Paddy and the price of water
Context- The southwest monsoon season (June-September) has registered 37.2% deficient rain so far. With most global weather agencies predicting El Niño — which typically suppresses rainfall in India — to fully set in by this month-end, the outlook for the rest of the season doesn’t look great.
A weak monsoon can particularly impact paddy (rice with husk). A highly water-intensive crop, its cultivation entails preparing nurseries, where the seeds are first raised into young plants that are uprooted and re-planted around 30 days later in the main field. During the nursery stage, water equivalent to one round of irrigation is given.
In all, the conventional transplanting route requires some 28 irrigations. It can go up if high temperatures force more frequent watering, and go down if there is enough rain. Each irrigation consumes roughly 5 hectare-cm or 500,000 litres of water (one hectare-cm is one cm of standing water in one hectare area, equal to 100,000 litres).
Direct seeding versus transplanting
- That’s where direct seeding of rice (DSR) comes in. Paddy here is sown directly in the field without any nursery preparation, puddling or flooding. In transplanting, the flooded fields basically deny oxygen to the weed seeds in the soil, preventing their germination. Water, thus, acts as a natural herbicide. In DSR, water is replaced with chemical herbicides.
- Sowing is done by a DSR machine after 4-5 days, when the field had sufficient workable soil moisture. Pendimethalin herbicide was then sprayed (at 1.5 litres/acre) within 24 hours of sowing. The weeds — whose small seeds in the soil germinate fast once irrigation is given — are killed on coming into contact with this “pre-emergent” herbicide.
Where DSR scores?
- “DSR is effective against weeds and saves water compared to transplanting,” . The second irrigation is required only 18-20 days after sowing. Also, a second “post-emergent” herbicide, bispyribac sodium, is applied (at 100-125 gm/acre) 20-25 days after sowing, when the crop’s main stem has produced 2-3 leaves.
- After the second irrigation, you give water every week like in transplanted paddy. The water saving in DSR comes from no puddling and flooding of fields during the initial 2-3 weeks.
- The total number of irrigations for a 155-160 days crop works out to 21-22, as against 28-plus in transplanting.
- AK Singh, director of the New Delhi-based IARI, estimated the water consumption per irrigation under DSR at only 1.5 hectare-cm (150,000 litres), way below the 5 hectare-cm for transplanting and 15 hectare-cm in puddling.
Water plus labour savings
- It takes 4-5 labourers working a whole day to transplant an acre of paddy, for which they charge Rs 4,000. A DSR machine can cover the same area in 1.25-1.5 hours, burning up to 3 litres of diesel costing Rs 90/litre.
- The cost of herbicides, spraying included, is another Rs 1,600-1,700 per acre.
Why DSR hasn’t picked up
- A key reason is subsidised or even free electricity for irrigation, providing farmers little incentive to deploy water-saving technology. A second reason — highlighted by Pritam Singh, a progressive 120-acre farmer from Urlana Khurd village of Panipat’s Madlauda tehsil — is the lack of good machines.
- The recommended spacing for paddy is 20 cm row-to-row and 15 cm plant-to-plant, allowing for a plant population of 33 per square meter. “The DSR seed drill machines mostly sow row-to-row and don’t get the plant-to-plant distance right,” he pointed out.
Way Forward- The Haryana and Punjab governments are offering farmers Rs 4,000 and Rs 1,500 per acre respectively to grow paddy using DSR, instead of transplanting. But it’s the price of water and labour, not sops, that is ultimately going to push farmers to adopt the technology.
Syllabus- GS-3; Agriculture
Source- Indian Express