Assessment of environmental degradation in Nakambala Mazabuka Zambia
Sokoine University of Agriculture
An environmental degradation assessment was carried out in Nakambala Estate, Mazabuka Zambia in October 1994 to June 1995 . The objectives of the study were: impact change, of the natural sugar plantation vegetation between 1970 and 1993 ; (b) and (a) on demographic resource degradation expansion land to assess the to assess the soil physical and chemical status in cultivated and abandoned areas; and (c) to compare current soil physical and chemical status of the study area with the status when the sugar plantation was being established. Sequential aerial photography was used in assessing sugar plantation expansion and its impact on natural vegetation and land resource degradation. The impact of the sugar plantation expansion on demographic changes and energy needs (fuelwood) was also assessed. A field soil survey was carried out to assess soil condition in terms of general fertility and selected land qualities and characteristics matched with the requirements of irrigated sugarcane using the FAO (1983) land suitability framework. Soil carried out by using indices. degradation assessment wasiii The results of the study were; the sugar plantation expanded by 7 035 ha between 1970 and 1991; human population increased by 4 929 (at 4% per annum) and projected to reach 22 127 by the year 2 000. to sugar Natural vegetation was reduced by 25 % due plantation expansion aggravating the fuelwood deficit situation (5 447 m3/year in 1970 and 4 906 m3/year in 1991) . There was no visible evidence of soil erosion although waterlogging was the prevalent form of land degradation in all the mapping units. The soils are generally eutric (base saturation > 50%) with slight acidic to neutral reaction in cultivated fields (in mapping units; 2W, 10, 11 and 12) to slightly alkaline reaction in areas with abandoned fields (soil mapping unit 13). High soil bulk densities occur in soil mapping unit 2W due to compaction by heavy machinery and due to inherent nature of the soils in mapping units 10, 11, 12 and 13 (heavy clays). Oxygen inavailability (due to poor drainage), physical degradation and poor rooting conditions (due to shallow effective soil depth) are the most limiting conditions for sugarcane changes in chemical status growing. Over time, noticeable (sodication) was low in all the mapping units except in unit 10 where sodication development was noticed. Adverse soil physical changes (crusting and surface sealing) occurred in soil mapping units 11, 13. 12 andiv To stem environmental deforestation, degradation in the form of energy utilization from fuelwood should be reduced by electrifying township housing units. The continued use of vetiva grass for drain protection is advised. Alternative land uses in soil mapping units 11, 12 and 13 and complete abandonment of monocropping practices in these soils is strongly recommended.
MSc. Dissertation in Agricultural Engineering
Sugar plantation expansion, Land resource degradation, Environmental degradation, Mazabuka-Zambia