[A-GE30] Conservation and Restoration of Soil Environment at Terrestrial Surface

[AGE30-04] The effects of trenching and insertion of crop residue on infiltration and soil erosion in a farmland

*Kazutoshi Osawa¹, Yasushi Mori², Akira Hoshikawa (1.Utsunomiya University, 2.Graduate school of Environmental and Life Science, Okayama University)

Keywords:Soil erosion, Infiltration, Trenching, insertion of organic matter, Sugarcane, Okinawa

It has been recognized that dynamics of water and the associated materials such as sediment and nutrients are important to conserve ecosystem existing in a watershed. Among others, excess soil and nutrients transports toward the coastal zones and deposition on corals are one of the major environmental problems in Okinawa, Japan, in which agricultural area is the major source of sediment yield. In this study, we focused on effects of trenching and insertion of crop residue on infiltration and soil erosion in a sugarcane field.

In the term of fallow period, water discharge in the trenching plot was 69% smaller than that in the control plot because the rainwater was infiltrated at the trenches on the surface. However, sediment yield in the trenching plot increased 57% over that in the control prot because soil surface was distubed by subsoiler to make trenches.

In the term of cropping period, water discharge in the plot of trenching and insertion of crop residue was 39% smaller than that in the control plot. The effect of increasing infiltration was continued because trenches did not fill with soil due to insertion of crop residue. Sediment yield in the plot of trenching and insertion of crop residue decreased 64% over that in the control prot. Then, from the view of preventing soil erosion, trenching and insertion of crop residue are effective practice during cropping period.