割草机对苜蓿地土壤压实的试验研究

用纽荷兰HW320自走式割草压扁机压地1～10次，测定不同压实次数、不同深度土壤体积密度、硬度、孔隙度、三相比、透水性等指标的变化及其每次压实后苜蓿产量的变化。结果表明：割草机压实对苜蓿地土壤结构参数影响显著；碾压次数越多，影响程度越大；割草机主要使0～30 cm土层的土壤结构产生压实；对透水性影响最为敏感；压实导致苜蓿减产，10次压实使每公顷苜蓿年损失干草4464 kg。

Experimental research on alfalfa soil compaction by mowing machine

Field tests were carried out using New Holland HW320 Self-Propelled windrower on alfalfa soil during clover harvesting in order to check the compacting effects and the alfalfa yield changes resulted from one to ten passes of the mowing machine along the same track. Then the changes of the soil bulk density, soil hardness, under different passes and different depths were measured and porosity, three phases of soil were calculated. And the changes of alfalfa yield after different passes were measured. The results indicate that soil compaction makes alfalfa soil condition change remarkably, all parameters were influenced by mowing machine. The more the number of tyre passes, the higher compaction degree; mowing machine caused the changes of soil structure from 0 to 30 cm depth mainly; water permeability is the most one of sensitive factors, only six passes can cause saturated hydraulic conductivity of water reaching zero. As a result of that soil compaction caused by mowing machine can influence the alfalfa yield and the decrease of alfalfa yield is 4464 kg/hm² annually after ten passes as compared to the alfalfa yield of growth in the original field soil.