Tropentag, September 20 - 22, 2017 in Bonn "Future Agriculture: Social-ecological transitions and bio-cultural shifts"

Corn Cob Biochar Improves Aggregate Characteristics of a Tropical Sandy Loam

¹The Ohio State University, United States of America
²Aarhus University, Dept. of Agroecology, Denmark
³University of Cape Coast, Soil Science, Ghana

Abstract

Most tropical soils are highly weathered and are vulnerable to soil erosion due to their poor aggregate characteristics. This study assessed how corn cob biochar applied at 0 [CTRL], 10 t ha^-1 [BC-10] and 20 t ha^-1, [BC-20] and 20 t ha^-1 with P (P-enriched biochar) [BC-20+P] to a tropical sandy loam affected several aggregate characteristics. Soil aggregate characteristics are critical indicators of soil structural stability, and they have the propensity to influence soil physical behaviour and functioning. In this study, we investigated the effect of corn cob biochar on the aggregate characteristics of a highly weathered tropical sandy loam. Biochar was incorporated at varying rates to study its effects on the stability, strength and friability of aggregates evaluated. Biochar significantly increased soil organic carbon by 35-66% relative to the untreated soil with a surprising trend of increasing water dispersible clay as biochar rate increased. This was attributed to an increase in pH and a substantial reduction in EC following biochar incorporation. Amount of water stable aggregates was significantly improved by 27-53% in biochar treatments compared to control. Incorporation of biochar decreased the tensile strength of the large aggregates (4–8 mm and 8–16 mm), but increased same in the smaller aggregates (1–2 mm). Soil friability and workability were significantly improved in the BC-20 and BC-20+P treatments. In perspective, incorporation of biochar offers the potential to arrest the rate of degradation in highly weathered tropical soils and salvage the decline in their physical quality by minimising the effects of soil erosion.

Keywords: Aggregate stability, friability, tensile strength, water dispersible clay, workability

Contact Address: Emmanuel Amoakwah, The Ohio State University, 1864 Shyville Rd, 45661 Piketon, United States of America, e-mail: amoakwah.2osu.edu