脱硫石膏对次生碱化盐土的改良效果

Reclamation of Secondary Alkaline Saline Soil with the Flue Gas Desulfurization Gypsum(FGDG)

由于土壤碱化引起物理性质恶化限制了土壤盐分淋洗,降低土壤交换性钠含量,提高土壤入渗率是决定碱化盐土能否改良成功的关键。通过油葵田间试验,探讨了脱硫石膏不同施用量(0、11.25、22.5、33.75、45 t/hm2)对次生碱化盐土的改良效果。结果表明:施用脱硫石膏可有效降低次生碱化盐土pH值、碱化度和总碱度,提高土壤入渗率,促进盐分离子淋洗。当脱硫石膏的施用量为11.25 t/hm2时,土壤pH值、碱化度和总碱度降低至8.20、7.66%和0.12 cmol/kg,并低于土壤发生碱化的临界指标,油葵成熟期株高、根长、单株干质量和产量分别达到74 cm、18.6 cm、57.6 g和1 077.0 kg/hm2。脱硫石膏改良效果和其用量不呈正相关,脱硫石膏过量可增加土壤可溶性全盐含量,抑制油葵生长发育。脱硫石膏中的Hg、Pb、Cr、Cd等重金属元素含量低于我国相关标准要求及试验田土壤背景值,施用脱硫石膏不会引起土壤重金属元素总量变化。

Because bad physical property originated by soil alkalization confine soluble salts leaching out soil, it is crucial to decrease exchangeable sodium content and to improve soil infiltration velocity. A field experiment was conducted to study the effectiveness of different dosage of flue gas desulfurization gypsum（0,11.25,22.5,33.75,45t/ha） for reclaiming secondary alkaline saline soil. Results obtained revealed that pH value,exchangeable sodium percentage（ESP）,total al kalinity（TA） was significantly decreased and soil infiltration velocity was improved by applying the FGDG. Total dissolved salt（TDS）leaching was accelerated by applying the FGDG. When the amount of FGDG was 11.25kg/ha,pH value,ESP and TA in soilwas decrease by 8.20,7. 66 and 0. 12 cmol/kg,respectively, which was low than threshold of alkali soil,and the plant height,root length, dry weight per plant, yield of sunflower were 74 cm, 18.6 cm, 57.6 g, 1 077.0kg/ha, re spectively. However, the effect of reclamation did not have positive correlation with the amount of FGDG. Excessive application of FGD could increase TDS, which restrain the growth of sunflower. As,Hg,Pb,Cr,Cd and other heavy metal elements in FGDG was lower than China＇s rele vant standards and background value of experimental field soil. FGDG applied into the soil did not cause changes in the total heavy metals.