Abstract
We investigated improvement methods and their effects on poorly drained Jaagaru soil which was resulting in reduced sugarcane production. The tilling capacity of the wide-chisel subsoiler tested was about two times higher than that of conventional plowing. The range of soil loosening reached to a depth of about 55 cm. The sugarcane yield was increased although the size of the soil clods produced by tilling and the germination ratio were almost same as those for the conventional process. The increase in sugarcane yield produced by subsoiling in Jaagaru fields after mechanical harvesting was about 10 %. It appears that the improvement in drainage properties was the main cause. The yield of sugarcane was increased by about 30 % through a combination of subsoiling and subsurface drainage even in Jaagaru soil with extremely poor drainage. However, no effect was observed by subsoiling alone. The cost of subsurface drainage using a trencher attached to a tractor was about 220,000 yen/10 a.
