Short term effects of treated greywater by high rate algal ponds process on vegetable yield and soil properties under Sudano‐Sahelian climate conditions

Abstract

Greywater is a valuable additional water source for agriculture in arid and semi‐arid countries subject to water scarcity. However, the impacts of applying greywater to agricultural land in the Sudano‐Sahelian regions are not adequately understood. This study evaluates the impacts of using greywater, treated by the High Rate Algal Ponds system (HRAPs), on soil characteristics and okra growth and yield in the Sudano‐Sahelian regions. The methodology consisted of growing okra under four different irrigation conditions: (i) treated greywater (TGW); (ii) fresh well water (FWW); (iii) TGW and chemical fertilizer (TGW + FERT) and (iv) FWW and chemical fertilizer (FWW + FERT). The test beds were sampled before and after cultivation to analyze soil pH and sodicity status (e.g., sodium absorption ratio: SAR). The okra growth, fruit yield and total dry biomass were recorded. Fresh fruit weight is significantly higher with TGW (761.17 ± 53.69 kg.ha−1) compared to FWW (497.15 ± 100.02 kg.ha−1) and FWW + FERT (307.93 ± 100.04 kg.ha−1). This result likely occurs due to the nutrients (e.g., nitrogen) present in TGW. Conversely, the average SAR of soil irrigated with TGW + FERT (12.47) and TGW (8.83) are significantly higher than those of the soil irrigated with FWW (2.92) and soil before cultivation (0.95). Therefore, it is recommended that soil salinity or/and sodicity is monitored when irrigating with TGW and that well water is used for every third irrigation cycle to prevent soil degradation though increased salinity. Overall, the appropriate reuse of greywater improves food security and the sustainability of agriculture in arid to semi‐arid regions. © 2017 American Institute of Chemical Engineers Environ Prog, 37: 465–470, 2018