Management and irrigation of vertisols derived from basalts in Zimbabwe
1998
Hussein, J.
Vertisols (black clay soils) formed from basalts are potentially very productive under irrigated sugar cane, due to their large nutrient and water holding abilities. However, cane yields on vertisols can be very variable and marked decreases in yield can occur with increasing numbers of ratoons. These yield declines are possibly linked to problems such as poor surface structure, incorrect irrigation management with resultant high groundwaters and salinity/sodicity, poor drying, restricted aeration or compaction. On the chemical side, vertisols can provide large amounts of exchangeable calcium, magnesium and potassium whilst levels of available phosphorus and nitrogen can be increased through good fertilizer/organic management. In order to avoid irrigation problemssuch as rising groundwaters and sodicity or salinity, careful management is vital. This should include correct design and layout of irrigation schemes, accurate scheduling based on field determined total available moistures, and maintenance of surface drains. Sodic vertisols can sometimes be reclaimed through improved drainage coupled with gypsum apllications but this may take a long time.
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