OAT PRODUCTION IN THE SUMMER RAINFALL REGION
Oats has been cultivated in the past mainly for grazing purposes and hay production. Grain production of oats makes a limited contribution to the developing breakfast cereal market, with the majority of grain produced ending up in the animal feed market. Human consumption of oats is currently the only organized market, with competitive grain prices being paid for a product with suitable grain quality. There are however other attributes of oats that are of importance. The introduction and expansion of no-till practices and reduced cultivation systems necessitates the use of suitable cover crops to achieve significant ground cover. Oats is suited to this scenario due to the wide planting spectrum, wide adaptability and high biomass production, and can be planted with available cultivation equipment. Furthermore, oats has a depressing effect on soil-borne diseases, like take-all, in these crop rotation systems.
Grazing, silage and hay production
Oat grain is widely used by horse owners and other producers in feed mixtures. Well fertilized oats produces high quality hay and grain with a high nutritional value. Oat grain that do not qualify for suitable grades due to low hectolitre mass values, is also utilized in the animal feed market. Oats plays a significant part in a balanced grazing availability program, with several cultivars suited for this purpose. The wide adaptability, nutritional value and regrowth characteristics of oats create the situation of available grazing over a long period. Planting for this purpose can start in February and continue up to July.
For hay production under irrigation, the cultivar SWK001 and SSH 423 can be planted from March to June at a seeding density of 40 - 50 kg seed/ha. SSH 421, SSH 405 and SSH 491 can be planted from May to June at a seeding density of 70 - 100 kg seed/ha.
The local consumption of oats for processing in the cereal market is approximately 40 000 - 50 000 ton. Due to the low quality of oats grain produced (mainly of a low hectolitre mass), a major part of this local grain production is not suited for commercial processing and the requirement of the market is filled via imports.
Local cultivars have the potential to produce the required yield and quality oats.
The quality standards applied at present are directly related to the processing of the oats seed. To develop an understanding of these standards it is necessary to briefly note the most important processes through which oats goes during processing.
Firstly all impurities and foreign material such as chaff, stones, weed seeds, wheat and barley are removed. The groats or kernel is the economically valuable part of the grain, while the hulls have no commercial value. The hulls are removed by two rotating milling stones that are set fractionally closer to one another than the
thickness of the grain, and literally rub off the hulls. It is thus understandable that the hulls of twin oats cannot be removed and that naked oats will be damaged in this process. After this process the oats undergoes specific processing for the purpose for which it is needed.
Large and well filled groats/kernels are in big demand by the processors and hectolitre mass is an indication of this quality aspect. The minimum hectolitre mass depending on the grade is shown in Table 1. Just as in the case of wheat and barley, hectolitre mass of oats is determined during the grain filling stage. Abnormal leaf senescence prior to or during flowering and grain filling due to malnutrition, diseases or stress, causes low hectolitre mass. The deficiencies must be corrected before the flag leaf stage to ensure a positive effect on hectolitre mass.
Table 1. Grading requirements for oats
Grade Minimum hectolitre mass (kg/hl)
Grade 1 53
Grade 2 48
Feed Grade 38
The oats kernel is enclosed by two hulls that are worthless to the industry. Plenty of groats and little hull are thus required and processors require no more than 30% hulls against 70% or more groats. This characteristic is generally also reflected in the hectolitre mass and is environmentally, as well as genetically determined.
In shrivelled oat grain the hulls make out a greater percentage of the groats:hull relation and in this case is undesirable.
During processing the oats grain is sieved into different class sizes. This process is done very accurately, as an important quality component of the end-product relies on the effectivity of the sieving process. The largest seeds are more desirable, while the smallest grains are generally worthless. Uniform seed size is thus ideal.
As the largest seeds ripen first and tend to fall out first, it is important not to delay harvesting. Twin oat grain often occur. This characteristic is cultivar specific but can also be the result of environmental conditions and the harvesting process. Twin oats are undesirable as they go through the sieving process as large seeds and are later separated as two small oat grains that later cannot be dehulled. The harvester must thus be set in such a way that a minimum of twin oat grains are harvested. Naked oat grains are grain of which the hulls have been removed in the harvesting process and are totally undesirable as they are separated into the small and medium seed sizes in the sieving process and are then ground, not dehulled in the dehulling process. The adjustment of the harvester is thus critical and requires special and specific attention by the producer.
As with wheat, planting date, fertilisation, pest and weed control, timely harvesting and correct adjustment of the harvester is of critical importance to produce grain of high quality. Locally available oats cultivars do have the potential to produce suitable quality grain and this potential must be utilized. General production practices for oats in the summer rainfall area are similar to that for wheat production.
Irrespective of the crop rotation system followed, the main aim is to accumulate the maximum amount of soil water, alleviate compacted soil layers and prepare a seedbed that will ensure good germination and seedling establishment. Planting activities of oats are similar to those of wheat with regard to planting depth and row widths used.
Seed treatments for oats
The standard seed treatments against seed-borne diseases must be applied in grain productions, while it is optional in grazing and hay productions.
Cultivar choice, planting spectrum and seeding density
The producer must decide on the end-market for the production, that being grain, grazing or feed (Table 2). Cultivars more suited for grazing and hay production have different characteristics, and a cultivar for grain production must be chosen in correspondence with the needs of the buyer and end-user of the product, but also fits into the production system of the farmer. Once this decision has been made, plant the chosen cultivar and optimise all production practices (Tables 3, 4 and 5). Use certified seed to ensure that the correct cultivar is planted according to the proposed end-user, and to ensure good germination and seedling establishment.