Carbon sequestration in a long-term conventional versus conservation tillage experiment

Wheel traffic can lead to compaction and degradation of soil physical properties. This study, as part of a study of controlled traffic farming, assessed the impact of compaction from wheel traffic on soil that had not been trafficked for 5 years. A tractor of 40 kN rear axle weight was used to apply traffic at varying wheelslip on a clay soil with varying residue cover to simulate effects of traffic typical of grain production operations in the northern Australian grain belt. A rainfall simulator was used to determine infiltration characteristics. Wheel traffic significantly reduced time to ponding, steady infiltration rate, and total infiltration compared with non-wheeled soil, with or without residue cover. Non-wheeled soil had 4—5 times greater steady infiltration rate than wheeled soil, irrespective of residue cover. Wheelslip greater than 10% further reduced steady infiltration rate and total infiltration compared with that measured for self-propulsion wheeling (3% wheelslip) under residue-protected conditions. Where there was no compaction from wheel traffic, residue cover had a greater effect on infiltration capacity, with steady infiltration rate increasing proportionally with residue cover (R 2 = 0.98). Residue cover, however, had much less effect on inf iltration when wheeling was imposed. These results demonstrated that the infiltration rate for the non-wheeled soil under a controlled traffic zero-till system was similar to that of virgin soil. However, when the soil was wheeled by a medium tractor wheel, infiltration rate was reduced to that of long-term cropped soil. These results suggest that wheel traffic, rather than tillage and cropping, might be the major factor governing infiltration. The exclusion of wheel traffic under a controlled traffic farming system, combined with conservation tillage, provides a way to enhance the sustainability of cropping this soil for improved infiltration, increased plant-available water, and reduced runoff-driven soil erosion.

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On the way towards conservation tillage-soil moisture and mineral nitrogen in a long-term field experiment in Germany

Soil and Tillage Research ◽

10.1016/j.still.2011.07.001 ◽

2011 ◽

Vol 115-116 ◽

pp. 80-87 ◽

Cited By ~ 17

Author(s):

Sabine Gruber ◽

Jens Möhring ◽

Wilhelm Claupein

Keyword(s):

Soil Moisture ◽

Field Experiment ◽

Conservation Tillage ◽

Mineral Nitrogen ◽

Term Field ◽

The Way

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The impact of porosity on organic matter cycling in a two-dimensional porous medium

10.5194/egusphere-egu21-9432 ◽

2021 ◽

Author(s):

Hanbang Zou ◽

Pelle Ohlsson ◽

Edith Hammer

Keyword(s):

Porous Medium ◽

Organic Matter ◽

Carbon Sequestration ◽

Soil Carbon ◽

Pore Network ◽

Pore Scale ◽

Decomposition Of Organic Matter ◽

Organic Matter Cycling ◽

The Impact

Carbon sequestration has been a popular research topic in recent years as the rapid elevation of carbon emission has significantly impacted our climate. Apart from carbon capture and storage in e.g. oil reservoirs, soil carbon sequestration offers a long term and safe solution for the environment and human beings. The net soil carbon budget is determined by the balance between terrestrial ecosystem sink and sources of respiration to atmospheric carbon dioxide. Carbon can be long term stored as organic matters in the soil whereas it can be released from the decomposition of organic matter. The complex pore networks in the soil are believed to be able to "protect" microbial-derived organic matter from decomposition. Therefore, it is important to understand how soil structure impacts organic matter cycling at the pore scale. However, there are limited experimental studies on understanding the mechanism of physical stabilization of organic matter. Hence, my project plan is to create a heterogeneous microfluidic porous microenvironment to mimic the complex soil pore network which allows us to investigate the ability of organisms to access spaces starting from an initial ecophysiological precondition to changes of spatial accessibility mediated by interactions with the microbial community.Microfluidics is a powerful tool that enables studies of fundamental physics, rapid measurements and real-time visualisation in a complex spatial microstructure that can be designed and controlled. Many complex processes can now be visualized enabled by the development of microfluidics and photolithography, such as microbial dynamics in pore-scale soil systems and pore network modification mimicking different soil environments &#8211; earlier considered impossible to achieve experimentally. The microfluidic channel used in this project contains a random distribution of cylindrical pillars of different sizes so as to mimic the variations found in real soil. The randomness in the design creates various spatial availability for microbes (preferential flow paths with dead-end or continuous flow) as an invasion of liquids proceeds into the pore with the lowest capillary entry pressure. In order to study the impact of different porosity in isolation of varying heterogeneity of the porous medium, different pore size chips that use the same randomly generated pore network is created. Those chips have the same location of the pillars, but the relative size of each pillar is scaled. The experiments will be carried out using sterile cultures of fluorescent bacteria, fungi and protists, synthetic communities of combinations of these, or a whole soil community inoculum. We will quantify the consumption of organic matter from the different areas via fluorescent substrates, and the bio-/necromass produced. We hypothesise that lower porosity will reduce the net decomposition of organic matter as the narrower pore throat limits the access, and that net decomposition rate at the main preferential path will be higher than inside branches

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Green manure: Alternative to carbon sequestration in a Typic Ustipsamment under semiarid conditions

Spanish Journal of Soil Science ◽

10.3232/sjss.2018.v8.n3.01 ◽

2018 ◽

Vol 8 ◽

Author(s):

Nelson Virgilio Piraneque Gambasica ◽

Sonia Esperanza Aguirre Forero ◽

Adriano Reis Lucheta

Keyword(s):

Carbon Sequestration ◽

Cover Crops ◽

Green Manure ◽

Block Design ◽

Climatic Variability ◽

Plant Cover ◽

Caribbean Region ◽

Full Potential ◽

Semiarid Conditions

Vegetative soil cover mitigates climatic variability and enhances the balance between mineralization and humification processes. Under aerobic conditions, most of the carbon that enters the soil is labile, but a small fraction (1%) is humified and stable, contributing to the soil carbon reserve; therefore, it is important to assess the carbon content captured after green manure cultivation and decomposition. During two consecutive semesters, July to December 2016 and January to June 2017, green manure plots (Zea mays L., Andropogon sorghum subsp. sudanensis and Crotalaria longirostrata) were cultivated individually, in a consortium or amended with palm oil agro-industrial biosolids in a randomized complete block design with 12 treatments. Once decomposed, the different carbon fractions (organic, oxidizable, non-oxidizable, removable and total) were determined. The results showed high total and organic carbon contents under the sorghum treatment, at 30 and 28 Mg ha-1, respectively, followed by those under the fallow + biosolid treatment, at 29.8 Mg ha-1 and 27.5 Mg ha-1, respectively. Despite the short experiment duration and the possible contributions of previous management on recalcitrant carbon soil stocks, these findings suggest the importance of maintaining plant cover and utilizing green manure in the Colombian Caribbean region. Long-term experiments may be conducted to confirm the full potential of cover crops on carbon sequestration under tropical semiarid conditions.

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