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 Sericulture - Mulberry Cultivation  

1.  SOIL FERTILITY MANAGEMENT IN MULBERRY GARDEN

Sixteen elements are essential for a plant to complete its healthy life cycle. These essential elements are( Where a plant gets its nutrients):

From Air and Water:   Hydrogen, Oxygen and Carbon

From Soil and Fertilizers: a) Primary Nutrients – Nitrogen, Phosphorous and Potassium,b) Secondary Nutrients – Magnesium, Calcium and Sulphur,c) Micronutrients – Manganese, Copper, Chlorine, Molybdenum, Zinc, Iron and Boron. Soil testing is essential to be conducted for mulberry gardens at least once in two years to assess nutrient status, subsequently to add proper fertilizers in adequate quantities. Addition of organic manure can also be calculated based on fertility data. At the time of planting, it is very important to see that the cuttings are placed and the soil around is well compacted. Even the rooted plants obtained from nurseries may also be planted in this manner.

2. RAISING MULBERRY SAPLING FROM HARD WOOD CUTTINGS

In any perennial crop, initial establishment plays an important role in subsequent growth and yield and mulberry is not an exception to this. Mulberry being a vegetatively propagated perennial crop, in commercial cultivation, to perpetuate the parental characters, the mulberry garden is generally established through stem cuttings. Suitable planting methods through cuttings have been evolved for rain-fed system of cultivation. However, due to variation in soil moisture status, fluctuations in temperature and non-adoption of recommended methods of planting by farmers, the initial establishment is not satisfactory and variation in crop stand, large number of gaps, etc., are the common features seen in new gardens. As an alternate method, planting saplings instead of cuttings is very important from the point of above mentioned advantages.

2.1 What is sapling?

Sapling is a rooted cutting of specific age, that is, 100-120 days for low or high bush and about 240 days for small trees. Because of well developed root system, saplings get established quickly and grow vigorously.

2.2 Preparation of nursery bed: A flat land nearer to water source is preferred as nursery site. Well drained land with loamy soil is ideal for nursery. The land must be ploughed or dug 30-40 cm deep and allowed for weathering in sun for 2-3 weeks. Land is again ploughed two or more times to bring the soil to fine tilth. Root stocks, pebbles and weeds should be removed at the time of ploughing and the land should be leveled.

Divide the land into a number of small units to prepare the nursery beds. The size of each bed can be kept conveniently. A bed size of 240 cm (L) x 120 cm (B) can accommodate 180 cuttings (row to row 20 cm and cutting to cutting in a row 8 cm distance) to raise 4 months old saplings. To raise 6 to 8 months old saplings, the same bed can accommodate only 100 cuttings (row to row 30 cm and cutting to cutting in a row 10 cm distance). Each bed on all sides should be separated by a bund of 25 to 30 cm width and height and provided with irrigation channel of 25 to 30 cm width and 15 to 20 cm depth. The following measures are required before planting cuttings in the nursery bed.

  • Add 5 pans of organic manure – FYM/sericulture compost/vermicompost to each bed and mix thoroughly with soil.

  • In the case of clayey or black cotton soil, add 5 pans tank silt or sand per bed and mix with soil uniformly.

  • In the case of red loamy or sandy loam soils, there is a possibility of termite infestation. As a preventive measure, 0.1% Chloropyriphos (5 ml per litre of water) can be sprayed to drench the soil of nursery beds (2-3 litres per bed).

2.3 Preparation of cuttings: Plants selected (any popular mulberry variety) for preparation of cuttings must be healthy and free from scale insect, tukra infestation, etc. the shoots should be 6 to 9 months old and should have attained a thickness of 10 to 15 mm diameter. The stout lower portion and tender, green upper portion of the shoots are not fit to be used as cuttings. The middle portion of uniform thickness must be used. Cuttings for raising 3 to 4 months old saplings are prepared 15 to 20 cm long with 3 to 4 good buds. For raising 6 to 9 months old saplings, cuttings are made about 25 cm size. Sharp knife must be used to get clean cut ends without damaging the bark.

2.4 Transportation of cuttings and storing: Cuttings are to be planted immediately after preparation. Due to unavoidable circumstances, if mulberry cuttings have to be transported over long distance or stored for 2-3 days, the same should be done carefully so that the cuttings do not dry. Keep the cuttings in wet gunny cloth, if they are not planted immediately after preparation. Dressed shoots are preferred for transportation more than whole shoots or stems as such, as the volume can be reduced considerably, than prepared cuttings, which dry too fast. Dressed shoots are transported during cooler hours, especially during night over long distance. Prepared cuttings, if required to be stored, should be bundled with all buds in one direction and kept in wet sand bed with the buds pointing upwards under shade. It can be covered with a thin layer of hay. The sand bed and hay covering must be sprinkled with water daily to avoid drying or cuttings. Cuttings can be stored this way for 2 to 3 days.

2.5 Planting: Nursery beds should be adequately watered and made wet one or two days earlier to planting. Mark each row at a distance of 20 or 30 cm as required, with the help of a thread. In each row by using a pointed stick, make small hole at 8 or 10 cm distance, to insert cuttings. To avoid fungal attack, cuttings may be dipped in 0.2% Bavistin solution for 10 to 15 minutes. Cutting must be planted in the hole in a slightly slanting position, bud turned up, and exposing only one bud above the surface of the soil. The soil around the cutting must be pressed firmly, after planting. In the case of poor rooting varieties, 200 ppm of NAA/IBA dissolved in 90% ethyl alcohol and diluted can be used to treat the cuttings before planting. The cuttings should be dipped in the solution for 6 hours and then used. Cuttings can also be inoculated with VA-mycorrhiza in the nursery bed to get better survivability and economization of phosphatic fertilizer. For this 1.0 kg of soil based VAM inoculum/bed is required. The inoculum can be placed in furrows made for planting cuttings keeping the spacing mentioned above and the cutting can be planted on the inoculum and furrows be closed. By this technique, it is possible to save 75% of phosphatic fertilizer once the plantation is taken up with these inoculated saplings.

2.6 Irrigation: One time irrigation must be provided immediately after planting. Subsequently, irrigation is given once in 4 to 5 days in the case of sandy loam, and red soil once in 7 to 8 days in the case of clayey soil.

2.7 Weeding: Nursery beds must be kept free from weeds. At least two rounds of manual weeding are required, first after 25 to 30 days and second after 55 to 60 days of planting. Only light harrowing using weeding sickle or weeding fork must be attempted, taking care not to disturb the sprouted cuttings. Walking or sitting on the nursery bed should be avoided.

2.8 Fertilizer application: Chemical fertilizer must be applied in the nursery saplings attain 20 to 25cms height in about 55 to 60 days after planting, preferably after the second round of weeding. Following this, 500 g of ammonium sulphate or 250 g of urea can be applied per bed followed by light irrigation.

2.9 Plant protection: The most common disease noticed in nursery is leaf spot. Application of 0.1% Bavistin twice at an interval of 15 to 20 days is recommended. Spraying of 0.1% Rogor to control thrips and 0.1% Metasystax to control mites are also recommended in case such infestation occurs.

2.10 Uprooting, transporting and planting of saplings: Three to four months old saplings are ready for transplantation to establish bush system of plantation. For tree plantation or for raising high bush adopting wider spacing and high crown height, 5 to 6 months old saplings are used. Good saplings attain a height of 90 to 120 cm in 3 to 4 months and about 150 cm in 5 to 6 months in nursery bed.

Before uprooting of saplings from nursery bed, land preparation in the proposed plot should be adequately watered for easy removal. Nursery bed is loosened with the help of crowbar or guddali or pick axe to a depth of 30 cm and saplings are taken out one by one, without damaging the main roots. After uprooting, long time preservation of saplings should be avoided as far as possible and must be taken to the planting site immediately. If long distance transportation is required, saplings must be packed in bundles, covered with wet gunny cloth or green leaves and taken to the planting site during cooler hours. Saplings must be planted immediately after uprooting and as soon as they are received at the planting site, in the pits prepared for regular plantation.

2.11 Kissan nursery: Saplings ensure successful establishment of garden. It is, therefore, a viable proposition to raise saplings on large scale commercially and make them available to farmers. Saplings can be raised directly in flat/raised nursery beds. The production cost roughly works out to be Rs. 0.30 per sapling raised in nursery bed. At selling rate of Rs.0.50 per sapling, Kissan nursery is a quite profitable venture for the farmers. Plan of raising mulberry saplings through Kissan nursery on commercial scale is given in Figure-1.

Figure 1: Seed multiplication programme for mulberry (to cover 2,700/1,227 acres of area)

 

 1.   Two prunings/year – Feb. & June @ 5 tonnes of seed material/year/acre. Total seed material from 72 acres in two prunings.

360 MT

2.       Two prunings/year – Feb. & June @ 5 tonnes of seed material/year/acre. Total seed material from 72 acres in two prunings.

360 MT

3.       Total seed cuttings available from 360 Tones @ 50,000 cuttings/tonne of seed material.

1.80 crores

(say 86 acres)

4.       Total area required for Kissan Nursery @ 2.09 lakh cuttings/acre.

86.1 acres

5.       Total number of saplings available @ 75% survival from 1.8 crore seed cuttings.

1.35 crores

6.       Area coverage by saplings:

     90 x 90 cm spacing with 5,000 saplings/acre.

     60 x 60 cm spacing with 11,000 saplings/acre.

 

2,700 acres

 1,227 acres

3.   TECHNIQUES OF RAISING SAPLINGS THROUGH SOFT AND SEMI-SOFT WOOD MULBERRY CUTTINGS

Low acreage of high yielding mulberry varieties in the field is mostly due to the non-availability of multiplication materials i.e., cuttings. At present, only 6 to 8 months old shoots are used for preparing cuttings. A technology has been developed to use the soft and semi-soft wood green portion of the shoots as multiplication materials. However, soft wood (green) cuttings cannot be planted in the farmers’ field directly or in the regular nursery. Saplings need to be raised in the nursery specially developed for this purpose and 3 to 4 months old saplings can be supplied to the farmers.

3.1 Preparation of cuttings: Prepare 15 to 20 cm long cuttings with one or two top leaves intact. Cut the upper end of the cuttings horizontally above a bud and the bottom obliquely below a bud. Cuttings must be bundled (20 to 30 per bundle) with lower cuts arranged on the same plane. Dip the base of cuttings (2 to 3 cm) in 20 ppm NAA for 24 hours. After washing in water, plant them in the nursery bed.

3.2 Preparation of nursery beds: Select a site with fertile soil and good irrigation facility. Sufficient compost or FYM must be mixed with the soil. Make raised beds of 5 cm high and 120 cm wide. The length of the bed may be kept at 240 cm, but can be made longer as per the requirement and convenience.

3.3 Plantation: Green wood cuttings prepared as above are planted in the nursery bed. It is advisable to plant in the evening to avoid bright sunshine. Cuttings are planted at 8 to 10 cm distance from each other in a row. About 5 cm of the base of cutting is inserted in the ground, shallower the insertion, better is rooting. After insertion, sprinkle water and cover the whole bed, as explained below.

3.4 Covering the nursery beds: Cover the whole bed with transparent polythene sheet supported with bamboo frames in a dome shaped manner to prevent the entry of outside air and to maintain high moisture inside the cover. The height of the cover at the central portion is kept at 50-60 cm above the bed. Above the polythene cover, gunny cloth is spread to serve as sunshade. The ideal temperature for rooting is 25-30˚C with light intensity of 2000 lux. Care should be taken to maintain proper temperature and light intensity. If the beds are not prepared under the shade of tree, provide another layer of gunny cloth on the top.

3.5 Maintenance: Not so much watering is required. If the bed appears dry, irrigate the channel made outside the beds. By seepage, the nursery beds will be moistened.

3.6 Removal of shade: When more than 10 roots per cutting appear, it is the right time to remove the shade. Generally, this condition comes after 35-40 days of planting. While removing the polythene sheet, remove one side one day and the other side on the second day. Fertilizer may be applied on the day of removing the sunshade and 2-3 weeks later. After 3 to 4 months, saplings are ready for plantation in regular plots. The methods are the same for uprooting, transport and planting, as in the case of raising saplings from hard wood cuttings.

3.7 Production cost and economic viability: The technology is to facilitate fast multiplication of the limited availability of seed material of improved mulberry varieties. It also matches where mulberry is harvested by repeated shoot pruning and the plants do not attain the required maturity for raising saplings following conventional system. Commercially, it is possible to raise roughly 1.8 lakh saplings in 1 acre in a year costing Rs.0.40 per sapling.

3.8 Precautions: Do not transport green wood cuttings over long distance, as cuttings will have to be prepared with two green leaves intact, and in as fresh condition as possible.

4. TOP WORKING TECHNIQUE TO REPLACE OLD MULBERRY VARIETIES WITH IMPROVED VARIETIES (OPTIONAL)

Many high yielding mulberry varieties have been evolved recently. The time taken for the establishment of a new mulberry garden is minimum 6 to 8 months and roughly 2 years to come to the optimum leaf yield. The technique of bud grafting or top working can be employed to raise plantation of a high yielding variety (as scion) on the existing plants (stock).

4.1 What is top working?

Top working is a method of grafting a single vegetative bud with a piece of bark as scion, on the stock of existing plant. It is also called bud grafting. Bud grafting is the common vegetative propagation method followed in temperate regions of the country. This is practiced when the scion material is scarce and there are initial establishment problems like poor rooting. The advantages of practicing this method is that, it helps the farmers not to skip too many crops, as the gestation period is comparatively very short. The establishment of the grafted material and the growth is quick enough to compensate the farmer with immediate mulberry crop portion in the existing mulberry garden, depending upon the availability of new variety. However, the limitations are high cost, long time, non-availability of skilled manpower and strict pruning care in subsequent years. Hence, needs precautions.

4.2 Procedure for top working

  • A source for getting adequate number of buds of the new mulberry variety for grafting should be ensured. It is ideal to have a small separate plot of the new variety to ensure this.

  • Existing plantation should be prepared to do top working, by cleaning the garden and removing the thinner branches. The stock branches that are 1.5 to 2 cm in diameter must be selected.

  • Select the required, mature buds of the desired variety.

  • Make a slanting cut with a sharp budding knife, below the bud and lift it upward to about 2-2.5 cm length above the bud and remove the bud gently.

  • In a stock branch, select the internodal smooth portion of stem at height of 25 cm, only to a bark depth. Give another cut horizontally at the top of the vertical cut, which now appears as a ‘T’ mark.

  • Gently lift the bark pieces on either side of the vertical cut for inserting the bud of the new variety, which is separated and kept ready.

  • Insert the bud of the improved variety in the ‘T’ cut of the stock and tie the union tightly with polythene strip, exposing only the bud.

  • After bud grafting, cut the stock branch a little above the grafted level.

  • Irrigate the plot till sprouting of the grafted bud is ensured.

  • Remove the sprouting shootlets of the old variety, regularly. Allow the growth of the grafted buds only.

4.3 Precautions

  • Basal pruning should be done always above the grafted level.

  • Shootlets of the stock (old variety) should be removed whenever such sprouting occurs.

5.  PACKAGE OF PRACTICES FOR MULBERRY CULTIVATION UNDER RAINFED CONDITION

Mulberry can be cultivated both under soil moisture stress (semi-arid or rainfed) and irrigated conditions. Specific package of practices for mulberry cultivation has been developed aimed at improving both the leaf yield and quality under such stress conditions of rainfed regions.

Package of practices mainly involve use of high yielding mulberry varieties like S-13 in red loamy soils and S-34 in black cotton soils, which are adapted to stress conditions. Measures for better establishment during initial stages of plantation and suitable agronomical practices emphasizing soil moisture conservation and timely plant protection measures are essential.

5.1 Establishment of mulberry garden: Mulberry is a perennial plant. Once it is properly raised during the first year, it can come to full yielding capacity during the second year and last for 15 years in the field. There fore it is very important to estalish the crop initially according to the scientific methods to obtained best results. To get better mulberry productivity, following package can be adopted:

5.2 Selection of land: Flat or slightly slopy land is suitable for mulberry cultivation. More slopy or steep lands need proper soil conservation measures through bench terracing, contour bunds and drains. Though mulberry can be grown practically in a wide range of soils, loamy to sandy loam and clayey loam soils are preferred. In the case of acidic (pH < 6.5) and alkaline (pH > 7.5) soils, necessary corrective measures should be followed through lime or gypsum application, respectively. Mulberry is a deep-rooted plant and the top soil should be sufficiently deep (60 to 90 cm).

5.3 Preparation of land: Planting should be undertaken during the commencement of South West monsoon. Therefore, land preparation should start in pre-monsoon period. Deep digging or ploughing of land to a depth of 30 to 35 cm is recommended, prior to the dry season, making use of the available soil moisture. The field is then left exposed during the summer, in order to kill weeds and soil-borne insects. During the pre-monsoon showers, the soil lumps must be broken and the land must be ploughed repeatedly to bring the soil to a fine tilth. The land should be leveled, and divided into plots of convenient size providing the contour bunds for proper harvesting of rain water.

Pit system of planting with wider spacing should be adopted for rainfed mulberry. Pits of the size 35 cm (L) x 35 cm (B) x 35 cm (depth) are dug at 90 x 90 cm spacing. Pits are then filled with a mixture of soil and FYM (2 kg of FYM/pit). One can use Sericultural compost or vermicompost in the pit to get better results.

5.4 Planting material and planting: Varieties S13 and S34 are recommended for rainfed conditions. Generally, mulberry cuttings are used for planting, but planting saplings is better. Branches of 8 to 10 months old and 10 to 12 mm diameter are selected for cutting preparation. Each cutting should be 20 to 22 cm length with minimum 3 to 4 healthy buds. The cut should be clean without damaging the bark or wood. Greenish tender portion or too thick lower portion of the branches should not be considered for preparation of cuttings. Three cuttings are planted in each pit with a spacing of 15 cm between cuttings, in a triangle. Cuttings are placed deep, leaving just one bud on top, 2 to 3 cm above the ground and the soil around each cutting should be pressed well to keep the cuttings firm in the soil.

It is risky to resort to direct planting of cuttings, under rainfed conditions. It is ideal to use 4 months old saplings (one sapling/pit) under such condition and support it with pot watering during initial period of establishment. Planting can be timed to receive adequate rainfall for 1 to 2 months period to the advantage for higher survival, quick establishment and maximum growth of plants.

5.5 Initial care and fertilizer requirement: When the new garden is 2 to 3 months old after planting, inter-cultivation is done by weeding through light digging of the soil and applying the first dose of NPK @ 25 kg/ha through any complex fertilizer-Suphala/Vijay. Weeding is again done after another 3 months of first weeding, followed by application of second dose of nitrogen @ 25 kg/ha either in the form of urea or ammonium sulphate. This would enable the plants to grow well and establish fully. Though the plantation may give enough foliage by the end of 8 to 10 months, it is advised not to take early leaf harvests before the plants attain full growth, which takes roughly one year under rainfed condition. The first pruning is done in the following rainy season, after one year. The plants are cut at a height of 8 to 10 cm above ground level, with a sharp pruning knife or saw without damaging the stem. Systematically cultivation practices must be followed from second year of planting. Ready reckoner for fertilizer requirement for rainfed mulberry is given in Table 1.

5.6 Maintenance of rained Mulberry Garden:The scheduled of systematic cultivation practices for maintenance of rainfed mulberry garden from second year of planting is given in the following table

Table 2: Scheduled of systematic cultivation practices for maintenance of rainfed mulberry garden

5.7 Leaf yield: By adopting the package of practices for the rainfed mulberry garden, it is possible to harvest 7 to 8 MT of leaf per hectare per year during the second year of establishment and 10-12 MT of leaf per hectare per year from third year onwards.

6.   AZOTOBACTER BIOFERTILIZER FOR MULBERRY PLANTS

The high fertilizer requirement in mulberry cultivation in mulberry cultivation especially nitrogen (300 kg N/ha/year) is leading to increased cost of its cultivation. Fertilizers are not only in short supply, but also expensive and not available in time. Small and marginal farmers who cannot manure their garden in time in adequate quantity often harvest poor cocoon crop. Azotobacter biofertilizer, a cost effective supplement to chemical nitrogenous fertilizers in mulberry cultivation, is recommended to make sericulture more profitable. Besides, it reduces the deleterious effect of chemical fertilizers on soil health and also reduces the water pollution from nitrate contamination through leaching.

6.1 What is Azotobacter biofertilizer?

It is a bacterial preparation of live Azotobacter cells blended with suitable carrier material like lignite/peat in powdered from. It is capable of supplying nitrogen to the plants through biological nitrogen fixation and enhances plant growth. It is available in small polythene packets weighing generally 150-200 g and can be easily handled.

6.2 Recommendation

  • Apply 20 kg Azotobacter biofertilizer/ha/year (to compensate 150 kg nitrogen) in 5 split doses @ 4 kg each time after every leaf harvest/pruning and intercultural operations.

  • Use phosphorous and potash @ 120 kg/ha/year each in 2 split doses, as per recommendation for irrigated mulberry.

  • Farmyard manure (FYM) should be applied @ 20 tonnes/ha/year as recommended for irrigated mulberry.

  • Apply only 150 kg nitrogen./ha/year instead of 300 kg nitrogen in 5 equal split doses @ 30 kg each time after every leaf harvest/pruning and intercultural operations.

6.3 How to use biofertilizer?

  • Biofertilizer should be used before/after application of chemical fertilizer over a gap of at least 10-15 days.

  • Before use, biofertilizer should be mixed thoroughly with dry powdered FYM (4 kg biofertilizer + 200 kg FYM each time) and applied in between the rows of mulberry making furrow.

  •  Furrows should be covered immediately after application.

  • Irrigation should be given immediately after application of biofertlizer.

6.4 Precaution

  • Never mix chemical fertilizer with biofertilizer

  • Keep biofertilizer away from heat and direct sunlight and use it before its expiry date.

  • After application, land must be irrigated adequately and immediately to save live bacterial cells from desiccation.

  • Collect biofertilizer from authentic sources to avoid spurious material.

6.5 Advantages

  • Eco-friendly and reduces ill-effect of chemical fertilizers on soil health.

  • Long lasting effect and sustainability.

  • Cuts down cost by 50% in the total application of nitrogen fertilizer, thereby reducing, at least Rs.700/- per hectare per year, on fertilizer cost alone.

7.   PREPARATION OF COMPOST USING SERICULTURAL WASTES

Good quality farmyard manure is perhaps the most valuable organic matter applied to soil to enhance soil fertility and to increase micronutrients, which are essential for plant growth. Generally, in sericulture farms, the left over mulberry leaves from rearing bed and field and other waste including silkworm litter are not properly utilized in preparing compost of high nutrient value. The traditional method of preparation of compost is generally not effective. The loose heaps lie exposed to the sun, with the result the raw organic matter dries up quickly and does not decompose properly. Hence, it is essential to convert the sericultural farm wastes into valuable compost, adopting suitable technology.

7.1 Preparation of compost: The mixed farm wastes can be collected in pits of a convenient size. Pit size of 3 x 1 x 1 m is adequate to receive farm waste from 1 acre garden from roughly 2 harvests in 4 to 5 months time. Two such pits made side by side can be used alternately to compost all the farm waste from one acre mulberry garden. Each day’s collection of various sericultural wastes like silkworm litter, left over mulberry leaf, weeds, etc. should be spread in a thin layer sprinkled with a layer of fresh cow dung, ashes and water and compacted. At the end of the rearing, the left over leaves in the garden, along with the young mulberry twigs can also be added to the pit. Some quantity of chemical fertilizer specially Superphosphate is also added to enrich the compost When the pit is filled and the bed stands 30 to 45 cm height above the ground level, it is then plastered with a 2.5 cm layer of a mixture of mud and cowdung. A thatched shed should be provided to protect the compost pit from rain and direct sunlight. To enhance the decomposition process, lignocellulose decomposing fungi like Aspergillus sp./Trichoderma sp./ Belaromyces sp. could also be added along with organic wastes.

7.2 Process of decomposition: Under above conditions, decomposition is anaerobic which is mainly a reduction process and high temperature is not generated. The plant remains, silkworm litter and cattle dung contain water, carbohydrates, organic acids, lignins and mineral constituents like phosphates, silicates, etc. during the process of composting, these are attacked by variety of microorganisms like bacteria, fungi, actinomycetes, protozoa and worms. As a result of their activities, considerable portions of the residues, notably the carbon, nitrogen, phosphorous and potassium are rapidly liberated in available form for plant growth and well decomposed bulky organic matter is produced. The rate of decomposition depends upon the nature of the residues and upon the conditions under which decomposition takes place. During this process, organic nitrogen is reduced to organic acids and ammonia. The heat generated is sufficient to destroy all the harmful pathogens present in the material. The nutrient content of various organic manures is given in Table 2

Nutrient content of various organic manures (on air dry basis)

7.3 Conditions required for satisfactory decomposition

  • An adequate supply of available nitrogen in the form of organic wastes.

  • Adequate moisture. Low moisture (10% and less) arrests the activities of most cellulose-decomposing organisms while high moisture content (80-95%) promotes anaerobic bacteria at the cost of fungi and most actinomycetes.

  • A fine state of mechanical disintegration.

8.  RAISING MULBERRY GARDEN exclusively for YOUNG AGE (CHAWKI) SILKWORM REARING

Among the several factors that contribute to successful young age silkworm rearing, supply of highly nutritious mulberry leaves as feed is a vital one. The larval period and its maintenance is of utmost importance for the success of sericulture industry since it is the only feeding stage of the insect. The qualitative and quantitative requirements of the feed for silkworms differ at different stages of larval period. While it is generally established that the young age silkworms require mulberry leaf of higher succulency, moisture and nutrient contents, the late age worms feed on coarser leaf with less moisture content. Other important factors determining the success of cocoons crop are the health, care and hygiene during the young age silkworm rearing-popularly called the “Chawki Rearing”. Though importance of chawki rearing has been realized and several Chawki Rearing Centres (CRC) have been established to serve farmers, the problem of producing quality leaf in adequate quantity for chawki rearing centres has not been met successfully. To meet the suitable leaf requirement for exclusive Chawki centres any one of the training methods explained below may be adopted.

8.1 Eight harvests schedule per year

8.1.1 Selection of site and land preparation: Selection of site for establishment of the chawki mulberry garden is very important. The site must be more or less flat and in an elevated place, light textured, deep, sandy loam or clayey-loam soil. Site must be free from nematode and termite infestations and should not be low lying areas with excess soil moisture. The ideal spacing to be adopted is 60 x 60 cm.

8.1.2 Training schedule: After an establishment period of about one year, the plants should be pruned at crown (20 cm above ground) during onset of monsoon. After 35 days of bottom pruning, harvesting of leaf is commenced for next 10 days (up to 2nd moult). At the end of rearing, the top terminal bud is to be clipped. Twentyfive days after top clipping, second leaf harvest as shootlets is to be done for rearing of worms up to second moult. Thereafter, plants are again pruned at crown (80th day after 1st pruning). This cycle has to be repeated 4 times to get 8 crops in a year. Thus, plants are pruned at the crown (20 cm above ground level) 4 times in a year (after 2nd, 4th, 6th and 8th crops). Individual leaf picking is recommended for 1st, 3rd, 5th and 7th crops while the shootlets are to be harvested in 2nd, 4th, 6th and 8th crops for the purpose of rearing.

8.1.3 Manure and fertilizer schedule: The annual dose is 40 MT FYM/ha to be applied in two equal splits in 1st and 5th crops. The annual fertilizer dose is 225:150:150 NPK kg/ha in 8 equal splits @ 28:19:19 kg NPK/ha/crop. This can be applied as 127 kg Suphala 15 N: 15 P: 15 K plus 20 kg urea per crop.

8.1.4 Irrigation: 1.5 acre inch of irrigation water is to be provided once in 4-6 days by ridges-furrows method (34,000 gallons of water per acre each time)

8.1.5 Advantages

  • Leaf yield: The above technology ensures a high yield of 29 MT of chawki leaves per hectare per year as against 7 MT/ha of chawki leaves obtained from common gardens. Almost 100% of the leaves produced are suitable for chawki rearing.

  • Leaf quality: Qualitatively the leaves produced by this technology are superior (about 80% leaf moisture, and by dry weight 25% of leaf protein and 13% of leaf sugar) to leaves obtained from common garden (76% leaf moisture, and by dry weight 21% leaf protein and 11% leaf sugar).

8.2 Twelve harvests schedule per year: Establishment of mulberry garden on sound footing is a prerequisite for sustained yield of quality leaves per unit area over several years. Regarding this, the following activities must be carried out systematically.

8.2.1 Selection of site: The site must be more or less flat and in an elevated place, light textured, deep, sandy loam or clay loam soil. Site must be free from nematode and termite infestations. It must have an assured source of irrigation.

8.2.2 Land preparation: After selecting the site, the land must be given deep ploughing/digging. The weeds, root stocks and boulders must be removed. It must be allowed for weathering for about a month. The ideal soil pH range is 6.5 to 7.0. If the soil pH is above or below the desirable level, corrective measures may be adopted by applying required quantity if lime to acidic soil or gypsum and green manure to alkaline soil. In this context, soil analysis assumes special significance to test the fertility and pH of the soil. The organic carbon content should be more than 1%; adequate quantity of organic matter should be incorporated in deficient soils. Entire land can be divided into smaller plots of convenient size with provision for irrigation channels and bunds.

8.2.3 Spacing: Spacing for planting the saplings should be 60 cm between the rows and 60 cm between the plants in a row (60 x 60 cm). With this spacing, about 10,000 saplings can be planted in an acre (0.4 ha.) of land.

8.2.4 Planting material: Healthy, 100-120 days old saplings of 80-90 cm height can be used for planting. Because of already developed root system in saplings, plants get established quickly and grow vigorously.

8.2.5 Planting: Planting work can be taken up soon after the onset of regular South West monsoon. One sapling per pit be placed deep and straight in the pit/trench by removing the soil. After this, the soil around the sapling must be pressed firmly. When planting work is over, adequate irrigation has to be given immediately and in the event of failure of rain.

8.2.6 Intercultivation and maintenance during establishment: About 1˝ months after plantation, alight weeding/hoeing must be done. Second weeding must be done around 3 months of planting. Weeding operations must be thorough and should be regularly carried out.

The plantation taken up during the monsoon period will have the advantage of receiving fairly distributed rain from June to October. If there is no rain or not adequate for a period of over 10 days, supplemental irrigation has to be given. After the cessation of the monsoon, irrigation has to be given regularly at an interval of 6-7 days, but this frequency varies depending on weather conditions and types of soil. About 1.5-2.0 acre inches (34,000-45,000 gallons) of water is required per irrigation. Irrigation can be given by furrow system and whenever possible, drip or sprinkler system can be adopted.

Mulberry grows vigorously under assured irrigation and soil fertility. First dose of chemical fertilizer should be given as booster dose at the rate of 50:50:50 kg NPK/ha after second weeding and 3 months of planting. By sixth month, plants would be ready for first harvest of leaves. After the first light harvest of leaves followed by weeding, a second dose of chemical fertilizer must be applied at the rate of 50 kg/ha.

In the interest of good establishment of the plantation, it is not advisable to go for regular leaf harvest till the completion of one year of planting. After 6 months of planting, 3 light leaf harvests can be made till basal pruning is taken up.

In the event of occurrence of fungal diseases, spraying of 0.1% Bavistin and in case of attack of insect pests, spraying of 0.1% Metasystox has to be done. Care should be taken to allow required safety period before harvesting leaf for brushing.

8.2.7 Management of established garden and leaf harvest: About one year of planting, with good maintenance, plantation will be established well. Following the good establishment, regular management and leaf harvests can be initiated. The aim of developing exclusive chawki mulberry garden is to get suitable nutritious leaf for chawki rearing continuously. In this direction, the following cultural operations must be carried out systematically.

  1. Pruning: The first basal pruning must be at 30 cm above the ground, preferably during the onset of South West monsoon. Following the first basal pruning and 3 leaf harvests, at an interval of 15 days, first middle pruning at 60-70 cm above the ground has to be done. Following this, 3 more leaf harvests can be made. Again the same sequences will follow. Totally 2 basal pruning and 2 middle cuts must be done in a year. After about 20 days of each pruning, weak branches can be removed.

  2. Weeding and digging: After thorough weeding, digging must be done to loosen the soil, to stimulate the plant growth and to facilitate the application of manures. Following digging operation, ridges and furrows should be formed.

  3. Manuring: Yearly twice, bulk organic manure in the form of farmyard manure or compost should be applied at the rate of 15 tonnes/ha/time and incorporated into the soil. This may be carried out within 15 days of each basal pruning. Thereafter (8-10 days), application of chemical fertilizers should follow. The total annual requirement of chemical fertilizers is 240: 140: 140 kg NPK/ha. The fertilizers should be applied in 4 equal split doses corresponding with 2 basal and 2 middle pruning.

  4. Irrigation: In light sandy loam soils, more frequent irrigation at 6-7 days’ interval may be found necessary, while in heavy clay loam soils, irrigation at 8-10 days’ interval may be found adequate. It is also important that at the above intervals of irrigation, adequate quantum of water should be supplied as irrigation at a time. It has been estimated that 1.5 to 2 acre inches of water is required per irrigation.

  5. Plant protection: To improve the leaf quality as well as the productivity, whenever necessary, plant protection measures must be followed. But, these measures can be taken up only after pruning and 15 to 18 days before leaf harvest for brushing.

  6. Leaf harvesting and preservation: From brushing to two feedings after second instar, the silkworms are fed with young leaves. The leaves to be harvested are from below the largest glossy leaf, which is yellowish green in colour. The cardinal point is shoot tip and it should not be removed during any crop. Below the glossy leaf, about 3 leaves during the first (1-3) and about 3 leaves (4-6) during the second instar can be harvested. Usually in cool hours (morning and evening) harvesting has to be done. While harvesting, care must be taken not to damage the shoots. Due attention must be given to harvest required quantity of leaves in the shortest time possible from the plot and to bring that to rearing house immediately. Excess leaf harvest and longer preservation must be avoided.

Silkworms grow best when fed with fresh mulberry leaves, which are rich in nutrients and moisture. Under tropical conditions, driage of leaf is faster. Usually, the leaves are harvested twice a day and are preserved for successive feedings, depending on the necessity. During this period, the leaves should be preserved in cool and clean places in order to preserve their succulency. It is batter to preserve leaves in a leaf chamber or bamboo basket which is lined with gunny cloth, that can be kept wet by sprinkling water at frequent intervals. Harvested leaves must be sprinkled with water in summer season, if necessary. Alternately, chawki mulberry leaves can be stored in a mud pot, which is placed in the moist sand and mouth of the pot must be covered with wet cloth. Also, chawki mulberry leaves can be stored on a flat moist sand bed covered with wet and clean white cloth. Again after arranging the leaves on the sand bed, they must be covered with wet white cloth.

8.2.8 Economics: To work out the economics of chawki leaf production, three models of 0.2 ha (yearly 5,000 kg leaf and 30,000 Dfls), 0.4 ha (yearly 10,000 kg leaf and 60,000 Dfls) and 0.8 ha (yearly 20,000 leaf and 1,20,000 Dfls) have been considered. This consideration is based on availability of 10,000 kg leaf/0.4 ha (1 acre)/year by 12 crops. Also, as 15 kg leaf requirement/100 Dfls. The cost of chawki leaf production works out to be Rs 2.60 per kg, with depreciation and Rs.1.77 per kg without depreciation.

8.2.9 Leaf yield: This method will ensure roughly 25 MT of chawki leaf per hectare per year in 12 harvests. All the leaves produced are fit for chawki rearing, unlike in regular mulberry garden where only about 20% of the total leaf yields is fit for chawki rearing, which is about 7 MT per year per hectare. Leaf yield in exclusive chawki garden raised is adequate to rear 1,20,000 layings per year per hectare.

8.2.10 Leaf quality: Qualitatively the leaves produced in chawki garden are far superior with 75 to 80% moisture content, and by dry weight basis 25% leaf protein and 13% leaf sugar to leaves obtained in general commercial garden, with 70 to 74% moisture content, 20 to 21 leaf proteins and 11% leaf sugar.

8.2.11 Is it possible to convert a portion of the existing garden into chawki plot?

The aim in raising exclusive chawki garden is to maximize chawki leaf production per unit area and improve the leaf quality for Chawki Rearing Centres. However, there are thousands of farmers to whom CRC facility are yet to reach or are confident to do themselves the chawki rearing scientifically. For such individual farmers, improvement of chawki leaf quality is the prime concern than increasing the quantum of production. Such farmers can mark a small portion of the existing garden (roughly 5% of the garden) and provide additional input of FYM, irrigation etc.

   

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