Soil Quality, Carbon Sequestration and Yield of Maize (Zea mays L.) under Maize/Legume Cropping System in Alfisols of a Savanna Zone, Nigeria

Abstract

The role of maize-legume cropping system on soil quality, carbon sequestration and yield of maize in a Northern Guinea Savanna Alfisol, Nigeria was assessed in 2014 and 2015 rain-fed cropping seasons. The experiment was a Randomized Complete Block Design (RCBD), replicated three times and treatments were Sole (Mono crop) Maize (M), Desmodium (D) and Soybeans (S); Maize/soybeans intercrop (MS), Maize/Desmodium intercrop (MD), Maize Strip cropped with Soybean (MS 2:4) and Maize Strip cropped with Desmodium (M:D 2:4). Data obtained were evaluated for Organic carbon, available phosphorus, total nitrogen, soil pH, and CEC, Bulk density, Soil moisture, mean weight diameter and grain yield of Maize. Results show that mean soil acidity (pH water, 6.37; pH CaCl2, 5.78), mean organic carbon (5.23 to 5.69 g·kg-1) and mean total nitrogen improved (0.66 g·kg-1) in 2015 over values in 2014. Mean weight diameter (MWD) increased from 0.59 in 2014 to 1.05 in 2015; indicating a better aggregation across treatments. Treatment M resulted in significantly higher bulk density (Bd) than other treatments at 8 weeks after planting (WAP) and 16WAP, suggesting that soils under mono-crop maize were impaired for sustainable crop production. Soil organic carbon (SOC) sequestered in macro aggregates under MS (1.38 g·kg-1) was significantly higher than the other treatments. Best maize grain yield (GY) was under sole maize (M) and maize strip cropped with Desmodium (MD2:4) (3.13 t·ha-1 and 2.90 t·ha-1 in 2015, respectively). Maize strip cropped with Desmodium and maize/soybean intercrop enhanced better soil chemical and physical properties than sole maize. Soil quality (SQ) under MD2:4 ranked best (SQ1) for sustainable maize grain production and environmental conservation. Therefore, land use strategies that focus protection of soil organic carbon against further depletion and erosion, contribute nitrogen and/or replenishment of depleted carbon stocks through management techniques that involve legume/cereal cropping systems are advocated for sustainable agricultural production in the Nigerian Savanna zone Alfisols.