Cultivation or Package of practise for Fodder Sorghum (Sorghum bicolor (L)) Moench

Botany-
Annual, erect, single stalked or tillering; leaves alternate, ligules short membranous, inflorescence a panicle, contracted or loose, spikelets in clusters of 2 or 3 one sessile and hermaphrodite and the other/(s) pedicelled staminate or sterile; stamens three; stigmas two; styles terminal; fruit is a caryopsis.

Growth Stages-
Sorghum has five distinct growth stages:

1. Seedling Stage- Germination takes place in 4-5DAS. Emergence of coleoptiles indicates seedling stage.

2. Flag Leaf Stage-3-4 leaves with fully expended leaf area. Stage reaches in 40-55 DAS.

3. Boot Stage-Ear head covered within sheath i.e. under flag leaf stage reaches in 45-60 DAS.

4. Soft Dough-Endosperm filled with watery fluid. It’s called milky stage. Stage reaches in 70-85DAS.

5. Physiological Maturity- Grain with maximum accumulation of dry matter. Stage reaches in 85-95DAS.

Climate:-
It is a plant of warm climate. It remains dormant under unfavorable conditions, leaves posses waxy coating and presence of motor cells in leaves rolls the leaves under moisture deficit conditions. It is also posses more no of secondary roots/ unit of primary roots. Thus crop can withstand drought better than maize. Crop is grown in areas receiving 800-1000mm annual rainfall isohyets. High rainfall is undesirable though crop can withstand water logging. It is a Short day plant and a 10 hr photoperiod enhances early flowering. Increase in day length delay flowering and benefit dry matter production. During drought the cyanide content remains high.

Minimum temperature required for germination 7-10 degree C
Optimum temperature for growth 25-30 degree C

Soil Requirement-
The crop grows on every type of soil except very sandy soil. It is predominantly grown in vertisols. As a rainfed crop it is better suited to heavier soils retentive of moisture. It grows best in deep alluvial soils with irrigation. Black cotton soils of central India are considered as best soils for its cultivation. It can withstand moderate salinity.

Field Preparation-
Sorghum is a shallow rooted crop and does not require deep cultivation. 2 to 4 operations by desi plough or blade harrow, alternatively 2 to 4 times harrowing to pulverize the soil to a fine tith OR deep summer ploughing with mould board plough and two ploughings by country plough with the onset of monsoon are enough to prepare the land for sowing. Crop is grown in pH range of 7 to 8.5.

Manures & Fertilizers
The application of FYM @ 10 t/ha for drylands and 25 t/ha in irrigated areas plus 50 Kg Ammonium Sulphate at the time of planting and remaining 50 Kg at knee height stage (30-35 DAS) proves beneficial (Top dressing only when moisture is adequate). Nitrogenous fertilizers increased forage yields significantly. Forage yield is good when N coupled with P and K is supplied. Hence fertilization with balanced N, P & K is very important.
In irrigated are 100:80:50 Kg NPK/ha is applied. Source of fertilizer’s are urea, SSP & MOP. For multicut varieties 75-100 Kg urea along with 20 Kg P2O5 and 20 Kg MOP is applied after every cut.
Under dry farming conditions 50:40-80:40 Kg NPK/ha is applied. Instead of fertilizer dressing, 15 to 20 kg urea dissolved in 750 to 1000 lts of water may be sprayed every fortnight after establishment of crop for quick utilization of fertilizers and better succulence of crop. Care is taken not to apply excess of N fertilizers for free accumulation of nitrates.
In case of Zinc deficiency apply 10-15 kg of ZnSO4 or 0.2 % ZnSO4 with half quantity of lime to prevent burning of leaves. Iron chlorosis is a common problem is sorghum as it is very sensitive to iron deficiency. Spraying ferrous sulphate with lime is efficient to overcome deficiency.

Bio Fertilizers- Seed inoculation with Azospirillum brasilense.

Sowing Time-
Sorghum can be grown in Kharif (June-September), Maghi (late Kharif) September - December), Rabi (October-January) and in summer (January - May). Summer crops can be multicut in nature. Sowing of seed crop is so adjusted that it flowers at a time when there is no rains.

Seed Rate-
Since close spacing is necessary seed rate is usually higher 20-25 kg/ha for bold seeded varieties & 10-15 kg/ha small seeded varieties. Sometimes more than 100 kg/ha seed rate is used for producing thin stalked stems for hay making or to feed it without chaffing. In mixtures 25 kg sorghum and 20 Kg of cowpea or guar seeds/ha may be sown either in crosswise lines or 2 lines of sorghum alternated with 2 lines of legumes.

Spacing- For fodder crop spacing is kept Row to row: 25 to 30cm &Plant to plant: 10 to 15 cm.

Plant population-3.33 lakh plants /ha for fodders are considered optimum while for grain sorghum a plant population of 1.5-2.0 lakh plants /ha is considered optimum.

Method of Sowing-
Generally seeds are sown by broadcasting and covered with desi plough or harrow to achieve quick sowing in accordance with monsoon. The seeds must not be sown at 2-5cm depth. If germination is gappy seedlings from thick patches can be uprooted and transplanted in the evening.

Irrigation-
Sorghum is drought tolerant. An irrigated fodder crop of sorghum needs about 50 to 70cm of water in 5 to 7 irrigations. In hot and dry summers the crop requires irrigation every fortnight, but during rains excess water should be drained out of the field. During the post monsoon season irrigation water may be required every 3 weeks. Early seedling stage and flower primordial stages are considered most critical for moisture stress. Depth of irrigation is generally 6-8cm and water requirement of crop is around 80-480mm. Crop should be irrigated after each cut for better regeneration.

Cutting Management-
At the flowering stage the herbage contains low to moderate amounts of HCN. In young herbage, the HCN content may be as high as 750 ppm or more which is dangerous to animals. The plants at heading stage can be safely grazed or fed. So harvesting is to be done after 50 % flowering. After this stage crude protein content, digestibility, Ca & P content decreases sharply however crude fibre content increases. The stems become hard and woody with maturity. In multicut varieties, the first cut is taken after 2 months and subsequent cuts after 35 to 40 days. A long duration variety cut 2 to 3 times at 15 cm, better yields of quality forage then cut once at flowering. Crop should be cut 5-8 cm above the ground level for fast sprouting.

Sorghum Poisoning-
Young sorghum plants (30-40 days old) contain poisonous chemical cynogenic glucoside ‘Dhurrin’. ‘Dhurrin’ in the stomach of animals is converted to hydrocyanic acid. Thus when cattle, sheep and goats graze such green and growing sorghum crop (about 5 Kg) may result in hydrocyanic acid (HCN) or Prussic acid poisoning leading to carcinogenic death of animal. HCN content is more in leaves. Concentration of HCN is more in morning and in summers. Danger of HCN poisoning is greatest at immature stages of sorghum growth and decreases with maturity. The toxic limit of HCN is 200ppm, concentration decreases after 50 days. Hay and silage are generally free from HCN.HCN levels are most potent in:
young plants under 6 weeks old;
young regrowth;
plants stressed due to drought;
high soil nitrogen level;
Imbalance between soil nitrogen and phosphorus.

Generally, cutting the plants and chopping, and sun-curing can reduce HCN levels, because the HCN can evaporate with the loss in forage moisture.
Management to reduce HCN poisoning:
Do not turn hungry livestock out on lush regrowth of sorghum. Feed some dry fodder first, then turn out in the afternoon;
Do not graze until the regrowth is 18 to 24 inches tall;
Drying or ensiling or allowing the forage to mature will reduce its HCN content.

Sorghum or Yellow Effect or Soil Sickness-
The nutrient status of soil is exhausted by growing sorghum. The crop residue of sorghum having wide C: N ratio takes a long time to decompose. During this process of decomposition, part of soil nitrogen is temporarily immobilized affecting the succeeding crop. Such effect is more pronounced in low fertile soil causing to temporary deficiency of nitrogen in the soil for succeeding crop. To reduce sorghum effect, 25% more nitrogen is applied at the time of first fertilizer dose of the succeeding crop. It hastens the process of decomposition and overcomes the immobilized nitrogen. Ragi is the exception because its residue decomposes rapidly resulting in mineralization of soil nitrogen.

Weeds & Weed Control-
Sorghum is badly infested with grassy and broad leaf weeds because of congenial weather. 15-45 DAS of crop growth is critical period of crop weed competition. Sorghum halepense barru mimics with sorghum particularly before appearance of inflorescence.Inter row weeds can be controlled mechanically by running blade harrow, but intra row weeds remain.Striga (Striga lutea) causes 15-100 % loss depending on severity of infestation.

Constraints of Production-
Lack of demand for human consumption, non availability of improved seeds, cultivation of crop on poor soils and low acerage under HYV. Poor emphasis on plant protection and moisture stress are other factors leading to poor yields.