6 
MANURING EXPERIMENTS WITH PADDY RICE. 
metres), was sunk several feet from its neighbour 1.5 foot into 
the soil projecting about 2 inches above the surface. As each 
plot had to be supplied with water that had not yet been used 
for the irrigation of others, a tub was placed on a small support 
on the northern side of each frame and furnished with a spout 
with a small opening through which the water was let in. A 
small notch in the side of the frame served as the outlet for 
waste water, but an overflow took place only rarely, in times 
of copious rain, because usually the surrounding not irrigated 
area absorbed moisture sufficient to allow of keeping up a normal 
irrigation without much overflow. The temperature of the 
water in the tubs was, of course, a little higher than in the 
channels from which paddy fields are commonly supplied, but 
the difference between the water in the frames and that on 
adjoining ordinary rice fields amounted, according to several 
observations during July and August, in maximo only to about 
TC. Our contrivance had, however, this disadvantage that the 
plants of the small patches not being surrounded by other 
plants were in a somewhat better condition as to the supply of 
solar light than rice on large areas. The whole experimental 
field had been ploughed and converted into a swamp in the 
preceding March, all lumps being crushed, the soil well mixed 
and levelled, whereupon the frames were sunk in. 
As the purpose of the experiment was to determine how much 
assimilable nitrogen, phosphoric acid, potash, and lime are 
requisite for the production of a maximum rice crop, all 
fertilizers were given in the most soluble form, viz the nitrogen 
as ammonium sulphate, the phosphoric acid as ordinary sodium 
phosphate, the potash as carbonate and the lime in the slaked 
condition. Besides this, one special series was established 
with regard to the effect of green manure as a nitrogenous 
fertilizer. In several districts of Japan the farmers sow in 
September or October between the rice a leguminous plant 
called “genge ” (Astragalus lotoides) which attains in the next 
year the flowering stage before the rice is transplanted. At that 
time the whole genge crop is incorporated in the field on which 
