Solar Powered Drip Irrigation Transforms Agriculture in Remote Village of Sundarbans in West Bengal

The Gosaba Island of Indian Sunderbans is surrounded by tidal rivers connected with Bay of Bengal, bringing water of high salinity (more than 30 dS/m), which is not suitable for irrigation in agriculture. Good quality ground water is also unavailable for irrigation due to various technical reasons. Due to these farmers in this village are unable to grow rabi crops. Farm ponds which harvest the rain water during monsoon are the only source of water for irrigation in the post monsoon period. To increase the cropped area, solar powered drip irrigation technology has been introduced in the Island under the CSI4CZ project. Analysis of monthly weather data available at Canning Town shows that the average bright sunshine hours (BSH) during the rabi season is 7 – 9 hrs a day, which is sufficient to harness the solar energy for use in agriculture. Under this technology solar panels were installed near the pond and a nano pump (0.1 hp) was used for lifting water from the farm pond to a tank (1000 litre capacity) placed at 2.5 m height on a platform. During day time, water is lifted to the tank and the stored water is applied to high value vegetable crops through drip irrigation system by gravity method. The drip discharge rate was 2.4 litres per hour. The field was divided into different plots, each plot was controlled by a valve, which facilitated crop diversification.

The solar drip system was installed in the farm of Mr. Nitai Hari Mandal in 2017. He cultivated crops like Cucumber, Bitter Gourd and Okra during kharif season by providing supplemental irrigation during deficit rainfall period. The system effectiveness was enhanced through different mulching materials such as paddy straw, black plastic, white plastic for controlling the weeds (Table 1) and conserving the soil moisture. The yield of vegetables was very promising under black plastic mulching and the crop was free from weed infestation. From October 2017, he has taken Chilli, Knol-khol and Okra. Knol-khol and Okra were harvested in January 2018. Chilli crop continued up to May 2018 which provided regular income to the farmer by selling green as well as dry chillies. After the harvest of Knol-khol and Okra he had taken bitter gourd. Thus, he is able to grow vegetables round the year by this technology. There was 20-30% more yield; saving of 40-60% irrigation water; 40% saving of labour and increase in the cropping intensity up to 300% as compared to traditional practices.

The economics of the cultivation under solar drip system (Table 2) for an area of 725 m2 indicated that the system is quite profitable in terms of gross return (Rs. 25679), net return (Rs. 13876) and output-input ratio (2.2). The profitability of the system can be further increased by increasing the area under operation as well as availing the subsidy from the government schemes.

This initiative was supported by Australian Centre for International Agricultural Research (ACIAR) has funded a project entitled “Cropping system intensification in the salt-affected coastal zones of Bangladesh and West Bengal, India (CSI4CZ)”.

Table 1. Effect of mulching with drip irrigation on weed biomass in vegetables

*Sample plot size was 153 m² under each crop

Table 2. Costs and return of crops grown under solar drip system

*Area under the system is 725 m2

(Source: ICAR-Central Soil Salinity Research Institute, Regional Research Station, Canning Town, West Bengal – 743 329)