Effects of applying flue gas desulfurization gypsum and humic acid on soil physicochemical properties and rapeseed yield of a saline-sodic cropland in the eastern coastal area of China

Abstract

Soil salinization is considered as the most important abiotic stress limiting crop production and degrading soil properties. The purpose of this study was to investigate the effects of applied flue gas desulfurization (FGD) gypsum and humic acid on the amelioration of coastal saline-sodic soil and their influence on rapeseed yield. A 3-year field experiment was carried out in a saline-sodic soil at a farmer’s field in coastal area of north Jiangsu Province, China. The soil texture is sandy1 clay loam and the FGD gypsum requirement (FGR) is 6.40 t ha−1. The saline-sodic farmland was amended with FGD gypsum at rates of 0, 1.6 t ha−1, and 3.2 t ha−1 alone or combined with humic acid (1.50 t ha−1) compared with control. The FGD gypsum and humic acid were applied every year before rape growth. Compared with control, the concurrent application of FGD gypsum with humic acid decreased soil pH, sodium adsorption ratio (SAR), and exchangeable sodium percentage (ESP), and increased the soil electrical conductivity (ECe) and saturated hydraulic conductivity (K s). The yield of rapeseed was increased with the reduction of sodium adsorption ratio. The application of FGD gypsum increased the rapeseed yield. Humic acid incorporated into FGD gypsum enhanced the salt tolerance and resulted in the highest rapeseed yield. Pods per plant, seeds per pod, and 1000 seeds weight were also improved with the incorporation of humic acid. This study illustrated the benefits of applying FGD gypsum and humic acid for improving the physical and chemical properties of soil and increasing the productivity of rapeseed yield, and suggested a great potential for amending saline-sodic croplands using a combined amendment of FGD gypsum with humic acid.