Soil System Research Articles

Impact of leguminous crop residues on rice performance in diverse cropping systems in the alluvial soils of eastern Uttar Pradesh

In eastern Uttar Pradesh, the traditional rice-wheat cropping sequence has been identified as a factor contributing to unsustainable agricultural practices, resulting in low productivity and returns for small and marginal farmers. Crop diversification presents a viable solution to enhance productivity and ensure food and nutritional security for these farmers. A field experiment conducted under the All India Coordinated Research Project (AICRP) on Integrated Farming Systems (IFS) at Acharya Narendra Deva University of Agriculture and Technology, Ayodhya, U.P., India, from 2019-20 to 2021-22, evaluated the growth, yield attributes, and production potential of rice under ten rice-based cropping systems under irrigated medium-land conditions. The systems assessed included rice-wheat-fallow, rice-wheat-greengram, rice-frenchbean-greengram, rice-gram-cowpea, rice-mustard-greengram, rice-linseed-blackgram, rice-berseem-sudanchari, rice-oat-maize + cowpea, rice-cauliflower-okra, and rice-potato-cowpea (vegetable). The legume-based systems significantly enhanced plant height, which was attributed to the higher nitrogen availability from the decomposition of legume residues. Legume-based systems showed an increase in the number of leaves per hill and LAI, reflecting improved vegetative growth. Effective tiller production was higher in these systems, which contributed to superior panicle length, grain count, and grain weight. Among these systems, rice-frenchbean-greengram and rice-gram-greengram consistently outperformed the conventional system in terms of yield attributes and the yield of grain and straw. The integration of legume crops into rice-based sequences can improve soil fertility, promote better vegetative growth, and enhance yield, thereby contributing to more sustainable and productive rice cultivation.

Kinetics of Non-exchangeable Potassium Release in Rice-groundnut Cropping System under Alluvial Soils of Odisha, India

Non exchangeable K release can very much influence soil K fertility. The experiment was carried out to investigate the amount of non-exchangeable potassium released from Inceptisols with rice-groundnut cropping system and to use various kinetic equations to describe the release. Release rates of non-exchangeable potassium were determined for five different soils collected from rice-groundnut cropping system fertilized @ 0 and 40 kg K ha-1 over three years. The non-exch K release rate was studied by successive extraction with 0.01M CaCl2 methods. The results show that the proportion of exch.K and non-exch.K to total K varied between 2.76 to 4.95% and 8.39 to 9.95%, respectively. Per cent of clay or silt+clay correlated significantly with water soluble, exch. and non-exch. K. Five mathematical models (elovich equation, power function, parabolic diffusion, first and zero order equation) were used to describe cumulative K release pattern. The elovich and parabolic equation described the K release kinetics satisfactory as evidenced by the highest correlation coefficients and lowest values of standard error of estimates (SEE). The release of Step-K and CR-K was higher in state recommend dose (SRD) than K control which concluded that the SRD of K (40 kgha-1) is adequate to sustain the productivity of intensive rice-ground nut cropping system in alluvial soils of Odisha.

A Review of Studies on the Effects of Anthropogenic Disturbances on Plant–Soil–Microorganism Interactions in Grassland Ecosystems: Based on Grazing and Tourism Perspectives

As the most widely distributed and largest terrestrial ecosystem in the world, grasslands play an important role in supporting global livestock production and maintaining ecosystem services. In light of the accelerated global socio-economic development and sustained population growth, grassland ecosystems are increasingly subjected to anthropogenic disturbances. However, there is a paucity of research examining the impact of such disturbances on plant–soil–microorganism interactions in grassland systems, particularly from the perspectives of grazing and tourism. Accordingly, this study presents a comprehensive analysis of the impacts of anthropogenic disturbance on grassland ecosystems over the past two decades, employing a dual perspective of grazing and tourism and utilizing econometric analysis of the existing literature through software such as CiteSpace. The results of this study demonstrate the following: (1) The current research focus is primarily concentrated in the fields of ecology and environmental sciences, particularly on the topics of plant diversity, abundance, and diversity, as well as the intensity of grazing. These areas may represent key development direction of future research. (2) The impact of anthropogenic disturbances on grassland ecosystems is primarily associated with grazing activities. Moderate grazing disturbances can facilitate the healthy development of grassland ecosystems. However, the intermediate disturbance hypothesis (IDH) may not fully account for the effects of grazing intensity on grassland ecology. At present, there is still a paucity of systematic research to determine the ecological indicators of grassland under a dual-disturbance scenario. It is recommended that future research be carried out to investigate the compound effects of trampling by tourism activities on plant–soil–microorganism interactions in grassland ecosystems. (3) The mutual feedback mechanism may represent a potential mechanism by which anthropogenic disturbances affect the coupled relationship between the plant, soil, and microbial systems in grassland ecosystems. Furthermore, the interaction among these three systems has the potential to exert direct or indirect impacts on the structure and function of grassland ecosystems in the context of disturbances. The present study aims to provide an overview of the structure and function of grassland ecosystems under anthropogenic disturbances. The objective is to identify a balance between the rational use of grassland and ecological protection under anthropogenic disturbance and to provide scientific reference for the sustainable use of grassland worldwide.

A new grouting procedure to enhance axial response of helical piles in sand

Helical (or screw) piles are deep foundation elements consisting of a steel shaft with single or multiple helical plates (helices) attached near the base of the shaft. The helices and shaft are rotated into the ground using a torque motor located at the head of the shaft. The axial resistance of the piles is provided through bearing on the helices with some additional axial resistance derived from skin friction on the shaft. This paper examines the benefits of a variation of this foundation system in sandy soils, which involved post-installation injection of a cementitious grout in the vicinity of the helix. The intent is that the grout adds a bond strength to a volume of sand that has a larger diameter than that of the helix, thereby increasing the bearing resistance. A new set-up devised to facilitate easy and rapid grouting to take place is first described. The benefits of grouting are then examined in a series of full-scale static tension and compression tests performed at sand sites in Perth, Australia involving both grouted and un-grouted single helix piles. It is demonstrated that grouting led to doubling of axial stiffness and capacity with the addition of just 80 litres of grout to a 350mm diameter helix. The increases observed are quantifiable by combining a recently published design method with measured injected grout volumes.

Tolerance of Xanthomonas campestris for heavy metals typically associated with brownfield land

Heavy metals as environmental contaminants often exhibit high latency and persistence in soil systems. The capacity of Xanthomonas campestris to tolerate 1mM – 15mM concentrations of lead, cadmium and chromium(VI) which are typically associated with soil pollution due to industrial activities was assessed in this study. Bacterial abundance and enzymatic activity were seen to decrease with increasing heavy metal concentration and contact time. Cadmium was the strongest inhibitor of growth while chromium(VI) was identified as the most toxic to X. campestris with regards to enzyme activity. The viable bacterial counts of Xanthomonas campestris after exposure to the heavy metals dropped from 0.97 – 1.03 Log CFU/mL on day 0 to mean values ranging from 5.92 – 0.00 Log CFU/mL on day 7 of the study at the different concentrations applied representing reductions of 26.49% – 100%, 33.76% – 100% and 33.38% – 100% for Pb, Cd and Cr(VI) respectively. The changes in growth differed significantly (p≤0.05) between groups from one heavy metal to the other and within groups from one heavy metal concentration to the other. Pb, Cd and Cr(VI) all inhibited oxidase, catalase and protease activity at higher concentrations. Only Cd exerted an inhibitory effect against α-amylase activity but only at 10 mM and 15 mM concentrations after 5 – 7 days exposure. Pb and Cr(VI) only exhibited inhibition against cellulase activity by the end of the study at the highest concentration of 15 mM. The study established that acute exposure to the heavy metals, lead, cadmium and chromium (VI) had potential to inhibit growth and certain enzymatic activities in X. campestris.

Karrikins biosynthesis, signaling route, regulatory roles, and hormonal crosstalk in plant soil system

Karrikins biosynthesis, signaling route, regulatory roles, and hormonal crosstalk in plant soil system

Effect of polyethylene microplastics on soil organic carbon pool dynamics in the soil-rhizosphere-alfalfa system

The effect of microplastics (MPs) on soil organic carbon (SOC) has become a growing concern. However, most studies have focused on the effect in a single soil system, and little is known about how MPs affect the soil carbon pool in the soil-plant system. In this study, a 90-day pot experiment was conducted with different concentrations (0%, 0.5%, 1%, and 5% w/w) and exposure times (30d, 60d, and 90d) of polyethylene microplastics to investigate their effects on SOC pools. The results showed that MPs increased particulate organic carbon (POC) and mineral-associated organic carbon (MAOC) pools, while decreasing microbial biomass carbon (MBC). Initially, MPs increased POC by disguise and their effects on enzyme activities and C degradation genes, and indirectly increased MAOC by affecting dissolved organic carbon (DOC) levels (via soil pH) and stimulating enzyme activities. However, as alfalfa rapidly grew from the branching to the flowering stage, plants inputted C into the POC pool via rhizodeposition, while activating and absorbing the MAOC pool for growth through roots, resulting in an increase in POC and a decrease in MAOC. Moreover, plants had priming effects on soil MBC, enzyme activities, and C degradation genes, further influencing SOC pools. Overall, MPs affected plant growth and soil carbon pools by altering soil properties, while plants in turn influenced soil organic carbon pools and the impact of MPs on soil properties. This study provides deeper insights into the effect of MPs on SOC dynamics in the soil-rhizosphere-plant system.

Variability of functional and biodiversity responses to perturbations is predictable and informative

Perturbations such as climate change, invasive species and pollution, impact the functioning and diversity of ecosystems. However diversity has many meanings, and ecosystems provide a plethora of functions. Thus, on top of the various perturbations that global change represents, there are also many ways to measure a perturbation’s ecological impact. This leads to an overwhelming response variability, which undermines hopes of prediction. Here, we show that this variability can instead provide insights into hidden features of functions and of species responses to perturbations. By analysing a dataset of global change experiments in microbial soil systems we first show that the variability of functional and diversity responses to perturbations is not random; functions that are mechanistically similar tend to respond coherently. Furthermore, diversity metrics and broad functions (e.g. total biomass) systematically respond in opposite ways. We then formalise these observations to demonstrate, using geometrical arguments, simulations, and a theory-driven analysis of the empirical data, that the response variability of ecosystems is not only predictable, but can also be used to access useful information about species contributions to functions and population-level responses to perturbations. Our research offers a powerful framework for understanding the complexity of ecological responses to global change.

Response of offshore large-diameter pipe piles in layered poroelastic soil to lateral dynamic loading

The analytical solution for the lateral dynamic response of offshore large-diameter pipe piles embedded in seawater and layered saturated seabed soil is proposed. The hydrodynamic pressures of the outer and inner seawater are derived based on the inviscid compressible assumption of fluid, and the dynamic soil resistances of the outer and inner layered saturated seabed soil are derived based on Biot's poroelastic theory. The analytical expressions of the lateral dynamic response of the pile are obtained by using the transfer matrix method, and the dynamic characteristics of the lateral response of offshore pipe piles are parametrically investigated. It is concluded from the analysis results that the outer and inner hydrodynamic pressures significantly affect the natural frequency of the pile–water–soil system. Additionally, employing a homogeneous soil model with the same average modulus to represent the layered seabed soil can lead to significantly inaccurate estimations of the natural frequency and pile-head displacement of offshore pipe piles.

Analysis of the effect of the heat stabilizer outer surface finning on soil cooling efficiency

Relevance. The construction of buildings and structures in permafrost conditions is associated with the problem of soil thawing. To prevent this phenomenon, heat stabilizer have proven themselves good in practice. Their successful use is difficult without preliminary modeling of heat flows in the soil–heat stabilizer system. The most effective design of a passive heat stabilizer is an installation with two-phase of refrigerant. An additional increase in the efficiency of using a two-phase heat stabilizer is possible due to the finning of the outer surface of the outer pipe of it. Aim. To calculate the efficiency of using a heat stabilizer with and without finning of the outer surface. Objects. Heat stabilizer, refrigerant, heat transfer, frozen soil. Methods. The mathematical model for describing the processes of heat and mass transfer in the heat stabilizer–frozen soil system is considered in an axisymmetric formulation. There are three subtasks: the movement of liquid refrigerant in the inner tube of the heat stabilizer, the two-phase convective flow of refrigerant in the gap between the inner and outer tubes and conductive heat exchange in the system of the heat stabilizer–frozen soil. The influence of the finning of the outer surface of the heat stabilizer is considered within the framework of the modified concept of the skin factor. Results and conclusions. The authors have obtained the pressure and temperature distributions along the length of the heat stabilizer. It was found that the presence of fins on the outer surface of the external pipe of the heat stabilizer increases the heat flow from the soil by 10%. It is determined that the soil is effectively cooled within 1 m from the heat stabilizer; this distance is recommended as optimal for the placement of an adjacent heat stabilizer.

Mercury methylation and bioaccumulation in purple paddy soil systems with different acid-base properties

Paddy soil is recognized as a hotspot for mercury (Hg) transformation. Soil acid-base property (expressed as pH) plays a crucial role in Hg methylation and accumulation in paddy systems. However, it is challenging to study this process in soils with varying pH values due to the rarity of a single soil type spanning a wide pH range. Purple paddy soil, vital for rice cultivation in southwestern China, occurs naturally in three types based on pH: acidic, neutral, and calcareous. This variation makes purple paddy soil an ideal subject for these studies. Thus, this study investigated Hg transformation and bioaccumulation across these three purple soil types. The results showed that during the rice growing seasons, both methylmercury (MeHg) concentration and methylation potential were higher in acidic purple paddy soil than in neutral and calcareous types. In addition, total mercury (THg) and MeHg concentrations in plant tissues grown in acidic purple paddy soil were significantly higher than in other two purple soil types. These results suggest that acidic purple paddy soil was conducive to Hg methylation and accumulation in rice plants. Given that soil acidification is becoming a serious global issue, the findings could offer fundamental data on the potential risk of Hg exposure due to soil acidification.

Politics of Economic Rents and Petroleum Resources Taxation in Oil and Gas Industry

This paper argues the politics of economic rents and petroleum resources taxation in oil and gas industry. It does this through the understanding concept of economic rent, royalties, corporation tax, resource rent tax and brown tax. It surveys the comparative merits and demerits of royalties, corporation tax, resource rent tax and brown tax. The paper discusses the concept of tax structure and proposes that it should be progressive and fair to both government and investors. The principles of a good tax structure should include simplicity, convenience, ability to pay, economical, equity and certainty. While the characteristics of a good tax structure should include proportionality, it should ensure fairness and acceptability by both the government and the citizens together with foreign investors. This way, it enhances the longevity of that particular tax system and rewards will be very high. Although taxation is mandatory to all income earners and profits gainers, there are key economic considerations in designing a tax structure for new petroleum producing countries. The paper argues these economic considerations to include ownership of petroleum resources, good investments laws, strong, accountable and transparent economic institutions, good fiscal and monetary policies, land ownership, strong private banking industry, market driven insurance policies, market for consumption of petroleum products, dynamic and friendly technology, strong regulatory environment and affordable trained workforce. As the taxation is implemented, the concept of source and residence taxation become very handy and the paper argues that source of the income and residence of the investor should be taken into the consideration from the onset of the designing of tax system and particularly in oil and gas industry. While the source of income may be in the country and residence outside the country, the tax system should carefully consider this so that the investor and the tax agency (the government) consent and each party plays it role conveniently. Although advantages and disadvantages of source tax and residence tax stand, the main rules in determining sources of investment income remains of source rules. The paper notes interest-based politics has let to unsuccessful implementation of tax system in oil and gas industry. While the paper reviews copies of empirical literature, it uses comparative method and process-tracing in understanding politics of economic rents and petroleum resources taxation in oil and gas industry. It concludes that incremental sliding scale taxation is appropriate in oil and gas industry and politics of greed affects the tax regime implementation in petroleum industry. Keywords: politics, economic, rents, petroleum, resource, taxation, structure, oil, gas, industry

Microplastics' impact on soil health and quality: Effect of incubation time and soil properties in soil fertility and pollution extent under the circular economy concept.

The aim of the present study is to highlight the effect of two commonly used plastics, polyethylene (PE) and polyethylene terephthalate (PET), on the quality and health indices of soil. To this end, a pot experiment was carried out using two soils, one acidic and one alkaline. The soil samples were collected from rural areas of central and Northern Greece and had similar particle size composition and almost equal copper (Cu), zinc (Zn), cadmium (Cd) and lead (Pb) concentrations. PE and PET microplastics (MPs) were added into the soil samples in two ratios (2% and 4% v/v) and remained in the soils for 20, 60 and 120 days. Then, the changes in the properties, nutrients, potentially toxic elements and health indicators of the soil samples were measured. PE addition at 4% v/v caused the maximum increase in trace element availability when it remained in the soil sample for 120 days. In contrast, PET addition caused a maximum decrease in the DTPA-extractable concentration of toxic elements (Cd and Pb), after 120 days of incubation in acid and alkaline soil. The present work provides a fresh perspective evaluating MPs from unwanted waste to materials with potential positive benefits, enhancing the circular economy approach to soil systems. Knowledge of the MPs present in soils, along with physicochemical soil properties, including their nutrient and toxic element content, are critical aspects that need to be addressed to ensure that soil quality and health are not adversely affected.

Investigation of the effects of mainshock-aftershock sequences on the dynamic responses of pipeline considering soil-pipeline interaction

Pipelines are important structural elements that are frequently used today to meet many infrastructures needs such as drainage, natural gas or water transmission. In this context, the usability of such structures, which are important elements of infrastructure systems, especially after disasters such as earthquakes, is of great importance. For this reason, within the scope of this study, a parametric investigation of the seismic behaviors of a natural gas pipeline system under mainshock-aftershock sequences have been carried out, specifically taking into account the soil-natural gas pipeline interaction (SNGPI) in the help of finite element model (FEM) proposed. Before developing the model of SNGPI system proposed using solid element, the fundamental mode frequencies of the pipeline system modeled using the solid element for the verification have been compared with those of obtained from the pipeline system modeled using the beam element and the analytical solutions. After verification of proposed model is demonstrated, SNGPI system has been modeled and its fundamental modes have been compared with mode frequencies of soil stratum obtained from well-known simple analytic solutions. After this stage, the dynamic analyses of natural gas pipeline (NGP) system in the time domain have been carried out using four different soil systems and four different mainshock-aftershock sequences. The results of the nonlinear time-history analyses have been investigated in terms of the stress and the displacement responses. Parametric evaluations show that the greatest displacements and the stresses occurring at the considered nodes of NGP system may be importantly affected from mainshock-aftershock sequences and soil stiffness changes. As the soil stiffness decreases, both the peak stresses and displacements increased significantly. On the other hand, the same responses obtained under mainshock loadings, which have relatively lower peak ground acceleration (PGA)/peak ground velocity (PGV) ratio compared to aftershock loadings, are generally larger than those obtained under aftershock loadings.

Three-dimensional fully coupled analytical solution for a water-pile-saturated soil system under vertical P-wave incident

Water-pile-soil interaction and the three-dimensional scattered wave effect play crucial roles in the seismic response of structures built on saturated seabed subjected to vertical P-wave incidents. This study proposes a fully coupled three-dimensional continuum model of water-pile-saturated media to investigate the seismic response of the system under vertical seismic excitation. By employing Helmholtz decomposition and the method of variable separation, the governing equations are decoupled based on assumed boundary and interface conditions, yielding the solution equation in the frequency domain. The effects of various pile and soil parameters on the seismic response are analyzed from multiple perspectives, along with the impact on the spatial distribution of three-dimensional scattered wave effects. Results indicate that the seismic response of piles and saturated soil is significantly influenced by the presence of water and the three-dimensional scattered wave effect.

Investigation of a Multiflow Ejector Equipped with Variable-Length Links for Thrust Vector Control Using Euler’s Methodology

The coordinated operation of multiple jet devices enhances the efficiency of technological processes and thrust vector control systems, enabling the resolution of various practical challenges. Traditional jet control systems regulate the thrust vector in the direction from +20° to −20° in a 3D space. For the first time, this study considers, from a general perspective, the conditions under which the thrust vector angle can vary from +180° to −180° in any direction within a complete geometric sphere, including thrust reversal. Conceptual design using computational fluid dynamics (CFD) techniques considers kinematic schemes with variable lengths and flexible links. This study demonstrates the technical feasibility of controlled energy distribution through multidirectional ejector channels, including the maintenance of constant pressure at the nozzle apparatus inlet. Potential modernization strategies for the Laval nozzle incorporating a rotary diffuser were examined. The research outcomes are patented and aimed at developing a digital twin of the jet system for training artificial intelligence based on the philosophy of science and technology and Euler’s methodology within interdisciplinary works. The findings are primarily applicable to research and development efforts focused on creating energy-efficient oil and gas production systems. Furthermore, the research results can be applied to the development of advanced maneuverable unmanned vehicles and robotics for various purposes.

Disentangling mechanisms by which microplastic films affect plant-soil systems: physical effects of particles can override toxic effects of additives

BackgroundMicroplastics, polymer-based particles < 5 mm, affect plant–soil systems positively or negatively, suggesting there are different modes of action. Microplastics, as particles, have physical effects but the leaching of additives likely contributes chemical mechanisms, both of which may be dependent on microplastic size. To disentangle such mechanisms, we established a controlled experiment involving polypropylene and polyethylene films of small, medium and large size, and we evaluated the individual and combined effect of plastic particles and additives (leachates from plastic particles) on soil properties and plant performance of the phytometer Daucus carota and on bare soils.ResultsWe find that additives better explained variation in soil properties (e.g., 44.6% vs 1.3%). Soil respiration and aggregation were negatively affected for additives, likely due to the presence of toxic substances. Overall, such effects increased as plastic size decreased. By contrast, plastic particles better explained plant biomass responses. The positive effect of particles on aeration which may promote root penetration and nutrient uptake, and microplastics itself as a source of carbon potentially promoting soil microbial activity, help explain the positive effect of particles on plant biomass. Plants mitigated the negative effects of additives on bare soils while enhancing the positive effects of particles. This improvement was likely linked to an increase in root activity and rhizodeposition, as plastic particles improved soil aeration. The combined effect of additives and particles, which mimics the microplastic found in the soil, mitigated their individual negative effects on plant–soil systems. As the negative effect of additives could have been masked by the positive effects of particles, simply reporting net positive effects would capture only part of the response.ConclusionsAdditives and plastic particles differently affect soil properties and plant biomass. Additives primarily negatively affect soil properties due to toxic substances, while plastic particles enhance plant biomass likely by improving soil aeration. When examining microplastics effects on terrestrial systems (i.e., the combined effect of additives and particles), the negative effect of additives may be masked by the positive effects of plastic particles. Reporting only net positive effects risks overlooking these underlying negative effects. Plants can mitigate the negative impacts of additives and amplify the positive effects of plastic particles. Our study emphasizes the importance of investigating both the individual and combined effects of additives and particles to fully understand and address the impacts of microplastics on terrestrial ecosystems.

Effects of salt crystallization on electric field-induced asphaltene desorption at brine–oil interface: Insights from molecular dynamics simulations

Water-in-oil or oil-in-water emulsions, typically stabilized by indigenous surface-active components, are ubiquitous in many natural and industrial settings. In petroleum engineering, these emulsions are highly undesirable owing to their adverse effects on water–oil separation, transportation, quality of the oil products, etc. The application of an external electric field has demonstrated its potential as a promising method for demulsification, especially considering its advantages of energy efficiency and environmental compatibility. The demulsification ability of an electric field arises from the desorption of surface-active species (e.g., asphaltenes in petroleum) from the water–oil interface, which reduces the rigidity of the interfacial film and facilitates the coalescence of the emulsion droplets. The natural presence of salt ions in the water phase, however, can impact electric field induced demulsification process, and this potential influence is studied in this work by molecular dynamics simulations. We report an interesting phenomenon where the presence of NaCl in the water phase can hinder the ability of an electric field to desorb asphaltenes from a brine–oil interface. In particular, NaCl ions exhibit a higher probability of crystallization in bulk brine as the electric field increases, and this crystallization releases free water to the brine–oil interface which hampers the desorption of a model asphaltene. In contrast, CaCl2 lacks the tendency to crystallize, and as the electric field strengthens a continued increase is observed in the desorption of the model asphaltene. Therefore, demulsification by electric field is potentially more effective for brine–oil systems containing CaCl2 than those containing NaCl. This work highlights the interplay between salt ions and electric field, and how it influences interfacial behaviors of surface-active molecules. The findings could benefit the design and optimization of demulsification technologies in industries such as wastewater management, petroleum processing and other chemical treatments.

Nitrifying and denitrifying microbes exhibit distinct community structure and activity responses to different crop rotation systems in subtropical paddy soils

The adverse impacts of double-season rice cultivation on soil health and crop yield can be alleviated by crop rotation. However, the mechanisms by which biotic and abiotic factors influence microbial nitrogen cycling under different crop rotation systems remain unclear. Here, we evaluated the impact of crop rotation in paddy soils on the community abundance, composition, and activity of nitrifying microbes (ammonia-oxidizing archaea and bacteria (AOA and AOB)) and denitrifying microbes (nirK- and nirS-denitrifiers). A 6-year field experiment was performed with four crop rotation systems: (1) double rice as a control, (2) middle-season rice–fallow rotation (MR), (3) middle-season rice–oilseed rape rotation (MROR), and (4) middle-season rice–pak choi–oilseed rape rotation (MRPOR). AOB abundance increased significantly in MROR and MRPOR treatments, whereas AOA abundance decreased significantly in MROR. nirS gene abundance was significantly lower in MROR and MRPOR treatments, whereas nirK gene abundance was significantly lower in MR and MRPOR treatments. AOB and nirK gene community structures were significantly altered by crop rotation; this relationship was closely correlated with soil water content and NO3−-N concentration. For MROR and MRPOR treatments, potential nitrification activity was significantly increased and positively correlated with AOB abundance, whereas denitrification enzyme activity was significantly decreased and correlated with nirK and nirS community structure. Therefore, nitrifiers and denitrifiers exhibit distinct responses to crop rotation in paddy soils, which may influence microbial nitrogen cycling. These findings have practical implications for selecting appropriate cropping regimes.

The Use of Nanotechnology in Improving Irrigation Efficiency

Nanotechnology is becoming a major force in agriculture, especially when it comes to making watering more efficient. This essay looks into how nanomaterials and nanotechnology can be used to improve the way water is used in irrigation systems. This could help solve the serious problems of water shortage and low crop yields. With 9.7 billion people expected to live on Earth by 2050, there has never been a bigger need for efficient farming methods. A lot of water is lost through evaporation, deep percolation, and flow when people use traditional ways to water their plants. Nanotechnology can help with these problems in new and creative ways. One interesting use is making nanoparticles that can be mixed into soil or irrigation systems to help water stay in the soil longer and evaporate less quickly. Nanoparticles can improve the structure and ventilation of soil, which lets more water soak in and less water run off. Nanosensors can also be used to measure the amount of water in the soil in real time. This lets farmers use precise watering to get the best food growth with the least amount of water. These monitors can collect information that can be used to plan watering and automate systems so that water is only used when it's needed. Nanotechnology can also be used to make hydrogels and materials that take a lot of water. This could change the way water is managed in dry areas. These materials can hold a lot of water and slowly give it to plants, so they don't need to be watered as often.