种植年限对果园土壤团聚体分布与稳定性的影响

Effect of Different Cultivation Years on Composition and Stability of Soil Aggregate Fractions in Orchard

用干筛法和湿筛法研究了延边地区典型地域不同种植年限果园土壤团聚体的分布特征及其稳定性。结果表明：果园土壤〉10mm大团聚体含量和0．25～10mm团聚体含量均随着种植年限显著增加，年增长分别为1．28％，0．078％；种植60年时0．25～10mm粒级体所占比例由荒地的80．92％增加到88．10％，分形维数随种植年限延长而减小，而明显小于荒地土壤，减小幅度为7．73％。土壤平均重量直径（MWD）和几何平均直径（GMD）呈现逐年增大，年增长分别为0．76％，1．10％。〉0．25mm水稳性团聚体含量随着种植年限逐年增加，种植60年时，较荒地增加44．31％，年均增长0．74％；水稳性团聚体的分形维数逐年减小趋势，种植60年时较荒地下降4．65％；水稳性MWD与GMD均明显大于荒地，且随着种植年限的增加而逐年增大，GMD在种植60年时较荒地增加63．71％；可蚀性K值随着种植年限延长逐年减小，种植60年时较荒地减小25．05％。果园土壤〉5mm，〉1mm，〉0．5mm，〉0．25mm粒级的团聚体破坏率均大于荒地；〉0．25mm团聚体破坏率逐年减小，种植60年时的团聚体破坏率较荒地减小36．55％，果园土壤容重随着种植年限的延长逐年减小，种植60年时较荒地下降14．29％。果园土壤结构随种植年限增加日趋稳定，增强了抗侵蚀能力。

In order to evaluate the effects of different cultivation years on the composition and stability of soil aggregates. Aggregates of soils in apple-pear orchard of Yanbian region, Jilin province with the dry-sieving method and the wet-sieving method for comparison. The results showed that： Under the condition of dry sieve, ）10 mm and 0. 25 - 10 mm air dry aggregates of orchards soils increased continuously with the cultivation years. Average annual growth rate was 1.28%, 0. 078%. The contents of 0.25-10 mm increased from 80.92% in uncultivated soils near the orchard to 88. 10% in the orchard soils in the 60th year. The fractal dimension（D） of orchards soils decreased continuously with the cultivation years, and it was lower than that of uncultivated soils near the orchard. And it decreased by 7.73 % in the 60th year compared with uncultivated soils near the orchard. The mean weight diameter （MWD） and the geometric mean diameter （GMD） of orchards soils increased continuously with the cultivation years. Average annual growth rate was 0.76%, 1.10%. Under the condition of wet sieve, the contents of 〉0.25 mm water-stable aggregates of orchards soils increased continuously with the cultivation years. And it increased by 44.31% in the 60th year compared with uncultivated soils near the orchard. Average annual growth rate was 0. 74%. The fractal dimension（D） of orchards soils decreased continuously with the cultivation years. In the 60th year, it decreased by 4.65%compared with uncultivated soils near the orchard. The mean weight diameter（MWD） and the geometric mean diameter（GMD） of orchards soils increased continuously with the cultivation years and it was higher than that of uncultivated soils near the orchard. GMD increased by 63.71% in the 60th year compared with uncultivated soils near the orchard. The erodibility K value of the orchard soils decreased with the cultivation years, and it decreased by 25.05% compared with uncultivated soils near the orchard. In the orchard soils, the aggregate destruction rate of 〉5 mm, 〉1 mm, ）0.5 mm, 〉0.25 mm were higher than uncultivated soils near the orchard. Aggregate destruction rate of 〉 0. 25 mm decreased with the cultivation years. In the 60th year, it decreased by 36. 55〉 compared with uncultivated soils near the orchard. The soil dry bulk density of orchards soils decreased with the cultivation years. And it decreased by 14.29 〉if0 in the 60th year compared with uncultivated soils near the orchard. Soil structure stability in orchard increased with increasing cultivation years. Thus, soil erosion resistance was enhanced.