Mountainous islands, born of volcanic forces or the partial submergence of coastal ranges, have steep surfaces and scant lowlands. Their inhabitants command limited area at best. Driven to agriculture by their isolation, drawn to it by the favorable oceanic climate, such islands develop terrace tillage in its most pronounced form. On the precipitous pitch of Teneriffe, every particle of alluvial soil is collected to make gardens. Long lines of camels, laden with boxes of earth, may be seen coming almost daily into the town of Santa Cruz, bringing soil for the terraces.[1281] This is desperate agriculture. Irrigated terraces scar the steep slopes of many Polynesian islands.[1282] They are highly developed among the Malay Battaks of Sumatra, especially for rice culture.[1283] In Java, Bali and Lombok they reach a perfection hardly equalled elsewhere in the world. In Java they begin at an altitude of 1000 feet, cutting main and branch valleys into amphitheaters, and covering hundreds of square miles.[1284] On the volcanic slopes of Lombok the terrace plots vary from many acres to a few square yards, according to the grade, while a complete system of irrigation uses every brook to water the terraces. Here as in Java the work began at a very early period, when it was probably introduced among the native Malays by Brahmans from India.[1285] Japan, two-thirds of whose area is mountainous, has terraced its steep valley walls often up to 2000 feet or more, and utilized every patch of ground susceptible of tillage.[1286]
Among mountain savages.
A mountain environment often occasions a forced development in the form of agriculture among peoples who otherwise still linger in a low stage of barbarism or savagery. The wild, head-hunting Igorots, inhabiting the Cordilleras of north central Luzon, have levelled the face of their mountains into a series of platforms, held by retaining walls from twenty to thirty feet high. On these they cultivate upland rice at an altitude of 5000 feet. The Igorot province of Bontoc contains valleys in which every available foot of land is terraced for rice, and which present artificial landscapes vividly recalling Japan. Labor is the heritage of each inhabitant. Every man, woman and child down to ten years of age shares in the work of providing food.[1287] Africa shows parallel cases. The Angoss people, a savage negro tribe who occupy part of the Murchison Range in northern Nigeria, have mapped out all their sloping land into little terraces, sometimes only a foot or two wide. One of their peaks, 4135 feet high, has its plateau top covered with populous villages, owing to the protection of the site, and every inch of its slope cut into terraces planted with millet and guinea corn.[1288] A more primitive form of this tillage is found in the country of the Marunga negroes, who occupy the steep western face of the rift valley filled by Lake Tanganyika. Here Cameron found the surface not regularly terraced, but retaining walls of loose stones disposed at intervals, which served to hold the soil in place, without greatly altering the natural slope. The scene recalled the terraced heights of Switzerland, and the people working there looked like flies on a wall.[1289] In the semi-arid country of Sudanese Darfur, where only the mountain districts are well watered and thickly populated, small terraces for grain and melons cover all the slopes.[1290]
Fertilizing
Mountain agriculture is necessarily laborious. The paucity of arable land precludes the possibility of letting fields lie fallow. These, to prevent exhaustion, must be constantly and abundantly fertilized, all the more as conditions of excessive subærial denudation found in the steep slope and usual heavy rainfall of mountains, as well as possible glacial scouring of the land in the past, have greatly attenuated the layer of soil called upon to support plant life. The Swiss or Tyrolese farmer cherishes his manure pile as at once source and badge of his wealth. After harvest it is carted or carried in baskets not only to the terraces, but also to the wide alluvial fan that grows his oats and rye, to his meadows and hay fields. Both in Mexico and Peru the soil received a dressing of poudrette. Manuring was most extensive where population was densest, as in the isolated mountain valleys opening out upon the desert coast of Peru. Every kind of organic refuse was utilized, and fish was buried with the kernels of maize as a fertilizer. The deposits of guano found on the headlands and off-shore islands were used from the remotest times. Different guano beds were assigned to the several provinces, and the breeding places of the birds were protected by law.[1291] Ashes and decayed wood were employed for the same purpose, or plants were dug into the soil, while human manure was in Mexico a marketable commodity as in China.[1292]
Economy of level land for houses and villages.
In all mountain regions where population has begun to press upon the meager limits of subsistence, level land and soil are at a premium. In ancient Peru space was begrudged for the dead.[1293] Cities covered considerable space on the roomy intermontane plateaus; but in the narrow lateral valleys, houses and temples were built on rocks, in order to reserve every fertile spot for agriculture.[1294] The traveler notices the same thing throughout the Alps. Compact villages cling to the mountain sides, leaving the alluvial hem of the stream or level glacial terrace free for the much needed fields. Only in broad longitudinal valleys, like that of Andermatt, do the settlements complacently spread out their skirts, or on wide alluvial fans where transverse valleys debouch upon the plains. The mountaineers of the Crimea construct their houses against the precipices, excavating into their face and building up the front, with stones, and thus reserve the gentler slopes for vineyards and gardens.[1295] In the Kangra, Kumaon, and Garhwal districts of the British Himalayas, the large Indian villages of the plains give place to small hamlets or detached homesteads, scattered here and there wherever occasional patches of soil on a hillside or in a narrow valley offer hope of sustenance. These hamlets or dwellings are located on the sides of the mountains, because level spots which can be irrigated must be reserved for rice fields.[1296] The high site is also freer from malaria.