At the foot of Mt.Sanbe, Shimane-ken, barley is cultivated by irrigation without any fertilizers.
This study was carried out to make it clear why barley can grow only by irrigation. The results of the experiments are summerized as follows :
(1) By irrigation the underground temperature rose higher during the hours of 22～6 o'clock and the difference of temperature between irrigated and unirrigated plots was 5℃ in the coldest season.
(2) The irrigated soil showed lower acidity and contained a smaller amount of humus and nitrogen compared with the unirrigated, but a larger amount of absorbed bases.
(3) The irrigative water was alkaline and contained a larger amount of P_2O_5, CaO, <Fe>_2O3, as compared with other water.
(4) By pot and field experiments, it was confirmed that on any soil, barley can grow better by irrigation than by non-irrigation.
(5) pH and Eh of the irrigated soil were greater than that of the unirrigated soil.
(6) By irrigation NH_3-N contained in the soil remained changeless, but NO_3-N became less.