Rainfall Conditions Research Articles

From quarry by-products to a zeolites-based Zn fertilizer with increased resistance to rain leaching

In the face of an extensive literature on the use of zeolites for the removal of metals from water for environmental purposes, it is seldom considered that some metals are also essential nutrients for life and that zeolites could be profitably used to dose their release. Among these, Zn is a key micronutrient, and when its demand by crop is not fully balanced by adequate accessibility, fertilization must be provided using Zn salts that can be, however, easily leached and partly wasted in the environment.In an attempt to solve this critical problem, a new controlled-release formulation of Zn using zeolite-containing geomaterials was designed, prepared, characterized, and tested by applying a sequential, multi-method approach. Different formulations were trialed, and the most effective included 30 wt% pumice by-product and 70 wt% clinoptilolite-rich zeolitized tuff, with about 20 mg/g of exchangeable Zn2+. The enrichment process reached equilibrium after about 8 h, a timing well-tuned with technology transfer. Desorption kinetic tests in a weekly acid environment revealed gradual Zn release, with about 4.28 wt% released after 6 h. When tested as a foliar fertilizer on Vitis vinifera, this formulation demonstrated superior resistance to leaching under simulated rainfall conditions compared to conventional ZnSO4·6H2O fertilizer, maintaining the initial level of Zn (130 mg/kg of dry leaves), while about 22 % of the Zn applied with ZnSO4·6H2O was loss. This outcome was plausibly due to mineral particle adhesion to leaf. Preliminary cost estimates suggest that the product designed here can be placed in the market with competitive sales prices.

Hindcasting long‐term data unveils the influence of a changing climate on small mammal communities

AbstractAimShifting climates are reshaping ecosystems globally and are projected to intensify over the coming century. Understanding how biodiversity will respond to these shifts is crucial for developing effective climate adaptation measures. We generate predictive models built from long‐term data to hindcast historic fluctuations in small mammal abundances as they have responded to shifting rainfall and fire conditions. This data set serves as the basis for predicting historical variations (hindcasting) in small mammal abundances, allowing us to examine their responses to decadal changes in fire and rainfall conditions within our study landscape.LocationAustralia (Victoria).TaxaSmall mammals (Mammalia).Time Period1970–2022.MethodsSmall mammal abundance was surveyed at 36 long‐term trapping sites and modelled against coinciding fire history, vegetation productivity and rainfall using generalized additive mixed models. Six species were then used in predictive modelling against these variables for the decades preceding our monitoring programme (1970–2007).ResultsAll species abundances increased with higher rainfall. Time since fire was also an important variable in all but one species model, with species displaying varying responses to time since fire. Hindcasting predictions for small mammal abundances varied with some species showing marked declines over time. Clear trends emerged, indicating more volatile population fluctuations in response to intensified fire and rainfall extremes in the 21st century. This suggests that periods of higher rainfall and less frequent fire events in the decades preceding our monitoring period supported higher and more stable small mammal abundances.ConclusionsNative species show distinct sensitivity to the combined effects of drought and fire, which has occurred in recent times. Intensification of these drivers has caused increased volatility in small mammal abundances with low abundance extremes occurring more frequently.

Reliability analysis of cutting slopes under rainfall conditions considering copula dependence between shear strengths

Reliability analysis of cutting slopes under rainfall conditions considering copula dependence between shear strengths

Finite Element Method-Peridynamics Coupled Analysis of Slope Stability Affected by Rainfall Erosion

Rainfall is a pivotal factor resulting in the cause of slope instability. The traditional finite element method often fails to converge when dealing with the strongly nonlinear fluid–solid coupling problems, making it impossible to fully analyze the sliding process under the state of slope instability. Therefore, this paper uses the coupling of peridynamics (PD) and the finite element method (FEM) to propose a data exchange mode between the seepage field and the deformation field. The influencing factors of fine particle erosion during rainfall are further considered. According to the damage mechanism of the slope sliding process to the original structure of the soil, a modified erosion constitutive relationship is proposed, which takes into account the destructive effect of plastic deformation on coarse particles. Then, the influence of rainfall duration, rainfall intensity, erosion, and initial saturated permeability coefficient on slope stability was simulated and analyzed. This paper provides a novel concept for slope stability analysis and safety evaluation under rainfall conditions.

Sustainable flood control strategies under extreme rainfall: Allocation of flood drainage rights in the middle and lower reaches of the yellow river based on a new decision-making framework

Climate change has exacerbated the frequency and magnitude of extreme rainfall, which has led to the perpetuation of flooding as a hazard to humans and society. China has begun to consider introducing Flood drainage rights (FDR), a sustainable flood control measure, into non-engineering measures as a complement to engineering measures for flood control. FDR represent the right of regions to discharge regional floodwaters caused by extreme rainfall into the river, and are the primary means of controlling the amount of floodwaters from regions when regional flood capacity is exceeded. However, existing studies on quantitative FDR allocation still have limitations, and some previous methods have resulted in allocation schemes that are not entirely reasonable and fair because they do not comprehensively consider the influencing factors of FDR or the allocation method is unreasonable. This paper explores the impact of flooding on rural and agricultural areas. We incorporate the factors of agricultural economy and security and construct a system of the allocation indicators of FDR composed of five principles: Natural Environmental Endowment, General Economic and Social Development, Agricultural Economy and Security, Macro policy regulation, and Respect for Historical Background. Second, considering the influence of expert judgment and data of different time nodes on the allocation of FDR, we introduce the concepts of expert weight and time weight into the allocation model of FDR, and construct a new set of framework for the allocation of FDR, i.e., "[(expert weight + subjective weight)+(time weight + objective weight)]+decision making model ". To reduce the loss of information during the transformation of subjective judgments, we also introduced triangular fuzzy numbers for the transformation between expert judgments and numbers. Finally, we take the five provinces in the middle and lower reaches of the Yellow River as an example. Using the data from 2010 to 2021, we obtain the final allocation scheme (proportion) of FDR as Henan (33.26%) > Shaanxi (23.08%) > Inner Mongolia (21.31%) > Shanxi (14.44%) > Shandong (7.91%). On this basis, this paper utilizes sensitivity analysis and comparative validation to demonstrate the rationality and effectiveness of the method, and identifies several indicators that have a greater impact on the results of the allocation of FDR. FDR can form part of a set of integrated flood management system together with flood control projects, which greatly alleviates the drainage conflicts arising from flooding caused by extreme precipitation. Under extreme rainfall conditions, FDR improves drainage efficiency and minimizes the overall damage caused by flooding in the watershed. This study can contribute to the sustainable development of the watershed and provide a reference for the promotion and utilization of sustainable flood control measures.

Effects of mixed land use on urban stormwater quality under different rainfall event types

The joint effect of mixed land uses and rainfall event types was studied using a two-year field monitoring program in four urban catchments in Calgary, Alberta, Canada. Event mean concentration (EMC) and event pollutant load (EPL) were employed to evaluate the total suspended sediment (TSS), nitrogen and phosphorus. The correlation analysis showed that most nitrogen and phosphorus components (except for NO2−/NO3− and TDP) predominantly exist in particulate form in the study areas. The correlation for EPL was notably stronger than EMC, which can be attributed to varying rainfall characteristics. The differences in EMCs and EPLs of TSS, nitrogen and phosphorus across catchments indicated that the complexity and spatial distribution of mixed land use can influence the generation and transportation of pollutants in urban runoff. The impacts of rainfall characteristics on stormwater quality are integrated rather than driven by a single rainfall characteristic. Brief but intense events tended to elevate TSS, nitrogen and phosphorus concentrations, especially in complex land-use catchments. Events with long antecedent dry days and short duration also resulted in increased pollutant concentrations, while events with long duration and low intensity could result in higher EPLs. The effect of mixed land use on water quality can vary depending on rainfall event types. Seasonal variations were found in EMC and EPL of TSS, nitrogen and phosphorus, with higher values in the spring and summer than the fall. Seasonal variations are mainly influenced by rainfall conditions, temperature and anthropogenic activities (e.g. lawn fertilization and de-icing with sands). MLR considering rainfall characteristics is an effective method for predicting stormwater quality within a single catchment. Considering complexity and spatial distribution of mixed land use can improve the accuracy of the harmonized MLR model. This research provided insights into understanding the complexities introduced by mixed land use and rainfall event types in urban stormwater quality.

Influence of 3D subsurface flow on slope stability for unsaturated soils

The occurrence of rainfall-induced slope failures has become more frequent due to the effect of climate change. Hence, various studies have been conducted to analyse the effect of rainfall infiltration on slope stability. Physically-based hydrological models have been commonly used with slope stability models such as the infinite slope model to develop slope susceptibility maps. However, a combination of three-dimensional (3D) water balance model with 3D limit equilibrium method (LEM) has not been commonly used. Hence, in this study, a water balance model, GEOtop was used to investigate the influence of subsurface flow in unsaturated soil under extreme rainfall conditions on regional slope stability in 3D directions. The results from the GEOtop model were used as inputs for 3D LEM slope stability analysis performed using the Scoops3D software to obtain the factor of safety (FOS) map for the region. Four slopes within the region were then selected to be modelled in the two-dimensional (2D) seepage and slope stability analyses, SEEP/W and SLOPE/W. Results from the detailed study showed that the pore-water pressures (PWPs) from the 3D water balance analyses were found to be higher than the 2D seepage analyses. Under similar PWP conditions, the FOS from the 2D slope stability analysis was observed to be lower than the 3D analysis for two out of the four slopes. However, the combined 3D water balance and slope stability analyses produced lower FOS compared to the 2D seepage and slope stability analyses due to the higher PWPs in the 3D water balance analyses. Therefore, this study highlights the importance of considering the 3D subsurface flow in unsaturated soil given that it has a significant influence on the FOS of slopes.

Water erosion at different slope lengths

Water erosion is strongly influenced by slope length (Sl), among other factors. The objective of this work was to quantify the water losses (WL) and soil losses (SL) in different Sl, in a Haplic Distrudept. These losses were determined during one year in uncultivated and uncovered soil (BS) and then in soil cultivated in the form of no-tillage (NT) during three cropping cycles, under natural rainfall conditions. The treatments, with one repetition, consisted of the Sl of 11 m, 22 m, 33 m, and 44 m with 8% slope. In the 1st cycle, black oat (Avena strigosa) + forage radish (Raphanus sativus) + common vetch (Vicia sativa) was cultivated, in the 2nd cycle, single black bean (Phaseolus vulgaris) and in the 3rd cycle, single black oat. With the increase of Sl in the interval from 11 to 44 m, the WL and SL increased, and the SL increased with the increase of the WL. WL and SL were explained by Sl in 79% and 99%, respectively, and SL were explained in 76% by WL. The y = a + bx model was fitted to the data (p<0.01). Soil crop for one year in the form of NT reduced WL by 30% and SL by 99% compared to the losses that occurred in the condition in which the soil was under BS. The WL varied less than the SL, in the range from 11 to 44 m of slope.

Analysis of Land Water Balance in Various Rainfall Conditions and Its Utilization to Determine Planting Patterns of Food Crops in the Eastern Part of Seram District of Seram Island

Soil water balance calculation is one of the methods used to estimate the dynamics of soil water content during plant growth. This study aims to describe rainfall conditions and analyze soil water balance as well as determine the growing season and composition of food crop combination patterns based on the available growing season in East Seram Island. This research uses rainfall data for 30 years of observation period 1992-2021 from Geser Meteorological Station (Data analysis with the following stages: (i) rainfall analysis (ii) calculation of average rainfall (iii) determination of rainfall with a 75% chance (iv) calculation of soil water balance using the Thornthwaite and Mather method (v) determination of the growing season and cropping pattern. The results showed that the average rainfall in East Seram was 2,194 mm/year with a water deficit (D) occurring in October and November, then the rainfall had a 75% chance of being exceeded at 1,439 mm/year with a water deficit of 228 mm/year which lasted for eight months, namely August - March. The growing season under normal rainfall conditions was available throughout the year, while under high rainfall conditions, a 75% chance of the growing season was available for five months, namely May and October. The cropping patterns and crop combinations used were monoculture, polyculture, and intercropping with combinations of cassava, maize, sweet potato, groundnut, mung bean, cassava-corn, cassava-peanuts/green beans, maize-peanuts, cassava-corn-peanuts/green beans, cassava-corn-horticultural crops.

A unified runoff generation scheme for applicability across different hydrometeorological zones

Runoff generation in humid and semi-arid regions are usually dominated by saturation-excess mechanism and infiltration-excess mechanism, respectively. However, both mechanisms can co-exist in semi-humid regions. Therefore, we proposed a unified runoff generation scheme to represent the single and mixed runoff generation processes, making it applicable for different hydrometeorological conditions. The saturation-excess runoff generation scheme of the Xin'anjiang model was integrated with a modified Horton infiltration scheme at the grid cell scale. By substituting the original runoff generation scheme of the grid-Xin'anjiang (GXAJ) with the integrated scheme, we developed a new distributed hydrological model called grid-Xin'anjiang-infiltration-excess (GXAJ-IE) model. GXAJ-IE was tested in four watersheds and compared with two benchmark models with single runoff generation mechanism. The results indicate that GXAJ-IE model has higher flexibility and robustness in reproducing flood hydrographs under different rainfall conditions in semi-humid watersheds and has comparable performances with the benchmark models in humid and semi-arid regions.

Application of Microbial-Induced Carbonate Precipitation for Disintegration Control of Granite Residual Soil

Granite residual soil is widely distributed in Southeastern China. Such soils exhibit mechanical characteristics such as loose, rich cracks and easy disintegration, resulting in severe soil erosion disasters under rainfall conditions. Microbial-induced carbonate precipitation (MICP) is a green alternative for soil stabilization. In this study, a new strategy for the disintegration control of granite residual soil using MICP technology is proposed. The effects of the bacterial solution concentration, the cementation solution concentration, and the treatment cycle are investigated through a disintegration test. The optimal treatment parameters for granite residual soil using MICP technology are determined by analyzing the disintegration processes and residual quality indicators of disintegration. The results show that the treated samples have three types of disintegration: complete disintegration, incomplete disintegration, and non-disintegration. The precipitated calcium carbonate (CaCO3) bonds the soil particles and fills the pores. Taking into account the effectiveness and cost and a bacterial solution concentration OD600 = 0.75, five cycles of MICP treatment with a cementation solution concentration of 1.2 mol/L is optimal for the disintegration control of granite residual soil. The cementation-action effects of CaCO3 are verified through scanning electron microscopy (SEM) tests with an energy-dispersive X-ray (EDX) spectroscope. These findings suggest that MICP is a promising candidate to control the disintegration of granite residual soil.

Effect of Lime Source, Fineness and Granulation on Soil Permeation with Contrasting Textures under Simulated Mediterranean Climate Rainfall Conditions

ABSTRACT Granulated micro-fine limes have recently been introduced as liming materials which are purportedly more effective than conventional agricultural limes in terms of rapidly correcting subsoil acidity in no-tillage systems. Hydrated limes are known to react more quickly in soils than calcitic limes, yet their soil permeability has not been evaluated under Mediterranean climate growing conditions. Therefore, the aim of this controlled study was to compare soil permeation and pH neutralization of different liming materials (hydrated lime, calcitic agricultural lime, micro-fine lime and molasses-granulated micro-fine lime) in two contrasting (sand and sandy loam) acid (pHKCl < 4.1) topsoils under simulated Mediterranean climate conditions. Limes were surface applied to 40 cm soil columns and then rainfall (350 mm) was simulated. Subsequently, soil chemical properties (pH, exchangeable cations, available P) were measured in 5 cm increments. Application of all liming materials increased soil pH 1–2 pH units above target pHKCl of 5.5 in the top 5 cm of both soils. Only hydrated lime was able to increase soil pHKCl (5.7–6.8) below 5 cm up to a depth of 15 cm on the sand soil. Hydrated lime, however, resulted in substantial over-liming (pHKCl 7.3–8.7) of the top 5 cm of soil compared to the other materials. Granulated micro-fine lime reacted more slowly than the agricultural limes and is therefore not a suitable quick-fix for subsoil acidity in rain-fed no-till systems under Mediterranean climate rainfall conditions. Whereas hydrated lime showed potential in ameliorating subsoil acidity in the sand soil within one season of rainfall.

The water weakening effect on the progressive slope failure under excavation and rainfall conditions

The water weakening effect refers to the gradual deterioration of soil mechanical properties under long-term saturation. This paper analyzed the impact of water weakening on slope stability under alternating excavation and rainfall. The field investigation speculated shale hydration as the cause of overall slope instability. The mechanical parameters of hydrated shale were determined by the parameter inversion and empirical estimation methods. The simulations were used to restore the process of parameter weakening and slope failure, and confirmed the fact that hydration causes landslide. Furthermore, the failure mechanism of slope and support structure under hydration were investigated. The results show that the mechanical parameters of the slope decreased linearly, whereas the plastic strain–time and total displacement-maximum shear stress curves of the hydrated shale exhibited three stages: slow initial growth, rapid growth in the middle term, and rapid increase in the later period; the rate of slope deformation and the factor of safety reduction also gradually increase over time; under middle stage of hydration, the middle to rear of shale were extruded, while the front first underwent tensile shear deformation, forming a plastic zone of at rear and front excavated slope; In the late stage, hydrated shale quickly reaches its yield limit (maximum shear stress of 270 kPa), the middle and rear shale is damaged and compresses the front, causing it to transform from tensile shear to compressive shear failure. The plastic zone in the rear extends forward and connects with the front ones, forming an overall landslide. Besides, preventing deep landslides caused by hydration through waterproofing, drainage, protection, and support for excavated slopes has proven difficult. Therefore, it is necessary to redesign treatment schemes based on the characteristics of stress, strain, and seepage.

Exploring Genetic Variability, Path Analysis and Divergence in Sorghum (Sorghum bicolor (L.) Moench)

The grain crop known as sorghum [Sorghum bicolor (L.) Moench], which belongs in the Poaceae family, is said to have evolved from Ethiopia or Sudan. This is a crucial crop for food security, especially within the tropical and semi-arid regions in African nations. By terms of long-term domestication and genetic diversity, this crop was native from Ethiopia. showed differences between the crop's cultivated and wild ancestors that gathered within the nation. Due to its enormous diversity of sorghum, which shows innate biological resistant to disease, dryness, and insects in addition to having large lysine content and excellent quality of grain, Ethiopia has become the world's top contributor of germplasm for the sorghum breeding programmes. Ethiopian landraces referred to as "zera zera" sorghum and the generations that sprang of those were used in ICRISAT along with other nations' contemporary sorghum breeding programmes for hybrids creation. Sorghum is at present Ethiopia's second most significant cereal crop after the tef with regard to of its combined area covered and productivity, which means it's used to make injera. Sorghum genotype from Ethiopia is varied and has responded to a variety of rainfall conditions and elevations. Plant breeding starts with the characterisation and recognition of sorghum seeds that offer desired features for improved genetics. When contrast with field trial evaluation, DNA-based molecular markers and PCR-based methods were most effective in characterising and identifying sorghum genotypes which offer desired features since they are unaffected by duration or climate. The most economical method of increasing sorghum production for many applications is genetic enhancement. Gaining more knowledge about sorghum's genetic diversity could be extremely beneficial for improving the crop in terms of quality of food along with other crucial agronomic characteristics. Sorghums from the Ethiopian Centre of Crop Diversity have a vast amount of genetic variety. To effectively gather and conserve this genetic variety before it is overrun and lost, some serious work is required.

Numerical Analysis of Seepage Field Response Characteristics of Weathered Granite Landslides under Fluctuating Rainfall Conditions

The threat and destructiveness of landslide disasters caused by extreme rainfall are increasing. Rainfall intensity is a key factor in the mechanism of rainfall-induced landslides. However, under natural conditions, rainfall intensity is highly variable. This study focuses on the Fanling landslide and investigates the effects of varying rainfall intensity amplitudes, rainfall durations, and total rainfall amounts on landslide behavior. Three experimental groups were established, and ten rainfall conditions were simulated numerically to analyze the seepage field response of the landslide under fluctuating rainfall conditions. The results indicate that (1) there are positive correlations between the final pore pressure and both the amplitude and duration of rainfall intensity; (2) the pore water pressure response in the upper slope changes significantly, initiating deformation; and (3) the total rainfall amount is the most direct factor affecting the pore pressure response and landslide deformation. Compared to long-term stable rainfall, short-term fluctuating rainstorms are more likely to trigger landslides. These findings enhance our understanding of landslide mechanisms under fluctuating rainfall, providing valuable insights for disaster prevention and mitigation.

Implikasi Low Impact Develompent (LID) Untuk Mereduksi Limapasan Pada Ruas Jalan Lingkar Selatan Kota Sukabumi

The condition of the Drainage Network in the South Ring Road section of Sukabumi City has problems when the rainy season arrives, one of the problems faced is the occurrence of runoff on the road and several sub-catchments. Runoff problems in drainage channels are caused by fill of garbage, sedimentation and vegetation that impact on the capacity of channel. It is necessary to conduct a study related to the condition of the existing channel to provide a solution in handling overflows. Primary data used is direct observation at the study site to obtain channel dimensions and channel elevations in existing conditions. Secondary data in the form of maximum rainfall points at the study site (NASA source) for 42 years. Based on the 5-year return period design rainfall calculation with the Log Pearson III Distribution method (selected method), simulated with the Personal Computer Storm Water Management Models. The results of the analysis show that there is flooding at the junction of 4 points in the conditions of the 5-year return period design rainfall. To reduce flooding, it is necessary to evaluate the drainage system by maximizing the function of existing land in each sub-catchment by installing Low Impact Development (LID) instruments in the form of Rain Barrel, Rain Garden and Bio-Retention at a number of sub-catchment points affected by flooding. The simulation results show that there is a reduction in average runoff of 35% so that the installation of LID instruments can be used to minimize the impact of flooding.Keywords:Channel, Drainage, LID, Runoff, Sub-catchment

Productivity Of Various Cocoa Clones (Theobroma Cacao L.) At Different Rainfall Levels In Tettikenrarae Village, Soppeng Regency

Changes in rainfall are one of the causes of declining production in cocoa plants and cause land degradation, thus reducing national cocoa productivity. This study aims to analyze the productivity of various clones of cocoa plants at different rainfall levels so that the relationship between production levels and cocoa productivity at different rainfall levels is known. This study used the observation method. Data collection was done by random sampling in farmers' farms by determining the appropriate sample plants. The sample plants used came from three different clones, namely MCC Clone 01 (M01), MCC Clone 02 (45), and Sulawesi Clone 1 (S1) which were 13 years after planting and still productive. Rainfall data was obtained from available data at the BMKG of South Sulawesi Province. Data analysis was conducted to determine the productivity comparison of three cocoa clones at different rainfall levels. The results showed that: 1) Different rainfall levels affect the productivity of various cocoa clones in Tettikenrarae Village, Soppeng Regency. This can be seen in the parameters of number of seeds and weight of seeds, with productivity respectively for clone MCC 02 amounting to 4350.66 kg, clone S1 4326.78 kg, and clone MCC 01 with a production of 3863.29 kg. 2) Productivity of cocoa clones in Tettikenrarae Village, Soppeng Regency is best in moderate rainfall conditions, where clone MCC 02 has the highest productivity of 1820.47 kg which occurs in rainfall of 100 - 300 mm.

Environmental and genetic drivers of physiological and functional traits in a key canopy species

The resilience of forests worldwide is challenged by climate change. Large-scale tree mortality and dieback events have been documented across continents in recent decades. The adaptive capacity of forests is important for predicting forest resistance and resilience to future climates yet remains largely unknown. We grew 12 populations of a widespread foundation tree species (Corymbia calophylla), originating from different temperature and rainfall regimes, in two common garden trials in Western Australia that had similar temperature but contrasting rainfall conditions. We quantified intraspecific trait variation at these two sites to estimate genetically determined trait variation with climate origin (genetic adaptation) and trait variation associated with environment (phenotypic plasticity). We aimed to determine the 1) contribution of genetic and environmental factors on growth, functional, and physiological trait variation; 2) coordination of leaf traits within the context of the leaf economic spectrum (LES) in variable rainfall conditions; and 3) role of local or regional climate adaptation influencing tree growth and water use efficiency. Growth and physiological traits were differentially expressed across populations and sites, highlighting the importance of genetic adaptation and phenotypic plasticity. Leaf traits reflected a more water conservative strategy with higher water use efficiency, high foliar nitrogen content, and low specific leaf area, as predicted by the LES, in trees at the dry site measured in autumn after the warm summer. Local adaptation was detected in growth and leaf water use efficiency traits at the regional climate, not the local population, scale. Plants from the cool region had greater performance than those from the warm region in most plant traits. Home-site rainfall was not a good predictor of trait expression. The capacity of C. calophylla to respond to low water availability through genetic adaptation and phenotypic plasticity may enable it to maintain optimal performance in drier conditions associated with climate change.

The impacts of film mulching and ridging on N2O emissions, relevant functional genes, and microbial communities in rain-fed potato fields

Rain-fed potato (Solanum tuberosum) fields in drylands significantly contribute to nitrous oxide (N2O) emissions, making them an important focus of agricultural greenhouse gas research. Film mulching and ridging are key agricultural methods in potato cultivation. Investigating the impact of these methods on N2O emissions, nitrifying/denitrifying functional genes, and microbial communities can provide a theoretical basis for soil emission reduction and more sustainable dryland agriculture. We examine the effects of flat tillage with mulching, ridge tillage with mulching, flat tillage without mulching, and ridge tillage without mulching, on potato fields under natural rainfall conditions in Wuchuan County, China. N2O emission fluxes were monitored using a static (dark) chamber and gas chromatography. Real-time quantitative PCR (q-PCR) was used to quantify abundances of nitrifying and denitrifying bacteria related to N2O emissions at various potato-growth stages. Illumina high-throughput sequencing was used to investigate microbial community structure by targeting 16S rRNA genes; related soil elements (soil temperatures and moisture) are analyzed. Mulching and ridging indirectly influence N2O emissions, nitrifying/denitrifying functional gene copy numbers, and microbial community structure by altering soil temperature and moisture. Cumulative N2O emissions and emission intensity were both consistently higher in ridge tillage with mulching during the potato-growing period. Ammonia-oxidizing archaea are the main microorganisms that control N2O emissions, with nitrification-coupled denitrification also being an important mechanism contributing to high N2O emissions during soil dry–wet cycles. Increased soil temperature and moisture elevated N2O emissions and functional gene copy numbers. The combination of mulching and ridging effectively uses the characteristics of both practices, making Nitrospira the dominant genus, and significantly increases N2O emissions.

Quantifying the effects of rock fragments embedding vs. Covering on soil erosion in karst sloping cropland

Rock fragments can alter soil structure, thus profoundly affecting soil properties, hydrological and erosion processes. Hence, it is essential to quantify the role of rock fragments in soil-water processes in order to fully grasp their complex impacts on soil erosion. In this study, the effect of vertical embedded (VE) and covered (CV) rock fragments on runoff and soil loss of sloping cropland were investigated in plot scale through field monitoring experiments, with bare land (CK) as a control. Results showed that surface runoff from VE decreased by 24.93% compared to bare land, while subsurface flow and underground flow increased by 12.47% and 10.85%, respectively. Similarly, compared to bare land, CV decreased surface runoff by 14.08% and increased subsurface flow and underground flow by 7.09% and 7.29% respectively. Consequently, both VE and CV effectively decreased surface runoff and enhanced the proportion of rainwater converted into subsurface flow and underground flow (P < 0.05). Simultaneously, the benefits of VE in reducing surface runoff and promoting rainwater infiltration was found to be more significant than that of CV (P < 0.05). In terms of soil erosion, compared with bare land, VE reduced the surface soil loss rate by an average of 41%, while CV instead increased the surface soil loss rate by an average of 3.64%, and these changes were both statistically significant (P < 0.05). Moreover, soil erosion from subsurface flow and underground flow may be a long-term accumulation process, resulting in insignificant differences in soil erosion rates between treatments in this study (P > 0.05). Therefore, in studying the impact of rock fragments on soil erosion in karst sloping cropland, the focus should be on soil erosion caused by surface runoff. Additionally, the impact of rock fragments on the transformation of rainwater and soil erosion was limited by rainfall conditions, with VE showing a more prominent effect in preventing soil erosion under heavy rainfall conditions. Overall, the impact of rock fragments on soil erosion varies depending on their distribution patterns in the topsoil. It is necessary for these differences to be incorporated into process-based runoff and erosion models.