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Sorghum

Sorghum is a food, fodder and technical crop.

Economic importance

Sorghum, as an agricultural crop, is of interest in arid regions. Under these conditions, its yield is superior to corn and spring barley. According to the data of variety plots of the North Caucasus for many years of observation, grain yield of sorghum was 2.93 t/ha, corn – 2.5 t/ha, spring barley – 1.98 t/ha.

Sorghum has several uses: grain for animal fodder, raw material for the production of compound feeds, starch and alcohol industry, groats. In many regions of Africa, India, East and Central Asia, sorghum is the main bread plant.

As a food plant, sorghum ranks fifth in the world, behind wheat, rice, corn and barley.

Sorghum green matter is used as livestock feed or silage, which is of slightly inferior quality to corn. Good quality hay is obtained by mowing the stalks until they are coarsened. The sorghum can regrow after mowing and be used as green fodder or as pasture.

The fodder feature of sorghum is that the leaves and stems remain juicy when the grain is fully ripe.

100 kg of grain equals 119 fodder units, green matter equals 23.5 fodder units, silage equals 22 fodder units, and hay equals 49.2 fodder units. Grain contains up to 15% of protein rich in lysine, stalks of sugar varieties contain 10-15% of sugars, sap – 24%, which are used for the preparation of syrups.

Whiskers of broom sorghum are used to produce brooms and brushes. Sorghum may be used as a strip crop for snow retention, creating strips of high-stemmed plants to protect crops from wind erosion. Cultivation in stubble and hay crops is of interest.

History of crop

The place of origin of sorghum is considered to be equatorial Africa. The crop was known for 3 thousand years BC in India and China, for 2.5 thousand years BC in Central Asia.

In Russia sorghum was brought in the XVII century.

Cultivation areas and yields

Sorghum is grown in many countries around the world. In India the area of sowing is 16 million hectares, in the USA – 5.7 million hectares, in Africa – 15.4 million hectares. Large areas are sown in the Middle East, China, Romania, Bulgaria, Hungary, Italy, Australia, South America, Japan. Total sorghum sown area in the world in 1980 amounted to 47.7 million hectares or 7% of the area of grain crops, with an average yield of 1.42 t/ha. The gross harvest of grain was 75 million tons or 4% of the total grain harvest.

During the USSR, the sorghum sown area was about 150 thousand hectares mainly in Central Asia, in the south of Ukraine, Moldavia, the North Caucasus, Transcaucasia, the Lower Volga region and Kazakhstan. The average yield was about 1.5 t/ha.

In Russia, there is no statistical data on sorghum. It is supposed to sow an area of 20-30 thousand ha (25 thousand ha in 1997), and to harvest 25-35 thousand tons of grain, with an average yield of 1.2-1.4 t/ha of grain and 20-30 t/ha of green matter. The main sown areas are concentrated in the arid steppe of the Southern Federal District (North Caucasus and Lower Volga region).

In the steppe zone sorghum is capable of yielding stable grain yields of 2.5-3 t/ha and green matter yields of 20-30 t/ha.

On state harvesting plots, grain yield varied from 2.5 to 5.0 t/ha, green matter for silage from 20 to 30 t/ha, with irrigation 80-100 t/ha. In 1982, high yields were obtained in Rostov region (collective farm “Lenin’s Way”) – 2.12 t/ha on an area of 700 ha, in Zernogradsky area (collective farm “Litunova”) – 2.48 t/ha on an area of 200 ha.

Hybrid sorghum seeds showing high heterosis in the first generation are widely used.

In arid areas, hybrids with high productivity give higher yields than corn. According to the data of the Genic Experimental Station of the All-Union Research Institute of Corn, the Stepnoi 5 grain sorghum hybrid yielded on average 5.24 t/ha of grain for 8 years, which is 2.88 t/ha higher than the corn yield. At the Ribnita state variety site in Moldova, the average yield of this hybrid in 5 years was 7.81 t/ha, the hybrid of maize VIR 42 – 6.02 t/ha.

Botanical description

The Sorghum Moench (Pers.) genus is represented in Russia by cultivated species:

common sorghum – S. vulganense Pers., cultivated for fodder, technical and food purposes;
jughara – S. cernum Host. – with a curved inflorescence;
gaolian – S. chinense Jakuchev;
sudan grass – S. sudanense Pers., cultivated as a fodder plant.

Common sorghum has the greatest distribution in Russia.

Of the wild sorghum species, humai, a weed, is widespread in southern Russia.

Root system

The root system is fibrous, powerful, penetrating into the soil up to 2.5 m deep and 60-90 cm wide.

Aerial, or supporting, roots are formed from the above-ground nodes.

Stem

In different varieties, the stem height varies from 0.5 to 2.5 m, in tropical countries up to 7 m.

The stem is filled with loose parenchyma, often strongly branching.

The productive bushiness ranges from 1-2 to 5-8 stems per plant.

Leaves

Leaves are broad, covered with a waxy coating, with 10 to 25 leaves per plant.

Inflorescence

The inflorescence of sorghum is a panicle 15-60 cm long, with two spikelets at the ends of each branching. One spikelet is monoecious, the other is male and falls off after flowering. Up to 70% of flowers are pollinated by cross-pollination, while self-pollination is less common.

Grains are filmy or glabrous, without a furrow, rounded and egg-shaped, within spikelet and pedicel scales. Coloration is white, brown, yellow or brown. A single panicle may contain 1,500 to 3,500 seeds.

Seeds have a very short dormancy period, capable of swelling and germinating immediately after harvesting. Grains with a brownish or reddish color of the endosperm contain astringent tannin tannins, which is a disadvantage for fodder, while in alcohol and maltose production it is an advantage because these substances suppress rotting processes.

Subspecies

Depending on the shape of the panicles, sorghum is divided into:

  • branched or panicle-shaped (effusum Korn), which has a loose panicle and long branches;
  • contracted (contractum Korn) with a compressed short very dense panicle, upright or curved stem tip;
  • clumped (compactum).

The clumped sorghum is of primary importance in the crop.

Biological features

Temperature requirements

Of all cereals of group II, it is the most thermophilic plant; even slight and short-term frosts to -1 … -3 °C are destructive for seeds. The optimum temperature is 27-35 °C, and it withstands heat up to 40 °C.

Seeds germinate at 8-13 °C; optimum temperature is 18-20°C. The minimum average daily temperature for the start of flowering is 14-15 °C; the minimum daily temperature for ripening is 10-12 °C. The sum of active temperatures during the growing season is 2250-2500 °C.

Moisture requirements

Sorghum is considered the most drought-resistant field crop. Transpiration coefficient is 150-200. It tolerates heat well, with leaves continuing to assimilate when corn loses its turgor and curdles. Also tolerates soil and air drought.

In the first 30-40 days after sprouting, growth is slow and in drought the plants are able to “freeze”, with leaves curling, secondary roots not forming, and no growth.

Sorghum gives acceptable yields in the absence of irrigation on the semi-desert border. Plants use atmospheric precipitation in the second half of summer and early fall.

Light requirements

 The plant is light-loving and short-day.

Soil requirements

Sorghum does not require soils, tolerates salinity, heavy and very light soils.

Well warmed, loose, permeable, non-swampy soils are preferred.

It responds to the application of organic, nitrogen and phosphorus fertilizers.

Vegetation

Like all millet-type grains, grows slowly at first, does not tolerate weedy fields.

Growth phases:

  • sprouts in medium-ripening sorghum appear 10 to 15 days after sowing;
  • third leaf;
  • tillering phase 25-30 days after sowing;
  • emergence into a tube 40-50 days after sowing;
  • formation of panicles 55-65 days after sowing;
  • flowering – 5-6 days after weeding;
  • milky ripeness of grain;
  • waxy ripeness of grains;
  • full grain maturity.

The vegetation period of different early maturity varieties is 90-160 days.

Crop rotation

Sorghum is well tolerant to repeated sowing, so it can be grown on permanent plots if they have no cases of bacteriosis infestation. In the experiments of the All-Union Scientific Research Institute of Corn, the yield of sorghum when growing on a permanent plot for 10 years did not decrease and averaged 2.69 t/ha, in the crop rotation (fallow – winter crops – winter crops – sorghum) – 2.49 t/ha.

In the rotation, sorghum is placed after leguminous crops, winter crops, corn and other row crops. For example, in the steppe of Kabardino-Balkaria, the grain yield of sorghum after peas was 5.28 t/ha, after winter wheat – 4.95 t/ha, the silage mass yield was 44.6 and 38.5 t/ha, respectively.

Sorghum belongs to row crops, so it serves as a good predecessor for spring crops.

Fertilizer system

Sorghum is responsive to fertilization when grown for grain and silage. Fertilizer efficiency increases under irrigation conditions. Like other cereals, sorghum responds most strongly to nitrogen fertilizers and then to phosphorus fertilizers.

Thus, in the conditions of the steppe zone of Kabardino-Balkaria, different types of fertilizers on the background of irrigation gave the following results.

Table. Effect of fertilizers on sorghum silage yield under irrigation (steppe zone, Kabardino-Balkaria)

Experience option
Yield, t/ha
Yield increase
1965
1966
среднее
t/ha
%
Without fertilizer (control)
42,9
38,1
40,5
-
-
N60
53,4
46,2
49,2
8,7
21,6
P60
51,2
42,8
47,0
6,5
16,0
K60
45,0
39,6
42,3
1,8
4,5
N60P60K60
58,7
52,6
55,6
15,2
37,5
10 t/ha of manure + N45P45K45
63,4
61,6
62,5
22,0
54,4

The greatest return on the fertilizer is obtained by applying a full mineral fertilizer, as well as the joint application of organic and mineral fertilizers.

Basic fertilizer

On rainfed lands under autumn plowing 8-10 t/ha of manure, 200-300 kg/ha of superphosphate, 100-150 kg/ha of nitrogen fertilizer and 100 kg/ha of potassium.

Pre-sowing (row) fertilizer

Row fertilization at a rate of N10P10 at a distance of 4-5 cm away from the row and 2-3 cm deeper than the seed is also effective.

Tillage system

Autumn tillage for sorghum consists of stubble discing to a depth of 7-8 cm and deep autumn tillage to a depth of 25-27 cm. Such tillage provides a 37-50% reduction of weediness of fields and an increase of moisture reserves by 25%. According to the Poltava Agricultural Experimental Station, such tillage increases the yield of green mass by 22-25%. According to the data of the Volgograd Agricultural Experimental Station, grain yield increases from 1.98 t/ha to 2.51 t/ha compared with plowing at the depth of 18-20 cm.

Harrowing is done in early spring, followed by 2-3 pre-sowing tillage: the first – to a depth of 10-12 cm, the next – to a depth of 5-6 cm. Under conditions of insufficient moisture after the first cultivation the soil is rolled to provoke weeds germination and their elimination by the subsequent pre-sowing cultivation. In very dry spring, the soil is also rolled before sowing.

Seeding

Preparation of seeds

Preparation of seeds for sowing consists of sorting, air-heat treatment and treatment with fenthiuram at the rate of 200 g per 100 kg of seeds.

Timing of seeding

Sowing is started when the soil warms up to 12-15°C at the seed embedding depth (3-5 cm). According to the research of Zernograd Breeding Station (N.T. Gaiko), it was noted that varieties and hybrids resistant to low temperatures during the initial growth period, such as Efremovskoe red 8 and Don 22 hybrid, give greater yields when sown into the soil heated to 12 °C.

Varieties more sensitive to low temperatures are sown at soil temperatures of 16-18 °C.

Table. Yields of green mass and grain of sorghum depending on sowing dates (1968-1970).

Sowing date
Soil temperature at the seed placement depth, °С
Sugar sorghum yield, t/ha
Grain sorghum yield, 100 kg/ha
Kuban Yantar
Zernogradskoe 3
Don 22 Hybrid
Efremovskoye Krasnoye 8
Zernogradskoe 25
I
8-9
17,7
23,3
22,5
22,1
11,4
III
11-13
19,3
25,0
29,5
30,9
23,5
V
16-18
16,1
23,8
20,6
17,8
35,2
VI
18-20
16,6
21,5
10,3
10,1
31,6

Methods of seeding

The method of sowing sorghum – dotted, seeders СТСН-6 with a row spacing of 60-70 cm and the distance in the row 15-20 cm.

When sowing on the grain the square-nest method of sowing on the scheme 70×70 cm and 90×60 cm is used. In the nest sow 4-6 seeds. Plant density in the temperate zone is 60-160 thousand/ha, in arid conditions – 40-50 thousand/ha.

If cultivated for green fodder and hay it is optimal to use the double row sowing with the scheme 45×15 cm or 60×15 cm with an ordinary grain seeder, and also through-row sowing (30 cm).

Seeding rates

Seed rate for the dotted method is 10-14 kg/ha, for the square-nest method – 6-10 kg/ha, for the row and double row method – 20-25 kg/ha.

Seed sowing depth

The sowing depth is 3-5 cm.

In dry weather and on light soils – 6-8 cm.

Mixed crops

Sorghum is used in mixed crops, primarily with leguminous crops – soybeans, chickpeas, beans, vetch, etc. in alternating rows. The yield increases by 15-20% compared to the yield of sorghum alone, and the fodder quality of the mixture is higher.

Legumes are sown in separate rows between the rows of sorghum or in a cross direction by 50-80 kg/ha.

Mixed crops of corn for silage and sorghum are also used, which increases the yield of green mass by 3-5 t/ha and lengthens the silage period by 10-15 days. According to the Erastovsky experimental station (Dnepropetrovsk region, Ukraine), sowing one row of corn gave 13.5 t/ha of green mass, the joint sowing of two rows of corn and one row of sorghum – 16.0 t/ha.

Mixed crops of corn, soybean, and sorghum for silage also give good results.

Crop care

After sowing, the soil is rolled with toothed or ring rollers. When soil crust is formed or weeds appear, perform pre-seeding and post-seeding harrowing (in the phase of 3-4 leaves) across the rows. Harrowing gives good results with dense crops and well-rooted plants, otherwise rotary hoes such as МВ-2,1 are used.

When 6-7 leaves are formed, the third harrowing may be carried out, which allows to kill up to 70% of weeds.

As the soil compacts and weeds grow, carry out 2-3 inter-row treatments.

To control weeds, spraying with herbicides of 2,4-D group or others in the phase of 3-6 leaves is carried out. Propazine is used after sowing until emergence of seedlings at a rate of 3-6 kg/ha.

In sorghum crops apply herbicide Agritox (500 g/l) against annual dicotyledons; spraying in tillering phase before emergence of a tube.

Harvesting

Grain sorghum is practically not subject to shattering, so it can be harvested in the phase of full grain ripeness by harvesters with a reduced number of drum rotations – up to 500-600 per minute. If the humidity of the grain is more than 20% it is necessary to use the sorghum-harvester СМ-2,6 or a retrofitted grain harvester.

The sugar sorghum crop is harvested at the end of the waxy ripeness phase on a low cut.

The panicles of broom sorghum are usually cut by hand at the beginning of full grain ripeness, but the panicle branches must remain green. The stalks are then mowed with harvesting machines, such as mowers or reapers, and can be used for silage. The grains are removed from the clusters by combing them.

For silage, sorghum is harvested at the end of milky ripeness and the beginning of waxy ripeness before the lower leaves dry out and fall off.

For green fodder and hay, sorghum is harvested until the stem coarsens, and no later than at the beginning of heading. After harvesting, sorghum thrives and produces green manure, but poisonous hydrocyanic acid may accumulate in the young plants and in the hydrolysis of duprin glucoside. Its content may vary from 0.003 to 0.31%, a toxic content of more than 0.1% is considered. As the plant ages, the hydrocyanic acid content decreases sharply, while the sugar content increases. In the cut pulp after 2 hours of drying the hydrocyanic acid is destroyed.

Progressive cultivation technology

Technology of sorghum seed production in Rostov region (specialized state farm “Manychsky”). Yield 1.6-2.0 t/ha (1979-1982), sown area up to 2 thousand hectares. The cost of 100 kg of sorghum seeds in 1982 was 484 rubles, the net profit from the sale of seeds – 634 thousand rubles.

The forecrop was leguminous crops, maize for silage, and winter wheat. Tillage included removing stubble to a depth of 5-7 cm after the previous crop harvesting, repeatedly – after weeds regrowth. Plowing to a depth of 27-30 cm with the application of 60 kg/ha of nitrogen and 90 kg/ha of phosphorus.

Cultivation was carried out in spring. Seed preparation included air-heat treatment for 4-5 days and treatment with film-forming preparation. Seeding method was wide-row with row spacing of 70 cm. Seeding rate for early maturing varieties – 300-400 thousand/ha of germinated seeds, late maturing varieties – 150-180 thousand/ha.

Care consisted of harrowing in 4-5 days after sowing until emergence, then cultivation КРН-4,2: the first – after emergence, the second – simultaneously with the fertilization of liquid mineral fertilizers, the third – hilling. In the phase of 3-4 leaves we treated with herbicide amine salt 2,4-D at a dose of 0.6-0.8 kg/ha a.d.

Harvesting was carried out by a single-phase re-equipped combine “Niva”. When grain moisture exceeds 20%, harvesting was two-phase, mowing was carried out by the harvester ЖВН-6, threshing – combine with picker ГГПТ-3,0.

The sorghum seeds of silage varieties were harvested in two phases by a sorghum-harvesting machine.

Groups and varieties

According to the economic purpose, E.S. Yakushevsky proposed to subdivide sorghum into: grain, sugar, broom, and grass sorghum.

All types of sorghum are easily crossed, the first generation of hybrids is characterized by high productivity as a result of heterosis. Sorghum-sudank hybrids and hybrids of jugara with broom sorghum have an important economic value.

Grain sorghum

Grain sorghum is a relatively stunted, weakly bushy plant with an open, easily flaked grain; the stem core is semi-dry. The tannin content is 0.034-0.34%. Grains of food varieties are white, tannin is absent. The main area of use – food and fodder.

Hybrid Steppe 5. Zoned in the south of Ukraine.

Variety Kubanskoe krasnoe 1677. Zoned in Krasnodar Krai and Volgograd region.

Sugar sorghum

Sugar sorghum is used for green fodder, making silage, and from the stems for sweet syrup and molasses. The plant is taller, more bushy and has succulent stems. The raw stem sugar content is up to 15%, the stem juice up to 24%. Kernels are filmy or semi-filmy, with a poor flaking texture. The maximum sugar content is reached in the phase of full ripeness of grain.

Variety Ranniy Yantar Dnepropetrovskii. It is zoned in the Central Black Earth zone, the North Caucasus, the Volga region, as well as in Ukraine and East Kazakhstan region.

Variety Krasniy Yantar. It is released in the North Caucasus, Khabarovsk Territory, Crimea, Kalmykia, as well as Moldova and Tajikistan.

Broom sorghum

The broom sorghum is characterized by the dry core of the stem. The length of the panicle is 40-90 cm, the main axis is absent or shortened. The yield of panicles is 1.5-2.0 t/ha, the yield is 2-4 thousand panicles per hectare. Grain is filmy, hard to peel.

Not suitable for fodder purposes because of its dry heart. The quality brooms are considered thin, long, flexible, even, bright green, 35-50 cm long, with reddish stain.

Variety Venichnoe 623. Zoned in the Rostov region, Stavropol Territory, as well as the south of Ukraine.

Variety Veninochnoe early. It was released in Voronezh Region, Khabarovsk Territory, and Dnepropetrovsk Region of Ukraine.

Grass sorghum

Grass sorghum, or Sudan grass, is characterized by a large bushiness, thin stems and rapid growth. It is mainly cultivated for hay and green fodder.

Sources

Crop production / P.P. Vavilov, V.V. Gritsenko, V.S. Kuznetsov and others; Ed. P.P. Vavilov. – 5th ed., revised. and additional – M.: Agropromizdat, 1986. – 512 p.: ill. – (Textbook and textbooks for higher educational institutions).

V.V. Kolomeichenko. Crop production / Textbook. — M.: Agrobusinesscenter, 2007. — 600 p. ISBN 978-5-902792-11-6.

Fundamentals of agricultural production technology. Agriculture and crop production. Ed. V.S. Niklyaev. – M .: “Epic”, 2000. – 555 p.