Shun long-duration varieties to conserve water

Raj Kumar and BS Dhillon

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The Central Ground Water Board and the Water Resources & Environment Directorate of Punjab published a report, ’Groundwater Resources of Punjab — as on March 31, 2017’, in which it is stated: “If the present rate of extraction continues, the available groundwater resources may exhaust in 20 to 25 years.” The exploitation of underground water resources is evident from the fact that the number of blocks in Punjab in which groundwater has been overexploited increased from 53 in 1984 to 109 in 2017 and safe blocks decreased from 36 to 22.

Rice cultivation

The major user of water is by the agriculture sector. Since the 1960s, agriculture has moved from subsistence to intensive farming. The focus has been on rice and wheat in order to ensure food security. Both have witnessed the development and popularisation of improved technologies. Of these two crops, rice has higher irrigation requirements and is known as a ‘water guzzler’. From 1965-66 and 2020-21, the area under rice in Punjab increased from 2.93 to 31.49 lakh hectares (10.7 times) and production rose from 4.39 lakh tonnes to 208.83 lakh tonnes (47.6 times). Simultaneously, the number of tubewells shot up from 26,000 to 14.82 lakh. This has put immense pressure on groundwater resources.

To meet this challenge, water-saving technologies such as laser land leveller, short-duration rice varieties (SDVs) and tar-wattar direct seeded rice (DSR) have been developed. The laser leveller has become popular across the state and DSR is picking up. SDVs are popular in some districts.

Rice varieties having variable duration are under cultivation in Punjab. Among long-duration varieties (LDVs), the most popular is Pusa 44 — 18% parmal area in triennium ending (TE) 2020-21). Pusa 44 and others like Peeli Pusa and Dogar Pusa mature in 160-167 days after seeding, whereas PR122 and PR118 take 150-157 days. Among SDVs, PR121, the most popular one (23.7% area during TE 2020-21), takes 140 days to mature. PR126 takes the least number of days (123) and is the third most popular variety (12.8% area during TE 2020-21). Others (PR114, PR127, PR124, HKR47) mature in 134 to 137 days after seeding. LDVs need more irrigations than SDVs, and are more responsible for the depletion of underground water. Surveys conducted by PAU revealed that LDVs occupied 51-78.7% of parmal area during TE 2020-21 in the districts of Barnala, Moga, Bathinda, Sangrur, Mansa, Ludhiana, Sri Muktsar Sahib and Faridkot, the highest being in Barnala.

Sangrur district had the lowest groundwater table (32.4 metres) in 2018, followed by adjacent Barnala district (29.7 metres). These districts had the fastest rate of groundwater table fall from 1998 to 2018. The predominance of LDVs in these districts prompted us to undertake a comparative analysis with another set of two contiguous districts (Amritsar and Tarn Taran) that have a similar cropping system but a contrasting water table scenario.

Sangrur and Barnala districts are jointly designated as Region-I. Both have rice as the primary kharif season crop, occupying around 92% of the area. Amritsar and Tarn Taran districts represent Region-II. The average annual rate of water table fall in Region-II from 1998 to 2018 was almost half (43-57 cm) than that in Region-I (103-107 cm).

Rice-wheat is the predominant cropping system occupying about 90% of the cultivated area in both regions. The varietal patterns of wheat and basmati were similar in both regions but that of parmal was contrasting. In Region-I, LDVs were cultivated on 68% of the parmal area and SDVs on only 32% area. In Region-II, SDVs occupied 95.8% area and LDVs, 4.2%. Farmers in Region-I probably believe in the higher yield of LDVs versus SDVs and consequently higher economic returns.

The average yield per hectare (ha) of not only parmal (876 kg) but also basmati (1,065 kg) and wheat (484 kg) is higher in Region-I. Evidently, the income is also higher in Region-I. One is tempted to attribute the higher yield of parmal in Region-I to LDVs. But the average yield of wheat, basmati and SDVs of parmal is also higher in Region-I. This must be due to the favourable agro-climatic endowments in Region-I. Therefore, the adoption of SDVs may not adversely affect the returns from parmal in Region-I.

Some baby steps are proposed to reduce the use of water, with the focus on rice cultivation:

• Launch a special campaign to motivate Punjabis to adopt water-saving technologies/practices in agriculture and other sectors.
• Promote cultivation of SDVs as these have 15-25% less water requirement than LDVs. The seed of SDVs may be supplied free of cost in at least Sangrur or Barnala. It will not have large financial implications as the rice area is small (2.89 lakh ha in Sangrur and 1.14 lakh ha in Barnala during TE 2020-21) and the seed rates are also not high.
• Though the yield of SDVs is marginally lower than that of LDVs, the net income is comparable because of saving in pesticides, labour and water in SDVs.
• Cultivation of SDVs makes rice straw management easier as these varieties produce lesser quantity of straw and also help vacate the field earlier and thereby widen the window between rice harvesting and wheat sowing.
• Expand coverage of successfully demonstrated DSR technology by focusing the campaign on the time and method of direct seeding recommended by PAU and allaying the concerns of farmers on weed management
• Strictly implement the Punjab Preservation of Subsoil Water Act, 2009. This Act empowers the government to notify the date to start rice transplantation.

The future of not only the coming generations but also of the present young generation is at stake. The main focus has to be on creating awareness. This is a wakeup call.

Raj Kumar is Principal Extension Scientist (Agricultural Economics) and BS Dhillon is former VC, PAU