Spatio-temporal variations of soil moisture and salinity and their effects on cotton growth in a mulched drip irrigation field*

Experiments were carried out to study the dynamics of soil moisture and salinity and the effect factors on cotton growth in the Xinjiang Uygur Autonomous Region of China in 2012 and 2013. Regular soil samples, germination rate, plant height and cotton yield rate were surveyed during the growing stage. Soil moisture and salinity in the inter-film zone (IFZ) and near tape zone (NTZ) began to vary in mid-April. The water content and salinity were lower in the IFZ and NTZ respectively, and the differences reached a significant level limited to the upper 5 cm layer of the soil. However, the difference increased from June to September, when drip irrigation was used and transpiration was enhanced. Spatial standard deviations of soil moisture and salinity increased with the relevant spatial mean, and the spatial variation of soil salinity was higher in the NTZ than in the IFZ after elution and evaporation of the growing seasons. Pearson correlation tests showed that soils with higher soil moisture, lower salinity and more fine particles were generally favourable for cotton growth and production, while germination rate and plant height were mainly influenced by soil properties in the upper 20 cm of soil. Cotton yield could be influenced by soil properties from 50 to 80 cm below the top surface. (c) 2020 John Wiley & Sons, Ltd.