Effects of subsoil bulk density on root growth and soil enzyme activities during the growth of corn(Zea mays L.)

The two-year pool-culture and barrel-culture experiments were conducted to study the impacts of subsoil bulk density on root lenght,root dry weight,soil enzyme activities and yield in corn field on a sandy loam soil at the Experimental Farm of Henan Agricultural University.The results showed that the dynamic changes of root length,root dry weight,soil catalase,invertase,protease,urease,alkaline phosphatase activities and yields were single curve during the growth of corn,and the maximum values of these parameters occurred at the corn silking stage.Root length,root dry weight,yield and its components decreased with increaseing soil bulk density.These enzyme activities decreased with the increasing of both soil bulk density and soil depth.The higher the soil bulk density was the less active the soil enzyme activities were all soil enzyme activities were significantly different among soil bulk densities in the same soil layer,and they were also affected by soil bulk density in the adjacent layers.The bigger the soil bulk density of adjacent layers was the more significant the decrease was.The effect of subsoil bulk density on soil enzyme was more apparant from jointing stage to maturity.