In addition to the forest lands, which have long been made to contribute plant food to the cultivated fields through fuel ashes, there are large areas which contribute green manure and compost material. These are chiefly hill lands, aggregating some twenty per cent of the cultivated fields, which bear mostly herbaceous growth. Some 2,552,741 acres of these lands may be cut over three times each season, yielding, in 1903, an average of 7980 pounds per acre. The first cutting of this hill herbage is mainly used on the rice fields as green manure, it being tramped into the mud between the rows after the manner seen in Fig. 114.
This man had been with basket and sickle to gather green herbage wherever he could and had brought it to his rice paddy. The day in July was extremely sultry. We came upon him wading in the water half way to his knees, carefully laying the herbage he had gathered between alternate rows of his rice, one handful in a place, with tips overlapping. This done he took the attitude seen in the illustration and, gathering the materials into a compact bunch, pressed it beneath the surface with his foot. The two hands smoothed the soft mud over the grass and righted the disturbed spears of rice in the two adjacent hills. Thus, foot following foot, one bare length ahead, the succeeding bunches of herbage were submerged until the last had been reached, following between alternate rows only a foot apart, there being a hill every nine to ten inches in the row and the hands grasping and being drawn over every one in the paddy.
He was renting the land, paying therefor forty kan of rice per tan, and his usual yield was eighty kan. This is forty-four bushels of sixty pounds per acre. In unfavorable seasons his yield might be less but still his rent would be forty kan per tan unless it was clear that he had done all that could reasonably be expected of him in securing the crop. It is difficult for Americans to understand how it is possible for the will of man, even when spurred by the love of home and family, to hold flesh to tasks like these.
The second and third cuttings of herbage from the genya lands in Japan are used for the preparation of compost applied on the dry-land fields in the fall or in the spring of the following season. Some of these lands are pastured, but approximately 10,185,500 tons of green herbage grown and gathered from the hills contributes much of its organic matter and all of its ash to enrich the cultivated fields. Such wild growth areas in Japan are the commons of the near by villages, to which the people are freely admitted for the purpose of cutting the herbage. A fixed time may be set for cutting and a limit placed upon the amount which may be carried away, which is done in the manner seen in Fig. 115. It is well recognized by the people that this constant cutting and removal of growth from the hill lands, with no return, depletes the soils and reduces the amount of green herbage they are able to secure.
Through the kindness of Dr. Daikuhara of the Imperial Agricultural Experiment Station at Tokyo we are able to give the average composition of the green leaves and young stems of five of the most common wild species of plants cut for green manure in June. In each 1000 pounds the amount of water is 562.18 pounds; of organic matter, 382.68 pounds; of ash, 55.14 pounds; nitrogen, 4.78 pounds; potassium, 2.407 pounds, and phosphorus, .34 pound. On the basis of this composition and an aggregate yield of 10,185,500 tons, there would be annually applied to the cultivated fields 3463 tons of phosphorus and 24,516 tons of potassium derived from the genya lands.
In addition to this the run-off from both the mountain and the genya lands is largely used upon the rice fields, more than sixteen inches of water being applied annually to them in some prefectures. If such waters have the composition of river waters in North America, twelve inches of water applied to the rice fields of the three main islands would contribute no less than 1200 tons of phosphorus and 19,000 tons of potassium annually.
Dr. Kawaguchi, of the National Department of Agriculture and Commerce, informed us that in 1908 Japanese farmers prepared and applied to their fields 22,812,787 tons of compost manufactured from the wastes of cattle, horses, swine and poultry, combined with herbage, straw and other similar wastes and with soil, sod or mud from ditches and canals. The amount of this compost is sufficient to apply 1.78 tons per acre of cultivated land of the southern three main islands.
From data obtained at the Nara Experiment Station, the composition of compost as there prepared shows it to contain, in each 2000 pounds, 550 pounds of organic matter; 15.6 pounds of nitrogen; 8.3 pounds of potassium, and 5.24 pounds of phosphorus. On this basis 22,800,000 tons of compost will carry 59,700 tons of phosphorus and 94,600 tons of potassium. The construction of compost houses is illustrated in Fig. 116, reproduced from a large circular sent to farmers from the Nara Experiment Station, and an exterior of one at the Nara Station is given in Fig. 117.
This compost house is designed to serve two and a half acres. Its floor is twelve by eighteen feet, rendered watertight by a mixture of clay, lime and sand. The walls are of earth, one foot thick, and the roof is thatched with straw. Its capacity is sixteen to twenty tons, having a cash value of 60 yen, or $30. In preparing the stack, materials are brought daily and, spread over one side of the compost floor until the pile has attained a height of five feet. After one foot in depth has been laid and firmed, 1.2 inches of soil or mud is spread over the surface and the process repeated until full height has been attained. Water is added sufficient to keep the whole saturated and to maintain the temperature below that of the body. After the compost stacks have been completed they are permitted to stand five weeks in summer, seven weeks in winter, when they are forked over and transferred to the opposite side of the house.
If we state in round numbers the total nitrogen, phosphorus and potassium thus far enumerated which Japanese farmers apply or return annually to their twenty or twenty-one thousand square miles of cultivated fields, the case stands 385,214 tons of nitrogen, 91,656 tons of phosphorus and 255,778 tons of potassium. These values are only approximations and do not include the large volume and variety of fertilizers prepared from fish, which have long been used. Neither do they include the very large amount of nitrogen derived directly from the atmosphere through their long, extensive and persistent cultivation of soy beans and other legumes. Indeed, from 1903 to 1906 the average area of paddy field upon which was grown a second crop of green manure in the form of some legume was 6.8 per cent of the total area of such fields aggregating 11,000 square miles. In 1906 over 18 per cent of the upland fields also produced some leguminous crop, these fields aggregating between 9,000 and 10,000 square miles.