SEED PRODUCTION IN NEW ZEALAND

New Zealand Journal of Agriculture, Volume 84, Issue 1, 15 January 1952, Page 13

SEED PRODUCTION IN NEW ZEALAND

Seed Cleaning: Grasses and Clovers

By

P. R. BARRER,

Instructor in Agriculture, Department of

Agriculture, Christchurch

THE extent of the grass and clover seed industry in New Zealand d and its value not only to the export trade, but also to the home consumer were shown in the first article in the "Seed Production in New Zealand" series, which appeared in the March 1948 issue of the "Journal". When it is realised that Detween £1,500,000 and £2,000,000 worth of seed has been exported annually over the last 4 years, and that this is less than’ the quantity of seed used within New Zealand, it is obvious that an efficient seed-cleaning industry is essential not only for the reputation of New Zealand seed overseas, but also for the benefit of New Zealand pastures. The seed-cleaning machines in use in this country and which are responsible for the good results achieved are very largely of local invention and manufacture. IN the pre-mechanical age the flail was used to free grain and other seeds from their stalks and the wind to separate the chaff and light material from the seeds. The first crude threshing machines incorporated a series of mechanically operated flails, while the use of a rotary fan to provide an air blast led to the first seed-cleaning machine/ termed a winnower. In 1788 Andrew Meikle, Whiterock, East Lothian, England, patented his revolving drum, which worked inside a concave, and which combined m one machine the operations of the flail and the winnower. His machine did a lot its predecessors had not done; it combined a striking and a-rubbing action to free the seed from the stalk. It then separated the seed, chaff, and other small particles from the straw by an agitated screen, finally using air blasts to separate the chaff and other impurities from the seed. Thus was evolved the threshing machine—particularly suited for handling grains—which was (with modifications) until comparatively recent years often the only method used for cleaning grain and other seed. Today the cleaning which is associated with the threshing of the seed is regarded only as a preliminary treatment, the final cleaning or machine dressing being carried out in central stores in up-to-date seed-dressing plants. In New Zealand the grass and clover seed industry began with the collection of cocksfoot seed, which

was first recorded as being saved at Pigeon Bay in 1854. By 1865 huge orders for. the seed were coming forward. The method of harvesting adopted was to cut the cocksfoot with a sickle, dry the cut material on the stubble, and sledge or cart it to a suitable place for threshing by flail or other means. Eventually there was a demand for some mechanical method of cleaning the seed, and a Christchurch firm, which had made use of screens in chaff cutters to take out dust and small seeds, produced about 1886 a small machine combining a threshing drum and separating screens, which proved to be very suitable to the Akaroa cocksfoot growers. This small portable mill was intended for use on the farm, but it was not long before the firm developed much more elaborate machinery for the seed-dressing stores which now handle the bulk of seed cleaning in New Zealand. In the earlier part of the 20th century most New Zealand grass seeds were harvested from older pastures, which were in most cases mixed pastures with one species predominant. This being so, naturally there were many impurities in the undressed seed. - In August 1912 A. H. Cockayne, speaking at the iniOn conference of the Farmers’ Union in Wellington, The extremely impure nature of much of our local seed In the rough Ims led to a system of seed cleaning that is unexcelled in any part of the globe. Thus we- have the extremely peculiar and interesting position of undressed local seed being probably the dirtiest in the world, while dressed seed of the same lines is, without doubt, unequalled in any seed-producing country so far as freedom from extraneous seeds is concerned. In 1912 the methods of harvesting and threshing of grass and clover differed from the labour-saving methods employed today. The English type of threshing mill which was then m general use in New Zealand had not undergone any fundamental changes in design since the first half of the 19th century. It made quite a fair job of cleaning out niost of the impurities. Though the much more recent" header harvester employs the same fundamental principles m its operation, it combines into one readily manoeuvrable machine the functions of the reaper and the threshing mill, The combination with all its advantages has one drawback; a limit to the space available in which to incorporate the various parts. Thus the sample produced by the header harvester cannot be expected to be as pure as that produced ' by the much larger threshing mill. Against this the great majority of seed producing areas are sown today with seed production in mind, and usually only two species—one grass and one clover— sown in these areas, which

are harvested for seed early in their life. Thus though the header harvester has almost entirely replaced the threshing mill, the effect has been offset by the change in seed production methods. Consequently seed-cleaning plants still have a similar task to perform, the removal of weed seeds, other crop seeds, broken seeds, pieces of straw, and other rubbish from the field-dressed seed. Separation Principles and Devices In the separation of weed, grass, and clover seeds, dirt, chaff, straw, and other foreign matter, including broken seed, principles are used according to the impurities in the line. The varying characteristics of the ' seeds and foreign matter have been made use of in devising the methods for eliminating them. These main characteristics are size, shape, and specific gravity. The most generally useful device in seed-cleaning machinery is the riddle, which depends upon size and shape differences for its usefulness. The perforations in a series of riddles reveal a great variety of shapes and sizes suitable for separating many kinds of impurities. The main riddle types include round and oblong holes punched into sheet zinc, and wire mesh giving square and various oblong openings. Opening sizes range from the equivalent of the smallest seeds harvested to the largest, the range used in any particular plant depending on the types of seeds handled. Three prime motions used in the operation of riddles are to and fro, up and down, and crosswise. A combination of to and fro and crosswise will give > a rotary motion. Again the riddles may be run on eccentrics on a steel spindle, thus combining to and fro and up and down to give the seed a jumping motion. In the seed trade such a machine is known as a “jump machine”. In addition to the type of motion of riddles, they may also be run at different speeds and pitches. Another device making use of size and shapd is the cellular cylinder. This, too, may be obtained with a large variety of shapes, sizes, and angles of indentations or cells in the inner surface of the cylinder. Cellular cylinders are fitted at an angle to the horizontal. As the cylinder slowly rotates material is picked up in the cells, leaving behind in the bottom of the cylinder anything too large to fit into the cells. As the material is lifted upward by the cylinder that of greatest length falls out first and returns to the bottom. Shorter material is lifted higher and when it does fall it is caught in a suspended trough running the length of the cylinder. The position of this trough or tray can be adjusted to make a separation at an earlier or a later stage in the cycle of the cylinder. The material remaining in the bottom of the cylinder works along and is caught at the lower end, while that gathered

in the tray is taken away separately, Thus a cylinder will make separations with great accuracy in material of the same shape in cross-section but varying in length. Such a separation would be an impossibility over riddles. In using air currents in a dressing plant advantage is taken of variations in specific gravity, by which chaff, straw, and empty glumes may be separated from sound seed, and lighter seeds such as grasses may be separated from denser seeds such as clovers. The current of air formerly obtained by blast is now more usually develop-

ed by suction. The strength of the current can be adjusted according to the line of seed being cleaned. A modern machine-dressing plant consists of a number of different types of machines, linked up as required into one plant, so that any line of seed may be fed into the hopper and go automatically through as many processes as are necessary for thorough cleaning. Sometimes lines will have to S° through the same process twice, The separations made in a line of Italian ryegrass are shown in the illustrations on page 14.

The number of separations made in cleaning a line of seed will depend both on the kind of seed and its condition before machine dressing begins. The accompanying flow diagram, though not that of any particular machine nor giving the order in which the component parts may be used or the numbers of the parts, illustrates a link-up of elevators, blast, riddles, and cylinders, which are essential in most cleaning operations. The following is a description of the labelled parts:— A— Hopper for field-dressed seed, usually built with the top just above floor level and large enough to hold several sacks of seed. B—-Elevator to lift field-dressed seed to machine. C—Air suction to remove light chaffy material. ’ DTop or scalping riddle; the largest impurities in the line are retained on this riddle, the balance passing through it. Second riddle, with similar function to the top riddle, but separating impurities more nearly the size of the seed being cleaned. This riddle may be employed to remove the largest seed or to carry over the main run of seed and allow only the smallest seed to pass through with small impurities. Third riddle; the seed being cleaned, together with impurities of similar size, pass over this riddle, smaller impurities passing through it. G, H, and J—Spouts at which the separations made by riddles E, F, and D are collected. ( KSecond elevator, lifting riddled seed to cylinders. L— First cylinder, which separates material of shorter length than the seed being cleaned, lifting it into the cylinder tray. M —Discharge point for material separated in first cylinder. N—Second cylinder, which separates material of greater length than the seed being cleaned. The dressed seed is lifted into the cylinder tray while the separated material passes along the bottom of the cylinder. O — Discharge point for material separated in second cylinder. —Hopper into which machine-dressed seed is delivered. Q — Elevator lifting machine-dressed seed to bagger. — Bagger for machine-dressed seed.

i SEED-CLEANING . ' MACHINES

Subsidiary Separating Devices , There are a number of subsidiary separating devices which may be required to deal with special classes of seeds or to improve the purity of difficult lines of seed. The dossor is a machine used commonly in the cleaning of clover. It makes use of revolving velvet surfaces on which irregular, fiat, and broken seeds are carried up and round seeds roll down. Another less usual but effective device has been incorporated in a machine which is particularly useful as a final process in removing chipped and broken seed from clovers. Magnetism is used to effect separation, it being necessary to mix . a very small quantity of iron filings with the clover, the filings adhering to the broken surfaces but not to the whole seeds. Still another machine, by using - wind and differing specific gravities of seed, is often able to separate seed of similar size but different weight with which riddles and cylinders may not be able to deal. In this machine, known as a specific gravity separator, a current of air passing upward ‘ through a perforated jumping table keeps the seed continually in motion and makes a number of very fine separations based on variations in the specific gravity of the material being handled. Saddlers’ felt or similar blanket material is sometimes used to separate “clinging” from other types of seeds. The material is suspended on a horizontal plane above the riddles of a jump machine. The action of this machine throws the seed against the under side of the material. Seeds such as sweet vernal adhere to the matted surface, while other seeds fall back to the riddle. The blankets require cleaning periodically if they are to retain their effectiveness.

The hummeller is used to remove husks from seed or . grain and to clip the long ends off oats. It is fitted with cutting knives or brushes according 'to the work to be done. At the outlet an air suction draws away all light material rubbed off by the hummeller. Brushes may also be used as other adjuncts to the seed-cleaning process. They may be used underneath the riddles or screens to prevent them becoming blocked with seed, so that uniform work may be ensured throughout the cleaning operation. For the shelling of some seeds such as Yorkshire fog, the brushes separate the shells from the kernels, the cylinders lift the kernels away, and an aspirator removes the husks by suction. Again, brushes may be used for . breaking up double heads of cocksfoot as well as for brushing up a sample to make it flow better when it is being sown, or they may be used in breaking up soft dirt in subterranean clover seed so that the dirt may then be removed. Polishers make use of brushes working over a wire concave. They are used by . seed-dressing firms to break

up small particles of dirt in clover, particularly white clover. Suction draws off the light material rubbed off by the polisher. The polisher may also be used to decrease the percentage of hard seeds in 'clovers. A “bounce” machine uses the resilience exhibited by sound pea seeds to separate them from damaged seeds and from pieces of dirt, of similar size. The material to be cleaned is bounced on to a series of plateglass surfaces which are set to allow a separation according to the resilience of the material. ' An electronic “eye” is used to make a separation according to seed colour. Thus discoloured and weathered peas can be separated from sound peas, and yellow seeds of linseed from brown seeds. Each seed comes individually under the “eye” and is graded according to colour. A Christchurch firm which has specialised in the production of seedcleaning machinery from early days supplies not only most of the New Zealand market, but exports seed-clean-ing machinery to Australia, Scotland, and Ireland. Improvements continue to be made not only in the design of existing machinery, but also by the invention of new devices, as for instance a recent patent for the removal of flat from round seeds in the dressing of clovers and brassicas. Seed-store Procedure

Individual stores have their own methods and techniques, but there are

certain general practices carried out in all stores. To understand the seedstore procedure it is necessary to follow a line of seed through the store from the time it enters to the time it leaves. All seed coming into store is first weighed in the wagon or truck on a weigh bridge, the tare weight of the conveyance being deducted to give the weight of the bags and contents, or the gross inward weight. The net inward weight of the seed is that obtained by deducting the weight of sacks from the gross inward weight. As the

wagon is unloaded and a tally made of the number of sacks every bag is sampled to see that all sacks are similar in their contents. The line is then stacked to await its turn for machine dressing. Various methods may be used in stacking, but nearly all firms now use an electric hoist. Should the line be one with a marked variation in quality, due perhaps to a different pasture composition or treatment of the area or to threshing at different times or under different conditions, it is advisable for the farmer to keep the two parts of the

line separate and to advise the firm accordingly. The variation may be noticed by the storeman at sampling, when the line comes in, but if it is overlooked and the sacks are not marked, dressing difficulties are created, as a separate dressing of each part cannot be carried out. Also sacks the contents of which are obviously dirty or sacks containing seconds should be marked before they leave the farm so that they will be easily identified and handled separately in the store to ensure uniformity in dressing. It is usual for lines of seed being dressed on account of clients to be dressed in the order in which they come into the store. When the line is taken down from the stack for dressing the seed is tipped into the hoppers and the sacks put aside for cleaning. An efficient sack cleaner is a . very necessary piece of machinery in a seedcleaning store. All types of seeds cling to the sacks inside and out, particularly seeds such as hairgrass, Italian ryegrass, sweet vernal, burr clover, and other rough seeds. A good sack cleaner removes all these seeds and the sacks may then be used as clean “once-shot” containers for seed, seconds, offals, meals, and other purposes.

On coming off the dressing machine the machine-dressed seed is generally put into new sacks, each containing a standard weight of seed. After being sewn, the sacks are branded with the identification line number of the firm and a description of the seed. In the case of Certified seeds official samples are then drawn and the sacks are tagged and sealed. The seed is then ready for further storage, which means restacking, or for. removal from store. The outward weight is the net weight of machine-dressed seed. The various

seconds and offals extracted are also bagged and their descriptions and weights recorded. Seconds and Offals Farmers frequently have the impression that a lot of good seed goes out in the seconds or offals at machine-dress-ing time. Seconds is the name usually given to the best of the dressings taken from the firsts or machine-dressed seed, while offals refers to the other grades of seeds, weeds, and rubbish which are extracted at machine dressing. An examination of samples of the various separations will show that there is little that could be made use of in seconds and offals. However, sometimes the seconds consist of seed which would warrant further dressing or disposal as seconds. This seed is not as a rule mixed with the firsts, as its purity may not be so high and it may spoil a good line of firsts, but sometimes if of similar quality the seconds may be run back through the machines into the firsts. An example of this is where shelled cocksfoot the purity and germination of which are usually as good as those of the firsts is run back in order to. increase the bushel weight of the line.

There are instances where two varieties of seed, such as perennial ryegrass and white clover, are harvested together. When this happens the seed dresser aims at getting the most of both varieties by dressing, say, the perennial ryegrass, and extracting most of the white clover in one line, which is then dressed separately on the clover machines. Again, a reasonably pure line of white clover may be separated from a mixture of white and suckling clovers without detracting from the value of the mixture still remaining. In any event, seconds which may be usable are kept by the dressing firm for instructions from the owner of the seed. Genuine offals, however, have to be dumped or destroyed. Though some types of offals have food, value when sterilised, ground, and mixed in stock meal—a practice adopted during the war to utilise the feed value of an otherwise waste —better foodstuffs are now readily available for stock meals and the practice , has generally ceased. Seeds Cleaned in New Zealand A great variety of grass and clover seeds is produced on New Zealand farms and cleaned by New Zealandmade machine-dressing plants. In the cleaning process each variety of seed . has its own peculiarities and difficulties. There are impurities which due to size and shape will obviously be important when present in certain seeds but which are of no moment in others. Consequently it is desirable to discuss separately each of the seeds more commonly handled. Perennial ryegrass: As the very high purities indicate, the cleaning of perennial- ryegrass now, as 40 years ago, presents few difficulties. However, it is possible to strike trouble in some lines because of the presence of goosegrass which has . its awns broken off or is partly or completely shelled. If the awns are left on by the farmer in his harvesting operations- (by light threshing), there is generally little difficulty in removing the goosegrass. Farmers with

goosegrass in their perennial ryegrass seed production areas should therefore take every care to avoid damage to this seed during threshing. Hard threshing also breaks up straw into small pieces, some of which,. being similar in size and shape to ryegrass, may prove difficult to remove in dressing. Cocksfoot, English trefoil in the shell, sweet vernal, and hairgrass are other impurities which occasionally cause difficulty in dressing perennial ryegrass. t Italian ryegrass and short-rotation ryegrass: As Italian ryegrass and shortrotation ryegrass are harvested from young pastures only, there are normally. fewer impurities present in the paddock than with many other seeds. Those most likely to present trouble, to the seed cleaner are goosegrass and hairgrass. Well-developed ribgrass, unshelled white clover, wild oats, and sweet vernal are other impurities which it is difficult to remove entirely from Italian ryegrass. Cocksfoot: Of the main grass seeds perhaps the least satisfactory job. is made of cleaning cocksfoot because of the great difficulty in removing inert matter consisting mainly of husks which do not contain kernels. Small perennial ryegrass seed, which is of a very similar size and shape to cocksfoot, is also difficult to separate. Cocksfoot seed should therefore be harvested from areas as free as possible from perennial ryegrass. Minor impurities in cocksfoot are goosegrass, ribgrass, Yorkshire fog, and catsear. Crested dogstail: In crested dogstail seed Yorkshire fog may be the worst impurity, particularly when it is small and becomes shelled, as it may then be almost impossible to separate. Other impurities .difficult to eradicate are sweet vernal, hairgrass, white clover, chewings fescue, and small perennial ryegrass. Chewings fescue: The most objectionable weeds encountered in dressing this seed are catsear, sweet

vernal, small ryegrass seed, and hairgrass. Catsear is the worst of these, as, being the same shape, size, and weight as fescue, it is frequently not removed by the riddles or by the cylinders. Timothy: An increasing quantity of timothy seed is being harvested in New Zealand, mainly in Southland and Otago. Generally the worst impurity in this seed is Yorkshire fog. White, alsike, and suckling clovers are also hard to remove during .dressing, and management of timothy seed producing areas should aim at the elimination of these plants as much as possible. Timothy is often appreciably shelled during dressing, but this seed seems to germinate just as satisfactorily as unshelled seed. Browntop: Two of the worst impurities in browntop are toadrush and yarrow, which are practically impossible to eliminate entirely. Other minor impurities are chickweed, white clover, English trefoil, and hairgrass. An impurity sometimes present and impossible to remove altogether is buck’s horn plantain. A large quantity of straw is present in some lines. This is easily separated, and, as dressing charges are based on inward weights, it may pay the farmer to put the line over his header to eliminate some of this waste material before sending it into store. White clover: As the main clover seed produced in New Zealand, white clover has always received particular attention from seed-dressing plants. As with most other seeds, a high standard of purity is generally obtained. Should suckling clover be present in quantity in the field-dressed sample, however, it is not possible to make a clean separation at machine dressing and there must then be heavy dressing losses if it is desired to obtain white . clover seed with a reasonably high purity. After suckling clover, the worst impurities are sorrel (with the wings removed), shelled fog, clustered clover, and timothy.

Cowgrass and Montgomery red clover: The worst impurity in red clover seed is damaged red clover seed itself. If the farmer during his threshing sets his machine too hard, or if he threshes his crop out of condition, he will certainly get a higher proportion of chipped and broken seed. Redressing of such seed may cause to show up even more broken seed which had been damaged at threshing. Badly broken seed can be removed fairly readily, but slightly chipped seed will give most cleaning plants a problem that they cannot handle to either their own or the grower’s satisfaction, as it is practically impossible to eliminate this seed which has been injured very slightly from the whole seed. Ribgrass, sorrel, and dock seeds are impurities which are also most difficult to separate completely by machine dressing. The presence of dock seed in red clover has caused complaints from the English market. Other impurities are white clover and dodder. Subterranean clover: A small but increasing area of subterranean clover is harvested in New Zealand, principally in Marlborough. Owing to the method of harvesting, small stones and soil particles are very common impurities in subterranean clover seed, but although they are troublesome they can usually be separated at machine dressing. Chipped and broken seed may be a bad impurity; this is caused by hard threshing in freeing the clover from the cob. Other impurities which may be difficult to remove entirely are wild turnip, vetches, rape, and striated clover. Lucerne: Probably the worst impurities in lucerne are ribgrass and red clover. Other impurities which at times are hard to remove altogether are wild turnip, ryegrass, goosegrass, hairgrass, and striated clover. Purity Standards In the seed trade the main basis of dealing is on a minimum requirement of 98 per cent, purity and 90 per cent, germination (with the exception of

cocksfoot). Generally there is little consideration on the export market for lines of seed which fail to meet these requirements, though as far as germination is concerned this may depend on seasonal conditions. With the main seeds purities of 99 per cent, and over are very common. Emphasis has been laid on the good job done by most seed-dressing plants. This may be so, but it is as well for the farmer to remember that a line of seed with a purity of 99.8 per cent, and containing as little as 0.1 per cent, of seed of a particular weed or weeds may be unsafe to sow and may be prohibited from importation into other countries. For instance, seeds containing even a trace of bindweed, hoary cress, or dodder are prohibited entry into Australia, U.S.A., and Canada, while lines containing Californian thistle are . prohibited entry into Australia and U.S.A. Again, nassella tussock, ox-eye daisy, milk thistle, and tarweed are totally prohibited in seeds for Australia. Other common weeds which, if present in seeds in excess of a restricted quantity, depending on the seriousness with which the impurity is viewed, will prevent the entry of seeds into Australia are horehound, field madder, ■ stinging nettle, Australian flax, stinking mayweed, curled dock, creeping buttercup, wireweed, spurry or yarr, and ribgrass. Therefore it is necessary to realise not only that a high purity is important, but that freedom from particular impurities may also be essential. Capacity of Plants and Dressing Losses Owing to the different arrangements and types of machinery used by different firms, as well as the widely differing state of lines of field-dressed seed, there is no fixed rate for the dressing of any particular grass or clover seeds. However, one typical

large plant when dressing ryegrass puts into the machines about 20 to 30 bushels per hour of field-dressed seed and puts . into the clover machines about 500 to 6001 b. per hour. The outward weight, of course, varies to a great extent, and may be lower than 20 per cent, or higher than 80 per cent, of the inward weight, depending on the impurities taken out. Again, as has been explained it may be necessary to put a line over the machines twice, and this naturally halves the dressing rate. Whatever the rate, it should be remembered that machine dressing is a process which cannot be hurried, but must be done thoroughly if it is to be satisfactory. Effect of Certification on Seeddressing Procedure Now that the bulk of the seed dressed is either certified in the paddock or entered for certification in store after dressing, every care has to be taken to ensure that there is no chance of contamination at the machine-dress-ing stage.' In the larger stores the procedure may be simplified; for example, in the case of the ryegrasses one machine will perhaps handle only lines of perennial ryegrass which are to be entered for certification by type test, whereas another machine takes only seed which has already been certified in the paddock. Another machine will deal with lines of Certified Italian ryegrass. There is then no chance of different types of ryegrass being mixed. However, all firms do not have sufficient plant to be able to do this, but they simplify matters by dressing, say, all lines of available Italian ryegrass first. Then the machine is given a very thorough cleaning down and uncertified perennial ryegrass lines may be put through. After another thorough cleaning, the

Certified perennial ryegrass lines are dressed. In view of the high proportion of the total seeds dressed .which are certified it may fairly be said that all dressing firms now keep the rules of certification in mind when they are cleaning the seed. The result is that there is every co-operation between the seed-dressing firms and the officers of the Extension Division of the Department’ of Agriculture, which makes for easier working on both sides. Extent of .Seed Cleaning in New Zealand Seed-dressing stores are ' usually stationed at all the centres of seedgrowing areas. The number, at any one centre may vary from a single plant to half a dozen or more. Of the 87 plants in operation 64 are in the South Island and 23 in the North Island. In addition 16 mobile or portable seed-cleaning outfits work from farm to farm in-the main seed-growing areas of the South Island dressing grain and small seeds. The Human Element The quality .of the work done by seed-cleaning machinery depends finally on one thing—the efficiency of the men operating the machines. An experienced storeman with the ability to sum up a line and gauge what will be required in the dressing, process is the ’ first essential. Then the men in charge .of each machine require long experience in the handling of their machines, in the adjustment of riddles and cylinders, and in the degree of blast or suction to apply as well as in the choice of the correct size of riddle or cylinder for the seed in question. Due to the great variation in the composition of field-dressed seed, no two lines can be treated exactly alike. This calls for good judgment on the part of operators. I It is not only in the operation of the machines that good judgment is required; ability to repair machinery and make up and improve suitable parts on the job is another requirement of a good storeman. Again, the way in which machines are set up, that is, the combination of riddles, cylinders, etc., and the part played by machines such as the dossor, all call for good judgment on the part of the storeman. The very high standard generally of the work done in seed-dressing stores shows that the men responsible are doing an excellent job.. The Farmers" Part This article has been concerned mainly with the work of . actual machine dressing and not with the harvesting and other farm operations leading up to the production of the field-dressed seed. This aspect has been dealt with in the articles which have appeared in the “Journal” on the production of each of the main varieties of seed. However, it is not out of place to mention some of the principal ways in which a farmer may make the work of the seed cleaner easier and in so doing improve the/quality of his own line and reduce the cost of dressing to himself. In the first place the advice of a leading member of the seed-cleaning industry is sound: “Leave the seed as much as possible as nature produces

it”. That is, it is never wise to thresh too hard and possibly knock the awns off seeds such as goosegrass, hairgrass, or Italian ryegrass, or damage and chip clover seed" in trying to get it out of the cob. Seed that has been knocked about, whether it is the impurity or the actual variety to be dressed, is all the harder to dress. This applies to all seeds. On the other hand too much straw and seed stalk should not be left in the sample, as this merely increases dressing costs needlessly. Sometimes seed comes into store badly damaged, due probably to ignorance of correct harvesting technique. The only advice that can be offered in such cases is to follow carefully at harvest time the instructions of the manufacturer of the header harvester and to seek advice if in doubt. At harvest time the farmer should keep sampling and examining the seed at intervals throughout the day, as changing atmospheric conditions may affect considerably the necessary header harvester settings. Before seed is sent in 'to be cleaned it should be thoroughly dry. Damp seed is only a nuisance in store, as it is difficult to dress. It is also lowered

in value because of discoloration and

musty, smell and it may even heat or char in store. Where merchants are aware of the fact that the seed is damp and are prepared to deal with it as a salvage operation, of course that is a matter for the farmer and the firm concerned. Whatever the cause, no seed should be sent into store damp unless the merchant is aware of the fact and is prepared to deal with it. The production of good seed starts from the preparation and sowing of a paddock. Everything possible should be done to keep the paddock clean by sowing under the best conditions, by grazing the paddock in the way best suited for the seed to be saved and for control of weeds, and by harvesting the seed in the best manner. In other words, clean seed production should be regarded as a specialised job under good farm management conditions in order that the end ' product, the machine-dressed seed, might be of the highest quality. ACKNOWLEDGMENTS The writer wishes to acknowledge with thanks the help and information provided (and used in the compilation of this article) by Andrews and Beaven Ltd., Wright Stephenson and Co. Ltd., and the Canterbury (N.Z.) Seed Co. Ltd., all of Christchurch.

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LIST OF BOTANICAL NAMES OF PLANTS MENTIONED IN ARTICLE ' . vrw,,.,.. -«S T .

Common name Botanical name Common name Botanical name Alsike . . . . Trifolium hybridum Meadow- foxtail . . Alopecurus pratensisAustralian flax . . Linum marginale ■ Milk thistle . . Silybum. marianum Bindweed .. ..Convolvulus arvensis , Nassella tussock .. Nassella trichotoma Browntop . . . . Agrostis tenuis ’ Buck’s horn plantain Plantago coronopus p aspallim . . . . Paspalum dilatatum * Californian thistle . . Cirsium arvense Perennial ryegrass . Poliv/m, perenne Catsear . . . . Ilypochaeris radicata Phalaris ... . . Phalaris tuberosa Chewings fescue . . Festuca rubra var. Red clover . . . . Trifolium pratense commutata Ribgrass . . . . Plantag o lanceolata Chickweed . . . . Rtellaria media Sorrel . . . . Rumex acetosa and Clustered clover . . Trifolium glomera- Rumex acetosella turn Sparry or yarr .. . Spergula arvensis Cocksfoot .. -. Dactylis glomerata Stinging nettle . . Vrtica dioica Creeping buttercup . Ranunculus repens Stinking mayweed . Anthemis cotula Crested dogstail . . Cynosurus cristatus Striated clover . . Tri folium striatum Danthonia . . •.. . Danthonia pilosa and Subterranean clover . Trifoliwm subterDanthonia semi- raneum annularis Suckling clover . . Trifolium dubium Dock (broad) . . Rumex obtusifolius Sweet vernal . . Anthoxanthum Dock (curled) . . Rumex' crispus ' odoratum _ Dodder . . . . Ouscuta epithymum Tarweed . . . . Odontites viscosa English trefoil . . Medicago lupulina Timothy . . . . Phleum pratense Field madder . . Sherardia arvensis Toadrush . . . . Juncus bufonius Goosegrass . . . . Bromus mollis Vetch . . . . Vieta _spp. Hairgrass ... . . Vulpia spp. White clover . . Trifolium repens Hoary Cress . ... Cardaria draba Wild oats . . ■. . -Avena fatua.. Horehound .. Marrubium vulgare Wild turnip .. Brassica campestris Italian ryegrass .. Lolium multiflorum Wireweed .. . . Polygonum aviculare Lotus major . . Lotus major Yarrow. ... . . Achillea millefolium Lucerne . ..’ . . Medicago sativa Yorkshire fog . . Holcus lanatus

Photographs on opposite page by Green and Hahn Photography Ltd.

Photographs on opposite page by Steffano Webb. .