The crops of the country may be roughly divided into rainfall, irrigated, and swamp kinds. The first are sown at the commencement of the wet season, and are greatly affected by the distribution of the rain, but include the most important sources of food. These are Guinea corn, millet, maize, groundnuts, cassava, sweet potatoes, etc. An inadequate or irregular rainy season often causes famine conditions. The irrigated crops are yams, Colocasia, onions, tobacco, peppers, rama-fibre, and wheat, the last being almost confined to the country north of the 11th degree. Cassava and sugar-cane are also frequently irrigated in the drier districts to the north. Irrigation is performed in the northern localities by means of the shaduf. The swamp crops are rice, Colocasia, and sugar-cane. The first is grown upon a flat-dug surface, the second upon high ridges made of swamp mud, and the third on low ridges bordering the rice fields. The villages north of Kano are often entirely built of the stalks of Guinea corn, and Fig. 31 represents a principal hut within such a structure. The fencing of the fields in this locality is generally made of the same material, but in the vicinity of Kano itself, Euphorbia or thorn hedges are more common. Near Rogo, fences and hedges are usually dispensed with, paths forming the boundaries between fields. The following table of value of exports shows the progress in the last five years before amalgamation with the Southern Provinces. The subsequent years are given at the end of this chapter. VALUES OF EXPORTS 1908 1909 1910 1911 1912 £ £ £ £ £ Rubber 33,050 40,000 37,900 53,511 [8] Shea nut products 70,900 93,050 43,150 40,496 51,409 Palm kernels 47,150 41,750 66,100 52,637 64,432 Groundnuts 13,650 16,350 8,150 10,377 18,930 Gum[9] 8,850 6,650 9,750 5,436 1,785 Cotton 1,300 4,400 1,850 945 [8] Benniseed 2,000 4,000 2,300 2,582 2,972 Fibre 1,382 4,061 — — — Livestock 2,600 1,300 3,750 6,357 9,132 Gutta percha (“Balata”) — — 2,262 6,695 4,267 Skins and hides[10] — — 5,214 37,809 68,832 Ostrich feathers — — 2,615 7,225 12,621 =RUBBER.=—The extent of the export of this commodity from the Northern Provinces was less generally recognised than that from the coast countries, for the reason that the Northern Nigeria’s exports are necessarily shipped from Southern Nigerian ports, and have been included in the statistical figures of that country.