不同开垦年限黑土耕地土壤导气率及其影响因素

为探讨开垦对典型黑土土壤导气率的影响,以未经开垦天然次生林(0 a)和开垦年限为17、30、40 a耕地土壤为研究对象,采用PL-300型土壤导气率测定仪测定耕作区0~20 cm土层水平、垂直2个方向的土壤导气率,并计算其各向异性。结果表明:土壤水平、垂直导气率均随开垦年限的增加而显著减少(p0.05);与未开垦天然次生林相比,土壤垂直导气率下降22.44%~95.44%,土壤水平导气率下降40.45%~92.50%;不同开垦年限土壤水平、垂直导气率均呈现出随土层的加深而降低的一致规律。不同开垦年限土壤导气率各向异性表现出随着开垦年限增加逐渐增大的趋势,并在30、40 a表现出显著性(p0.05)。土壤导气率与密度呈极显著负相关,与孔隙度、非毛管空隙度、有机质均呈极显著正相关。黑土土壤的气体传输能力随开垦年限逐渐降低,密度、孔隙度、非毛管空隙度、有机质均显著影响黑土土壤导气率。

Air Permeability and Its Influence Factors of Black Soil with Different Tillage Periods

The experiment was conducted to study the effect of tillage on soil air permeability of typical black soils for the farmlands with different tillage periods of 17, 30, 40a and no-tillage (natural secondary forest land).The air permeability of 0-20cm soil layer in both vertical and horizontal directions were measured by using PL-300 soil permeability tester, then the anisotropy of air permeability was calculated.The soil air permeability in both directions was decreased significantly with tillage periods increasing.Compared with natural secondary forest (0a), the air permeability was decreased by 22.44%-95.44% and 40.45%-92.50% in vertical and horizontal direction, respectively.The soil air permeability from different reclamation years showed the same trend in both directions, and the air permeability became lower with deepening the soil layers.The anisotropy of soil air permeability of different reclamation years was increased gradually with the increase of tillage time, and showed a significant change when tillage period was longer than 30a.The soil air permeability presented a significantly negative correlation with bulk density, and a significantly positive correlation with porosity, non-capillary porosity and organic matter.Therefore, the gas transport capacity of black soil gradually is decreased with tillage period, and the bulk density, porosity, non-capillary porosity and organic matter significantly affect air permeability of black soil.