Direct Seeded Rice (DSR)
By MYNENI VENKATA SAI VAMSI
Rice is one of the most important food crops and more than 50% of the world population’s staple food. India is the world’s second-largest producer of rice and the largest exporter of rice in the world. India has the largest area under rice cultivation. A significant percentage of farmers use Puddled Transplanted Rice (PTR). The main disadvantages of puddling are excessive water use and difficulty of regenerating soil structure. Soil disturbance by conventional tillage makes the soil serve as a source rather than a sink of atmospheric greenhouse gases. It is considered that rice cultivated through the PTR system is one of the major sources of methane (CH4) emissions and thus is not sustainable and environmentally friendly. It was proved that it breaks the capillary pores, and destroys soil components. It eventually leads to the formation of a hard ground surface, which in turn creates problems for the establishment and growth of succeeding crops.
Labour and water scarcity in northwest India are driving researchers and farmers to find alternative management strategies, that reduce the irrigation amount and labour requirement while maintaining or increasing yield are urgently needed, which dictate the need for the shift to (Dry) Direct Seeding of Rice (DSR). In transplanting paddy, farmers prepare nurseries where the paddy seeds are first sown and raised into young plants. The nursery seed bed is 5–10% of the area to be transplanted. These seedlings are then uprooted and replanted 25–35 days later in the puddled field. In DSR, the pre-germinated seeds are directly drilled into the field by a tractor-powered machine. There is no nursery preparation or transplantation involved in this method. Farmers have to only level their land and give one pre-sowing irrigation. Dry direct seeding of rice is an emerging production system in Punjab and other parts of the NorthWestern Indo-Gangetic Plain. Direct Seeded Rice (DSR), also called the Broadcasting method, is the process of sowing pre-germinated seeds directly into the soil mechanically. There is also less land preparation. It is considered an alternative method to traditional methods of puddled transplanting systems. Both the surface water resources and underground water resources are shrinking day by day, which makes it risky to be highly dependent on the water. After covid, the profit margins for farmers are decreasing in puddled transplanted systems mainly because of high labour costs and water requirements. So, switching over to ‘direct seeded rice’ cultivation is more relevant. There are types of direct-seeded rice based on the soil in which one sows the pre-germinated seeds. Wet-seeding involves sowing pre-germinated seed onto puddled wet soil, and then gradually flooding the land. In dry-seeding, rice is broadcast or drilled into dry soil and the seed is then covered.
Outreach of DSR is increasing, Punjab state government promoting DSR, because Direct seeding offers certain advantages like saving irrigation water, labour, energy, time, reduces emissions of greenhouse gases, along with better growth for succeeding crops, etc. Both methods of DSR (Dry and Wet) are more water-efficient and have an advantage over PTR. DSR is mostly about preparing the field for optimum soil moisture conditions and seeding.
Water use efficiency
The results of a study in the Philippines it was observed that Wet seeded rice (WSR) systems used less water than transplanted rice for both land preparation and crop irrigation and the total water use reduced from 2,195 to 1700 mm.The yield in WSR varied from 6.9 to 6.3 t/ha and water productivity increased from 0.3 to 0.4 (kg rice /m3 water) by adopting WSR.1
When compared direct seeding and transplanting methods on loamy sand soils at Ludhiana and found that water productivity varied from 0.36 to 0.46 i.e. 25% by adopting DSR with about 18% less irrigation water consumption and with comparable yield as compared to transplanted rice.2 It was observed that differences in yield between DSR and transplanted rice became larger with reduced water input.
Emission of greenhouse gas (GHG)
Rice is an important target for mitigating GHG emissions. GHG emissions, especially CO2 and CH4 from rice fields, are large and very sensitive to management practices. It is considered that rice cultivated through puddled transplanting system is one of the major sources of methane (CH4) emissions accounting for 10–20% of total global annual CH4 emissions and global warming potential was maximum under conventional-PTR.
When DSR was combined with mid-season drainage or irriregular interval irrigation (intermittent), the reduction in CH4 emissions increased from 16–22% to 82–92% compared with flooded transplanted rice.
Weed and Pest Management
Even though it is promoted as part of Conservation Agriculture (CA), it brings the burden of weeds and pests, which is hampering the farmers to adopt. In general, direct seeded rice is affected by similar pests and diseases as transplanted rice, rice blast being one of the devastating diseases. At the same time it comes with some possible solutions. For poor farmers use of natural plant-derived biocides, such as, those from neem as it is cheaper, indigenously available and eco-friendly products. Integrated weed management, systematic weed monitoring programme, hill seeding, lodging resistant cultivars, integrated management as well as bio-technological and genetic approaches may help resolve insect, pest and disease issues.
Conclusion
DSR with suitable conservation practices has the potential to produce slightly lower or comparable yields to that of TPR and appears to be a viable alternative to overcome the problem of labor and water shortage. If not managed efficiently, weeds may cause partial to complete failure of DSR crops. As it decreases the stress on the water table and environment by reducing the usage of water and GHG emissions. This is a small change to potentially influence the damages that are being done to the environment in the process of Rice production.Dry direct seeding of rice is an emerging production system in Punjab and other parts of the NorthWestern Indo-Gangetic Plain. Especially because of the depleting ground water table, Punjab state government since 2020, added to this the pandemic made the migrants stuck at their native places which increased the relevance fot DSR.
Way Forward
In the Third phase of promoting DSR in Punjab by the state government, DSR failed to give good yields. This is because of other factors, mainly, very poor rainfall, electricity, and the issue of weeds4. This might demotivate farmers from adopting DSR. To tackle this, the governments have to focus on educating farmers regarding the benefits and practices of DSR. Governments should be ready to supply basic inputs like electricity and better weedicides. Government should allocate adequate funds for the departments for these activities and beyond like displaying of success stories and for maintaining Krishi Vikas Kendras for training and to increase connectivity to farmers.
Acknowledgements
Direct Seeded Rice: Prospects, Problems/Constraints and Researchable Issues in India. (Link)
References
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Corton, T. M., Bajita, J., Grospe, F., Pamplona, R., Wassmann, R. and Lantin, R. S. Methane emission from irrigated and intensively managed rice fields in Central Luzon (Philippines). Nutrient Cycle Agroecosystem. 58:37–53.LINK
Direct-seeded rice: Why this water saving method failed in Punjab this year, Shagun, 5th July 2022.LINK
Vatta, Kamal & Singh, Jasdev & Kaur, Parminder & Bhardwaj, Sumit & Singh, Kashmir. Direct Seeding of Rice in Punjab. Policy suggestions. 2021.LINK
