Water use efficiency and benefit for typical planting modes of drip-irrigated cotton under film in Xinjiang

Abstract: Drip irrigation under film has been widely applied in cotton field of Xinjiang autonomous region, because of its significant advantages on saving water, raising soil temperature, decreasing soil salinity in root zone, and consequently increasing cotton yield. Under current field conditions of cotton production, choosing a suitable planting mode for drip irrigated cotton under film according to the local conditions of heat, radiation, soil and mechanization, is very important for adjusting the distribution of soil water and salt in field, advancing cotton growth, raising cotton yield and labor productivity, and increasing income of farmers. Total three typical planting modes of drip irrigated cotton under film, such as traditional mode, mechanical picking mode and super wide film mode, have been built up in Xinjiang autonomous region up to now. Based on planting density, irrigation quota, the distribution of soil water and salt in root zone, the width of plastic film and other factors impacting cotton production benefit, this study compared the three typical planting modes regarding water use efficiency and economic benefit by carrying out field investigation. Obvious difference in water use efficiency was found among the three typical planting modes because of the great difference in water consumption and yield, which might be caused by the specific planting density, irrigation quota, distribution of soil water and salt in root zone and width of plastic film for each planting mode. Water use efficiency for the super wide film mode was 1.04 kg/m3, and was much higher than 0.98 kg/m3 for the traditional mode and 0.89 kg/m3 for the mechanical picking mode. Moreover, economic benefit was greatly affected by both planting modes (influencing initial investments and cotton yield) and cotton-picking types (influencing cotton-picking cost and cotton price). The economic benefit for the super wide film mode topped with 18,582 yuan/hm2, and was slightly higher than that for the mechanical picking mode (18,298 yuan/hm2), while that for the traditional mode was the lowest with only 11,725 yuan/hm2. Therefore, in order to utilize agricultural water resource efficiently and increase income of planting cotton, the super wide film mode might be a good choice and was suggested to be widely promoted in Xinjiang autonomous region. However, some improvements should be made on the existing cotton pickers in order to bring about mechanization of cotton picking for the super wide film mode. Alternatively, adjusting the location of drip pipes for the mechanical picking mode (e.g. putting drip pipe in the middle of narrow row) might be a good choice, but the resulted water use efficiency and benefit should be further studied.