Herbage Seed Production
The case for producing herbage seeds in this country is fourfold. If we are to embark upon ley farming on a grand scale we must have an abundance of the correct seeds. The bred pedigree strains should contribute in large measure to the needs of the advanced ley farmer. These strains, if they are to be maintained in a proper state of purity, must be grown under adequate supervision and under a well-planned system of certification: home production is therefore practically essential. For some time, many kinds of herbage seeds will be in short supply and difficult to import, so that on this score also home production becomes essential. Seed production affords the opportunity to the progressive farmer of developing an exceedingly interesting and remunerative sideline. The growing of herbage seeds, moreover, fits into a ley-farming rotation in an admirable manner. Within wide limits the management can be flexible, for in the case of broadcast sowings (as is applicable with perennial ryegrass and white clover), the seed-producing fields can be left down in sward for a few years after the seed crops have been harvested, or seed crops can be taken periodically from such fields. The straw derived from a herbage seed crop is of relatively high feeding value, and this is markedly so in the case of the leafy pedigree strains of perennial ryegrass, which as a feed is comparable with good meadow hay.
The Pedigree Bred Strains and Certification
If the farmer desires to grow Aberystwyth-bred strains under the scheme of certification he must either be a member (or become a member) of an approved growers' association, or he must grow seed under contract for an approved merchant. Under the certification scheme the grower must obtain stock seed from Aberystwyth, submit to certain regulations and to the inspection of his standing crops. If the crop is satisfactory it will be certified and by virtue of its approved standard of excellence it will qualify for sale at the price ruling for certified seed.
The essence of the certification scheme is to ensure purity of strain, and consequently growers who come into the scheme must be prepared to take all necessary precautions to that end. Difficulties arise from the fact that both grasses and clovers are cross fertile, the pollen of the grasses being wind-borne and that of the clovers carried by bees. The precautions necessary to ensure reasonable isolation will be discussed later in this chapter.
Those who are unwilling or unable to come into the certification scheme need not feel debarred from embarking upon seed production. Since ruling prices are now (1941) high and the demand increasing quite good prices should be obtainable from non-certified seed of the pedigree strains. Farmers would also be well advised to consider growing enough seed for at least their own use, or to meet a quite local demand. Provided crops will be harvested free from harmful weed seeds, like docks, Yorkshire fog and buttercups, elaborate cleaning and dressing of the seeds is really quite unnecessary. Both in the farmer's and in the national interest it is adequate supplies of seed that under present conditions matter before everything. Farmers growing seeds to meet their own and their neighbours' demands must remember that sales from farmer to farmer must conform with the regulations of the Seeds Act, and consequently the seeds must have been tested at the Official Seed Testing Station, National Institute of Agricultural Botany, Huntingdon Road, Cambridge, so that the necessary declaration can be made in respect of the germination and purity of the seed. (Purity here refers to freedom of admixture with the seeds of other useful species and of weed seeds, and not to genuineness of strain or variety.)
The technique of seed production demands considerable care and rigid attention to detail at all stages. The yields so far obtained by some growers have been disappointing and in nearly all cases these poor yields have been due to faulty management, and frequently to insufficient attention to proper manuring. Herbage seed production has been studied in great detail by our colleague Mr. Gwilym Evans, who is the Officer in Charge of Seed Production at the Welsh Plant Breeding Station, Aberystwyth, and who has maintained close touch with the growers' associations, and has played an important part in the developments that have taken place. The particulars which follow are summarized from various articles written by Mr. Evans and are based on large numbers of experiments, and on experience gained during intensive study in the field.
Precautions to Ensure the Purity of Strains
Spacial isolation is of the first importance. At least 200 yards should separate a seed field from a meadow or ill-grazed pasture containing the same species as the seed crop. Flowering on pasture fields can, however, be prevented by sufficiently close grazing, or by the use of the mowing machine at the proper time. In the case particularly of cocksfoot, and in some districts of timothy also, care must be taken to cut down such plants in hedgerows, headlands and farm lanes before they come into flower. The farmer specializing in the seed production of pedigree strains should only use in his seeds mixtures for ordinary purposes those strains of the several species which he is also growing for seed. He should select as seed-producing fields such as are remote from the grass fields of his neighbours. The members of a growers' association, of course, meet each other helpfully in the selection of fields, and in the choice of strains grown for seed. A fruitful source of contamination is the viable seed that may spring into growth from the spread of yard manure that is not well rotted; from the carrying-out of hay on to fields, and when an old turf is ploughed down. It is consequently risky to grow seed as the first crop on either newly ploughed permanent grass, or on a newly ploughed ley, and only well-rotted dung should be employed on seed-crop fields, while hay should not be carried out on such fields. Finally, great care must be taken to have thoroughly cleaned-out clover hullers and grass threshers before starting to machine pedigree seeds. In practice these simple precautions are not difficult of fulfilment, and it will pay the farmer to gain the reputation for being a skilled and reliable seed grower whose crops are always well up to the standard of certification.
Soil and Climate
Deep, free-working loams produce the most consistently high yields of herbage seeds. Clover seed crops are, however,. affected more by weather than by soil; grasses, on the other hand, are more greatly influenced by soil conditions. The leafy strains of the grasses to produce abundance of seed must be made to grow luxuriantly, and they demand, therefore, soil in a high state of fertility. On the other hand, excellent crops of red and white clovers can be produced on land of only medium fertility: very rich land is prone to produce excess of clover foliage. Clover seed production succeeds best in districts where the average annual rainfall is not greatly in excess of thirty inches, while grass seed production can be successfully carried into districts where the annual rainfall exceeds forty inches. Excellent crops of perennial ryegrass seed have been harvested in regions of high rainfall at elevations up to 1,000 ft. above sea-level.
Method of Sowing
Red clover, white clover, perennial ryegrass and Italian ryegrass may be sown for seed broadcast under corn and this method is also applicable to ordinary timothy and cocksfoot. The leafy strains of timothy and cocksfoot, and also meadow fescue and red fescue, produce much the best seed crops when sown in widely spaced (about twenty-four inches apart) drills. The leafy strains of perennial ryegrass also produce their maximum seed yields when sown in drills, but other advantages, on the balance, weigh in favour of broadcasting. In the following statement the normal seed rates both for broadcasting and drilling are set out for the chief species and the yields of dressed seed that are to be expected are also shown.
Particulars as to Seed Rates for Sowing and Yields of Dressed Seed per Acre Species of Clover or Grass Seed rate in lb. per acre Yield of dressed seed in lb. per acre Broadcast Drills 24" apart Normal yields Maximum yields under good management in recent years Red Clover 5-9 - 300 700 White clover 3-5 - 150-200 400 1 Perennial ryegrass 16-30 4-6 300-400 650 2 Italian ryegrass 20-35 - - - Timothy 14-18 3-5 300-450 650 Cocksfoot (Danish) 16-24 - - - Cocksfoot (all strains) - 4-6 350-600 1,100 Meadow fescue - 5-7 400-500 600 3 Red fescue - 4-5 250-350 450 4 Notes
1 Wild white even once-grown would not be likely to reach a yield of 300 lb. Aberystwyth S. 100 has, however, frequently yielded up to 3001b.
2 The figures refer to the pasture strains: the hay strain Aberystwyth S. 24 usually yields 500 lb. and has reached 1,000 lb.
3 Figures for Aberystwyth S. 53.
4 Figures for Aberystwyth S. 59.
The heavier seed rates are recommended only when the expectation of good establishment is not high, such as on light soil in dry districts, under conditions of indifferent tilth, or of relatively low fertility, or when the growth of a cover crop is rather too advanced before the herbage seeds are sown.
Where sowing in drills it is essential to have cleaned the land thoroughly and to have commenced hoeing at the earliest possible stage. Since grass seedlings come away rather slowly it is always wise to mix about 1/2 lb. of white mustard per acre with the grass seeds. The mustard rapidly shows up the rows. The mustard must be grazed or mowed off before it comes into flower.
In districts of low rainfall growers should aim at sowing broadcast as soon as a good tilth can be obtained during the latter half of March, and it is important that the leafy strains of the grasses should be sown at the same time as the cereal nurse. Wide drill crops should be sown without a cover crop towards the end of March, and in western districts during April. Drills can be sown in the corn crop, but the yield of seed in the first harvest year will then be slight, and it will often be necessary to defer taking a seed crop until the second harvest year.
If land is free of crop, and is clean, and in good heart, there is much to be said for sowing wide drills in say the first week of September. The advantage is a far better control of annual weeds than after spring sowing. No seed crop could, of course, be expected in the summer after autumn sowing, except from the ryegrasses which can produce fair crops of seed after early autumn sowing.
Companion seeds can be employed for either of two purposes:
(a) to assist in the proper handling of the main seed crop, or
(b) to give rise to a supplementary seed crop and to assist in the subsequent development of a useful sward.
Thus it is a sound practice to add about 5 lb. to the acre of timothy to the seeding of late-flowering red clover. The timothy will induce farm stock to graze the clover herbage more evenly before the stand is put up to seed. Again, if about 4 lb. of timothy is added to the broadcast sowing of the leafy strains of perennial ryegrass, the timothy will assist the ryegrass to stand, will make it easier to harvest the crop with a binder, and because the timothy is longer in the sheath than the ryegrass, it will facilitate tying and 'capping' the stooks.
Wild white clover, or Aberystwyth S. 100 white clover, can also be added to the broadcast sowing of the bred leafy strains of perennial ryegrass. The white clover will help to form a high-grade pasture after a crop or two of ryegrass, seed has been taken, or, under appropriate management, a crop of white clover seed can be harvested towards the end of the life of the ley. Aberystwyth S. 100 white clover synchronizes fairly well with pasture ryegrass in seed ripeness and dual crops of ryegrass and clover can be harvested. Such clovery-ryegrass crops cannot, however, be successfully harvested with the binder, and must either be cut and harvested in the manner of hay and threshed on the field (a procedure which demands ideal weather conditions) or with a combine harvester with an efficient 'pick-up', but this latter procedure postulates adequate means for seed drying.
In the case of all the herbage seed crops we are here considering, except broad red clover and Italian ryegrass, the plant stands can be left to hold the land for at least two years, and in many cases for three or four years. Thus with the late-flowering red clovers sometimes it is possible to take a seed crop two years in succession, or the seed crop may be deferred until the second year. With broadcast pasture strains of perennial ryegrass, crops are frequently taken two years in succession, while with wide drill crops of the leafy strains of cocksfoot and timothy three seed crops in succession are frequently taken, and under very careful management four, or even five, successive crops have been harvested. The question of manuring is, therefore, of the greatest importance. For perennial ryegrass, equally with the clovers, it is imperative that the lime status of the soil is maintained at a high level. For full clover harvests phosphates and potash are absolutely necessary, and autumn applications of 5 cwt. high-grade slag, and 2 cwt. potash salts per acre are normally recommended. For the grasses nitrogen in adequate amount is essential to the production of full crops, and therefore seed yield is largely determined by the wise employment of nitrogen; at the same time it is desirable to maintain the phosphatic and potash status of the soil at reasonably high levels. The following brief notes will serve as useful guides to the grower.
In drill-sown crops abundant tillers must have been produced by the autumn. In the seeding year if tiller development is not satisfactory, 1-2 cwt. nitro-chalk per acre should be applied early in the autumn. For crops after the first, 2-4 cwt. of a complete fertilizer should be applied each early autumn. Spring dressings are also necessary, for the first year's crop 1-2 cwt. per acre of sulphate of ammonia should be applied to cocksfoot and timothy drills from mid-March to April; for later crops the spring dressings should be somewhat increased, unless yard manure is available.
For broadcast crops of perennial ryegrass as soon as the corn crop has been harvested it is usually desirable to apply 1-2 cwt. of nitro-chalk, and no further application should be necessary for the first crop. If consecutive seed crops are to be taken well-rotted farmyard manure, or a complete fertilizer, should be applied in the autumn, and nitro-chalk or ammonium sulphate in the spring.
General Management of the Plant Stands
Drills must be kept clean and well cultivated, but the cultivations must not be deep after April. Stands of grass species should not be grazed in the seeding year unless growth is very forward; perennial ryegrass will stand autumn grazing better than will cocksfoot or timothy. Even when the stands are established autumn grazing must not be too heavy, and after September should only be sufficient to remove excessive foliage liable to winter burn. With drills it is best to cut off or graze off the leafage as soon as possible after the seed has been harvested, and then to leave the drills to grow right on to the next seed crop: they should on no account be grazed in the spring. Broadcast stands of perennial ryegrass should not be grazed in the spring, to do so tends to decrease seed yield as such and also to encourage too great a development of white clover.
Moderately hard grazing in the autumn is permissible for clovers. In order to obtain good yields of clover seed the stands should be grazed in the spring to an appropriate date. Generally speaking, late-flowering red clovers should be grazed on the 'on' and 'off' basis until the end of May. The early, or broad red, clovers produce the heaviest seed yields if grazed until June, but most usually growers prefer to take a hay crop in June and then to put up for seed. The early Aberystwyth S. 100 white clover should be grazed until the middle of May, and wild white clover should usually be grazed until the middle of June.
In all cases the intensity and lateness of grazing must depend upon season and soil: on dry soils and in dry seasons over or too late grazing of clover must be avoided.
Seed Ripeness and Dates of Harvest
With the exception of timothy the grasses are usually ripe for harvest between the hay and corn crops. Timothy and red clover are ripe after the corn crop. Hay strains of perennial ryegrass (e.g. Aberystwyth S. 24), are seed-ripe during the first fortnight of July. Cocksfoot strains are ripe within a few days of each other towards the middle of July. The pasture strains of perennial ryegrass (e.g. Aberystwyth S. 23 and S. 101), ripen somewhat later in July than the cocksfoot strains. Leafy strains of timothy ripen in western districts during the latter half of August, while pasture strains may not be ripe until the first week of September. The early types of meadow fescue ripen about the same time as the hay strains of cocksfoot and the pasture types a few days later.
The above are average dates; in exceptionally warm and dry summers ripeness may be a week earlier, and in wet summers may be later by a considerably wider margin.
Aberystwyth S. 100 white clover is usually ready for cutting at the end of July or early in August, and wild white clover about the middle of August. The harvest dates of the red clovers are particularly sensitive to management and weather conditions. The late red clovers usually come for harvest from the middle of September to October, and the broad red clovers towards the end of September to October.
It is not easy to estimate seed ripeness, and experience in handling the crop is necessary; the following notes should, however, prove helpful to the grower:
The hay strains are ripe when the heads have turned a brownish colour and when the straw is of a brownish-yellow tinge. Ripeness in the pasture strains is more deceptive, for the straw often retains its green colour when the seed heads are quite brown and the seed dead ripe. A little shedding of the seed from the earlier heads must be allowed before the bulk is ready for harvest.
Harvest the leafy strains of timothy when from 30 to 60 per cent of the heads have shed a slight amount of seed at the top.
Cut when the crop has a light brown appearance, the straw yellow below the head and when the seeds have only a tinge of green left.
Do not be deceived by the greenish straw and cut the crop when the heads are greenish-brown.
The crop will be ripe when the majority of heads have turned brown, when the flower stalks are yellowish-brown below the heads and when the seeds are hard and the majority dark purple. Care must be taken to note whether the earlier heads, the medium heads, or late heads have most seed, and to act accordingly. Generally the early heads contain but little seed.
The crop should be harvested when the majority of the heads are light brown, when the seeds are yellow and the majority hard.
The horse-binder and the power-binder can deal with the ryegrasses, cocksfoot and timothy. These grasses should be cut and bound into narrow sheaves, and those of timothy and cocksfoot are frequently as long as those of wheat. It is best to cut the crop in early morning or evening, and the sheaves should never be allowed to lie on the ground overnight.
Grass seed crops are not usually left in stook for longer than a week and whenever possible they should be threshed off the field.
Clover seed crops are generally cut with the grass mower. When white clover crops are short, they can be dealt with by attaching a galvanized iron or tin sheet behind the cutter bar, with a man, or a boy, in attendance to draw the crop into heaps. In the case of clover crops, and of grass crops (e.g. perennial ryegrass), which because of lodging may have been cut with the mower, tripods are of great value in drying the crop.
In New Zealand seed strippers are commonly used in white clover crops. They can also deal with perennial ryegrass that is not too long in the straw. There is considerable scope for improving the design of strippers for use in this country.
Ordinary corn threshers are normally used for most grass seed crops. Many of these have a set of linseed screens which are well suited for ryegrass and cocksfoot. Clover hullers are suitable for the threshing of the leafy strains of timothy, as it is always difficult to remove the chaff from the seed of these strains. In both the threshing of grasses and the hulling of clovers care must be taken properly to adjust the machines, and the reader should refer to the more detailed particulars given by Evans with reference to the all-important question of threshing.
Seeds with any suspicion of dampness should be dried immediately by artificial means, or, in the absence of a drier, spread on an airy floor and turned thoroughly every day. Grass seeds should not be stored in bags until the moisture content has been brought to 12 per cent, or lower. When clover has been threshed from crops in a proper condition it is generally sufficiently dry to be stored in bags.
EVANS, GWILYM (1942). 'The Production of AuthenticatedHerbage Seed.' Journ. R.A.S.E. Vol. 103.
EVANS, GWILYM. 'Herbage Seed Production.' War Food Production Advisory Bulletin No. 3. Issued by W.P.B.S., Aberystwyth.
Next: 17. Rotations and the Need for Simple Experiments
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