By the fertilizing experiment on the sand hill, it was observed that the loss of plant nutrients by leaching has a pronounced effect on the yield. So, we carried out experiment upon the leaching of NH^+_4 by laboratory work. The results are summerized as follows:
Two kinds of sandy soils were used in this investigation-jinzai sandy soil of the low productivity and Tomimasu sandy soil of the high productivity. Each of these soils was filled in a cylinder of 7cm diameter and 70cm length, and ammonium sulphate was added upon the soils. Pouring water 100cc. 300cc, 600cc upon the soil, NH^+_4 absorbed in each horizon was analized, but there was not so difference between the two soils.
Various fertilizers were tested by the same method, but no remarkable fact was found. By another experiment, it was found that NH^+_4 from ammonium carbonate was much absorbed by the soil, but from amm. phosphate and amm. sulphate was not so much. The pH difference of the soil solution did not affect to the NH^+_4 absorption of the soil.
When the soil contained much <ca>^<++>, the absor bed NH^+_4 by replacement became little.