桂西北喀斯特地区典型土壤在不同筛分强度下团聚体的稳定性

采用AS 200筛分仪分析了不同有机碳含量下3种喀斯特典型土壤(红壤、棕色石灰土、黑色石灰土)的团聚体颗粒在不同筛分强度(1.5,2和2.5mm振幅)的分级特征。结果显示,3种土壤平均重量直径(MWD)从大到小为:黑色石灰土棕色石灰土红壤(p0.05)。随筛分强度由小到大,棕色石灰土和黑色石灰土的团聚体颗粒分级变化较小,红壤团聚体颗粒分级由大颗粒(8,8~5,5~2mm)团聚体为主逐渐变为中间粒径颗粒(5~2,2~1mm)。红壤团聚体结构最易被筛分过程破坏,其次是棕色石灰土,最后是黑色石灰土。研究表明石灰土团聚体机械稳定性强于红壤,且筛分强度直接影响团聚体分级结果。从团聚体聚合角度来看,喀斯特石灰土土壤稳定性较强。

Soil Aggregates Stability at Different Sieving Strength for Typical Soils in Karst Region of Northwest Guangxi Province

Soil aggregates of two karst soils(terra fusca and rendzina) and one zonal soil(red soil) with different soil organic carbon(SOC) contents were analyzed at 1.5, 2 and 2.5 mm sieving strength using AS200. Results show that the three soils, in order of decreasing mean soil weight diameter(MWD), were rendzina, terra fusca and red soil(p<0.05). With the change of sieving strength, particle size fractions of soil aggregates for terra fusca and rendzina were the same, while for red soil, the fraction changed from the dominance by large aggregates(>8, 8~5 and 5~2 mm) to middle sizes(5~2 and 2~1 mm). Red soil was the most easily destroyed soil, terra fusca was the second, and rendzina was the third, according to the mechanical classification. This implies that the mechanical stability of karst soil aggregates was better than that of red soil, and soil aggregate classification for the karst soils was directly affected by sieving strength. From the point of view of soil aggregates, the stability of the karst soils was stronger.