Effects of applying byproduct from flue gas desulfurization in batches on sodic soils quality and sunflower growth

In order to study the application mode of By-product from Flue Gas Desulfurization (BFGD) used to reclaim sodic soils, the field plot experiment of sunflower was conducted to analyze effects of two application modes, applying BFGD in batches and applying BFGD only once, on the physical and chemical properties of two sodic soils (in sodic soil I, ESP=19.8; in sodic soil II, ESP=46.9) and the sunflower production. The results indicated that ESP and pH of the top 40cm soil decreased significantly, and germination rate, dry matter weight and sunflower production increased after applying BFGD in all the treatments. The soil EC in the top 40 cm soil appreciably increased in initial stage after applying BFGD. However, it was lower after two years than that in initial stage and soil EC was less than, or close to the value before the experiment. The mode of applying BFGD in batches was better than that of applying it only once because the mode of applying BFGD in batches could decrease the accumulation of soil salts and promote the dissolution of CaSO4. The ESP of sodic soil I and sodic soil II reduced to 13.5 and 14.9 respectively, their pH reduced to 8 and 8.4 respectively, and sunflower production increased by 1630.80 kg·hm⁻² and 1315.65 kg·hm⁻² respectively in the most effective treatments of applying BFGD in batches. In contrast to the mode of applying BFGD only once, the soil pH decreased by 4.76% and 2.33% in sodic soil I and sodic soil II, ESP decreased by 8.78% and 24.75%, germination rate increased by 4.71% and 17.57% and sunflower production increased by 12.95% and 17.52%. If the drainage was in good condition and the byproduct was applied at right rate, the salts of soil top layer would not be accumulated.