Amending a tropical Arenosol: increasing shares of biochar and clay improve the nutrient sorption capacity Artikel uri icon

Open Access

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Peer Reviewed

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Abstract

  • Tropical Arenosols may be challenging for agricultural use, particularly in semi-arid regions. The aim of this study was to evaluate the impact of the addition of increasing shares of biochar and clay on the nutrient sorption capacity of a tropical Arenosol. In batch equilibrium experiments, the sorption of ammonium-N ( NH 4 + -N ), nitrate-N ( NO 3 - -N ), potassium ( K + ), and phosphate-P ( PO 4 3 - -P ) was quantified for mixtures of an Arenosol with increasing shares of biochar and clay (1%, 2.5%, 5%, 10%, 100%) and the unmixed Arenosol, biochar, and clay. The mid-temperature biochar was produced from Prosopis juliflora feedstock; the clayey material was taken from the sedimentary parent material of a temporarily dry lake. Only the Arenosol–biochar mixture with 10% biochar addition and the biochar increased the NH 4 + -N maximum sorption capacity ( q max ) of the Arenosol, by 34% and 130%, respectively. The q max of PO 4 3 - -P slightly increased with ascending biochar shares (1–10%) by 14%, 30%, 26%, and 42%, whereas the undiluted biochar released PO 4 3 - -P . Biochar addition slightly reduced NO 3 - -N release from the Arenosol but strongly induced K + release. On the other hand, clay addition of 10% and clay itself augmented q max of NH 4 + -N by 30% and 162%; ascending clay rates (1–100%) increased q max for PO 4 3 - -P by 78%, 130%, 180%, 268%, and 712%. Clay rates above 5% improved K + sorption; however, no q max values could be derived. Sorption of NO 3 - -N remained unaffected by clay amendment. Overall, clay addition proved to enhance the nutrient sorption capacity of the Arenosol more effectively than biochar; nonetheless, both materials may be promising amendments to meliorate sandy soils for agricultural use in the semi-arid tropics. Highlights Biochar addition slightly increased NH 4 + -N and PO 4 3− -P sorption, reduced NO 3 − -N release but triggered K + release. Clay addition enhanced sorption of NH 4 + -N, K + , and PO 4 3− -P better than biochar but had no effect on NO 3 − -N. Both substrates can contribute to fertility of Arenosols by increasing their nutrient content and sorption capacity.

Veröffentlichungszeitpunkt

  • Januar 3, 2022