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Weed Management strategies for Sustainable Rice Cultivation under dry seeding environment

Rice is an integral part of life as it is the staple food for over half of the world’s population. And to meet the global rice demand, about 114 million tons of additional milled rice needs to be produced by 2035(Source: www. fao.org/faostat). The need of the hour is to solve the world’s food problem through innovations in agriculture backed by technology, while putting our people first – farmers, consumers and the future generations. 

Currently, rice is grown in more than 158 million ha in over 110 countries. Asia being the biggest consumer, the consumption per capita varies from 186 kg per year in Myanmar to a low of 4 kg per year in USA. Asia has more than 200 million rice farms, most of which are smaller than 1 hectare. In India, we grow rice on 43.2 million ha, with an annual production of about 110 million tons of paddy. (Source: www.ricepedia.org)

Rice is cultivated under diverse growing environments in India. It is primarily grown as a tropical and subtropical crop and can be cultivated at an altitude from sea level to about 3,000 meters. Depending on geography, soil type, rainfall distribution, irrigation facility, and labor availability, the crop is established either by direct sowing (broadcast or drilled) or by transplanting. 

Rice also grows under diverse water regimes. It is an upland crop, where there is no standing water and mostly rains are the sole source of moisture, hence irrigation availability is very limited. It is also a lowland crop, in which water, derived either from rain or irrigation systems, remains standing in the fields. Shortage of water, soil health and climate change are challenges that are threatening the productivity and sustainability of rice-based systems. The emerging energy crisis and rising fuel prices exacerbate the issues.

Direct seeding, still not so prevalent in India, it is the process of growing crops under a dry seeding environment. It involves sowing rice seeds directly into the soil rather than transplanting seedlings from a nursery. The process has several advantages - saves labor, requires less water, less drudgery, early crop maturity, low production cost, better soil physical conditions for following crops and less methane emission.

There are two types of Direct Seeded Rice (DSR). One is dry DSR where rice is grown like any other upland crop, with dry seed placed in dry soil by a seed drill as found mostly in North India or broadcasting followed by ploughing, as is done in Tamil Nadu. The other type is wet DSR under which sprouted seeds are broadcast or placed with a drum seeder under puddled or wet soil conditions. 

Though growing of crop under a dry seeding environment has several advantages – most important being water conservation - it also has challenges, particularly that of efficient weed management for sustainable rice production. 

Land preparation by precision land leveling and summer season plowing is an important part of weed management. Sowing time must be kept in mind based on rainfall pattern, temperature and duration of variety/hybrid and the crop’s adaptability and maturity period under dry conditions. Understanding the period of crop weed competition is critical because in dry DSR condition, from day one, weed starts converging with crop, posing a threat. The first 4 – 6 weeks period is very critical for weed management as controlling the weed at this stage will result in better yield. The weed flora in dry direct seeded rice as against wet seeded rice is more of aerobic weeds particularly grasses. An herbicide program-based approach to cover all the stages - pre planting, pre-emergence, post-emergence, and spot application – is the right approach.

Rinskor TM active(to be launched in India), a new systemic, broad spectrum post-emergence herbicides provides an alternative solution to the farmers for managing weeds effectively under different rice growing environments for control of economically important grass, broadleaf, and sedges. These herbicides contain no petroleum distillates and have low use rate.

Farmers expect reduced input costs and better return on their investments. Water and labour saving will lower input costs. Alternate planting methods such as DSR or mechanized drilling will reduce labour requirement thus achieving cost and production efficiencies. A farmer-centric approach to arrive at solutions for direct seeding and transplanting environments will hold the key to sustainable rice cultivation. Integrated weed management will be the key to success in the dry seeding environment.

Source: krishijagran.com