Soil Disturbance Research Articles

Validação das medições automatizadas das variáveis de mobilização do solo com sensores laser e ultrassom

ABSTRACT The quality of soil tillage can be measured with a specific device called profilometer, which provides information on roughness, mobilized area, blistering, and thickness in disturbed soils. However, it is an outdated device, requiring many hours of field and office work. Thus, the objective of the present work was to develop an electronic profilometer using laser triangulation and ultrasound sensors for measurement of digitally mobilized soil profile. The results obtained were compared to those acquired with a conventional sliding bar profilometer to evaluate the accuracy and efficiency of the sensors. The experiment was conducted in a completely randomized design under a controlled environment. The variables were measured seven times using the three profilometers (laser, ultrasound, and conventional) in the original, elevated, and mobilized soil profiles. The electronic profilometer with ultrasound differed in all the measurements when compared to the conventional profilometer, which differed from the laser sensor only in modified roughness.

The Current Status of Weed Resistance to Herbicides and The Discovery of New Herbicides With Novel Modes of Action Necessary to Combat Them

In 2016 and after retiring from a fulltime career in Herbicide Research and Development, I wrote an article for Outlooks addressing the question ‘Can we expect new herbicides with novel modes of action in the foreseeable future?’ and I would like to use this editorial to investigate if we are any closer to answering this question which is important because of the increasing problems of weeds evolving resistance to existing herbicides. Weed management is still essential to maximise crop yields in agriculture. Yield losses of up to 40% across the major global food crops can occur without effective weed control, due to competition between the weeds and crops for nutrients and light, as well as interfering with crop harvest and quality. Herbicides are essential tools in integrated weed management (IWM) but their effectiveness is being eroded due to widespread weed resistance, in part due to overuse of the limited number of herbicide products currently available to the grower. Cultural methods for control of weeds such as, changing rotations, use of cover crops; deep ploughing; manual removal of weeds and chemical mulching are clearly part of the IWM toolbox. However, deep ploughing (and any type of physical disturbance of soil) and chemical mulching, whilst potentially effective, are not applicable throughout global crop production and also are not sustainable environmentally friendly options. Similarly, other non-chemical methods, such as electro-physical and heat treatments including high energy light, boiling water, steam, fire, flame weeding and hot foam have been sold as having potential to replace herbicides, but I question their suitability in main stream row-crop agriculture and also the environmental impact of their use, particularly if they would be regulated as herbicides and needed the extensive catalogue of ecotoxicology studies to investigate adverse effects on non-target organisms and environmental fate studies. Biological approaches are receiving increasing interest in pest management for control of diseases and insects, but these appear not to be an option for weed control.

Evaluating soil water dynamics under a no-tillage system with residual plastic film mulching in an arid region of western China using HYDRUS-2D

No-tillage (NT) with residual plastic film mulching from an earlier year (NTR) is considered an excellent agricultural strategy in arid regions, recommended to reduce not only soil disturbance but also plastic film residues. However, the soil water dynamic in the root zone under this management is more complex due to variations in soil properties and upper boundary conditions. Soil compaction and a disintegrated fraction (DF) of the residual plastic film increase in NTR years. Soil water movement under NTR is not fully understood. It is also necessary to determine a suitable number of NTR years and optimize irrigation to increase water use efficiency (WUE) and maintain sustainable agricultural development. Therefore, the HYDRUS-2D model was calibrated and validated using experimental data from 2019 to 2021 collected in the corn field with conventional tillage (CTN), NT with a new plastic film (NTN), and NTR. The soil water contents (SWC), cumulative water fluxes (CWF), and soil water balances under CTNH, NTNH, and NTRH with the high (subscript H) irrigation depth of 315 mm (the local recommendation) were evaluated using both measured and simulated data. The results for NTRH, NTRM (a medium irrigation depth of 252 mm, 80% of local recommendation), and NTRL (a low irrigation depth of 189 mm, 60% of local recommendation) scenarios were compared, and a suitable number of NTR years was determined. The results of numerical simulations agreed with observations, with the mean relative error range for the calibration and validation periods between 4.9% and 5.4%. The larger number of experimental NTR years, the larger the SWC differences for all irrigation depths, tillage practices, and mulching due to larger soil compaction under NT and a higher DF of the residual plastic film. The largest SWC differences occurred in the 0–30 cm soil layer in the third experimental year (2021), with an average SWC decrease of 2.3% for NTNH compared to CTNH and 10.2% for NTRH compared to NTNH. Simulated two-dimensional SWC distributions further confirmed these experimental results. There were lower CWF under NT and new film mulching. CWF at a depth of 30 cm was 8.5 mm lower for NTNH than for CTNH in 2021. There was a 4.2%, 30.1%, and 43.1% increase in CWF for NTRH compared to NTNH due to higher soil evaporation evaluated from the soil water balance in 2019, 2020, and 2021, respectively. The scenario simulation results showed that SWCs decreased linearly with an increase in DF and that DF of 30% can be regarded as the maximum value for obtaining high WUE under NTR. The highest WUE of 28.3 kg ha–1 mm–1 under NTR during two years was found when the local recommended irrigation depth was reduced by 20% (to 252 mm). Therefore, this management can be recommended in arid regions to avoid plastic pollution with higher WUE.

Enchytraeids in imported soil and organic deposits in Pyramiden, an abandoned mining town on Spitsbergen in the High Arctic

In Arctic soils, potworms (Clitellata: Enchytraeidae) are a particularly important decomposer group. There are relatively many faunistic records from the Svalbard archipelago, in particular its main island Spitsbergen, but few ecological studies on enchytraeids. With climate change and increasing tourism, the introduction and subsequent spreading of exotic species might pose a threat to native biotic communities. In Pyramiden, a Russian (formerly Soviet) coal mining settlement on Spitsbergen abandoned in 1998, Chernozem soil from southern Russia or Ukraine had been imported in 1983 to create lawns. Today the long central lawn presents an environmental gradient: on one end rather shallow humus-rich soil is fertilized by a sea bird colony on an adjacent building, the central part has a rich organic horizon topping humus-rich mineral soil, whereas on the other end humus-rich soil is covered by deposited mineral soil. In August 2018, we sampled this gradient to study the enchytraeid assemblage. Additional samples were also taken within frames with a vigorous grass turf in front of residential houses and in a vegetated heap of decomposing organic material (mostly woodchips). The objectives were to see (1) if and how the differences between habitats would be reflected by changes of the enchytraeid assemblages and (2) if there were any potentially introduced species. Almost 3700 specimens were identified and 9 species were recorded, which is high for habitats of the High Arctic. One species, Enchytraeus buchholzi s.l., had been recorded before in the archipelago only once, also in imported soil. This small-bodied euryoecious r-strategist is abundant in agricultural and other disturbed soils. Molecular barcoding and comparison with sequences from Central Europe showed close resemblance to several specimens, which makes an introduction with the transferred Chernozem highly probable. Most enchytraeids were concentrated in the upper 3 cm of soil (even if mineral), only in the organic deposits vertical distribution was rather even down to 12 cm depth. Numbers in the organic deposits were exceedingly high (ca 417,000 individuals/m2) and E. buchholzi s.l. represented ca 90 % of all specimens. Ordination (NMDS) showed all habitats to host rather distinct assemblages. Spearman's rank correlation showed significant positive correlation of species richness with conductivity and total nitrogen and of abundance with phosphorous and potassium contents in aqueous solution.

Discrete Element Method Simulation and Field Evaluation of a Vibrating Root-Tuber Shovel in Cohesive and Frictional Soils

Soil-cutting forces are key indicators of root-tuber harvesters and other soil-engaging tools’ performance. To improve operational efficiency, minimise soil disturbance, and reduce fuel consumption, the draught and vertical forces involved in root and tuber crop harvesting must be minimised. Two field experiments assessed the harvester’s performance at a depth of 200 mm, varying frequencies, and travel speeds on clay and sandy loam soils. Discrete element models (DEM) were developed and subsequently used to replicate the field experiments and evaluate S-shaped and fork-shaped shovels. Linear regression and ANOVA (p < 0.05) were used to analyse the data. Draught force concurrently increased with speed in both soil textures but decreased with vibration frequency. The draught force decreased by approximately 41% in clay soil and 21% in sandy loam soil when the harvester was operated between 5 Hz and 14.5 Hz and between 10 Hz and 12.5 Hz, respectively. DEM simulations had relative errors of 4% (clay) and 4.7% (sandy loam) for draught force and drawbar power compared to experimental data. The S-shaped shovel was more efficient at crushing and translocating soil–crop mass to the rear of the harvester than the fork-shaped shovel. These DEM soil–crop models are reliable for evaluating other root-tuber harvesting tools.

Real-time emission characteristics, health risks, and olfactory effects of VOCs released from soil disturbance during the remediation of an abandoned chemical pesticide industrial site.

Volatile organic compounds (VOCs) released along with soil disturbance during the remediation of abandoned industrial sites have attracted great attention due to their possible toxicity and odour. However, the real-time emission characteristics of these VOCs and their subsequent effects on health and olfaction are less understood. In this study, the gaseous VOCs released from soil disturbance by excavators and drilling rigs at an abandoned chemical pesticide plant were monitored online with a laboratory-built single photoionization time-of-flight mass spectrometer (SPI-TOFMS). Twelve main VOCs with total mean concentrations ranging from 2350 to 3410 μg m-3 were observed, with dichloromethane (DCM) having a significant contribution. The total concentrations of the remaining 11 VOCs increased substantially during soil disturbance, with the total mean concentrations increasing from 18.65-39.05 to 37.95-297.94 μg m-3 and those of peak concentrations increasing from 28.46-58.97 to 88.38-839.13 μg m-3. This increase in VOC concentrations during soil disturbance leads to an enhanced heath risk for on-site workers. The distinctive difference between the mean and peak concentrations of VOCs indicates the importance of using mean and peak concentrations, respectively, for risk and olfactory evaluation due to the rapid response of the human nose to odours. As a result, the cumulative noncarcinogenic risk at the relatively high pollutant plot was higher than the occupational safety limit, while the total carcinogenic risks at all monitored scenarios exceeded the acceptable limit. Among the VOCs investigated, DCM and trichloroethylene (TCE) were determined to be crucial pollutants for both noncarcinogenic and carcinogenic risks of VOCs. With regard to olfactory effects, organic sulphides, including dimethyl disulphide (DMDS), dimethyl sulphide (DMS), and dimethyl trisulphide (DMTS) were identified as dominant odour contributors (78.28-92.11%) during soil disturbance.

Characteristics of labile organic carbon fractions under different types of subsidence waterlogging areas in a coal mining area: A case study in Xinglongzhuang Coal Mine, China

The restoration of subsidence waterlogging areas has the potential to facilitate carbon accumulation in coal mining areas with high ground water tables. However, the soil organic carbon (SOC) and labile organic carbon (LOC) have not been sufficiently investigated in different types of subsidence waterlogging areas. In this study, SOC and LOC fractions, including light fraction organic carbon (LFOC), particulate organic carbon (POC), and dissolved organic carbon (DOC) within 0–50 cm soil profiles, were determined in a reference cropland (RC) and three types of subsidence waterlogging area in Xinglongzhuang Coal Mine, Shandong Province, China, including an aquaculture waterlogging area (AWA), deep waterlogging area (DWA) and shallow waterlogging area (SWA) with water depths of 1.8, 3.2, and 0.65 m, respectively. Compared with RC, SOC and LOC decreased by 4.13%, 25.03%, and 77.91% in SWA, DWA, and AWA, respectively. The largest depletion was in the 0–10 cm layer, indicating that there was a time lag for the recovery of the total functional pools of SOC after subsidence. The lability of POC was highest among the three types of LOC fractions, indicating that mining subsidence triggered soil redistribution and impacted on carbon accumulation. With comparatively little soil profile interference in DWA and SWA, the lability of LFOC and POC decreased with soil depth, while the DOC increased. There was a large discrepancy in AWA, with the lability of LOC fractions fluctuating because of soil disturbance by intensive engineering. The LOC fractions were closely associated and correlated with soil properties, especially total nitrogen (TN) and total phosphorus (TP). Restoration and management of the subsidence waterlogging areas have a vital impact on the SOC pool. It was concluded that shallow water and a natural geomorphology-based topography, with little soil disturbance, well-developed vegetation communities, and continuous monitoring of soil and water properties would facilitate the carbon accumulation process.

Do feral pigs increase soil erosion? A monsoonal northern Australia case study

AbstractAnimals are recognised biological agents that can turn over large amounts of soil, influence soil structure and composition and may allow soil to more easily erode. Feeding activities of feral pigs (Sus scrofa) are known to produce considerable soil disturbance. Here, pig disturbance, together with soil erosion and deposition patterns, are quantified along two hillslope transects in northern Australia over 10 years. Annual disturbance by pigs was ~1% of surface area. The erosion rate was low with a range of 0.008–0.13 mm year−1. Both transects had similar hillslope profiles, vegetation patterns and similar appearance. There was a greater number of pig disturbances, area and mass of material disturbed by pigs for one transect compared to the other moving downslope. However, for the second transect, the number of disturbances significantly decreased moving downslope while the mass of material exhumed remained relatively constant along the hillslope. For the first transect, this suggests that the greater number of pig digs moving downslope reduces hillslope connectivity and therefore reduces erosion. That is, the greater the amount of disturbance by pigs, the less erosion. The pig digs produce a pit and a mound with the material diffusing locally and the pit capturing material from upslope reducing hillslope connectivity. These pits have been observed to last many years. A control on pig disturbance was likely to be rock content. The average surface rock content of the two transects was significantly different (9% and 20%, respectively) and with the higher rock content reducing pig disturbance and erosion for the second transect. The bio geomorphic influence that pigs represent in the landscape for biogeochemical cycling requires ongoing investigation.

Collembola taxonomic and functional diversity in conventional, organic and conservation cropping systems

Intensive agriculture has been demonstrated to be a main threat to soil biodiversity through physical and chemical disturbances of soil. Alternative systems based on lower disturbances may help to promote soil biodiversity and its role in soil functioning. However, the effects of alternative systems on soil biodiversity are still poorly understood, especially regarding soil mesofauna. In this study, we aimed to assess the effects of alternative cropping systems and practice intensity on the taxonomic and functional diversity of Collembola. Collembola were sampled for two consecutive years in 21 fields (3 plots per field) under conventional or alternative systems, namely conservation or organic systems either stable (≥7 years) or in transition (≤3 years). Indicators and indices were computed to characterize separately tillage, pesticide treatments and organic fertilization in each field. Collembola species and functional traits were investigated. Functional diversity of Collembola was assessed using species traits (i.e. traits from the literature) and by conducting length measurements directly on collected Collembola individuals (body, head, leg, antenna and furca length). Collembola diversity was highly variable between and within cropping systems and years. Species richness was notably higher in conservation than in conventional systems in the second year of the study. More specifically, low tillage and high pesticide treatment intensities increased taxonomic and functional diversity and affected species with traits adapted to the surface (i.e. scales, trichobothria). Measured Collembola body length additionally revealed the presence of larger individuals under low tillage and high pesticide treatment intensities, with similar results for other length traits. Overall, our results revealed that 1) taxonomic and functional diversity are complementary to understand the effects of agricultural practices and systems on Collembola and 2) measurement of body length is relevant to assess the effects of disturbances on the local Collembola community.

Influence of silvicultural practices in northern hardwood forests on a long-lived perennial herb, Trillium cernuum L.

Contemporary and predicted declines in tree species diversity and forest resilience have prompted renewed interest in even-aged systems and/or site preparation to overcome bottlenecks to tree recruitment or facilitate range expansion of future-adapted species. The impact of this intensification on the herbaceous layer in forests traditionally managed with uneven-aged systems, however, is unclear, especially for uncommon dispersal limited species with heterogenous distributions. We leveraged a large-scale experiment (the Northern Hardwood Silvicultural Experiment to Enhance Diversity) to investigate the response of Trillium cernuum L., a somewhat uncommon and heterogeneously distributed non-clonal herb in our study system, to a gradient of canopy removal and soil disturbance. We monitored 16 small populations from 2015 (the year prior to treatment) to 2019 (3-years post treatment). Our results suggest that initial population size and stage structure were inextricably coupled with T. cernuum response. Independent of treatment, T. cernuum abundance and flowering generally increased over time commensurate with initial population size. Moreover, our study highlights the confounding effect of deer herbivory, which increased significantly following treatment. Collectively, our findings suggest that T. cernuum populations were resilient to canopy disturbance associated with single-tree selection and shelterwood harvests and the levels of scarification applied as part of our study. Higher levels of site impact or other site preparation methods such as herbicides will likely have greater impacts and warrant further investigation. Our results also suggest that directly monitoring populations of interest may be necessary to quantify treatment effects for uncommon and/or heterogenous species that are missed with common plot-based sampling designs or of conservation concern.

Recent Applications of Smart Technologies for Monitoring the Sustainability of Forest Operations

Precision forestry is a useful technique to help forest stakeholders with proper sustainable forest management. Modern sensors and technologies, with special reference to the sustainability of forest operations, can be applied on a variety of levels, including the monitoring of forest activities regarding the three pillars (economy, environment, and society). In this review, we summarised the current level of knowledge regarding the use of precision forestry techniques for monitoring forest operations. We concentrated on recent data from the last five years (2019–2023). We demonstrated how an Industry 4.0 strategy for remote and proximal monitoring of working performance can be effective when using CAN-bus and StanForD data collected by modern forest machines. The same information can be effectively used to create maps of soil trafficability and to evaluate the patterns of skid tracks or strip roads built as a result of forest intervention. Similar information can be gathered in the case of small-scale forestry by using GNSS-RF (Global Navigation Satellite Systems—Radio Frequency) or even monitoring systems based on smartwatches or smartphones. LiDAR and Structure for Motion (SfM) photogrammetry are both useful tools for tracking soil rutting and disturbances caused by the passage of forest machinery. SfM offers denser point clouds and a more approachable method, whereas laser scanning can be considerably faster but needs a more experienced operator and better data-processing skills. Finally, in terms of the social component of sustainability, the use of location sharing technologies is strongly advised, based for instance on GNSS—RF to monitor the security of forest workers as they operate.

Study on the Mechanism of Motion Interaction between Soil and a Bionic Hole-Forming Device

Due to the lack of water resources, the main agricultural planting method used in the northwest region of China is plastic film mulching, with precision hole sowing performed on the film after mulching. However, conventional hole-forming devices damage the compactness of the soil hole while moving on the plastic film, causing seed misplacement. Therefore, this study designed a bionic hole-forming device based on the oriental mole cricket. In order to explore the interaction between the hole-forming device and the soil, a typical soil discrete element particle model was established, and its contact parameters were calibrated. An experiment was conducted to compare the performance of the bionic hole-forming device with a conventional device using discrete element method and multi-body dynamics (DEM-MBD) coupled simulations. The results revealed that the bionic hole-forming device caused less soil disturbance during the hole-forming process and could reduce the sowing operation resistance compared to the traditional device. Compared to traditional square and cone-shaped hole-forming devices, the soil resistance of the bionic hole-forming device was the smallest, at 7.51 N. This work provides a reference for the optimization of hole-forming devices for plastic film sowing.

Impacts of organic matter amendments on urban soil carbon and soil quality: A meta-analysis

Organic matter amendment application is an important avenue of beneficial waste diversion and is used to improve soil quality in agricultural and urban settings. In urban regions, amendments are used to support local food production, maintain vegetation for landscaping and recreational use, and reclaim disturbed soils. Urban regions generate large quantities of wasted organic resources for potential application aiding in creating a circular nutrient economy. There is a growing interest in understanding the effects of amendments such as compost, biosolids, and biochar on soil properties in agricultural settings. Gaps remain, however, in assessing their effects in urban land uses. We conducted a literature review to assess the effects of compost, biochar, and biosolids on soil carbon and soil quality of urban soils managed for gardening, landscaping, recreation, and reclamation. Application of organic matter amendments led to an average increase of 3.6 units of soil organic matter% (SOM%). Compost and biochar improved SOM% the most, by 3.1 and 6.5 units of SOM%, respectively. Biosolids resulted in the smallest increase in SOM% but had greater nutrient benefits than other amendments. Parameters related to chemical and physical soil quality improved with the application of amendments. Gaps in the literature remain, such as assessing urban gardens, soil to depths greater than 30 cm, and the persistence of SOM in amended soils. This meta-analysis proposes that organic matter amendments are a powerful means to improve soil quality in urban regions, provide vital cobenefits to surrounding communities, and increase soil carbon storage.

Conservation Tillage in Medicinal Plant Cultivation in China: What, Why, and How

Ecological cultivation is a promising regime for medicinal plant production. For a long time, unreasonable farming methods have threatened soil health and medicinal agriculture and restricted the sustainable development of ecological agriculture for medicinal plants. However, there is a lack of comprehensive discourse and discussion about the pros and cons of different tillage regimes. Here, the research trend and application prospects of no-tillage (NT) are comprehensively reviewed, and the ecological benefits, challenges, and opportunities of the NT system in ecological agriculture of medicinal plants are scrutinized, aiming to call for an about-face in the sustainable conservation and utilization of both phytomedicine resources and agricultural/ecological resources. An exhaustive literature search in PubMed, Bing, Scopus, and CNKI was performed to outline the research trend in conservation tillage and medicinal plants during the recent four decades. The application of NT has a long history and can reduce tillage frequency and intensity and protect soil from erosion and deterioration. NT is often combined with organic mulch to significantly reduce soil disturbance. NT and stover mulching have the advantages of saving manpower and resources and improving soil quality, crop yield, and quality. The ecological and economic benefits of NT in long-term medicinal plant cultivation could be prominent. In developing medicinal plant cultivation, competing with food crops should be avoided as much as possible, and the impact on the production of major grain crops should be minimized. Therefore, the full utilization of soil resources in forests, mountains, and wasteland is advocated, and sustainable soil utilization is the core issue in the process of land reclamation. NT and stover mulching not only inherit the traditional concept of “natural farming”, conform to the basic laws of ecology, as well as the growth characteristics of medicinal plants, but also protect the ecological environment of the production area. It would become the core strategy of ecological agriculture for medicinal plants. Our summary and discussions would help propose countermeasures to popularize NT and organic mulch, promote relevant research and scientific allocation of resources, and adapt to local conditions to achieve precise management and harmonize conservation and production of medicinal plants.

Effects of biochar additions on the mechanical stability of soil aggregates and their role in the dynamic renewal of aggregates in slope ecological restoration

Mechanical stability of soil aggregates is important for resisting external disturbances in slope soils. Biochar (BC) is widely used in slope remediation. However, biochar application may not be conducive to the formation of mechanical-stable soil aggregates, and the effects of biochar additions on the mechanical stability of soil aggregates in slope restoration remain largely unclear. In this context, an incubation experiment was conducted in this study with four biochar levels added to artificial soil, namely 0 % (BC0), 1.5 % (BC1), 3 % (BC2), and 4.5 % (BC3), corresponding approximately to 0, 0.77, 1.53 and 2.30 M ha−1, respectively. The contributions of different soil aggregate fractions to maintaining the mechanical stability of aggregates, as well as the main influencing factors and pathways of biochar additions on soil aggregate stability in a dynamic renewal process of aggregates, were investigated in this study. The results showed a decreasing trend in the mean weight diameter (MWD) with increasing biochar levels and BC1 has no significant difference with BC0, showing MWD values of 2.74 and 2.75, respectively. In contrast, BC3 is significantly lower MWD value of 2.18. The BC3 exhibited negative impact on the mechanical stability of the aggregates. Redundancy analysis (RDA) showed that large macroaggregates (>5 mm) exhibited a stronger contribution on the aggregate mechanical stability between all soil aggregate fractions. The random forest (RF) algorithm and structural equation modeling (SEM) indicated that microaggregate-associated soil organic carbon (SOC) contents and soil pH values were the main factors driving the changes in the aggregate mechanical stability caused by biochar applications. Indeed, the biochar level of 1.5 % maintained the stability of macroaggregates and increased the microaggregate-associated SOC content by 35.7 %, which was conducive to the formation of microaggregates within macroaggregates. Our study suggests that the application of biochar at a level of 1.5 % is more beneficial for maintaining the mechanical stability of artificial soil aggregates.

Crop rotation and cultivation effects on Convolvulus arvensis population dynamics in small grain organic cropping systems

Convolvulus arvensis L. Scop. (field bindweed) is a difficult weed to manage in organic cropping systems. Convolvulus arvensis suppression often requires intensive tillage and cultivation practices that have negative impacts on soil quality. To improve C. arvensis management in organic, small grain cropping systems, we compared ten cropping system treatments in a field trial from the autumn of 2017 until harvest of 2020 in Corvallis, MT, USA. Cropping system treatments varied along a gradient of tillage and crop competition, with tillage intensity and competition inversely related. High soil disturbance and no competition occurred in two treatments that remained in tilled fallow for two consecutive years. Six cropping system treatments had different combinations of tillage and annual or biennial crops, including wheat and forages. Two treatments had minimal soil disturbance and maximum competition from two consecutive years of perennial alfalfa. Convolvulus arvensis ramet density was counted annually to estimate changes in treatments over time. Differences in soil chemical and physical properties between treatments were also assessed in the final years of the study. In the first two years, there was no difference in C. arvensis ramet density among cropping system treatments. In the final two years of the study, C. arvensis density remained below one ramet per m2 in intensively tilled fallow treatments and perennial alfalfa treatments, but was much more variable in treatments with more diverse annual and biennial crop rotations with minimal to moderate tillage. The only differences between treatments in soil physical and chemical properties was aggregate stability. Soil from the most intensively tilled fallow treatments had lower soil aggregate stability than six other treatments, indicating higher erosion potential. Our results suggest that annual cropping systems can lead to increased C. arvensis density. Incorporating a perennial forage or an intensively tilled fallow period can prevent C. arvensis expansion in small grain organic cropping systems, but the perennial forage can protect and enhance soil quality.

Knowledge domain and research progress in the field of crop rotation from 2000 to 2020: a scientometric review.

As one of the most fundamental and prevalent agronomic practices, crop rotation is of great significance for the optimization of regional planting structure and sustainable agricultural development. Therefore, crop rotation has attracted continuous attention from both researchers and producers worldwide. In recent years, many review articles have been published in the field of crop rotation. However, since most reviews usually focus on specialized directions and topics, only few systematic quantitative reviews and comprehensive analysis can fully determine the state of research. To address this knowledge gap, we present a scientometric review to determine the current research status of crop rotation by using CiteSpace software. The main findings were as follows: (1) From 2000 to 2020, five knowledge domains were identified as representing the intellectual base of crop rotation: (a) synergism and comparison of conservation agriculture measures or other management measures; (b) soil microecology, pest control, weed control, and plant disease control; (c) soil carbon sequestration and greenhouse gases (GHGs) emissions; (d) organic crop rotation and double cropping patterns; and (e) soil properties and crop productivity. (2) Six notable research fronts were identified: (a) plant-soil microbial interactions under crop rotation; (b) integrated effect with minimum soil disturbance and crop retention; (c) carbon sequestration and GHG emission reduction; (d) impact on weed control; (e) heterogeneity of rotation effects under different weather and soil conditions; and (f) comparison between long-term and short-term rotation. Overall, this study provides a comprehensive overview of crop rotation and proposes some future development trends for the researchers.

Red wood ants (Formica rufa) help propagate invasive small balsam (Impatients parviflora) in accordance with the directed dispersal hypothesis

Ants are a major source of soil disturbance and can influence vegetation dynamics and biodiversity by changing environmental conditions. Their seed collection activity supports dispersal and can favour the presence of species, including introduced, non-native and invasive species. Understanding of seed dispersal mechanisms is important for predicting plant distributions and invasive risk.Studies generally addressing myrmecochory have mostly focused on interactions between native species and few have considered the role of ants in spreading non-native plants. This study investigated effects of a native species Formica rufa (red wood ant) on the distribution of the invasive plant, Impatiens parviflora DC (small balsam). The study measured ant seed collection activity and plant and soil chemical characteristics to evaluate whether assumptions of the directed dispersal hypothesis obtained.Seed collection experiments showed that ants do not selectively collect small balsam seeds but collect them randomly at about the same rates as other organic and inorganic material. Non-targeted collection however suffices in dispersing small balsam seeds in or near the ant nest thus enhancing plant establishment, growth and reproduction.I. parviflora density in the forest floor was 3.06 plants per m2 while I. parviflora density reached 82.68 plants per m2 in and around ant nests I. parviflora individuals growing on nest mounds were significantly larger, showed more flowers and produced more seeds than plants established on the surrounding forest floor. Better growth of I. parviflora on and around ant nests corresponded with significantly higher nutrient content, especially of nitrates and available phosphorus in ant nests. Ant nests also showed higher pH values and available potassium, sodium and calcium.This study thus found that red wood ants contribute to the expansion of I. parviflora by soil transformation and non-targeted seed dispersal in an otherwise nutrient-poor environment where the plant would otherwise struggle to flourish.

Nematode abundances and community diversity under energy crop (maize and sainfoin) cultivation in annual and perennial cropping systems

Despite conservation efforts and increased awareness, the loss of soil biodiversity goes on across a wide range of ecosystems. Since soil function and structure depend mainly on the state of the biological communities, the soil quality assessment and disturbance in annual vs. perennial cropping systems is done with the help of indicators such as nematodes. Agricultural practices like mix cropping causes variations in the taxonomic abundance of soil nematode communities. This field experiment aimed to assess the overall effect of annual and perennial energy crops (maize: Zea mays and sainfoin: Onobrychis viciifolia) on the nematode communities under pure and mixed cultivation. Sainfoin had the highest nematode abundance, followed by the mixed culture and maize. Out of 38 identified genera, 19 were identified under maize, 31 under perennial sainfoin, 28 under annual sainfoin, 28 under perennial mixture, 20 under the annual mixture and 13 co-existed among these treatments. Of all the trophic groups, the bacterivores were the most abundant (738), followed by plant-parasitic nematodes (272), omnivores (230), fungivores (84), and carnivores (33). Nematode abundance was lower under the annual than perennial plots of both sainfoin and the mixed culture. The perennial plots were dominated by plant-parasitic nematodes. Our results support the idea that soil nematodes should be considered for inclusion in indices of soil quality through their contribution to soil processes. Also, soil nematodes and energy crops like sainfoin may increase the functional properties of agricultural ecosystems and allow better productivity and sustainability.

Roman to early medieval cereal farming in the Rhineland: weeds, tillage, and the spread of the mouldboard plough

ABSTRACT A new model for gauging levels of soil disturbance (i.e. tillage) by analysing arable weed assemblages from archaeological contexts is applied to an extensive Roman-to-early medieval archaeobotanical sequence from the region west of Cologne. It tests the hypothesis that increasing use of the mouldboard plough, especially in a three-field system, would result in increased levels of soil disturbance which would be reflected in the kinds of weeds that grew in arable fields. The results point to clear differences in tillage regimes during the Roman period, providing support for the view that military sites were not provisioned by the same networks that supplied the civilian market. They also reveal generally low disturbance levels for the fifth and sixth centuries, indicating a continuing predominance of ard cultivation in the post-Roman period. The majority of seventh- to eighth-century samples had, however, been grown in ‘high disturbance’ conditions, a pattern that continued through the eighth and ninth centuries. Although use of the mouldboard plough within a fully developed three-field system may not have become widespread until the tenth or eleventh century, our evidence suggests that a plough capable of turning over the soil was in use in the Rhineland at a much earlier date.