不同粒径土壤活性有机碳测定方法的探讨

Methods for determining labile orange matter in different sized soil particles of different soils

选择不同肥力的沙质栗钙土、潮褐土和草甸栗钙土三种土壤,采用干筛法对其进行处理,获得四种不同粒级的土壤,分别为:<0.15mm、0.15～0.25mm、0.25～0.50mm和0.5～1.0mm,用目前最常用的两种化学方法分别对不同粒级土壤活性有机碳进行了测定。结果表明:不同粒级土壤活性有机碳含量差异显著(P<0.05),并且土壤活性有机碳含量随粒级增大而降低,其大小顺次为:小于0.15mm土壤>0.15～0.25mm土壤>0.25～0.5mm土壤>0.5～1.0mm土壤;与KMnO4氧化法相比,0.2mol·L-1(1/6K2Cr2O7—1∶3H2SO4)氧化,130～140℃油浴煮沸5min测定土壤活性有机碳的方法结果稳定,重现性好,变异系数小,且时间短,适宜大批土壤样品活性有机碳的测定。

Sandy Chestnut Soil, Cinnamon Soil and Meadow Chestnut Soil, of which the fertility are low, medium, and high, respectively, were divided into four sized soil particles based on dry sieve analysis （〈 0.15 mm, 0.15-0.25 mm, 0.25-0.50 mm,0.5-1.0 mm）. Labile organic matter （LOM）, on each sized particle was determined using two most commonly used chemical oxidation methods. The results showed that LOM contents on each sized particle had significant differences, with the increase of soil size, LOM contents are decreasing. Method using 0.2 mol·L^-1 （ 1/6K2Cr2OT-1 ： 3H2SO4 ） to oxidative and boiled in oil bath for 5 minutes could be used as the basic method to determine soil LOM ,because it had some advantages such as stable results, good repeatable, smaller variance coefficient, shorter time（ only as short as 5 min）, and it was especially suitable for determining large quantities of soil samples.