1. INTRODUCTION
Oats is a cereal crop which is grown widely throughout the world under different conditions of soil and climate. Varieties grown in temperate climates and in particular the U.K. belong to the species Avene sativa. Varieties grown in hot countries are derived from another wild species, Avena sterilis. In the UK oats are grown for stockfeed and for the manufacture of oatmeal and breakfast cereals. It is a useful crop because it can be grown in the cool northern areas of the country which are unsuitable for growing wheat and barley. The best oats come from the north of Scotland around Aberdeen, and oatmeal porridge is a famous Scottish food.
In Southern Africa, the crop is grown as an irrigated winter crop in the summer rainfall region and also as a winter crop in the winter rainfall region. Due to the relatively low quality of the oats grain produced in southern Africa, only a small percentage is used for human consumption, the majority being reserved for animal feeds.
- As a forage crop, being cut and fed green to stock. It can be cut several times during the growing season, provided that it is well fertilised, and will provide good quality green forage for animals, particularly for dairy cows.
- Oats can be harvested as a grain crop and sold for feed, particularly for horses. A large husk surrounds the grain, therefore oats has high crude fibre content and this makes it a very good food for horses, especially race horses in training.
Table 1: Fibre content of Oats
| Fibre % | |
| Oats | 12 |
| Maize | 2 |
| Sorghum | 2 |
| Wheat | 1.9 |
During processing the oats grain is sieved into several class sizes, with the larger grain being the most desirable. As with wheat, planting date, fertilization, pest and weed control, timely harvesting and correct adjustment of the harvester are all of critical importance in producing grain of high quality.
It is important to be able to recognise the different cereals when they are growing, particularly the small grain cereals. With practice you can tell one crop from another by leaf colour and general appearance, but as a check, examine the young plants and look at the auricles which are the small claws at the point where the leaf blade meets the stalk of the plant. As one can see from the figure below, wheat has small hairs on the auricle, barley has big, bare auricles, and oats have no auricles.
Figure 1: The difference between Wheat, Barley and Oats
2. CULTIVARS
The farmer must decide on the end market for his crop, either grain, grazing or animal feed.
Cultivars more suited for grazing and hay production have different characteristics to those suited for grain production. The main cultivars planted in South Africa are as follows:
- Overberg Grain/grazing
- Sederberg Grain/grazing
- Kompasberg Grain/grazing
- Heros Grain
- Witteberg Grazing
- Pallinup Grain
- Potoroo Grain
- SSH 491 Grain/hay
- SSH 405 Grain
- SSH 421 Grazing
- Drakensberg Grazing/silage
- Maluti Grazing
3. PLANTING
Oats germinate and grow best in a well-prepared seedbed. Under conventional tillage systems the land should be ploughed to a depth of 150 – 225 mm, disced and harrowed to produce a fine seedbed. Seed can be planted by using a seed drill at the rate of 60 – 100 kgs per hectare. The land is roiled after sowing. The target plant population is 250 plants/m².
For an irrigated crop, the seed can be sown at any time after the end of April.
Oats can be grown on a wide range of soil types, and it is a crop that will tolerate more acid soils than either wheat or barley.
Table 2: Oats tolerance of Acidic Soils
| pH (Calcium Chloride Scale) | |
| Oats | 4.6 – 5.5 |
| Wheat | 5.1 – 7.0 |
| Barley | 5.5 – 7.0 |
WEED CONTROL
Grasses are a major problem in oats, as with wheat, and herbicide availability is limited.
Pre-emergence grass herbicides are normally used and advice should be sought from a qualified consultant.
A species of oat called wild oats is a serious weed in cereal crops because it cannot be controlled by the use of herbicides, for the herbicide that kills the weed also kills the crop.
IRRIGATION
Irrigation scheduling should take into account the critical growth stages of the oat crop, namely; 5-leaf stage, early stem elongation, flag leaf stage, flowering and during grain filling.
Irrigation during the later growth stages tends to disrupt uniform ripening, thereby delaying harvesting.
4. FERTILIZATION
Nitrogen can be applied safely to a crop being grown for cutting green, but care must be taken when applying nitrogen to a crop being grown for harvesting as grain. Oats have very weak straw, and too much nitrogen can cause lodging in the crop, making harvesting a difficult operation and causing the loss of grain.
A general recommendation for grain production is 90 kgs N/ha, 25 kgs P/ha and 20 kgs K/ha for a yield potential of 4,5 tons/ha.
Crops that are being used for green forage or hay should be top dressed with 100 kgs/ha N initially and 25 – 50 kgs/ha of nitrogen after each cut or grazing.
5. PESTS AND DISEASES
When oats are grown as a winter crop, the only diseases likely to affect the crop are crown and stem rust and barley yellow dwarf virus.
These are fungal diseases that are spread by aphids. They cause orange-yellow markings on the leaves and stems of the plants. The only control is to use resistant varieties. These diseases will cause a drop in yield, but they will not cause great damage to the crop.
6. HARVESTING
Forage oats can be cut by hand or by the use of a mower, loaded onto a trailer and carried to the cattle. Cutting can take place every 4 – 5 weeks and the crop should be top dressed after each cut.
Crops grown for grain can be harvested by combine harvesters at a grain moisture content below 20%, but can only be safely stored at a grain moisture below 12,5%.
Oat straw is a useful food for cattle and sheep.
In the manufacture of oatmeal, the grain is screened to remove impurities and then heated to reduce the moisture content to about 21%. It is passed between revolving stones which remove the husk from the grain, and the grains are then ground into meal. Oats treated in this way will yield about 60% of oatmeal.
