大机械作业对黑土区耕地土壤结构性特征的影响

以东北典型黑土区耕地土壤为研究对象，通过对不同（大、中型）机械作业前后土壤硬度、容重和非毛管孔隙度/毛管孔隙度比值（NCP/CP）等结构性特征指标的测定和分析，研究了机械作业对土壤物理性质的影响.结果表明：机械作业后，土壤硬度在垂直梯度上均存在3个明显交替变化的层面，自上而下依次为耕作区、压实积累区和无影响区，中机械作业的土壤各层变化范围相对较浅，在17.5～30 cm范围内形成了新的土壤板结.大机械作业对黑土区耕地土壤结构性特征的影响以疏松作用为主，尤其对表层土壤的改良效果显著（P＜0.05），与收获前相比, 收获和深松作业后土壤容重分别降低了3.5%和7.2%，深松后NCP/CP提高了556.6%，这对增加入渗、削弱水土流失的潜在威胁极为有利；中机械作业则以压实作用为主.

Effects of heavy machinery operation on the structural characters of cultivated soils in black soil region of Northeast China.

With the cultivated soils in black soil region of Northeast China as test objects,this paper measured their structural characters such as soil strength,bulk density,and non-capillary porosity/capillary porosity(NCP/CP) ratio before and after heavy and medium-sized machinery operation,aimed to study the effects of machinery operation on the physical properties of test soils.The results showed that after machinery operation,there existed three distinct layers from top to bottom in the soil profiles,i.e.,plowed layer,cumulative compacted layer,and non-affected layer,according to the changes of soil strength.Under medium-sized machinery operation,these three layers were shallower,and there was a new plow pan at the depth between 17.5 and 30 cm.Heavy machinery operation had significant positive effects on the improvement of topsoil structure(P<0.05).After subsoiling and harvesting with heavy machinery,the bulk density of topsoil decreased by 7.2% and 3.5%,respectively,and NCP/CP increased by 556.6% after subsoiling,which would benefit water infiltration,reinforce water storage,and weaken the threat of soil erosion.The main action of heavy machinery operation was soil loosening,while that of medium-sized machinery operation was soil compacting.