Water and energy conservation through Tensiometer device

A low-cost, farmer-friendly device to measure soil moisture by saving water and energy in paddy irrigation in Punjab

BACKGROUND

Indian Punjab is a leading agricultural state, with about 4.2 million hectares (mha) of net area sown and almost one million operational land holdings. Introduction of high yielding varieties of rice and wheat coupled with assured irrigation and use of modern inputs (fertilizers and agrochemicals), during the Green revolution era of the late 1960s and early 1970s, has led to substantial changes in the production and productivity of the state. The government has also supported and assured farmers for procuring their produce at remunerative prices. However, intensive agriculture has led to over-exploitation of groundwater resources in the state, stimulated in part by a decrease in average rainfall, increasing rainfall variability and growing over-dependence on groundwater resources. Almost the entire cropped area in Punjab is under assured irrigation, with three-fourths of it irrigated by groundwater resources. This has led to a decline in the water table and overexploitation of groundwater resources. The situation has worsened over time as the number of dark blocks has almost doubled since the early 1980s (Table 1).

Table 1: Trends in over-exploitation of groundwater resources in various blocks of punjab

Category of exploitation Year/Number of blocks
1984 1989 1999 2004 2011
Dark (over-exploited) 53 62 73 103 110
Dark (critical) 7 7 11 5 4
Grey (semi-critical) 22 20 16 4 2
White (safe) 36 29 38 25 22
Total number of blocks 118 118 138 137 138

The ever increasing demand-supply gap is visible from the declining availability of groundwater , from 0.30 ha m in 1984 to 0.03 ha m in 1999, turning negative to the tune of 1.48 million ha m in 2011 as indicated in Figure 1.

Given the increasing intensification of agriculture and overexploitation of groundwater resources, it was necessary to undertake a timely action to reverse groundwater depletion in Punjab and promote the sustainable use of groundwater resources. To end this reckless and injudicious use of groundwater, irrigation scheduling was explored.

The Centers for International Projects Trust (CIPT) India, Punjab Agricultural University (PAU ), India and Columbia Water Centre, Columbia University, USA partnered in 2009 to promote innovations for reversing groundwater depletion in Punjab, as part of which the present project was conducted.

International Development Research Centre (IDRC), Canada: Provided support in 2012 under the project ‘Improving Food and Livelihood Security in Punjab through Water-Energy-Agriculture Management under Climate Change and Variability.’

United States Agency for International Development (USAID): Provided support under the project ‘Water Agriculture and Livelihood Security in India’ to scale up the tensiometer technology.

Farmer community: Key stakeholders in this initiative as they were the first-hand users of tensiometers in their fields.

Agricultural Insurance Company of India Limited (AIC): Supported promotion of tensiometers by providing innovative insurance product to farmers.

APPROACH AND METHODOLOGY

In order to promote water conservation among the farmers of Punjab, Tensiometer as a tool for scheduling irrigation in rice was promoted. The idea behind the use of Tensiometer is that if the indicated soil moisture is below what the plant needs to grow, there is need to apply irrigation water, otherwise not. Such irrigation scheduling can reduce water use in a crop because often farmers over irrigate the crop irrespective of its requirement especially when water and power to pump out water is free of cost. A simple approach was undertaken to widen the adoption of this device.

Identification of intervention areas followed by spreading awareness at farmers’ cooperatives through training camps along with identifying potential users. Farmers, as well as field workers, were recruited and trained on the use and installation of tensiometer on the fields. Post installation, regular monitoring, and data collection were also ensured on a timely basis. Hence, this collected information was then processed to estimate the impact of tensiometer on water and energy use.

A BRIEF DESCRIPTION OF THE TENSIOMETER

Screenshot (3)

A tensiometer is a simple device which guides farmers in the optimal use of water in irrigation by assisting in scheduling irrigation. It is designed to measure soil moisture. The structure of tensiometer consists of a porous ceramic cup, connected through a rigid, body tube to a vacuum chamber. All the components are filled with water. The body tube is transparent so that water within the tensiometer can be easily seen. The tensiometer is placed in the field with the ceramic cup in the soil in the plant root zone. The ceramic cup is porous so that water can move through it to equilibrate with the soil water. Evidence suggested that irrigation scheduling through tensiometer on one acre of rice helped in reducing the water use by 5,38,179 litres in 2012 and by 3,72,042 litres in 2013, without any compromise on yield. The water savings led to a reduction in power consumption as electric motors were used for lesser hours. The use of tensiometer helped in reducing the power consumption by 101 kwh/ acre in 2012 and by 70 kwh/acre in 2013. Therefore tensiometers were promoted amongst farmers so as to enhance the efficiency of water use in the cultivation of rice, one of the most water-intensive crops. Within a span of 4 years, 2010 to 2014, some 11,343 tensiometers were installed, mainly in the central Punjab, where the groundwater level had depleted relatively faster from 4.5 metres in 1973 to 14 metres in 2005.

INNOVATIVE INSURANCE PRODUCT

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To promote and popularize the use of tensiometers, an innovative approach was used. An insurance product was developed with the help of Agricultural Insurance Company of India Limited (AIC), which provides insurance coverage to farmers for the loss of yield due to use of this low-cost technology. Insurance played an important role in boosting the adoption rate of technology which was designed to benefit the farming community through conservation of natural resources. In 2014, the rate of adoption of tensiometers for the insured farmers was 70.2 %, as compared to 26.5 % by non-insured farmers. In addition, awareness and training camps were organized for the farmers and the field staff, where they were trained on the installation, use, and maintenance of tensiometers. CIPT field workers regularly visited the site to ensure smooth functioning.

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Story Submitted by Dr. Kamal Vatta and Garima Taneja from Centers for International Projects Trust

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