煤矸石对盐碱土壤理化性质的改良效果

盐碱土壤物理结构差,植物成活率低,煤矸石具有改善盐碱土壤物理结构和化学性质的潜力,将煤矸石应用于盐碱地,能够达到煤矸石废弃资源循环利用和盐碱地改良的双重效果。为阐明煤矸石对盐碱土壤的改良效果和对土壤物理化学性质的影响,将不同用量(0、10%、20%、30%、40%、50%)和不同粒径(小粒径<1 mm、中粒径1—5 mm、大粒径>5 mm以及小中大等比例混合粒径)煤矸石施用于盐碱土壤,通过紫花苜蓿(Medicago sativa)盆栽试验,测定土壤的物理化学性质。结果表明,随着煤矸石用量的增加,紫花苜蓿株高和生物量呈现先增后减的趋势,20%用量煤矸石处理的株高和生物量分别比对照平均提高了21.45%和25.89%;团聚体平均重量直径(MWD)呈现先减后增再减的趋势;土壤饱和含水量、田间持水量呈现先稳定后降低的趋势;土壤EC值、pH值、碱解氮含量呈现持续降低的趋势,其中20%用量煤矸石处理的土壤pH比对照平均下降了0.51个pH单位;土壤总碳、总氮、总磷、有效磷含量呈现持续上升的趋势。从粒径角度考虑,对土壤EC、pH降幅以及团聚体含量、总养分、速效养分含量,小粒径>混合粒径≈中粒径>大粒径。土壤综合指数(SQI)随煤矸石用量增加先升后降;各粒径煤矸石处理下的SQI峰值大小表现为小粒径>混合粒径>中粒径>大粒径;20%用量下小粒径和混合粒径煤矸石处理的土壤SQI最高,分别比对照显著提高了68.27%和57.13%。综上,煤矸石可以改良盐碱土壤质量,促进植物生长,20%用量的小粒径和混合粒径煤矸石效果最好。

Amelioration Effect of Coal Gangue on Physical and Chemical Properties of Saline-alkaline Soil

The saline-alkaline soil has poor physical structure and low plant survival rate.Coal gangue has the potential to improve the physical structure and chemical properties of saline-alkali soil.Applying coal gangue to saline-alkali land can achieve the dual effects of recycling of waste coal gangue resources and improvement of saline-alkali land.In order to clarify the effect of coal gangue on the improvement of saline-alkali soil and the influence on the physical and chemical properties of soil,the alfalfa(Medicago sativa)pot experiment was conducted.Coal gangues with different application rates(0,10%,20%,30%,40%,50%)and different particle sizes(small-size of<1 mm,medium-size of 1–5 mm,large-size of>5 mm,mixed-size)were applied to an saline-alkaline soil,and the soil physical and chemical properties were determined.The results showed that with the increase of the amount of coal gangue,the alfafa height and biomass increased first and then decreased.The plant height and biomass under 20%coal gangue treatment were increased by 21.45%and 25.89%respectively compared with the control.Aggregate MWD of saline alkaline soil decreased first,then increased,and decreased at last.Soil saturated water content and field water holding capacity showed a trend of first stable and then decreasing.Soil conductivity,pH value,and alkali nitrogen content continue to decrease.The soil pH under 20%coal gangue was decreased by 0.51 pH unit on average compared with the control.Soil total organic carbon,total nitrogen,total phosphorus and available phosphorus in the soil showed a rising trend.Soil available potassium remained basically unchanged.From perspective of soil EC,pH value decreasing range and aggregate,total nutrients,available nutrients contents,different particle sizes could be ranked as small size>mixed size≈medium size>big size.Soil quality index(SQI)first rose and then decreased with the increase of coal gangue.The peak value of SQI under the treatment of coal gangue with different particle sizes could be ranked as small size>mixed size>medium size>big size.Soil SQI under treatments of coal gangue with small and mixed particle size was the highest under 20%dosage,which were significantly enhanced by 68.27%and 57.13%compared to the control,respectively.In general,coal gangue could improve the physical and chemical properties of saline-alkali soil,promote plant growth,and the small particle size and mixed particle size coal gangue with amount of 20%?30%had the best amelioration effect.