication channels and constraints will enable extension agents to enhance village communication and capacity building of farmers, which will, in turn, help demonstrate the low economic risk of agro forestry as well as the environmental benefits and improvements in agricultural yields. Local knowledge, participation, and better targeting by extension agents are critical in establishing a long term commitment to agroforestry in dry-land regions of India. The importance of successful agroforestry extends beyond satisfying agricultural production and economic goals, it is also critical in establishing an understanding of why natural resource management and environmental conservation are important in the sustained productivity of ecosystems. The future of natural resource management depends on the attitudes of farmers which are distinctly shaped by the information they receive from communication channels guided by extension services. Extension agents in India have established the scientific base and technical background to support agroforestry adoption; however they have yet to master the socio-economic tools to analyze communities and enhance local social structures that enable the adoption of agroforestry and facilitate knowledge exchange and generation, critical components of successful agro-ecosystems. If extension agents can use socio-economic analysis to better understand the local conditions in which they operate, the adoption rates of agroforestry will 30