Ensuring water sustainability in Punjab's agriculture requires a comprehensive strategy, including crop-specific irrigation methods, embracing advanced agricultural technologies, and effective water management practices. Agricultural stakeholders, research bodies, and policymakers must collaborate closely to safeguard the future of Punjab's farming sector in the face of rising water scarcity issues.
Overview of Water Situation in Punjab:
Despite covering only 1.53% of the nation's land, Punjab has significantly contributed to the central pool due to consistent water availability, enabling extensive rice cultivation. However, over-reliance on rice, especially during high evaporation months, has led to a notable decline in water levels. The prevalent rice-wheat cropping pattern has forced farmers to dig deeper into older aquifers, evident from the surge in tube wells from 70,000 in 1960-61 to approximately 14.82 lakh in 2019-20. Presently, Punjab faces a severe water imbalance, with a deficit of 13.06 BCM against a demand of 66.12 BCM.
Status of Groundwater Depletion in Punjab:
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Approximately 79% of the state's area is over-exploited, with overall groundwater extraction levels at 164.4%.
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A recent report by the Central Ground Water Board (2023) found that out of 153 assessment units, 114 blocks and 3 urban areas are over-exploited, with 3 blocks critical and 13 semi-critical, leaving only 20 blocks safe.
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Only blocks near major dams in sub-mountainous regions are genuinely secure, while groundwater in 11 blocks of southwestern districts is of poor quality.
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With agriculture accounting for 95% of water demand, urgent action is needed to effectively manage water resources and ensure sustainability.
Experts Recommendation from Punjab Agricultural University (PAU):
Considering the decline of groundwater resources, increasing cost of production and degrading natural resources, Punjab Agricultural University has recommended below mentioned agro-technologies in major Kharif crops for efficient use of irrigation water:
1. Paddy Cultivation:
More than 80% of the water utilized during the kharif season in Punjab is allocated to paddy cultivation, owing to its high water demand and the expansion of cultivated areas in the region. Paddy cultivation spans a period of high evaporation demand, necessitating the adoption of strategies to optimize water usage.
The university advocates the adoption of short and medium-duration paddy cultivars, which not only require less water but also offer higher yield potential. These cultivars facilitate the early vacation of fields, enabling better management of rice residue and timely sowing of subsequent wheat crops. The recommended paddy cultivars include PR 126 (seed to seed-123 days), PR 131 (140 days), PR 130 (138 days), PR 129 (138 days), PR 128 (141 days), PR 127 (137 days), PR 122 (147 days), PR 121 (140 days), HKR 47 (134 days), and PR 114 (145 days). It's advised to avoid cultivating long-duration varieties like Pusa 44/Peeli Pusa/Dogar Pusa, as they necessitate 15-20% more water.
To optimize water conservation and facilitate timely field clearance for wheat and other crops, PAU has recommended that paddy nursery should be sown after May 20 and the transplantation of paddy seedlings should occur between June 20 and July 10. For July transplanting, farmers should prioritize short-duration cultivars like PR 126. This will reduce groundwater extraction by avoiding periods of high evaporative demand and utilising the rainwater more effectively.
In puddled transplanted rice, maintaining continuous standing water for the initial 15 days post-transplanting is recommended to enhance crop establishment, suppress weed emergence, and improve the effectiveness of pre-emergence herbicides. Subsequently, adopting an alternate wetting and drying system is advised, irrigating the crop every two days after ponded water has infiltrated the soil while ensuring that the field does not develop cracks. This practice alone can save about 15-20% of irrigation water without any negative effect on yield. Irrigation should cease approximately two weeks before maturity.
For directly seeded rice in tar-wattar fields, the first irrigation should be applied around 21 days after sowing, followed by subsequent irrigations at 5-7 day intervals depending on soil type. In the case of seeding in dry fields, the first irrigation should be immediate after sowing, with subsequent irrigations at 4-5 day intervals, again dependent on soil type and rainfall. Irrigation should cease 10 days before harvesting. Direct seeding of rice not only conserves 10 to 20% of irrigation water but can also be conducted on raised beds in tar-wattar fields for additional water savings. In heavy textured soils, transplanting rice on beds can save approximately 25% of irrigation water.
Basmati rice cultivation demands less water compared to non-basmati varieties, primarily because it is transplanted later in the season. Additionally, the peak growth phase of basmati coincides with the monsoon rainfall period, further reducing water requirements. Moreover, the relative humidity is high during the growth phase of basmati rice due to the prevalent rains, consequently lowering the atmospheric evaporative demand.
2. Cotton Farming:
Cotton is primarily grown in the south-western zone of the state which is characterized by an arid climate, less rainfall, brackish underground water and poor soil fertility. Canal water is the major source of irrigation for this crop. Cotton crop is planted from April to mid-May and run through the high evaporative demand period of the season. Therefore, the maintenance of adequate moisture in the soil profile is an important prerequisite to reap a rich harvest. Cotton requires 4-6 irrigations depending upon the rainfall events. The first irrigation should be given 4 to 6 weeks after sowing and the subsequent ones at intervals of two or three weeks.
Cotton crops can be raised on ridges and a considerable amount of water can be saved by giving irrigation in furrows. If underground water quality is not good, apply pre-sowing irrigation with canal water and subsequent irrigations can be given in alternate furrows with poor-quality tube-well water. The crop should never be allowed to suffer from water stress during flowering and fruiting stages. Water stress during these stages causes shedding of flowers and bolls resulting in lower cotton yield. On the other hand, cotton during its early growth is very sensitive to water stagnation. Excess water should be drained out to protect the crop from parawilt.
It generally occurs after droughts when the crop is heavily irrigated or there is heavy rain. Plants show sudden drooping of leaves which ultimately get wilted but the root system remains intact. To hasten the boll opening, the last irrigation should be applied by the end of September. Surface drip irrigation in cotton saves irrigation water and nitrogen while achieving similar or higher seed cotton yield over the conventional method. The lateral pipes should be laid at 67.5 cm apart having inline drippers at 75 cm and dripper discharge of 2.2 litre per hour. American Bt cotton hybrids should be drip irrigated at 7-day intervals with varying times of irrigation depending on the month. The system should run about 50 minutes during May and June and subsequently 45, 40 and 35 minutes during July, August and September, respectively. Start fertigation of 100 kg urea (45 kg N) per acre at 35 days after sowing and complete in 110-120 days in 10 equal splits at 7-day intervals.
In the cotton-wheat cropping system, the sub-surface drip irrigation (SSDI) system has many advantages over the conventional method as water and nutrients are directly supplied to the active root zone of the crop. For installation of drip inlines, field should be laser levelled and well prepared with a cultivator and planker. Choose drip inline with embedded emitters at a spacing of 20 cm and discharge of 2.2 litres per hour (lph). Drip inline of approximately 6000 m is required for one acre. Use tractor tractor-operated subsurface drip layering machine to install the drip inlines at 20 cm depth while keeping the lateral to-lateral spacing of 67.5 cm.
The tractor-operated subsurface drip layering machine is available with the Department of Farm Machinery and Power Engineering, PAU, Ludhiana. The farmers can avail subsidy from the state government for the initial installation of the system. Sow one row of cotton at 67.5 cm spacing directly above each drip inline during Kharif season. During Rabi, grow three rows of wheat at 22.5 cm spacing on each drip inline. Wheat can also be sown using a zero-till drill after planking of the field by a tractor to level it by breaking the ridges developed during the previous season on cotton crop rows. In this arrangement, one lateral inline will serve one row of cotton and three rows of wheat in the respective season.
The normal inter-culture operations in cotton can be performed like conventional planted cotton using available tractor-operated machinery. In cotton, apply irrigation at 5-day intervals starting from 30-35 days after sowing (DAS). Fertigate 100 kg urea (45 kg N) per acre in 10 equal splits at 10-day intervals starting from 30-35 DAS. If emitter discharge is 2.2 litre per hour, the system should run about 40 minutes during May and June and subsequently 35, 30 and 25 minutes during July, August and September, respectively.
3. Maize Production:
Maize is cultivated mainly in Jalandhar, Kapurthala, Hoshiarpur and Kandi regions of Ropar district. From end-May to mid-June, maize should be sown in trenches prepared by tractor-drawn ridger to facilitate easy and economical irrigation during the dry and hot period. Generally, 4-6 irrigations are required depending on the rainfall. Adequate water supply is essential throughout the crop season, particularly during the pre-tasselling, silking and grain-filling stages. Maize can tolerate heavy rains provided it is not subjected to water logging conditions for prolonged periods. Flooding particularly at a young stage causes great damage to the crop. Spreading 30 quintal per acre of paddy straw mulch at the time of sowing conserves soil moisture besides suppressing annual weeds.
Maize can also be sown on beds/ridges to avoid the adverse effect of excess rainfall at seedling emergence particularly for sowing in the second fortnight of August. Sow the seed 3-5 cm deep on the top centre of the bed prepared with a wheat bed planter. Keep row-to-row spacing of 67.5 cm and plant-to-plant spacing of 18 cm. Sowing can also be done on the side preferably 6-7 cm above the base of ridges spaced 60 cm apart with plant-to-plant spacing of 20 cm. In flat sown crop, drain away excess water by making a drain of adequate capacity at the lower end of the field to avoid flooding. If damage due to excess water occurs, spray 6 kg urea per acre in two sprays at weekly intervals (3% solution) in case of moderate damage or broadcast additional nitrogen @ 25-50 kg urea per acre in case of moderate to severe damage only after receding of flooded water.
Sub-surface drip irrigation and fertigation customized to the maize-wheat-summer moong cropping system have been recommended to enhance the system's productivity, profitability, and sustainable water use. Place drip inline having dripper having 20 cm spacing at 20 cm depth with lateral to lateral spacing of 67.5 cm spacing by using tractor operated subsurface drip layering machine. Sow one row of maize, two rows of wheat and two rows of summer moong on each drip inline during the respective season.
In this arrangement, one lateral inline will serve one row of maize, two paired rows of wheat and two paired rows of summer mungbean in respective seasons. In maize, apply sub-surface drip irrigation at 3-day intervals with fertigation of 80 % recommended dose of NPK. Apply 1/5 dose of NPK at sowing and fertigate remaining P and K in 5 splits and N in 7 splits at 9-day intervals starting from 15 DAS. Use urea, mono ammonium phosphate and muriate of potash as source of N, P and K, respectively. If dripper discharge is 2.2 litre per hour, run the system for about 35 minutes during July-August and subsequently 50 and 30 minutes during September and October, respectively.
4. Fodders (Sorghum, Maize, Bajra) Cultivation:
Fodder crops such as sorghum and maize require 5 irrigations during the summer season while irrigations during kharif should be applied depending upon the rains. For multi-cut sorghum, give irrigation after every cut to promote regrowth. Under drought conditions, apply irrigation one week before harvesting the crop. Excess water should be drained out of the field to avoid crop damage. Two or three irrigations are usually sufficient for fodder bajra. However, in the hot season, more irrigation may be required.
Ensure proper drainage to avoid the water logging of fields. If possible, apply light but frequent irrigation. In case of napier bajra hybrid fodder, the vegetative growth up to first cutting is very slow therefore, apply 3-4 t/acre of straw mulch at the time of planting and irrigate the crop at 8-10 days interval till the rains start. In the mid-season, however, irrigate after every 10 to 14 days. Drain away excess water from the fields during the rainy season.
5. Pulses (Moong, Mash, Arhar, Soybean) Cultivation:
Moong and mash crops do not require irrigation during monsoon, however, if rains fail for a longer period apply irrigation accordingly. Arhar and soybean require 3-4 irrigations depending upon the rainfall. After mid-September do not apply irrigation to arhar as it delays the maturity whereas irrigation at a pod-filling stage in soybean is very useful. Arhar and soybean crops can be successfully grown on raised beds (67.5 cm apart with 37.5 cm bed top and 30 cm furrow) in medium to heavy textured soils to save irrigation water and to save crops from the adverse effects of heavy rainfall.
In addition to the above crop-specific water management techniques, the efficient utilization of available water resources could be achieved by adopting efficient water conveyance system like underground pipes systems/brick linings of water courses; by making smaller plots according to soil type for example, 8 plots (kiaras) per acre in heavy textured soils and 16 plots per acre in light textured soils; micro-irrigation and straw mulching. Precise laser leveling of land is instrumental in enhancing irrigation efficiency, resulting in water savings not only in the immediate crop but also in the subsequent crops.
(Information Provided by V K Sindhu, A S Brar and Sukhpreet Singh from Centre for Water Technology and Management, Department of Agronomy, PAU)
