Reapplication of biochar, sewage waste water, and NPK fertilizers affects soil fertility, aggregate stability, and carbon and nitrogen in dry-stable aggregates of semi-arid soil

Chinyere Blessing Okebalama; Bernd Marschner

doi:10.1016/j.scitotenv.2022.161203

Reapplication of biochar, sewage waste water, and NPK fertilizers affects soil fertility, aggregate stability, and carbon and nitrogen in dry-stable aggregates of semi-arid soil

Sci Total Environ. 2023 Mar 25:866:161203. doi: 10.1016/j.scitotenv.2022.161203. Epub 2022 Dec 26.

Authors

Chinyere Blessing Okebalama¹, Bernd Marschner²

Affiliations

¹ Department of Soil Science, Faculty of Agriculture, University of Nigeria Nsukka, Nigeria; Department of Soil Science/Soil Ecology, Ruhr-Universität Bochum, Universitätsstr, 150, D-44780 Bochum, Germany. Electronic address: chinyere.okebalama@unn.edu.ng.
² Department of Soil Science/Soil Ecology, Ruhr-Universität Bochum, Universitätsstr, 150, D-44780 Bochum, Germany.

PMID: 36581285
DOI: 10.1016/j.scitotenv.2022.161203

Abstract

Biochar has been applied to increased soil nutrients, especially C. In RCBD, control fresh water (CFW), sewage wastewater (SWW), NPK fertilizer, rice husk biochar (RHB), and NPK + RHB treatments were arranged with four replications. Soil chemical properties, dry-stable aggregate fractions [4.75-2.00 (Lma), 1.00-2.00 (Mma), 0.25-1.00 (Sma), and < 0.25 mm (Mia)], and aggregate total carbon (TC) and total nitrogen (TN) concentrations were evaluated over a 4-year period with repeated treatment additions in a vegetable-based rotation system. Soils amended with RHB, NPK and NPK + RHB showed slight acidification but no significant change in exchangeable cation content. The concentration of TC increased with NPK + RHB, NPK and RHB, while TN and available P increased with NPK and NPK + RHB treatments. The SWW increased soil pH and Na⁺ but decreased K⁺ concentration. Reapplication of SWW and NPK + RHB resulted in an increase in Lma formation by 28 % and 29 %, and MWD by 19 % and 21 %, respectively. The NPK and NPK + RHB treatments increased TC and TN in all aggregate fractions, while RHB only increased TC in macro-aggregates (4.75-0.25 mm) and TN in Sma. The increase in aggregate TC concentration was approximately 1.50-2.00 folds greater with NPK + RHB than with NPK and RHB treatments. Although the TC concentration was highest in both Mma and Sma fractions with the NPK + RHB treatment, the greater association of Lma (44 %) and Mma (31 %) with soil TC content may significantly affect the soil sustainability. The TC in Mma fraction was reflected in MWD (r = 0.53*, P = 0.05). Reapplication of RHB had limited potential for C and N sequestration in soil aggregates, but its combination with NPK produced a superior response in soil nutrients retention, soil structural stability, and TC and TN sequestration potential in micro- and macro- aggregate fractions. Therefore, NPK + RHB treatment is best suited for the sustainable management of the study and similar soils.

Keywords: Aggregate C; Aggregate N; Inorganic fertilizer; Mean weight diameter; Rice husk biochar.