不同播种方式草本植物土壤团聚体特征及对根系固土力的影响

Effcets of Different Sowing Patterns of Herbs on Soil Aggregates Characteristics and Consolidating Soil Ability of Roots

为明确不同播种方式草本植物的土壤团聚体特征与根系固土力之间的关系,对素土、单播紫花苜蓿、单播非洲狗尾草和混播紫花苜蓿+非洲狗尾草4个处理进行无侧限抗压强度试验,采用干筛法和湿筛法测定土壤团聚体组成并对团聚体特征进行了定量分析。结果表明:(1)种植草本植物有利于小团聚体向大团聚体转化,混播优于单播。(2)种草处理的机械稳定性和水稳定性大团聚体含量R_(0.25)极显著大于素土,分形维数D_(d)正好相反(p<0.01),种植草本植物能够提高土体的大团聚体含量,降低土壤的分形维数,混播优于单播。(3)4个处理的平均重量直径MWD、几何平均直径GMD、大团聚体含量R_(0.25)与黏聚力呈正相关性,分形维数D_(d)呈负相关性;不同播种方式的分形维数D_(d)与黏聚力的相关性最好,其次是R_(0.25)。混播的机械稳定性和水稳定性团聚体分形维数D_(d)均呈极显著性相关(p<0.01),混播改变了土壤的团粒结构,分形维数对于土体黏聚力的贡献最大。种植草本植物能提高土壤大团聚体含量,降低土壤分形维数,对根系的固土能力起到促进作用,且混播优于单播。

In order to clarify the relationship between soil aggregate characteristics and consolidating soil capacity of herbs under different sowing patterns,unconfined compressive strength tests were carried out in four treatments:plain soil,single sowing of Medicago sativa L.,single sowing of Setaria anceps Stapf ex Massey L.and mixed sowing of Medicago sativa L.and Setaria anceps Stapf ex Massey L.The results showed that:(1)planting herbs was conducive to the transformation from small aggregates to large aggregates,and mixed sowing was better than single sowing;(2)the results showed that the mechanical stability and water stability macro-aggregate content(R_(0.25))of grass planting treatment were significantly higher than those of plain soil,and the fractal dimension(D_(d))was the opposite(p<0.01);planting herbs could increase the content of macro-aggregate in soil,reduce the fractal dimension of soil,and mixed sowing was better than single sowing;(3)the mean weight diameter(MWD),geometric mean diameter(GMD)and macro-aggregate content(R_(0.25))were positively correlated with cohesion,while fractal dimension(D_(d))was negatively correlated with cohesion;the fractal dimension(D_(d))of different sowing patterns had the best correlation with cohesion,followed by(R_(0.25));the fractal dimension(D_(d))of mixed sowing had significant correlation with mechanical stability and water stability(p<0.01);mixed sowing changed the soil aggregate structure,and the fractal dimension had the greatest contribution to the soil cohesion.Planting herbs can increase the content of soil macroaggregates,reduce the fractal dimension of soil,and promote the consolidating soil ability of root system,and mixed sowing is better than single sowing.