Average Soil Moisture Content Research Articles

Effects of Water, Fertilizer and Heat Coupling on Soil Hydrothermal Conditions and Yield and Quality of Annona squamosa

Seasonal drought and summer soil high-temperature stress in Southern China often lead to decreased yield and quality of Annona squamosa. It is important to explore reasonable and effective water and fertilizer management measures as well as cover measures to improve the soil hydrothermal conditions in orchards to realize the increase in yield and quality of Annona squamosa. This study involved a two-year (2022–2023) field experiment in Yun County, Lincang City, Yunnan Province, using three factors and a three-level orthogonal test, resulting in nine different experimental treatments for water, fertilizer and heat. The three irrigation levels were W1 (soil moisture content of 55% of field moisture capacity), W2 (soil moisture content of 75% of field moisture capacity) and W3 (soil moisture content of 85% of field moisture capacity). The three fertilizer levels were F1 (1666 kg·hm−2), F2 (2083 kg·hm−2) and F3 (2500 kg·hm−2), and the three cover methods were A1 (no cover), A2 (fresh grass cover) and A3 (straw cover). The effects of these treatments on soil hydrothermal conditions, growth indices and fruit yield and quality of Annona s1uamosa were systematically monitored and analyzed, and the relationships between these treatments and yield and quality was analyzed based on a Mantel test. The results showed that T5 (W2F2A3) had the highest average soil moisture content over two years, followed by T7 (W3F1A3). The T7 (W3F1A3) treatment effectively reduced soil temperature by 5 °C compared to T1 (W1F1A1). T5 (W2F2A3) had the highest average yield over two years, with an increase of 33.99% compared to T1 (W1F1A1). Additionally, T5 (W2F2A3) has the highest average soluble solids, soluble sugars and vitamin C content over two years, with increases of 28.13%, 13.36% and 4.86%, respectively, compared to T1 (W1F1A1). A Pearson correlation analysis showed that there was a significant correlation between Annona squamosa growth and soil moisture content and soil temperature, and the Mantel test showed that soil hydrothermal conditions had significant influence on the growth and yield. T5 (W2F2A3) has the highest comprehensive benefit in promoting growth, increasing yield and improving quality for the plant. The effects of different irrigation quantities, fertilizer amounts and different cover measures on the coupling interaction for soil hydrothermal status in the root zone, growth, yield and quality of Annona squamosa were investigated, providing reliable theoretical support for the scientific planting model of Annona squamosa in the low-heat river valley of Yunnan Province.

Soil moisture dynamics and associated rainfall-runoff processes under different land uses and land covers in a humid mountainous watershed

Identifying soil moisture dynamics is critical for understanding watershed hydrological processes. Soil moisture responses to rainfall vary with land use and land covers (LULCs) and thus influence rainfall-runoff processes, however, the knowledge about how different LULCs affect such processes was less revealed, especially in humid areas. In this study, we investigated the characteristics of soil moisture content (SMC) and rainfall-related soil moisture responses under four typical LULCs, i.e., waxberry forest, farmland, sloping farmland, and bamboo forest, based on in-situ observations in a humid mountainous watershed. We then used the HYDRUS-1D model to analyze the patterns of the rainfall-infiltration processes and quantified corresponding runoff generation to reveal the partitioning between infiltration and runoff at the event scale. We found significant differences of the average SMC at multiple depths for four LULCs. The deep soil (80 cm) had the largest SMC for the waxberry forest, farmland, and sloping farmland, while the surface soil (10 cm) was the wettest soil layer for the bamboo forest. During the representative rainstorms, although soil moisture responses exhibited depth gradients, the earlier responses at some deep layers indicated the occurrence of preferential flow. Generally, the cumulative infiltration increased while the infiltration rate decreased with the rainfall grade. Farmland and bamboo forest showed the most and the least infiltration, respectively. These results suggested that both the rainfall properties and LULCs had a strong impact on the soil moisture responses. Meanwhile, the estimated average runoff coefficients of four typical LULCs increased with rainfall grade, and the sloping farmland generated the most runoff during the representative rainfall events. Our findings provide new insights into soil moisture dynamics and infiltration regimes under different LULCs in humid areas, which can contribute to hydrological modeling at the field-scale and regional water resource management.

The Effects of Different Rotations of Beans, Maize, and Cabbage on Soil Moisture and Economic Benefits

The article investigates the effects of different cropping rotations on soil moisture and economic benefit. Cabbage–maize–cabbage (CMC), beans–maize–cabbage (BMC), and cabbage–cabbage–cabbage (CCC) treatments were set up to study the effects of different crop rotation combinations on soil water storage, evapotranspiration (ET), water use efficiency (WUE), and economic benefit. The results showed that the average soil moisture content decreased initially and then increased with crop rotation, whereas it continued to decrease with continuous cabbage cropping as the crop grew. CMC reduced ET, whereas BMC increased ET from the nodulation to maturation stages of cabbage compared with CCC in the third experimental year. WUE of different crops showed that cabbage > maize > beans. The economic benefit of the CMC was higher than the other treatments in the third planting year. Therefore, the best crop rotation combination in this area is cabbage–maize–cabbage.

Impact of soil and water conservation structures on the spatial variability of topsoil moisture content and crop productivity in semi-arid Ethiopia

Plant available soil moisture and its spatial variability is among the most important limiting factors for crop and livestock productivity in semi-arid Ethiopia. The objectives of this study were therefore: 1) to measure the effects of land use and slope gradient on spatial variability of topsoil moisture content. 2) to analyze the variability of topsoil moisture content and crop responses under different soil and water conservation (SWC) structures and 3) to analyze whether topsoil moisture content, grain and biomass yields vary in relation to SWC structures. In total, 21 large runoff plots (600–1000 m2) were installed and treated with stone bunds, trenches, stone bunds with trenches and a control plot at each site. Plot sites were located on gentle (5%), medium (12%) and steep (16%) slopes of cropland and rangeland. Topsoil (0–15 cm) moisture content for plots were monitored daily using soil moisture probes (Theta-Probes) and weekly using manual sampling over two growing seasons. Crop performance was monitored during two growing seasons and grain and biomass yield were measured at harvest. Results show that average gravimetric moisture content of the topsoil during growing seasons is remarkably higher for cropland (33–25 g/100 g) compared to rangelands (24–20 g/100 g). This is due to tillage-induced runoff retention and infiltration. Soil moisture content decreases with increasing slope gradients, owing to increased drainage. Considering the effects of SWC structures, average topsoil moisture contents at accumulation and erosion zones are generally higher as compared to middle zone between two successive SWC structures. Average seasonal volumetric soil moisture content of 38.2 (cm3/100 cm3) in 2011 and 39.4 (cm3/100 cm3) in 2012 for accumulation zone of plots with stone bunds with trenchers are significantly higher than at other sampling locations. Crop growth performance, grain and biomass yield varied among plots and depended on slope gradients and SWC structures. Grain yields of wheat in 2011 and barley in 2012 were significantly higher for plots with SWC structures as compared to control plots and are highly correlated to topsoil moisture content (r = 0.64; p < 0.04 in 2011 and r = 0.59, p < 0.01 in 2012). Even when taking into account the cropland area occupied by SWC structures, grain yield increased by (4.2%−33%) for plots with SWC structures as compared to control plots. Overall, our results show that implemented measures may not only reduce runoff and soil loss, but also increase crop productivity by enhancing soil moisture and thus can significantly contribute to sustainability of agro-ecosystems in semi-arid environments.

Effect of drought stress on the physiology and early growth of seven Senegalia (Acacia) Senegal (L.) Britton provenances

Decline of Senegalia senegal (Acacia senegal) in its natural range has been observed and attributed mainly to harsh environmental conditions such as frequent drought occurrences. The objective of this study is to assess the effect of water stress on growth, biomass allocation and photosynthetic capacity in Senegalia senegal seedlings. Seeds were collected from seven provenances in Senegal and grown under greenhouse conditions in a randomized complete block design with 5 replications. Seedlings were subjected to three cyclic droughts by watering them when average soil moisture content dropped to 4.7%, 2.7%, and 2.1% during the first, second, and third dry down cycles, respectively. With the exception of net photosynthetic rate, stomatal conductance and transpiration at the second and third dry down cycles, no drought by provenance interaction was found for any trait measured. Ngane provenance had a lower root/shoot ratio and allometric analysis revealed that Ngane allocated less biomass to roots than shoots. Ngane developed superior growth traits and biomass production, despite similar net photosynthetic rate with other provenances before treatments started. Overall, drought stress significantly reduced biomass, stem height, diameter and leaf gas exchange. Total biomass was reduced by 28.5%, whereas root/shoot ratio was increased by 25% compared to control. Significant interaction on leaf gas exchanges at the second and third dry down cycles reveals different sensitivity levels to drought among provenances with the Ranerou provenance exhibiting no decline in leaf gas exchange. No significant difference of stomatal limitation among genotypes was found, which is indicative of the complex process of photosynthesis and the need for extended times scales for measurements to better depict physiological sensitivity of Senegalia senegal to drought.

Effects of irrigation and nitrogen application on soil water and nitrogen distribution and water-nitrogen utilization of wolfberry in the Yellow River Irrigation Region of Gansu Province, China.

To address the problems of extensive field management, low productivity, and inefficient water and fertilizer utilization in wolfberry (Lycium barbarum L.) production, an appropriate water and nitrogen regulation model was explored to promote the healthy and sustainable development of the wolfberry industry. Based on a field experiment conducted from 2021 to 2022, this study compared and analyzed the effects of four irrigation levels [75%-85% θf (W0, full irrigation), 65%-75% θf (W1, slight water deficit), 55%-65% θf (W2, moderate water deficit), and 45%-55% θf (W3, severe water deficit)] and four nitrogen application levels [0 kg·ha-1 (N0, no nitrogen application), 150 kg·ha-1 (N1, low nitrogen application), 300 kg·ha-1 (N2, medium nitrogen application), and 450 kg·ha-1 (N3, high nitrogen application)] on soil water distribution, soil nitrate nitrogen (NO3 --N) migration, yield, and water-nitrogen use efficiency of wolfberry. The soil moisture content of the 40-80 cm soil layer was higher than those of 0-40cm and 80-120cm soil layer. The average soil moisture content followed the order of W0 > W1 > W2 > W3 and N3 > N2 > N1 > N0. The NO3 --N content in the 0-80 cm soil layer was more sensitive to water and nitrogen regulation, and the cumulative amount of NO3 --N in the soil followed the order of W0 > W1> W2 > W3 and N3 > N2 > N1 > N0 during the vegetative growth period. There was no evidently change in soil NO3 --N accumulation between different treatments during the autumn fruit. The yield of wolfberry under the W1N2 treatment was the highest (2623.09 kg·ha-1), which was 18.04% higher than that under the W0N3 treatment. The average water consumption during each growth period of wolfberry was the highest during the full flowering period, followed by the vegetative growth and full fruit periods, and the lowest during the autumn fruit period. The water use efficiency reached a peak value of 6.83 kg·ha-1·mm-1 under the W1N2 treatment. The nitrogen uptake of fruit and nitrogen fertilizer recovery efficiency of fruit first increased and then decreased with increasing irrigation and nitrogen application. The treatment of W1N2 obtained the highest nitrogen uptake of fruit and nitrogen recovery efficiency of fruit, which were 63.56 kg·ha-1 and 8.17%, respectively. Regression analysis showed that the yield and water-nitrogen use efficiency of wolfberry improved when the irrigation amount ranged from 315.4 to 374.3mm, combined with nitrogen application amounts of 300.0 to 308.3 kg·ha-1. Additionally, the soil NO3 --N residue was reduced, making it an optimal water and nitrogen management model for wolfberry planting. The present findings contribute novel insights into the production of wolfberry with saving water and reducing nitrogen, which helps to improve the level of wolfberry productivity in the Yellow River irrigation region of Gansu Province and other areas with similar climate.

Evaluating the soil hydraulic functions of vegetation restoration in a subtropical hilly catchment: Insights from continuous soil moisture monitoring

The global trend of vegetation “greening” in the context of ecological restoration necessitates an urgent assessment of ecosystem services. As essential components of ecosystem services, the hydraulic functions of soil in infiltrating and retaining water following vegetation restoration remain unclear, especially in subtropical mountainous and hilly areas with complex topographies. From 2018 to 2021, soil moisture data collected at five-minute intervals were monitored for three restoration strategies in a hilly catchment of China’s Three Gorges Reservoir area. The restoration strategies included planted forest (PF) and natural restoration (naturally regenerated forest, NF; deforested pasture, DP). The soil moisture response to rainfall under these strategies was evaluated using several metrics, including the time difference between peak rainfall intensity and peak soil moisture response (Tp2p), cumulative infiltration, and occurrence frequency of preferential flow (PRF). The results showed that the average soil moisture content (SMC) of PF was significantly (p < 0.05) lower than that of NF and DP in both dry and wet seasons, regardless of upslope or downslope location. However, the topographic position affected the difference in average SMC between DP and NF. At the downslope location, the average SMC of DP (0.39 cm3 cm−3) was significantly higher than that of NF (0.33 cm3 cm−3). Conversely, at the upslope location, the average SMC of DP (0.27 cm3 cm−3) was lower than that of NF (0.30 cm3 cm−3). These findings suggested that PF had a lower amount of soil water storage than NF and DP, which was supported by the lowest cumulative infiltration in PF during storm events. The response of soil moisture to storms in PF (Tp2p = 3.1 h) was slower than that in NF (Tp2p = 1.9 h) and DP (Tp2p = 2.5 h). This was consistent with the lower occurrence frequency of preferential flow in PF (PRF = 19.2 %) than NF (PRF = 39.2 %) and DP (PRF = 32.9 %). Therefore, longer response time and less preferential flow indicated that the PF had a relatively poor soil moisture responsiveness to storm events. Accordingly, this study highlights the insufficiency of afforestation in soil water infiltration and retention compared to natural restoration, meriting consideration when assessing soil hydraulic functions in vegetation restoration areas.

Effect of sufficient and deficit irrigation with different salt inputs on the yield of cucumber

Soil salinisation is considered one of the major environmental hazards threatening agricultural productivity and can be accentuated by climate change as well as the use of low-quality water in irrigation. This is the case in our study area which is affected by secondary salinisation due to the use of saline irrigation water for horticultural production. Deficit irrigation technique is implemented especially in arid and semiarid regions due to its potential to optimise water productivity while maintaining or increasing crop yield. The main objective of this study was to compare the effect of irrigation with sufficient (SD) and deficit (DD) doses. This research was carried out in Karcag in 2020. Cucumber was grown on a meadow chernozem soil and was irrigated with SD and DD of two irrigation water qualities. Soil moisture was monitored and crop yields were recorded. Despite the differences in quality and quantity of water, the application of less water by DD maintained the same yield as SD. We found a non-significant difference between the average soil moisture contents under the treatments (15.5 v/v% for SD and 13.5 v/v% for DD). Deficit irrigation can be an efficient technique due to its potential for improving water use efficiency, maintaining sufficient soil moisture content favourable for proper crop development and yield.

Multi-year vertical and life cycle impacts of C-N management on soil moisture regimes

Understanding the long-term impact of C-N management practices on soil moisture content (SMC) is crucial for sustainable agriculture, particularly in mitigating seasonal droughts and storm rainfall constraints. A multi-year (2014–2018) field experiment was conducted, with high-frequency measurements and consideration of a full life cycle, as well as multiple vertical layers (0–100 cm, with intervals of 20 cm). Treatments were arranged in a split plot design with nitrogen (N) fertilizer input (N80% and N60%) as the whole-plot factor, and Carbon (C) treatments (Corg=organic fertilizer, Cstraw=straw mulching and full returning, Cinteg= Corg + Cstraw) were considered as the split-plot factor. The results demonstrated the Cinteg treatment resulted in the highest increase in the five-year averaged SMC (approximately 6.60% greater than Corg), followed by the Cstraw treatment. Additionally, the N60% treatment resulted in significantly higher SMC compared to the N80% treatment, with a range of 1.71–4.12% increase across the life cycle. Furthermore, the research revealed that the average SMC increased the most during the jointing-heading period and the least during the heading-maturity period across all treatments. The vertical results indicated a higher efficiency in water retention within the shallow layers (0–20 cm, 20–40 cm) compared to the deeper layers (80–100 cm) for all treatments. The study recommends adopting integrated C-N management practices, considering life cycle periods and vertical layers, to optimize soil moisture content. It offers valuable insights for optimizing soil moisture management strategies, alleviating seasonal droughts, enhancing water-use efficiency, and fostering sustainable agricultural practices.

Exploring deficit irrigation as a water conservation strategy: Insights from field experiments and model simulation

Deficit irrigation has emerged as a viable approach to increase agricultural water productivity. The objectives of this study were to 1) develop water conservation strategies by investigating responses of green bean (Phaseolus vulgaris) and sweet corn (Zea mays var. saccharata) to four irrigation treatments and 2) evaluate the performance of the Decision Support System for Agrotechnology Transfer (DSSAT) model in simulating growth and yield responses of green bean and sweet corn under four irrigation treatments. A field experiment was conducted using 32 experimental plots, established under a linear move sprinkler irrigation system equipped with variable rate irrigation (VRI) technology, at the Tropical Research and Education Center (TREC), Homestead for two cropping seasons between November and March in 2020–2021 and 2021–2022. The experiment involved four irrigation treatments: full irrigation (FI) (T4), and three levels of deficit irrigation, 75% FI (T3), 50% FI (T2), and 25% FI (T1) with four replications arranged in a completely randomized block design (RCBD) for each crop. The average soil moisture content of the full irrigation treatments was maintained above the management allowable depletion (MAD). Field data collection included various parameters of the crops including plant phenology, plant height, canopy width, fresh and dry biomass, and yield. Results confirmed that all three deficit irrigation treatments did not significantly affect the yield and yield components of the two crops during both seasons compared to the T4. This finding revealed that the highest crop water productivity was achieved from T1, 38.3 and 41.4 kg m−3 for green bean and 54 and 53 kg m−3 for sweet corn during the 2020–2021 and 2021–2022 seasons and up to 75% irrigation water saving could be achieved without affecting plant growth and yield. The DSSAT model performed well in simulating yield and yield components for the two crops in response to the four irrigation treatments. Model evaluation results showed that the minimum mean absolute error (MAE) for green bean fresh pod yield simulation was 2.1 Mg ha−1 with an index of agreement (d-Stat) of 0.6, while for biomass, it was 0.24 Mg ha−1 with a d-Stat of 1. Similarly, for sweet corn, the model simulated fresh cob yield with a minimum MAE of 6.51 Mg ha−1 and d-Stat of 0.9 and biomass with MAE of 1.63 Mg ha−1 and d-Stat of 0.9. Overall, implementing deficit irrigation in green bean and sweet corn fields could result in considerable water savings while achieving acceptable crop yield. The DSSAT model could be also a useful tool to simulate green bean and sweet corn responses to different irrigation scenarios and aid water management decisions under South Florida conditions.

Optimizing Soil Moisture Conservation and Temperature Regulation in Rainfed Jujube Orchards of China’s Loess Hilly Areas Using Straw and Branch Mulching

The implementation of the “Returning Farmland to Forest” project in the loess hilly region of China has led to the establishment of large-scale economic forests, which have become the dominant industry driving local economic development. However, the region faces challenges such as drought, water shortages, and an uneven distribution of precipitation, which have a severe impact on the growth of economic forests, including jujube trees. Water stress significantly reduces yield and efficiency, posing a threat to the sustainable and healthy development of jujube ecological and economic forests. Therefore, this study aimed to address these issues by implementing straw mulching (SM) and jujube branch mulching (BM) measures in the mountainous jujube economic forests. Through long-term monitoring and statistical analysis, the study investigated the effects of different mulching treatments on soil moisture and soil temperature. The research findings reveal that both SM and BM significantly increased soil moisture in the 0–280 cm soil layer during the jujube growing season (p &lt; 0.05). In both normal precipitation (2014) and drought (2015) years, SM increased average soil moisture content by 5.10% and 4.60%, respectively, compared to the uncovered treatment (CK). SM also had a positive impact on the soil moisture content in each layer of the soil profile. However, BM only increased soil moisture content in the 40–100 cm and 220–280 cm soil layers. Additionally, SM and BM reduced the variation of soil moisture, with SM showing a more significant effect in regulating soil moisture and achieving more stable moisture levels. During the jujube growing seasons in 2014 and 2015, SM and BM decreased soil temperature in the 0–10 cm soil layer. The temperature difference compared to CK decreased with increasing soil depth. SM had an overcooling effect, while BM reduced the temperature before the fruit expansion period and maintained warmth afterward. Both SM and BM also reduced the daily range and variation range of soil temperature, with SM having a more pronounced effect. The temperature of the 0–20 cm soil layer exhibited the strongest correlation with air temperature, and SM showed the weakest response. In conclusion, adopting straw mulching and jujube branch mulching in rain-fed jujube orchards in the loess hilly region not only saves materials and reduces costs but also contributes to water retention and temperature regulation. Straw mulching, in particular, plays a more significant role in moisture retention and temperature regulation and is advantageous for soil management in rain-fed jujube orchards. These research findings provide a scientific basis for optimizing water and heat management in orchards with limited water resources.

A Physically Based Model for the Sequential Evolution Analysis of Rainfall‐Induced Shallow Landslides in a Catchment

AbstractPredicting the occurrence time, volume, distribution and run‐out length of shallow landslides is critical for assessing the volume of debris flow in a catchment. Recent studies suggest that the landslides hydro‐mechanical triggering (LHT) model based on threshold‐based mechanical interactions can adequately predict rainfall‐induced landslides. However, this model assumes that the soil‐rock interface is the only sliding surface and cannot dynamically determine a sliding surface above the soil‐rock interface. Therefore, by calculating the wetting front depth in the shallow soil layer and using the limit analysis method, the most likely sliding surface can be dynamically calculated to improve the model. Through linking the Soil and Water Assessment Tool (SWAT, USDA) model and the depth‐resolved LHT model (D‐LHT), a framework for predicting shallow landslides in a catchment was proposed in this work. This framework considers the effects of antecedent rainfall, the mechanical reinforcement of roots, and the spatial distribution of soil properties on slopes. The D‐LHT model was applied to the Jiangjia gully in Yunnan, China, to adequately predicted the occurrence time, scale and spatial distribution of shallow landslides. In addition, the present and antecedent rainfall effects on the shallow landslide volume were analyzed. The results showed that the average soil moisture content threshold was determined by antecedent and same‐day rainfall, which affect the timing and volume of the shallow landslides. This study provides a new method for predicting shallow landslides. The stability and simplicity of the model make it suitable for early warning systems.

Design and development of hydraulic controlled tractor front mounted twin conveyor onion (Allium cepa) digger

In India and many developing countries harvesting of onion (Allium cepa L.) crop is done manually which is cumbersome and time-consuming. The tractor-operated front-mounted twin conveyor onion digger was designed and developed during 2019 in Divisional Workshop (Farm Machinery and Power Engineering) at Govind Ballabh Pant University of Agriculture and Technology, Pantnagar, Uttarakhand. It had five blades made of mild steel (320 mm × 150 mm × 12 mm size) bolted to the base plate instead of one single share to strengthen the share. Onion and soil were separated over conveying unit. Power from the rear PTO (Power take-off) of a tractor to the front-mounted digging unit was conveyed through a power transmission unit which consisted of a gear reduction unit, V-belt and pulley arrangement, and 40 mm diameter of the propeller shaft. The lifting, lowering, and depth were controlled with the help of two single-acting hydraulic cylinders. The biometric and physical properties of onion bulbs (Agri found light red) were found average with equatorial and polar diameter, plant height, neck thickness, and weight of onion dry leaves as 36.19 and 37.19 mm, 284.05 mm, 6.80 mm and 30.19 g respectively. The average soil cone index, moisture content, and bulk density (before transplanting and harvesting) of soil were observed to be 1 kg/cm2, 17.22,12.58%, and 1.50, 1.38 g/cm3 respectively. The performance evaluation in the field found a maximum percentage of exposed and minimum damaged bulbs as 82.55% and 13.51% respectively, at a forwarding speed of 1.5 kmph and conveyor speed of 2 kmph. The field efficiency of the machine was 87.46%.

Multilayer Model in Soil Moisture Content Retrieval Using GNSS Interferometric Reflectometry.

The global navigation satellite system-interferometric reflectometry (GNSS-IR) was developed more than a decade ago to monitor soil moisture content (SMC); a system that is essentially finished has emerged. The standard GNSS-IR model typically considers soil to be a single layer of medium and measures the average SMC between 1 and 10 cm below the soil surface. The majority of the SMC is not distributed uniformly along the longitudinal axis. This study is based on a simulation platform and suggests a SMC-stratified measurement model that can be used to recover the SMC at different depths in the sink and reverse osmosis to address the issue that conventional techniques cannot accurately measure soil moisture at different depths. The soil moisture of each layer was assessed by utilizing the GNSS signals reflected by various soil layers, and this study employed total transmission when the vertical linearly polarized component of the electromagnetic wave was conveyed by the GNSS signal reflected by the soil. This work employed the Hilbert transform to obtain the interference signal envelope, which increases the visibility of the interference signal's "notch" and reduces the burr impact of the interference signal brought on by ambient noise. The accuracy of the SMC measurement at the bottom declines due to the soil's attenuation of the GNSS signal power, but the correlation between the predetermined value and SMC retrieved by the GNSS-IR multilayer SMC measurement model similarly approached 0.92.

Cooling and wetting of soil decelerated ground freezing–thawing processes of the active layer in Xing'an permafrost regions in Northeast China

The accelerated or decelerated freezing–thawing processes of the active layer in Xing'an permafrost regions are crucial for the protection of permafrost. To better understand the freezing–thawing processes of the active layer and its driving factors, according to the observation from 2017 to 2020 of soil temperature and water content in the active layer of forest and peatland in two representative hemiboreal ecosystems in the Da Xing'anling Mountains, Northeast China, the study explored in detail the effects of climatic conditions and local factors on the hydrothermal and freezing–thawing processes of active layer soils. The results showed that during the freezing–thawing cycles of 2017–2020, freezing and thawing start times in the peatland and forest ecosystems soils were generally delayed, and it took longer for the active layer soil to completely thaw than to freeze. The annual average soil temperature in the peatland's active layer (5–80 cm) was 0.7–2.0 °C lower than that in the forest, and the annual average soil moisture content on the peatland was 5.5%–26.7% higher than that in the forest. Compared with the forest ecosystem soils, the ground surface freezing time of the peatland was delayed by 3–10 d, and the freezing rate decreased by 1.1–1.5 cm d−1, while the beginning time of thawing was advanced by 22–27 d, and the thawing rate decreased by 1.3–1.4 cm d−1. In the process of decreasing soil temperature and increasing soil moisture content, the freezing and thawing rate of the active layer would be reduced, decelerating the freezing–thawing processes of the active layer in the process of decreasing soil temperature and increasing soil moisture content. The results provide the key original data for studying the formation and evolution of active layer and permafrost in the Xing'an permafrost regions in Northeast China and can be used to validate the prediction of ecosystem succession under the combined influences of climate change and permafrost degradation.

ОПРЕДЕЛЕНИЕ ПОЛИВНОЙ НОРМЫ ДЛЯ ФОРМИРОВАНИЯ ПЕРВИЧНОГО ЛОКАЛЬНОГО КОНТУРА КАПЕЛЬНО-УВЛАЖНЕННОЙ ПОЧВЫ

Purpose: development of methodology for determining the irrigation rate value, which ensures the formation of a primary local contour of moistened soil in the soil space under drip irrigation with one emitter. Materials and methods. The methodological and factual basis of the development were materials and empirical dependencies obtained from the data of author's field studies of local moisture contours formed under various soil conditions with above-surface and surface drip irrigation. Results and discussion. The analysis and evaluation of known approaches to the calculation of irrigation rates for drip irrigation of plants is carried out, the direction of the development of the methodology is determined. Based on materials of field and office studies, 11 contour profiles of drip-moistened soil formed under various soil and technological conditions of drip irrigation were obtained. Soil conditions are characterized by a wide range of changes in their parameters: the content of physical clay is from 20.8 to 74.6 % of the dry soil mass (DSM), the lowest moisture capacity is from 16.9 to 32.2 % of DSM, the level of additional irrigation moisture is from 60 to 70 % of the lowest moisture capacity. Moisture contours were formed with an average soil moisture content of 90 % of the lowest moisture capacity. Empirical dependencies for determining the maximum and average radius (diameter) of moisture contours at given depths of the moistened soil layer, which make it possible to predict the volumes of moisture contours are obtained. The dependence and a method for calculating the irrigation rate value, which ensures the formation of a moisture contour of a given depth and a given level of soil moisture, are obtained for a wide range of granulometric and water-physical characteristics of soils. Conclusion. A method for calculating the irrigation rate required for the formation of a local moisture contour in soil space with specified dimensional and moisture parameters during irrigation water delivery by one drip micro emitter is proposed.

Effects of Living Mulch and Branches Mulching on Soil Moisture, Temperature and Growth of Rain-Fed Jujube Trees.

The influence of different mulching measures on soil moisture, soil temperature, and crop growth was investigated during the jujube growing season in rain-fed jujube orchards using micro-plot experiments. The mulching treatments included clean tillage (CT, control treatment), jujube branches mulching (JBM), and white clover planting (WCP). The results revealed that: (1) The average soil moisture content of JBM was greater than that of CT by 3.76% and 2.34%, respectively, during the 2013 and 2014 jujube growth periods, and its soil water deficit was minimal in each soil layer from 0 to 70 cm. WCP had the greatest soil water deficit. The average soil moisture content of the 0–70 cm soil layer in WCP was 3.88% and 5.55% lower than that in CT during the 2013 and 2014 jujube growth seasons, respectively (p < 0.05). (2) JBM had the highest annual average soil moisture content in each soil layer from 0 to 70 cm, followed by CT, while WCP had the lowest. White clover and jujube competed for water in the 20–40 cm soil layer, and JBM had the lowest variation in soil moisture. (3) Mulching with jujube branches and planting white clover could both control the temperature of the 0–25 cm soil layer and narrow the daily temperature range, with JBM being the least affected by air temperature. (4) Jujube’s leaf area index and stem diameter increase in JBM were both significantly greater than in CT and WCP. In conclusion, using pruned jujube branches as surface mulch is appropriate for rain-fed jujube orchards because it can preserve soil moisture, regulate soil temperature, and promote jujube growth.

Afforestation changes the trade-off between soil moisture and plant species diversity in different vegetation zones on the Loess Plateau

Soil moisture and plant species diversity are key factors determining the structure, function and stability of terrestrial ecosystems in arid and semiarid environments. However, the relationship between species diversity and soil moisture of different vegetation restoration measures over a precipitation gradient has not been thoroughly explored, inhibiting decision-makers’ ability to formulate vegetation restoration policies. In this study, we examined the relationship between the soil moisture content (SMC) and species diversity of two vegetation restoration measures (afforested lands and natural restoration grassland) in different vegetation zones (steppe, forest-steppe and forest) on the Loess Plateau. The results showed that the species diversity of afforested lands was ranked as forest zone < forest-steppe zone < steppe zone, which contrasts with natural grasslands. The average SMC of afforested lands was ranked as steppe zone < forest-steppe zone < forest zone, and the results further indicated afforestation decreased SMC compared with the natural grassland. The relative benefit of the species diversity index in afforested land was more extensive than that of soil moisture in the steppe zone but smaller in the forest zone, and the trade-offs between soil moisture and species diversity were smallest in the forest-steppe zone but approached no trade-offs in natural grasslands. Our study suggests that although natural grassland is the ideal ecosystem across all the vegetation zones examined, the forest and forest-steppe zones are most suitable for afforestation, accounting for the human need for timber harvesting. However, afforestation plantations need to be thinned appropriately to maintain high soil moisture and species diversity and low trade-offs between soil moisture and species diversity.

Soil Pollution Assessment of a Gas Flare Site in the Niger Delta Region

Aim: The aim of this research was to investigate the level of pollutants deposition on soil generated from a gas flaring site.&#x0D; Study Design: The Soil Samples for this study were picked from two sets of locations (a proposed gas flare site situated at Ogbogu Gas plant and two control sites sfrom a primary source of local farm lands). A total number of eighteen samples were collected from the five different sampling spots as designated using the global positioning system (GPs).&#x0D; A contaminated Site and three farm lands within Ogbogu and Ebocha community were mapped at 20m, 50m, 100m, 500m &amp; 700m from the gas flare site and mapped with GPs location at two different sampling depths (0-15 &amp; 15-30) cm.&#x0D; A Control Site and two (2) farm lands within Idu Ekpeye community were mapped outside the area of concentration from the gas flare sites. These locations were chosen to determine by comparative assessment, the impact of gas flaring on the soil properties of the contaminated sites.&#x0D; Place and Duration of Study: This study was carried out in Ogba/Egbema/Ndoni Local Government Area of Rivers State. This area was chosen for this study because of the high volume of petroleum activities. Oil and gas processing, production, transportation and utilization for power generation occur daily in the area resulting in numerous cases of environmental degradation and pollution.&#x0D; Methodology: This research explores and presents a method of analysing the environmental impact of gas flaring in the Niger Delta so as to provide the data required for the complete analysis and evaluation of the various observed and noted health and environmental effects of gas flaring in Niger Delta. Different samples at various proximities at 200m, 500m, 1000m, 5000m and 7000m from the flare site using a hand aguar equipment sampled at depths of (0-15)cm and (15–30)cm were taken and measurements and experimentations were meticulously carried out.&#x0D; Results: The results obtained in this research show a marked trend as all the parameters considered indicated a gradient away from the flare points in all the flow stations such as soil pH changing from acidic (4.0-4.2) to near neutral (6.4-6.6) away from the flare points and the average low soil moisture content of (17% - 23%) as against 40% for the (10m and 20m) and control distance. The quantity of carbon emitted by these flares are about 2,525,000.00 tonnes of carbon per day. These values portray a bad omen for the affected communities.&#x0D; Conclusion: Contamination of agricultural soils by trace metals creates a serious risk of the introduction of these xenobiotics into human food chain. The soil fertility is being reduced as this study has revealed an increase in temperature along-side an increase in gas flaring and flare distances.&#x0D; This study recommends that gas flaring should be seen as a violent action against the people and that the flared gas should be channelled to meeting the ever increasing demand for energy in the industrial sector of the economy.

Field-scale compression of Sphagnum moss to improve water retention in a restored bog

The restoration and subsequent regeneration of Sphagnum moss on harvested peatlands can result in poor hydrological connectivity between the regenerated Sphagnum moss and the remnant cutover peat due to the formation of a capillary barrier that favours retention of water in the underlying cutover peat. In a restored cutover peatland in Québec, Canada, this resulted in a lower soil water content of the regenerated Sphagnum moss compared to a natural analogue, which may limit carbon sequestration potential. Previous work has shown it may take > 40 years for the regenerated moss layer to overcome this capillary barrier effect, however mechanical compression may provide a novel restoration technique to weaken the capillary barrier in restored peatlands. This study evaluated the effectiveness of field-based mechanical compression to ameliorate the capillary barrier effect and increase the moisture content in a restored cutover peatland. A section of restored Bois-des-Bel peatland was compressed using a John Deere 6430 series tractor in January 2016, followed by hydrological monitoring May-August. The Compressed site was compared to a nearby Uncompressed site, and a natural peatland ∼ 2 km away, to determine relative success of mechanical compression. The compression reduced moss height by 48%, increasing bulk density by 37% and reducing the proportion of macropores by 15% throughout the moss layer. Consequently, compression increased soil water retention and average soil moisture content at the Compressed site was consistently higher throughout the moss profile than in the Uncompressed site. This increased the resilience of the moss to drying, though the degree of increased resilience is unknown. Despite not having the same hydrophysical properties of the Natural site, the Compressed site was wetter than the Uncompressed site due to the lessening of the capillary barrier effect and moving the surface closer to the water table, thus decreasing the water stress of the regenerated Sphagnum carpet.