Avena sativa L.
|Author: J.M. Suttie|
Oats, avoine (French), hafer (German), avena (Italian and Spanish),
A tall annual cereal, widely grown as a fodder in temperate and sub-tropical countries, also does well in the high-altitude tropics. Oats are only known as a cultigen, of uncertain origin, but were known to Lake Dwellers of Europe. It is now cultivated throughout the temperate zones of the Old and New Worlds as a summer crop and in the sub-tropics as a cool-season crop (mainly as forage); they are also a good forage in the high altitude tropics. Oats are believed to be derived chiefly from two species, wild oat (A. fatua L.) and wild red oat (A. sterilis L.).
The green plant is a good forage and makes good hay and silage. The straw is a useful roughage. The grain is an important livestock feed and the unhulled, crushed fruit is the usual form in which it is fed to ruminants and horses. Oat forage, hay, straw and grain are renowned horse fodder.
Oats grain is used widely for human consumption. While oats are still widely used for breakfast cereals, their use as a staple in northern Europe has decreased with the easier availability of imported wheat; a wide range of oat recipes is given by MacNeill 1929.
Avena sativa L. An annual grass to 1.5 meters high; culms tufted or solitary, erect or bent at the base, smooth. The leaves are non-auriculate, green and the sheaths rounded on the back; ligules blunt, membranous. The inflorescence is a diffuse panicle with 2 3 florets, all bisexual or the distal one or two may be reduced and male or sterile; glumes sub-equal 7 11 veined, longer glume 17 30 mm; lemmas 7 9 veined, either bifid or with a bristle at their apex; lowest lemma 12 25 mm. (2n = 42). The rachilla of the cultivated oat does not disarticulate at maturity (that of several weed species do). Its lemmas are rarely awned. The grain is tightly enclosed by the hard lemma and palea. Seed size varies with cultivar, it is commonly about 30 000 seeds per kilogramme.
Avena sativa subsp. byzantina (C. Koch) C. Romero Zarco = A. byzantina C. Koch., the Red or Algerian Oat, differs from A. sativa in that its rachilla eventually breaks off just above each floret and remains attached to the next floret above. It is a minor Mediterranean crop.
Avena strigosa Schreb, the Bristle Oat has stems to 1.2 meters, like A. sativa its rachilla does not disarticulate on maturity. Spikelets similar to common oat but smaller; longer glume 15 26 m; lower lemma 10 17 mm, usually glabrous and with two apical points 3 9 mm and two smaller, finer bristles alongside (2n 14, 28). A minor crop of poor soils and hard climates.
Wild oats are a pernicious weed of cereal crops. Several species are involved, the main ones are the spring or common wild oat Avena fatua L. and the winter wild oat is Avena ludoviciana Durieu = A. sterilis subsp. ludoviciana (Durieu) M. Gillet & Magne. These are useful grazing in fallows but the damage they cause in subsequent cereal crops outweigh their forage potential.
The common oat, A. sativa cultivars are by far the most widespread; A. byzantina is adapted to warmer, subtropical conditions; the bristle-pointed oat A. strigosa is adapted to poor soils and low summer temperatures and has been cultivated for grain and straw in the more mountainous parts of Northern Europe and in places in Eastern and Central Europe where conditions do not suit the common oat. A wide range of varieties is available to suit many agro-ecological conditions and different uses.
Oats, while responding to high fertility, will produce a crop on soils too poor and acid for wheat; they can be grown on most agricultural soils so long as drainage is reasonable.
In temperate climates it is usually a spring-sown crop; in sub-tropical and Mediterranean conditions it is grown in the cool season; in the tropics it is grown at altitude: in Kenya, on the Equator it can be grown from 1 600 metres upwards but is best above 2 000 metres and excellent at 2 800.
Cultivation and management
Only forage production is described; as a cereal they should be treated as other white straw crops. Oats may be grown in mixture with annual, twining legumes such as peas and vetches but it is essential that the growth cycles of the two crops match, otherwise the legume will have dried and shattered before the oats are at the cutting stage. They are a very useful nurse crop to grow with winter clovers such as Egyptian clover (T. alexandrinum) if used at light seed rates so as to give the establishing clover enough light to grow; the faster-growing and more cold-resistant oats provide early cuts at a season when green feed is scarce and clover growth stopped or very slow.
Time of sowing varies widely according to the wide range of climates where oats are grown. In areas of very cold winters they are spring sown; in temperate climates both autumn and spring sowing occurs; in the Mediterranean and sub-tropical regions they are mainly autumn-sown for hay; in the high altitude tropics they are sown at the onset of the rainy season.
A clean, well prepared seed bed should be prepared and basal fertilizer applied according to local experience; seed is drilled to 4 cm deep; when machinery is unavailable it may be broadcast. Weeds should be controlled if serious. A top-dressing of nitrogenous fertiliser should be applied.
Seed rates and mixtures
Local practices vary widely and rates as low as 60 to over 100 kg/ha are used. Oats are often mixed with vetches, and sometimes peas, for hay or silage, the cereal giving support to the trailing legume; the oat seed rate should be reduced by about half; the growth cycles of both varieties must synchronise. A light seeding of oats is useful to give an early bite in Egyptian Clover. Seed may require to be dressed depending on local disease patterns.
Seed crops are grown in the same way as for a grain crop. Oats are largely self-pollinated so farmers can save their own seed for several crops provided that rogueing is carried out and the usual precautions against mechanical contamination are taken. The closely-related wild oats (A. fatua, A. ludoviciana) are serious weeds of cereal fields and care should be taken to avoid their presence in cultivated oats since the wild ones shed their seeds before harvest and would, thereafter, cause much damage in subsequent wheat crops.
Crop use and grazing management
Oats are usually mown but can be grazed; controlled, rationed grazing with electric fencing is best for young crops; if lightly grazed a second grazing will be produced. The final grazing, of course, should aim to remove the whole crop. At high altitudes in Kenya (Molo) with well-distributed rainfall, oats provide many months of grazing if carefully managed.
Mowing is easily mechanised and the crop is also suitable for harvesting by scythe or sickle.
Oats are an excellent crop for both hay and silage.
Single-cut types are mown after flowering, multicuts should be cut earlier to encourage further growth. Mowing and hand-cutting are easy and the crop gives few problems in the making of hay. With a single cut crop it should be mown once the grains are formed; multi-cuts should be mown just prior to flowering, the ultimate cut should be when the grain is well formed. Information on haymaking techniques suitable for smallholder, and on conservation of straw, is given in Suttie 2000.
Since the stems of oats are relatively thick compared to those of pasture grasses, the crop is best suited to haymaking in areas with assured dry, sunny weather at haymaking time. Oat hay is grown on a large scale in Tunisia as a cash crop by cereal farmers in the better-watered North for sale to pastoralists in the drier areas (Chedly 2000); harvesting coincides with the onset of the hot dry weather quality is usually sacrificed for quantity since hay is sold on weight and appearance alone.
Oats are an excellent silage crop in areas too cool for maize; they may be grown pure or in mixture with vetch (Vicia spp.)or peas (Pisum sativum). Harvest should be when the grain is fully formed.
See AFRIS database, Feed Resources Group, FAO Animal Production and Health Division
The cultivated species of oats are not known in the wild. A wide range of varieties is available to suit many agro-ecological conditions and different uses. Fodder varieties which provide several cuts have been developed. Breeding programmes are mainly aimed at improving grain production, although forage qualities are also screened. The greatest concentration of oat improvement work is in North America. The Oat newsletter, (Edited by James Chong, Cereal Research Center, Agriculture & Agri-Food Canada, Winnipeg, Canada) provides information on recent developments.
The effect of introduction of improved cultivars on the spread of a crop can be impressive. Oats have become a very important fodder in Pakistan in the past fifteen years or so. The crop was introduced to India by William Moorcroft, the manager of the East India Companys stud farm in Bihar, in about 1820 (Keay 1993) but their use remained largely limited to government and military farms until recently. In the fifties and sixties oats were grown for fodder but mainly to make hay for horses which at that time was the main transport animal in rural as well as urban areas but this decreased as motor transport replaced horses for road work Multi-cut cultivars of oat were developed by the Pakistan Agricultural Research Council and the Farming Systems Research Programme in Punjab did much of the initial popularisation and seed bulking of oats - the old single-cut types have now been replaced by multi-cuts. The rapid rise in the popularity of oats over the past decade and a half has been dues to the introduction of high-yielding cultivars which give several cuts including Scott and PD2-LV65). These were very rapidly accepted by farmers and oats are now a major winter forage both for on-farm use and to satisfy the vast urban market for fresh and conserved fodder. They are more cold-tolerant then the main winter fodder, Trifolium alexandrinum, and supply green forage through the difficult December January period; they are high yielding and new cultivars give at least two cuts if properly managed; seed production, cultivation and harvest are easy; the cut crop is easy to transport and stays in good condition when sent to distant markets; the forage is well accepted by stock. Such cultivars would seem to merit testing is sites of similar climate with cool but not cold winters.
Pests & Diseases
Diseases to which oats are prone include: Yellow Dwarf Virus or Redleaf, Leaf or Crown Rust (Puccinia coronate), Septoria Leaf Spot (Septoria avenae), Stem Rust (Puccinia graminis), Halo Blight (Pseudomonas coronafaciens), Loose Smut (Ustilago avenae), Covered Smut (Ustilago levis)