Abstract
1) To know the changes of physical properties of the soil and those of productivities of fodder crops on upland field after it has been transposed from paddy field, more than ten kinds of summer annual fodder crops were tested in the field of Niigata Agricultural Experiment Station in 1961-1963, because such knowledges seemed to be indispensable foundations of introducing those crops to the field. 2) Taking adjacent ordinary upland field with similar soil properties as control, the crops were cultivated under the same cultivation methods, and growth and yield of the crops were measured, together with several physical properties of the soil and level of underground water. 3) Productivity of the transposed field compared with the ordinary one was shown in percentage of both yields of each crop. In general, the rate was lower in the first year of transposition, higher in the second year and again lower in the third. The reasons for these facts were attributed rather to the amount of rainfall during growing period of the crops, instead of the changes of poysical properties of the soil. That is, precipitation amounts of April-October in 1961 and 1963 were high but that in 1962 was very low. The transposed field used to have 30-40cm higher water head than usual field and gas phase of the former soil at -20〜-25cm from surface was very small showing mere 40%. Accordingly in a year with small rainfall and therefore not humid, high production was expected. 4) Exceptional cases were those root crops suchas fodder beet, Irish potato and sweet potato, which showed increasing production as years proceded after the transposition, suggesting the effects of changes of physical properties of the soil on these crops. 5) In ordinary paddy field, too high soil humidity by higher water head is inevitable. Particularly in heavy clay paddy, lower soil stratum was difficult to be improved, in short time, in its soil structure suitable to upland conditions. Therefore it is a fundamental necessity to make field dry postively by drainage in upheaving productivity of introduced fodder crop.
