AGRICULTURAL RESEARCH COMMUNICATION CENTRE www.arccjournals.com *Corresponding author’s e-mail and address: amit.agron@gmail.com, Central Arid Zone Research Institute, Regional Research Station, Bikaner-334 006, Rajasthan, India. 1 IWLMP, Jordan. Indian J. Agric. Res., 53(4) 2019: 463-467 Print ISSN:0367-8245 / Online ISSN:0976-058X Evaluation of cropsyst model for yield and water productivity of chickpea Ramesh Kumar, R.S. Yadav, Amit Kumawat*, V.S. Rathore, N.D. Yadava and Vinay Nangia 1 College of Agriculture, Bikaner-334 006, Rajasthan, India. Received:12-01-2019 Accepted:16-04-2019 DOI: 10.18805/IJARe.A-5203 ABSTRACT An experiment entitled “Evaluation of CropSyst model for yield and water productivity of chickpea” was conducted on farmers field during rabi 2012-13 at village Mainawali in Hanumangarh district of Rajasthan. The soils of the area are alluvial and calcareous in nature formed under arid and semi arid climate. The soils of site are brown to grayish brown and dark gray in colour, besides being calcareous and slightly alkaline in reaction having 67.7, 11.1 and 21.0 % of sand, clay and silt, respectively in 0-15 cm soil depth with pH 8.09 and low soil organic matter content. The simulated and observed green area index differs with field measurements at all stages. The simulate yield of chickpea were closer to the observed yield. The total water applied in chickpea was 415 mm out of this 356.5 mm consumed in ET. Thus, ET constituted 86% of total water applied and deep drainage constituted 12% and rest 2% stored as residual soil moisture. Key words: Chickpea, CropSyst, Model, Simulation. INTRODUCTION Freshwater in sufficient quantity and adequate quality is a prerequisite for human societies and natural ecosystems (Costanza and Daly, 1992). Agriculture is the largest user of water with 65–75% of freshwater being currently used for irrigation (Bennett, 2000). Furthermore, the scarcity of water for agriculture are heightened by groundwater mining, escalating cost of developing new irrigation facilities, low water productivity of existing resources, increasing water pollution and degradation of water related ecosystems (Rosegrant et al., 2009). Water productivity, a concept expressing the value or benefit derived from the use of water, includes various aspects of water management and is very relevant for arid and semi- arid regions. It can be expressed in terms of grain (or seed) yield per amount of water used in different processes such as transpiration, evapotranspiration and percolation and provides a proper diagnosis of where and when water could be saved. Increasing water productivity is particularly appropriate where water is scarce compared with other resources involved in production. Rajasthan is predominantly a rainfed state and precipitation being major source of annual renewable water supply. The total water resources of state account for 45.09 BCM, consisting 33.94 BCM share by surface water resources and 11.15 BCM by groundwater resources. The overall utilization of water resources is 81 % being 71 % for surface water and 104 % of groundwater resources. With the fast increasing population the water availability in the state is decreasing at an alarming rate and water scarcity is growing rapidly. According to an estimate, in the year 2001, the annual per capita water availability was 840 m 3 and expected to be as low as 439 m 3 by 2050 (Vision 2004a, 2004b, X th Five Year Plan) (Kumar et al., 2016). The situation of groundwater resources is very critical in the state. Out of total 237 groundwater blocks of the state, the number of safe blocks reduced to 162 to only 32 from 1984 to 2004, whereas in the same period the numbers of dark blocks has increased from 22 to 140. At present ~ 80.4 % of groundwater blocks of state fall under category of dark and critical. Water scarcity threatens food security for millions of people particularly in the arid and semi-arid regions. A major constraint to increase the food grain production in arid Rajasthan is limited surface water availability. Furthermore, the current irrigation systems in Rajasthan State are causing environmental problems of rising and declining groundwater levels, water logging and salinization. The Hanumangarh district, located in the North Western part of Rajasthan State, represents the typical example of canal water misuse leading to rising groundwater levels, water logging and secondary salinization. These water management issues are very complex, and must be addressed by better planning and management. (Rathore et al., 2010). In order to improve water management and its productivity it needs to reveal the cause–effect relationships between hydrological variables such as evaporation, transpiration, percolation and biophysical variables such as dry matter and grain yields under different eco-hydrological conditions (Singh et al. 2006). Measurements of the required hydrological variables under field conditions are difficult, and need sophisticated instrumentation. Moreover, field experiments yielding site-specific information are very