苏打型草甸碱土团聚体特征对长期有机培肥措施的响应

Response of soda-type meadow alkali soil aggregates to long-term organic fertilization

松嫩平原西部苏打草甸碱土具有碱性强、结构性差的特点。本研究以长期定位试验为基础,开展长期施用有机肥措施下苏打型草甸碱土团聚体特征的研究。根据有机肥施用年限,设置4个处理,分别为:施用有机肥5a(S5)、9a(S9)、12a(S12),以不施用有机肥作为对照(CK),每个处理重复3次,重点研究土壤水稳性团聚体分布特征、平均重量直径、几何平均直径、分形维数。结果表明:苏打草甸碱土经过有机培肥处理,大团聚体数量增加,小团聚体数量减少,有机培肥9a处理大团聚体含量(35.20%)最高;各有机培肥处理水稳性团聚体平均重量直径(27.54~54.22 mm)、几何平均直径(0.13~0.17 mm)均优于对照(13.48mm、0.08mm),分形维数(2.86~2.88)均小于对照(2.95),有机培肥9a处理土壤结构稳定性(平均重量直径54.22 mm、几何平均直径0.17 mm、分形维数2.86)最好;经回归分析,水稳性大团聚体含量与平均重量直径、几何平均直径呈正相关,与分形维数呈负相关。综合结果来看,有机培肥处理均促进了表层土壤大团聚体的形成,并提高了其结构稳定性,而有机培肥9a处理效果最好。

Sodic meadow alkaline soils in western Songnen Plain are characterized by strong alkaline and poor structure. Based on long-term location test,this study exploered the aggregate characteristics of soda-type meadow alkali soil under long-term application of organic fertilizer. According to the organic fertilizer application stage,4 treatment was set： organic treatment was performed for 5 years（ S5）,9 years（ S9）,12 years（ S12）,and treatment with no fertilizer was used as control（ CK）,each process was replicated for three times. Distribution characteristics of soil water stable aggregates,the average weight diameter,the geometric mean diameter and the fractal dimension were studied. The results showed that the number of large aggregates of soda meadow alkaline soil increased after organic fertilizer treatment,and the number of small aggregates decreased. The highest content（ 35.20%） of large aggregates was from treatment by organic fertilizer 9 years; The average weight diameter（ 27.54~ 54.22 mm） and geometric mean diameter（ 0.13 ~ 0.17 mm） of the water-stable aggregates were both higher than that of CK（ 13.48 mm、0.08 mm）. The fractal dimension（ 2.86 ~ 2.88） was lower than that of CK（ 2.95）,the best stability of soil structure（ average weight diameter 54.22 mm,geometric mean diameter 0.17 mm,fractal dimension2.86） was from 9 years＇ organic fertilization. The regression analysis showed that the content of water-stable macro aggregates was positively correlated with average weight diameter and geometric mean diameter,and negatively correlated with fractal dimension. We can conclude that organic fertilization treatment promoted the formation of large aggregates in the surface soil and improved its structural stability,and it was best after 9 years＇ organic fertilization.