Fertilizer management and soil type influence grain zinc and iron concentration under contrasting smallholder cropping systems in Zimbabwe

Manzeke, Muneta G.; Mtambanengwe, Florence; Watts, Michael J.; Hamilton, Elliott M.; Lark, R. Murray; Broadley, Martin R.; Mapfumo, Paul

Abstract

Micronutrient defciencies remain prevalent in food systems of southern Africa, although advances in biofortifcation through crop breeding and agronomy provide opportunities to address these. We determined baseline soil availability of zinc (Zn) and iron (Fe) and the effects of soil type and farmer management on extractable soil Zn and Fe and subsequent concentration in cereal and legume grains under two contrasting agro-ecologies in Zimbabwe. Soil and crop surveys were conducted in Hwedza and Mutasa Districts of Zimbabwe in 2015–16 on 350 locations over diferent soil types. Fields with different levels of productivity (designated as “most” and “least” productive felds) were sampled using an inherited hierarchical randomized sampling design. Grain Zn and Fe concentration in maize (Zea mays), sorghum (Sorghum bicolor), finger millet (Eleusine coracana) and cowpea (Vigna unguiculata) were generally insufcient for adequate human nutrition. A Linear Mixed Efects (LME) model revealed that diethylene triamine penta-acetic acid- (DTPA) extractable soil Zn concentration and grain Zn concentration were affected primarily by feld productivity level. DTPA-extractable soil Zn concentration was more than two-fold greater on the most productive felds (mean 0.8mg kg−1) than on the least productive fields, with mean grain Zn concentration of 25.2mg grain Zn kg−1 which was 13% greater than seen on the least productive felds. An interaction efect of feld productivity level and total soil Zn concentration on DTPA-extractable soil Zn concentration suggests potential contribution of organic matter management to unlocking unavailable forms of soil Zn. DTPA-extractable soil Fe and grain Fe concentration were primarily afected by soil type and crop type, respectively. The LME modelling approach revealed additional soil geochemical covariates afected DTPA-extractable soil Zn and Fe concentration and grain Zn and Fe concentration within Districts. Future studies can therefore be powered to detect their roles at wider spatial scales for sustainable management of crop Zn and Fe
nutrition.

Citation

Manzeke, M. G., Mtambanengwe, F., Watts, M. J., Hamilton, E. M., Lark, R. M., Broadley, M. R., & Mapfumo, P. (2019). Fertilizer management and soil type influence grain zinc and iron concentration under contrasting smallholder cropping systems in Zimbabwe. Scientific Reports, 9, 1-13. https://doi.org/10.1038/s41598-019-42828-0

• Journal Article Type: Article
• Acceptance Date: Mar 25, 2019
• Online Publication Date: Apr 23, 2019
• Publication Date: Apr 23, 2019
• Deposit Date: Apr 30, 2019
• Publicly Available Date: Apr 30, 2019
• Journal: Scientific Reports
• Electronic ISSN: 2045-2322
• Publisher: Nature Publishing Group
• Peer Reviewed: Peer Reviewed
• Volume: 9
• Article Number: 6445
• Pages: 1-13
• DOI: https://doi.org/10.1038/s41598-019-42828-0
• Public URL: https://nottingham-repository.worktribe.com/output/1876625
• Publisher URL: https://www.nature.com/articles/s41598-019-42828-0