Influence of mouldboard ploughing and shallow tillage on soil physical properties and crop performance

This study was conducted in spring 2011 in a long-term field experiment with the objective of assessing the effect of shallow tillage and mouldboard ploughing on some soil physical properties and crop performance. In this field, different tillage experiments established in 1974. Five treatments were included in the experiment but this investigation considered only two treatments, shallow tillage and mouldboard ploughing. In these two treatments, undisturbed soil samples were taken before sowing the seeds at the depth of 15-20, 25-30 and 35-40 cm for the determination of saturated hydraulic conductivity (Ks), bulk density (Bd), and water retention in laboratory condition. Penetrometer resistance (PR) were measured in the field one month after sowing. Plant density of barley was also counted one month after sowing. Significantly higher Ks value was found for shallow tillage at the depth of 15-20 and 25-30 cm. Bd was significantly lower for mouldboard ploughing for the first two investigating depth and it was higher at 35-40 cm but the difference was not statistically significant. Moreover, Bd was high in both treatments. Significant higher PR value was found for shallow tillage especially at the depth of 5-35 cm but the result was not so high to reduce the root growth. Water content determined parallel with PR measurement was similar for the two treatments. Plant density and crop yield were significantly higher in shallow tilled treatment than in moulboard ploughing. Field water content at 15-20 and 25-30 cm was significantly higher for moulboard ploughing. Water retention at 1 meter suction was also significantly higher in the treatment with mouldboard ploughing. However, the differences of the physical parameters due to tillage treatments was sufficient to markedly influence crop performanc and yield

Carbon sequestration in the subsoil and the time required to stabilize carbon for climate change mitigation

Soils store large quantities of carbon in the subsoil (below 0.2 m depth) that is generally old and believed to be stabilized over centuries to millennia, which suggests that subsoil carbon sequestration (CS) can be used as a strategy for climate change mitigation. In this article, we review the main biophysical processes that contribute to carbon storage in subsoil and the main mathematical models used to represent these processes. Our guiding objective is to review whether a process understanding of soil carbon movement in the vertical profile can help us to assess carbon storage and persistence at timescales relevant for climate change mitigation. Bioturbation, liquid phase transport, belowground carbon inputs, mineral association, and microbial activity are the main processes contributing to the formation of soil carbon profiles, and these processes are represented in models using the diffusion-advection-reaction paradigm. Based on simulation examples and measurements from carbon and radiocarbon profiles across biomes, we found that advective and diffusive transport may only play a secondary role in the formation of soil carbon profiles. The difference between vertical root inputs and decomposition seems to play a primary role in determining the shape of carbon change with depth. Using the transit time of carbon to assess the timescales of carbon storage of new inputs, we show that only small quantities of new carbon inputs travel through the profile and can be stabilized for time horizons longer than 50 years, implying that activities that promote CS in the subsoil must take into consideration the very small quantities that can be stabilized in the long term.We reviewed mathematical models that represent soil carbon dynamics with depth and found thatmost models adopt the diffusion, advection, reaction (decomposition) paradigm. Transport processes play a secondary role in shaping soil carbon profiles, with the difference betweencarbon inputs and decomposition (g) playing a major role. Carbon stocks in the subsoil can be increased by decreasing the rate of change of soil carbon withdepth, increasing vertical transport (v) or decreasing g.imag

On the relationships between the size of agricultural machinery, soil quality and net revenues for farmers and society

Mechanization in agriculture has greatly improved the efficiency of field operations, but also resulted in heavier agricultural vehicles, which has led to increased risks of soil compaction. Hence, farmers benefit from machinery with higher capacity but may suffer from decreased yields caused by compaction. Compaction may result in further environmental costs to society. We present a framework that relates the machinery capacity to soil compaction and its impacts on crop yields and environmental disservices, and associated revenues and costs for farmers and society. We combined simulations using a soil compaction model and a soil-crop model with simple economic analyses. We applied the framework to a case study of cereal production in Sweden, to derive the optimal combine harvester size that maximizes the farmer’s private profit and the societal net benefit, respectively. Increased machinery size decreased harvesting costs, but also reduced simulated crop yields and thus crop revenue as a result of soil compaction. Furthermore, in the model simulations, compaction also increased surface run-off, nitrogen leaching and greenhouse gas emissions. Intermediate machinery size maximized the farmer’s net revenue. Net benefits for society were highest for the lowest possible compaction level, due to the considerable external costs from soil compaction. We show that the optimal machinery size and thus compaction level for maximum farmer revenue would decrease if either producer prices were higher, harvesting costs savings from larger machinery were smaller, or if farmers were charged for (part of the) environmental costs

A framework for modelling soil structure dynamics induced by biological activity

Acknowledgments: This work was funded by the Swedish Research Council for Sustainable Development (FORMAS) in the project “Soil structure and soil degradation: improved model tools to meet sustainable development goals under climate and land use change” (grant no. 2018-02319). We would also like to thank Mikael Sasha Dooha for carrying out the measurements for the water retention curves shown in figure 4.Peer reviewedPublisher PD

Effect of different crop residue management on soil hydraulic properties - a study in a silt loam soil in Belgium

In recent decades, agriculture is challenged to develop strategies for sustainability which conserve non-renewable natural resources such as soil. Soil improving conservation systems aim at improving soil functions and at the same time ensuring high productivity. Such soil management systems have to be adapted to climate and soil specific conditions, and may include reduced tillage, balanced crop rotation, retention of crop residues, cover crops, and appropriate timing of field operations. Changes in soil functions have huge impacts on environmental flows like hydrology, crop production, solute transfer, and CO2 emission at macroscale. Soil structure is considered as one of the key factors for soil functioning. The effect of different land management on soil structure and consequently on soil hydrodynamics is not fully understood and still under investigation. The main aim of this thesis was to evaluate the effect of crop residue management on soil structure by measuring soil hydraulic properties in pedon and core scale. The agronomic context was different crop residue management in a reduced tillage system. The experimental field is named as Solresidus located in Gembloux, Belgium. Since 2008, the field has been under conservation system. Different residue management includes reduced tillage with incorporation of crop residues (RT-in) and without incorporation (RT-out). A large part of this thesis was methodological development to obtain accurate results from experimentations. Many studies have been made and documented in literature to develop indirect methods to predict soil hydrology from soil water retention curve (SWRC). There is no measuring device available which can determine the SWRC over the entire soil moisture range. Therefore, one of the methodological developments was to obtain complete SWRC by combining three different methods in core scale: X-ray computed microtomography (X-ray CT), HYPROP evaporation and Richards pressure plate method to obtain the entire SWRC. The combination of these methods found well justified to obtain the accurate and complete SWRC. Saturated hydraulic conductivity (Ks), specific connectivity (SC) of soil pores and bulk density of the soil were also measured in core and pore scale. There were soil moisture sensors (capacitance sensors) in the field to observe the soil moisture dynamics in pedon scale. Another important methodological development was to obtain the calibration results with the moisture sensor according to the soil texture and horizons. Calibration results found quite satisfying to get the accurate moisture content of the field; it was also noticed that it could be over estimation of soil moisture without the calibration. Significantly, average higher moisture content was observed by the moisture sensors in RT-in than RT-out during the canopy formation to harvest of winter wheat in 2014. The SWRCs also showed that plant available water content was higher in RT-in than RT-out. SC of soil pores was also significantly higher at the surface soil of RT-in than RT-out. RT-in found to have significant positive effects on soil structure by reducing bulk density, increasing SC, Ks and retention of soil moisture during the observation period of this study. Crop yield was marginally higher and organic matter content was significantly higher in RT-in than RT-out (results from close collaboration). Therefore, reduced tillage with residues incorporation found to have better soil hydraulics together with better crop yield than reduced tillage without incorporation of crop residues.AgricultureIsLif

Recent Advances in the Characterized Identification of Mono-to-Multi-Layer Graphene and Its Biomedical Applications: A Review

The remarkable mechanical, electrical, and thermal capabilities of monolayer graphene make it a wonder substance. As the number of layers in graphene flakes increases to few-layer graphene (number of layers ≤ 5) and multi-layer graphene (number of layers ≤ 10), its properties are affected. In order to obtain the necessary qualities, it is crucial to manage the number of layers in the graphene flake. Therefore, in the current review, we discuss the various processes for producing mono- and few-/multi-layer graphene. The impact of mono-/few-/multi-layer graphene is then assessed with regard to its qualities (including mechanical, thermal, and optical properties). Graphene possesses unique electrical features, such as good carrier mobility, typical ambipolar behaviour, and a unique energy band structure, which might be employed in field effect transistors (FETs) and utilized in radio frequency (RF) circuits, sensors, memory, and other applications. In this review, we cover graphene’s integration into devices for biomolecule detection as well as biomedical applications. The advantages of using graphene in each situation are explored, and samples of the most cutting-edge solutions for biomedical devices and other applications are documented and reviewed

Soil-specific calibration of capacitance sensors considering clay content and bulk density

Soil hydrology research requires the accurate measurement of soil water content. Recently, less expensive capacitance sensors (CS) have become popular for the measurement of soil moisture across soil profiles, but these sensors need to be calibrated for precise results. The purpose of the present study was to determine the effect of clay content and bulk density (ρb) on the calibration of CS. Two different CS (10HS and 5TM) were considered for the study. Clay content and ρb of the soils were determined from two different sites and from three different depths (0–5, 25–30 and 50–60 cm) of an experimental field in Gembloux, Belgium. Custom calibration (CC) equations were developed using packed soil columns following the same ρb at sequential volumetric water content (θ) levels. The factory-supplied calibration (FSC) showed an overestimation of θ (0.04–0.07 m3 m–3) with the 10HS sensor, and an underestimation of θ (0.06–0.077 m3 m–3) with the 5TM sensor for the entire calibration range. The variance in raw sensor outputs for different ρb and clay content of soil depths was not highly significant because the soil had limited range of variability in ρb and clay content. However, the CC is recommended in parallel with FSC for the precise measurement of soil moisture with CS. </jats:p