Abstract
Along with the rising popularity of introducing large scale machinery into the field and the decrease in opportunities for tilling deeper soil due to the wider adoption of rotary tillage, it is now recognized that favorable planting circumstances in the field are diminishing as hard strata form in the subsoil directly below the cultivated surface soil.
This paper describes several findings from a field investigation concerning the intake rate test of cumulative infiltration under several experimental combinations using a rotary tiller and subsoil breaker with a chisel type subsoiler.
The results of the test are as follows:
1) Cumulative infiltration was greater once the soil was disturbed by a chisel type subsoiler, due to a decrease in soil hardness.
2) Cumulative infiltration by the experimental apparatus was initially less than that of the chisel type subsoiler. At 203 days after subsoil breaking, however, cumulative infiltration by the ex-perimental apparatus became grea-ter than that of the chisel type subsoiler.
3) A regression analysis was carried out on the two factor of subsoil breaking area and subsoil breaking depth for a 20 minute period of cumulative infiltration. The result was that the correlation coefficient of the subsoil breaking depth was higher than that of the subsoil breaking area.
4) The regression equation for the 20 minute cumulative infiltration and the subsoil breaking depth exceeded the 1% level of significance at 22 days, and 203 days after subsoil breaking. This demonstrates the influence of the subsoil breaking depth on cumulative infiltration.
5) At subsoil breaking depths greater than 0.3m, cumulative infiltration increased along with the water supply and this effect remained up until the 203 days.
