An e-publication by the World Agroforestry Centre
AGROFORESTRY A DECADE OF DEVELOPMENT 
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An e-publication by the World Agroforestry Centre |
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AGROFORESTRY A DECADE OF DEVELOPMENT |
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section 3 Chapter 8 G.B. Singh Assistant Director-General Introduction India, Pakistan, Bangladesh, Nepal, Bhutan and Sri Lanka constitute the "Indian subcontinent". The subcontinent has a total population of about 1,000 million people and a total land area of 4.13 million sq km. Only 20 percent of the total land area is under forest, ranging from 3.8 percent in Pakistan to about 70 percent in Bhutan. It is estimated that the actual area under vegetal cover may be only half of that reported. Besides the need for increasing food production to feed the increasing population of the subcontinent, the urgency of meeting fuel, fodder and timber requirements and preserving the ecological and environmental balance cannot be understated. Agroforestry has a long tradition in the Indian subcontinent. The socio-religious fabric of the people of the subcontinent is interwoven to a very great extent with raising, caring for and respecting trees. Trees are integrated extensively in the crop- and livestock-production systems of the region according to the agroclimatic and other local conditions. While the multi-tier tree-crop combinations in the homegardens of the humid lowlands meet cash and household requirements, the kherji (Prosopis cineraria) and agricultural-crop combination in the hot arid region meets needs for fodder, small timber and food. The Alnus nepalensis and Amomum subulatum combination in the humid sub-temperate regions of Nepal and Bhutan and Sikkim State of India is an excellent example of a commercial but traditional agroforestry system. Deliberate growing of trees on field bunds, their sporadic distribution in agricultural fields, and the systematic retention of shade trees in tea and coffee plantations are other common examples of prevalent agroforestry practices. Similarly, it is a common practice to utilize the open interspaces in the newly planted orchards and forests for cultivating crops for 2-3 years and to interplant shade tolerant crops such as turmeric and ginger later. In India alone it is estimated that the deficit of fuelwood by the year 1990 will be of the order of 100 million m3 per year, and presently only a third of the fodder that is required to feed the country's livestock population is available. About 44 percent of the geographical area of India is subjected to serious erosion hazards, causing an estimated loss of 5,334 million tonnes of soil annually, 1,572 million tonnes of which find their way into the sea. In order to realize the goal of producing 225 million tonnes of food by the year AD 2000 in India, an estimated 20 million tonnes of plant nutrients would be required, a substantial part of which will have to be contributed by sources other than chemical fertilizers. To cope with some of these challenges and tackle these problems of food and environmental security, the potentials of agroforestry need to be fully exploited. Presently some initiatives are being undertaken by the governments, farmers, non-government organizations and industries in the subcontinent to develop appropriate agroforestry systems and popularize them. Matchbox and paper industries have introduced cultivation of poplar trees in the areas about 30° N. Farmers have taken to planting Eucalyptus, Casuarina and Acacia trees either on field bunds or as block plantations. Cultivation of fruit trees has become popular in marginal lands in the arid regions. However, these efforts are only the beginning. Further sustained effort is required to develop agroforestry systems suitable for each agro-ecological region of the Indian subcontinent.
The monsoon, the seasonal reversal of winds and associated rains, develops most prominently over the Indian subcontinent and adjacent seas. The average annual rainfall of about 100 cm over the Indo-Gangetic plains is high for a region lying mostly in the subtropical high-pressure belt. Contrasts in climate are very striking: Cherrapunji, with the heaviest rainfall in the world, and the Thar Desert, with as little as 8 cm of rain per year, are almost on the same latitude (26° N). Almost every type of climate, from equatorial to alpine, is found in one part or the other of the subcontinent. The alpine climate occurs in the Himalayas within 400 km of the Tropic of Cancer. The northern plains experience higher summer temperatures than other land areas on the same latitude, and while over a large area relative humidity is over 80 percent during the south-west monsoon, the air is very dry at the height of summer in the north-west. India has been classified into eight broad agro-ecological regions. Since the neighbouring countries have almost the same agroclimate as in the adjoining parts of India, an extrapolation of these agro-ecological zones to the countries of the Indian subcontinent gives a practical understanding of the entire subcontinent. These agro-ecological regions are shown in Figure 1, and their major features are described below. 1. Humid western Himalayan region The climate in this region varies from hot and subhumid tropical in the southern low tracts to temperate cold alpine and cold arid in the northern high mountains. Annual precipitation ranges from 8 to 350 cm. Three major groups of soils, namely mountain meadow soils, submontane meadow soils and brown hill soils (Cryosorolls, Crychepts, Hapludalfs, Palehumults) occur. Only about 5-17 per cent area is under cultivation. Orchards provide temperate and subtropical fruits. The region has great potential for further development of horticulture and orchards. Indiscriminate felling, overgrazing, soil erosion and soil acidity are the main liabilities. Rich forest wealth and alpine grasslands most suitable for sheep rearing and fruit gardening are the assets. The vast glaciers, after thawing, provide ample water for irrigation in the plains. Crop and animal husbandry can complement the regional economy and allied industries can provide adequate employment opportunities. 2. Humid Bengal-Assam basin This region represents the Ganga-Brahmaputra alluvial plain of continental alluvium and deltaic deposits. The climate is hot and humid with average annual precipitation varying from 220 to 400 cm. Floods are a common feature from mid-July to October. The predominant soil groups are alluvial, red, brown hill and coastal (Udifluvents, Haplaquents, Hapludalfs, Paledalfs, Palehumults, Udipsamments) with extensive patches of saline and alkali soils in the deltaic tracts. Tropical deciduous forests in the west and humid tropical forests in the south constitute the diversified vegetation. In the Assam valley and the submontane tracts, bamboo and cane forests are common. Sal (Shorea robusta) forest abounds on high lands. In Bengal, about 75 percent of the total area is under cultivation, whereas in the Assam valley, cultivated land is limited because of floods. Rice is the major crop of the region. 3. Humid eastern Himalayan region and Bay islands The eastern Himalayan ranges, with a widely varying elevation, contribute to the rugged physiography of the region. About 90 percent of the total precipitation (200^400 cm) is received during the monsoon. The predominant soil groups are brown hill, red loamy, red and yellow, alluvial and laterite (Hapludalfs, Hapludults, Paleudalfs, Plinthudults and Udifluvents). In the foothills, alluvial soils are loam to sandy loam in texture and slightly acidic to neutral in reaction. The soils contain a fairly high percentage of organic matter. The region is endowed with rich forests. Tropical evergreen forests are found in the foothills and plains, and temperate evergreen forests in the middle Himalayas and valleys. The greater Himalayan ranges are covered by conifers. In the Bay islands, mangrove forest is present along the coast. Bamboo is extensively grown in the tropical evergreen belt. The main feature of the farming system is shifting cultivation practised in the north-eastern hills. Horticulture, animal husbandry and aquaculture have great potential. 4. Subhumid Sutlej-Ganga alluvial plains But for the Terai-Bhabar submontane strip, the entire region is level and built up by the mighty rivers originating in the Himalayas. Extremes of climate prevail in the region. The average annual rainfall varies from 30 to 200 cm in the plains and ground frost is common in December and January. The predominant soil groups are calcareous sierozem in the south-west, reddish chestnut in the submontane zone, alluvial soils and patches of saline alkali soils (Calciorthids, Hapludalfs, Calciorthents, Ustochrepts and Salorthids). Cultivated land is 65-85 percent of the total area. The major part of the region consists of introduced vegetation of sal, teak and bamboo. In Terai soils, tall grasses are found which serve as good raw material for the paper industry. 5. Subhumid to humid eastern and south-eastern uplands The region is characterized by undulating topography, denuded hills, plateaus, mature river valleys, highlands of the Eastern Ghats and wide basins. Elevation ranges from 150 to 1,500 m. The climate is tropical monsoonal and subhumid to humid from west to east. Rainfall ranges from 100 to 180 cm. Predominant soil groups are mixed red and black, red and yellow, red sandy, laterite, black, riverine alluvial and coastal sandy alluvial (Pellusterts, Chromustent Haplustults, Ochragults, Haplustalfs, Hapluquants). Rice is the.predominant crop in the high-rainfall areas, coastal plains and deltaic tracts. In the drylands, sorghum is the major crop. In the eastern part of Madhya Pradesh and Orissa States of India, forests occupy 40-45 percent of the total land. Teak and sal are the dominant plantation species. Soil salinity and floods in the coastal districts are the two major impediments to agricultural production. 6. Arid western plains The region is an extensive alluvial plain dotted with sand dunes, sandy plains, saline depressions and granite hills intersected by the Aravalli range. Annual precipitation is scanty and erratic, ranging from 10 cm in the extreme west to about 65 cm in the extreme east. Most of the rains are contributed by the south-west monsoon during July-September. The deficiency of moisture varies from 40 to 100 percent from east to west. Predominant soil groups are alluvial, grey brown alluvial, black desert, saline and alkaline (lithic Entisols, Calciorthids, Salorthids and Ustochrepts). Frequent dry spells make the region drought prone and incapable of sustaining plant growth. The region is devoid of trees. Scrub and scattered vegetation are further depleted by cutting and browsing. Natural grasslands have been considerably degraded. In the arid regions pearl millet and sorghum are the major crops, whereas in the semi-arid environment and irrigated areas a variety of crops could be grown. 7. Semi-arid lava plateau and central highlands The region is a plateau ranging from 300 to 1,400 m of horizontally bedded sedimentaries and basalt. Between the highlands, there are wide alluvial plains. The climate is semi-arid with extremes of temperature and variable rainfall. The annual precipitation, confined to June-October, varies from 70 to 125 cm except in the Western Ghats where it varies from 335 to 743 cm. The major soil groups of the region are alluvial black and lateritic, mixed red and black and yellowish brown (Paleustalfs, Rhodustalfs, Haplustalps, Chromusterts, Plinthudults, and Haplustults). The dominant forest types include moist and dry deciduous, semi-evergreen and thorny and scrubby vegetation. Semi-evergreen forests are confined to the Western Ghats and the rest of the plateau is covered with deciduous types. Low and uncertain rainfall, undulating topography and inadequate irrigation impede agricultural activities. 8. Humid to semi-arid Western Ghats and Kamataka Plateau The region can be divided into the Western Ghats Plateau, river valleys, undulating rocky plains and coastal plains. Rainfall varies from 60 to 300 cm. Important soil groups are black, red, lateritic and alluvial (Pellusterts, Chromusterts, Ustifluvents). The western slopes of the Eastern Ghats and the Nilgiris have tropical evergreen forests and the eastern slopes and uplands grow deciduous forests with sandalwood, eucalyptus, sal and teak. The cultivated area varies from 10 percent in the Western Ghats to 54 percent in the Karnataka plateau. About 10 percent of the land is irrigated. Dry farming is practised throughout the region. Forest land and plantation areas have the potential for growing fodder trees, legumes and grasses.
Mixed farming systems have been a traditional way of life for the fanners of the Indian subcontinent. In every village there are combinations of tree, crop and animal-husbandry activities according to the local requirements. Some of these combinations have stood the test of time and are practised extensively. The most important of these agroforestry systems are described below.
This sequential agroforestry system, believed to have originated in the Neolithic period around 7000 BC (Sharma, 1976), is still extensively practised in the North Eastern Hill (NEH) Region and some other humid and hilly parts of the Indian subcontinent. FAO (1981) estimates that about 4,500,000 people practise shifting cultivation annually over an area of 750,000 ha in this region. The reasons for its continuance are linked to ecological, socio-economic and cultural factors, including lack of communication because of remoteness. Details of the tenurial system, field operations, crop mixtures and socio-economic considerations involved in the practice have been well documented by Borthakur et al. (1981) and FAO (1981). It has been indicated that due to increasing pressure of population the length of forest fallow has decreased alarmingly from the original 30-40 years to as low as 2-3 years at present. This gradual shrinkage in the cycle of jhuming is the sign of an imminent breakdown of the system because of the very short time that is available for the land to restore its fertility. Studies conducted under humid tropical conditions in India have reported a loss of 40.9 t ha'1 of soil in the first year of jhuming, resulting in a heavy drain of plant nutrients from the jhum plots (FAO, 1981). Since no fertilizer input is given to these fields, the resultant productivity of the crops is low. The gross value of the products from one hectare of jhum was only Rs 505-6551 with a maximum return of Rs 2.48 per man day and an input-output ratio of 1:1.28. Concerned by the continuous degradation of the environment of the tribal families dependent on shifting cultivation, the Government of India, in collaboration with the local state governments, launched a number of initiatives to control the problem. The main approach of these schemes was to provide some terraced and afforested land planted with fruit trees to each family so that the farmers could be attracted towards settled agriculture. However, surveys revealed that the project did not meet with much success. This failure was attributed to:
The approach now being tried is to improve the existing jhum system by providing suitable management packages based on local resources. The abandoned jhum lands are planted with desirable tree species and legumes so that fertility can be restored as quickly as possible. Research and development efforts towards an appropriate alternative fanning system are also in progress. However, the acceptance of these new components in the system depends on provision of an adequate infrastructure for marketing and an assured supply of essential inputs for the jhum farmers.
The taungya system, a method of establishing forest species in temporary combination with field crops, was attempted in the Indian subcontinent soon after its first introduction by Brandis in Burma in 1856. However, regular taungya cultivation was not taken up until 1911 when it was used for raising plantations of Shorea robusta and Tectona grandis in 1912. Later, it became a standard practice for regenerating and/or establishing forest plantations in a number of places (see King, this volume). The system, which is initiated and executed by the Forest Department, allows the cultivators to raise agricultural crops in the reserve forest area allocated for new plantations. Input and care given to the agricultural crops in the interspaces improve the growth of the associated trees. The major forest species raised in taungya cultivation are Shorea robusta and Tectona grandis. A number of other fast-growing tree species were also taken up under this system in order to exploit the advantages of the soil enriching benefits associated with the growing of agricultural crops in the inter-row spaces. The intercrops varied according to the agro-ecological situation. Some of the main crops are rice, millet, maize, gram, mustard, sugarcane, cassava, cotton and potatoes. The system is practised in India and Sri Lanka and the various steps being taken to make it more effective have been described in detail (FAO, 1981). Studies to evaluate changes in fertility of forest soil after the harvest of inter-cultivated crops have registered a definite increase in organic carbon, phosphorus and potassium (FAO, 1981). In poplar plantations, the yield of interplanted rice, make and wheat was 4,000, 3,000 and 3,000 kg per hectare, respectively. The height of Dalbergia sissoo in combination with peanuts increased up to 23 percent compared to control plots in the initial stages (58.8 cm against 47 cm). Intercropping of turmeric (Curcuma longa) in the established plantation of Tectona grandis, Shorea robusta and other common forest species resulted in encouraging responses. A yield of 1,200 kg per hectare of turmeric was obtained when the plantations were two years old. With increasing age of plantations, however, the yield of turmeric decreased. Under the taungya system as followed in Sri Lanka, the emphasis is on reafforestation of land that is abandoned by non-resident cultivators within a period of three years. The main tree species planted are Tectona grandis and Eucalyptus camaldulensis and intercropping of a variety of agricultural crops is done. Prominent among such intercrops are rice, maize, plantain, chilli and mustard. The area under this system in Sri Lanka is decreasing drastically due to the lack of farmers interested in the practice. The high labour requirement is also a major deterrent. Although the taungya system helps the initial establishment and growth of forest species, minimizes the cost of maintenance of the trees, and in some cases earns revenue for the forest department on the one hand and provides employment to the rural poor, the interest of the forest department in this system is decreasing. The difficulty the forest officers have in getting the area vacated is said to be the major deterrent factor. Sometimes the farmers cause damage to the growing trees and adjacent forest areas. However, considering the ecological and socio-economic benefits of the system, there is a strong case for forest departments to pursue the approach further.
Historically, Prosopis cineraria, loyally known as khejri, has played a significant role in the rural economy of the arid north-west region of the Indian subcontinent. This tree is an important constituent of the vegetation system and is a source of animal feed, fuel and timber. Its pods are used as a vegetable. It improves the fertility of the soil beneath it, is well adapted to arid conditions and stands up well to the vagaries of climate and browsing by animals. The rural communities encourage the growth of khejri in their agricultural fields, pastures and village community lands, as depicted in Figure 2. Through experience, farmers have realized its usefulness and learnt that it does not adversely affect crop yields but actually improves grain yield and forage biomass production. However, one of the limitations of khejri is its rather slow growth. Extensive studies carried out by the Central Arid Zone Research Institute (CAZRI) in Jodhpur, India on the growth pattern, influence on associated agricultural crops and biomass/ economic productivity have been summarized in a CAZRI monograph (Mann and Saxena, 1980).
Agroforestry involving the khejri tree is an age-old practice in arid and desertic conditions. The farmers in the region know the value of these trees and ordinarily will not cut them for fuel. The density of khejri trees varies from a few trees to 120 per ha depending on the soil type and rainfall. Alluvial plains with sandy loam soils invariably support more trees. In a well-developed tree stand on alluvial soils all trees are lopped for foliage (loong) in a systematic manner during November and December each year. When winter sowing is to be done early, the lopping is completed by the end of October, particularly when wheat is to be sown. The lopped trees remain dormant up to the middle of February. The plant sprouts well with several new branches which are again cut during May-June for livestock feeding. This management of the crown during dry periods keeps down the amount of foliage in the crown. In June-July (the rainy season) the undersown crops and the canopy cover of the tree develop simultaneously. The crop and tree do not compete with each other. Annual crops draw their moisture and nutrients from the top 50-60 cm of soil, whereas the effective root system of the tree is below this depth. The crops which are normally raised along with the khejri tree are millets, especially Pennisetum glaucum, and a variety of legumes. The khejri tree, though initially slow growing, provides a continuous supply of fodder, fuel, timber and vegetables even in drought years. There is a need for careful selection of comparatively fast-growing khejri germplasm and to supply these seeds to other areas.
A homestead (or homegarden) is an operational farm unit in which a number of tree species are raised along with livestock, poultry and/ or fish mainly for the purpose of satisfying the fanner's basic needs. Such a farming system is traditional to the eastern and southern parts of the Indian subcontinent. Homestead agroforestry practices have been described by Khaleque (1987) from Bangladesh, Nair and Sreedharan (1986) from Kerala, India, and Liyanage et al. (1985) from Sri Lanka. A typical homestead with a multitude of crops presents a multi-tier canopy configuration (Soemarwoto, this volume). The leaf canopies of the components are arranged in such a way that they occupy different vertical layers with the tallest component having foliage tolerant of strong light and high evaporation demand and shorter components having foliage requiring or tolerating shade and high humidity. The major portion of the upper canopy goes to coconut, which is followed by other crops such as black pepper, cacao and tree species. The lower storey of the harvesting plane is occupied by banana and cassava and other tuber crops. At the floor level, pineapple, vegetables and other herbaceous crops are grown. However, wide variation in the intensity of tree cropping is noticeable among homegardens in different places. This is generally attributed to the differences in socio-economic conditions of the household and their response to externally determined changes, particularly prices of inputs and products, dependence on land and tenurial conditions, etc. A schematic representation of the activity of an intensive homegarden, as described by Nair and Sreedharan (1986), is presented in Figure 3. A study conducted by a voluntary organization in the homesteads of Kerala reported a net income of Rs 1,550, 3,848 and 3,950 from a 0.12 ha plot in the first, second and third year, respectively (Nair and Sreedharan, 1986). The components of the system consisted of a three-tier planting of fodder, cassava, vegetables, a number of bananas, cloves and coconut with Leucaena being planted all around. A cow, which formed a part of the scheme, not only provided milk for consumption and sale but also manure. Chemical fertilizers were not used at all. It is evident from this case study that farmers with ingenuity have been able to develop a self-sustaining organic farming system capable of yielding a high income without much input other than the family labour.
However, there is a need to look into the best possible arrangements of different components in the system and also to explore the inputs required to maintain the productivity of the system. The Central Plantation Crops Research Institute, Kasaragod, Kerala, India along with the Kerala Agricultural University, have on-going research on the various management aspects of high-density coconut-based multiple cropping systems.
A less systematic form of tree growing on farm lands is traditionally practised almost everywhere in the Indian subcontinent. The approach and uses for tree planting in unirrigated semi-arid and arid areas are different to those in the irrigated and humid areas.
In these areas the systems have a strong pastoral bias, permitting the combination of animal husbandry with agriculture since free grazing of cattle is rarely allowed. The systems are agrisilvicultural rather than silvopastoral. Prosopis cineraria, Acacia nilotica, Acacia cupressiformis, Pongamia pinnata, and Gliricidia sepium are some of the tree species which are present in farmlands for meeting fodder requirements. The partial shade cast by the trees reduces insolation and soil temperature which is beneficial to the associated field crops. It is a common sight in certain parts of Uttar Pradesh, India to see individual fields surrounded by very closely planted rows of Dalbergia sissoo and Syzygium cuminii which are normally raised on high bunds along the boundaries. Similarly Azadirachta indica, Melia azedarach, and Albizia lebbek have been traditionally planted on the field borders in the semi-arid areas. Under dryland cropping systems, deficiency of soil moisture is the greatest limitation for crop production. Normally, these tree combinations are selected in such a way that the different species do not extract much moisture from the same soil layer.
The prosperity generated by the "Green Revolution" in the irrigated areas of the Indian subcontinent made the general scarcity of wood all the more troublesome and farmers therefore took the progressive step of planting fast-growing trees around their homesteads, along field boundaries and irrigation channels and also within the fields. The preferred tree species are Eucalyptus tereticornis, Poplus spp. and Dalbergia sissoo which cast only light shade (Figure 4). Eucalyptus grows fast to produce a straight cylindrical bole which is in much demand as round and sawn timber and as pulpwood. Lops and tops are used as fuel. Dalbergia sisoo provides high-quality furniture wood, fuel and fodder. This kind of planting, although a traditional practice, has quite recently became a prominent feature of the rural landscape, especially in Punjab, India (see Figure 5). The cash value realized from the sale of trees is very high and more than compensates for any marginal adverse effects that the planting of such trees may have on the crop yields. The trees do not directly compete with the shallow-rooted agricultural crops either for the irrigation water or for fertilizers, nor do the species selected cast enough shade to be detrimental to the crop growth. Trees do attract birds, but perhaps the loss of grain is more than compensated for by the elimination of insect pests (FAO, 1981).
The Indian subcontinent with 995 million people and 540 million livestock is one of the most densely populated regions in the world (240 persons and 130 livestock per sq km; FAO, 1985). Demographic projections for India alone estimate a population of about 1,000 million people by the year AD 2000. To support such a large population the amount of food, fodder, fibre, timber and energy required will be enormous. Fuelwood, which is still the major source of rural non-commercial energy (40-50 per cent) is in great shortage. As against the estimated requirement for India of 133 million tonnes of fuelwood per annum, all the present and projected sources produce only about 39 million tonnes (Government of India, 1982). Similarly, in Pakistan, against a requirement of 18.9 million m3 of fuelwood, state forests produce only 1.9 million m3 (Sheikh, 1987). The situation in Bangladesh, Nepal and Sri Lanka is no better. One of the worst repercussions of fuelwood scarcity is the burning of considerable quantities of cowdung and crop residues which otherwise could be used in restoring soil fertility. The Committee on Fodder and Grasses appointed by the Government of India in 1985 estimated the availability of only 224.08 million tonnes of green fodder against a requirement of 611.99 million tonnes for supporting the present livestock population. Since a decline in soil productivity due to intensive-cropping and improper management of soil is a general feature in the subcontinent, and chemical fertilizers are very expensive, the use of biological alternatives for enriching the soil is one of the major concerns in these countries. Present land-use patterns presented in Table 1 show that only 24.3 percent of the subcontinent is under forest, woodland and permanent pastures. Apart from the forest area being precariously small, it is also extremely degraded and hardly 50 percent of it may be under good vegetal cover. Village woodlands are seriously depleted. Tree planting on unused lands, categorized as "waste lands and barren lands", and in conjunction with agricultural crops on arable land, seems to be the main hope for providing food and environmental and economic security in the subcontinent.
Government-run social forestry schemes have made a good impact in some areas. Recently, some non-governmental organizations (NGOs) have also been active in this area. But the major thrust in integrating trees with agriculture will have to come from the farmers themselves. The motivation may be diversification of production for meeting their own requirements, cash generation, or even the scope for sustainable production in marginal and arid areas compared to the field crops. Some farmers have already taken the initiative in this direction, and to meet the need for an appropriate management strategy for tree-crop integration the national governments have started strengthening the research and development infrastructure. A brief account of some such efforts is given below. India Research work on fuel and fodder production systems by the Central Soil and Water Conservation Research and Training Institute, Dehra Dun; on silvopastoral systems by the Indian Grassland and Fodder Research Institute, Jhansi; on shelterbelts and agrisilviculture systems by the Central Arid Zone Research Institute, Jodhpur; and on a mixed system consisting of agricultural, horticultural and silvicultural components as an alternative to shifting cultivation by the Indian Council of Agricultural Research (ICAR)'s research complex for the North-Eastern Hill region was initiated during the late 1960s and 1970s (Singh and Randhawa, 1983). Even prior to the above initiatives by the ICAR, the Forestry Department of the Government of India had taken up elaborate studies on taungya cultivation. Vishwanathan and Joshie (1980) successfully utilized the bouldery riverbeds in Dehra Dun by raising Dalbergia sissoo and Acacia catechu trees in conjunction with Chrysopogon fulvtis and Eulaliopsis binata grasses. The yield from such a system over a period of 19 years is given in Table 2.
Under similar conditions, Singh et al. (1982) tried four fodder-tree species, namely Albizia lebbek, Grewia optiva, Bauhinia purpurea and Leucaena leucocephala in association with Eulaliopsis binata and Chrysopogon fulvus. The results are given in Figure 6. The Grewia optiva and Eulaliopsis binata system proved to be the most rewarding in terms of total return on such degraded lands under rainfed conditions. While evaluating the effect of trees planted on farm boundaries, Khybri et al. (1983) reported a more pronounced effect of boundary trees on winter wheat than on a rainy-season crop of rice, perhaps due to the limitation of moisture availability during the winter season. Srivastava and Narain (1980) studied the effect of a 20 year-old Eucalyptus tereticornis tree line planted on the farm boundary on crops under rain-fed semi-arid conditions. Serious reductions in crop yields were noticed of up to 10 m in the case of green gram, up to 5 m in black gram and only 2 m in the case of sorghum. At the same site (Kota, India), Prasad and Verma (1983) studied the effect of Leucaena alleys on associated crops of sorghum, sorghum and pigeon pea, and sorghum and black gram. The results, presented in Table 3, indicate some reduction in the yields of pigeon pea and black gram grown in association with Leucaena compared to pure crop, but the additional biomass yield from Leucaena makes the combination more paying. In order to study the interference effect of tree roots on associated agricultural crops, Singh and Dayal (1974) dug a 15 m x 1.0m trench along the field boundary of a 15-year-old plantation of Dalbergia sissoo and Acacia arabica planted on peripheral bunds of cotton and tobacco fields and evaluated the crop yields. In this semi-arid situation elimination of D. sissoo roots from the crop-root zone increased the yield of cotton from 956 kg ha ' to 1,056 kg ha-1; the yield of tobacco increased from 1,206 kg ha-1 to 1,859 kg ha-1 by pruning the roots of the Acacia arabica. However, Dadhwal and Narain (1984) did not find any significant effect from trenching along Eucalyptus rows on maize under high-rainfall conditions. Studies conducted on agroforestry systems in arid regions of India have been described by Shankarnarayan et al. (1987). The introduction of Acacia tortilis, a comparatively fast-growing tree, in the arid zone has helped in the stabilization of sand dunes and early establishment of sheltefbelts. Acacia tortilis with the grass Cenchrus ciliaris in a silvopastoral system earned maximum returns among the different combinations tried.
Lopping of eight-year-old Holoptilia integrifolia caused a favourable effect on the associated crops of mung bean (Vigna mungo) and cluster bean (guar) (Cyamopsis tetragonoloba), as shown in Table 4.
In another experiment, the growth rates of Prosopis cineraria and Acacia albida and their influence on the associated crops of mung bean and guar were studied. Acacia albida was found to grow much faster with a height increment of 110 cm in three years compared to only 15 cm in the case of P. cineraria. The results of this study are presented in Table 5. It is interesting to observe that, in general, the association of trees with crops improved the crop yield in these experiments. During 1985, when the general level of crop yield was very low due to moisture stress, the yield of guar improved due to the association of Prosopis cineraria. In the semi-arid region at Jhansi the performance of Leucaena leucocephala was evaluated in a silvopastoral combination (Gill and Patil, 1983). It was found that the tree was compatible with a number of forage-production systems. Total biomass production in association with Leucaena was invariably higher compared to monocrop systems. Borthakur et al. (1981) suggested a "silvi-agri-horti" system as an alternative to shifting cultivation in the North-Eastern Hill Region of India. The system is more productive than shifting cultivation and other indigenous systems and reduces the risk of soil and water loss to a great extent. Singh and Singh (1987), while summarizing the work on alternative farming systems for the drylands of semi-arid tropics of India, highlighted the effect of the addition of Leucaena loppings to the soil in the improvement of sorghum grain yield (Table 6). It is interesting to note that the addition of biomass from other sites in combination with fertilizer nitrogen increased the yield of sorghum. However, the communication does not indicate the quantity of lopping added in the experiment.
Table 6 Effect of Leucaena leucocephala planting, lopping addition and levels of fertilizer nitrogen on the grain yield of rabi sorghum; Solapur, India
Besides the Institutes of the Indian Council of Agricultural Research (ICAR), certain state agricultural universities have also initiated systematic research work on agrogforestry systems. The pioneers among them are the Tamil Nadu Agricultural University, Coimbatore and the Agricultural University located at Dharwar. On the recommendation of the task force constituted during the Agroforestry Seminar organized at Imphal, India in May 1979, ICAR launched an All India Coordinated Research Project on Agroforestry spread over 20 centres in the country in 1983. The core research activities at these centres are (i) conducting a survey of the existing agroforestry practices, (ii) collection and evaluation of the local agroforestry tree species, and (iii) development of location-specific agroforestry systems. With the increasing interest in agroforestry in the country, the programme of the All India Coordinated Research Project on Agroforestry has since been extended to 11 more centres covering all the 23 state agricultural universities, and it has been decided that a National Research Centre on Agroforestry be established during the seventh five-year plan of India (1985-1990). Pakistan Since the area under forest in Pakistan is very small (3.8 per cent), about 58 percent of timber and 90 percent of fuelwood requirements are being met from farm and wasteland plantations. If integration of trees with agricultural systems is needed anywhere in the world, the plains of Pakistan deserve the highest priority. Tree planting has not been properly organized and still a large majority of the rural community is not fully motivated to plant trees due to the belief that the trees compete with agricultural crops for water, nutrients, light and space and harbour birds which cause damage to the associated crops. However, the introduction of poplar, a multipurpose tree, has changed the rural scene in some areas. There is tremendous demand for poplar wood from the various wood-based industries in Pakistan. It has also been established that Eucalyptus can be successfully grown in marginal lands where average annual rainfall is about 300 mm. Certain studies on the tree/ crop interface were conducted in the country. Sheikh (1987) found that crop yields were affected by growing them in association with Acacia nilotica and Dalbergia sissoo, the maximum loss occurring in a 2-metre radius from the tree. Yields were poorer from the crop planted on the northern side of the tree. Kermani (1980) reported the results of large-scale experiments to find the effect of growing Acacia nilotica and Eucalyptus camaldulensis in association with cotton, wheat, sesamum and sorghum. It was found that the yields of agricultural crops were higher when grown in association with E. camaldulensis. The eucalyptus and cotton combination was the best, giving higher yields of wood as well as better monetary returns from the agricultural crops. Khattak et al. (1980) found that the yield of wheat under Dalbergia sissoo was significantly higher than that of wheat under Eucalyptus citridora, Populus deltoides or Bombax ceiba. Sheikh and Haq (1986) summarized the results of tree/crop interface experiments conducted in the Thai Desert and observed an almost uniform response pattern. Wheat yield was depressed up to 5 metres from the tree rows, but total yield of wheat from a tree-associated plot was higher than that of the control plot. Trees (D. sissoo, Tamarix aphylla and P. deltoides) were not different in their effect on crop yield. The farmer was able to make good the crop loss through the sale of trees at fairly good prices. Sheikh and Haq (1986) recorded a depressing effect of poplar rows on the yield of sugarcane crop up to 10 m away from the trees. The important findings emerging from the different studies conducted in Pakistan, as summarized by Sheikh (1987), are (i) trees in close proximity to agricultural crops depress the yield of the latter, (ii) the effects vary depending upon the species of trees and crops, and (iii) farmers are prepared to plant trees provided the species are fast growing and have a good market value. The information available so far indicates that a great potential exists for agroforestry in the plains of Pakistan. However, development efforts need to be backstopped by necessary research to find solutions to the various problems encountered. Bangladesh The majority of people in Bangladesh obtain their fuel, fodder and timber from homestead forests. According to one estimate, homestead forests produce about 70 percent of sawlogs and about 90 percent of fuelwood and bamboo consumed in Bangladesh (Byron, 1984). A survey on the practice of homestead plantations indicated that farmers prefer fruit trees to other species, and fuelwood is seen as a by-product. However, as suggested by Khaleque (1987), there is a need to work out the homestead planting in such a way that most of the requirements of the household are met. Moreover, the development of a marketing infrastructure would be necessary to make fruit-tree planting profitable. Sri Lanka The country practises a number of agroforestry systems. The most prominent are chena, a form of shifting cultivation, some forms of taungya, intercropping under coconuts, homegardens, growing tea and coffee under the shade of trees and windbreaks/ shelterbelts (Liyanage et al, 1985). Moringa oleifera is commonly planted in hedges around homesteads throughout the dry zone. It is the normal practice to grow cowpea and other crops under the tree since the crown is light and the yields of crops are not decreased by the tree's shade. Sesbania grandiflora, a short-lived tree of medium height, is often grown in and near homesteads for its tender leaves and flowers that can be used as a vegetable. Nepal and Bhutan Growing of multipurpose tree species hi the agricultural fields and around the homestead specifically for fodder and fuel is a common practice. Planting Amomum subulatum (large cardamom) in association with Alnus nepalensis is a major cash-generating agroforestry system in these countries. A comprehensive list of multipurpose tree species found on the farmlands in Nepal is given by Fonzen and Oberholzer (1985). The multipurpose tree species common to Bhutan and Sikkim have been described by Singh and Pazo (1981).
We can conclude that the role of agroforestry in meeting either present or future requirements of fuelwood, food, fodder and small timber and for environmental protection has been very well recognized in the Indian subcontinent. What is now required is the development of location-specific, need-oriented systems along with the necessary support systems so that farmers can get the required seedlings and other inputs easily and market the produce at competitive prices. With a population growth rate of over 2 percent in most of the countries of the subcontinent, the challenge of meeting basic requirements of the population is a major concern. The exploitative tendency of modern agriculture, aimed at higher and higher production per unit area, is in fact rapidly degrading the basic production capacity of the ecosystem. Long-term experiments conducted in India have indicated very clearly that in high-production areas the soil is quickly depleted of essential plant nutrients. In certain regions where ground-water recharge is slow the rapid withdrawal of ground water has alarmingly lowered the watertable. Village woodlands and grazing grounds have vanished, resulting in acute shortages of fuel and fodder. Government-managed forests that are already denuded are heavily exploited for meeting timber requirements. Deforestation and cultivation on steep slopes have resulted in heavy soil losses and water runoff. These things have happened, perhaps, because agricultural research and development efforts have given greater emphasis to individual production sectors or components than to the whole system. Fanners in the subcontinent basically practise a mixed-farming system. Their way of life is an integration of different components for optimum production without necessitating much external input. Agroforestry presents an excellent opportunity for such low-input socio-economic situations as it provides for the integration of various production factors for achieving need-based goals. Whether it is the problem of apple boxes in the hills, or fodder and fuel in the semi-arid/arid areas, or shelterbelts in deserts, or ground cover in high-rainfall areas, or cash crops in high input areas, trees can play a role and can be suitably integrated with the existing agricultural production system. It is for the scientists engaged in agroforestry research to identify trees for a specific role in a particular ecosystem and to synthesize and develop the agroforestry system based on existing components so that the production can be optimized without impairing the quality of the resources. Fortunately, in the Indian subcontinent the information on the component technology is not lacking, whether it is tree, crop, animal, soil, water or environment. In some countries of the subcontinent, work on the development of appropriate agroforestry systems has already started; others are in the process of developing the needed infrastructure. However, considering the urgency of such an approach for application to the field, there is no need to wait for elaborate infrastructural developments. What may be required is to develop multidisciplinary teams which are capable of synthesizing appropriate systems and have the capacity to manage the components for realizing the objectives of the systems. Agroforestry research should have as a high priority the identification of appropriate tree species for their assigned role in the system in a particular environment. A wide range of indigenous and exotic species is available for selection. The ingenuity of the researcher lies in developing a management system which may integrate the selected tree species with on-going land-use activities in such a manner that the overall production gains are higher, without impairing the basic resources. It may be necessary to go for more "on farm" trials so that the synthesized systems can be tested and modified on farmers' fields before they are tried for large-scale extension. A number of systems failed to become popular with farmers because of the absence of the necessary input supply and marketing infrastructure. This may be crucial for agroforestry because overproduction of wood, fruit or fodder without any market can affect the fanners adversely. The scope for tackling the problems of the rural areas through agroforestry interventions in the Indian subcontinent is very promising. There are a number of indigenous and exotic tree species which are already being grown on agricultural lands. Farmers are responsive to the idea and are prepared to adopt the alternative farming systems. The scarcity of fuelwood and fodder is widespread and is affecting seriously the living conditions of rural people. In such a situation an appropriate technology of tree integration with agriculture will be immediately accepted. However, a major effort awaits agroforestry scientists to synthesize site-specific technology and policy makers to develop a suitable infrastructure for the disposal of diversified products from such a system.
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1 US $ 1 = Indian rupees (Rs) 12.70 (1987). |
