Sorghum cultivation
Dear farmers,
Sorghum is a major food grain crop in the world. It is a staple food for humans. It is also used as parched and popped grain. It serves as an important source of cattle feed and fodder. The grains are fed to cattle, poultry and swine. Sorghum grain contains 10-12% of protein, 3% fat and 70% carbohydrates.
Growth stages
1. Seedling stage
Germination takes place in 4-5 days after sowing. The emergence of coleoptile indicates seedling stage.
2. Flag leaf stage
3-4 leaves with fully expanded leaf area (40-45 DAS).
3. Boot stage
Ear head covered with sheath i.e. under flag leaf (45-60 DAS).
4. Soft dough
Endosperm filled with watery fluid. It is called milky stage (70-85 DAS).
5. Hard dough
Three fourth of grain weight accumulated, grain contents relatively solid.
6. Physiological maturity
Maximum dry weight of grain and plant attained (85-95 DAS).
Climatic requirements
Sorghum requires warm climate, but can be grown under a wide range of climatic conditions. In temperate region, it is grown during summer, however in the tropics it is sown throughout the year . It needs about 26-30°C temperature for its optimum growth. The minimum temperature for germination is 7-10°C. However, the yield is adversely affected when the mean temperature exceeds 26°C during heading period. It is well adapted to semiarid regions with a minimum annual precipitation 350-400 mm as well as rainfall ranging from 400-1000 mm. It can tolerate drought conditions very well as it remains dormant during moisture stress. It can also tolerate waterlogging. Sorghum at the boot leaf stage is very sensitive to temperature, but less sensitive to soil stress than during flowering.
Soil
Sorghum is grown on a wide range of soils, but medium to deep soils having good water retention capacity are best suited for growing sorghum. It may tolerate mild acidity to mild salinity and can grow with wide a range of soil pH (5.5 to 8.5). The black cotton soils of central India are very good for cultivation of sorghum.
Land preparation
Deep ploughing to a depth of 20-25 cm with mould board plough soon after Rabi crop and keeping soil exposed to the sun until the onset of monsoon is a common practice. Then, it should be followed by 2-3 harrowings. If necessary planking should be done to break the clods and to level the field. Stubbles and other plant remains should be collected and removed from the field.
Seed rate and spacing
Seed rate largely depends on the type of cultivar, duration and the purpose for which it is grown. Old varieties require less seed rate than hybrid sorghum. Seed rate of 8-10 kg/ha found optimum for varieties and 10-12 kg/ha for hybrids. Seeds should not be not be sown more than 5 cm deep. The sowing depth should be 3-4 cm.
Sowing method
The crop is sown either by broadcasting or by drilling the seeds behind the plough. Seeds of hybrids and varieties always be sown in rows for getting maximum yield. Sorghum is a tall growing crop and shading cannot be avoided. The sowing is therefore done at sunrise and sunset direction. It does not cast shadows over the plant of the same row or on the side of the row.
Seed treatment
Seed treatment with Thiram or Agrosan G. N. @ 3 g per kg seed is necessary to protect the crop from fungal diseases like grain smut. Always use certified seed and should be purchased from the reliable source such seed is always treated with.
Manures and fertilizers
Manures and fertilizer play important role in crop production. Sorghum is an exhaustive crop and it depletes soil fertility very fast. The fertilizer dose differs from type and nature of the crop. Local varieties need less than a hybrid. Similarly, the rain-fed crop needs less dose than irrigated crop. 10-15 tonnes of FYM or compost should be applied to soil before last harrowing. It improts water holding capacity and microbial population in the soil. Before application of fertilizer soil test should be carried out. Rain-fed high yielding and local varieties under irrigation should be applied at sowing. The fertilizer should be placed 3-4 cm to the side and 3-4 cm below the seed. The remaining half quantity of nitrogen should be top dressed after 30-35 days of sowing or at knee- height stage uptake of nitrogen is highest at the soft dough stage. Phosphorus uptake continues into the grain filling stage. However, potassium uptake is higher in the early stage than that of nitrogen or phosphorus.
Iron and zinc are the commonly deficient micro nutrients in sorghum. Iron deficiency is commonly found in calcareous soils. In zinc deficient soil application of 25-50 kg/ha of zinc sulphate at the time of sowing is recommended.
Thinning
Optimum plant population is important for achieving maximum yield. The first thing should be done 10-15 days after emergence and second when the crop is 20-25 days old.
Weed management
The critical period of crop weed competition is 15-35 days after sowing. If the weeds are not controlled at the proper time, there is 20-60% reduction in the yield depending on the weed intensity. Sorghum is infested with Echinochloa crusgulli, Setaria glauca, Cynodon dactylon, Elensine indica, Phragmites karka etc. Both grassy and broad leaved weeds grow with sorghum during kharif. Hoeing and manual weeding should be done to remove weeds. Pre-emergence application of atrazine @ 0.5 to 1.0 kg ai/ha controls the weeds effectively. The weedicide should be mixed with 900-1000 litres of water and sprayed on the soil at the time of spraying. Propazine (1.0-1.5 kg) can also be used as pre-emergence application. However, for post-emergence application, Trifluralin (0.8-1.2 kg) and Halosulfaron (30-40 g) are suitable. PPI of fenac, or 2,3,6, TBA or PRE herbicides simazine and propazine can give effective control of striga.
Irrigation
Sorghum is a drought resistant crop but cannot withstand water logging at any stage. Knee-height, flowering and grain filling are the most critical growth stages for irrigation if there is no enough moisture in the soil. No stage plant should be allowed to wilt. Kharif crop does not require irrigation but if there is long dry spell, one protective irrigation should be given. During rabi and summer, irrigation should be given as and when required. Suitable drainage must be provided for removal of excess of water from the field. In general, scheduling irrigation at 50% DASM or at IW / CPE ratio of 0.6 is optimum for sorghum.
Cropping systems
Sorghum is generally grown in kharif. Monoculture is a common practice due to moisture stress. Intercropping with sorghum with pulses or oil seeds is adopted. Paired planting in sorghum (30/60 cm) is most remunerative system. Maximum returns of soybean, greengram, groundnut, in paired rows of 30/90 cm with two rows of inter crop in 90 cm space. Sorghum- safflower in 6:3 or 4:2 is better in rabi. CSH-6 is the best variety of sorghum for intercropping. Some of the intercropping systems with sorghum are given below.
Sorghum-wheat-mung
Sorghum-pea
Sorghum-gram
Sorghum-potato-wheat
Sorghum-cotton
Sorghum-tobacco
Sorghum-sorghum(rabi)
Sorghum-ragi-groundnut
Harvesting and threshing
Sorghum matures in 100-115 days. Harvesting should be done when the grains have become hard and contains 15-20% moisture. Do not wait for stalks and leaves to dry as stalks and leaves remain green and succulent in most of the cultivars though grains already mature. Harvesting is done by cutting the entire plant or removing the cob first and cutting down the plant later on. Harvested ear heads are dried in the sun for a day or two until grain moisture content drops to around 12%. Threshing is done with the help of threshers or by beating the year heads with sticks or trampling bullocks.
Yield
Sorghum yields 25-30 q of grain and 80-100 q of dry stover per ha from rain-fed crop. Under irrigation grain yield is 50 q and stover yield is 100-125 q/ha.
Read about Soybean cultivation
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