Biological activity of soils in Ukraine depending on tillage options: A meta-analysis

Abstract

Tillage is one of the major factors affecting soil biological activity, resulting in changes in soil organic carbon (SOC) content, providing for carbon sequestration and shifts in carbon dioxide emission from soils. Current climate change and aggravation of global warming through the increased emission of carbon dioxide are main driving forces for global transformation of agricultural practices in the direction of climate-smart agriculture (CSA), which requires the implementation of such crop cultivation practices that result in the minimization of SOC losses and carbon dioxide emissions. The magnitude and direction of different tillage practices affecting soil biological activity are different, therefore, the best tillage options should be chosen for implementation in national CSA systems to ensure achieving the global sustainability goals. This nationwide meta-analysis, conducted for tillage practices utilized in Ukrainian agriculture examines scientifically recorded effects of moldboard tillage depth, flat cutter and no-till options on soil respiration rates and cellulose decomposition intensity in dark-chestnut and chernozem soils of Ukraine. This meta-analysis enrolled 45 studies, which met the stipulated scientific quality criteria. Statistical processing was conducted through the standardized mean difference (SMD) model without subgroups at 95% confidence interval (CI). As a result, it was determined that there is subtle impact of moldboard tillage depth on soil biological activity, which is inconclusive and unclear. The similar results were obtained for the comparison between the tillage and no-till groups, where high heterogeneity of the dataset (I2 = 82.8%) resulted in low quality of evidence for the benefits of no-till in SOC sequestration. Besides, zero fail-safe numbers support the suggestion of low-quality evidence in favor of shallow plowing advantage over deep plowing, as well as no-till against tillage. As for the difference between the groups of moldboard and flat cutter tillage, it was established that there is strong enough evidence for the advantage of flat cutter tillage in terms of soil respiration rates and cellulose decomposition intensity reduction. Further studies in this direction are required to fill the gaps in current meta-analysis, especially in terms of no-till options and their effect on biological activity of Ukrainian soils in different cropping systems.