Increasing Soil Moisture Content Research Articles

EFFECTS OF RAINWATER HARVESTING PRACTICES ON BIOMASS YIELD AND MORPHOMETRIC TRAITS OF SORGHUM (Sorghum bicolor L. Moench) IN SEMI-ARID KITUI COUNTY, KENYA

<p><strong>Background</strong>: Sorghum is an important source of fodder in the semi-arid areas of Kenya. However, its biomass yield has remained low due to the low soil moisture content which is associated with low rainfall. <strong> Objective:</strong> To evaluate the synergistic effects of combining rainwater harvesting practices on biomass yield and the morphometric traits of sorghum in semi-arid Kitui County. <strong>Methodology</strong>: The study was conducted in a randomized complete block design under rainfed conditions between March and August 2021 at the Research Farm of South Eastern Kenya University. It had twelve treatments, including three farming systems (conventional flat planting, ridge and furrow, and zai pits) with three soil mulching types (transparent plastic film mulch, black plastic film mulch, and grass mulch). The farming systems without mulching were used as control treatments. Data were subjected to analysis of variance and means were separated using Fisher’s protected Least Significant Difference test at 0.05 %. <strong>Results:</strong> The zai pits with black plastic film mulch and flat planting with grass mulch had the highest and lowest moisture content of 68.65% and 52.5% respectively compared to flat planting. The highest biomass yield was observed in ridge-furrow with black plastic film mulch (3283.33kg ha-<sup>1</sup>) and ridge–furrow with transparent plastic film mulch (3266.03) and was not significantly different. The lowest biomass yield was recorded in conventional flat planting and zai pits and was not significantly different. In all treatments, there was a significant increase (p ≤ 0.05) in morphometric traits. <strong>Implications: </strong>The farming system and the type of soil mulching determined the increase of soil moisture content, biomass yield, and morphometric traits. <strong>Conclusion</strong>: Combining ridge-furrow and black plastic mulch is recommended to improve the biomass yield of sorghum in semi-arid Kitui County, and other areas with similar agroecological conditions.</p>

Microscopic deformation and fragmentation energy consumption characteristics of soils with various moisture contents using discrete element method

Increased soil moisture content commonly leads to higher resistance and energy consumption during agricultural operations. However, the impact of moisture content on soil microscopic deformation and fragmentation energy consumption characteristics remains unclear. In this study, discrete element models of sandy clay loam with different gravimetric water contents (15.0%, 18.8%, 21.6%, 24.1%, and 27.3%) were constructed for simulation experiments using coupled contact method (Hertz-Mindlin with bonding and Hertz-Mindlin with JKR). The degree of soil fragmentation and the rate of crack propagation were investigated. The results indicated that at fixed gravimetric water content, fissure rate exhibited a pattern of slow increase, rapid increase, and eventual stabilization with increasing compression displacement, while the fissure transfer coefficient showed a pattern of first increase and then decrease. At a fixed compression displacement, the increase in moisture content led to a decrease in both fissure rate and fissure transfer coefficient. The analysis of soil stress-strain characteristics and energy dissipation patterns found that soil with a gravimetric water content of 27.3% (close to soil liquid limit) exhibited no compression yield point; at a soil gravimetric water content of 15.0%, the minimum crushing energy (Udmin) was achieved (1.32 J), with a maximum elastic strain energy (Uemax) of 1.83 J. Similarly, at a soil gravimetric water content of 24.1%, the minimum crushing energy (Udmin) was reached (2.17 J), with a maximum elastic strain energy (Uemax) of 2.25 J. The comparison between actual and simulated results revealed low relative errors (<6%) in Udmin for all the above soil gravimetric water contents, suggesting the feasibility of our coupled discrete element model for assessing soil crushing energy consumption. This study revealed microscopic deformation and instability fragmentation mechanisms of soils with various moisture contents under vertical axial loads. Our findings provide novel method and strategy for developing the high-efficiency low-consumption soil fragmentation model.

Intensive ammonium fertilizer addition activates iron and carbon conversion coupled cadmium redistribution in a paddy soil under gradient redox conditions

While over-fertilization and nitrogen deposition can lead to the enrichment of nitrogen in soil, its effects on heavy metal fractions under gradient moisture conditions remains unclear. Here, the effect of intensive ammonium (NH4+) addition on the conversion and interaction of cadmium (Cd), iron (Fe) and carbon (C) was studied. At relatively low (30–80 %) water hold capacity (WHC) NH4+ application increased the carbonate bound Cd fraction (F2Cd), while at relatively high (80–100 %) WHC NH4+ application increased the organic matter bound Cd fraction (F4Cd). Iron‑manganese oxide bound Cd fractions (F3Cd) and oxalate-Fe decreased, but DCB-Fe increased in NH4+ treatments, indicating that amorphous Fe was the main carrier of F3Cd. The variations in F1Cd and F4Cd observed under the 100–30-100 % WHC treatment were similar to those observed under low moisture conditions (30–60 % WHC). The C=O/C-H ratio of organic matter in soil decreased under the 30–60 % WHC treatment, but increased under the 80–100 % WHC treatment, which was the dominant factor influencing F4Cd changes. The conversion of NH4+ declined with increasing soil moisture content, and the impact on oxalate-Fe was greater at 30–60 % WHC than at 80–100 % WHC. Correspondingly, genetic analysis showed the effect of NH4+ on Fe and C metabolism at 30–60 % WHC was greater than at 80–100 % WHC. Specifically, NH4+ treatment enhanced the expression of genes encoding extracellular Fe complexation (siderophore) at 30–80 % WHC, while inhibiting genes encoding Fe transmembrane transport at 30–60 % WHC, indicating that siderophores simultaneously facilitated Cd detoxification and Fe complexation. Furthermore, biosynthesis of sesquiterpenoid, steroid, butirosin and neomycin was significantly correlated with F4Cd, while glycosaminoglycan degradation metabolism and assimilatory nitrate reduction was significantly correlated with F2Cd. Overall, this study gives a more comprehensive insight into the effect of NH4+ on activated Fe and C conversion on soil Cd redistribution under gradient moisture conditions.

Organization of forest geosystems in the Lower Amur region by a case study of the Komsomol’sky Nature Reserve

This article is devoted to the structural-functional organization of the forest geosystems of Komsomol’sky Nature Reserve located in the south of the Lower Amur Region. It considers a landscape organization model built using the information theory methods. The model is represented as a block diagram consisting of digraphs, in whose center there are landscape features. This model is a modified version of the previously published one for the studied territory. It is built on the basis of richer field data and with the addition of previously unused landscape features. Weak links of medium density predominate in the model, which may indicate the stability of the forest geosystems formed there. Our analysis shows that the main factors determining the structure of Komsomol’sky Nature Reserve’s forest geosystems are altitudinal-exposure zonality, altitude, lithology of parent rocks, and soil hydrothermal conditions. It is established that the stand of timber is directly related to the humus soil horizon lithomass: it decreases with an increase in lithomass. Plants biomass is highly dependent on the steepness of slopes: it decreases with its increase. Separate relationships have been revealed for plant layers. The herbaceous layer height decreases with an increase in the altitude and lithom ass in the soil. The herbage floristic diversity differs greatly in land facie groups and has a maximum in the ridge-top areas of the slopes and at the foot hill. The shrub layer height depends on soil moisture content, lithology of parent rocks and lithomass: it de-creases with increasing soil moisture content most of all and increases with increasing lithomass in the soil. A relationship has been found only with the lithomass in the soil for all tree layer features. A lithomass increase has a depressing effect on trees.

Effects of Different Modifiers on Aggregates and Organic Carbon in Acidic Purple Soil

The aim of this study was to examine the effects of different modifiers on the changes in aggregates and organic carbon in acidic purple soil， providing a scientific basis for the remediation of acidic purple soil. Using purple soil as the research object， a total of six treatments were set up， including no fertilization （CK）， single fertilization （F）， fertilization with lime （SF）， fertilization with organic fertilizer （OM）， fertilization with biochar （BF）， and fertilization with distiller's grains ash （JZ）. We compared the composition of aggregates in acidic purple soil under the application of different modifiers， as well as the distribution pattern of organic carbon in aggregates of different particle sizes. Combined with the stability indicators of aggregates， we sought to clarify the impact of different modifiers on the structure of aggregates in acidic purple soil. The results showed that fertilization significantly increased the soil pH， with the JZ treatment being the most effective. Fertilization significantly increased soil organic matter content， with the OM treatment showing the largest increase. The BF and OM treatments significantly reduced soil bulk density， whereas the SF and BF treatments significantly increased soil moisture content （P &lt; 0.05）. All treatments used &lt; 0.25 mm aggregates as the dominant particle size. Fertilization could significantly increase the content of large aggregates （aggregate structure units with diameter &gt; 0.25 mm）. At the same time， fertilization treatments significantly increased the soil geometric mean diameter （GMD）， average weight diameter （MWD）， and R0.25 value （ &gt; 0.25 mm aggregate content） and reduced the fractal cone number （D） and aggregate destruction rate （PAD） values （P &lt; 0.05）. Fertilization also promoted the aggregation and stability of soil aggregates， with the OM treatment having the greatest effect. Compared with that in the CK treatment， fertilization could significantly increase soil organic carbon content by 31.71%-209.67%， with the OM treatment showing the most significant change. Different treatments of soil organic carbon were mainly distributed in large aggregates. Compared with that in the CK treatment， each treatment significantly increased the contribution rate of organic carbon in large aggregates by 19.34%-47.76%， with the OM treatment having the most significant effect （P &lt; 0.05）. In general， chemical fertilizer combined with organic fertilizer could promote the formation of large aggregates in acidic purple soil， improve the stability of soil aggregates， and increase the content of soil organic carbon， which is an effective measure to improve the soil structure and improve the quality of acidic purple soil.

Hedgerow Olive Orchards versus Traditional Olive Orchards: Impact on Selected Soil Chemical Properties

Olive orchards cover over 10 million hectares worldwide, with production techniques undergoing significant changes in the past three decades. The traditional rainfed approach, involving minimal inputs, has given way to irrigated super-intensive systems with higher planting density, increased productivity, a greater use of fertilizers and phytopharmaceuticals, and total mechanization. Its impact on soil chemical properties remains a topic of great debate, and no definitive consensus has been reached. Our main objective was to examine the different effects of traditional olive orchards and super-intensive orchards on soil chemistry over a decade. We collected and analyzed 1500 soil samples from an irrigation perimeter in southern Portugal in 2003 and 2013. Our findings indicate that, compared to traditional olive orchards, super-intensive ones show, in a decade, a significant decrease in soil organic matter (less 22.8%—p &lt; 0.001), namely due to the increase in mineralization caused by an increase in soil moisture content as a result of irrigation practice, and an increase in sodization (more 33.8% of Ext Na—p &lt; 0.001) highlighting the importance of monitoring this factor for soil fertility. In comparison to other irrigated crops in the region, super-intensive olive orchards promote a significant soil acidification (from 7.12 to 6.58), whereas the pH values of the other crops increase significantly (3.3%, 13.5%, and 3.0% more in corn, tomato, and cereals, respectively). Mainly because of the decrease in organic matter levels with soil acidification and soil sodization, we can underline that hedgerow olive orchards can affect soil characteristics negatively when compared with traditional ones, and it is necessary to adopt urgent measures to counter this fact, namely sustainable agriculture practices.

A regime shift between soil moisture and temperature in the 1950s over the permafrost region of Northeast China

AbstractPermafrost is one of the essential carbon pools in the world. Due to limited studies on historical soil moisture changes and the coupling relationship between soil moisture and temperature in permafrost regions, significant uncertainty exists in the carbon loss in permafrost predicted by different models under global warming scenarios. Based on the tree‐ring width chronology of Pinus sylvestris var. mongholica Litv. growing in the southern edge of the Eurasian continuous permafrost zone, we reconstructed the summer (June–September) 0–1 m soil moisture variations from 1705 to 2009, which could explain 45.6% of the variance in the observed soil moisture. Overall, local precipitation and temperature exhibited statistically significant positive feedback (p &lt; 0.001) to soil moisture before the 1950s, indicating that the warm/humid climate pattern was conducive to soil moisture conservation before the Anthropocene Epoch. However, the effect of temperature on soil moisture has shifted suddenly to negative since the 1950s, implying that the positive soil moisture‐temperature relationship during the past three centuries has been disrupted by the unprecedented warming in the Modern Warm Period. Furthermore, we found that the temporal relationship of the soil moisture‐temperature (15‐year sliding correlation) in the study area is negatively regulated by the global mean temperature variations (p &lt; 0.01). The regime shift between soil moisture and temperature might be attributed to the superimposed influence of natural and anthropogenic factors since the 1950s. Although the warming leads to the melting of the permafrost layer, and thus the increase in soil moisture content, the enhanced evapotranspiration caused by warming up results in more water loss and drier soil. This study provides historical evidence of shifted soil moisture‐temperature coupling in the permafrost zone, warning that soil moisture in the permafrost region may further decline under global warming scenarios, thereby affecting vegetation growth and forest carbon sequestration potential.

Relationships between Soil Moisture and Visible–NIR Soil Reflectance: A Review Presenting New Analyses and Data to Fill the Gaps

The ability to precisely monitor soil moisture is highly valuable in industries including agriculture and civil engineering. As soil moisture is a spatially erratic and temporally dynamic variable, rapid, cost-effective, widely applicable, and practical techniques are required for monitoring soil moisture at all scales. If a consistent numerical relationship between soil moisture content and soil reflectance can be identified, then soil spectroscopic models may be used to efficiently predict soil moisture content from proximal soil reflectance and/or remotely sensed data. Previous studies have identified a general decrease in visible–NIR soil reflectance as soil moisture content increases, however, the strength, best wavelengths for modelling, and domain of the relationship remain unclear from the current literature. After reviewing the relevant literature and the molecular interactions between water and light in the visible–NIR (400–2500 nm) range, this review presents new analyses and interprets new 1 nm resolution soil reflectance data, collected at &gt;20 moisture levels for ten soil samples. These data are compared to the results of other published studies, extending these as required for further interpretation. Analyses of this new high-resolution dataset demonstrate that linear models are sufficient to characterise the relationship between soil moisture and reflectance in many cases, but relationships are typically exponential. Equations generalising the relationship between soil MC and reflectance are presented for a number of wavelength ranges and combinations. Guidance for the adjustment of these equations to suit other soil types is also provided, to allow others to apply the solutions presented here and to predict soil moisture content in a much wider range of soils.

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.

The Effect of Tillage Depth on some Machinery Unit Performance Indicators, Soil Physical Properties and Germination Percentage using Combine Equipment

A field experiment was conducted to determine the effect of the locally manufactured agricultural machine on some performance indicators of the mechanical unit and some physical soil properties in a silty clay loamy soil texture in one of the fields of the College of Agricultural Engineering Sciences / University of Baghdad/Al-Jadriya for the spring season of 2023. The experiment used a tractor type (MF-650), and the study included one factor, the plowing depths, with three levels: 15, 20, and 25 cm. The study examined some performance indicators of the mechanical unit, including: pulling force, fuel consumption, slippage percentage, soil bulk density, soil moisture content, total soil porosity, germination percentage, number of dropped seeds, and the percentage of broken or damaged dropped seeds. The experimental design used was a randomized complete block design (RCBD) with three replications, and the least significant difference (LSD) test was used at a significance level of 0.05 to compare the means of the variables. The results indicated that increasing the plowing depth from 15 to 20 and then to 25 cm led to a significant increase in the percentage of slippage, which increased from 4.37% to 7.37% and then to 14.33%, respectively. The pulling force also increased from 5.33 to 9.67 and then to 14.44 kilonewtons, respectively. The fuel consumption increased from 43.32 to 56.84 and then to 66.67 liters per hectare, respectively. The bulk density of the soil increased from 1.06 to 1.08 and then to 1.15 micrograms per cubic meter, respectively. There was an increase in soil moisture content from 14.11 to 15.19 and then to 16.63%, respectively. There was no significant effect of plowing depth on the percentage of germination, the number of dropped seeds, and the percentage of broken seeds.

Response of NPK Fertilization and Irrigation in Nutrient and Soil Moisture Distribution Under High-Density Apple Plantation in the NW Himalayan Region

ABSTRACT Drip fertigation provides enormous opportunities for the effective utilization and distribution of water and nutrients in sustainable management of orchard. Under various drip irrigation and fertigation schedules, the analysis of NO3 −-N and NH4 +-N distribution within the soil has been found to be efficacious to enhance the crop growth. Over the 2-year period of study (2019 and 2020), the response of NPK fertilization and irrigation in nutrient and soil moisture distribution under high-density apple plantation in the NW Himalayan region was investigated. In the present study, under drip irrigation, the wetting front extended up to 45 cm horizontally from the emitter; however, the maximum increase in soil moisture content remained confined near the emitting point. The soil moisture content decreased consistently with the increasing horizontal distance from the emitter. Drip irrigation recorded a higher soil moisture content at the surface soil depth of 0–15 cm compared to conventional surface irrigation, where the sub-surface soil depths of 15–30 cm registered a higher moisture content. The distribution of NO3 −-N and NH4 +-N content under drip fertigation nearly followed the soil moisture distribution pattern. The NO3 −-N and NH4 +-N content was maximum below the emitter and decreased thereafter with the increasing lateral distance from the emitter as nutrient mobility in soil is primarily governed by water movement. The decreasing trend of NO3 −-N and NH4 +-N with the increasing lateral distances is in accordance with the water distribution pattern under drip irrigation. The nutrient mobility is proved to be well pronounced under the drip fertigation system, and nutrients carried along with the water movement get concentrated near the outer periphery of the wetting zone.

Effect of Terracing on Soil Moisture of Slope Farmland in Northeast China’s Black Soil Region

The impact of terracing construction on the soil moisture content of slope farmland was analyzed at three sites in northeast China’s black soil region, across a range of latitudes and hydrological, temperature and soil quality conditions. At each research site, slope farmland with terracing was compared to unterraced slope farmland with a similar shape and gradient. During the wet crop growth period (July) and dry postharvest period (October) of 2022, the TRIME-PICO64TDR soil moisture measuring instrument was used to measure the soil moisture content at depths of 0–60 cm. Terracing increased soil moisture content by up to 2.83 percentage points during the crop growth period and by up to 1.69 percentage points during the postharvest period. Terracing had a significant impact on the volumetric soil moisture content of the shallower soil layer (0–30 cm) during the growing period, and on the volumetric soil moisture content of the deeper soil layer (30–60 cm) during the postharvest period. Terracing weakens the effect of slope position on volumetric soil moisture, reducing differences in volumetric soil moisture content among different slope positions. The difference in the water conservation benefit of terracing among the sites is mainly related to soil quality: the lower the soil bulk density and the higher the silt clay content is, the greater the benefit of terracing for retaining moisture. The findings of this study can be beneficial for guiding management measures for slope arable soil in black soil regions around the world.

Response of the Anchoring Performance at Betula platyphylla’s Root–Soil Interface to Cyclic Loading

In dealing with issues such as soil erosion and slope instability, plant roots enhance the shear strength of the soil mass through their anchoring effect. However, in nature, cyclic loads such as flash floods and blizzards indirectly impose fatigue effects on plant root systems. To explore the impact of cyclic loads on the anchoring capacity of plant roots, this paper selects the roots of Betula platyphylla as the research object and uses a monotonic load and cyclic load as two loading modes. Under different loading amplitudes (25%, 50%, and 75%), root diameters and burial depths (50 mm, 100 mm, and 150 mm), and soil moisture contents (11.85%, 13.85%, and 15.85%), the effects of each factor on the anchoring capacity of the roots under cyclic loading are analyzed. The results showed that the root–soil interface exhibited two failure modes under different cyclic load amplitudes, and the cyclic load significantly reduced the maximum friction of the root–soil interface. As the cyclic load amplitude increased (from 25% to 75%), the hysteretic curve envelope area increased, and the growth rate of cumulative residual slip changed from decreasing to decreasing and then increasing. A good correlation was found between cumulative residual slip and the number of loading cycles, and the three characteristic slips were correlated with loading amplitude but not significantly with diameter. The increase in soil moisture content, root embedment depth, and diameter led to an increase in the ratio of the two maximum friction forces. It was shown that a certain degree of plasticity exists at the root–soil interface to resist environmental stresses in nature. At high fatigue stress levels, the root–soil interface is more nonlinear, and as the load amplitude increases, more energy is dissipated, and bond damage between the root–soil interface becomes more pronounced. The root–soil interface gradually degraded under long-term cyclic loading, whereas the increase in root depth and soil water content could resist the negative effect of cyclic loading on anchorage capacity, and the resistance effect became more and more obvious with the increase in diameter.

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.

Effects of Microbial Fertilizer on Physicochemical Properties and Bacterial Communities of Saline Soil Under Brackish Water Irrigation

The improvement of saline soil with microbial fertilizer has numerous advantages including high efficiency, green environmental protection, etc. At the same time, applying microbial fertilizer is an effective way to safely use brackish water. Based on the moderately saline soil in the Hetao irrigation area, four treatments of F1 (4500 kg·km-2), F2 (7500 kg·km-2), F3 (10500 kg·km-2), and CK without microbial fertilizer were applied under brackish water irrigation using Lycium barbarum as the indicator plants. The aim was to study the effects of different microbial fertilizer application rates on soil ions, soil moisture content, pH value, nutrients, and bacterial community in four key growth stages of L. barbarum (flowering stage, fruit expansion stage, full fruit stage, and deciduous stage). The results showed that, compared with that in CK, F1 only significantly decreased Na+ content in the first two growth stages (P<0.05), whereas F2 and F3 significantly decreased Na+ content in the whole growth period (P<0.05), with an average reduction of 33.66% and 57.98%, respectively, and F3 significantly increased soil moisture content (MC), organic matter (OM), alkaline hydrolysis nitrogen (AN), and available phosphorus (AP) contents (P<0.05) during the whole growth period. In the flourishing period of L. barbarum, the Shannon index of F3 increased by 4.41% compared with that of CK. The dominant bacterial phyla in the soil were Proteobacteria, Bacteroidetes, and Actinobacteria, and the dominant bacterial genera were Sphingomonas and Pseudomonas. The most abundant functions of bacterial communities in the study area were chemoheterotrophy and aerobic chemoheterotrophy, with an average relative abundance of 15.07% and 13.16%, respectively. The application of microbial fertilizer increased the chitinolysis function and chloroplast functions of soil bacteria, which F2 increased to the highest degree. Canonical correlation analysis (CCA) showed that MC, Na+, and OM were important factors affecting the composition of the bacterial community. The correlation heat map showed that MC was positively correlated with Planctomycetes (P<0.01), and Gp6 was positively correlated with AN (P<0.01). Compared with that in CK, the F3 treatment increased the relative abundance of Gp6 and optimized the community structure during the growth period. In conclusion, the application of 10500 kg·km-2 microbial fertilizer (F3 treatment) under brackish water irrigation could significantly reduce soil salinity, increase nutrients, and improve the diversity of the soil bacterial community structure, which is conducive to the safe utilization of brackish water and the maintenance of soil ecological health.

Straw Returning Measures Enhance Soil Moisture and Nutrients and Promote Cotton Growth

In order to investigate the comprehensive effects of straw returning on soil physical and chemical properties, as well as cotton growth in Jiangsu, China, and to determine suitable high-yield and efficient straw returning measures, this study implemented three different straw returning methods: straw mulching (SM), straw incorporation (SI), and straw biochar (BC), with no straw returning served as a control (CT). The study aimed to assess the impact of these straw-returning measures on soil nutrients, soil moisture content, soil water storage, and deficit status, as well as primary indicators of cotton growth. The findings revealed that the total available nutrient storage under SM, SI, and BC showed an increase of 11.93%, 11.15%, and 32.39%, respectively, compared to CT. Among these methods, BC demonstrated a significant enhancement in soil organic carbon content, available phosphorus, and available potassium. Furthermore, SM exhibited a considerable increase in soil moisture content across all layers (0–40 cm), resulting in an average water storage increase of 7.42 mm compared to CT. Consequently, this effectively reduced the soil water deficit during the cotton development period. Moreover, the height of cotton plants was increased by SM, SI, and BC, with SM promoting the greatest growth rate of up to 66.87%. SM resulted in an 11.17 cm increase in cotton plant height compared to CT. Additionally, SM contributed to higher chlorophyll content in leaves at the end of the growth period. Overall, the indicators suggest that straw mulching is particularly effective in enhancing soil moisture and nutrient distribution, especially during dry years, and has a positive impact on promoting cotton development. Based on the results, straw mulching emerges as a recommended straw-returning measure for improving soil quality and maximizing cotton production in the study area.

Changes in air dose rates due to soil moisture content in the Fukushima prefecture forests

Radionuclides released and deposited because of the 2011 Fukushima Dai-ichi Nuclear Power Plant accident caused an increase in air dose rates in Fukushima Prefecture forests. Although an increase in air dose rates during rainfall was previously reported, the air dose rates in the Fukushima forests decreased during rainfall. This study aimed to develop a method to estimate rainfall-related changes in air dose rates, even in the absence of soil moisture data, in Namie-Town and Kawauchi-Village, Futaba-gun, Fukushima Prefecture. Moreover, we examined the relationship between preceding rainfall (Rw) and soil moisture content. The air dose rate was estimated by calculating the Rw in Namie-Town from May to July 2020. We found that the air dose rates decreased with increasing soil moisture content. The soil moisture content was estimated from Rw by combining short-term and long-term effective rainfall using half-live values of 2 h and 7 d and considering the hysteresis of water absorption and drainage processes. Furthermore, the soil moisture content and air dose rate estimations showed a good agreement with coefficient of determination (R2) scores >0.70 and >0.65, respectively. The same method was tested to estimate the air dose rates in Kawauchi-Village from May to July 2019. At the Kawauchi site, variation in estimated value is relatively large due to the presence of water repellency in dry conditions, and the amount of 137Cs inventory was low, so estimating air dose from rainfall remained a challenge. In conclusion, rainfall data were successfully used to estimate soil moisture and air dose rates in areas with high 137Cs inventories. This leads to the possibility of removing the influence of rainfall on measured air dose rate data and could contribute to the improvement of methods currently used to estimate the external air dose rates for humans, animals, and terrestrial forest plants.

Effects of biostimulant application on soil biological and physicochemical properties: A field study

AbstractIntroductionDespite their potential benefits, it is not well understood how the application of biostimulants influences soil biological properties and their microbial communities in field conditions. In this study, we aimed to evaluate the impacts of biostimulants on soil biological and physicochemical properties relevant to soil health.Materials and MethodsTo achieve this, we conducted a field study to investigate the effects of two types of commercially available biostimulants, Universal Natural Plant food (UNP) and Converte Seed Primer (CSP), on microbial activity, bacterial and fungal abundance, community structure and diversity, and soil chemical and physical properties across two depths (0–10 and 10–20 cm) from five sites under either wheat or pasture cultivation.ResultsOur findings suggest that application of UNP stimulated microbial activity by 40.1% in surface (0–10 cm) and 36.4% in deeper (10–20 cm) soil, but was dependant on site. Effects were generally greater in grasslands compared with arable soils. At sites where UNP stimulated microbial respiration, substrate‐induced respiration was also stimulated in surface soils and was associated with increased soil moisture content and higher total carbon and nitrogen. At the one site where UNP was combined with CSP, soil enzymes associated with carbon and nitrogen cycling were stimulated in UNP and UNP + CSP treatments. Total bacterial and fungal abundance and their alpha diversity did not respond to biostimulant treatment. However, microbial indicator communities were identified that responded positively to UNP and CSP addition across the two depths. Bacterial indicator species included Elsterales, Propionibacteriales, Solibacterales, Candatus, Reyranellales and Sphingomonadales, but differed between depths. For the fungal indicator species Filobasidiales (Basidiomycota) and Pleosporales (Ascomycota) were strong responders and common across both depths.ConclusionOverall, our results suggest some positive effects of biostimulants on soil biological and physicochemical properties. Further long‐term studies should be conducted to evaluate the effects of biostimulants on crop yield and farm resilience.

Interactive effects of soil moisture, nitrogen fertilizer, and temperature on the kinetic and thermodynamic properties of ammonia emissions from alkaline soil

Soil moisture and nitrogen fertilizer application rates are among the key factors affecting ammonia (NH3) emission, particularly in alkaline soil. However, the dynamic and thermodynamic properties of NH3 emissions from alkaline soils have not been extensively studied. In this study, we conducted an incubation experiment and theoretical analysis to investigate NH3 emission dynamics and thermodynamic properties under treatments involving different moisture levels (5%, 15%, 25%, and 35%), nitrogen fertilizer application rates (0, 172.4, and 344.8 mg kg−1), and temperatures (10, 20, 30, and 40 °C). The accumulative NH3 emissions varied significantly among the different moisture, temperature, and nitrogen treatment conditions and exhibited a logarithmic growth trend over time. The highest accumulative NH3 emissions occurred under the following conditions: 344.8 mg kg−1 nitrogen fertilizer, 5% moisture, and 40 °C temperature. The highest average emission rate constant (KN) throughout the entire incubation period was obtained at 40 °C. The KN of NH3 emissions in the high-temperature region (30–40 °C) was more sensitive to temperature. With increasing soil moisture content, the activated free energy (ΔG) initially increased and then decreased. As the nitrogen fertilizer application rate increased, the ΔG decreased, thereby leading to higher NH3 emissions. Combining the kinetic and thermodynamic parameters revealed that temperature, soil moisture, and nitrogen fertilizer application rate were key factors influencing NH3 emissions in alkaline soil, with the nitrogen fertilizer application rate having a greater impact than that of temperature, soil moisture, and their coupling. These findings provide valuable insights into the thermodynamic and kinetic control mechanisms of NH3 emissions, which can be regulated by fertilization and irrigation methods that consider the nitrogen cycle in alkaline soils.