Abstract
For the apple orchards in Aomori Prefecture, clover sod has been extensively used recently. The culture system is beneficial not only to the yield and the quality of the fruit, but also to the protection of soil erosion. The experimental results conducted on the soils of grass sod and ordinary plot may be summarized as follows:
The humus content and base exchange capacity are little higher in the sod plot soils than in the ordinary plot soils. But soil reaction is more acidic in the sod soils than in the ordinary plot soils, and on nitrogen, available phosphorus and potash contents no significant difference is found between the two soils.
On the microbial action studied, ammonification, nitrification, nitrogen fixation and cellulose decomposition in the sod plot soils are distinctly superior to those in the ordinary plot soils. Nitrification is the most distinct of the four.
On aggregate analysis the higher degree of aggregation is found in the sod plot soils than the ordinary plot soils.
The favourable effect of clover sod will be partly attributed to the above results.
