Rice Cultivation and Production
Introduction
Rice is widely cultivated in India and is the staple food of people from Southern and eastern parts of India. China is the leading producer of rice in the world followed by India. West Bengal is the leading rice producer state in India followed by Uttar Pradesh, Telangana, Andhra, Punjab, Orissa, Bihar, Chhattisgarh, Tamil Nadu, Assam and Haryana. Generally, rice cultivation needs a lot of water and is also labour intensive therefore, it is practiced in those places wherein the labour cost is less and rainfall is high.
Scientific Name: Oryza sativa (Asian Rice) and Oryza glaberrima (African Rice).
Family: Poaceae.
Paddy is monocot having fibrous root.
Climate
- Tropical climate.
- Rice can grow from sea level to an altitude of 3000 meters. However, Paddy cultivation can also be done in temperate and sub-tropical climate under humid conditions.
- A high temperature, humidity and sufficient rainfall with irrigation facilities are the primary requirements of paddy cultivation. It also needs bright sunshine with temperature ranging between 20 and 40⁰C.
- It can tolerate temperature up to 42⁰C.
Season for Rice Cultivation
India has three rice farming seasons- summer, autumn and winter. However, the chief rice growing season is ‘kharif’ season also called ‘winter rice’ due to harvesting time in winter. The sowing time is June-July and is harvested during November- December months. 84% of the country’s rice supply is grown in the kharif crop.
Rice cultivated during rabi season is also called as ‘summer rice’ due to harvesting in summer. It is sown in the months of November to February and harvested during March to June. 9% of total rice crop is grown in this season. Early maturing varieties are normally grown during this time.
The pre-kharif or ‘autumn rice’ is sown during May to August. Based on rainfall and weather condition, the sowing time may differ slightly from place to place. Generally, it is harvested during September- October months. 7% of the total rice crop in India grows in this season and short duration varieties which mature within 90-110 days are cultivated.
Soil
- Region with high level of humidity, sufficient rainfall with irrigational facilities, and a high temperature, rice can be grown in almost every type of soil.
- The major types of soils for rice cultivation are black soil, red soil (loamy and yellow), laterite soil, red sandy, terai, hill and medium to shallow black soil.
pH
Rice can be cultivated in both acidic as well as alkaline soil.
Agronomic Practices
Land preparation
The field is prepared by ploughing the rice fields with soil turning plough followed by harrowing. The rice field is filled with water and is puddled twice by paddy puddler or once by rotavator. If green manure crop like dhaincha or mung has been taken, it may be mixed with rotavator during puddling followed by planking. Depending on water availability and weather condition, rice is cultivated by two methods.
- Wet cultivation system: Practiced in areas where the rainfall is abundant clubbed with abundant water supply. The land is thoroughly ploughed and flooded with water upto 5cm in depth. In case of clayey or loamy soil the depth must be 10 cm. Post puddling the land is levelled so as to ensure uniform water distribution. Seedlings are sown or transplanted after levelling.
- Dry cultivation system: Practiced in areas where irrigation facilities are unavailable and water is scarce. The soil must have a good tilth hence it must be ploughed thoroughly. In addition, farm yard manure must be distributed on the field uniformly at least 4 weeks before sowing. The seeds are then sown with 30 cm spacing between the plants. The land is thoroughly ploughed and flooded with water upto 5cm in depth. In case of clayey or loamy soil the depth must be 10 cm. Post puddling the land is levelled so as to ensure uniform water distribution. Seedlings are sown or transplanted after levelling.
Seed rate: The seed rate of rice varies based on the methods of sowing/transplanting. In broadcasting method seed rate is about 80kg/ha under transplanting method it is about 20- 30 kg/ha and under SRI method seed rate is only 5-8 kg/ ha.
Seed treatment: Seed treatment is done by dissolving 10 g carbendazim (Bavistin) and 1g streptocycline in 10 litres of water sufficient for 10 kg seed. The soaked seed should be for 24 hours before sowing or transplanting. The soaked seeds are covered till it is sprouted.
Sowing Method
There are different practices of cultivation of rice, viz. transplantation method, drilling method, broadcast method, Japanese method and, SRI method.
Mostly nursery bed method is followed. The paddy seeds are sown in the nursery bed which occupy about 1/20th of the total field area. Plants become ready for transplant within 25 days of sowing in low land areas while in higher altitudes they take about 55 days to become ready for transplantation.
- Direct seeding or Broadcasting method: Seed is directly sown in unpuddled and puddle field prepared for sowing at appropriate moisture level.
- Transplanting method: In this method a nursery is prepared for transplanting of rice. For manual transplanting the nursery is prepared in 1/20th of transplanting usually on raised beds. For mechanical transplanting the nursery is raised as mat or tray nursery. The 25 days old seedlings (4-5 leaf stage) uprooted from the nursery bed are the transplanted 3-4 cm deep following 20cm x 10cm spacing with 2-3 seedlings/ hill in the line planting and 10cm x15 cm in random planting.
- Drilling method is exclusive to India. In this method, one person ploughs a hole in the land and the other person sows the seed. Ox is the most commonly used ‘person’ to plough the land.
- Broadcast method generally involves scattering of the seeds manually over a large area or in the entire field. Labour involved is very less and so is the precision. This method produces very less yield as compared to others.
- Japanese method has been adopted for the high yielding variety of rice and those that need a high amount of fertilizers. Seeds are sown in nursery beds and then transplanted to the main field. It has shown tremendous success for the high yielding varieties.
Manures and Fertilizer
The fertilizers and organic manures may be applied based on available soil nutrients after the soil tests.
In general, about 80-100 kg nitrogen /ha is applied in 3 split doses; half (40- 50 kg) as basal dose, one forth (20-25 kg) at tillering stage and remaining a week before panicle initiation where top dressing is not possible. Along with basal dose (50% of nitrogen) 40-45 kg P2O5and 30-40 kg K2O are also applied depending on soil test.
Bio fertilizers such as blue green algae or Azolla provide 20-25 kg N/ha, which may be added as partial supplement to inorganic fertilizer. The application of micro-nutrients may also be applied based on soil test.
Water management
Uniform levelling of field and proper drainage is most essential for an effective water management in irrigated field. Efficient water management facilitates good tillering and better nitrogen uptake and helps in reducing weed population.
Water scarcity is a big problem around the world hence some measures can be adopted like:
- Filling the cracks in soil to avoid loss of water,
- Separate field channels are constructed to allow water to be delivered to individual seed beds.
- Levelling the field as a field uneven in level consumes nearly 10% extra water than what is necessary for growth.
- Proper bunding as Bunds form a boundary and hence limit water loss. They must be compact and high enough to avoid overflowing of water in case of rains.
Plant Protection
Weed management:
Usually, 2-3 hoeing or manual picking of weeds are required to control the weeds. Some herbicides such as Anilophos, Butachlor, Anilophos+ Ethoxysulfuron, Pyrosolfuron-ethyl, Almix +Butachlor, Fentrazamide, Cinmethyline+2,4D are used.
Diseases Control:
- Khaira: 5kg zinc with 2.5 kg lime (in 1000 liters of water) / ha 10 days after transplanting.
- Blast: Seed treatment with thiram @ 2.5g/kg of seed or tricyclazole 75 wp @ 1.5 g/ kg of seed.
- Brown spot: Carbendazim 50wp @ 2.0 g/kg seed or Mancozeb 75wp @ 2.5g/kg.
- Bacterial leaf blight: Seed treatment with streptocycline (1g) + carbendazim 50 W.P. (20g) for 8–10 kg of seed in 10 litres of water for 12 – 15 hours.
Insect Control
- Gundhi bug: Spray carbaryl 50 wp @1,500 g/ha during afternoon hours.
- Stem Borer: Spray Cartap 50 wp @800 g/ha chlorpyriphos 20EC 2,000 ml/ha.
- Brown plant hopper: Spray Imidacloprid 200Sl@125 ml/ha.
Harvesting
Irrigation of the field is completely stopped about a week before harvesting. In case of early and medium maturing varieties, harvesting should be carried out 25- 30 days after flowering. The late maturing varieties are harvested 40 days after flowering.
The crop should be harvested when the grains turn yellow and moisture content is below 25 %.
Crop Rotation
Legumes are the most commonly used crops used for crop rotation with rice especially in lower water supply areas. Rice in such places is cultivated only once a year and the rest of the year the land is fallow. Hence planting legumes in such period would optimize land use and also help increase fertility of soil.