Soil Carbon Storage is Not Always Influenced by Tillage PracticesFebruary 26, 2009The practice of no-till has increased considerably during the past 20 yr. Soils under no-till usually host a more abundant and diverse biota and are less prone to erosion, water loss, and structural breakdown than tilled soils. Their organic matter content is also often increased and consequently, no-till is proposed as a measure to mitigate the increase in atmospheric carbon dioxide concentration. However, recent studies show that the effect of no-till on carbon sequestration can be variable depending on soil and climatic conditions, and nutrient management practices. Researchers at Agriculture and Agri-Food Canada (Québec City) investigated the impacts of tillage (no-till vs. moldboard plowing) and N and P fertilization on carbon storage in a clay loam soil under cool and humid conditions in eastern Canada. Corn and soybean had been grown in a yearly rotation for 14 yr. The results of the study were reported in the 2009 January-February issue of the Soil Science Society of America Journal. The authors concluded that their investigation indicates "-no-till enhanced soil organic carbon (SOC) content in the soil surface layer, but moldboard plowing resulted in greater SOC content near the bottom of the plow layer. When the entire soil profile (0-60 cm) was considered, both effects compensated each other which resulted in statistically equivalent SOC stocks for both tillage practices". The effects of tillage and N fertilization varied depending on the soil depth considered. When considering only the top 20 cm of soil, the lowest C stocks were measured in the plowed soil with the highest N fertilizer level, whereas the highest SOC stocks were observed in the NT treatment with the highest N rate. The authors hypothesized that while N fertilization favored a greater residue accumulation in the top 20 cm of no-till soils, mixing of crop residue with soil particles and N fertilizer by tillage stimulated the mineralization of residue and native soil carbon. However, when accounting for the whole soil profile, these variations in the surface 20 cm of soil were counterbalanced by significant SOC accumulation in the 20- to 30-cm soil layer of tilled soils, resulting in statistically equivalent SOC stocks for all tillage and N treatments. This study further emphasizes the importance of taking into account the whole soil profile when determining management effects on SOC storage, especially when full-inversion tillage is involved. The authors conclude that "only considering the top 20 cm of soil would have led us to an erroneous evaluation of the interactive effects of tillage and N fertilization on SOC stock". Field studies of the impact of tillage and fertilization on carbon storage have yielded contrasting results in various parts of the world. An explanation of the high intersite variability of the influence of no-till on soil carbon storage will require that we understand the impacts of no-till and fertilizer management on SOC sequestration for various soil and climatic conditions. Further, researchers at Agriculture and Agri-Food Canada are pursuing their investigations to understand the factors that control the accumulation of soil carbon at depth under moldboard plowing. Specifically, they now focus their efforts on the role of clay particles and soil aggregation in stabilizing carbon. The Soil Science Society of America (SSSA) |
|||||||||||||||||||||
| Related Tillage Current Events and Tillage News Articles Study shows more corn for biofuels would hurt water More of the fertilizers and pesticides used to grow corn would find their way into nearby water sources if ethanol demands lead to planting more acres in corn, according to a Purdue University study. Alternative agricultural practices combine productivity and soil health The progressive degradation of useful soils for agriculture and farm animal husbandry is a growing environmental and social problem, given that it endangers the food safety of an increasing world population. Purdue-developed tool can get most pollution control for the money There may be thousands of things large and small that can be done to better control pollution on even the smallest waterways, and a new tool developed at Purdue University may help sort out how to choose the best ones. Crop Models Help Increase Yield per Unit of Water Used Crop water use efficiency (WUE, or yield per unit of water used), also known as crop water productivity, can be improved through irrigation management and methods, including deficit irrigation (irrigating less than is required for maximum yields) and supplemental irrigation (irrigating to supplement precipitation so as to avoid crop failure or severe yield decline). Researchers to determine if aeration reduces compaction, runoff on no-till fields Much of Texas' wheat may be grazed as a part of a dual-use crop. But many fields are still prepared using conventional tillage, which may not efficiently capture rainfall - a key to economic success in a semi-arid environment, said a Texas AgriLife Research scientist. AgriLife Research drip irrigation project yields promising results Subsurface drip irrigation was able to produce up to four bales of cotton per acre with less water than conventional irrigation methods at the Texas AgriLife Research station near Chillicothe. Long-term study of orchard ground cover management systems Orchard floor and groundcover management is important to fruit growers, affecting the efficiency of orchard operations, fruit tree performance, and soil quality. Will Large Amounts of Soil Carbon be Released to the Atmosphere if Grasslands are Converted to Energy Crops? Grasslands in the Conservation Reserve Program (CRP) in the United States may be increasingly converted to growing bioenergy grain crops. Biofuel carbon footprint not as big as feared, Michigan State University research says Publications ranging from the journal Science to Time magazine have blasted biofuels for significantly contributing to greenhouse gas emissions, calling into question the environmental benefits of making fuel from plant material. But a new analysis by Michigan State University scientists says these dire predictions are based on a set of assumptions that may not be correct. Preventing Soil Erosion in Continuous Corn With recent increase in the cost of energy and subsequent explorations into alternative energy sources, the increased harvest of corn residue for cellulosic ethanol production is likely in the future. More Tillage Current Events and Tillage News Articles |
|||||||||||||||||||||
|
|||||||||||||||||||||
|
|||||||||||||||||||||