Increased Soil Moisture Research Articles

Tillage Effects on Soil Moisture and Sulfur use Efficiency by Sesame (Sesamum indicum L.) on Vertisol of North Ethiopia

Sesame, produced in Humera is among the highest quality seeds grown in Ethiopia and even in the world. However, its productivity is by far less than the production potential due to nutrient depletion, moisture stress and lack of crop response to applied fertilizer. An experiment was conducted to evaluate the effects of tillage practices and sulfur fertilizer rates on moisture conservation and agronomic sulfur use efficiency of sesame crop in 2015. The treatments were tied ridges (M1) and flatbed tillage practices combined with five rates of sulfur fertilizer at a split plot design with three replications. M1 and flatbed treatments were assigned to the main plots, while sulfur fertilizer rates were assigned to the sub-plots. Measurements of soil moisture content at 0-20 cm, 20–40 cm and 40–60 cm depth were conducted throughout the growing season at an interval of 13 days using the gravimetric method. The results showed that M1 increased the soil moisture content up to 44% compared to the flatbed. The highest amount of agronomic sulfur use efficiency 14.4 kg kg-1 was also obtained from M1 tillage at 10 kg S ha-1. On the other hand, the highest amount of agronomic sulfur use efficiencies under flatbed tillage was 9.5 kg kg-1 at 10 kg S ha-1. M1 increased agronomic sulfur use efficiency by 51.6%. Tied ridging is the best option to significantly increased soil moisture availability in the root zone and as a consequence it increased agronomic sulfur use efficiency of the sesame. Therefore, in-situ moisture conservation using tillage practices like M1 at farm level should be demonstrated at farmer’s field in the semi-arid Humera areas for improving sulfur fertilizer use efficiency.

Rock Powder Enhances Soil Nutrition and Coffee Quality in Agroforestry Systems

The use of rock powders is an agricultural practice that facilitates the agroecological transition and autonomy of many farmers. These inputs should be used in conjunction with management systems that enhance the weathering of the minerals contained in the rocks. This study aimed to assess the impact of incorporating gneiss powder on soil quality and coffee cultivation within agroecological and organic frameworks, encompassing agroforestry systems (AFSs) as well as areas fully exposed to sunlight (FS). Comprehensive analyses, including chemical, microbiological, and physical assessments, were carried out on the soil. The study involved evaluating various parameters such as electrical conductivity, grain density, total titratable acidity, and pH of the exudates to gauge the coffee quality. Following a 24-month application of rock powder, noteworthy observations included increased soil moisture in agroforestry systems (AFSs), presumably attributable to enhanced nutrient availability (potassium, calcium, magnesium, copper, and zinc) derived from the gneiss powder. In addition, a higher level of CO2 was derived from microbial respiration than from soil production. Similarly, coffee beans presented lower electrical conductivity, higher density, and fewer defects in AFSs than fully exposed sun systems (FS). The total titratable acidity values remain consistent with the limits indicated in the literature for quality coffees; the pH values, however, were lower. The results suggest that the use of gneiss powder enhances soil microorganism activity and accelerates the biological weathering of minerals for coffee plantations in AFSs.

Tillage and Crop Residue Effects on Soil Carbon and Moisture for Wheat (Triticum aestivum L.) Productivity in Semiarid Regions of Tigray, Ethiopia

Soil tillage is one of the basic agriculture operations. However, the appropriate tillage type, tillage time, and tillage frequency for effective moisture harvesting and sustainable soil fertility were not investigated for Tigray. A field experiment was conducted during 2016 to 2018 in Enderta district. It was done with the objective of evaluating the effect of different tillage practices on wheat productivity. The treatments were (I) permanent bed+ crop residue,(II) three times tillage with furrow, (III) two times tillage with furrow, and (IV) farmer’s practice tillage. A randomized complete block design with three replications was set up. Measurement of soil moisture content was conducted using the gravimetric method. Agronomic parameters were collected and analyzed using GenStat. Marginal rate of return was also estimated from the total revenue and total variable cost. Positive effect was found on soil fertility, soil moisture content, and grain yield due to the tillage practice and crop residue. Permanent bed+ crop residues and three tillage furrow increased soil moisture content, organic carbon, and total nitrogen, as well as the yield and yield components at the second and third year of experimentation. The highest grain yield 2952 kg ha-1 and biomass yield 8582 kg ha-1 were recorded at the three tillage furrow in the third year of experimentation. The 59,056 ETB was the highest net revenue recorded at three times tillage with furrows. From this result, it can be concluded that without adding any additional input instead of changing agricultural operation techniques, the economic benefit of farmers’ could be improved by 48%. Therefore, three tillage practices with furrow is the most economically feasible technology for farmers to increase wheat productivity in the semiarid area of Enderta district.

Distribusi Kadar Air Tanah Dengan Irigasi Curah Pada Budidaya Tanaman Stevia (Stevia rebaudiana B.)

Sprinkler irrigation emulates rainfall patterns to supply plant water, improving soil conditions and ensuring sustained field performance. This study investigated the impact of sprinkler irrigation on Stevia's Coefficient of Uniformity (CU), soil moisture level, and crop coefficient (Kc). The experiment was conducted in Karangploso Village, Malang Regency, 700 m above sea level. Stevia plants were cultivated using sprinkler irrigation, and their water requirements were assessed by analyzing changes in soil moisture after irrigation. The results showed that sprinkler irrigation significantly increased soil moisture content. At a depth of 0-20 cm, soil moisture increased by an average of 0.135 cm3/cm3 (water depth of 27 mm), while at depths of 20-40 cm and 40-60 cm, the increase was 0.121 cm3/cm3 (24 mm) and 0.065 cm3/cm3 (13 mm), respectively, with a total water depth of 64 mm for 0-60 cm soil depth of 70 mm irrigation event. The crop coefficient (Kc) of Stevia varied during its growth stage, starting from 0.55 in the first week and gradually increasing to 0.57 in the 6th week. The total water requirement for Stevia until harvest at 60 days reached 279.8 mm. This finding emphasize the importance of monitoring and adjusting irrigation practices to ensure optimal growth of Stevia. Sprinkler irrigation effectively increased soil moisture content and determined the appropriate water requirement and Kc value for Stevia cultivation.

Altered intra-annual precipitation patterns affect the N-limitation status of soil microorganisms in a semiarid alpine grassland

The ongoing intensification of the hydrological cycle due to global climate change alters intra-annual precipitation variability. Changes in precipitation patterns lead to disparities in soil moisture; however, the responses of soil extracellular enzyme activities (EEAs) and microbial metabolism limitations to them is unclear. This study conducted an in situ field experiment in the alpine grasslands of the Kunlun Mountains to simulate the same amount of precipitation but change the distribution time of precipitation within the plant growing season. We examined the effects of variability in intra-annual precipitation patterns on the stoichiometry of topsoil (0–5 and 5–20 cm) properties, microbial biomass, and EEAs. Results showed that altered precipitation patterns significantly increased soil moisture’s disparity index (D) by 57 %–89 %. The activity of nitrogen-acquiring enzymes (L-leucine aminopeptidase) was increased by 20.82–32.08 % (P < 0.05) with increased variability of precipitation, while phosphorus-acquiring enzymes (Acid phosphatase) and carbon-acquiring enzymes (β-glucosidase) both decrease by 9.25–23.35 % and by 17.86–33.04 %, respectively (P < 0.05). We determined that soil microorganisms in the study region were metabolism-limited by nitrogen (vector angles < 45◦), and increased precipitation variability exacerbated nitrogen limitation (decrescent vector angles) and alleviated carbon limitation (shortened vector length). In addition, soil EEAs can be both interactively influenced by biotic and abiotic factors, with abiotic factors (i.e., D, soil organic carbon content, and soil total nitrogen content) having a stronger effect. Our study provides an effective strategy for regulating soil EEAs, microbial biomass, and microbial metabolism limitation and contributes to developing nutrient management and restoration strategies in semiarid alpine grassland ecosystems.

Effects of water management and grassland renewal on the greenhouse gas emissions from intensively used grassland on bog peat

Artificial drainage is prerequisite for conventional agricultural use of peatlands, but causes high emissions of greenhouse gases (GHG), mainly carbon dioxide (CO2). Furthermore, grassland renewal is regularly practiced to maintain high fodder quality, but might cause high emissions of nitrous oxide (N2O). Raising water levels is necessary to reduce CO2 emissions. Water management by subsurface irrigation (SI) and ditch blocking (DB) is thus discussed as potential compromise between maintaining intensive grassland use and reducing GHG emissions. Here, we present results of a four year study on the effects of SI and DB in combination with grassland renewal on GHG emissions from an intensively used grassland on bog peat in North-Western Germany.The water management itself was successful and lead to average mean annual water levels of -0.33 m at the parcels with SI. This was 0.38 m higher than at the control parcels. Ditch blocking also raised the mean water levels to -0.33 m, but the parcel was dryer in summer and wetter in spring than those with SI. Despite clear effects on water levels, CO2 and total GHG emissions were much (38 % and 31 %) higher from SI parcels than from the control parcels. CO2 and GHG emissions of the DB parcel were similar to those of the control. Shallow ploughing increased N2O emissions for around 1.5 years, but there was no clear effect of direct sowing. Methane emission from all parcels were low. The surprising results regarding CO2 might be explained by an interaction of increased soil moisture in the topsoil and improved nutrient retention during periods of high soil temperatures facilitated by SI and, concurrently, by limitations of microbial activity due to dry conditions at the control parcels. Thus, results of this study do not support subsurface irrigation as a GHG mitigation measure at intensively used bog peatlands.

Restoration approach for alpine extremely degraded landscapes: testing direct seeding and mulching with grass clippings

Alpine meadows are key ecosystems that are facing increasing degradation due to climate change and anthropogenic disturbances. Despite tremendous efforts in ecological restoration and diverse communities rebuilding in alpine regions, restoration of extremely degraded alpine meadows (which have lost mattic epipedon) remains a major challenge for land managers. Here, we performed a field restoration experiment that combined seeding three grass species commonly (Elymus nutans, Poa annua, and Festuca sinensis) used in alpine meadow restoration with the application of grass clippings as mulch (bare land without mulching, 50% mulch cover, and 100% mulch cover) to ameliorate the soil surface conditions of degraded bare land. Soils covered with 50% and 100% mulching increased soil moisture, seedling density, plant cover, plant density, aboveground biomass, and belowground biomass, and reduced soil temperature during strong radiation days and insulated at night. In the three grass species seeding plots, mulching with grass clippings also improved seedling density, plant cover, plant density, and biomass. Moreover, 100% mulching had stronger restoration effect than 50% mulching. We further demonstrated that the improvement of surface microclimate in degraded alpine meadows by grass clipping mulching, that is, increasing soil moisture and regulating soil temperature, is an important reason for the success of grassland restoration. Mulching with grass clippings simulates the original mattic epipedon, improving the surface hydrothermal conditions and promoting ecological restoration facilitation. We encourage the application of locally available grass clippings after seeding as this can be an efficient, low‐cost, and sustainable approach for restoring extremely degraded high‐elevation alpine grassland ecosystems.

Drivers of soil microbial and detritivore activity across global grasslands

Covering approximately 40% of land surfaces, grasslands provide critical ecosystem services that rely on soil organisms. However, the global determinants of soil biodiversity and functioning remain underexplored. In this study, we investigate the drivers of soil microbial and detritivore activity in grasslands across a wide range of climatic conditions on five continents. We apply standardized treatments of nutrient addition and herbivore reduction, allowing us to disentangle the regional and local drivers of soil organism activity. We use structural equation modeling to assess the direct and indirect effects of local and regional drivers on soil biological activities. Microbial and detritivore activities are positively correlated across global grasslands. These correlations are shaped more by global climatic factors than by local treatments, with annual precipitation and soil water content explaining the majority of the variation. Nutrient addition tends to reduce microbial activity by enhancing plant growth, while herbivore reduction typically increases microbial and detritivore activity through increased soil moisture. Our findings emphasize soil moisture as a key driver of soil biological activity, highlighting the potential impacts of climate change, altered grazing pressure, and eutrophication on nutrient cycling and decomposition within grassland ecosystems.

Preferential flow in the shallow vadose zone: Effect of rainfall intensity, soil moisture, connectivity, and agricultural management

AbstractPreferential flow is ubiquitous in soils, and it affects water infiltration, runoff, and contaminant transport. Undisturbed soil lysimeters (n = 10; 900 cm2) were collected from an agricultural field to quantify the effect of climate, soil moisture, connectivity, and agricultural practices on water transport through the shallow vadose zone. A series of 10 rainfall simulations was conducted on each lysimeter (n = 100 events) and data were analysed within a framework of five case studies where we assessed the impact of rainfall intensity (n = 30 events), soil moisture (n = 28), and tillage (n = 21). Three lysimeters that had near‐zero flow initially were modified to investigate dynamics of direct surface connectivity through an artificial macropore in which we assessed the impacts of soil moisture (n = 12) and subsequent disruption via tillage (n = 9). Stable water isotopes were used to separate leachate into event (Qe) and pre‐event water (Qpe). Results showed that event water transport in leachate was not affected by rainfall intensity (Qe/Q = 49% ± 21% to 50% ± 24%); however, event water decreased from 65% ± 5% to 23% ± 28% with increasing soil moisture. Lysimeters with artificial macropores resulted in leachate that was nearly all event water (85% ± 12% to 92% ± 4%) irrespective of soil moisture. Tillage decreased event water transport for both lysimeters with and without an artificial macropore by ~30%. Findings show how varying initial and boundary conditions produce a continuum of preferential flow. Water and tracer flux data collected in the current study are therefore essential for predicting conditions with high relevance of preferential flow and contaminant transport when assessing or modelling long‐term hydrographs where these conditions are only met during a small proportion of the flow time.

Breaking Dormancy and Increasing Restoration Success of Native Penstemon Species Using Gibberellic Acid Seed Coatings and U-Shaped Furrows

Many plant species exhibit strong seed dormancy. This attribute benefits the species’ long-term survival but can impede restoration when rapid establishment is required. Soaking seeds in gibberellic acid (GA3) can overcome dormancy and increase germination but this treatment may not be effective outside the laboratory. An easier and potentially more effective method to apply this hormone is to coat seeds with a GA3-impregnated polymer. Seed dormancy can also be mitigated by creating a favorable microsite with increased soil moisture. We compared the emergence and establishment of penstemon seeds coated with GA3 to those of uncoated seeds planted in shallow drill rows versus deep, U-shaped furrows. Overall, 6 times more Palmer’s penstemon (Penstemon palmeri; p &lt; 0.01) and 21 times more thickleaf penstemon (P. pachyphyllus; p &lt; 0.001) established when coated with GA3, but GA3 coating did not affect the establishment of firecracker penstemon (P. eatonii; p = 1). Establishment was higher from deep furrows than shallow rows (p &lt; 0.001). These results indicate that GA3 seed coating and deep, U-shaped furrows may improve the restoration success of some native forbs by breaking dormancy and providing a favorable microsite. Land managers could use these techniques to restore native forbs in dry, disturbed areas.

Simulation-Based Study on the Effect of Green Roofs on Summer Energy Performance in Melbourne

Green roofs are increasingly recognised as a crucial urban solution, addressing climate change, enhancing energy efficiency, and promoting sustainable architecture in densely populated areas. In this manuscript, the research study delves into the influence of green roofs on energy consumption, focusing on the Treasury Place building in Melbourne, Australia. The utilisation of DesignBuilder and EnergyPlus simulations was explored. Various green roof parameters such as the Leaf Area Index (LAI), plant height, soil moisture, and tree coverage were optimised and compared against base case scenarios. The key findings indicate an optimal LAI of 1.08 for maximum energy savings, with diminishing returns beyond an LAI of 2.5. The soil moisture content was most effective, around 50%, while a plant height of approximately 0.33 m optimised energy reduction. The introduction of 50% canopy tree coverage provided temperature regulation, but increased soil moisture due to trees and their influence on wind flow had an adverse energy impact. These results emphasise the necessity for precise green roof representation and parameter optimisation for maximum energy efficiency. This research offers essential insights for those in urban planning and building design, endorsing green roofs as a pivotal solution for sustainable urban environments.

A feasible method of induced biological soil crust propagation through the inoculation of moss and addition of soil amendments in a Pb-Zn tailing pond

The stacking of tailings results in serious environmental pollution and plant growth difficulty. However, moss and microorganisms can successfully colonize in tailings to form biological soil crusts (BSCs) and provide a feasible means to ecologically restore tailing reservoirs. Nonetheless, information on this approach is scarce. In this study, a 90 day field experiment was conducted to form BSCs in a Pb-Zn tailing pond in Jianshui County, China by inoculating in-situ moss crust fragments and adding three soil amendments. Results showed that induced BSCs successfully propagated, and the biomass increased to 15.51–20.33 times the initial value. Moss inoculation considerably increased the soil moisture, water-holding capacity, and phosphatase by 9.2 %, 8.8 %, and 64.0 %, respectively, and decreased exchangeable fraction Pb by 30.7 %. The co-inoculation of moss and biochar remarkably increased soil moisture, water-holding capacity, cation exchange capacity, sucrase, urease, and phosphatase activity by 22.3 %, 23.4 %, 116 %, 80.5 %, 28.6 %, and 240 %, respectively, and decreased the bulk density by 13.3 %. The addition of red soil reduced the total contents of Pb and Zn, whereas that of the stabilizer increased the pH and decreased the bioavailability of Pb and Zn. Co-inoculation greatly increased the biotic community species richness and changed their structure and function. The dominant photosynthetic eukaryotes shifted from Synechococcales to Oscillatoriales. Bacterial nutritional types shifted from chemoautotrophy to photoautotrophy and chemoautotrophy, and fungal nutritional types changed from oligotrophy to copiotrophy. These changes drove alterations in bacterial and fungal community structures. These results indicated that the propagation of induced BSCs can rapidly improve the soil structure and nutrient cycle, restore the biotic abundance and function, and facilitate the soil formation of tailings. Thus, this method holds promise for the ecological restoration of tailings.

Regimes of Soil Moisture–Wet-Bulb Temperature Coupling with Relevance to Moist Heat Stress

Abstract Human heat stress depends jointly on atmospheric temperature and humidity. Wetter soils reduce temperature but also raise humidity, making the collective impact on heat stress unclear. To better understand these interactions, we use ERA5 to examine the coupling between daily average soil moisture and wet-bulb temperature (Tw) and its seasonal and diurnal cycle at global scale. We identify a global soil moisture–Tw coupling pattern with both widespread negative and positive correlations in contrast to the well-established cooling effect of wet soil on dry-bulb temperature. Regions showing positive correlations closely resemble previously identified land–atmosphere coupling hotspots where soil moisture effectively controls surface energy partition. Soil moisture–Tw coupling varies seasonally closely tied to monsoon development, and the positive coupling is slightly stronger and more widespread during nighttime. Local-scale analysis demonstrates a nonlinear structure of soil moisture–Tw coupling with stronger coupling under relatively dry soils. Hot days with high Tw values show wetter-than-normal soil, anomalous high latent and low sensible heat flux from a cooler surface, and a shallower boundary layer. This supports the hypothesis that wetter soil increases Tw by concentrating surface moist enthalpy flux within a shallower boundary layer and reducing free-troposphere-air entrainment. We identify areas of particular interest for future studies on the physical mechanisms of soil moisture–heat stress coupling. Our findings suggest that increasing soil moisture might amplify heat stress over large portions of the world including several densely populated areas. These results also raise questions about the effectiveness of evaporative cooling strategies in ameliorating urban heat stress. Significance Statement The purpose of this study is to provide a global picture of the relationship between soil moisture anomalies and a heat stress metric that includes the joint effects of temperature and humidity. This is important because a better understanding of this relationship will help improve the prediction of extreme heat stress events and inform strategies for ameliorating heat stress. We find a widespread positive correlation between soil moisture and heat stress, in contrast to studies relying on temperature alone. This raises the possibility that, over much of the world, and in the most populous regions, strategies like irrigation or “greening” that can reduce temperature might be ineffective or even harmful in reducing heat stress with humidity incorporated.

Rhizosheath formation depends on mucilage concentration and water content

Abstract Aims Root exudates contain polymers that form crosslinks and can create a jelly like substance known as mucilage, which adheres to soil and thus promotes the formation of rhizosheaths, i.e. soil that remains attached to the roots after gentle shaking. We hypothesized that rhizosheath formation is optimal at an intermediate chia seed mucilage concentration and water content, but that its formation is limited at both a high concentration of chia seed mucilage and under dry conditions as well as at a low concentration of chia seed mucilage and under wet conditions. We used an artificial root soil system in which soil moisture and mucilage concentrations could be varied independently from one another with respect to their effect on rhizosheath formation. Methods Jute cords were disposed in sandy loam soil and in quartz sand. In a subsequent study, they were also amended to different moisture contents with five different concentrations of mucilage (from 0 to 0.2 g dry mucilage g−1 water), before being isolated from chia and flaxseed mucilage after swelling of the respective seeds in distilled water for 15 min. Results We found that in dry soil, rhizosheath formation peaked at an intermediate chia seed mucilage concentration. This behavior was supported by our conceptual model of mucilage spreading and rhizosheath formation, which relies on a radial diffusion equation and assumes that at low mucilage concentration, molecule numbers are insufficient to support polymer-like networks that stick soil particles together. In a very concentrated gel, however, mucilage is too sticky to diffuse far into the soil. Increasing soil moisture promotes rhizosheath formation both in a low and a high mucilage concentration range, although only up to an intermediate volumetric water content of 0.15cm3 cm–3. Conclusions We conclude that both water and chia seed mucilage concentration are important drivers of rhizosheath formation. The effects are not additive but can combine to an optimum range, with a maximum formation of rhizosheaths observed in this study at 0.12 g mucilage g−1 rhizosphere water.

Impact of Mulching on Soil Moisture and Sap Flow Characteristics of Jujube Trees

The main purpose of this study was to assess the influence of grass planting and jujube branch mulching on soil moisture levels and jujube tree transpiration rates, with the ultimate goal of improving jujube tree production in rain-fed orchards. The study encompassed four treatments: jujube branch mulching (JBM), jujube branch mulching with white clover planting (JBM + WCP), white clover planting (WCP), and clean cultivation (CC). During a two-year experiment, it was observed that the JBM treatment exhibited the highest capacity for moisture conservation. Specifically, it resulted in an average increase of 2.69% (in 2013) and 2.23% (in 2014) in soil moisture content compared with the CC treatment. The application of statistical analysis revealed significant differences (p &lt; 0.05) between JBM and JBM + WCP, as well as highly significant differences (p &lt; 0.01) between JBM and WCP in the year 2013. In 2014, JBM exhibited significant differences (p &lt; 0.01) from both JBM + WCP and WCP. Between April and August, JBM exhibited the highest soil moisture content, followed by CC, with WCP showing the lowest levels. From September to October, JBM retained its status as the treatment with the highest soil moisture content, JBM + WCP ranked second, and CC experienced a decline and recorded the lowest soil moisture content. Under sunny conditions, all treatments showed a broad peak curve in the daily variation of sap flow velocity. In cloudy weather, a multi-peak wave-like curve was observed with similar trends across treatments. Between April and August, the monthly average sap flow velocity of JBM ranked the highest, followed by CC, while WCP showed the lowest velocity. During the period of September to October, JBM maintained its lead in sap flow velocity, while JBM + WCP rose to the second position, and CC’s sap flow velocity dropped to the lowest level. JBM and WCP treatments showed significant differences (p &lt; 0.01), and in 2014, JBM also had significant differences (p &lt; 0.05) compared with JBM + WCP. The sap flow velocity was positively correlated with air temperature, vapor pressure deficit, wind velocity, photosynthetically active radiation, and soil temperature. Photosynthetically active radiation was identified as the main driving factor influencing jujube tree transpiration. In conclusion, the findings of this study demonstrate the effectiveness of using pruned jujube branches for coverage in rain-fed jujube orchards. This approach not only conserves mulching materials and diminishes the expenses associated with transporting pruned jujube tree branches away from the jujube orchard but also achieves multiple objectives, including increasing soil moisture, promoting jujube tree transpiration, and enhancing soil water utilization. These results have significant implications for the efficient utilization of rainwater resources in rain-fed jujube orchards and provide valuable insights for practical applications in orchard management.

Participatory design to investigate the effects of farmers’ fertilization practices under unsubmerged conditions toward efficient nutrient uptake in rainfed rice

Rainfed agriculture plays a vital role in providing food and livelihoods globally. However, its production is adversely affected due to uncertainty in rainfall patterns causing unsubmerged conditions during the dry period, which is increasing under the impact of climate change. Given that rice is a primarily grown crop in rainfed conditions and is the staple food of half the global population, it is under pressure to increase production due to the burgeoning population globally. Therefore, proper farming management such as balanced fertilization practices, irrigation etc. are required. Thus, we studied the effect of human-induced nutrient application quantity for nitrogen (N) and phosphorus (P), on production efficiency and assessed the nutrient budget in rainfed rice fields of Jamuna command area, Assam, India. A questionnaire was developed to know the farm management practices adopted by farmers and accordingly, applied N and P doses were ranked. Low, medium, high and very high doses for N are 40–60, 61–80, 81–100, 101 kg ha−1 and above, respectively, while for P are 0–4, 5–9, 10–19, 20 kg ha−1 and above respectively. Rice plants were sampled from farmers’ field of selected thirteen villages, at the maturity stage, soils were sampled after rice harvest to analyze Total Kjeldahl Nitrogen (TKN) and available Phosphorus (Pav). Nitrogen (N) balance was positive ranging from 33 kg ha−1 to 72 kg ha−1. Phosphorus (P) balance was ranging negative from 28 kg ha−1 to 129 kg ha−1. N uptake increased in order of low<medium<very high<high doses while P increased in order of high<very high<low<medium. The findings showed that plants uptook P efficiently under unsubmerged conditions. N uptake was consistent after a fertilizer dose of 100 kg ha−1. From the quantitative measurements of nutrient uptake and Cobb-Douglas model analysis validated farmer information on fertilizer and crop yield. Results also revealed that averaging across all the villages an amount of 71 kg ha−1 is needed for P replenishment to maintain the yield along with water for increased soil moisture in lateritic soil. Finally, it is concluded that involving farmers will prevent soil deterioration in rainfed rice areas and a policy shift to develop optimal N and P management strategies for sustainable agriculture under unsubmerged soil conditions.

Deploying photovoltaic arrays in degraded grasslands is a promising win-win strategy for promoting grassland restoration and resolving land use conflicts

Photovoltaic (PV) facility installation occupying large land areas gradually expands into vast grasslands. The construction of PV arrays should be synchronized with the establishment of fences to prevent grazing and human disturbance. However, it is still being determined whether deploying PV arrays in degraded grasslands has better restoration effects than common grassland fencing, achieving a win-win for grassland restoration and resolving land use conflicts. Here, we investigated soil and vegetation characteristics to assess the different impacts of PV arrays, fencing, and free-grazing on restoration in the degraded grassland in the Songnen Plain, Northeast China. The results showed that the PV arrays and fencing significantly improved soil and vegetation parameters, with the PV arrays dramatically increasing carbon and nitrogen storage in plants (including aboveground, underground, and litter) and soil. The mixed linear model analysis showed that the experimental zones had a significant influence on the carbon and nitrogen pools in plants and soil. Compared to single grassland fencing, the PV arrays significantly improved the carbon storage of plants and soil, with increases of 30.19% and 17.93%, respectively. Furthermore, there was an observed increase of 9.44% and 0.75% in the nitrogen storage. Soil pH and bulk density were the main factors influencing soil carbon and nitrogen storage in the fenced zones. Increasing soil moisture in the PV array zones resulted in higher soil carbon and nitrogen storage than in the fenced zones. The PV arrays showed a 78.61% increase in annual mean soil carbon sequestration rates compared to the grassland restoration measures reported in previous studies. Overall, the PV array zone superimposed the dual effects of PV panels and their fences, with the ecological indicators showing a greater positive influence than common grassland fencing. Our results suggested that deploying PV arrays was a win-win strategy for promoting grassland restoration and resolving land use conflicts in degraded grasslands.

Monitoring hydrological changes with satellite data: Spring thaw's effect on soil moisture and groundwater in seasonal Freezing-Thawing zones

Due to the dense vegetation coverage in mountainous areas and difficulties in field monitoring in mid-high-latitude freezing-thawing zones, satellite and remote sensing technologies can be used to monitor long-term global hydrological changes. This study uses multiple satellite data of snow water equivalent (SWE), soil moisture (SM), and groundwater storage anomaly (GWSA) to analyse their spatial–temporal changes in the seasonal freezing-thawing Tumen River Basin. Water transformation during the thawing period is determined through groundwater level fluctuations and correlation analysis methods; thus, the recharge effects of snowmelt and seasonally frozen soil thawing on soil moisture and groundwater are identified. The snow begins to melt in February, and snow water equivalent decreases gradually from upstream to downstream after reaching the peak. Furthermore, seasonally frozen soil melts gradually from March. Soil moisture downstream is higher than that in the upper and middle reaches. Additionally, the GWSA increases gradually in the thawing period, which is high in mountainous areas and low in plains. The Spearman correlation coefficient among ΔSWE, ΔSM, and ΔGWSA is more significant than 0.5 and dependent on altitude. With snow and frozen soil melting, vertical infiltration and meltwater percolation increase soil moisture and GWSA. This phenomenon is predominant at low altitudes (<600 m) and pore phreatic groundwater in the middle and lower reaches. However, snowmelt is the dominant factor in groundwater recharge at high-altitude upper reaches. For seasonal freezing-thawing zones, a close water transformation was observed between snow melting, soil water thawing, and groundwater in spring. Thus, the environmental and ecological impact of spring snowmelt and floods in freezing-thawing zones can be monitored using multi-source data.

Ecovoltaics: Maintaining Native Plants and Wash Connectivity inside a Mojave Desert Solar Facility Leads to Favorable Growing Conditions

The installation of solar facilities is increasing rapidly in the Mojave Desert USA, with the largest facility in North America (3227 ha) currently being built 30 km north of Las Vegas, NV. At the state level, Nevada (USA) has developed an energy plan to diversify its energy portfolio by 2030 with green energy representing 50% of the energy produced. Although solar is considered a clean energy, it does require significant amounts of land and as such may have negative consequences at the habitat and ecosystem levels. A multi-year study was conducted to assess the impact a photovoltaic facility in the Mojave Desert had on the growth and physiological response of two native shrubs (Ambrosia dumosa and Larrea tridentata) growing inside and outside the facility. These species were selected because they were the dominant species at the site and are representative of desert scrub communities throughout the Mojave Desert. At the time of construction, native plants and washes were left intact inside the solar facility. The solar panel arrays were separated at either 8 m or 10 m. Plants were selected for monitoring on the basis of location: at the panel drip line, below the panels, or midway between panel rows. Abiotic factors, including PAR, reference evapotranspiration, precipitation, soil water in storage, and infiltration, were monitored bi-monthly. The growth and physiological status of the plants were assessed by monitoring leaf water potential, chlorophyll index, canopy temperatures, non-structural carbohydrates in the roots and stems, leaf tissue ion concentrations, stem elongation, and seed production. Plants at the bottom edges of the panels received more precipitation due to runoff from the panels, which led to increased soil moisture in the long spacing but not the short spacing. The lower soil water in storage in the short spacing was related to greater growth and higher soil water extraction. Although the area under the panels provided shade in the summer and warmer temperatures in the winter, the incoming PAR was reduced by as much as 85%, causing plants growing under the panels to be spindly with lower canopy volume (L. tridentata, p = 0.03) and seed yield (A. dumosa, p = 0.05). Ambrosia plants remained green in color year-round (not going into winter dormancy) inside the facility and had elevated levels of starch in their roots and stems compared with plants growing at the outside control sites (p &lt; 0.001). Larrea growing outside the facility had lower xylem water potentials compared with those inside the facility (p &lt; 0.001), lower chlorophyll index (p &lt; 0.001, Ambrosia as well), and lower stem elongation (p &lt; 0.001), supporting the conclusion that both Larrea and Ambrosia performed better inside the facility. Shifts in δ13 C suggested greater water-use efficiency at the locations with the least amount of soil water in storage. Our results support the installation of solar facilities that minimize the impact on native plants and wash connectivity (ecovoltaics), which should translate into a reduced negative impact at the habitat and ecosystem levels. Basedon our results, energy companies that embrace ecovoltaic systems that take an engineering and biological approach should provide acceptable environments for desert fauna. However, corridors (buffers) will need to be maintained between solar facilities, and fences will need to have openings that allow for the continuous flow of animals and resources.

Influence of Rate Effects, Temperature, and Moisture Content on the Geomechanical Behavior of Marine Clays

Abstract The study of the geomechanical behavior of marine clays is a basic requirement for project optimization of the oil and natural gas industry. As part of a large-scale project, this study explored the effects of moisture content, temperature, and rate effects using laboratory vane shear tests. A series of results has helped in the identification of the effects of ground freezing on the undrained shear strength. For temperatures below freezing (−2.0 °C) the undrained shear strength increases with increasing water content and decreases with increasing shear rates for applied angular velocities in the range of 0.0025– 0.015 rpm. Apparently, with the freezing of pore fluids, the shear strength is partially governed by the strength of the ice-soil particle bonds. The increase in shear rate appears to facilitate the breakage of the ice bonds and afterwards the ice crystals reducing the viscous effects on the mobilized shear strength. Conversely, samples tested at temperatures above freezing show an increase in undrained shear strength with the increase in the imposed angular velocity and decreases with increasing soil moisture. Based on these studies, it is concluded that rate effects should be coupled to the influence of temperature and moisture content in the design of offshore structures.