The effects of Soil Chemical Characteristics on Accumulation of Native Selenium by Zea Mays Grains in Maize Belt in Kenya
S.B.Otieno, TS Jayne, M. Muyanga

Abstract
Background: Selenium which is an-antioxidant is important for human health enters food chain through crops. Both total amount of selenium in soil and its speciation determines the concentration in food crops. In Kenya Zea mays is consumed by 96% of population hence is a cheap and convenient method to provide selenium to large number of population. Soil chemical factors are known to have antagonistic effects on selenium speciation hence the uptake by Zea mays. The objective of this study was to determine the effects of the four soil chemical characteristics (pH, Tcarbon, CEC, Eh) on accumulation of selenium in Zea mays grains in Maize the Belt in Kenya. Research Methods: About 100 Zea mays grain samples together with 100 soil samples were collected from the study site, put in separate labeled Ziplocs and were transported to laboratories at room temperature for analysis. Maize grains were analyzed for selenium while soil samples were analyzed for pH, Cat Ion Exchange Capacity, Total carbon, and Electrical conductivity. Results: The mean selenium in Zea mays grains varied from 1.82 ± 0.76 mg/Kg to2 .11±0.86 mg/Kg.There was no significant difference between selenium levels between different grain batches {χ (Df =76) = 26.04 P= 1.00}. The pH levels varied from 5.43± 0.58 to 5.85± 0.32. No significant correlations between selenium in grains and soil pH (Pearson’s correlations = - 0.143) was observed. There was no signicant correlations between selenium levels in grains and the four (pH, Tcarbon, CEC,Eh) soil chemical characteristics {F (4,91) = 0.721 p = 0.579} was observed. Conclusion: Using the native selenium accumulation in Zea mays grains as proxy-indicator of selenium speciation in the soil, it can be concluded that the soil chemical characteristics in the study site did not significantly affect the speciation of available selenium species and hence accumulation of native selenium.

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