秸秆生物炭对草原矿区重构土苜蓿生长状况的影响

Effects of straw biochar on the growth of Medicago falcata in the reconstructed soil of grassland mining area

表土稀缺和土壤贫瘠是制约草原矿区生态修复的重要因素,生物炭作为提高土壤质量、促进作物生长的有效手段已被广泛证实,但对于重构土植被生长状况影响的研究较少。以内蒙古草原矿区表土(T)、煤矸石(C)、岩土剥离物(W)及粉煤灰(F)等材料重构的五种表层土壤为研究对象,材料配比分别为T=1(D1)、T∶C∶W∶F=2∶1∶6∶1(H3)、T∶C∶W=2∶2∶1(H10)、T∶C∶W=3∶3∶4(H11)、T∶F=2∶3(H15),分析了不同热解温度(300℃、400℃和500℃)、不同施用量(0、6、12和24 g/盆,即0、7.5、15和30 t/hm^(2))的秸秆生物炭对重构土苜蓿生长状况的影响。结果表明:1)秸秆生物炭对原表土和重构土壤的苜蓿出苗均存在不同程度的抑制作用,而对于苜蓿株高、叶面积及地上生物量基本呈现正激发效应。2)促进几类重构土苜蓿生长的生物炭最佳处理方式分别为D1\H3\H10-500-24(30 t/hm^(2))、H11-400-6(7.5 t/hm^(2))、H15-500-12(15 t/hm^(2)),并非生物炭热解温度和施用量越高对苜蓿改良的效果越好。3)在相同生物炭处理下,因重构表层土壤理化性质的异质性,秸秆生物炭对苜蓿苗期生长的影响程度不同,重构土苜蓿出苗率和地上生物量均难以超越原表土水平,而苜蓿株高和叶面积可达到原表土水平。

In the grassland mining area,the scarcity and barrenness of topsoil are the important factors restricting the ecological restoration.Biochar,as an effective means to improve the quality of soil and promote the growth of crops,has been widely confirmed,but there are few studies on the effects of the growth of vegetation on the reconstructed soil.In this study,we used topsoil(T),coal refuse(C),waste rock and soil(W),and fly ash(F)of Inner Mongolia grassland mining area to reconstruct five kinds of surface soil,and material ratio is T=1(D1),T∶C∶W∶F=2∶1∶6∶1(H3),T∶C∶W=2∶2∶1(H10),T∶C∶W=3∶3∶4(H11),and T∶F=2∶3(H15),respectively.The effects of straw biochar at different pyrolysis temperatures(300℃,400℃,and 500℃)and different application rates(0,6,12 and 24 g/pot,namely 0,7.5,15 and 30 t/hm^(2))on the growth of Medicago falcata were analyzed.The results showed that:1)straw biochar had different degrees of inhibition on emergence of Medicago falcata in both original topsoil and the reconstructed soil,but showed positive excitation effects on plant height,leaf area and aboveground biomass.2)For the reconstructed surface soil,the best treatment of biochar to promote the growth of Medicago falcata is D1\H3\H10-500-24(30 t/hm^(2)),H11-400-6(7.5 t/hm^(2)),and H15-500-12(15 t/hm^(2)),respectively.It is not that the higher the pyrolysis temperature and application rates of biochar,the better the effects of Medicago falcata improvement.3)Under the same biochar treatment,straw biochar had different effects on the growth of Medicago falcata at seedling stage due to the heterogeneity of the physicochemical properties of the reconstructed surface soil.The emergence rate and aboveground biomass of Medicago falcata in the reconstructed soil could hardly exceed those in the original topsoil,while the plant height and leaf area of that could reach those in the original topsoil.