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Sand dams are one of the most successful rainwater harvesting methods, adopted in most of arid and semi-arid lands (ASALs) of Kenya to secure domestic water supply and micro-irrigation. Their ability to maintain acceptable water quality, under extreme climatic conditions of recurrent drought and floods, is therefore of paramount public health concern as various pollutants find easily their way into them. This study assessed the suitability of sand-dam water abstracted via scoop holes (SCHs) and shallow wells (SHWs) in Kitui-West, South-Eastern Kenya. Water quality compliance checks were performed using the specifications of Kenya Bureau of Standards (KEBS) for natural potable water and World Health Organization's (WHO) drinking-water quality guidelines wherever applicable. A total of 48 water samples comprising SCHs (N=33) and SHWs (N=15) were collected during the dry period (February 8 and 28, 2018) and the wet season (March 23, April 20 and May 19, 2018) in three sand dams using well-cleaned plastic bottles, transported in cooler boxes to the laboratory for storage and analysis. They were analyzed for pH, temperature, total dissolved solids (TDS), total hardness (TH), biochemical oxygen demand (BOD), trace metals (Cu, Fe, Mn, Zn, and Cr), Escherichia coli (E. coli) and total coliforms (TCs). Results showed that majority of assessed physicochemical parameters and trace metals complied with KEBS limits at the rates of more than 90% except turbidity, Cu and Fe that complied with low overall scores; 44, 56 and 35% respectively. These three parameters behaved differently in both abstraction methods as their mean values (compliance rates) exceeded KEBS limits in SCHs, that is, 297 NTU (18%), 1.7 mg/L (48%) and 2.22 mg/L (9%) and were below limits in SHWs, that is, 3.1 NTU (100%), 0.89 mg/L (73%) and 0.21 mg/L (87%) respectively. E.coli compliance levels were 48% in SCHs and 87% in SHWs with maximum counts as 300 CFU/100 ml, while TCs were detected at high rates of 94 and 47% respectively with maximum counts as 2,500 CFU/100 ml. Therefore, these results demonstrated that water extracted via SCHs is more unsafe than water from SHWs but both provide water that is microbiologically unfit for direct human consumption. Shallow-well water was found to be physicochemically fit and only requires disinfection while scooped water needs first to be purified with homemade water filters and then chlorinated with available disinfection by-products (DBPs) to increase its potability. Continuous monitoring of sand-dam water quality is recommended so that the public awareness should be raised on time when new contaminants emerge or exiting ones become intense so as to avoid possible health risks that can result from unnoticed long-term exposure.

Residual soil N following maize (Zea mays L.) harvest is susceptible to leaching over winter. There is no available information regarding the combination of intercropping system and water table control to conserve soil N in maize production systems. A 2‐yr study was conducted to examine the effects of cropping systems (monocrop maize, and maize intercropped with annual Italian ryegrass [Lolium multiflorum Lam.]) and water table controls (free drainage, or subirrigation to establish water table depths at 70 and 80 cm below the soil surface) on conserving soil N, under climatic and soil conditions of southwestern Québec. The resulting six treatments were fertilized in the spring with 270 kg N ha−1. The effects of adding fertilizer at 0, 180, and 270 kg N ha−1 on monocrop maize with free drainage were also investigated. Soil cores of 1 m in depth were collected in the spring and fall of 1993 and 1994. In 1993, intercropping decreased the amount of NO−3‐N in the top 1 m of the soil profile by 47% (92.3 kg N ha−1) relative to monocropped maize at harvest time. Water table depth had less effect on soil NO−3‐N content than cropping system. Both increasing water table depth and monocrop maize enhanced downward movement of NO−3‐N during the growing season and following spring. More NO−3‐N was present in freely drained subsoil under maize given 270 kg N ha−1 than under maize given 180 kg N ha−1.