Land Use limitations and management option for a Savanna Zone Alfisol

A 50 by 50 m rigid grid survey of part of the Institute For Agricultural Research (IAR) farm in Zaria (11° 10’N and 7°35’E) was carried out to characterize the morphological, physical and chemical properties of soils at the site. Quick crosschecks in areas outside the rigid grid but having seemingly varying soil units was also studied in the field. Two soil units (‘Oxyaquic Vertic Paleustalfs / Gleyic Lixisol’ and ‘Aquic Kandiustalfs / Gleyic Lixisols’) were delineated. Soil samples were obtained from identified horizons of each pedon, air dried, sieved through 2.0mm sieve to obtain sub samples less than 2.0mm for laboratory analysis. Results obtained showed soils of the ‘Oxyaquic Vertic Paleustalfs / Gleyic Lixisol’ to have within its subsoil ‘Argillic’ pedogénetic features, mottling and ‘Gleyic’ properties, and no subsoil acidity problems. The subsoil has increasing clay with depth, and temporary stagnation of water. Soil condition in this unit would however be improved for sustainable crop production by liming and /or incorporation of farmyard manure, contour ridging and construction of field drainage ditches to conduct excess field and subsoil stagnated water away from the fields. Soils of the ‘Aquic Kandiustalfs / Gleyic Lixisols’ have ‘Kandic’ subsoil properties, ‘Gleyic’ and mottled subsoil horizons at shallow depths to the surface horizons, and exchange acidity (H++Al3+) values ranging between 0.6 and 1.4 cmolkg -1, suggesting acid soil problem in this unit. Also, extractable Zn values were very high and could adversely affect growth and production of crops. This problem would be corrected by liming, adequate drainage to remove stagnating subsoil and excess field water, and incorporation of farmyard manure to enhance the soils’ nutrient availability/exchange capacity, control soil acidity build up and improve aeration conditions in the plow layer.