Treated sewage effluent (water) potential to be used for horticultural production in Botswana.

Abstract

Botswana being semi-arid and arid country, the provision of drinking water and water for agricultural production is becoming increasingly scarce and expensive. Measures that can augment the available sources of water or measures that can reduce the demand on potable water should be given serious consideration. Horticulturists have incorporated new technology into many of their production programs, which has enabled them to grow more horticultural crops with less water; however, more effort is needed. Techniques such as drip irrigation, sensors, growing plants with low water requirements, timing and scheduling of irrigation to the growth needs of the plant, mulching, and establishing a minimum water quality standard for horticultural crops must be used to stretch agricultural water supplies. Recycling agricultural water and using treated municipal sewage effluent is a viable option for increasing horticultures’ future water supply in Botswana. Agriculture wastewater and sewage effluents often contain significant quantities of heavy metals and other substances that may be toxic to people but beneficial to horticultural crops. However, before sewage effluent can be used for commercial production of vegetables and fruits, research must be undertaken to determine whether there is accumulation of heavy metals and faecal coliforms in the edible portion of the horticultural produce which may be detrimental to human health 15–20 years later. Research must be undertaken to assess the impact of sewage effluent on soil physical, chemical properties and environment after continued use.