Barley

1.  INTRODUCTION

Barley has been grown from time immemorial, and is believed to be derived from wild grasses indigenous to northern Africa and western Asia.  It is widely grown in all subtropical and temperate countries. It is used for human food and in some parts of Europe it is used to make bread.  An interesting feature in the composition of barley is the nature of the protein in the grain.  This is quite different from the gluten in wheat.  When barley grains are boiled in water, the protein is dissolved in the water, and this extract is known as barley water which can be used as a protein food for invalids and young children.

Barley and its by-products are an excellent stock feed for all kinds of stock and, because of the thin husk and low fibre content, the grain is very suitable for feeding to pigs.  In the U.K., barley forms the basis of all livestock rations as maize does in Southern Africa.  The grain is very hard and should be rolled or crushed for feeding to cattle and sheep, and ground into meal for pigs and poultry.  The straw is of poor feeding value, but, being soft, it makes good bedding.

In most parts of the world where barley is grown, the best quality grain is used for the brewing of beer, and this grain is called Malting Barley.  It is particularly suitable for brewing because of the high starch content of the grain, and because of the enzymes produced during germination.  In South Africa, barley is grown only for malting, and the only markets for the crop are brewing companies such as South African Breweries (SAB). After wheat production, barley is the second most important small grain crop in South Africa.  Barley is grown as a Winter crop in the Southern Cape dryland or irrigated in the Northern Cape under full irrigation.  All barley is grown under contract to the breweries.  Farmers wishing to grow malting barley should contact National Breweries, and if they are accepted as growers, they will be given a grower’s registered number and a contract to grow a certain area of barley.  Seed is obtained from the South African Barley Breeders Institute (SABBI) which was established in 2001 by SAB.

QUALITY OF MALTING BARLEY

The quality of barley used for malting must be good, and is judged on the following points:

• The grain should be plump, well filled with a fine, wrinkled skin.

• Each grain should contain the maximum amount of starch, and when the grain is cut in half, the centre should be ‘mealy’ with a white colour and a floury texture.  When poor quality grains are cut in half, they show a bluish colour and appear to be extremely hard.  This condition is called ‘steely’, and is caused by too little starch and too much nitrogen or protein in the grain.

• The nitrogen content of the grain is most important and should not be higher than 1.6% which is equivalent to a crude protein content of 10%. Nitrogen content higher than this spoils the sample for malting.  This is exactly the opposite to a sample of wheat for milling.  Therefore, higher nitrogen content and a ‘steely’ grain sample are desirable.

• The colour of the grain is important because dark coloured grain can be used only for the production of dark beers and stout.  Pale-coloured type beer called a lager requires a light-coloured barley grain.

• The sample of grain should not contain any damaged, chipped or cracked grains because these will go mouldy during the process of malting and will spoil the quality of the malt.  As all barley is harvested by combine, it is essential to check the drum setting on the combine so that no grains are damaged.

• During the process of malting, the grains are germinated and this must be done evenly, with all the grains germinating at the same time.  In order to achieve this, the grains in the sample must all be of the same size and, above all, the same variety.  Two or more different varieties in a sample will completely spoil the sample for malting.

• Any heating of the grain during storage, or any weathering will spoil the colour and the smell of the sample.

2.  VARIETIES

Barley varieties in South Africa have been bred or recommended by SABBI. For Barley production in the Southern Cape, the following varieties are recommended;

• SSG 564
• SabbiErica
• SabbiNemesia
• S5

The following two varieties have been bred or recommended by SABBI for the irrigated areas of South Africa.

• Cocktail
• Puma

The malting characteristics of the varieties above differ in terms of their dormancy which in malting barley terms is the period from harvesting to the stage where the barley is germinated for malting. For this reason mixing of these varieties is not at all advisable. It is imperative that the different varieties are transported, handled and stored separately.

The average time to maturity for these varieties is similar to the maturity time for wheat.  It varies from 125 to 150 days according to the growing area.

The flower or spikelets of the fruiting head are arranged alternately on opposite sides of the stem at the nodes.  Each node produces three flowers, and, in the 6-row variety, each of these spikelets produce a grain; they are all fertile.  In the 2-row variety, only the centre spikelet produces a grain.  The ones on either side produce stamens only.  In the U.K. most of the varieties grown are 2-row, but in other areas the common variety is a 6-row variety.

Figure 1: The flower arrangement of barley

Plant breeders at SABBI are continually testing new varieties, and the factors they test for in malting barley are:

• Uniformity of grain size.
• Resistance to lodging by means of shorter stiffer straw.
• Higher yields.
• Higher Brewer’s Extract.
• Resistance to disease.
• Higher tillering capacity which produces more fruiting heads per plant.

3.  PLANTING

Barley is a shallow-rooted crop and gives the best results when planted in a rich loam soil.  Like Winter wheat, it does well in a rotation with soya beans.  Land should be ploughed to a depth of 230 mm, and care taken to cover all the trash from the previous crop.  Disking and harrowing should produce a firm seedbed with a fine tilth.  This is because barley seed is fairly small and even germination of the crop is essential. The initial dressing of compound fertiliser should be broadcast onto the seedbed and disked in as deeply as possible.

Barley is a crop which prefers lime and does not do well on acid soils.  The soil pH should be within the range 5.5 to 6.0 and lime should be applied to the seedbed if required.

TIME OF PLANTING

The crop in the dryland areas of the Southern Cape should be planted between the end of April and the end of May, and should be ready for harvesting in September. However for the irrigated regions of South Africa, planting takes place from the start of June to the first week of July.

It has been proven that earlier plantings within the planting period have a higher yield potential. Earlier planting as well as a comprehensive pest and disease control programme will ensure higher yield. Farmers take a greater risk in yield when they plant late.

Seed can be sown by the use of a seed drill or it can be broadcast by means of a Vicon fertiliser spreader.  The seed drill is by far the best method because it uses less seed, gives an even germination of the seed, more uniform growth of the crop and a higher yield.  Uniform ripening is an important factor in the growing of malting barley.

PLANTING RATE

This is 65 kgs per hectare if a seed drill is used. The average recommended planting density is 80 kgs per hectare. The aim is to get to approximately 130 to 170 plants per metre squared at harvesting. This will contribute to the heads per metre.

Seed should be planted 35 mm deep into a seedbed that is well watered but not waterlogged.  An even distribution of moisture is essential to ensure even germination.

Planting rate should also always compensate for lower germination capacity of some seed, poor emergence, damping off of seedlings and the planting method used.

WEED CONTROL

Control of weeds is of vital importance for the barley crop as it is very sensitive to weed competition especially in the early development stages of the crop. Early weed control will enhance the potential yield gained from the crop and should be done as soon as possible after weeds have germinated.

As barley is sown either in drills, which are close together or it is broadcast, mechanical weed control is not possible once the crop has been planted. Cultivation of the seedbed before planting will help kill weeds that have just germinated, but later weed control must be by means of an herbicide which is sprayed onto the crop. Weeds must be correctly identified as either broadleaf or grass weeds as different herbicides will be used. The recommended herbicides for the control of grass weeds in barley are Hoelon, Ravenger and Grasp. The correct amount of herbicide is recommended on the label and must be applied correctly as too high a dosage will negatively affect the barley. 

Wild oats can be a serious nuisance to barley, because these will spoil the sample for malting.  The herbicide affects only broad-leaved weeds and will not kill wild oats.  Any wild oat plants should be removed from the crop by hand.

IRRIGATION

Barley is irrigated in other growing areas of South Africa such as on the Vaal and Orange Rivers. But irrigation is not required in the Southern Cape which has a winter rainfall pattern.

In general, the irrigation of the barley crop is the same as that for wheat.  Flood irrigation is still used but overhead spray irrigation such as centre pivots and sprinklers are more efficient.  The seedbed should be brought up to field capacity at planting.  The critical times when water stress should be avoided are the rooting stage, the flowering stage, and the grain-filling stage.  A lack of water at any of these stages will reduce the yield of the crop, and may lead to high nitrogen content in the grain and also small grain size. However if lodging is a problem especially regarding the older varieties it can be minimised if the crop is over irrigated during the early growth stages and applying less water in the 10 to 14 weeks after planting date. At this stage water stress will have the least yield effect on the plant. At the booting stage, which is the point at which the flowering heads are just about to appear, the frequency and amounts of irrigation should be as follows:

	Sandy Soils	Clay Soils
Frequency	Every 8 – 10 days	Every 12 – 15 days
Amount	30 – 38 mm	46 – 64 mm

As the plant matures, the amount of water applied should be increased and should be about 40% more than the figures shown above by the soft dough stage.  The final irrigation should be given when at least half of the crop has reached the yellow-stalk stage.

When the crop is being planned, the size of the crop to be grown should be based on an irrigation frequency of 7 – 8 days on sandy soils, and 10 – 12 days on heavy soils, and the amount of water applied should be equal to 5 mm per day.  Over the growing period of the crop, this gives a total of 625 mm.