Efficient MI methods and technologies developed for irrigating horticultural and vegetable crops are reported to result in 30-50% water-saving and 20-40% increase in crop yields. The DI system is more economical for orchard crops. The performance of drip and conventional (i.e. check basin) irrigation methods in banana was evaluated in clay soils at Rahuri, Maharashtra. Normal planting pattern had an edge over paired planting pattern. Nevertheless, the fruit yield and WP of banana were higher under drip than that obtained under check basin method of irrigation (Table 12.7).
Among the irrigation methods, the DI system has recorded the maximum WP compared to surface irrigation in Bhavani Basin, Tamil Nadu. The WP is expressed both in terms of product or profit per unit of evapotranspiration (ET), or irrigation water (IW) or total water used (IW + P). The maximum WP was observed for rose flower cultivation followed by grapes and banana. In general, fruit crops achieved higher WP compared to the grain crops (Table 12.8).
Verma et al. (2004) showed 23-75% increase in fruit yield of fruits and vegetables with the highest increase in papaya and the lowest increase in grapes. The DI system resulted in 36-68% water-saving with the highest in papaya and the lowest in watermelon (Table 12.9).
In arid region of Jodhpur, it is revealed that drip saves 30-50% water and provides 2-3 times higher yield compared to that obtained with the CMI. Experiments conducted at CAZRI, Jodhpur with the DI system and furrow irrigation system showed a significant amount of water-saving (50%) for potato crop without losing much yield. Adoption of the DI system in chillies resulted in 71% increase in yields over the furrow irrigation.
The effect of drip, sprinkler and furrow irrigation on long gourd, ridge gourd, round gourd and watermelon was documented by CAZRI, Jodhpur. The amount of water applied in drip, sprinkler and furrow irrigation was 69, 84 and 84 cm, respectively. The benefits of the DI system were not the same for all the crops.
The increase in yield from drip irrigation over sprinkler and furrow irrigation was 44-47% in long gourd, 21-37% in round gourd, 9-22% in watermelon and almost negligible in ridge gourd (Table 12.10). Further, water use efficiencies were 8.1,6. 5 and 11.0 kg ha -1 mm -1 in long gourd, round gourd and watermelon, respectively.
The SI system also showed superiority over the CMI, i.e. furrow in terms of yield. The demonstration of tomato cultivation by the DI system at a farmer’s field revealed that in FIM only 0.24 ha of land was irrigated as compared to 0.4 ha of land under the DI system with the same amount of water. Thus, there was an increase of 66.6% in the irrigated area.
In hot arid condition of Bikaner, Birbal et al. (2013a) reported that the DI system with plastic mulch resulted in the maximum okra yield. The DI system increased 13.5 and 12.9% fruit yield over furrow irrigation method in 2009 and 2010, respectively. Plastic mulch recorded the highest fruit yield in both the years, which was 10.2, 17.7 and 32.7% higher compared to hessian cloth, indigenous material and no mulch conditions, respectively.
In another experiment conducted on pea, Birbal et al. (2013b) reported that the DI system improved the yield up to 18.3% compared to that obtained in furrow irrigation method in pea. Thus, the efficiency of the DI system can further be enhanced by the inclusion of plastic mulching.
Gebremedhin (2015) observed that the onion irrigated at 100% ETc with DI system showed 32.8% of increase in yield over furrow method of irrigation. The amount of water saved at 100, 80 and 60% ETc under DI system was 29.4, 43.5 and 57.6%, respectively over furrow method. This also enabled irrigating 0.42-1.36 ha additional area under onion crop.
Thus, it resulted in better economic returns as compared to that obtained in furrow irrigation method. Therefore, it is emphasized that in the semi-arid regions having limited availability of water to be used for irrigation, the DI system should be adopted instead of the CMI.
The MI systems have large potential for water conservation and improved productivity. Recent studies by the International Water Management Institute (IWMI), Sri Lanka showed that the Indian States in the Indo-Gangetic basin have large areas and crops amenable to the DI system with 1.884 m ha in Uttar Pradesh, 0.192 m ha in Bihar, 0.6 m ha in Punjab and 0.374 m ha in Haryana.
In India, adoption of the DI system for suitable crops in the potential areas may lead to reduction in crop water requirements to the level of44.46 BCM (Table 12.11). However, the economic viability of the MI depends upon a wide range of factors including market and rural infrastructures. Overall, the estimates presented above suggest that the WUE is substantially higher under SI and DI systems in comparison to FIM, mainly due to reduction in conveyance and distribution losses.
It also clearly suggests that the present level of WUE under flood irrigation method is very low, which can be increased substantially by focusing more on demand management strategies such as adoption of the SI and DI systems. This would also help increasing the irrigated area without exploiting the limited irrigation potential.
Improving Quality of Produce and Lowering Energy Requirements:
The DI system has the potential to improve the quality of the crop produce because it is a form of precision irrigation, and applies water directly to the root zone. Each plant is able to receive the right amount of water at regular intervals, and less water is lost due to conveyance.
When farmers use traditional irrigation methods, such as FIM, they often tend to over-irrigate or under-irrigate their crops depending on the amount of water they are able to pump and not necessarily on the amount that their crop requires. Shashidhara et al. (2007) conducted the study on drip irrigation in arecanut and banana in Shimoga and Davanagere districts of Karnataka.
Of the total farmers interviewed, about 95% reported water-savings, 92% reported savings in labour cost involved in irrigation, and 91% suggested uniform water application. About 70% farmers obtained improved quality of the produce. Quality parameters of banana crop grown under drip system had shown more number of hands per bunch (12), fingers per bunch (103), length of fruit (12.01 cm) and fruit thickness (6.42 cm).
Bhamoriya and Mathew (2014) evaluated impact of drip irrigation on the improvement of the quality of produce by interviewing the farmers in three Indian States. About 10, 21.3 and 14.3% of the respondents in Andhra Pradesh, Gujarat and Tamil Nadu, respectively expressed a very high impact of the technology interventions on the quality of the produce. Almost 40% respondents in all the States observed a high impact.
However, around 42% of the respondents observed moderate improvement in the produce quality and similar proportions were observed in the States of Tamil Nadu (35.7%), Maharashtra (54%), Gujarat (38.9%) and Andhra Pradesh (40.6%) as well. Regarding fetching the better price due to better quality of produce, a very positive impact was perceived by 58.2% in Andhra Pradesh, 57.4% in Gujarat, 45.2% in Maharashtra and 21.8% in Tamil Nadu.
In addition to quality and yield, farmers may choose to use the DI system because it reduces labour. It allows for early harvesting of the crop, which reduces the labour costs of farmers. Weeds, insects and plant diseases have also proven to occur less frequently with the adoption of this technology, cutting down the efforts that farmers have to make to protect their crop.
The lower energy expended, when MI is used in cultivation, has an effect on the overall cost of production, making this one of the main reasons why farmers switch to the technology. Interviews with mulberry farmers in Kolar, Karnataka recorded that the labour requirement reduced drastically when shifted to DI system from FIM.
Over the last ten years, researchers studied the impact of water-saving technologies on water use pattern and productivity gain, either from observations recorded at field or from research experiments. The findings indicate that besides reducing water consumption, the adoption of MI also reduces substantial amount of energy use for irrigation purpose as the less electricity is needed and working hours of irrigation pump sets are also reduced.
To overcome the problems of high investments, frequent electric cuts and also to ensure availability of electricity on time, the non-renewable energy sources such as solar or wind energy for lifting water and irrigating the field with MI systems offers a great scope in arid as well as semi-arid regions. The Government of Rajasthan took a remarkable step by providing subsidy in promoting use of these solar pumps in irrigation, and thereby to increase the WP.
However, a necessary condition for getting subsidy is that the beneficiary should have a water harvesting structure, DI system and should grow horticulture crops. The intention was to bring the farmers out of poverty by growing cash crops, saving energy and improving water productivity.
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