l6 MANURING EXPERIMENTS WITH PADDY RICE. 
under practical conditions. By a joint application of phosphoric 
acid and nitrogen (trial No. 4) a still larger crop was produced, 
although no potash was given in this case. 
As the general result, this series of trials conclusively shows 
that of the three essential nutrients phosphoric acid is in our soil 
in the relative minimum; nitrogen comes next, while potash 
seems to exist in it in amounts sufficent for a large produce of 
rice. From the following 3 series we shall learn how much 
of these nutrients may be economically applied. 
II. Series. Nitrogen. 
Manure per tan : 
25 kilogrms. phosphoric 
acid, 20 kilogrms-potash 
and the following quanti¬ 
ties of nitrogen : 
Straw. 
kilo¬ 
grms. 
Chaff. 
kilo¬ 
grms. 
Hulled 
grain, 
Straw. 
ku wam- 
me. 
Chaff. 
ku wam- 
me. 
Hulled grain, 
actually 
har¬ 
vested. 
kilo¬ 
grms. 
correct¬ 
ed 
yield. 
kilo¬ 
grms. 
actually 
har¬ 
vested. 
koku. 
correct¬ 
ed 
yield. 
koku. 
1) No nitrogen.. 
500 
88 
331 
430 
133 
23 
2-33 
3.02 
2) 5 kilogrms. nitro- 
gen. 
723 
I 21 
424 
576 
193 
32 
2.98 
4.05 
3 ) 7-5 » 
804 
138 
474 
672 
214 
37 
3-33 
4.72 
4 ) 10 », 
904 
138 
5°5 
642 
241 
37 
3-55 
4-50 
5 ) I2> 5 ». ». 
893 
I4O 
515 
662 
238 
37 
3.62 
4.65 
6 ) 15 »» »» 
906 
155 
510 
700 
241 
41 
3 - 5 8 
4-92 
7 ) I 7 , 5 ». 
945 
159 
5*3 
747 
252 
42 
3.60 
5.18 
Judging from these results the best economical effect will be 
secured by an application of 7.5 kilogrms. of easily soluble 
nitrogen to each tan of our soil. A still larger quantity of 
this potent nutrient increases, it is true, the grain slightly and 
the straw considerably, but it is not advisable to apply larger 
doses of it, because the luxuriant development of the straw 
renders the crop liable to lodging or to be thrown down by 
the wind, and also because a copious application of this ex¬ 
pensive nutrient will not compensate for the increase of grain 
and straw even if the feeding value of the latter is incidentally 
enhanced. It must, however, not be forgotten that our soil is 
