Abstract
For the purpose of clearing up the effects of clover rotation on the chemical and physical properties of field soil, this study was carried out. The results obtained are as follows: 1) Short term rotation of clover increased humus content remarkably and adjusted the soil reaction in surface soil compared with the common cropping system (growing wheat and sweet potato alternately). 2) Formation of water stable soil aggregates was promoted remarkably by clover rotation, particularly that of larger aggregates as 3.0 mm < diameter. 3) It seems that "Summer withering" of clover may be caused by the dry condition, under which clover cultivation reduced liquid phase of surface soil and produced so much hard greater clods in subsoil.
