SOIL

Soil is formed by the action of moisture; vegetation; animals and man on the loose products formed by the weathering of rocks. Climatic conditions are involved at every stage of these processes. Hence, there is a broad parallelism between soil types and the main climatic belts. Most of the soils in the Zaria area fall under the leached ferruginous (jangargari/jarkasa) tropical soils. While the soils near the inselbergs may be classified as weakly developed soils the Fadama soils are described as hydromorphic soils which are more fertile for agricultural purposes. A close study of the soils of the area indicates that the lower part of the soil is derived insitu from the underlying weathered gneiss and contains pieces of quartz and mica. While the upper part is a mixture of similar material combined with transported, probably wind blown particles. The process of soils formation is characterized by the accumulation of clay between a depth of 36 and 119cm. Iron deposits are found below the layer of clay, which is indicated by the appearance of red mottles. At the lower level hard iron concretions are found. Higher up the slope, there is an improvement in the drainage conditions and the soils are generally reddish in colour. There is complete absence of mottles at this level, although a few may occur at greater depths. But generally, iron concretions are absent at such levels. The soils gradually become greyer in colour, lower down the slope and there is the occurrence of mottled horizon nearer to the surface. There is increase in the number of iron concretions here, while in some places iron pan can be seen out cropping at lower slope positions. The soils in the fadama areas are mostly dark grey clays with poor drainage. The soils here have been formed mostly with alluvial material. They are therefore rich in nutrients and have a good water supply in excess that persists in the dry season. Because of the fertility of the soil, various crops like rice, sugar cane, cassava, indigo, vegetables and tobacco are grown on the fadama soil all the year round in areas like Kamacha, TukurTukur, Tukurwa, Fadamar Bono and so on. Lateritic iron pan features prominently in many places at the level of about 700m (2,300 ft), which looks hard and vesicular in appearance and it sometimes contain quartz. Deep soils usually occur in areas around the granitic inselbergs. The soils consist mainly of weathered materials and they also contain a lot of un-weathered fragments of quartz and feldspar. Very deep red clay soils are found further away from the inselbergs. The soils are mottled and generally of a grey colour in the lower slopes and in poorly drained areas. Most of the soils contain 30-40 percent of clay at a reasonable depth and this allows for good moisture retention. The soils are inherently rather poor and cannot therefore sustain intensive agriculture for long without the use of fertilizer. To maintain the fertility of the soil, farmers in the area used the method of shifting cultivation and bush fallow in agricultural production, which replaced permanent cultivation. The significance of the soil type can be seen in the predominance of agriculture as the main occupation of the people of Zaria. The plains of Zaria with their comparatively fertile soils and reliable rainfall attracted human settlement for at least 2,000 years.