Temporal and spatial changes in crop water use efficiency in central Asia from 1960 to 2016

Abstract

Water resources among five Central Asian countries are distributed unevenly. Since the collapse of the Soviet Union, the conflict between water and land use has become increasingly serious. Due to limited data, the temporal and spatial characteristics and trends of crop water use efficiency in Central Asia over the past 60 years remain unclear. This paper combines state-level agricultural statistics data and cultivated land data (1975, 2005 and 2015) from remote sensing imagery and calculates crop water use efficiency based on the FAO crop coefficient method. The results are as follows: (1) the development of crop cultivation in Central Asia is divided into an expansion period (1960-1990), a reduction period (1990-2000), and a recovery period (2000-2016); (2) the grain yield in Central Asia increased from 0.9 to 1.9 t/ha during 1960-2016, with Uzbekistan having the highest, reaching 4.2 t/ha in 2016. Cotton yield increased during 1960-1990 and decreased from 1990 to 2016. (3) The grain water use efficiency in Central Asia increased from 0.22 kg/m3 to 0.39 kg/m3 during 1960-2016. The cotton water use efficiency increased from 0.23 kg/m3 to 0.30 kg/m3 during 1960-1990, has decreased since 1990, and is currently close to the 1960s level.