Rice

Harvesting & Storage

Drying

• Drying is a process which reduces moisture content from grain to safe limit.
• Drying process is basically the transfer of heat by converting the water in grain to vapour and transferring it to the atmosphere.
• Threshed paddy or boiled paddy required drying.
• It is essential that drying is gradual and slow in the initial stages in order that the milling quality is not adversely affected.
• When paddy is relatively dry, it can be dried further rapidly without damaging the grains.
• High moisture in the grains as well as high humidity in the atmosphere cause sprouting and molding of grain.
• This problem can be overcome by mixing powdered common salt at 5 Kg/100 Kg of grain.
• The salt absorbs water from the grain and salt solution flows out of the heap of grain.
• This treatment prevents heating and subsequent damage to the produce.
• Another way of storing wet paddy is by mixing paddy husk, which helps in storage for about seven days.
• Artificial drying by using the steam to dry the produce, can be done at any time of the year, but is expensive.
• Timing Dry paddy as soon as possible to 18% moisture content to decrease discoloration, spoilage and sprouting.

Moisture content target

• Do not dry below 14% MC - unless for long term seed storage - over dried grain will crack upon readsorbing moisture from the atmosphere and thus will have a lower head rice recovery when milled.
• Do not mix grain of different moisture contents as this causes moisture absorption by the dry grain and results in grain cracking.

Drying temperature and rate

• Set operating temperature initially at 150 °F (65 °C).
• As the grain dries out, or when moisture has dropped to 18%, turn down drying air temperature to 110 °F(43 °C) to prevent fissuring of the grain.
• At 65 °C, the drying rate is about 1% moisture per hour.
• At 43 °C, the drying rate is about 0.5% to 0.75% moisture per hour.
• If there is no great urgency, fuel costs can be reduced by using ambient air (if relative humidity is less than 70%), once the grain moisture has reached 18%.
• Then, slow dry the grain with ambient air until moisture reaches 14%.
• Drying Options - flat bed dryers, recirculation dryers, sun drying.
• Drying is done either by using : Solar energy or by Artificial heating.

Sun Drying

Sun-drying is carried out by the farmers on public roads or on made-up floors under uncontrolled conditions. Rice millers invariably use concrete floors for drying. Such drying results in sun-cracks and contamination on quality of rice is little realised as much of the milling is in hullers which by themselves contribute to breakage. Dependence on sun for drying also means break in operations when sun is not available.

• In case of sun drying the produce is spread on hard floor or threshing yard around 10-cm thickness, and is allowed to dry by heat supplied by the sun.
• If high moisture continues to remain in rice after harvest, it would undergo spoilage because of high temperature, respiration rate and microbial activity, and the presence of foreign matter.
• Hot spots often develop in concentrations of foreign material.
• In general, four to five days of sun drying is required for different produce to bring the moisture to a safe level.
• In tropical regions, one-day drying under full sunshine throughout the day brings down grain moisture content of rice from 24 per cent to 14 per cent.
• Though sun drying is cheaper, there are some problems.
• The grains that are in the upper layers develop fissures due to uneven sun-drying resulting in broken grains.
• However, this problem can be overcome by repeated stirring.

Artificial Drying methods

• Flow drier heated by paddy husk.
• Batch drier heated by either furnace oil or paddy husk.
• Mobile driers heated by paddy husk.
• Unheated air drier.
• Portable driers is a recent development.
• Bagged raw paddy or paddy in bulk can be dried with these driers by keeping the air temperature at 55 °-60 °C.
• It takes about 1 hour for reducing the moisture by 2 per cent from 22 per cent and later on one hour for every one per cent.
• The driers being portable, handling and transport costs are considerably reduced.
• Avoid grain from overheating. Drying for seed

Timing

• Dry paddy to 18% moisture content as soon as possible (especially during periods of inclement weather, and when grain has moisture above 21%) to decrease discoloration, spoilage and sprouting.
• Moisture content do not dry below 14% MC - unless for long term seed storage - over dried grain will crack and re absorb moisture from the atmosphere and thus will have a lower head rice recovery when milled.
• Drying temperature and rate Drying at 110 °F (43 °C)
• The drying rate of a flatbed dryer is about 0.5% to 0.75% moisture per hour.
• If the initial moisture content is 21%, it will take about 10 to 14 hours to dry the grain to 14%.
• Dry the grain continuously until moisture of grain near the blower end of bin has reached 14%.
• If blowers are delivering the correct air volume, it is not necessary to mix the grain.
• However, more uniform drying can be attained if the grain is mix at least once, halfway during the estimated drying period.
• Monitor the drying progress with a moisture meter.

Drying options

• Flatbed dryers, recirculation dryers, sun drying
• Seed purity : Maintain genetic purity by preventing mixing or contamination with other seeds.
• Clean and grade seed to produce uniform sized seed grains.
• Storage : Store seed and protect it, if necessary from bacterial and fungal growth, and infestation by mites and insects with the proper seed protection chemicals.
• Hygeine about the seed storage area is critical.

Storage - Principles

• Rice is stored in the forms of paddy or rough rice, milled raw rice, milled boiled rice, bran, broken grain either on the farm or in the mills and in commercial warehouse.
• Paddy is stored either for seed or for hand pounding or for milling as needed.
• Rice (husked rice), either semi-polished (4-5% removal of bran) or polished (10 - 12 % removal of bran), is stored in jute bags.
• According to the consumers' liking the raw rice has to be stored for at least over a year before it is consumed while with parboiled rice no such condition is needed and is consumed as fresh.
• In store the rice develops rancidity and heating due to either insect attack or excess moisture.
• The rice can safely be stored in warehouses without reduction in quality and quantity of rice.
• If the warehouses are not aerated or damp-proof, the free fatty acid rises from initial 35 to 320.
• The rice becomes unacceptable when acid reaches 350 unless it is remilled.

Brokens

• Broken's are of two types - big broken's are generally over 1/4 the size of the kernel and small broken's are less than 1/4th.
• These are graded and filled in separate jute bags.
• The normal storage period for broken's is 2 to 6 months because they develop rancidity very soon.

Bran

• Bran can be stored for short period because it develops rancidity very fast.
• It is always better to dispose it off within a week's time after it is obtained from mill .

Grain Storage

• The key to good storage is hygiene and grain moisture contents.
• The target moisture for storage is less than 14%.
• The following table shows the storage possibilities and problems associated with difference grain moisture contents.

Grain moisture content (%)	Safe Storage	Possible Problems
> 40		Germination
18	2 weeks	Fungal growth
> 14
12 - 14	1 year >
> 8		Insect damage
8 - 10	> 1 year

• Calculation of moisture content
• Moisture content can be on a wet (MC wet) or dry (MC dry) basis:
  • MC wet = Weight of moisture in wet grain * 100/(weight of wet grain)
  • MC dry = Weight of moisture in wet grain * 100/(weight of dry grain)
• Grain moisture depends upon the temperature and the relative humidity of the air.

The following table shows this relationship.

Hygiene for storage

• Keep storage areas , crevices, wooden pallets etc clean by spraying with the recommended insecticide to disinfect insect breeding places.
• Place sticky traps in the drying and storage areas for rats.
• Storage rooms should be physically rodent and bird proof, if possible.
• If necessary, treat storage sacks with insecticide to prevent insect infestation.
• This however is a dangerous practice if there is a chance that the seeds will be milled for consumption, and therefore is not recommended.
• Inspect the stored seeds once a week for signs of insect infestation.
• If there is infestation, under the direction of a trained pest control technician, the storage room or the seed stock may be enclosed hermetically with tarpaulin and fumigants.
• Phostoxin is used by the grain milling industry.
• This will kill all insects, larvae, and rodents in the enclosure.
• For long term seed storage, store the seeds in bags in storerooms with controlled temperature and relative humidity.
• The recommended storage environment for rice seeds are less than 20 °C and 40% R.H.
• In this conditions both fungi and insects will be inhibited.
• The difference constituents of rice undergoing storage are:
  1. Paddy,
  2. Milled-raw rice,
  3. Milled-boiled rice,
  4. Bran,
  5. Brokens

• Paddy is stored either on the farms or in the rice mills.
• Rice undergoes storage at the mills and in commercial warehouses.
• Bran, brokens and germs are stored only in the mills from where these are sold and for end use.
• Paddy : A sizeable quantity of paddy is held on the farms either as seed, or for hand-pounding or for milling and consumption, as required, paddy harvested in October-December is mostly retained on the farms.
• Summer and autumn crop paddy is not held on the farms, because of drying problem and susceptibility to discoloration.
• Storage in farms : On the farm, paddy is stored indoors in jute bags or in containers made of rope (morai), straw (Bharola), bamboo (Kanagi) or mud (Kuthla or Kuthi).
• When quantities held in storage exceed a tone, the containers made of rope, straw or bamboo are used and these are placed out doors.
• The outdoor containers are covered with a sloping straw roof.
• Capacity of the out door containers ranges between 1.5 and 10 tones.
• To avoid storage losses, use of either cement or steel bins are recommended.
• Storage in mills : In the mills, paddy is placed in chambers or in the open either loose or in jute bags.
• The period of storage in the mills ranges between 2 and 8 months.
• Paddy kept in the chambers without adequate protection from pests and moisture sustain a loss both in quantity and quality.
• In the open, weather conditions cause either sprouting or discolouration. Birds, rats, monkeys, squirrels, and insects attack paddy kept in the open and cause quantitative losses and also contaminate the grain with undesirable substances.
• Storage in Ware houses Paddy stored in warehouses which are damp and rodent-proof, suffered a loss only on account of reduction in moisture content.
• In these warehouses, paddy filled in jute bags is placed in standard-sized lots of 6x10x6 m.
• For keeping paddy in the open, land that is not susceptible to flooding is selected and is paved either with bitumen or with bricks.
• Paddy filled in jute bags is then placed in lots of 6 (breadth) x 10 (length) x 7 (height) m after arranging either wooden pellets or concrete blocks on the ground that provide for an air-gap of 15 cm between the floor and the bag.
• The lots are then covered with polythene to protect the grain from weather and pests.
• The loss in this storage is observed to be only quantitative and brought about by reduction in moisture content.
• It has been possible to hold large quantities of paddy free of spoilage for a year in this type of plastic storage which does not have a conventional roof over it and is exposed to the weather.
• Storage in silos : Silos have been used for storage of paddy in India during the last few years.
• These are either steel or concrete circular silos, capacity ranging between 350-600 metric tones (for wheat this capacity is 500-850 metric tones).
• Initially, flat bottom silos were used with provision of screw conveyors at the bottom to take paddy out.
• Unloading of paddy from flat bottom silos was found slow and labourious.
• Only hopper bottom silos are now in use for paddy storage.
• The silos storage unless adequately understood and properly supervised results in discolouration and spoilage of paddy.
• The funnelling, takes place while unloading operations are in progress, leaves some paddy undistrubed on the sides of the silos.
• Special arrangements are necessary to effect a turn-over for the paddy that remains on the sides of the silo.
• In a silo, paddy can be stored in the same condition and without any loss in quantity.
• It is also possible to adjust the condition of paddy at the time of delivery with the result that maximum out-return of rice can be obtained from such paddy in the course of milling.

Cost details of different storage methods

Item	Conventional warehouse (storage in jute bags)	Silo (Concrete)(Storage in loose)	Plastic storage with concrete flooring (storage in jute bags)
1. Initial construction	230.0	350.0	25.0
2. Interest depreciation and maintenance	21.0	33.0	10.0
3. Storage charges per tonne per year (including loading in and out charges)	33.71	14.35	32.71
Total storage cost (2)+(3)	54.71	47.35	42.71

Rice

• There is no alternative at present to storage of rice in jute bags.
• Bulk storage of rice has not been possible so far because of deleterious effects of mechanical pressure.
• Unpolished or brown rice can be stored for short periods provided the bran layer is intact.
• The rice moved and/or a stored in India :
  • Semi-polished (4 to 5 per cent removal of bran) or
  • polished (10-12 per cent removal of bran).
• Traditionally, consumers prefer raw rice that has undergone storage over a year.
• In case of boiled rice, the preference is for fresh milled rice.
• In storage, rice tends to develop rancidity and heating as a result of either insect attack or excess moisture.
• Presently, sizeable quantities of semi-polished raw and boiled rice are held in buffer storage for periods varying between 4 and 20 months.
• It is noticed that with standard storage practices (IS 6151-I-71) in warehouses that are well-aerated and damp proof as well as rodent-proof, when the stack size is 10 m x 6 m and height is 16 bags, and when initial moisture is not in excess of 14 per cent and insecticidal treatments are carried out in time, the only loss to rice in storage is that brought about by reduction in moisture content.
• When storage is done in warehouses that are neither aerated nor damp-proof, in storage of 6 months, free fatty acidity rises from initial 35 to 320.
• Rice becomes almost unacceptable when it reaches 350, unless it is re-milled.
• Rice that is polished is less susceptible to development of rancidity on storage up to two years.

Brokens

• Brokens are graded either as big or small.
• Big brokens generally are over 1/4th the size of the kernel and small brokens less than 1/4th .
• All brokens are packed in jute bags and the filling ranges between 75 and 90 Kg.
• Brokens, particularly small brokens develop rancidity very soon.
• The normal storage period is 2-6 months.
• Insects are mainly responsible for causing deterioration in storage.
• Spoilage, is heavy, wherever bird and rodent damage exists, causes sizeable quantitative loss.
• The demand for brokens being good, the aim generally is to dispose of these as quickly as possible.
• When the demand slows down, however, alternative uses for brokens will need attention and then production of clean brokens and grading them to set standards would assume significance.
• There is a greater danger in brokens of quantititive and qualitative loss, due to insects, rodents and birds, as compared with rice.

Bran

• Bran is filled in jute bags of 60-70 kg capacity.
• Bran obtained from huller mills is cleaned and disposed off in week's time as cattle/poultry feed.
• Bran from disc huskers and rubber-roll shellers is used mainly for oil-extraction and subsequently is either exported or used as cattle feed.
• Bran is not kept in storage for long because of rapid development of rancidity

Factors affecting storage

• Several factors that influence the storage of food grains are moisture content, quality of produce, climate, storage conditions.
• The most important factors deciding the storability of the produce is moisture content of grains. High moisture content of grains results in severe attack of insects and microorganisms in addition to heating and germination.
• Moisture content of paddy for safe storage:
  • Paddy , Raw Rice 14%
  • Parboiled Rice 15%
• Among the climatic factors
  • Temperature
  • Light
  • R.H. ,are important factors influencing storage of food grains.

Temperature

• Respiration of grains increases with increase in temperature.
• In addition temperature influences the metabolism, growth, development, reproduction behaviour and distribution of insects.
• Insect development is generally limited below 10 °C and above 45 °C.

Light

• Light influences movement and development of stored grain pests.
• In case of rice storage insects show photo negative response.
• Darkness is necessary for egg laying.

Relative humidity

• Under high R.H. moisture content of grains increases.
• Tropical climate, in which temp and R.H. are high, are favourable for the growth and multiplication of insects.
• Because of favourable conditions throughout the year, pest problem is continuous and high in tropical regions compared to temperate regions.

Storage practices in India

• The storage function is as old as man himself, and is performed at all levels in the trade. Producers hold a part of their out put on the farm .
• Traders store it to take price advantage.
• Processing plants hold a reserve stock of their raw materials to run their plants on a continuous basis.
• Retailers store various commodities to satisfy the consumers day-to-day needs.
• Consumers, too, store food grains, depending on their financial status.

The storage of agricultural products is necessary for the following reasons:

• Agricultural products are seasonally produced, but are required for consumption throughout the year.
• The storage of goods, therefore, from the time of production to the time of consumption, ensures a continuous flow of goods in the market.
• Storage protects the quality of perishable and semi-perishable products from deterioration.
• Some of the goods, e.g., woollen garments, have a seasonal demand.
• To cope with this demand, production on a continuous basis and storage become necessary.
• It helps in the stabilization of prices by adjusting demand and supply.
• Storage is necessary for some period for the performance of other marketing functions.
• For example, the produce has to be stored till arrangements for its transportation are made, or during the process of buying and selling, or the weighment of the produce after sale, and during its processing by the processor.
• The storage of some farm commodities is necessary either for their ripening (e.g., banana, mango, etc.) or for improvement in their quality (e.g., rice, pickles, cheese, tobacco, etc.), and storage provides employment and income through price advantages.
• For example, middlemen store food grains by purchasing them at low prices in the peak season and sell them in the other seasons when prices are higher.

Risks in Storage:

The storage of agricultural commodities involves three major types of risks. These are as follows:

• Quantity Loss
• The risks of loss in quantity may arise during storage as a result of the presence of rodents, insects and pests, theft, fire, etc.
• Dehydration too, brings about an unavoidable loss in weight.
• It had been estimated that about 10 million tonnes of food grains are lost every year because of poor and faulty storage.
• Quality Deterioration
• The second important risk involved in the storage of farm products is the deterioration in quality, which reduces the value of the stored products.
• These losses may arise as a result of attack by insects and pests, the presence of excessive moisture and temperature, or as a result of chemical reaction during the period of storage
• Dehydration of fruits, vegetables and meat during storage may lower their sale value.
• Butter , if not properly stored, may become rancid, which reduces its sale value.
• The loss in the quality of farm products varies with their quality at the time of storage the method of storage and the period of storage.

Price risk in storage

• This, too, is a important risk involved in the storage of farm products.
• Prices do not always rise enough during the storage period to cover the storage costs.
• At times they fall steeply, involving the owner in a substantial loss, Farmers and traders generally store their products in anticipation of price rise and they suffer when prices fall.

Storage Structures

Storage structures of farm products are of two basic types, depending on whether they are; Stored underground or Above the ground. There is no intrinsic difference between these two provided that basic requirements of safe storage are met. The advantages and disadvantages of these two types of storage structures are given as follows:

Underground Storage Structures

• Underground storage structures are dug-out structures similar to a well with sides plastered with cowdung.
• They may also be lined with stones or sand and cement. They may be circular or rectangular in shape.
• The capacity varies with the size of the structure. These structures are known by difference local names in various regions.
• In Rajasthan the under ground storage structures for food grains are known as 'Khai'.

The advantages of underground storage structures are:

• Foodgrains in an underground storage structure are more free from the seasonal variations in temperature and humidity provided that adequate precautions are taken against the seepage of water in the structures, especially in areas where the water table is high.
• Underground storage structures are safer from threats from various external sources of damage, such as theft, rain or wind. However, they are not good when the quantity available for storage is small, and there are a number of varieties to store.
• The underground storage space can temporarily be utilized for some other purposes with minor adjustments; and
• The underground storage structures are easier to fill up owing to the factor of gravity.
• However, it becomes cumbersome to take out the grains from these structures.

The advantages of Surface storage structure

• They can be maintained in more hygienic conditions by cleaning or white washing them;
• They are more convenient for inspection and the performance of various operations during storage, such as spraying and dusting, fumigation and turning of the grains; and the danger of heating up of grain due to internal heat is less.

Limitations of surface storage structures

• However, the cost of storage in terms of the maintenance of storage structure, handling costs, and losses due to external factors are higher in surface structures.
• Vertical silos on the ground are often constructed for storage; but these have a limited application because of their cost and the requirements of energy for their operation.
• The losses are low; but the absence of bulk transport facilities, and the use of traditional handling and marketing methods make them unsuitable in larger numbers.
• Their utility for storage is at the ports for the export/import of food grains.
• The food corporation of India has undertaken the construction of vertical silos (on the ground) at a few places.
• Food grains in a ground surface structure can be stored in two ways
• Bag storage or
• Bulk storage.

Bag storage

Farm products are stored after placing them in gunny bags made of jute. Storage in bags has following advantages each bag contains a definite quantity which can be bought, sold or dispatched without difficulty; bags are easier to load or unload.

• The bags which are identified as infested on inspection can be removed and treated easily; and the problem of the sweating of grains does not arise because the surface of the bag is exposed to the atmosphere.

Bulk or Loose Storage

Farm products are sometimes stored in surface structures in a loose form,. The advantages of this method are: The exposed peripheral surface area per unit weight of grain is less. Consequently, the danger of damage from external sources is reduced; and pest infestation is less because of almost airtight conditions in the deeper layers. These two points in favour of bulk storage are significant.

• The only precaution necessary for bulk storage is to avoid the sweating of grains.
• Kothi or Mud Pots: These are cylindrical in and are made up of unburnt clay mixture with straw and cowdung or cowdung, mud and bricks. The capacity of these varies from one to 50 tonnes.
• Kuthla: These are cylindrical bins of mud/brick mixed with straw and cowdung.
• Thekka: These are rectangular in shape and are made up of gunny or cotton wound around wooden support.
• Metal Drums: These are cylindrical in shape and are made up of iron sheets.
• Gunny Bags:These bags are made up of jute and are used for storing food grains and oil seeds.
• Essentials of a good foodgrains storage Structure Foodgrain storage structures must have the following specific characteristics:
• There must be enough strength in the walls and floor to support the weight of the grain to be stored the structure should be inaccessible to insects, birds, rodents, unauthorised persons and moisture to save quality and quantity losses.
• The structure should be free from excess heat or rapid changes in temperature; and
• The structure must provide for the easy entry and removal of the grain as well as for the application of insecticides and pesticides, if there is any need for them.
• Improved grain storages structures .Keeping these points in view, various institutes engaged in research have envolved storage structures for farm as well as for large-scale storage.
• These improved grain storage structures are as follows.
• For small scale storage;
• PAU bin: This is a galvanized metal iron structure designed by the Punjab agricultural University, Ludhiana. Its capacity ranges from 1.5 to 15 quintals.
• Pussa bin: This is a storage structure designed by the Indian Agricultural Research Institute (IARI), New Delhi, and is made of mud or bricks with a polythene film embedded within the walls.
• Hapur Tekka: This is a storage structured designed by the Indian Grain Storage Institute, Hapur.
• It is a cylindrical rubberised cloth structure supported by bamboo poles on a metal tube base, and has a small hole in the bottom through which grain can be removed.
• For Large Scale Storage:
• CAP Storage (Cover and Plinth): This has been developed by the Food Corporation of India. It involves the construction of brick pillars to a height of 14" from the ground with grooves into which wooden crates are fixed and embedded with a polythene sheet.
• The structure can be fabricated in less than 3 weeks.
• It is an economical way of storage on a large scale.
• Warehouse: Warehouse facilities in several areas have been created by the Food Corporation of India, the Central Warehousing Corporation, the State Warehousing corporations and Co-operative Marketing Organizations.
• These are scientific storage structures constructed on a large scale.
• Silos: The Food Corporation of India has constructed a few scientific silos for storage of food grains in main surplus producing area like Punjab.
• In these structures, the grains in bulk are unloaded on the conveyor belts and, through mechanical operations, are carried to the storage structure.
• The storage capacity of each of these silos is around 25,000 tonnes.
• However, these are reported to be not being fully and regularly used due to operational problems.
• Costs and Returns on Storage The gross return on storage may be defined as the increase in the price of the stored product at the time of storage till it is "de-stored" and either sold or consumed.
• The cost of storage should include the following:
• The cost of the maintenance of the storage structure, i.e., depreciation, repairs, insurance and interest on sunk capital; or alternatively, the rent paid for hiring the storage structure.
• Interest on the value of the stored goods;
• Value of the quantitative and qualitative loss during storage;
• Risk premium for a possible price fall and damage during storage;
• The cost of protective material; for example; insecticides, pesticides, rodenticides, fumigation, gunny bags , electricity, polythene covers; and
• Tax payments, payments to labour, etc.,
• These items of costs may be grouped into fixed or variable costs, depending on whether they vary with the quantity of goods stored or not. For example, for a professional warehouse owner, the maintenance and repair of the storage structure, the salaries of the permanent staff, depreciation of the building, taxes, record keeping, etc., are fixed costs.
• For a farmer, however, who is trying to decide whether to sell or store the grains for some time for later sale, all the costs are variable.
• Whether it pays a farmer to store his farm produce may be worked out with the help of the following formula NR = GR - C Where NR = Net returns to storage GR = P1-P0 P0 = Purchase price or market price at the time of storage.
  • P1 = Selling or market price at the time of de-storing C = Cost involved in storage NR > 0, implies positive returns on storage NR < 0, indicated negative returns on storage.
• The percentage margin (MS) from storage may be calculated as:
  • MS = (P1-P0-C)/(Pq+100) *100

Items	Rs.
Charges of loading at the auction platform and unloading in the warehouse	4.00
Transportation charges from the auction platform to the warehouse	5.00
Warehouse charges for 9 months	45.00
Loss during storage and transit	5.00
Interest on Rs. 500 foregone for 9 months @ 16% per year	60.00
Transportation charges from warehouse to the auction platform	5.00
Loading at the warehouse and unloading at the auction platform	4.00
Total:	Rs. 128.00

• Using the notions given earlier, P0 = 500, C=128, NR will be positive only if P1, pr price of wheat in the month of December is expected to be more that the sum of P0 and C i.e., Rs. 628.00.
• Cost Benefit Ratios of Various storage practices of paddy Cost of storage varied among difference storage methods.
• To show this the costs of storage per month of paddy were computed.
• At the farmer's level the cost of storage comprise the interest on initial investment (fixed capital), depreciation on establishment, repairs and maintenance charges, insurance and taxes, interest on the value of the stored goods, value of quantitative losses during storage, labour charge for loading and unloading of grain, treating and conditioning cost and transport charges.
• Economics of storage in Puri of one quintal capacity.
• Initial cost of storage structures (Puri of one q capacity) (Rs/q) = Rs. 2.54 Initial cost of one quintal of paddy = Rs.480.93
  

Storage Charges

• Treating and conditioning cost = Rs.5.38
• Interest on initial investment at the rate of 12.5 per cent = Rs.0.43.
• Interest on the value of the stored grain at the rate of 10 per cent of the value = Rs.48.09
• Value of the quantitative losses during storage = Rs. 4.98.
• Storage charges / quintal - Rs. 58.89
• Cost of paddy + storage charges/q = Rs. 539.60
• Selling price of the grain/q = Rs.549.60
• Net return per quintal of paddy = Rs. 9.78
• Per centage margin from storage = 0.019.
• No depreciation was charged on the Puri because it is constructed every year.
• Economics of Storage in Gade of one Quintal Capacity.
• Initial cost of storage structures (Rs/q) = Rs.29.54
• Initial cost of one quintal of paddy = Rs.445.33.

Storage charges

• Treating and conditioning cost = Rs.3.50
• Interest on initial investment at the rate of 12.5 per cent = Rs.3.69
• Depreciation on storage structure/q = Rs.2.81(useful life taken as 10 years)
• Repairs and maintenance cost/q=2.74
• Interest on the value of the stored paddy at the rate of 10 per cent = Rs.44.53.
• Value of the quantitative losses during storage = Rs.39.69.
• Storage charges/quintal = Rs.92.98
• Cost of paddy/q + storage charges/q = Rs.538.31
• Selling price after storage/q = Rs.550.00
• Net return per quintal of paddy = Rs.11.69
• Per centage margin from storage = 0.022
• Economics of Room Storage of one Quintal Capacity (Rs/Q)
• Initial cost of storage structures (Rs/q) = Rs.44.44
• Initial cost of one quintal of paddy = Rs.415.78.

Storage Charges

• Interest on initial investment @ 12.5 per cent = Rs. 5.55
• Depreciation on storage structure/q = Rs.1.75
• Repairs and maintenance = Rs. 1.59
• Insurance and taxes = Rs.2.00
• Interest on the value of stored food grains @ 10% = Rs.41.58
• Value of the quantitative loss during storage Rs. 39.36.
• Labour charges for loading and unloading = Rs.3.50
• Storage charges/quintal = Rs.95.34
• Cost of paddy/q + storage charges/q = Rs. 511.13
• Selling price after storage = Rs. 78.82
• Net return from storage = Rs.17.59
• Per centage margin from storage = 0.034.
• Paddy costs and benefits of various storage practices

Methods of Storage	Cost of Storage per quintal for no of months of storage	Cost of storage per quintal for one month of storage	Gross returns per quintal for no. of months of storage	Gross returns/q for one month of storage	Cost benefit ratio for one quintal for one month storage
Puri(Made with paddy straw)	58.89(7)	8.41	68.67(7)	9.812	1:1.166
Gade (made with bamboo strips)	92.98(7)	10.33	104.67(9)	11.630	1:1.125
Rooms	95.34(8.5)	11.21	112.93(8.5)	17.374	1:1.184

Pests And Controls

The stored grains are chiefly subjected to attack of insects, rats and micro-organisms. The insects feed on grains causing heating and deterioration in stored produce. Rats cause considerable damage and spoil the grain more than their need by way of food contamination. Micro-organisms like fungi, bacteria etc., are responsible for maximum spoilage of food grains in storage and bring about heating, off odour, discoloration, loss of nutritive value and change of palatability.

• Most of the stored grain insect pests have a high rate of multiplication and within one season they may destroy 10 - 15 % of the grain and contaminate the rest with undesirable odours and flavours.

The following are the insect pests to cause damage the rice during storage:

Insect Pest and Damages

Rice weevil (Sitophilus oryzae Linn)

• Both the grubs and adults bore into the grain and feed inside.
• Lesser grain borer (Rhizopertha dominica fabr)
• The grubs and adults cause serious damage by feeding inside the grain.
• It is a pest of unhusked paddy.

Khapra beetle( Trogoderma granarium everds)

• The grub eats the grain near the embryo or another weak point and from there it proceeds inwards.

Rice moth (Corcyra cephalonica stain)

• It is primarily pest of rice.
• The larva(caterpillar) damage the grains of rice by feeding under silken webs.
• In case of severe infestation the entire stock of grain may be converted into a webbed mass and ultimately a characteristic bad smell develops resulting in grains unfit for human consumption.

Angoumos grain moth (Sitotroga cerealella oliver)

• The larva (caterpillar) feed on internal content of grain and pupates inside of the grain.
• It inflicts severe damage to unhusked paddy.

Preventive Measures

• Dry the grain properly before storing.
• Store grain in receptacles or godowns.
• Disinfect old gunny bags by dipping then into 0.1 % Malathion 50 EC suspension (2 ml/lit of water) for 10 min and drying them in shade before filling with grains.
• Disinfect empty godowns by spraying 0.5 % Malathion suspension (10 ml/lit of water) on floors, walls and ceilings.
• Alternatively disinfectant godowns either with 25 tablets Aluminum phosphide or 35 lit of EDCT mixture for 1000 m3, empty space before storing grain.
• Mix Malathion 5 % dust @ 2.5 kg/ton i.e.,2.5 gm/kg of grain meant for seed purpose.
• In the stores the paddy bags should be stacked on elevated structures (dunnage) to avoid direct contact of bags with the floor and for providing aeration.
• Care to be taken that the bag should not touch the walls to prevent the absorption of moisture and also hiding place for rats.

Curative Measures

• Fumigate the infected products with aluminum phosphide tablets @ 1 tablet / metric ton or 25 tablets for 1000 m3 space with exposure period of 7 days.
• Alternatively EDCT mixture @ 1 lit for 2 metric tons of grain or 35 lit / 100 cubic Mts. space with exposure period of 4 days.
• For small scale fumigation use EDB @ 3 ml/quintal of grain with exposure period of 4 days.

Precautions To Be Taken While Fumigation

• The fumigant should be used only in air tight stores or under tarpaulin in the open by specially trained persons, because the fumigants are deadly poisonous.
• Aluminum phosphide should not be used in living quarters.
• Grain stored in metal bins may also get infested if not treated with malathion.
• They should also be fumigated.
• Do not mix DDT/BHC dust even with the seed intended for sowing.
• Storage fungi primarily Aspergillus and Pencillium spp occur almost universally and attack seed stored at relative humidity of 65 - 100 %.
• When seed moisture content or atmospheric relative humidity is high, storage fungi grow rapidly and may damage seed and may cause heating.
• To prevent fungal diseases seed with less than 14 % moisture content should be stored in air tight godowns.

Control Of Rats During Storage Of Grain

• Avoid thrash and unwanted materials near about the storage structures.
• Fix Zinc sheets at the bottom of the wooden doors to prevent the entry of rats into the godowns.
• Block all drainage holes with wire mesh and once the rats enter into the godown, they should be controlled by rat traps.
• Organize periodical baiting with Zinc phosphide or Warfarin.

Status of storage pests

• Pest control is aided by block stacking, adequate aeration and maintenance of good hygiene.
• Pesticides are used for protective and control treatments.
• For protective treatments against insects, either malathion, DDVP or pyrethrum are used for control.
• Fumigation is carried out with either aluminium phosphide ethylene dibromide or methyl bromide.
• Anti-coagulants are used against rodents.

The recommended pesticide schedule for storage pests is given below:

Name of the Pest	Paddy	Milled Raw rice	Milled Boiled Rice	Brokens	Bran
INSECTS
Rhyzopertha dominica Fab	*	+	0	+	0
Sitophilus oryzae Linn	+	*	+	*	0
Trogoderma granarium EV	0	*	*	*	0
Sitotraga cerealella Oliv	*	0	0	0	0
Corcyra cephalonica St	0	*	0	*	*
Cadra cautella Walker	0	*	0	*	*
Plodia interpunctella Hub	0	+	0	+	+
Tribolium castaneum Herb	0	+	+	*	*
Latheticus oryzae wat	0	+	*	*	*
Oryzaephilus surinamensis Linn	0	*	*	*	*
Oryzaephilus surinamensis Linn	0	*	*	*	*
Alphitobius piceus Oliv	0	0	0	*	*
RODENTS
Rattus Rattus Linn	*	*	+	*	*
`Rattus norvegicus Berk	+	+	+	*	*
Mus musculus Linn	+	*	+	*	*
BIRDS
Sparrows	*	*	+	*	0
Pigeons	*	*	+	*	0
Crows	*	0	0	0	0

Note: O - insignificant+ - minor* - major

• Malathion - 50 per cent E.C. Premium grade.
• Used as a spray (dilution 1:100 and 3 litres of dilute material for every 100 m2) for protection of all rice products once in 15-20 days.
• Pyrethrum - 2.5 per cent Pyrethrum, E.C. used as a spray (dilution same a Malathion) for protection of all rice products, once or twice a week, as required.
• DDVP - 100 per cent E.c. used as a spray (dilution 1:300 and 3 litres for every 100 m2) for control of surface and winged infestation.
• Aluminium phosphide - Solid tablets of 3g each. Used as a fumigant for control of infestation, in all rice products.
• Dosage - 6 g/tonne under airtight covers and 43 g/m3 for sheds with an exposure period of one week.
• Ethylene dibromide - Liquid.
• Used as a fumigant only for rice and brokens when control of infestation is necessary.
• Only used for shed fumigation at the rate of 22 g/m3 with an exposure of one week.
• Methyl bromide - Liquid. Used as a fumigant only for rice and brokens when control of infestation is necessary.
• Only used for shed fumigation at the rate of 22 g/m3 with an exposure of 48 hours.
• Warfarin - This is an anti-coagulant used for rat control.
• It is used at 5 per cent level with any attractive edible material.
• About 10-15 days continuous baiting is necessary to wipe out the rat population.
• Where mice are present the period may have to be extended to 20 days.
• It is necessary that pest control measures are used by trained operators.
• Full attention has to be paid to precautionary measures including use of antidotes.
• Mixing of pesticides with food grains is not advisable in view of the consequent hazards.
• Residue tolerance for the above pesticides as far as rice and other products are concerned has been fixed under the Pure Food Act of Government of India.
• The treatments have to ensure that these residue limits are not exceeded.
• Pest control agencies undertake control work under expert supervision and ensure meeting relevant requirements.