Developing Tea-based Crop Model in Wasteland of South Bengal forHigher Income Generation

S. Palit1*, B. C. Ghosh2

and K. K. Bhowmik3

Introduction

In West Bengal, tea is grown under high rainfall on slopes of hills or high plateau in thedistricts of Darjeeling and Jalpaiguri. In recent past, tea cultivation is expanded in marginaland fallow lands in non-traditional areas. Tea as a perennial crop prefers to grow in deepfertile well drained and acidic soil. Its cultivation is also attempted in southern part of WestBengal at village Gopali of District West Midnapore and a new crop model was developed.

Methodology:

The lands were divided into series of plots of 50 m in length and 18 m in width. The soilwas deep ploughed, levelled and maintained a gentle slope (about 1 %) towards the drainagechannel at both sides of each plot. Drainage channels of 75 cm deep and 50 cm wide weredug to prevent water logging. The field layout was done by staking and making pits of 45 cmx 45 cm size. Each pit was filled up with soil and organic fertilizers. Planting was done at aspacing of 100 cm between rows and 75 cm between plants. Six improved tea clones, TV1(quality clone), TV9, TV22, TV 23, TV 25 and TV26 (productive clones), were planted indifferent plots in 20 acres.

Shade is an integral component of tea ecosystem comprising tea plants, shade trees and greenmanure crop to maintain optimum level of light intensity, temperature and relative humidity.The shade tree species considered for plantation were Albezia lebbek (siris) and Leucaenaleueocephala (subabool) as woody tree, Psidium guajava (guava), Achras zapota (sapota)and Emblica officinale (aonla) as fruit trees and Santalum album (sandal wood) were grownin different plots. Besides, spices Piper nigrum (Black pepper) as climber and Zingiberofficinale (ginger), Curcuma longa (haldi) and Ananas comosus (pineapple) were grown asborder crops. The spacing of shade trees was 6 m x 6 m between rows and plants. The greenmanure crop Sesbania sp (dhaincha) was sown after every 2 rows of tea to provide temporaryshade to tea to provide temporary shade to tea crop at initial growth stage as well as to enrichsoil fertility.

Fertilizer management:

An attempt was made to produce organic tea for which organic and natural sources offertilizers and pesticides were used. At planting vermicompost @ 4 kg and 40 g ofrock phosphate were applied in each pit as basal dose and were mixed thoroughly withsoil.

1*corresponding author: Dr. Soumen Palit, Director, Eco Yes Technologies, Science and TechnologyEntrepreneurs Park, IIT Kharagpur, West Bengal – 721 302, email:psoumen@gmail.com2Dr. B. C. Ghosh, Professor, Agricultural and Food Engineering Department, IIT, Kharagpur, West Bengal –721 302, email:bcg@agfe.iitkgp.ernet.in3 Dr. K. K. Bhowmik, Agriculture Officer, West Bengal Comprehensive Area Development Corporation,email: kanchanbhowmik30@yahoo.com

In subsequent years, year –wise fertilizer schedule as per standard nutrient requirement ofcrop on N equivalent basis was followed (Table -1). The vermicompost was applied astopdressing in four splits in a year and mixed well in soil.

Table -1

Year Vermicompost(tonnes/ ha)

N equivalent(kg)

01+2+3+4+

2.214.435.536.648.31

4080

100120150

Year wise fertilizer schedule at young tea stage

Water management:

Tea is very sensitive to both excess and deficit soil moisture (stress) condition. During dryseason, irrigation was optimized through sprinkler irrigation system. This system is alsocongenial to create microclimate for tea during hot dry months and also help to reduceseasonal dormancy for sustained productivity. During rainy season, adequate drainage facilitywas provided to remove excess water as tea is susceptible to waterlogged condition.

Debudding and pruning:

Debudding and pruning were done to maintain convenient height of tea bush to facilitateplucking operation. It is aimed to check reproductive growth and simulation of vigorousshoot system and maintaining sufficient volume of maintenance foliage to meet thephysiological needs of plants. During zero year, six weeks after plantation, all axillary budswere removed leaving 9 inches from the ground level and also simultaneously shoot tips.This practice encourages formation and growth of lateral shoots at base of plants.

Therefore, plants were allowed to grow up to 24 inches from the ground level and tipping ofshoot tips was done regularly. During 1 + year, out of developed branches, the leader wasremoved leaving 11 inch from the ground level. This practice helps in uniform growth anddevelopment of all the branches. At the end of 1 + year, the first frame forming pruning wasdone by removing all branches leaving 14 inch from the ground level by using a pruningknife.

Thereafter, new shoots were developed and were allowed to grow up to 10 inch from pruninglevel and removal of young shoots was continued. During 2 +year, removal of young shootscontinued and bush height of 24 inch was maintained. The second and final frame formingpruning was done at 3 + year by removal of all branches leaving 16 inch from ground leveland the new shoots were allowed to grow up to 10 inch from pruning level. In subsequentyears, light pruning, medium pruning, collar pruning, deep skiff, medium skiff, etc., werepractised in a time scale as per age of the bush.

Tipping and plucking:

Tipping is an essential operation aimed at formation of a level plucking surface and to inducebranching at a high level which produces more plucking point bushes. Plucking is mostimportant harvesting operation and intricately related to pruning and tipping. In plucking,tender apical terminal buds and two expanded leaves are considered. A uniform pluckingtable of about 50 cm diameter at 3 + year was developed by regular harvesting of two leavesand a bud at 7 days interval.

Yield:

During 3 + year, yield assessment of made tea was done after processing of harvested leaf. Atotal yield of 1,100 kg/ ha of made tea was achieved. Besides, 3.5 tonnes/ ha of guava and175 kg/ ha of ginger, respectively were obtained. The fruiting in aonla, sapota and other cropswas recorded in subsequent years.

Nursery management:

For promoting tea cultivation in South Bengal, availability of planting material of goodquality clones at growing site is of vital importance. In this respect a seedling raisingtechnique and nursery management have been standardized. Vegetative propagation of teaplants by means of stem cutting was attempted successfully and polythene sleeve nurserytechnique was adopted for the same. For mother bush, a section of tea plantation area waskept unpruned for each tea variety.

The stem cuttings were used as planting material. The cuttings of 3 -5 cm long and 3- 4 mmin diameter were treated with IBA and planted in polythene sleeves of 7 inch in length and 4inch in diameter which were filled up with soil of pH 4.8. The polythene sleeves were placedunder shade net (30 % infiltration of light). The seedlings were grown for a period of 8months with a survival rate of 88 %.

Processing and quality assessment of tea:

After harvesting of tea leaves, tea was processed in steps, i. e. Withering –rolling –fermentation-drying – grading. A miniature tea processing plant is established at IIT,Kharagpur, by installing withering through rolling machine, fermentation floor, drier andshorting machine.

Withering: In withering, initial moisture content of plucked leaves is brought down to 60 -65%. Different physico-chemical changes in leaves increase cell membrane permeability,initiation of polyphenol oxidase/ peroxidise activity, breakdown of chlorophylls and proteins,degradation of carbohydrates, increase in caffeine and inorganic phosphate contents anddevelopment of flavour volatiles. The leaves are spread uniformly on withering trough and airblown for removal of moisture. The leaves are allowed to wither for a period of about 12 – 14hours depending on initial moisture content in leaves.

Rolling: The leaves are macerated so that enzymes and their substrates got intimately mixedup. The treatment also allows maximal availability of polyphenol oxidase duringfermentation as the enzyme is located in leaf epidermal cells and also produce flavourcompounds and degraded chlorophyll. During rolling, cell wall of leaves is ruptured andthereby enabling the production of enzyme. The rolling process is continued for 45 minutes.

Fermentation: Fermentation involves oxidation of polyphenols by polyphenol oxidase. Theprocess involved spreading the macerated leaves uniformly in a layer of about 6 cm for aperiod of about 2 hours on fermentation floor. During this process, polyphenols are oxidizedand then condensedto form theaflavins, thearubigins etc. The chlorophylls are degraded andsome of flavour components are produced from lipids, amino acids, carotenoids andterpenoids. The outcome of fermentation process is development of colour strength andquality of made tea.

Drying and grading: In drying, moisture content of rolled and fermented leaves is reducedfrom 45 – 50 to 3- 4 % level in dried black tea. Drying is achieved by blowing hot air of 87°to 93° C at the inlet and 56° C at the outlet. The drying process continues for 20 minutes.During drying, inactivation of enzymes, loss of soluble solids, development/ loss of someflavour components and conversion of chlorophyll to phaeophytin responsible for blackappearance of manufactured tea are important. Grading and sorting are done by gradingmachine into different grades of made tea. The different grades are designated as brokenorange pekoe, broken pekoe, orange pekoe, fannings and dust based on relative proportion ofparticle size.

Quality assessment: Polyphenols and caffeine are important indices for judgement of teaquality. Among polyphenolic compound catechin content is estimated at 2.03 – 2.24 %indifferent varieties tested. Caffeine is an important chemical present in made tea. Generally,tea leaves contain about 4 %. Among test varieties, TV 26 had highest caffeine content. Insensory evaluation the processed made tea by orthodox method is judged by tea taster to bestandard quality tea.

Conclusion:

The developed crop model by growing tea-horticulture-spices together in a multistoriedcropping system can be transferred and adapted in large tracts of marginal wasteland in acidlateritic soil belt of South Bengal. There would be a gain in income and employmentgeneration for small and marginal group of farmers. Moreover production of organic tea andother organic product from same cropping system received high market value. There is gainin buildup of soil fertility by introduction of the crop model in marginal wasteland.