Innovative Solution

Water use efficiency, irrigation scheduling, supplemental irrigation, arid and semi-arid tropics

technical

Farmers in the developing countries usually  adapt calendar-based irrigation scheduling,resulting poor water use efficiency. Whereas the use of existing available tools/models for irrigation scheduling is limited to research organizations or in the large scale –farming systems due to complex parameterization and huge data requirement.  A simple and farmer friendly Water Impact Calculator (WIC),which aims to increase water use efficiency in agricultural systems has developed using data from strategic  research  through a desktop study.  Thus,this study focused on developing a simple decision making generic tool to decide the timing and quantity of water to be applied  that  will be useful for small and marginal farmers of the semi-arid tropics. Due to uncertainty in rainfall and site specific heterogeneity,crop water requirement changes from place to place. With minimum basic inputs,WIC develops irrigation scheduling (amount of water and date to be applied) for entire crop growth period well in advance.

The WIC developed in the present study has been tested at five experimental locations in the states ofGujarat,Rajasthan and Andhra Pradesh. Field experiments were conducted under two land-form conditions (BBF and Flat fields); and irrigation in those fields was applied by two different methods (drip and flood methods). Water balance made by WIC in these experimental sites showed that calendar based irrigation scheduling led to large amount of water loss generally due to over irrigation,resulting in poor water use efficiency. Results showed that number of irrigation and amount could be  reduced to 30-40 % using WIC based irrigation scheduling without compromising  crop yields. For further up-scaling,we propose that WIC could be linked with mobile technology. Farmers could provide essential data/information using their cell phone; this information  is  processed online at computer server and outputs (message) will be returned back to farmers. 

WIC is a simple and excel based decision making tool for agricultural use. This tool holds potential for utilizing water resources better,especially in water scarce regions like arid and semi-arid tropics. This is a generic tool used for irrigation scheduling and identifying suitable cropping system. WIC could work with any kind of soil and crop types with minimum modifications. 

ICRISAT is conducting strategic research on natural resource management from the past 35 years.  Long- term strategic research data are available at both research station and farmer’s field/community level,which comprises biomass and grain yield,surface runoff,moisture content,soil loss,nutrient,weather and data pertaining to socio-economic conditions. Along with available data and understanding of the rainfed system,ICRISAT availed the  opportunity to work with the sustainable Agricultural Initiative (SAI)  on  a pilot study for developing,testing and validating a simple water impact calculator (WIC) to serve as a decision support tool for small and marginal farmers. SAI platform is an organization created by the food industry to communicate and to actively support the development of sustainable agriculture involving stakeholders of the food chain. ICRISAT consortium with local NGOs and farmers has validated WIC in five locations in three  states ofindia: Rajasthan,Gujaratand Andhra Pradesh during the year 2010-11.

WIC  is tested at pilot sites by comparing simulated soil moisture status with observed data and a  good agreement was found in the predicted and observed results. This year,WIC  is  used to make entire irrigation scheduling in all the five locations under different crop types and soil condition. We are also looking to validate it in large scale irrigation projects in Karnataka,for enhancing water use efficiency and food production in canal command areas.

Despite the advancement in  technologies,instrumentation and decision software/tools,farmers in the semi-arid tropics still face  problems in  managing natural resources. Because  the available technology and decision making systems are limited mainly to  scientific community and for large scale farming community. Farmers in developing countries still have adapted calendar based irrigation scheduling resulting over irrigation or stress situations which lead to poor water use efficiency. The WIC is simple and farmers-friendly in terms of data requirement and  for estimating the water requirement of a particular crop grown in a particular soil type at a given location. Due to simplification,WIC further could be linked through mass communication tool such a cell phone for scaling up purposes.

Over irrigation in agriculture is a general tendency of farmers that leads to  nonproductive loss of water,  resulting  in poor water use efficiency. WIC does mass balance and define major principle hydrological components. Our primary results show that number of irrigation and amount could be  reduced to 30-40 %  by using WIC-based irrigation scheduling without compromising  crop yields.  . This enhances water use efficiency and reduces pumping time and power requirement.

Indicator: crop production and income; Intensifying agriculture,Cropping intensity

Indicator in large scale Irrigation projects: Upstream -downstream water availability,Equity and water allocation between head and tail end farmers in canal command area

WIC could potentially be used in both rainfed and irrigated farming systems.

Command Area Development Authority in Karnataka is looking forward to enhance water productivity in agriculture. Similarly,over irrigation,water logging,poor water use efficiency are  the major problems  in  most of the canal command areas and stakeholders in canal command areas could be the potential users. 

1. WIC needs very basic data as an input which users easily can provide. WIC is excel based decision tool and does not require any installation. One hour training/demonstration is sufficient enough to learn this tool.
2. Farmers generally do calendar-based irrigation scheduling resulting in low water-use efficiency. Irrigation scheduling in WIC is designed on scientific basis. It analyzes entire water balance on daily time scale for every centimeter soil grid and for entire 12 months period (generate matrix: time vs. depth). WIC suggests exact amount of water to irrigate on appropriate date for a given crop. Despite providing future recommendations of entire crop period on existing data base,WIC facilitate user to enter feed back of actual weather condition and water application practice on the ground. Based on such inputs it consistently keeps refine follow up recommendations.
3. WIC could be used together as simulation model and decision making calculator. It provides detailed mass balance components such as evaporation,transpiration,deep percolation,surface runoff and soil moisture status. Such information is useful in identifying blue and green water resources available in locality and could be useful for deciding appropriate crop plan for next season on community basis. Moreover model generated results could be further linked to identifying crop water stress and for estimating crop grain and biomass yields under various management scenarios (not yet defined in current version).
4. WIC  captures insitu and exsitu intervention and simulates field to micro-watershed scale hydrology. Watershed development programs inIndia  are running at the  national scale and have recommended  developing water balance analysis at least for one location in each district. With most of the available simulation models;  it has been  difficult to use them due to complex parameterization, but WIC seems  an appropriate tool that requires basic minimum data and has a quick run time. This will help in analyzing water related trade-offs at both upstream and downstream locations for different stakeholders.

This tool is being further  validated in pilot areas,and we are looking forward to scale up in follow up projects.

For further up-scaling,we propose that WIC could be linked with mobile technology. Farmers would be l  provided essential information using their cell phone; this information will be processed online at computer server,and outputs (message)   returned  to the farmers.

ICRISAT (International Crops Research Institute for the Semi-Arid Tropics),with its headquarters at Patancheru,Andhra Pradesh,India is one of the international institutes addressing the issues of rainfed agriculture for developing countries (55 countries) in the semi-arid tropics. ICRISAT’s mandate is to improve the livelihoods of the poor in semi-arid crop-livestock production systems through integrated genetic and natural resource management strategies. ICRISAT’s strategic focus in the semi-arid tropics is to attain impact by improving the livelihoods of smallholder farmers and their families through the application of quality science towards developmental goals.

Contact details: Dr. Suhas P. Wani,Principal Scientist,Resilient Dryland Systems,ICRISAT; Email: s.wani@cgiar.org