Agro-ecological zoning using crop growth simulation models: characterization of wheat environments of India

Abstract

The main objectives of agro-ecological zoning are data inventory of environmental resources, identification of homologous environments, determination of agrieultural potential of a region, planning for regional development and identification of research priorities. Conventional methods employed are overlaying of maps and various statistical techniques. The major quantitative output of these approaches is growing period calculated from rainfall and potential evapotranspiration. In today's agriculture, when vast areas are irrigated and multiple cropping is practieed, growing period does not necessarily relate with productivity. Crop growth simulation models provide an alternative method for agro-ecological characterization of a region. These models integrate the effect of dynamic climatic, edaphic and crop management factors in determining grain yield. Coupled with a suitable Geographical Information System (GIS), crop simulation models can be used for determining agricultural potential of a region and to identify major constraints limiting productivity. A case study is described where a well validated model, WTGROWS, has been used to determine productivity of wheat at different locations in India as determined by climate and limited by water availability. Regions with similar productivity have been demarcated with a GIS. Effect of climatic variability on wheat yields is described. The model has also been used to identify shift in wheat productivity zones in a climate change scenario.