Reduced Soil Disturbance Research Articles

Highway to health: Microbial pathways of soil organic carbon accrual in conservation farming systems

Increasing pressure on arable land related to climate change mitigation and adaptation within recent policy frameworks has generated widespread interest in the effect of sustainable agricultural management practices on soil organic carbon (SOC) storage. Current frameworks point to soil microorganisms and their functioning as the key drivers of SOC accrual. This study provides a comprehensive on-farm assessment of changes in SOC formation pathways (physico-chemical and microbial) and the underlying drivers comparing three soil use systems: conservation and conventional farming systems as well as permanently vegetated adjacent reference soils (i.e., field margins) without agricultural land-use.Overall, our results indicated substantial increases in extractable organic carbon (+22 %), microbial biomass carbon (+29 %) and necromass carbon stocks (+11 %) in soils of conservation farming systems as compared to conventional farming systems. Differences between all three soil use systems were strongly pronounced in the surface soil (0–5 cm) and declined in deeper soil layers. Structural equation modelling revealed a varying influence of SOC storage pathways among soil use systems, with microbial-mediated (‘in-vivo’) turnover and direct sorption being the most dominant pathways. Moreover, diversity of crop rotation and tillage intensity were identified as the most important factors influencing extractable organic carbon and carbon-liberating enzyme activity within conservation farming management. Our on-farm approach demonstrates that enhanced bioavailable carbon inputs and reduced soil disturbance are the key drivers for microbially-controlled SOC accrual in arable soils and that conservation farming systems with extended plant coverage and increased crop diversity can substantially advance the restoration of soil health.

Phosphorus lability in a Ferralsol as affected by land-use change in the Brazilian Cerrado

ABSTRACT Low availability of phosphorus (P) is a constraint to agricultural development in tropical soils, owing to the high fixation of P in the soil matrix. Land-use change can modify soil P dynamics. This study aimed to evaluate the effects of land-use change on P fractions in a Ferralsol under different systems of use and management. Inorganic (Pi) and organic soil P (Po) fractions were assessed by sequential fractionation using H2O, NaHCO3, NaOH, hot concentrated HCl and H2SO4-H2O2 as extractants. The systems in the study were as follows: pasture (PAST), no-tillage system (NT), organic cultivation (ORG) with 2, 6, 8 and 10 years of organic management, and conventional continuous cropping tillage (CT). A native Cerrado forest (F) area was used as reference. In general, Po forms predominated over Pi, with exception of the CT soil, where Pi represented 41% of the total P. On average, conversion of F into the CT system reduced levels of Po in the soil by up to 72%. The soil P resilience index showed that P inputs in the CT and NT systems were insufficient at recovering P availability after the land-use change. On the other hand, the most recent ORG systems demonstrated the greatest efficiency at restoring the equilibrium of the soil P state. The hypothesis that less intensive agricultural systems increase the soil labile P pool, enhancing available P levels, was confirmed. Agricultural systems that used organic inputs and reduced soil disturbance were found to be more efficient at recovering and maintaining soil P availability.

Using pack animals instead of tractors in Central Italy's protected areas: No evidence of reduced soil disturbance

In thinning operations in Mediterranean beech forests, pack animals are often used when topographic conditions do not allow for the use of mechanisation to perform logging operations. Otherwise, mechanised extraction is the primary choice. In an effort to reduce soil disturbance caused by mechanised ground-based logging, the forest authorities who guard protected areas have been mandating animal logging at all logging sites in recent years. Since no comparative scientific trials of soil disturbance of these two extraction systems have ever been conducted in the target setting, there is no scientific evidence to sustain this approach. On this basis, we chose two study areas where the forest authorities mandated animal logging. Each study area consists of three sub-compartments, one unharvested, one harvested by animals, and one harvested by tractor in the same year (2021). We examined soil compaction, soil organic matter, and soil microarthropod biodiversity in animal skid trails, tractor skid trails, soil unaffected by extraction methods, and unharvested control sites in each study areas. We used linear mixed-effects models, indicating the study area as random intercept, to investigate the effect of the experimental treatments on the target soil features, and to check the relationship among soil physico-chemical parameters and soil microarthropod biodiversity. We discovered that only the animal and tractor skid trails showed signs of disturbance in terms of soil compaction and organic matter loss. Additionally, there was a significant decline in the biodiversity of soil microarthropods in both the skid trail types, with values of the QBS-ar index which were practically halved in comparison to the control area. We did not find any significant difference in the values in the tractor and animal skid trails for any of the examined soil characteristics. Low soil microarthropod biodiversity was found to be correlated with high soil compaction in terms of penetration resistance and low soil organic matter levels, according to linear mixed-effects models. Despite our preliminary findings, we made it clear that the short wood system by a tractor fitted with forwarding bins is unquestionably a very soil-disturbing extraction system, that ought to be avoided when conducting logging operations in protected areas. However, pack animals are not a suitable solution to reduce soil disturbance. Other extraction systems such as chute, small-scale cable yarders, as well as combination of animals and machine avoiding extensive traffic on the forest soil, are better solutions to the fundamental issue of low-impact logging in protected areas.

Strip Tillage Improves Productivity of Direct-Seeded Oilseed Rape (Brassica napus) in Rice–Oilseed Rape Rotation Systems

Oilseed rape (Brassica napus) is a crucial global oil crop. It is generally cultivated in rotation with rice in southern China’s Yangtze River Basin, where the wet soil and residue retention after rice harvest significantly hinder its seedling establishment. Hence, this study developed a strip-tillage seeder for oilseed rape seeding following rice harvest. Additionally, seedling establishment, soil infiltration and evaporation post-seeding, soil moisture change, oilseed yield, and weed occurrence under strip tillage (ST) were compared with conventional shallow rotary-tillage (SR) and deep rotary-tillage (DR) seeding practices. Compared to SR and DR, the results demonstrated that ST had a higher seeding efficiency and 53.8% and 80.2% lower energy consumption, respectively. ST also enhanced seedling growth and oilseed yield formation more effectively than the competitor tillage treatments, with an oilseed yield increase exceeding 6%. Additionally, ST improved water infiltration and reduced soil water evaporation, resulting in higher topsoil (0–20 cm) moisture during the critical growth stages. Furthermore, ST reduced soil disturbance, significantly decreasing the density of the dominant weed, Polypogon fugax. Overall, ST seeding technology has the potential to improve the productivity of oilseed rape in rice–oilseed rape rotation systems, and its yield superiority is mainly due to seedling establishment improvement and soil moisture adjustment.

Reduced tillage intensity does not increase arbuscular mycorrhizal fungal diversity in European long‐term experiments

AbstractMechanical soil disturbance is one among the key factors influencing soil biodiversity in agriculture. Although many soil organisms are sensitive to soil disturbance, fungi could be highly impacted due to their sessile lifestyle, relatively slow growth and filamentous body structure. Arbuscular mycorrhizal (AM) fungi are of particular interest in arable lands, providing crop plants with numerous vital services such as nutrient acquisition and protection against abiotic and biotic stressors. Considering this, tillage practices that aim to reduce soil disturbance are often seen as a fungal‐friendly alternative to conventional inversion tillage. Although local studies exist on the impacts of minimal tillage practices on AM fungi, the universality of this approach has been debated. Our objective was to assess the effects of reduced tillage intensity on AM fungi in comparison with conventional tillage. Using high‐throughput sequencing techniques in long‐term field experiments in five European countries, we show that the effects of reduced tillage intensity may not necessarily be positive on soil AM fungal diversity. Plots which were tilled using reduced tillage techniques had lower AM fungal richness in three countries, whereas in one of them, no significant differences were found. We also observed a shift in AM fungal communities where prevalence of taxa preferring root colonisation rather than soil exploration increased under reduced tillage regimes. Here, we argue that more detailed and long‐term studies are needed to understand the factors that could make the reduction of soil disturbance more beneficial to AM fungi if agricultural sustainability goals are to be met.

Impact of Mechanized Crop Establishment Techniques on Growth, Yield, and Microbial Dynamics under Rice-Wheat Cropping System: A Review

The rice-wheat cropping system, predominant across the Indo-Gangetic plains, generates a substantial volume of crop residue, with an annual yield of 7-9 tonnes per hectare of rice residue. Effective management of this residue, whether in-situ or ex-situ, has become an urgent necessity. However, the economic feasibility of transporting residue beyond 20 km from the field is limited. Consequently, in-field residue management through the adoption of specialized machinery has emerged as an imperative solution. The narrow window between paddy harvesting and wheat sowing, compounded by labor scarcity during peak periods, underscores the need for mechanized crop establishment techniques. Machines such as happy seeders, super seeders, turbo seeders, spatial drills, and seed-cum-fertilizer drills are crucial tools in this regard. This paper examines the benefits of mechanized crop establishment techniques on wheat growth, productivity, and soil biological health within the rice-wheat cropping system. These techniques have revolutionized agricultural practices by significantly influencing growth dynamics, yield parameters, and microbial ecology. The adoption of precision seed drills and mechanized tillage equipment has transformed traditional farming methods, facilitating efficient seed placement, soil preparation, residue incorporation, and weed management. This has resulted in improved crop growth parameters, enhanced yield dynamics, better root development, increased nutrient uptake, and overall plant vigor. Furthermore, reduced soil disturbance and decreased weed pressure associated with mechanized operations have created a conducive environment for beneficial microbial communities to thrive. The integration of mechanized crop establishment techniques has a positive impact on both crop productivity and sustainability, highlighting their importance in modern agricultural practices within the rice-wheat cropping system of the Indo-Gangetic plains.

Mediterranean farmers’ understandings of ‘good soil management’ and ‘good farmer’ identity in the context of conservation agriculture

ABSTRACT Mediterranean agriculture is increasingly threatened by soil degradation and climate change. Conservation agriculture (CA) is a farming approach characterized by reduced soil disturbance, soil cover, and crop rotation that provides agronomic, economic, and environmental benefits to farmers, but which is not yet widespread in the Mediterranean region. To investigate the sociocultural aspects of CA adoption, we examined farmers’ understandings of ‘good soil management’ and a ‘good farmer’ identity. We employed network analysis to visualize and compare farmers’ mental models of these concepts and how they differed according to farmers’ tillage practices. We found that crop rotation is a prominent concept cognitively tied to fertilizer application, bridging conventional and reduced tillage practices. CA farmers’ mental models of soil management are more complex than conventional farmers’. Demonstrating productivity and having experience and knowledge were the most prominent aspects of farmers’ understanding of a ‘good farmer’. For CA farmers, this was tied to environmental responsibility and innovation, whereas for conventional farmers, a set of best practices including tillage and the use of mineral fertilizers, was valued more highly. CA may compete with held understandings concerning soil management among conventional farmers. CA adoption programmes could be better tailored to align with their cultural values.

Influence of Planting Techniques and Integrated Nutrient Management on Soil Health in Rice (Oryza sativa L.)

The study investigated the impact of different planting techniques and nitrogen management at Sardar Vallabhbhai Patel University of Agriculture & Technology, Meerut (UP) during the rainy (kharif) season of 2019-20 on soil health in rice. Soil samples were collected at two depths, air-dried, and analyzed for aggregate size distribution using wet sieving. Particulate organic carbon (POC) was determined through aggregate slaking, while total organic carbon (TOC) content was assessed using rapid titration. Microbial biomass carbon (MBC) was calculated by incubating soil samples, followed by fumigation-extraction methods. Results revealed that soil pH and electrical conductivity remained unaffected by planting techniques and fertility levels. Aggregate size distribution analysis revealed that the Furrow Irrigated Raised Bed (FIRB) treatment promoted larger macro-aggregates (>2mm) at varying soil depths, while Conventional Tillage (CT) encouraged smaller micro-aggregates. Reduced Tillage (RT) combined with Farmyard Manure (FYM) and chemical fertilizer increased POC and TOC content, emphasizing the importance of reduced soil disturbance and organic matter addition. Conversely, CT exhibited lower POC and TOC levels due to intensive soil disturbance. RT with FYM and chemical fertilizer significantly enhanced soil MBC, highlighting their role in improving soil health and fertility.

Conservation tillage facilitates the accumulation of soil organic carbon fractions by affecting the microbial community in an eolian sandy soil.

Conservation tillage (CT) is an important agronomic measure that facilitates soil organic carbon (SOC) accumulation by reducing soil disturbance and plant residue mulching, thus increasing crop yields, improving soil fertility and achieving C neutrality. However, our understanding of the microbial mechanism underlying SOC fraction accumulation under different tillage practices is still lacking. Here, a 6-year in situ field experiment was carried out to explore the effects of CT and traditional tillage (CK) practices on SOC fractions in an eolian sandy soil. Compared with CK, CT increased the particulate OC (POC) content in the 0-30 cm soil layer and the mineral-associated OC (MAOC) content in the 0-20 cm soil layer. Moreover, tillage type and soil depth had significant influences on the bacterial, fungal and protistan community compositions and structures. The co-occurrence network was divided into 4 ecological modules, and module 1 exhibited significant correlations with the POC and MOC contents. After determining their topological roles, we identified the keystone taxa in the network. The results indicated that the most common bacterial taxa may result in SOC loss due to low C use efficiency, while specific fungal (Cephalotrichum) and protistan (Cercozoa) species could facilitate SOC fraction accumulation by promoting macroaggregate formation and predation. Therefore, the increase in keystone fungi and protists, as well as the reduction in bacteria, drove module 1 community function, which in turn promoted SOC sequestration under CT. These results strengthen our understanding of microbial functions in the accrual of SOC fractions, which contributes to the development of conservation agriculture on the Northeast China Plain.

Enhancing Organic Carbon Content in Tropical Soils: Strategies for Sustainable Agriculture and Climate Change Mitigation

Background: Tropical soils are characterized by low soil organic carbon (SOC) contents, which can negatively impact soil fertility, water retention, overall agricultural productivity, and food security. Objective: This paper aimed to review and synthesize the current body of literature on the restoration of SOC in tropical soils. Methods: A total of about 152 related articles were downloaded from electronic journal databases using search keywords, such as organic carbon (OC), conservation tillage, intercropping, biochar, and tropical soil. We discussed conservation tillage practices, such as reducing soil disturbance and respiration from the soils, as a means to promote soil OC sequestration. We also highlighted the importance of crop residue retention, which not only increases organic matter inputs and soil nutrients but also promotes soil water retention and reduces soil erosion. Results: Cover crops and crop rotation are identified as effective practices to cover bare ground during planting seasons, reduce erosion, and prevent nutrient losses through leaching and runoff. Additionally, we review the role of fertilizer application, manure and compost application, intercropping, agroforestry, and biochar as strategies to enhance OC content in tropical soils. We highlight the benefits of incorporating organic amendments, such as manure and compost, to improve soil structure and water-holding capacity. Furthermore, we discuss the potential of biochar, a carbon-rich material produced from biomass pyrolysis, as a strategy to sequester OC in tropical soils. Conclusion: Overall, this review provides insights into various strategies that can be implemented to increase the OC content of tropical soils, which can have multiple benefits for soil health, agricultural productivity, and climate change mitigation. Further research and implementation of these practices can contribute to mitigating climate change, conserving soil resources, and promoting sustainable agriculture in tropical regions.

Assessment of roadside grassland soil carbon characteristics

Carbon is a vital component of soil health and plays a crucial role in supporting plant growth and ecosystem functioning. By understanding the carbon content and characteristics of roadside grassland soil, we can evaluate its fertility and potential for supporting vegetation. Assessing roadside grassland soil carbon characteristics is important for understanding soil fertility, carbon sequestration potential, and the impact of human activities on soil health. The investigation includes elemental analysis of grassland soil and on that base calculation of ratios, soil organic carbon, soil carbon stocks, the carbon dioxide equivalent emissions from SCS soil carbon stocks loss. The samples have more percentage of element hydrogen which contribute to anaerobic conditions in grassland soil include waterlogging or poor drainage, high organic matter content, and compacted soil. The C/N (Carbon to Nitrogen) ratio is low and this is the reason of delayed decomposition and difficulties of nutrient cycling processes within the ecosystem. The soil organic carbon varies between 1 % and 2 %. Soil carbon stock between 304gC and 474 gC may be considered relatively low. The carbon dioxide equivalent emissions from SCS soil carbon stocks loss was between 2 and 3 %. This loss in carbon dioxide equivalent emissions from soil carbon stocks can be considered relatively low and potentially beneficial. Implementing practices that promote carbon sequestration, such as reducing soil disturbance, implementing cover cropping, and adopting sustainable land management practices, can help mitigate soil carbon loss and reduce emissions.

Soil disturbance induced by shield tunnelling in sensitive clay: In situ test and analyses

Shield tunnelling in sensitive soil causes disturbance to the surrounding soil, damages the soil structure, and results in soil strength reduction. It has a significant impact on the strength and deformation of the soil during shield tunnelling, and further affects the long-term post-construction settlement of the tunnel structure. This paper firstly obtained the soil disturbance and its distribution especially under the tunnel by the in-situ measurement, and the effect of tunneling advancing speed on soil disturbance degree was analyzed. In this paper, in situ tests were performed on an earth pressure balanced (EPB) shield tunnelling site of a subway in deep soft soil layers in Ningbo. Before and after the shield tunnelling, the cone penetration tests (CPTs) were carried out along the axis and profile of the tunnel, and the cross-hole shear wave velocity tests were conducted. Displacement of the surrounding soil and excess pore water pressure (EPWP) were also monitored during shield tunnelling. The results showed that after shield tunnelling the cone penetration resistance (CPR) and shear wave velocity of the surrounding soil decreased remarkably, further confirming that shield tunnelling caused disturbance to the sensitive soft soil. The soil disturbance degree (SDD) is defined based on the CPR, and the soil disturbance boundary caused by shield tunnelling is determined based on distributions of SDD and EPWP. Horizontally, the disturbance boundary of the surrounding soil is located about 0.8D (D represents the tunnel diameter) outside the tunnel, and vertically, the bottom and top of the disturbance boundary are located about 1.29D below and 0.58D above the tunnel. The maximum SDD at the bottom and top of the tunnel reached 80% and 90% respectively, and the average SDD of the disturbance range below the tunnel is about 60%. The testing results indicated that a higher advancing speed causes a greater disturbance to the surrounding soil, and all the analysis results provide helpful guidance for optimizing the EPB shield tunnelling and reducing soil disturbance.

Perceptions and sociocultural factors underlying adoption of conservation agriculture in the Mediterranean

The Mediterranean region is facing major challenges for soil conservation and sustainable agriculture. Conservation agriculture (CA), including reduced soil disturbance, can help conserve soils and improve soil fertility, but its adoption in the Mediterranean region is limited. Examining farmers’ perceptions of soil and underlying sociocultural factors can help shed light on adoption of soil management practices. In this paper, we conducted a survey with 590 farmers across Morocco, Spain and Tunisia to explore concepts that are cognitively associated with soil and perceptions of tillage. We also evaluated differences in perceptions of innovation, community, adaptive capacity, and responsibility for soil. We found that farmers’ cognitive associations with soil show awareness of soil as a living resource, go beyond agriculture and livelihoods to reveal cultural ties, and link to multiple levels of human needs. Beliefs about the benefits of tillage for water availability and yield persist among the surveyed farmers. We found that openness towards innovation, perceived adaptive capacity and responsibility for soil were associated with minimum tillage, whereas community integration was not. Education, age and farm lifestyle were also associated with differences in these perceptions. CA promotion in the Mediterranean should emphasize the multiple values of soil, should demonstrate how sufficient yields may be achieved alongside resilience to drought, and be tailored to differing levels of environmental awareness and economic needs across north and south.

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.

Sustainable soil management in the United Kingdom: A survey of current practices and how they relate to the principles of regenerative agriculture

AbstractSustainable soil management is essential to prevent agricultural soil degradation and maintain food production and core soil‐based ecosystem services. Regenerative agriculture, one approach to sustainable soil management, is rapidly gaining traction in UK farming and policy. However, it is unclear what farmers themselves consider to be sustainable soil management practices, and how these relate to the principles of regenerative agriculture. Further, there is little insight into how sustainable soil management is currently promoted in agricultural knowledge and innovation services (AKIS). To address these knowledge gaps, we undertook the first national‐scale survey of sustainable soil management practices in the United Kingdom and complemented it with targeted interviews. We found high levels of awareness (>60%) and uptake (>30%) of most sustainable soil management practices among mixed and arable farmers. Importantly, 92% of respondents considered themselves to be practising sustainable soil management. However, our analysis shows that farmers combine practices in different ways. Not all these combinations correspond to the full set of regenerative agriculture principles of reduced soil disturbance, soil cover and crop diversity. To better understand the relationship between existing sustainable soil management practices in the United Kingdom and regenerative agriculture principles, we derive a “regenerative agriculture score” by allocating individual practices among the principles of regenerative agriculture. Farmers who self‐report that they are managing soil sustainably tend to score more highly across all five principles. We further find that sustainable soil management messaging is fragmented and that few AKIS networks have sustainable soil management as their primary concern. Overall, our study finds that there are multiple understandings of sustainable soil management among UK farmers and land managers and that they do not correspond to regenerative agriculture principles in a straightforward way. This diversity and variety in sustainable soil management needs to be taken into account in future policy and research.

Effects of Utilization Methods on C, N, P Rate and Enzyme Activity of Artificial Grassland in Karst Desertification Area

To investigate the effects of different utilization methods on the ratio characteristics of soil C, N, P and enzyme activities of grassland soil is of great significance for the sustainable utilization of grassland. In this study, the effects of different utilization methods on soil C, N, P rate and enzyme activities were investigated in artificial grasslands treated with grazing grassland (GG), mowing grassland (MG) and enclosed grassland (EG). The results showed that: (1) the contents of soil organic carbon (SOC), total phosphorus (TP) and ammonium nitrogen (NH4+-N) were EG > GG > MG; the contents of total nitrogen (TN), alkaline nitrogen (AN) and nitrate nitrogen (NO3−-N) were GG > EG > MG; the contents of available phosphorus (AP) and C:N were EG > MG > GG; the contents of C:P and N:P were MG > GG > EG; (2) β-1,4-Glucosidase (βG) and β-1,4-N-Acetylglucos-Aminidase (NAG) activities were GG > EG > MG, acid phosphatase (ACP) was EG > MG > GG, Leucine Aminopeptidase (LAP) was MG > EG > GG, C:NEEA and C:PEEA were GG > EG > MG, N:PEEA was GG > MG > EG; (3) redundancy analysis showed that AN (F = 4.90, p = 0.01) was an important driver of soil enzymes. We concluded that there were significant differences in soil C, N, P, enzyme activity and their ratio characteristics under different grassland uses. EG is closer to the standard ratio of global soil ecosystems. Therefore, reducing soil disturbance and optimizing fertilization are effective ways to improve soil enzyme activity and maintain good soil nutrient circulation.

Induced Deformation and Protection of a Hybrid Timber–Masonry Historical Structure from Adjacent Metro Tunneling

The construction of the tunnels of Metro Line 4 and Gulou Station in central Nanjing poses a potential threat to the nearby historic building, Gulou Tower, due to the relatively small spacing and the deteriorated structure behaviors. Two aspects are important for the protection of Gulou Tower: (i) reducing the soil movement caused by the tunnel–station construction and (ii) increasing the total stiffness of this sensitive building. This research first presents the main features of two tunnels and the triple-arch tunnel as the connection between the two tunnels and Gulou Station. The details of the excavation means and construction procedures of the tunnels, together with the engineering measures that tend to reduce soil disturbance during tunnel excavation, are presented. Meanwhile, to improve the overall stiffness of Gulou Tower, additional support for the masonry terrace and the upper timber structure is also discussed. Moreover, the construction procedures of the tunnels and the station that could influence the settlement development of Gulou Tower are also suggested. The measured ground settlement and structure displacement are found to be limited to the allowable values, indicating that the aforementioned protective measures are adequate to protect hybrid timber–masonry historical structures nearby tunneling.

Mechanisms of conservation tillage on nitrogen-fertilizer reduction and maize grain improvement in Mollisols of Northeast China: Insights from a 15N tracing study.

Conservation tillage is an important management practice to guarantee soil fertility in degraded Mollisols. It is still unclear, however, whether the improvement and stability of crop yield under conservation tillage can be sustainable with increasing soil fertility and reducing fertilizer-N application. Based on a long-term tillage experiment initiated in Lishu Conservation Tillage Research and Development Station by Chinese Academy of Sciences, we conducted a 15N tracing field micro-plot experiment to investigate the effects of reducing nitrogen application on maize yield and fertilizer-N transformation under long-term conservation tillage agroecosystem. There were four treatments, including conventional ridge tillage (RT), no-tillage with 0% (NT0), 100% (NTS) maize straw mul-ching, and 20% reduced fertilizer-N plus 100% maize stover mulching (RNTS). The results showed that after a complete cultivation round, the average percentages of fertilizer N recovery in soil residues, crop usage, and gaseous loss were 34%, 50%, and 16%, respectively. Compared with conventional ridge tillage, no-tillage with maize straw mulching (NTS and RNTS) significantly increased the use efficiency of fertilizer N in current season by 10% to 14%. From the perspective of N sourcing analysis, the average percentage of fertilizer N absorbed by crop parts (including seeds, straws, roots, and cobs) to the total N uptake reached nearly 40%, indicating that soil N pool was the main source of N for crop uptakes. In comparison with conventional ridge tillage, conservation tillage significantly increased total N storage in 0-40 cm by reducing soil disturbance and increasing organic inputs, and thus ensured the expansion and efficiency increment of soil N pool in degraded Mollisols. Compared with conventional ridge tillage, NTS and RNTS treatments significantly increased the maize yield from 2016 to 2018. In all, by improving fertilizer nitrogen utilization efficiency and maintaining the continuous supply of soil nitrogen, long-term management of no-tillage with maize straw mulching could achieve a stable and increasing maize yield in three consecutive growing seasons and simultaneously reduce environmental risks derived by fertilizer-N losses, even under the condition of 20% reduction of fertilizer-N application, and thus actualize the sustainable development of agriculture in Mollisols of Northeast China.

Management Effect on the Weed Control Efficiency in Double Cropping Systems

There are often negative side-effects associated with the traditional (silage) maize cropping system related to the unprotected soil surface. Reducing soil disturbance could enhance system sustainability. Yet, increased weed pressure and decreased nitrogen availability, particularly in organic agriculture, may limit the implementation of alternative management methods. Therefore, a field experiment was conducted at two distinct locations to evaluate the weed control efficiency of 18 organically managed silage maize cropping systems. Examined parameters were relative weed groundcover (GCweed) and its correlation with maize dry matter yield (DMY), relative proportion of dominant weed species (DWS) and their groups by life form (DWSgroup). Treatment factors comprised first crop (FC—winter pea, hairy vetch, and their mixtures with rye, control (sole silage maize cropping system—SCS)), management—incorporating FC use and tillage (double cropping system no-till (DCS NT), double cropping system reduced till (DCS RT), double cropped, mulched system (DCMS Roll) and SCS control), fertilization, mechanical weed control and row width (75 cm and 50 cm). The variation among environments was high, but similar patterns occurred across locations: Generally low GCweed occurred (below 28%) and, therefore, typically no correlation to maize DMY was observed. The number of crops (system), system:management and occasionally management:FC (group) influenced GCweed and DWS(group). Row width had inconsistent and/or marginal effects. Results suggest differences related to the successful inclusion of DCS and DCMS into the rotation, and to the altered soil conditions, additional physical destruction by shallow tillage operations, especially in the early season, which possibly acts through soil thermal and chemical properties, as well as light conditions. DCS RT could successfully reduce GCweed below 5%, whereas DCS NT and particularly DCMS (Mix) suffered from inadequate FC management. Improvements in DCMS may comprise the use of earlier maturing legumes, especially hairy vetch varieties, further reduction/omission of the cereal companion in the mixture and/or more destructive termination of the FC.

A grass–legume cover crop maintains nitrogen inputs and nitrous oxide fluxes from an organic agroecosystem

AbstractLegume cover crops are central to an ecological nutrient management approach that can reduce nitrogen (N) losses from agriculture. Diversifying cropping systems with a legume–grass cover crop mixture could further reduce N losses by increasing soil N assimilation and synchronizing N mineralization with N uptake by the following crop. We established four winter cover crop treatments (crimson clover, cereal rye, clover–rye mixture, and weedy fallow control) in an organic grain agroecosystem that had been managed for 30 years with a legume cover crop as the only external N source. We hypothesized that the legume–grass mixture would provide similar inputs of biologically fixed N2 compared with the sole legume, while reducing N2O emissions during decomposition following tillage. We measured cover crop aboveground biomass C:N and clover N2 fixation, soil inorganic N and N2O fluxes throughout the corn growing season following cover crop tillage, and corn N assimilation at harvest. Even with a reduced clover seeding rate in mixture, the clover and mixture treatments had similar fixed N inputs, litter N and C:N, and no differences in cumulative N2O emissions. During the first peak flux, N2O emissions were 2–5 times higher in clover and mixture relative to rye and fallow, with no differences between clover and mixture. There were no treatment differences at the second N2O peak, which followed the first major rain event. We contextualized these findings by calculating a 6‐year partial N mass balance for this agroecosystem, which was slightly negative (−6.8 ± 0.8 kg N ha−1 year−1) when accounting for historical mean annual N2O emissions and nitrate leaching. Overall, N inputs and harvested N exports were approximately in balance for this legume‐based crop rotation, suggesting that the legacy of ecological nutrient management has promoted efficient N cycling. However, results from our field experiment indicate that short‐term N2O flux rates following cover crop incorporation can be high even for a legume–grass mixture. Additional strategies to reduce soil disturbance are therefore needed to further tighten N cycling in organic grain agroecosystems.