In India, attempts have been made in the past to grow field crops such as rice, wheat and other grain crops with SI system, and it was found that the sprinklers improved the on-farm irrigation efficiencies up to 80% under the prevailing climatic conditions.
It is experienced that wheat, paddy, maize, groundnut, sunflower, chickpea and green gram are the important field crops that can suitably be grown by using the MI systems. Recent studies have shown that MI gives the higher yield for wheat and other grain crops than that obtained under CMI. Experiments carried out for various crops at different locations of Tamil Nadu Agricultural University (TNAU), Tamil Nadu, also clearly reveals the fact that SI system can be useful to farmers in terms of water-saving and yield increase in crops like green gram, chickpea, groundnut and soybean; see details in Table 12.4.
Field experiments conducted in semi-arid regions of Rajasthan also suggest that gains in terms of water-saving and productivity increase due to SI system are substantial in different crops. An evaluation study carried out in Rajasthan using a sample data of 56 farmers shows that the SI system helps increasing the area devoted to remunerative crops like wheat and mustard in rabi seasons.
The increased irrigated area also generated additional income to the adopters of SI system, besides substantially increasing the wage employment. The study further underlines that the benefits could have been higher if the power supply had been available for a longer duration during the cropping seasons.
Another study carried out in Barmer district of Rajasthan also indicates that the adoption of SI system increases the gross irrigated area, cropping intensity and helps farmers to switch over to cash crops like cumin, isabgol and mustard, etc. The study reveals that the SI system is used mainly for irrigating rabi crops, though it was used sparingly for kharif crops like pearl millet in case of monsoon failure.
i. Maize:
Field experiments conducted on maize-based intercropping system at TNAU, Tamil Nadu showed that the DI system saved up to 43% of water, besides enhancing the water productivity. Higher net returns, i.e. Rs.56,858 ha -1 and B-C ratio, i.e. 3.24, were obtained under drip fertigation with 150% recommended dose of fertilizer and radish as intercrop.
ii. Rice:
In a three-year field experiment, the feasibility of using subsurface drip irrigation for rice crops showed that the water use in drip-irrigated paddy during 2002, 2003 and 2006 was 55, 47 and 48% of flood-irrigated paddy, respectively. Trials conducted by the TNAU, Jain Irrigation Systems Limited (JISL) and International Rice Research Institute (IRRI) showed that water use in paddy cultivation using drip irrigation may reduce water requirements by 66% as compared to FIM, which correspondingly cuts down about 50% of the power consumption.
Water use in drip irrigation was 900 mm in comparison to 2650 mm under the conventional method of growing paddy in standing water. These findings are based on the trials conducted by JISL in Maharashtra, Andhra Pradesh and Tamil Nadu. To compensate high cost of drip in paddy, rice- vegetables cropping may be adopted. Kundu et al. (1998) demonstrated that SI system can also be used successfully even for cultivating paddy crop.
iii. Wheat:
Based on a field experiment on wheat, Mohamed and Salah (2011) demonstrated that the wheat yield was increased in drip irrigation (6.2 tonnes ha-1) in comparison to sprinkler (5.0 tonnes ha-1) and flooding (3.9 tonnes ha-1). The WP was estimated as 0.99, 1.17 and 1.50 kg nr3 in flooding, sprinkler and drip irrigations, respectively. Drip irrigation performed better and WP was improved by 52 and 28% in comparison to flooding and sprinkler irrigation, respectively. Efforts to increase productivity of wheat revealed that drip irrigation can increase yield of wheat by 15-30% over the central India besides decreasing the water use by 20-28%.
Trials with the DI system yielded 5.5 tonnes ha-1 in comparison to 4.69 tonnes ha1 under flood irrigation at Nasik. Experiment at Jalgaon revealed similar kind of findings with 4.1 tonnes ha-1under drip as against 2.98 tonnes ha-1 under flood irrigation (JISL). In India, about 28.9 m ha area is under wheat cultivation, and in flood irrigation, about 127 to 130 billion cubic meter (BCM) water is used. If we could bring 25% area under drip, 50% area under sprinkler and remaining 25% area under flood, then 13.7 BCM water can be saved.
The MI technology can revolutionize wheat cultivation if adopted in the major wheat growing areas of India besides saving water applied for irrigation. Bandyopadhyay et al. (2010) reported that 20 cm irrigation supplied up to flowering stage or 14 cm irrigation supplied up to tillering stage of wheat, through SI system in 4 and 3 splits, respectively resulted in higher grain yield and WP of wheat in a vertisol than that in FIM.
iv. Groundnut:
The SI system is highly suitable for groundnut cultivation. Experiments conducted at Gujarat Agricultural University (GAU), Sardar Krushinagar during three summer seasons of 1990, 1991 and 1992 showed that WUE was higher in all schedules of sprinkler and saved about 9.6- 53.9% irrigation when compared to surface irrigation method.
The net income per unit depth of irrigation water used was found to be more under all the sprinkler irrigation schedules over flooding method of irrigation. Dhawan (2002) reported 17% improvement in groundnut yield and 40% improvement in WP due to the use of SI system as compared to CMI.
v. Sugarcane:
Several studies were carried out for sugarcane, which observed substantial water-saving and productivity gains due to DI system. The study conducted in Maharashtra in 400 ha of sugarcane, area under DI system showed that drip-irrigation required 94 cm of water ha -1 as against 215 cm in conventional FIM. The cane yield observed under DI system was 170 tonnes ha-1 as against 128 tonnes ha-1 using the CMI. This resulted in a net saving of 65% in water use and also improved cane yield by 33%. The WP increased from 6 kg m-3 (flood irrigation) to 18 kg m-3 (drip irrigation).
Water management studies in sugarcane conducted at Rahuri showed that the DI system saved more than 60% water compared to furrow method, and produced 12-15% more cane yield. In an effort to lower down operational cost of drip system, planting pattern was also changed to cut down initial investment on laterals and drippers.
Three distinct patterns of planting, viz. normal, paired row and pit method were evaluated. The yield in paired row planting in drip irrigation method was better than surface irrigation methods, indicating that the cost of drip system could be reduced by adopting paired row planting (Table 12.5).
vi. Cotton:
Narayanamoorthy (2009) compared cotton cultivation under DI system and FIM. It was revealed that the DI system reduces cost involved in irrigation by 50%, and helps reduce the cost on weeding, intercultural and preparatory works. Water-saving with DI system is about 45% of that with FIM. This further saves the electricity consumption of about 350 kWh ha-1 compared to flood irrigation.
The productivity of drip-irrigated cotton is about 114% higher than that of the flood-irrigated cotton. The main reason for substantial water-saving under DI system is that the farmers are able to supply required quantity of water at the required time exclusively at the root zone of the crop. However, the farmers are unable to meet the irrigation water requirements timely under FIM.
The farmers following FIM reported that they were not able to supply adequate quantity of water during crop growth mainly due to water shortage in the well and frequent interruptions in electricity supply. Therefore, the cotton crop had to face either moisture-stress or excess-wetting throughout the crop-growing season, which had significant impact on crop growth. In fact, by adopting DI system, the farmers were able to save about 467.5 hp hour of water per ha, which is about 45% saving over FIM.
Drip irrigation in cotton at 0.8 ETc (crop evapotranspiration) gave 27.5% higher seed cotton yield compared to yield with furrow irrigation (1801 kg ha-1) at the Central Arid Zone Research Institute (CAZRI), Regional Research Station, Pali. Decrease in seed yield of cotton was 6.3% at 0.8 ETc and 25.5% at 0.6 ETc irrigation levels compared to full irrigation (1.0 ETc).
vii. Cumin:
The results of the experiments conducted in semi-arid region of Ajmer (Rajasthan) showed that the SI and DI systems enhanced the yield of cumin by 177.7 and 85.8 kg ha-1 during 2010-11 and 79.1 and 180.3 kg ha-1 during 2011-12, respectively. The WP was also improved by 47.8 and 33.1 kg ha-1 cm-1 during 2010-11 with SI and DI systems, respectively; 13.28 and 32.85 kg grain ha-1 cm -1 with SI and DI systems, respectively during 2011-12 than that with FIM (Table 12.6). Method of sowing is also reported having significant effect on WP. The WP was improved by 16.6 and 7.7 kg ha-1 cm -1 during 2010-11 and 15.1 and 1.5 kg ha-1 cm-1 during 2011-12 with sowing of 3 rows of cumin on raised beds (75 cm) and 6 rows of cumin on wider raised beds (150 cm) as compared with flat beds.
