Tillage and Urea Fertilizer Application Impacts on Soil C Fractions and Sequestration

Abstract

Conservation tillage has been considered a smart agriculture practice which preserves soil organic carbon (SOC). However, little work on the labile C fractions in South Africa has been documented. As such, this work focused on C fractions under different management systems. The objective of this study was to assess the impact of different tillage techniques and fertilizer application rates on soil C fractions along the soil profile. Samples from no-till (NT), conventional tillage after 5th season (CT-Y5), and annual conventional tillage, longer than 5 years (CT-ANNUAL) at 0, 60, 120, and 240 kg N ha−1 were taken at 0–10, 10–20, and 20–30 cm depths and analyzed for C fractions. The 30 cm depth was chosen as the sampling depth because of the 30 cm plough layer. At 0–10 cm, soil NT had higher total C, organic C, particulate organic C (POC), and permanganate oxidizable C (POxC) for all application rates, especially in the control treatment, compared to both the CT-Y5 and CT-ANNUAL treatments (p −1 (p −1 application rate in dryland agriculture is recommended.

Keywords

• conservation tillage
• particulate organic C
• microbial biomass C
• permanganate oxidizable C
• urea fertilizer