Soil Carbon Improvement Under Long-Term (36 Years) No-Till Sorghum Production In A Sub-Tropical Environment

Soil organic matter (SOM) is considered an important indicator of soil quality, which can be impacted by crop production practices such as tillage. In this study, two long-term tillage regimes (conventional tillage [CT] and no tillage [NT], conducted for 36 years) were compared in continuous sorghum production in a sub-tropical environment in southeast Texas. The positive effects of long-term NT practice were more conspicuous at the soil surface compared with the deeper soil profiles. The SOC was greater (1.5 t C ha(-1)greater) in the NT system compared with the CT system. Results from an incubation study indicate that the rate of C-min at 0-5 cm soil depth was significantly greater (164 mu g of CO2-C g(-1)of soil greater) in NT than that of CT, but this trend was reversed at 10-20 cm depth wherein the C-min rates were 106 mu g of CO2-C g(-1)of soil greater in CT compared with NT, which is likely because of soil disturbance during the study. Soil cumulative CO2-C emissions were greater in the CT system (7.28 g m(-2)) than in the NT system (5.19 g m(-2)), which is primarily attributed to high soil temperature conditions in the CT system. Sorghum grain yield however was not influenced by the differences in SOC content in this long-term experiment. Overall, the present study found that long-term conservation tillage improved SOC stock and reduced carbon loss, thus had a positive impact on soil health and sustainability.