Soil Organic Carbon Concentrations and Stocks under Maize/Legume Cropping System in Alfisols of a Savanna Zone, Nigeria

Abstract

Carbon sequestration in soil aggregates and Carbon stock (SOC) under Maize-Legume Cropping system in a Northern Guinea Savanna Alfisol, Nigeria trial was conducted in 2014 and 2015 cropping seasons. The experiment was a randomized complete block design (RCBD), replicated three times and treatments used were: Sole Maize (M), Desmodium (D) and Soybeans (S); Maize-soybeans intercrop (MS), Maize-Desmodiumintercrop (MD), Maize Strip cropped with Soybean (MS 2:4) and Maize Strip cropped with Desmodium (MD 2:4). Data obtained were evaluated for Organic carbon, carbon stock, Bulk density and mean weight diameter of aggregates in the soil. Results obtained show that Mono-crop (Sole) Maize treatment gave significantly higher BD than other treatments at 8WAP and 16WAP, suggesting that soils under sole maize were degraded for sustainable crop production. Organic carbon sequestered over 2014 to 2015 was least under MD and highest under MD2:4 treatments and mean carbon stock sequestered in the macro and micro aggregates was highest under MD 2:4 (28.35 t Cha-1) and least under MD (8.82 t Cha-1). Soil organic carbon (SOC) sequestered in macro aggregates under MS (1.38 gkg-1) were significantly higher than the other treatments. Maize/Desmodium 2:4 treatment was inferred to have best improved soil conditions (quality/health) for sustainable crop production, mitigate climate change and global warming by sequestering carbon better than the other treatments.