Another question besides irrigation is now occupying the attention of agriculturists. Heretofore, the wonderful fertility of the soil has been perpetuated by allowing fields to lie fallow for a season, whenever their productiveness threatened to decline. This system is giving place to the more scientific method of fertilizing the land by the use of guano and other substances suitable for the purpose, and no country is better provided than Peru with the best fertilizing products of the world. The islands from which this valuable food for the soil is obtained are all within easy sailing distance of the coast, and their supply is sufficient for the needs of the country for an indefinite period. [Illustration: PORT OF PACASMAYO.] [Illustration: THE CHICAMA RIVER, DEPARTMENT OF LA LIBERTAD.] CHAPTER XXII TRUJILLO AND THE CHICAMA VALLEY [Illustration: HUACO DEL SOL, TRUJILLO.] As the valley of the Nile became the seat of Egyptian civilization when all the rest of Africa was in barbarism, so, in the western world, the valleys of the coast region of Peru formed the centre of social and industrial development at a period more remote than is indicated by existing evidences of any other culture on the South American continent. In the primitive history of mankind it is under the most favorable conditions of soil and climate that the greatest social development is to be traced, and in no part of the world had the simple child of nature apparently less to fear from the elements or more to hope from the beneficent earth than in these smiling valleys. There is no doubt that in ancient times the irrigation of this extensive area was more general and its desert tracts were fewer than at present; and the efforts of the Peruvian government, now directed toward a scientific investigation of the subsoil of this region, aim especially to discover, if possible, some means of restoring these sources of moisture, which were once sufficiently abundant for the fertilization of a vast realm inhabited by a population many times in excess of what it is at present.