Tips for Rice Cultivation

Background

Rice is a stable food for more than half of the world’s population. The global population will increase from six to ten billion by 2050 and the challenge is to produce 40% more rice by 2050 to meet food security. The abiotic, biotic stress and nutrient deficiencies are the major production constraints for rice productivity optimization.

To overcome this, careful agronomic management, integrated nutrient management and integrated pest management become inevitable.

Rice cultivation methods

There are many methods of rice cultivation followed in various countries such as broadcasting, drilling, transplanting and recently, new techniques like direct seedling of rice (DSR) and system of rice intensification (SRI) are adopted by farmers to increase their yields.

Most of the farmers still practice traditional transplanting method where in paddy seeds are sown in 1/20th of the total field area as a nursery and 25 day seedlings are then transplanted into the main field. In broadcasting method, seeds are scattered in the entire field whereas in DSR, the seeds are directly drilled into the main field without the need for nurseries and transplantation.

SRI cultivation is a method of cultivating rice with young seedlings planted at a wider spacing in a square pattern and with intermittent irrigation to keep the soil moist and frequent inter-cultivation to aerate the soil.

Sowing and Seed rate

Rice can be cultivated on a wide range of soils such as silt, loam and gravel even in acid and alkaline conditions. Rice is generally grown in the Kharif season in India and is grown in Rabi and summer where irrigation facilities are available.

The usual seed rate for broadcasting is 35-40 kg/acre, for dibbling method it is 25-30 kg/acre, for transplanting it is just 4-5 kg/ acre, for DSR method seed rate is 8-10 kg/acre and for SRI cultivation, it is only 2 kg/acre.

The general spacing between seedlings in the main field is 15 x 10 cm and in SRI cultivation, it is higher at 25 x 25 cm. The healthy and disease-free seed should be select for sowing and seeds should be treated with carbendazim @ 2-3 g/ kg of seeds to control seed-borne diseases. Seed treatment with bio-fetilizers Pseudomonas fluorescens at the rate of 10 gm/kg of seed or with Azospirillum at 600 gm/ha or phosphobacteria at 1200 gm/ha.

Water management

Based on the water requirement, there are three types of rice ecosystems which are wet system, dry system and semi-dry system.

• The wet system is also called irrigated rice and it includes SRI cultivation, transplanting puddle lowland rice and direct wet seeded puddle rice.The depth of irrigation in wet systems can be increased from 2.5 cm onwards progressively along with the crop age.
• In dry systems, fields are ploughed and harrowed in summer for achieving the required tilth and seeds are sown directly with the onset of monsoon showers, either by broadcasting, dibbling behind the plough or by drilling in lines.
• In a semi-dry system, seeds are sown in dry ploughed soil after monsoon rains. Whenever water is available after the onset of monsoon, it is treated as wet paddy.
• The most critical stages of rice for water requirement are panicle initiation, booting, heading and flowering stage. Maintenance of proper irrigation in these stages enhances crop yield in both wet and dry systems of rice cultivation. In the SRI method, regular watering keeps the soil moist but not at saturated levels that can save up to 40-50% of the water from planting to harvest.

Weed management

Weeds are more prominent in the SRI method and dry system of rice cultivation because of wider spacing and less water saturation respectively. At least 4 rotary weeding’s and two hand weeding’s are required at 10 to 15 days interval up to the panicle initiation stage in SRI cultivation. Pre-emergence herbicide and hand weeding at 30 days after transplanting are recommended in the wet system of rice.

First, hand weeding between 15 to 21 days after sowing (DAS) and second, hand weeding after 35-40 days of first weeding or application of pendimethalin 1 kg/ha after 5-8 DAS and followed by one-hand weeding at 30-35 days DAS in the dry system is profitable to the farmer.

Soil nutrient management

Application of 12.5 tonnes/ha of farmyard manure or compost or green manure at the rate of 6.25 tonnes/ha is recommended to enhance the yield in rice.

Biofertilizers like Azospirillum @ 2000 gm/ha and 2000 gm/ha of Phosphobacteria or 4000 gm/ha of Azophos inoculants with 25 kg of FYM and 25 kg of soil and broadcast the mixture uniformly in the main field before transplanting and Pseudomonas fluorescens (Pf 1) at 2.5 kg/ha mixed with 50 kg of FYM and 25 kg of soil and broadcast the mixture uniformly before transplanting.

Blanket application of 150:50:50 kg N : P2O5 : K2O/ha in the wet system and 50:25:25 kg N: P2O5 : K2O/ha in the dry system is recommended. About 25 % of recommended N and K can be applied before transplanting and all the recommended P may be applied as basal or incorporated in soil. In zinc-deficient soils, application of 25 kg of zinc sulphate with 50 kg sand just before transplanting is recommended to overcome deficiency.

Azolla in association with blue-green alga Anabaena can fix atmospheric nitrogen (N) into ammonia which can be utilized by rice plants when they are incorporated into the soil. Azolla contains 2−5% N, 0.3−6.0% Potassium (K). Azolla can be used in two ways: 1) as green manure incorporated before transplanting, and 2) as an intercrop incorporated after transplanting. In each case, about 500 kg (fresh weight) per ha is introduced into standing water in the rice field.

Farm site specific fertilizers and manure application should be followed by farmers if they know the nutrient status of their soils as provided in their soil health cards.

Integrated pest and disease management (IPM)

Major diseases in rice are blast, bacterial blight, sheath blight, false smut and brown spot and major pests are yellow stem borer, brown plant hopper, leaf folder, gundhi bug and gall midge. Integrated Pest Management is an eco-friendly approach for managing pest and disease problems.

IPM utilizes all possible available methods and techniques such as cultural, mechanical, biological and chemical methods in a compatible and scientific manner to suppress the pest population to below the economic injury level.

Cultural practices such as selection of resistant/ tolerant variety, early/ timely sowing, proper spacing between plants, balanced fertilizer application, proper water management and harvesting of crop up to ground level can help in the reduction of pest and disease.

Mechanical practices such as clipping of rice seedling before seedling, removal and destruction of disease/pest-infested plant parts, use of rope in rice crop for dislodging of larvae and collection and destruction of egg mass and larvae could decrease pest and disease spread. Biological agents such as spiders, water bug, frogs, mirid bugs, damselflies, dragonflies, grasshoppers, coccinellids, bracons, wasps, Trichogramma, Telenomus, etc should be conserved to reduce the pest population.

Chemical pesticides are to be applied on a need base and judiciously at right time at the recommended dose.

Harvest of Rice

Harvesting at the right time and in the right way maximizes grain yield and minimizes grain losses and quality deterioration. The right stage for harvesting is when 80% of panicles have 80% ripened spikelets and their upper portion is straw-colored. Grains should contain about 20% of moisture. Storage grain moisture levels should be at 12 % and if you notice a forecast of rains during harvest, you should spray 20 % NaCl which accelerates maturity by 3-4 days.

Conclusion

In conclusion, farmers should opt the method of rice cultivation based on their water availability.

SRI cultivation can save up to 40% of water but require proper sowing and maintenance skills.

Any cultivation method in rice with recommended water management, nutrient management, weed management and integrated pest and disease management helps in increasing the yields. Correct identification of pests, diseases and nutrient deficiencies in the right time with Plantix helps in the control of those problems and can reduce yield losses in rice.