Harvesting

• The most difficult and time-consuming operation in the growing of castor was for many years that of harvesting.
• When the crop was grown on a peasant scale with all operations manual, this was of little importance.
• There was frequently no competition from other crops with high labour demands, since castor was usually grown in areas unsuitable for other crops with high labour demands, since castor was usually grown in areas unsuitable for other cash crops, or their harvesting was completed before the castor matured.
• When grown as an intercrop or on odd scattered patches, the labour required for harvest was small, and could be carried out at the owner's convenience.
• Growing interest and increasing world demand for castor oil encouraged large-scale plantings.
• These were often of local giant types, and it was soon apparent that economic production with adequate returns to growers except by planting the more resistant local types.
• The second could be so influenced, and the selection followed by breeding the dwarf types suitable for fully mechanized types, machinery was developed which either stripped off the capsules for later hulling, or combined both operations in one machine.

• The price realized for such seed was low, for the quality was often poor, and leaving hulled seeds in the hot sun reduced their oil content.
• The search for alternative cash crops in many tropical countries resulted in the increased planting of castor, sometimes on a fairly large scale.
• It quickly became obvious that harvesting and hulling of the crop was the major problem to be solved, since many of the indigenous and giant types planted showed considerable resistance to insect attack.
• Where labour was available, harvesting and hulling could be carried out on traditional lines, the operation then becoming a full-time occupation during the period.
• But where labour was short, some form of mechanical harvesting or hulling was essential.
• Similar methods of reducing labour and speeding these operations have been developed in many regions of the world.
• The clusters are usually stripped by hand, the unshelled seed being taken to a central depot for hulling.
• Harvesting of the giant types, the clusters were often so high above the ground that it was necessary to climb the tree to pick them.
• Frequently, through idleness, a whole branch was slashed off irrespective of the proportion of ripe or unripe clusters.
• In both instances considerable damage to the plants occurred with a major reduction in potential yield.
• Long-handled harvesting shears and knives were introduced to cut off the whole cluster, and were very successful.
• Hand-reaping is carried out most efficiently by means of a reaping jug, or stripping cup.
• This is a metal container, shaped like a cone or large beer mug, 20-30 cm high and approximately 20 cm across the open end. Opposite the handle is a slot extending 10 cm from the mouth of the cone, tapering from 2.5 cm wide at the top to 1.25 cm at the bottom.
• The edges of the slot may be reinforced, if required. With a more hard-wearing metal plate.
• Reinforcing the edge of the slot allows the cup to be made from thinner material, and substantially reduces its weight.
• This is important where large areas have to be reaped, as workers become less tired.
• Clusters are reaped by guiding the base of the spike into the slot, and drawing the jug upwards so that the capsules fall into the jug.
• Seeds not mechanically hulled were shelled by spreading the capsules 15cm deep on a threshing floor in the sun.
• Within 5-6 days most of the capsules will have shattered.
• It is desirable to surround the area with corrugated iron sheets, as the seeds shoot out with some force when the hulls shatter.
• This hand-reaping system is used for harvesting dwarf castor with considerable success.
• Mature racemes are cut by hand and transported to central threshing areas in sacks or baskets.
• These threshing floors can be natural areas of hard soil or rock, or specially constructed of concrete or paving.
• Hulling is by beating with sticks after the capsules have been spread in the sun to become thoroughly dry.
• Small hullers have been obtained co-operatively in some districts, and operate at these threshing floors.
• Both large and small-scale plantings in Brazil are mainly hand-harvested, and the ripe clusters transported to a central hulling point.
• Clusters were stripped off plants using a heavy leather glove, or broken off complete.
• They were then drawn through the U notch cut in a steel plate fixed in the collecting basket.
• Capsules are sometimes hulled by rubbing on a corrugated rubbing board, but this is a time-consuming operation and is little practices.
• On the Indian continent where many of the indigenous cultivated varieties are not so tall as in other parts of the world, harvesting is consequently more simple.
• Harvesting operations are generally spread over a period of five to ten weeks, and between four to six pickings are necessary.
• Highest yields are obtained where the clusters are harvested at maturity, tied in bundles and hung to dry, but normal practice is to harvest the crop when a few fruits on each spike ripen.
• The many immature seeds harvested in the process reduce the quality and quantity of the crop.
• In southern India the harvested capsules are placed in heaps over which cow-during water is sprinkled to soften the husk and assist shelling.
• This local practice is based on a belief that this imparts a good colour and gloss to be seed.
• The treated heaps are covered with straw and weighted to exclude air.
• In northern India, capsules may be buried in pits and covered with dung and earth.
• This is considered to assist ripening of immature fruits and facilitate milling.
• After four to ten days the capsules are spread in the sun to dry.
• In China harvesting is by the traditional local method
• Clusters are snapped or cut off, tied in bundles on racks similar to those used for drying paddy, or stooked in pyramids in the field to dry and later threshed by hand.
• Clusters may be stripped using a metal or wooden plate with a V-notch fixed above a large wicker basket, or a plaited cup with U-shaped notch.
• Hulling is usually carried out by beating with flails or sticks, the mixture of seed and hulls being cleaned by wind-winnowing.

• By 1956 combine harvesters were being manufactured commercially.
• The harvesting operation consists of removing the seed capsules from standing plants by the use of low-frequency vibration induced in the plants.
• This is accomplished by use of a beater mechanism that strikes the plant stem directly under the lowest raceme.
• Capsules are then conveyed to a huller.
• The hulls are removed in a drum which rolls the hulls off the seed between two rubber surfaces having a differential motion.
• The hulls are separated from the seed by a cleaning device and blown out of the machine to the ground.
• The clean seed is then elevated into a storage bin mounted on the harvester.
• The harvesting of seed crops requires great care and special skill in operating combines.
• Where plots are small, hand-harvesting is to be preferred if at all possible.
• Hulling can be mechanical, but hullers should be run at slow speeds, feeding should be regular, and capsules should be quite dry.
• Hulled seeds should be sorted immediately to remove those with damaged testa, dried of surplus oil from broken seed, and dusted with an insecticide if required.

• This should be as far as is possible in large blocks, for the purchase of a machine to be used on scattered small plots of local cultivators, even where the total is greater than the minimum required, would not be economic.
• The loss of time travelling between work, and the general wear and tear resulting from using specialized and heavy equipment on often badly constructed and maintained roads, had frequently resulted in expensive machinery, rashly purchased, causing financial ruin to enthusiastic but inexperienced farmer co-operatives.
• A two-row machine is cover some 120-200 hectares per season, working at a rate of 0.75-1.0 hectares per hour.
• Four-row harvesters are available, but are not as popular as the two-row type.
• They are slower in working, and the volume of seed passing through the conveyors and hulling discs is such that, except under ideal conditions, breakdowns and stoppages are more numerous than with the smaller machines.
• The two-row machines are said by the manufacturers to operate most efficiently at approximately 5 k.p.h., harvesting at the rate 0.75-1.5 hectares per hour in castor fields that yield 3000 shelled seed per hectare .
• Operators also vary greatly in technical skill and ability to use harvesters to the best advantage, and this is more important with castor than many other crops, since damaged seeds are valueless.
• Header attachments can be obtained to harvest either dwarf-or normal internode castor plants, grown in 90-100 cm rows.
• The rate of working depends almost entirely on the operator, since it is necessary to adjust the setting for individual crops and frequently during the actual harvesting operation.
• Harvesting losses can be kept below 5 percent by correct machine adjustment and by employing a skilled operator, provided good crop and weather conditions exist.
• However due to the nature of the crop, harvesting losses can become excessive with careless and improper machine operation, particularly when the seed is dry.
• Whatever type of harvester is used, it is primarily designed to harvest ripe, dry capsules and mature seed before the plant becomes brittle.
• Too long delay at harvest will result in losses by shattering and fracture of stems and branches.
• Capsules must be dry to hull properly, and are then easily shaken from the plants.
• Moist capsules do not hull easily, and excessive seed damage can occur in such conditions.
• Hulls and trash are ejected from the rear of the machines, and some are fitted with spinners to ensure even distribution.
• These hulls are a useful fertilizer, and contain approximately 1-6 percent nitrogen, 0.1 percent phosphorous and 3.8 percent potassium, besides adding to the humic content of the soil.
• Whenever possible, commercial hybrid castor plantings should be harvested by a combined harvester-huller.

• The majority of the machines available are designed to harvest seed when the capsules and plant leaves are dry and the relative humidity below 45 percent.
• At harvest the plants may be still growing, and the later-flowering spikes may bear immature capsules.
• These green capsules must be dried, and the leaves removed before harvesting.
• This is often accomplished naturally by killing frosts, and seed is ready for harvesting some ten days after such frost.
• Where frosts do not occur or are too late, aerial application of chemical defoliants can be made ten to fifteen days before harvest.
• Dinitro (DNAP) 3 litres in 20 litres oil was originally recommended for a single application, or half this rate in two applications, the first two weeks, and the second one week, prior to harvesting.
• Where temperatures below 29 ⁰ C are expected PCP at the rate of 0.6-1.7 kg per hectare a.i. should be used instead of (DNAP).From aircraft, the suggested rate is 3 litres aerial Gramoxone in at least 60 litres water per hectare.
• This is preferably applied by fixed-wing aircraft, fitted with either 'Micronair' or fine jets, flying as low over the crop as possible.
• Alternatively a helicopter can be used, but is usually more expensive.
• When spraying bipyridyl herbicides, this should preferably be carried out in the evening.
• Diquat at 4.0 kg. a.i. per hectare applied when all capsules had turned brown was most efficient, and gave the minimum yield reduction .
• Aerial application of magnesium chlorate at 15 kg per hectare in 100-150 litres of water successfully defoliated plants.
• This chemical caused gradual death of plants following leaf-fall.
• The relatively slow defoliation of the leaves increased the flow of assimilates to the seeds, and resulted in increased seed weight and oil yield per hectare.
• Defoliation may also increase yields by allowing harvesting earlier than would normally be possible.

• On an average, castor produces 4-5 sequential order spikes which can conveniently be harvested in 3-4 pickings starting from 90-120 days at intervals of 25-30 days, Premature harvesting leads to reduced seed weight, oil content and germinability.
• Since shattering is not a problem in any of the currently recommended improved varieties and male parents of any specific order spikes harvesting can be delayed until all capsules in the spike are fully dried.
• Even though the locules open in some non-dehiscent types, the membrane covering the seeds remain intact and hence the seed does not fall out to the ground.
• However incase of VP-1 which is provide to be partial shattering, harvesting has to be done little early.
• In such cases harvesting the spike as soon as the colour of capsules changes from green to yellowish brown and few capsules start drying.
• Allow the harvested spikes remain in the sun for 3-7 days before they are threshed/seperated.
• Seeds may be seperated from capsules either manually or mechanically.

• Castor-seed is very hard and does not require much care during storage.
• No insect or fungus attacks the seeds. Under ordinary conditions of storage in jute (gunny)bags, the oil and the free fatty acid content of the seeds are not affected even after three years of storage.
• Usually, castor - seeds are not required to be stored in warehouses over long periods.
• Being an important industrial and export commodity, it is immediately crushed locally or exported.
• In warehouses, castor seed is stored in gunny bags.
• Sometimes, if the bags get wet due to high humidity or leakage of rain-water, the seeds become slightly mouldy but this dies not affect either the oil or the free fatty acid contents.
• With sun drying, the source of damage can be eliminated. It is recommended that castor seeds be dried to 7-8% moisture content before storing.
• At domestic or farm level, storage of large quantities of castor seed is not recommended as it occupies a considerable space
• Castor seed is also not recommended to be stored in open as both heat and sunlight damage the germination and reduce the oil content.
• Artificial low temperature storage also affects the viability.
• Castor seed stored at 5 to 7⁰C temperature for 6 months reduced the germination from 93 to 3%.
• During bagging the seeds, handling should be minimized. On large scale handling, wooden scoops, shovels and rubber conveyor belts are recommended.
• Seeds should be stored at dry place and cooler part of the house.