Initial Soil Conditions Research Articles

Asian knotweed’s impacts on soil chemistry and enzyme activities are higher in soils with low-nutrient status

Invasive alien plants such as Reynoutria spp. can drastically affect the composition of plant communities. Yet, whether and how these species also affect soil physicochemical properties and microbial functioning is still an unresolved question in the literature. Using a space-for-time substitution approach comparing invaded to uninvaded adjacent plots, we estimated the impacts of Reynoutria on soil biochemistry across nine contrasted sites in France by measuring soil carbon content, nutrient availability and enzyme activities. Soil under Reynoutria displayed higher carbon, nitrogen and phosphorus contents but no differences were detected regarding enzyme activities between invaded and uninvaded sites. Moreover, the magnitude of Reynoutria’s effects differed depending on local conditions, with greater effects when total carbon and phosphorus-related enzymes were relatively low. These data highlight that changes in soil nutrient availability might be primarily due to direct effects of Reynoutria on soil properties and microbial functioning. Higher impacts were observed in soils with low-nutrient status, suggesting a ‘niche construction ability’ of Reynoutria. Our results underscore the necessity of considering the context-dependency of Reynoutria on soil biochemistry and highlight that the impact of alien species belowground functioning depends on initial soil conditions.

Responses of soil moisture at different topographic positions to rainfall events along a steep subtropical forested hillslope

AbstractUnderstanding the dynamic response of soil moisture to rainfall is crucial for describing hydrological processes at the hillslope scale. However, because of sparse monitoring coupled with the complexity of water movement and steep topography, the findings of rainfall‐related soil moisture dynamics have not always been consistent, indicating a need for systematic investigations of soil moisture dynamics and infiltration patterns following rainfall inputs at multiple topographic positions along a hillslope. This study aimed to examine the nature of these responses by characterizing and quantifying the response amplitude, rate and time for 37 large rainfall events at 25 combinations of topographic positions and soil depths along a steep forested hillslope. Our results showed that soil moisture responses under different rainfall patterns could be attributed to one or the other rainfall characteristics, such as rainfall intensity and amount. However, soil moisture dynamics at different hillslope positions after rainfall varied widely due to the controls of soil properties, topography, and non‐equilibrium flow. Preferential flow was more evident under dry initial soil conditions than under wet initial soil conditions. Findings of this study reveal that the dynamic response patterns of soil moisture to rainfall do not always follow topographic controls, which can improve our understanding of water cycling related to the infiltration process at the hillslope scale, and support water resources management in subtropical mountain ecosystems.

Comprehensive evaluation of factors influencing selenium fertilization biofortification.

Dietary selenium (Se) deficiency, stemming from low Se concentrations in agricultural products, threatens human health. While Se-containing fertilizers can enhance the Se content in crops, the key factors governing Se biofortification with Se fertilization remain unclear. This study constructed a global meta-analysis dataset based on field experiments comprising 364 entries on Se content in agricultural products and 271 entries on their yield. Random forest models and mixed effects meta-analyses revealed that plant types (i.e., cereals, vegetables, legumes, and forages) primarily influenced Se biofortification, with Se fertilization rates being the next significant factor. The random forest model, which included variables like plant types, Se fertilization rates, methods and types of Se application, initial soil conditions (including Se content, organic carbon content, and pH), soil types, mean annual precipitation, and temperature, explained 82.14% of the variation in Se content and 48.42% of the yield variation in agricultural products. For the same agricultural products, the increase in Se content decreased with higher rates of Se fertilization. The increase in Se content in their edible parts will be negligible for cereals, forages, legumes, and vegetable crops, when Se fertilization rates were 164, 103, 144, and 147 g Se ha-1, respectively. Conversely, while low Se fertilization rates enhanced yields, high rates led to a yield reduction, particularly in cereals. Our findings highlight the need for balanced and precise Se fertilization strategies to optimize Se biofortification benefits and minimize the risk of yield reduction. © 2024 Society of Chemical Industry.

Optimal Soil, Climate, and Management Factors for Maximizing Crop Yield and Soil Nutrients in a Rice–Oilseed Rotation System with Straw Return

Straw return (SR) has been widely recommended as a conservation agricultural practice in China. However, the effects of SR on crop yield and soil properties are inconsistent across studies of rice–oilseed rape cropping systems in China. This study aimed to investigate the effects of SR on crop yield and soil nutrient content in a rice–oilseed rotation system, and to understand the mechanism of straw return on the difference in yield increases between rice and oilseed rape. Additionally, suitable climate factors, soil properties, and agricultural practices were identified to achieve maximum increases in yield and soil nutrients in a rice–oilseed rotation under SR. This paper is based on a meta-analysis of 1322 observations from 83 peer-reviewed studies to evaluate the effects of climate, initial soil conditions, and agricultural management practices on rice and oilseed rape yields and soil nutrients under SR. The results showed that the responses of oilseed rape and rice yield remained positive, with 12.37% and 6.54% increases, and were significantly higher under SR than the control (no SR). Moreover, SR significantly increased the contents of several soil nutrients (soil organic carbon (SOC), total nutrients, available nutrients) and microbial biomass carbon (MBC) and nitrogen (MBN). Interestingly, the increase in crop yields was attributed to the increase in SOC, total nitrogen, and available potassium. Additionally, the increase in yields was mainly affected by climate factors, initial soil properties, and agronomic practices. For example, both mean annual temperature (MAT) and mean annual precipitation (MAP) had a positive correlation with crop yield increases under SR (p < 0.01). Initial soil conditions such as low SOC and total nitrogen content were more suitable for increased rice yield under SR, while the opposite was true for increased oilseed rape yield. Without fertilization, the SR did not significantly improve crop yield and soil nutrients, while it was more pronounced with N fertilization at 150–180 kg hm−2. The positive effect of SR on crop yields is more evident with plowing tillage, whereas the SR caused the highest increase in soil nutrients with the no-tillage condition. These findings have important implications for further improving crop yield, SOC, and soil nutrients in the Chinese rice–oilseed cropping system through straw return.

Impact of Initial Soil Conditions on Soil Hydrothermal and Surface Energy Fluxes in the Permafrost Region of the Tibetan Plateau

Impact of Initial Soil Conditions on Soil Hydrothermal and Surface Energy Fluxes in the Permafrost Region of the Tibetan Plateau

Effects of municipal waste compost on microbial biodiversity and energy production in terrestrial microbial fuel cells

Microbial Fuel Cells (MFCs) transform organic matter into electricity through microbial electrochemical reactions catalysed on anodic and cathodic half-cells. Terrestrial MFCs (TMFCs) are a bioelectrochemical system for bioelectricity production as well as soil remediation. In TMFCs, the soil is the ion-exchange electrolyte, whereas a biofilm on the anode oxidises organic matter through electroactive bacteria. Little is known of the overall microbial community composition in a TMFC, which impedes complete exploitation of the potential to generate energy in different soil types. In this context, an experiment was performed to reveal the prokaryotic community structure in single chamber TMFCs with soil in the presence and absence of a municipal waste compost (3% w/v). The microbial community was assessed on the anode and cathode and in bulk soil at the end of the experiment (54 days). Moreover, TMFC electrical performance (voltage and power) was also evaluated over the experimental period, varying the external resistance to improve performance. Compost stimulated soil microbial activity, in line with a general increase in voltage and power. Significant differences were observed in the microbial communities between initial soil conditions and TMFCs, and between the anode, cathode and bulk soil in the presence of the compost. Several electroactive genera (Bacillus, Fulvivirga, Burkholdeira and Geobacter) were found at the anode in the presence of compost. Overall, the use of municipal waste compost significantly increased the performance of the MFCs in terms of electrical power and voltage generated, not least thanks to the selective pressure towards electroactive bacteria on the anode.

Transferred communities of arbuscular mycorrhizal fungal persist in novel climates and soils

Symbiotic mycorrhizal fungi strongly influence plant establishment and growth particularly in harsh environments, whereby sympatric, presumably co-adapted symbionts are considered particularly beneficial. However, the response of transferred sympatric mycorrhizal fungal communities to new environments remains largely ignored. We therefore studied the relative importance of initial inoculum, soil and climatic conditions on the composition, diversity and root colonization ability of arbuscular mycorrhizal fungal (AMF) communities. To do so, we analyzed the AMF communities in an extensive experiment with two ecotypes of Bouteloua gracilis planted in their sites of origin and in four new sites differing in climate and soil properties.After three seasons of growth, the sympatric AMF communities were little changed by the new abiotic conditions. The composition of the AMF communities in plant roots was most strongly determined by the initial inoculum, while the contribution of divergent soil and climatic conditions was an order of magnitude smaller. The levels of root colonization by AMF, in contrast, were significantly influenced by climatic and soil conditions and did not differ among communities of different origins. Their pattern indicates that mycorrhiza formation is facilitated in the plant's sympatric soil and climatic conditions, but also that transferred AMF communities adjust mycorrhiza formation to new abiotic conditions.

Is green manure a viable substitute for inorganic fertilizer to improve grain yields and advance carbon neutrality in paddy agriculture?

Green manure is a widely applied to increase grain yield, while it also attributes to greenhouse gas (GHG) emissions in agriculture ecosystems. Combining green manure with inorganic fertilizer inputs is a common practice that can influence soil GHG emissions and grain yield, however, its impacts on grain yield and global warming potential (GWP) under different initial soil conditions before rotating experiments and agronomic management in paddy fields remain unclear. We synthesized 508 data pairs to evaluate the responses of CO2 emissions, CH4 emissions, N2O emissions, and grain yield to combined inputs of green manure plus inorganic fertilizer compared with only inorganic fertilizer application. Our findings indicate that both inorganic fertilizer plus extra green manure (GM-E) and green manure substitutes for inorganic fertilizer (GM-S) could increase CO2 emissions (22.5 %−76.8 %), CH4 emissions (100 %−103 %), N2O emissions (29.8 %−50.9 %), and yield (2.21 %−19.6 %). Except for GM-E, which showed a non-significant increase in grain yield. The initial soil properties before rotating experiments, the types and timing of green manure application were key drivers of GHG emissions and yield, and extra green manure applied in areas with low initial soil pH and high C:N can increase GWP and yield. Overall, the mixed green manure application had greater impact than leguminous or non-leguminous green manure applied alone. The responses of GHG emissions and yield to GM-S were modulated by mean annual precipitation and initial soil properties before rotating experiments, and green manure substitutes for inorganic fertilizer in areas with high initial soil pH and low C:N can increase GWP and yield. Meanwhile, excessive precipitation caused a reduction in yield and a significant increase in GWP intensity. Our results showed that extra green manure applications of less than 68.1 kg N ha−1 would not significantly increase GWP. Therefore, an effective green manure strategy can achieve a win-win situation for the dual challenge of agricultural production and climate change mitigation.

Effects of Water Control and Nitrogen Addition on Functional Traits and Rhizosphere Microbial Community Diversity of Haloxylon ammodendron Seedlings

Water and nitrogen sources have always been the primary limiting factors for vegetation growth in arid and semi-arid regions and play an important role in the physiological ecology of vegetation. In this work, we studied the effects of water deficit and nitrogen addition on the physiological traits and rhizosphere bacterial microbial community of Haloxylon ammodendron seedlings in sterilized and non-sterilized soil habitats. A pot experiment was conducted to control the water and nitrogen sources of H. ammodendron seedlings. The water deficit treatment was divided into two groups based on gradient: a normal water group (CK, 70% field water holding capacity) and water deficit group (D, 30% field water holding capacity). The nitrogen addition treatment was divided into a no addition group (CK, 2.8 mg·kg−1) and addition group (N, 22.4 mg·kg−1). At the end of the growing season, the biochemical indexes of H. ammodendron seedlings were measured, and the rhizosphere soil was subjected to 16S rDNA-high-throughput sequencing to determine the rhizosphere bacterial community composition of H. ammodendron seedlings under different treatments. The results showed that the root-to-crown ratio of H. ammodendron seedlings increased significantly (p < 0.05) under the water deficit treatment compared to the control and nitrogen addition treatments, indicating that H. ammodendron seedlings preferred to allocate biological carbon to the lower part of the ground. In contrast, plant height and root length were significantly lower (p < 0.05) under water deficit treatment compared to the control, and no significant change was observed under water deficit and nitrogen addition compared to the control, indicating that water deficit inhibited the growth of H. ammodendron seedlings and nitrogen addition mitigated the effect of water deficit on the growth of H. ammodendron seedlings. Under sterilized soil conditions, both water deficit and nitrogen addition significantly increased the abundance and diversity of bacterial communities in H. ammodendron seedlings (p < 0.05). Conversely, under non-sterilized conditions, both inhibited the diversity of microbial bacterial communities, and the microbial characteristic species under different controls were different. Therefore, in the short-term experiment, H. ammodendron seedlings were affected by water deficit and allocated greater quantities of biomass to the underground part, especially in the non-sterile microbial environment; different initial soil conditions resulted in divergent responses of rhizosphere bacterial communities to water deficit and nitrogen addition. Under different initial soil conditions, the same water deficit and nitrogen addition treatment will lead to the development of distinct differences in rhizosphere bacterial community composition.

Rapid increase in soil organic carbon and structural stability in a sandy loam soil following conversion from long-term arable to semi-natural grassland irrespective of initial soil conditions

Converting arable land to semi-natural grassland has the potential to restore soil structural stability (SSS) and increase soil organic carbon (SOC) storage. However, the effect of the initial soil C level and conditions on the changes following introduction of grassland is poorly understood. We quantified changes in SSS and SOC in topsoil from the Askov straw disposal and cover cropping experiment initiated in 1981 in Denmark before and after its conversion to semi-natural grassland in 2020. Due to different straw input and cover crop use in the arable phase, the grass was established on soils with different initial conditions (11.9–17.9 g C kg−1 oven-dry soil). Soils sampled in 2019 and 2021 from plots subjected to different treatments in the arable phase were analyzed for clay dispersibility measured on two macro-aggregate sizes (ClayDis 1–2 mm and ClayDis 8–16 mm), wet stability of aggregates (WSA) and SOC. Irrespective of initial soil conditions, introduction of semi-natural grassland resulted in a rapid increase in SOC, a decline in ClayDis 1–2 mm and no change in WSA. The relative change in ClayDis 1–2 mm was larger than the change in SOC, and the slope for the relationship between SOC and ClayDis 1–2 mm decreased after conversion to grassland. Based on these observations, we suggest that the additional driver in play was aggregate-binding and -bonding agents being persistent due to the absence of tillage following the conversion to grassland. Notably, changes in SOC and SSS were similar regardless of initial soil conditions, which may be related to a similar productivity in the semi-natural grassland and soil C saturation.

The International Heat Stress Genotype Experiment for modeling wheat response to heat: field experiments and AgMIP-Wheat multi-model simulations

The data set contains a portion of the International Heat Stress Genotype Experiment (IHSGE) data used in the AgMIP-Wheat project to analyze the uncertainty of 30 wheat crop models and quantify the impact of heat on global wheat yield productivity. It includes two spring wheat cultivars grown during two consecutive winter cropping cycles at hot, irrigated, and low latitude sites in Mexico (Ciudad Obregon and Tlaltizapan), Egypt (Aswan), India (Dharwar), the Sudan (Wad Medani), and Bangladesh (Dinajpur). Experiments in Mexico included normal (November-December) and late (January-March) sowing dates. Data include local daily weather data, soil characteristics and initial soil conditions, crop measurements (anthesis and maturity dates, anthesis and final total above ground biomass, final grain yields and yields components), and cultivar information. Simulations include both daily in-season and end-of-season results from 30 wheat models. All data are available via DOI 10.7910/DVN/CJJBSR.

A high-yielding traits experiment for modeling potential production of wheat: field experiments and AgMIP-Wheat multi-model simulations

Grain production must increase by 60% in the next four decades to keep up with the expected population growth and food demand. A significant part of this increase must come from the improvement of staple crop grain yield potential. Crop growth simulation models combined with field experiments and crop physiology are powerful tools to quantify the impact of traits and trait combinations on grain yield potential which helps to guide breeding towards the most effective traits and trait combinations for future wheat crosses. The dataset reported here was created to analyze the value of physiological traits identified by the International Wheat Yield Partnership (IWYP) to improve wheat potential in high-yielding environments. This dataset consists of 11 growing seasons at three high-yielding locations in Buenos Aires (Argentina), Ciudad Obregon (Mexico), and Valdivia (Chile) with the spring wheat cultivar Bacanora and a high-yielding genotype selected from a doubled haploid (DH) population developed from the cross between the Bacanora and Weebil cultivars from the International Maize and Wheat Improvement Center (CIMMYT). This dataset was used in the Agricultural Model Intercomparison and Improvement Project (AgMIP) Wheat Phase 4 to evaluate crop model performance when simulating high-yielding physiological traits and to determine the potential production of wheat using an ensemble of 29 wheat crop models. The field trials were managed for non-stress conditions with full irrigation, fertilizer application, and without biotic stress. Data include local daily weather, soil characteristics and initial soil conditions, cultivar information, and crop measurements (anthesis and maturity dates, total above-ground biomass, final grain yield, yield components, and photosynthetically active radiation interception). Simulations include both daily in-season and end-of-season results for 25 crop variables simulated by 29 wheat crop models.

Eco-hydrological modeling of soil wetting pattern dimensions under drip irrigation systems

Reliable information on the horizontal and vertical dimensions of the wetted soil beneath a point source is critical for designing accurate, cost-effective, and efficient surface and subsurface drip irrigation systems. Several factors, including soil properties, initial soil conditions, dripper flow rate, number of drippers, spacing between drippers, irrigation management, plant root characteristics, and evapotranspiration, influence the dimensions and shape of wetting patterns. The objective of this study was to briefly review previous studies, collect the analytical, numerical, and empirical models developed, and evaluate the effectiveness of the most common empirical method for predicting the dimensions of soil wetted around drippers using measured data from field surveys. With this review study, we aim to promote a better understanding of soil water dynamics under point-source drip irrigation systems, help improve soil water dynamics under point-source drip irrigation systems, and identify issues that should be better addressed in future modeling efforts. A drip irrigation system was configured with three different emitters with different capacities (2, 4, and 8 l h-1) in the point source to determine the soil wetting front under the point source. The five most selected empirical equations (Al-Ogaidi, Malek and Peters, Amin and Ekhmaj, Li and Schwartzman and Zur) were statistically analyzed to test the efficiency in sandy loam soil. According to the results of the field investigation, statistical comparisons of the empirical models with the field investigation data were performed using the mean absolute error (MAE), root mean square error (RMSE), Nash–Sutcliffe model efficiency (CE), and coefficients of determination (R2). The advanced simulation of the wetting front was used based on the best accuracy of the selected empirical model. In general, the Li model (MAE, RMSE, EF, and R2 were 0.698 cm, 0.894 cm, 0.970 cm2 cm-2, and 0.970, respectively, for the wetted soil width and 1.800 cm, 1.974 cm, 0.927 cm2 cm-2, and 0.986, for the vertical advance) proved to be the best after statistical analysis with field data.

Assessment of GPM Satellite Precipitation Performance after Bias Correction, for Hydrological Modeling in a Semi-Arid Watershed (High Atlas Mountain, Morocco)

Due to its important spatiotemporal variability, accurate rainfall monitoring is one of the most difficult issues in semi-arid mountainous environments. Moreover, due to the inconsistent distribution of gauge measurement, the availability of precipitation data is not always secured and totally reliable at the instantaneous time step. As a result, earth observation of precipitation estimations could be an alternative for overcoming this restriction. The current study presents a framework for either the hydro-statistical evaluation and bias correction of the Global Precipitation Measurement (GPM) Integrated Multi-SatellitE Retrievals version 06 Early (IMERG-E), Late (IMERG-L), and Final (IMERG-F) products. On a sub-daily duration, from the Taferiat rain gauge-based station, which was used as a benchmark from 1 September 2014 to 31 August 2018. Statistical analysis was performed to examine each precipitation product’s performance. The results showed that all Post_Real_Time and Real_Time IMERG had a high level of awareness accuracy. The IMERG-L results were statistically similar to the gauge data, succeeded by the IMERG-F and IMERG-E. The Cumulative Distribution Function (CDF) has been employed to adjust the precipitation values of the three IMERG products in order to decrease bias estimation. The three products were then integrated into the “HEC-HMS” hydrological model to assess their dependability in flow modeling. Six flood occurrences were calibrated and validated for each product at 30-minute time steps. With a mean Nash-Sutcliffe coefficient of NSE 0.82, the calibration findings demonstrate that IMERG-F provides satisfactory hydrological performance. With an NSE = 0.80, IMERG-L displayed good hydrological utility, slightly better than IMERG-E with an NSE = 0.77. However, when the flood events were validated using the initial soil conditions, IMERG F and IMERG E overestimated the discharge by 13% and 10%, respectively. While IMERG L passed the validation phase with an average score of NSE = 0.69.

Modeling tire-soil compression resistance on artificial soil using the scaling law of pressure-soil sinkage relationship

Semi-empirical traction models utilize soil parameters estimated from ASABE cone and flat plate soil sinkage data; however, limited studies apply the scaling law of the soil measurement tool to a full-scale tire-to-soil system for various initial soil conditions. This study investigated the effects of three scaled plates (size and shape) and two soil bulk density conditions on pressure-sinkage relationships in artificial soil. Rectangular estimated tire-soil shape and a contact area of 484 cm2 were measured from vertical loading of an LT235/75R15 tire (179 kPa inflation pressure and 8 kN vertical load) in a soil bin test on an artificial soil. Pressure-sinkage data were collected on an artificial soil column at 1.21 Mg/m3 soil bulk density (66% of Proctor density) and 1.41 Mg/m3 soil bulk density (75% of Proctor density) initial conditions using circular, rectangular, and square plates, each at three scaled areas (λ = 0.5, λ = 0.25, and λ = 0.125, where λ = 1 is the tire-soil estimated footprint area from the single tire soil bin test). A scaling law with a strong correlation was established between the geometric scale and the energy expended in compressing the soil. The plate pressure data for λ = 0.125 exhibited a relatively linear increase in pressure as depth increased for loose soil, similar to the soil cone penetrometer data. The pressure-sinkage data for λ = 0.5 exhibited a trend similar to existing models, but coefficients differed for the two initial soil bulk densities. The study demonstrates applying a scaling law to simulate a tire-soil system on soft and dense soils.

Integrated effects of vermicompost, climatic factors and soil mixing on selected soil fertility indicators

A field experiment was carried out to investigate the effects of vermicompost (0, 10, and 15 tha-1), climatic elements i.e. soil moisture (50%, 70%, and 100%) and elevation of soil temperature (1 to 20C) on the physico-chemical properties and nutrient availability of post-harvest calcareous-acid mixed soils after rice production. A total of 18 treatments assembling the afore-mentioned doses was applied. The analyses of the soils demonstrated significant variation in effects (p ≤0.05) of the treatments on both the available nutrient status and the physicochemical properties of soils. Except for available sulfur; soil pH, EC, organic carbon (OC), available nitrogen, phosphorous, potassium, calcium, and sodium were detected in the higher amounts in 1:1 (calcareous : acid-soils) mixed soils than those of 1:3 mixed counterpart both in initial and post-harvest soil conditions. The highest levels of soil pH, OC, available P and Zn were determined in the treatment T13. Whereas, treatment T6 proved to be the best dose for the highest availability of Ca and Mg. The treatments T1, T2, T11, and T16 were recorded to have the lower OC, available N, P, Ca, Mg, Zn and S contents in soils. In particular, the availability of Na was found to be in lesser amounts in all the subplots. In a nutshell, most of the treatments exerted favourable influence in maintaining a healthy level of soil physico-chemical parameters owing to their inherent characteristics. Dhaka Univ. J. Biol. Sci. 32(1): 119-134, 2023 (January)

岩溶区不同土地利用方式下土壤CO2排放模拟研究

PDF HTML阅读 XML下载 导出引用 引用提醒 岩溶区不同土地利用方式下土壤CO2排放模拟研究 DOI: 10.5846/stxb202111223290 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目（42072278，42177248）；贵州省科技计划项目（黔科合支撑[2020]4Y013号） Simulation experiment on soil CO2 emission by different land uses in karst area Author: Affiliation: Fund Project: The national natural science foundation of China(42072278,42177248); Guizhou Science and Technology Supporting Plan (No. 2020-4Y013) 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:土地利用变化作为全球气候变化研究的重要内容之一，对土壤CO2的排放具有重要影响。岩溶区石漠化治理过程中植被恢复伴随着土地利用方式的转变，其对土壤CO2排放的影响有待进一步研究。基于控制性实验，以土壤、岩溶含水介质初始条件相同，仅土地利用方式不同的贵州普定沙湾模拟试验场为研究对象，通过1年的土壤CO2浓度和通量数据，研究岩溶区不同土地利用方式下土壤CO2的排放规律及其影响因素。结果表明：（1）土壤CO2的浓度和通量具有明显的季节变化规律，不同季节下的土壤CO2通量呈现昼夜变化规律，温度和降雨影响着土壤CO2的排放，前者可促进排放量，后者可抑制排放量，且不同土地利用方式受影响的程度不同；（2）耕作活动也会影响土壤CO2的排放，耕作使得土壤变得松散，加上岩溶区下伏基岩的溶蚀作用，增加了土壤CO2向含水层的扩散，导致春季耕地表现为负通量；（3）不同土地利用方式下土壤CO2的年排放量不同，具体为草地（897.53 tC km-2 a-1）>灌木地（258.15 tC km-2 a-1）>耕地（207.66 tC km-2 a-1）>裸土地（92.68 tC km-2 a-1），究其原因，主要受不同土地利用下植被生物量和土壤有机碳含量的影响；（4）不同土地利用下的土壤有机碳含量为草地（29.33 g/kg）>灌木地（23.31 g/kg）>耕地（22.08 g/kg）>裸土地（19.00 g/kg），鉴于这些土壤的初始性质相同，研究发现随着土地利用方式的改变，除无植被的裸土地土壤有机碳含量减小外，其余有植被的类型均有增加，且增加的程度和植被覆盖的程度有关。综上，不同土地利用类型可以通过影响上覆植被的生物量和土壤有机碳含量，进而控制土壤CO2的排放，而排放强弱与温度、降雨和耕作活动有关，可以通过土地利用方式的调整来增加土壤有机质含量和土壤储碳。 Abstract:As one of the important parts of global climate change research, land use change plays a significant role in soil CO2 emission. In karst area, vegetation has been restored in the process of rocky desertification control, accompanied by the change of land use, and its impact on soil CO2 emission needs to be further clarified. Based on the controlled experiment, with the same initial conditions of soil and karst aqueous media but different land uses, the Shawan Test Site at Puding, Guizhou was chosen to study the emission law and influencing factors of soil CO2. Through the soil CO2 concentration and flux data in a hydrological year, our results demonstrated that:(1) the soil CO2 concentration and flux showed obviously seasonal variations, and the soil CO2 flux had apparent diurnal variation in different seasons. They were mainly controlled by temperature and rainfall. The former could increase the emission, while the latter could decrease the emission, and the increased or decreased degrees were related to land uses. (2) Farming activities affected the soil CO2 emission as well. Due to the dissolution of the underlying carbonate rock in karst area, farming activities could make the soil loose and increase the diffusion of soil CO2 to the aquifer, resulting in negative soil CO2 flux of cultivated land in spring. (3) The annual emission of soil CO2 under different land uses were grassland (897.53 tC km-2 a-1) > shrub land (258.15 tC km-2 a-1) > cultivated land (207.66 tC km-2 a-1) > bare soil land (92.68 tC km-2 a-1). It was found that they were mainly dominated by vegetation biomass and soil organic carbon content under different land uses. (4) The contents of soil organic carbon were grassland (29.33 g/kg) > shrub land (23.31 g/kg) > cultivated land (22.08 g/kg) > bare soil land (19.00 g/kg). Given the same initial properties of these soils, we found that with the change of land use, except for the soil organic carbon content in non-vegetated bare soil land decreased, the other types increased, and the increased degree was related to the degree of vegetation coverage. Therefore, land use types could control soil CO2 emission by affecting the biomass of overlying vegetation and the soil organic carbon content, and the emission intensity is related to temperature, rainfall process and farming activities. Further, we think that the content of soil organic matter and soil carbon storage could be increased through the adjustment of land use. 参考文献 相似文献 引证文献

The laterally confined consolidation of initially compacted and wetted swelling clay

This paper describes the laterally confined consolidation of an Israeli clay following compaction and swelling on wetting, including the measurement of lateral stresses. The results of the tests are compared to those obtained during consolidation of the clay from an initially slurried condition. In comparing the compression and expansion indices relative to vertical, lateral and mean stress, it was found that they varied, depending on the initial, preparation conditions; the values approached the slurried values with decreasing initial dry density. During unloading, the expansion indices were found to be independent of initial conditions, and essentially the same as those of the slurried soil. The coefficient of lateral earth pressure at rest during loading, K0, of the compacted and then wetted specimens was found to be reasonably constant regardless of initial soil conditions, but significantly higher than the value of the slurried soil. However, during unloading, the relationship between the normalized coefficients of lateral earth pressure at rest, K0'/K0, and the overconsolidation ratio, OCR, was found to be essentially the same as that obtained for the slurried soil.

Deciphering nitrous oxide emissions from tropical soils of different land uses

Tropical regions are hotspots of increasing greenhouse gas emissions associated with land-use change. Although many field studies have quantified soil fluxes of nitrous oxide (N2O; a potent greenhouse gas) from various land uses, the driving mechanisms remain uncertain. Here, we used tropical soils of diverse land uses and actively manipulated the soil moisture (35%, 60%, and 95% water-filled pore space [WFPS]) and substrate supply (control, nitrate, and nitrate plus glucose) to investigate the responses of N2O emissions with short-term incubations. We then identified key factors regulating N2O emissions out of a series of soil physicochemical and biological factors and explored how these factors interacted to drive N2O emissions. Land-use changes from primary forest to oil palm or Acacia plantation risks emitting more N2O, whereas low emissions could be maintained by conversion to Macaranga forest or Imperata grassland; these laboratory observations were corroborated by a literature synthesis of field N2O measurements across tropical regions. Soil redox potential (Eh) and labile organic nitrogen (LON; amino acid mixture, arginine, and urea) mineralization were among the factors with greatest influence on N2O emissions. In contrast to common understandings, the control of WFPS over N2O emissions was largely indirect, and acted through Eh. The mineralization of LON, particularly arginine, potentially played multiple roles in N2O production (e.g., bottlenecks of nitrifier-denitrification or simultaneous nitrification-denitrification versus substrate competition for co-denitrification). Structural equation models suggest that soil-environmental factors of different levels (from distal including land use, soil moisture, and pH to proximal such as LON mineralization) drive N2O emissions through cascading interactions. Overall, we show that, despite identical initial soil conditions, land conversion can substantially alter the N2O emission potential. Also, collectively considering soil-environmental regulators and their interactions associated with land conversion is crucial to predict and design mitigation strategies for N2O emissions from land-use change.

Economic analysis of irrigation in the production system of soybean and second‐season maize in sandy soil areas in Brazil

AbstractThe objective of the present work was to perform an economic analysis of centre‐pivot irrigation implantation on a sandy soil area with different previous land uses. Thus, it was possible to analyse three initial soil conditions inside (irrigated) and outside (rainfed) the centre pivot. The opening area (P1) was characterized by soybean planting for the first time after degraded pasture, P2 consisted of the second year of harvesting soybean/maize second season, and P3 consisted of the third year of harvest. Two crops were evaluated: soybean and maize. The centre‐pivot irrigation system was not profitable at the earliest stage of soil recovery (P1) immediately after degraded pasture because soil fertility limited yields. There was a 23% and 33% increase in soybean yield for the areas with 2 years (P2) and 3 years (P3) of soil recovery, respectively, compared to the first year. However, second‐season maize had an increased yield of 19% for the third‐year area (P3) compared to the first year (P1). Profit increased from P3 to P1 by $1541 ha−1 for soybean, $2654 ha−1 for maize and $2097 ha−1 overall. Irrigation treatments increased profit by 45%.