Modelling maize grain yield and nitrate leaching from sludge-amended soils across agro-ecological zones : a case study from South Africa

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dc.contributor.author Ogbazghi, Zekarias M.
dc.contributor.author Tesfamariam, Eyob Habte
dc.contributor.author Annandale, J.G. (John George), 1959-
dc.date.accessioned 2020-06-17T14:15:44Z
dc.date.available 2020-06-17T14:15:44Z
dc.date.issued 2019-10
dc.description.abstract When applying municipal sludge according to crop N requirements, the primary aim should be optimizing sludge application rates in order to maximize crop yield and minimize environmental impacts through nitrate leaching. Nitrate leaching and subsequent groundwater contamination is potentially one of the most important factors limiting the long-term viability of sludge application to agricultural soils. This study assessed maize grain yield and potential nitrate leaching from sludge-amended soils, using the SWB-Sci model, based on crop nitrogen requirements and inorganic fertilizer. The following hypotheses were tested using the SWB-Sci model and 20 years of measured weather data for 4 of the 6 South African agro-ecological zones. Under dryland maize cropping, grain yield and nitrate leaching from sludge-amended soils compared to inorganic fertilizer: (1) will remain the same across agro-ecological zones and sites, (2) will not vary across seasons at a specific site, and (3) will not vary across soil textures. Model simulations showed that annual maize grain yield and nitrate leaching varied significantly (P > 0.05) across the four agro-ecological zones, both for sludge-amended and inorganic fertilizer amended soils. The annual maize grain yield and nitrate leaching from sludge-amended soils were 12.6 t∙ha−1 and 32.7 kgNO3 -N∙ha−1 compared to 10.2 t∙ha−1 and 43.2 kgNO3 -N∙ha−1 for inorganic fertilizer in the super-humid zone. Similarly, maize grain yield and nitrate leaching varied significantly across seasons and soil textures for both sludge and inorganic fertilizer amended soils. However, nitrate losses were lower from sludge-amended soils (2.3–8.2%) compared to inorganic fertilizer (11.1–26.7%) across all zones in South Africa. Therefore, sludge applied according to crop N requirements has a lower environmental impact from nitrate leaching than commercial inorganic fertilizer. Further validation of these findings is recommended, using field studies, and monitoring potential P accumulation for soils that received sludge according to crop N requirements. en_ZA
dc.description.department Plant Production and Soil Science en_ZA
dc.description.librarian pm2020 en_ZA
dc.description.sponsorship Water Research Commission of South Africa (WRC) and East Rand Water Care Works (ERWAT). en_ZA
dc.description.uri https://www.ajol.info/index.php/wsa en_ZA
dc.identifier.citation Ogbazghi, Z.M., Tesfamariam, E H. & Annandale, J.G. 2019, 'Modelling maize grain yield and nitrate leaching from sludge-amended soils across agro-ecological zones : a case study from South Africa', Water SA, vol. 45, no. 4, pp. 663-671. en_ZA
dc.identifier.issn 0378-4738 (print)
dc.identifier.issn 1816-7950 (online)
dc.identifier.other 10.17159/wsa/2019.v45.i4.7548
dc.identifier.uri http://hdl.handle.net/2263/75017
dc.language.iso en en_ZA
dc.publisher Water Research Commission en_ZA
dc.rights © 2019. Water Research Commission.Published under a Creative Commons Attribution 4.0 International Licence (CC BY 4.0). en_ZA
dc.subject Sewage sludge en_ZA
dc.subject Inorganic fertilizer en_ZA
dc.subject Nitrate leaching en_ZA
dc.subject Maize yield en_ZA
dc.subject Agro-ecological zones en_ZA
dc.subject SWB-Sci model en_ZA
dc.title Modelling maize grain yield and nitrate leaching from sludge-amended soils across agro-ecological zones : a case study from South Africa en_ZA
dc.type Article en_ZA


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