At the Fukuoka Experiment Station we learned that the usual depth of plowing for the rice fields is three and a half to four and a half inches, but that deeper plowing gives somewhat larger yields.  As an average of five years trials, a depth of seven to eight inches increased the yield from seven to ten per cent over that of the usual depth.  In this prefecture grass from the bordering hill lands is applied to the rice fields at rates ranging from 3300 to 16,520 pounds green weight per acre, and, according to analyses given, these amounts would carry to, the fields from 18 to 90 pounds of nitrogen; 12.4 to 63.2 pounds of potassium, and 2.1 to 10.6 pounds of phosphorus per acre.

Where bean cake is used as a fertilizer the applications may be at the rate of 496 pounds per acre, carrying 33.7 pounds of nitrogen, nearly 5 pounds of phosphorus and 7.4 pounds of potassium.  The earth composts are chiefly applied to the dry land fields and then only after they are well rotted, the fermentation being carried through at least sixty days, during which the material is turned three times for aeration, the work being done at the home.  When used on the rice fields where water is abundant the composts are applied in a less fermented condition.

The best yields of rice in this prefecture are some eighty bushels per acre, and crops of barley may even exceed this, the two crops being grown the same year, the rice following the barley.  In most parts of Japan the grain food of the laboring people is about 70 per cent naked barley mixed with 30 per cent of rice, both cooked and used in the same manner.  The barley has a lower market value and its use permits a larger share of the rice to be sold as a money crop.

The soils are fertilized for each crop every year and the prescription for barley and rice recommended by the Experiment Station, for growers in this prefecture, is indicated by the following table: 

Fertilization for naked barley. 
Pounds per acre. 
Fertilizers.  N P K
Manure compost 6,613 33.0 7.4 33.8
Rape seed cake 330 16.7 2.8 3.5
Night soil 4,630 26.4 2.6 10.2
Superphosphate 132 9.9
----------------------
Sum 11,705 76.1 22.7 47.5

Fertilization for paddy rice.

Manure compost 5,291 26.4 5.9 27.1
Green manure,
  soy beans 3,306 19.2 1.1 19.6
Soy bean cake 397 27.8 1.7 6.4
Superphosphate 198 12.8
                 ----------------------
       Sum 9,192 73.4 21.5 53.1
                ====== ===== ==== =====
Total for year 20,897 149.5 44.2 100.6

Where these recommendations are followed there is an annual application of fertilizer material which aggregates some ten tons per acre, carrying about 150 pounds of nitrogen, 44 pounds of phosphorus and 100 pounds of potassium.  The crop yields which have been associated with these applications on the Station fields are about forty-nine bushels of barley and fifty bushels of rice per acre.