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The objective of this study is to enhance the capacity of struvite-phosphate forming reactor utilized in the production of phosphorus fertilizer from wastewater collected from mobile toilets, characterized by phosphorus (P) concentrations of 5.0 ± 1.1 g/l. The experimental procedure comprised three sequential phases: the first phase involved the precipitation of struvite-phosphate using the forming reactor; the second phase focused on pelletizing the P product with sugar milling wastes as filler; and the third phase involved assessing the bioavailability of P in agricultural soils. Experimental design entails batch experiments with the operational variables including the Mg:P molar ratio and pH. Results from nine experiments (3 × 3) indicate that (1) the percentage of phosphorus recovery ranged from 1.9 to 65.2, with a peak observed at high pH values, (2) optimal phosphorus recovery is attained at Mg:P ratio of 1.25 and pH of 9 during precipitation, and (3) the EDS analysis confirms the presence of major elements with phosphorus constituting the predominant component at 13.1%weight. Moreover, P leaching in soil predominantly occurred after the 7th day among the various soil types with the 90-days dissolution efficiency in soil of 97.7 ± 0.6, 86.9 ± 4.1, and 88.0 ± 3.0 for sandy loam, silt loam, and clay loam, respectively. These findings underscore the viability of achieving substantial phosphorus recovery through the utilization of a struvite-phosphate forming reactor via chemical precipitation, with additional evidence suggesting effective leaching of pellets in sandy loam soil, thereby highlighting its potential for widespread implementation in both phosphorus recovery and struvite fertilizer production on a large scale. [ABSTRACT FROM AUTHOR]

Introduction: Response to fertilization with biochar in contaminated soils for forage crops lacks comprehensive understanding. This study delves into the role of biochar in enhancing soil pH and phosphorus (P) and potassium (K) availability for ryegrass (Lolium perenne) in clay and silt loam metal-contaminated soils. Methods: Two pot experiments were conducted using switchgrass-derived biochar (SGB) and poultry litter-derived biochar (PLB) with varying biochar application rates: one without plants and the other with ryegrass. Results: Results demonstrated a significant rise in soil pH with increasing biochar rates, particularly notable for the PLB experiment with plants, attributed to PLB's superior buffer capacity. PLB significantly improved ryegrass productivity, evident in germination percentage, plant population, and biomass, especially at a 0.5-1% biochar application rate. However, excessive biochar application (2-4%) hindered plant growth. Discussion: PLB at 1% application sufficed to barely surpass critical P and K thresholds for optimal ryegrass production, whereas SGB fell short of meeting these thresholds, highlighting the importance of biochar feedstock selection. While biochar shows promise for metal remediation and nutrient enhancement, caution is advised against excessive application, considering potential nutrient contamination risks based on feedstock variations. [ABSTRACT FROM AUTHOR]

Silt loam soils in the mid-southern United States are prone to soil erosion, crusting, and general soil degradation. A field experiment was established at three field sites in northeast Arkansas to evaluate the effect of cover crop and tillage management on cash crop yield and the physical properties of soil health, specifically infiltration rate and aggregate stability. Cover crop management included cereal rye, wheat and crimson clover, and a winter fallow. Tillage management included tillage and no-tillage. During the two-year study, yield was not significantly influenced by different tillage treatments. The cover crop treatment had greater yield than the no-cover crop treatment (5091 vs. 4264 kg ha−1) at one site in one of the years. Water infiltration was significantly improved with cover crops compared to with no-cover crops, with a 52% and 64% increase at Walcott and Magnolia, respectively. Soil aggregate stability was significantly improved with no-tillage as compared with tillage in both years at Walcott, with a 16% and 58% increase in 2015 and 2016, respectively. Both cover crop and tillage management can have significant impacts on soil physical properties in a short period of time. [ABSTRACT FROM AUTHOR]

Direct seeded aerobic rice (DSR) is an emerging production system in Asia due to declining water availability and labor scarcity. Iron (Fe) deficiency is a severe problem in DSR as Fe2+ oxidized to Fe3+ and become unavailable to plants. Seed treatment is one of the emerging approaches to deal with Fe deficiency and content in rice crop to compensate this issue. Hence, pot experiment was planned in randomized block design to study the effect of Fe seed priming through different sources, i.e., iron sulfate (FeSO4.7H2O), Chelated iron (Fe-EDTA) and nano iron (FeONPs) and their levels on yield and Fe content in direct seeded aerobic rice (variety PR 126) under sandy loam and silt loam soils with three replications. On an average, seed priming with FeSO4.7H2O solution (1.0% Fe) showed the highest increase in grain yield (12.7%) over the control. On the other hand, increasing dose of Fe from 0.5 to 1.0% through Fe-EDTA showed adverse effects on rice yield due to higher residual effects. The plant height and chlorophyll content in rice plants varied from 26.1 to 42.2 cm and from 30.9 to 35.1 as SPAD value with maximum content in treatment having FeSO4.7H2O (0.5%Fe) in both the soils. The total and ferrous Fe content in rice plants ranged from 42.7 to 62.2 mg kg−1 and from 35.8 to 41.0 in harvested grains with the highest content in treatment having Fe-EDTA (0.5%Fe) followed by treatment FeSO4.7H2O (1.0%Fe) and treatment Fe-EDTA (0.25%Fe), respectively. Thus, seed priming of rice with 1.0%Fe solution using FeSO4.7H2O can be used for further studies to reduce Fe malnutrition in global population. [ABSTRACT FROM AUTHOR]

Potassium (K) nutrition and drought stress affect soybean (Glycine max (L.) Merr.) vigor and productivity through the combined impacts on water regulation. A study was conducted with soybean grown in 18.9‐L buckets under a rain out shelter to determine how the interaction between these crop stresses at various growth stages influences the crop leaf K concentration, biomass production, total K uptake (TKU), grain yield, and temperature of the uppermost fully expanded trifoliate. Treatments included soybean grown with and without preplant fertilizer K, soil moisture at 50% (drought) or 80% (well‐watered) field capacity, imposed drought during vegetative growth (V3–V7), flowering (R1–R3), pod development (R4–early R6), and seed development (R5–mid‐R6) on two different silt loam soils. Widespread K deficiencies were observed during the study across all treatments. Drought stress significantly (p < 0.05) reduced the TKU, aboveground biomass production, and grain yield. The crop growth stage when drought stress was imposed was a significant factor, with greater reductions in plant response parameters when stress was imposed during reproductive growth. Preplant fertilizer K increased trifoliolate K concentrations and TKU in drought conditions, but did not increase the grain yield of well‐watered soybean. Leaf temperature increased when under drought stress compared to well‐watered soybean (p < 0.0001) but the impact of crop K nutrition status on leaf temperature was inconclusive because of widespread K deficiencies. Results emphasize the complexity of the interactions between K nutrition and drought stress in soybean, as drought stress impeded K uptake, exacerbated K deficiencies, and limited yield. Core Ideas: Drought stress exacerbated the impacts of K deficiency in soybean.Leaf temperature increased when under drought stress across growth stages but was inconclusive when K deficient.Total K uptake and biomass production are affected by both K availability and drought stress across growth stages.Drought stress during reproductive stages reduces total K uptake, biomass, and grain yield to a greater degree. [ABSTRACT FROM AUTHOR]

The evaporation (EV) method is a widely used experimental approach to determine unsaturated hydraulic conductivity (UHC) and soil water retention (SWR) functions. However, the EV method has some limitations in evaluating accurate UHC values near the wet range. This restricts the working range of the models that utilize these UHC values for predicting soil water content and water fluxes for problems involving wet conditions (e.g., infiltration under ponding conditions). Our experimental study shows that when using the EV method, tensiometer offset errors as low as 1 cm can cause problems with wet-range measurements. Current methods to overcome these errors are expensive, inefficient, or cumbersome. In this study, we developed an improved EV method that utilizes a simple experimental protocol for standardizing the soil saturation procedure and a robust calibration method to quantify tensiometer offset errors. The proposed approach utilizes existing EV method hardware without requiring additional specialized instrumentation. Experiments performed using a silt loam soil sample show that our approach can extend the working range of the EV method to the wet range. Therefore, reliable estimates of the UHC and SWR functions can now be obtained over the entire range of soil suction heads. Our study also contributes to a better understanding of the EV method and uses this knowledge for collecting reliable and reproducible SWR and UHC data. The improved EV method is simple, effective, and cost-efficient. This method has the potential to greatly improve soil water content predictions, leading to better-informed decisions for groundwater resources management, sustainable agriculture, and environmental protection. [ABSTRACT FROM AUTHOR]

The creation of undesirable (soggy) sauerkraut resulted in the loss of $1,000,000 worth of organic sauerkraut in 2022, which prompted a multistep investigation of the cause and potential solution. The cause of this condition has been previously reported as unique fermentation conditions and the lack of key trace nutrients essential for cabbage (Brassica oleracea var. capitata) cell wall integrity. Because the condition was limited to organic sauerkraut in 2022, this investigation initially focused on differences in fermentation conditions between organic and conventional sauerkraut. No differences in fermentation conditions accounted for the condition; therefore, attention was focused on analyzing the mineral content of cabbage grown for sauerkraut production that pinpointed a deficiency in critical micronutrients such as iron, copper, manganese, boron, and zinc. This deficiency was traced to the use of poultry manure that was contaminated with glyphosate residue from conventionally fed turkeys and chickens that consumed genetically engineered (GE) feed and used as the fertilizer for organic cabbage production. The presence of glyphosate, a potent mineral chelator and antibiotic, was identified as a significant factor that impairs the absorption and physiological function of essential minerals in the shikimate metabolic pathway whereby cell walls and lignin are produced, thus compromising the structural quality of the sauerkraut. After this discovery, the study progressed to evaluate various remediation strategies aimed at eliminating glyphosate from the soil and restoring nutrient uptake. Corn grain and silage were selected as the test crops for this phase. Among the tested remediation solutions were raw sauerkraut juice containing Lactobacillus plantarum, which is reported to degrade glyphosate in the rumen of dairy cows and two patented proprietary microbial mixtures, PB027 and PB027SK, that degrade glyphosate by all three of the known metabolic pathways. These treatments were specifically formulated to degrade residual glyphosate in the soil. The results showed that these interventions could reduce soil glyphosate levels by 80% to 90% within 6 to 7 months to significantly enhance both the yield and quality of corn grain and silage. The increase in corn grain yield from glyphosate degradation on the Shiocton silt loam soil was 907.89 kg·ha-1 (13.5 bushels/acre). The increase in yield on the irrigated Kidder sandy loam soil was quantified at 726.31 kg·ha-1 (10.8 bushels/acre) for corn grain and 6.62 t·ha-1 (2.68 t/acre) for silage, with an additional improvement in silage feed quality beneficial for milk production. The findings underscore the importance of addressing both micronutrient sufficiency and glyphosate residue in soil to ensure the optimal growth of cabbage and the quality of sauerkraut produced. By successfully identifying manure as a subtle source of nutrient immobilization and implementing effective soil remediation techniques, this research highlights a clear path forward for improving crop yield and quality to ultimately enhance the structural integrity and consumer acceptance of sauerkraut. This study has broader applications for the nutritional content and crop yields of many organic crops that use conventional poultry and animal manures that may contain glyphosate in desiccated plant tissues or GE feeding operations. [ABSTRACT FROM AUTHOR]

Finding effective phosphorus (P) recommendation strategies to optimize corn (Zea mays L.) yield under varying yield levels and environmental conditions is continuously sought after. A 16‐year study was conducted in Concord, NE, on Nora silt loam soil initially measuring 16 ± 3 mg kg−1 Bray‐1 P. The study evaluated the impact of different P fertilization strategies on corn yield across various growing conditions (dry, normal, and wet years). Treatments included no P or N (NPNN), no P (NP), P applied at crop removal phosphorus (CRP), and maintaining soil P at 15 (B15), 30 (B30), and 45 (B45) mg kg−1 Bray‐1 P, with similar nitrogen (N) rates except for NPNN. Results showed a 25% and 33% reduction in soil test phosphorus (STP) for NPNN and NP treatments, respectively. The total P required by B30 and B45 treatments was 1.8 times more than that for CRP and B15. Although B30 and B45 treatments increased corn grain P concentration by 6%–12% compared to B15 and CRP, they did not increase yields in normal and dry years. The NP led to yield reductions of 9% and 12% in normal and wet years, respectively. In contrast, CRP achieved an 8% higher yield than B15 during wet years. Economic analysis revealed that B45 yielded a 56% higher net return in normal years, while CRP offered the highest return on investment (ROI) at 4.9. This study highlights the complexity of managing soil P under varying environmental conditions, emphasizing that while maintaining higher STP levels (B30 and B45) can enhance grain P concentration, it does not significantly boost yield and ROI compared to CRP and B15. Core Ideas: Applying P based on crop removal increases soil test phosphorus (STP) over time.Continued P application based on crop removal phosphorus (CRP) reduces yield loss risk compared to maintaining soil at critical level (15 ppm Bray‐1 P).High STP levels (>30 Bray‐1 P mg kg−1) increase grain P concentration and removal without consistent yield improvement.CRP‐based application maximizes net income and return on investment compared to maintaining soil at critical P levels. [ABSTRACT FROM AUTHOR]

Water erosion can be affected by land use change and soil degradation by agricultural activities. This study was conducted to investigate the effects of land use change in poor pastures on soil physical degradation and water erosion in semi-arid regions. Experiments were performed in 42 soil samples taken from seven areas covering the two land uses: poor pasture and rainfed agriculture, which have different soil textures (clay loam, silty clay loam, sandy clay loam, silt loam, loam, sandy loam, and sandy loam). The physical characteristics of soils were measured in the samples of both types of land use and its changes were expressed as physical degradation of the soil. The soil's susceptibility to water erosion was measured under simulated rainfall with 50 mm h-1 intensity for 60 min. The results showed that the land use change in pastures leads to the physical deterioration of soils; so bulk density, porosity, macropore, field capacity, saturated point, aggregate size, and aggregate stability were degraded with a rate of 28, 22, 41, 11, 5, 62, and 63 percentages. The structural characteristics of soil (aggregate size and stability) had the highest physical deterioration due to the land use change in the pastures. The change in land use change greatly increased the sensitivity of soils to water erosion. A significant relationship was found between the susceptibility of water erosion and the soil's physical degradation. The soils with coarser and more stable aggregates have higher physical degradation by the land use change and in consequence show more susceptibility to water erosion. [ABSTRACT FROM AUTHOR]

The use of clays for thermal treatments and cosmetic purposes continues to be a worldwide practice, whether through the preservation of native cultural traditions, pharmaceutical formulations or integrative health and well-being practices. Special clays, such as bentonites, are very common for healing applications due to their high cation exchange capacity (CEC), high specific surface area (SSA) and alkaline pH values and, therefore, are used in multiple therapeutic and dermocosmetic treatments. Numerous bentonitic deposits occur on Porto Santo Island with different chemical weathering degrees. This research evaluates which residual soils have the most suitable characteristics for pelotherapy. The texture of residual soils varies from silt loam to loamy sand and SSA between 39 and 90 m2/g. The pH is alkaline (8.7 to 9.6), electrical conductivity ranges from 242 to 972 µS/cm, and CEC from 50.4 to 86.8 µS/cm. The residual soils have a siliciclastic composition (41.36 to 54.02% SiO2), between 12.52 and 17.65% Al2O3 and between 52 and 82% smectite content, which are montmorillonite and nontronite. Specific heat capacity (0.5–0.9 J/g°C) and cooling kinetics (14.5–19 min) show that one residual soil has the potential to be suitable for pelotherapy according to the literature. Moreover, the residual soils have As, Cd, Co, Cr, Hg, Mn, Ni, Pb, Sb and V concentrations higher than the limits of guidelines for cosmetics and pharmaceutical products. [ABSTRACT FROM AUTHOR]

Agricultural intensification has increased the use of chemical fertilizers, promoting plant growth and crop yield. Excessive use of nitrogen fertilizers leads to nutrient loss and low nitrogen use efficiency. Management of nitrogen fertilizer input requires close to real‐time information about the soil nitrate concentration. While there is extensive work developing nitrate ion sensing solutions for liquid media, few allow for in‐soil measurements. This study introduces inkjet‐printed potentiometric sensors, containing 2 electrodes, the reference electrode (RE) and the nitrate‐selective film‐encapsulated working electrode (WE). The interaction between the nitrate‐sensitive membrane and soil nitrate ions causes a change in potential across the RE and WE. Additionally, a hydrophilic Polyvinylidene Fluoride (PVDF) layer ensures the long‐term functionality of the sensor in wet soil environments by protecting it from charged soil particles while simultaneously allowing water to flow from the soil toward the sensor electrodes. The sensors are tested in sand and silt loam soil, demonstrating their versatility across soil types. The potential change can be related to the nitrate concentration in soil, with typical sensitivities of 45–55 mV decade−1. Overall, the use of the PVDF layer allows for direct sensing in moist soil environments, which is critical for developing soil nitrate sensors. [ABSTRACT FROM AUTHOR]

The Soil Water Retention Curve (SWRC) is an essential input for modeling contaminant transport, irrigation scheduling, and other vadose zone soil–water processes. Measurement of SWRC requires instrumentation, skill, time, and cost. Alternatively, SWRC can be estimated from basic soil properties such as bulk density, particle size distribution (PSD), void ratio, plasticity index, etc., but the accuracy of estimates for varying soil textures remains largely unexplored. In this study, the performance of SWRC estimation models based on soil texture was analyzed for improved efficiency and application. Four samples (sand, silt, loam and clay) from the Unsaturated Soil Hydraulic Database (UNSODA) and two field soil samples (silt loam and sandy loam) from agricultural soils of Lower Himalayas were used in the study. Ten SWRC models were categorized and compared based on their applicability and efficiency. Overall, Fredlund and Xing (F&X) based models showed better performance in estimating SWRC for selected soil texture classes. Correlation analysis revealed a significant influence of soil texture class on model performance. Coefficient of variation (CV) showed that the wet region of SWRC was well captured by all models as compared to the dry region. Based on performance, SWRC models were ranked for respective soil texture classes and further evaluated for dry to saturated moisture conditions. Recommended models for respective soil texture classes can be used to estimate SWRC as per the availability of input soil properties, eliminating the need for complex experiments, thus saving considerable time and effort with acceptable accuracy. [ABSTRACT FROM AUTHOR]

Climate change has been intensifying soil drying and rewetting cycles, which can alter the soil microbiome structure and activity. Here we hypothesized that a soil drying-rewetting cycle enhances biodegradation and, hence, decreases the effectiveness of nitrification inhibitors (NIs). The effectiveness of DMPP (3,4-Dimethylpyrazole phosphate) and MP + TZ (3-Methylpyrazol and Triazol) was evaluated in 60-day incubation studies under a drying and rewetting cycle relative to constant low and high soil moisture conditions (40% and 80% water-holding capacity, WHC, respectively) in two different textured soils. The measurements included (i) daily and cumulative N2O-N emissions, (ii) soil NH4+-N and NO3−-N concentrations, and (iii) the composition of bacterial soil communities. Application of DMPP and MP + TZ reduced the overall N2O-N emissions under drying-rewetting (-45%), as well as under 40% WHC (-39%) and 80% WHC (-25%). DMPP retarded nitrification and decreased N2O-N release from the sandy and silt loam soils, while MP + TZ mitigated N2O-N production only from the silt loam soil. Unexpectedly, between days 30 and 60, N2O-N emissions from NI-treated soils increased by up to fivefold relative to the No-NI treatment in the silt loam soil at 80% WHC. Likewise, the relative abundance of the studied nitrifying bacteria indicated that the NIs had only short-term effectiveness in the silt loam soil. These results suggested that DMPP and MP + TZ might trigger high N2O-N release from fine-textured soil with constant high moisture after this short-term inhibitory effect. In conclusion, DMPP and MP + TZ effectively reduce N2O-N emissions under soil drying and rewetting. [ABSTRACT FROM AUTHOR]

Studying the process of soil erosion and evaluating its effective factors is one of the most important prerequisites for proper management of soil and water resources. This study was conducted to investigate the production of surface and pipe runoff and sediment using artificial rainfall on silt loam soil in the laboratory. So, the soil was collected from the study area and transported to the laboratory. Laboratory experiments were performed on a soil bed in a rectangular flume with three pipes, at slopes of 2%, 6%, 10%, 14%, and 18% under simulated rain (30 mm/h) for one hour. Related graphs were drawn in Excel to analyze the results, and Spearman's correlation test was used in SPSS software to check the correlation between runoff and sediment values in each slope. The results showed that with the increase in slope, the sum of surface and pipe runoff and sediment increased over time. For example, in a slope of 2%, the runoff and sediment in the initial moments of the experiment increased from 0 to 1.3 liters and 26.2 g m-2 at the end of the experiment. Also, the correlation coefficient between runoff and sediment in the slopes was 0.98, 0.62, 0.4, 0.93, and 0.15, respectively, which was significant in some, but in others, it was not significant because of soil loss. [ABSTRACT FROM AUTHOR]

Biochar can deliver many agronomic benefits, though effects may be greatest in suboptimal agricultural soils. The objective of this study was to investigate biochar in prime agricultural soils in a Mediterranean climate. In 3‐year irrigated processing tomato (Solanum lycopersicum) field trials, in which three biochars were amended to a sandy and silt loam, biochar did not influence yield. Given the global policy focus on biochar for climate change mitigation and adaptation, however, it is essential to measure more than just agronomic parameters. To this end, a soil health assessment was conducted 2.5 years after biochar amendment. In the fertile silt loam and more nutrient‐limited sandy loam, biochars had a variable but positive effect on pH, electrical conductivity, soil potassium, water stable aggregation, and permanganate oxidizable carbon. There was no effect on soil moisture nor potentially mineralizable nitrogen or carbon. In the silt loam, there was no change in microbial biomass or phospholipid fatty acid (PLFA) composition. In the sandy loam, almond shell biochars were associated with a slight increase in total biomass, an increase in the ratio of fungal to bacteria PLFAs, and reductions in multiple PLFA ratios were typically interpreted as indicators of environmental stress. Results of this study demonstrate that biochar may deliver soil health benefits in agricultural soils in a Mediterranean climate. However, increased soil health does not necessarily engender increased agricultural productivity within a 3‐year period. Furthermore, increases in soil health indicators were inconsistent across soil and biochar types, underscoring the need for site‐ and material‐specific investigation. Core Ideas: Climate policies may bolster biochar application to working lands, irrespective of soil texture or fertility.Data on potential agronomic and soil health outcomes are needed, particularly for prime agricultural soils.In 3‐year field trials, biochar did not positively or negatively impact processing tomato yield.Soil health indicators increased more in sandy loam than fertile silt loam, stressing need for site‐specific data.Incentives should cover biochar costs if no agronomic benefits are expected, and negative impacts are unlikely. [ABSTRACT FROM AUTHOR]

Conventional farming practices have negatively impacted micronutrient fertility and overall soil health. Metal lactates are an organic micronutrient amendment that provide both a labile carbon substrate as well as mineral nutrition for plant and microbial growth. To determine the ability of metal lactates to provide readily available micronutrients, Zn, Cu, Mn, Ni, and Co in lactate and chloride salt form were amended to soils and incubated for 28 days. Operationally defined speciation was determined using sequential extraction on samples incubated for 1, 5, or 28 days. The results show a comparable distribution of metals in chloride and lactate form; however, differences were detected in water‐soluble and exchangeable Ni and Zn at each timepoint. For example, in the water exchangeable fraction, there was 2.6%–2.9% less Ni and 0.2%–0.3% less Zn in the metal lactate‐treated soil compared to soil treated with metal chlorides. Furthermore, carbonate‐bound Ni averaged 4.1% and 4% less in metal lactate‐treated soils as compared to metal chloride‐treated soils on days 1 and 5, and Cu decreased 2.9%–3.3% during the treatment period for the lactate‐bound form. Additionally, microbial phospholipid fatty acid (PLFA) was performed and found a stimulatory effect of metal lactates on bacterial biomass with an increase of 12%–18% relative to the metal chloride treatment. Results from this study support the use of metal lactates as a sustainable alternative to conventional fertilizers by providing bioavailable micronutrients for plant nutrition in addition to a labile carbon source to support the growth of microbial populations. Core Ideas: Zn, Cu, Ni, and Co in lactate and chloride salt form have similar distribution in silt loam soil.Zn, Cu, and Ni supplied in chloride form were significantly more available than lactate forms.Metal lactates led to significantly greater bacterial and protozoan biomass compared to metal chlorides. [ABSTRACT FROM AUTHOR]

Classical soil aggregate stability (AS) methods lack standardized protocols and require long measurement times. However, the fairly new SLAKES method purportedly allows for rapid AS estimation with minimal technical equipment. SLAKES has been tested on fine‐textured soils but its suitability for other soil types is unknown. This study investigated SLAKES' suitability for AS measurements on silty clay, silt loam, and sandy loam soils. For each SLAKES test, three aggregates were immersed in distilled water and imaged for 10 min. SLAKES output includes disaggregation data per aggregate and three coefficients from a Gompertz function that describe slaking dynamics. Four AS descriptors obtained from SLAKES output were investigated: the averaged maximum slaking from a test (aSK), the maximum slaking for each measurement (aggregate) (aFT, from fitting a Gompertz function to SLAKES raw data), the averaged aFT for the measurements in a test (a̅FT), and the slaking index at 10 min per measurement (SI600). The aSK is a direct descriptor included in the SLAKES output, while aFT, a̅FT, and SI600 are indirect descriptors. The SI600 was the most preferred SLAKES AS descriptor since it is a calculated parameter and due to its sensitivity in detecting AS status among all soil types. The sandy loam soil was the most stable from both the raw SLAKES data and fitting, albeit counterintuitive. SLAKES default measurement time was sufficient for the silty clay and silt loam soils but not for the sandy loam soil. Overall, SLAKES was a useful tool for AS measurements on fine‐textured soils but was less suitable for AS measurements on the coarse‐textured soil. Core Ideas: We tested SLAKES suitability for aggregate stability measurements across diverse soil types.SLAKES sensitivity depends on the slaking descriptor employed.SLAKES was less suitable for the sandy loam soil but suitable for the silty clay and silt loam soils.The default measurement time was suitable for the finer soils but not for the coarse‐textured soils. [ABSTRACT FROM AUTHOR]

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Phosphorus (P) can be recovered from wastewater and used as an alternative fertilizer, namely, struvite [MgNH4PO4·6(H2O)]. However, the soil mobility of wastewater‐derived P and other nutrients needs to be evaluated. The objective of this study was to compare the vertical distribution of water‐soluble (WS) soil P and other nutrients from a synthetic‐wastewater‐derived electrochemically precipitated struvite (ECST) to that from a chemically precipitated struvite (CPST), triple superphosphate (TSP), monoammonium phosphate (MAP), and a control in six soils from Arkansas (AR; loam [L] and silt loam [SiL]), Missouri (MO; SiL 1 and SiL 2), and Nebraska (NE; sandy loam [SL] and SiL). A column‐leaching experiment was conducted with the six soils and five fertilizer‐P treatments. Water‐soluble (WS) P from the two struvite materials generally did not differ (p > 0.05) and was similar to that of MAP in the depths of 0–3, 3–6, and 6–10 cm, but was greater than that of TSP in the top 6 cm in four of the six soils. WS P from CPST in the MO‐SiL 2 and NE‐SL soils (6.6 and 12.7 mg kg−1, respectively) was larger than that from ECST, MAP, and TSP. In the AR‐L and MO‐SiL 1 soils, TSP was the only fertilizer‐P source that had increased WS P concentrations in the top 6 cm relative to the other fertilizer‐P sources. Results showed that ECST‐derived, WS P had similar soil profile distributions in the top 10 cm, suggesting that ECST will be equally protective of environmental health and leachate quality across multiple soil textures as other common fertilizer‐P sources. Core Ideas: Soil P from electrochemically precipitated struvite is not more mobile than that from other P fertilizers.Near‐surface soil pH and nutrient distributions are similar between struvite and other P fertilizers.Struvite appears to behave similar to other common fertilizer‐P sources across multiple soil textures. [ABSTRACT FROM AUTHOR]

Recent research has demonstrated the ability of a fenclorim seed treatment to reduce rice (Oryza sativa L.) injury to acetochlor. However, all studies were conducted on silt loam soils and have not evaluated rice tolerance or weed control on clay soils. Experiments were initiated in 2021 and 2022 at the Northeast Research and Extension Center near Keiser, AR, to determine rice response and the effectiveness of delayed‐preemergence (DPRE)‐applied microencapsulated (ME) acetochlor (1.1, 1.7, and 2.3 lb ai acre−1) when applied to a clay soil with and without a fenclorim seed treatment at 0 or 2.5 lb ai 1000‐lb−1 of seed. Averaged over the fenclorim seed treatment, acetochlor at 1.1 and 1.7 lb ai acre−1 caused similar injury levels to rice; however, barnyardgrass [Echinochloa crus‐galli (L.) P. Beauv.] control increased at 1.7 lb ai acre−1, eliciting 19% injury to rice and 82% barnyardgrass control at 28 days after emergence (DAE). Palmer amaranth (Amaranthus palmeri S. Watson) control ranged from 82% to 93%. Additionally, fenclorim did not influence barnyardgrass or Palmer amaranth control, but it did reduce rice injury and increase shoot density, plant height, and rough rice grain yield. At 14 and 28 DAE, fenclorim at 2.5 lb ai 1000‐lb−1 of seed (averaged over acetochlor rates) reduced visible rice injury from 61% to 13% and 40% to 8%, respectively. Results from this study indicate ME acetochlor could be successfully applied to rice grown on a clay soil when a fenclorim seed treatment is used, providing producers a new site of action for use in U.S. rice production. Plain Language Summary: Rice producers in the Southern United States need new effective herbicides to control problematic weeds. Research has shown that acetochlor (Warrant herbicide), while not labeled, could be used to control barnyardgrass in rice, but crop tolerance is a concern. Fenclorim has been used as an herbicide safener seed treatment to reduce rice injury to microencapsulated acetochlor, but this research was conducted on medium textured soils (silt loam). Rice tolerance has not been demonstrated on clay soils and heavier soils tend to bind more herbicide, which would mean higher rates are needed for adequate control. We observed good crop tolerance with acetochlor at 1.7 lb ai/acre (4.5 pt/A warrant) and a fenclorim seed treatment. This rate also demonstrated up to 82% barnyardgrass and Palmer amaranth control 28 days after the rice emerged. If a microencapsulated acetochlor were to become labeled in rice, producers could use it as an alternative residual herbicide option within a program. [ABSTRACT FROM AUTHOR]

Soil hydraulic and physical properties can be influenced by various land management practices, and they determine water movement and storage within the vadose zone, with both agronomic and environmental effects. The objective of this study was to evaluate the effects of two such practices (no‐till [NT] and cover crops [CCs]) on soil hydraulic (e.g., saturated hydraulic conductivity [Ksat], and water retention) and physical (e.g., bulk density [BD], pore size distribution, air‐filled pore spaces [AFPSs], and water‐filled pore spaces [WFPSs]) properties. The CCs used included crimson clover (Trifolium incarnatum L.), hairy vetch (Vicia villosa Roth.), winter peas (Lathyrus hirsutus L.), oats (Avena sativa), winter wheat (Triticum aestivum L.), triticale (Triticale hexaploide Lart.), flax (Linum usitassimum L.), and barley (Hordeum vulgare L.). Soil samples were collected and analyzed during 2021 and 2022 right before CC termination at 0‐ to 10‐cm, 10‐ to 20‐cm, and 20‐ to 30‐cm depths. Results showed that, during 2021 and 2022, BD was 18% and 14% higher, respectively, under NC compared with CC management, while Ksat was 2.2 and 1.9 times higher, respectively, under CC compared with NC management. Further, the non‐capillary pores were significantly (p ≥ 0.05) higher under CC compared with NC management during both years of study. As a result, the majority of the total pores under CCs were filled with air, while the majority of total pores under NC management were filled with water. Therefore, this CC mix may be useful in lengthening the growing period during wet seasons by increasing air‐filled pore spaces. Core Ideas: NT cover crops (CCs) significantly lowered BD and increased saturated hydraulic conductivity compared with no cover crop management.During 2 years, the van Genuchten α and n parameters were higher under CC management.CCs improved the proportion of capillary and non‐capillary pores.CCs increased the proportion of total pores filled with air.Under CC management alone, most soil properties were similar during 2 years. [ABSTRACT FROM AUTHOR]

Northern highbush blueberry (Vaccinium corymbosum L.) often requires frequent irrigation for commercial production, but irrigation is becoming increasingly challenging for many growers because of warmer and drier weather conditions, increased water regulations, and other water-use limitations. The purpose of this study was to develop improved methods of irrigation to prepare the industry more effectively against future water uncertainties. Treatments were applied for 2 years (2021 and 2022) and included a combination of weather-based or fixed irrigation schedules using continuous or pulse irrigation in a commercial field of ‘Draper’ blueberry in eastern Washington, USA. The soil at the site was a silt loam, and irrigation was applied using two laterals of drip tubing per row. Plants on a fixed schedule were irrigated for 12 to 13 hours per application (set by the grower), whereas those on a weather-based schedule were irrigated according to daily estimates of crop evapotranspiration (downloaded from an automated weather station). In both cases, irrigation was applied every 2 to 4 days as a single, continuous application or in 30- to 50-minute pulses every 2 hours (up to nine times per day) with the same amount of water as the continuous treatment. During the first year of the study, weather-based scheduling maintained greater stem water potentials in the plants and, on average, increased yield by 3.4 t·ha–1, berry weight by 0.14 g/berry, berry diameter by 0.4 mm, and fruit bud set by 4.3% when compared with fixed scheduling. Likewise, pulse irrigation maintained greater stem water potentials and, on average, increased berry weight and diameter by 0.10 g and 0.4 mm, respectively, fruit bud set by 3.3%, and canopy cover by 2.4% relative to continuous irrigation. Yield and canopy cover were unaffected by any treatment in the second year, which was likely a result of uncharacteristically cool, wet weather in the spring. However, weather-based scheduling continued to maintain greater stem water potentials and, when combined with pulse irrigation, increased berry weight and diameter by 3.7 g and 1.0 mm, respectively, relative to continuous irrigation on a fixed schedule. Pulse drip irrigation also increased fruit bud set by 5.1% during the second year. These results demonstrate the potential benefits of using weather-based scheduling and pulse drip in northern highbush blueberry, especially when the plants are grown on light-textured soils in hot, dry climates. [ABSTRACT FROM AUTHOR]

Major losses of agricultural production and soils are caused by erosion, which is especially pronounced on hillslopes due to specific hydrological processes and heterogeneity. Therefore, the aim of this study was to assess the impact of agricultural management on the compaction, infiltration, and seasonal water content dynamics of the hillslope. Measurements were made at the hilltop and footslope, i.e., soil water content and potential were measured using sensors, wick lysimeters were used to quantify water flux, while a mini-disk infiltrometer was used to measure the infiltration rate and calculate the unsaturated hydraulic conductivity (K_unsat). Soil texture showed differences between hillslope positions, i.e., at the hilltop after 50 cm depth, the soil is classified as silty clay loam, and from 75 cm onward, the soil is silty clay, while at the footslope, the soil is silt loam even at the deeper depths. The results show a higher K_unsat at the footslope as well as higher average water volumes collected in wick lysimeters compared to the hilltop. Average water volumes showed a statistically significant difference at p < 0.01 between the hilltop and the footslope. The soil water content and water potential sensors showed higher values at the footslope at all depths, i.e., 8.0% at 15 cm, 8.4% at 30 cm, and 27.3% at 45 cm. The results show that, even though the vineyard is located in a relatively small area, soil heterogeneity is present, affecting the water flow along the hillslope. This suggests the importance of observing water movement in the soil, especially today when facing extreme weather (e.g., short-term high-intensity rainfall events) in order to protect soil and water resources. [ABSTRACT FROM AUTHOR]

Accurate estimation of soil water content (SWC) is crucial for effective irrigation management and maximizing crop yields. Although dielectric property-based SWC measurements are widely used, their accuracy is still affected by soil variability, soil–sensor contact, and other factors, making the development of convenient and accurate soil-specific calibration methods a major challenge. This study aims to propose a plate compression filling technique for soil-specific calibrations and to monitor the extent of soil biomass degradation using dielectric properties. Before and after biodegradation, dielectric measurements of quartz sand and silt loam were made at seven different water contents with three different filling techniques. A third-order polynomial fitting equation explaining the dependence of the dielectric constant on the volumetric water content was obtained using the least-squares method. The suggested plate compression filling method has a maximum mean bias error (MBE) of less than 0.5%, according to experimental results. Depending on the water content, silt loam's dielectric characteristics change significantly before and after biodegradation. The best water content, measured in gravimetric units, to encourage the decomposition of biomass was discovered to be 24%. It has been demonstrated that the plate compression filling method serves as a simple, convenient, and accurate alternative to the uniform compaction method, while the dielectric method is a reliable indicator for evaluating biomass degradation. This exploration provides valuable insights into the complex relationship between SWC, biomass degradation, and soil dielectric properties. [ABSTRACT FROM AUTHOR]

The knowledge of the pattern of soil distribution and the characteristics are very essential for a better understanding, use and management of soils. It is with this background that the present study aims to characterize soil properties along toposequence in soil developed on sandstone parent material. The texture observed varied considerably, ranging from silty clay, clay loam, clay, silt clay loam, clay loam to silt loam. Bulk density had a mean value of 1.58 g/cm³, 1.61 g/cm³, and 1.15 g/cm³, in the crest, middle slope and valley slope soils. The soil was strongly acidic with pH in the crest, middle slope and valley bottom being 5.4, 5.35, and 5.4. The soil low in OC contents, all topographic positions had OC <1 %. The values of soil fertility indicators (organic carbon, total nitrogen, available P, exchangeable Ca, Mg, and K) were generally low. The findings further revealed that soil in the valley slope was better in quality than soils within the crest and middle slope. Cu had a mean value of 3.97 mg/kg, 2.17 mg/kg and 1.2 mg/kg in the crest, middle slope and valley slope soils, respectively. The values of Mn, Zn and Fe were above critical limit for deficiency. The values of estimated micronutrient indicated that the soils are safe for crop cultivation. Hence, to raise the productivity level of the present soil for optimum performance of crop, the management techniques such as continuous application of organic manure/crop residues to the soil, and use of low levels of chemical inputs should be put in place. [ABSTRACT FROM AUTHOR]

We developed a set of two precision, small-scale, water balance lysimeters to provide accurate measurements of bare soil evaporation. Each lysimeter comprises a soil tank, a balance assembly with load cell, a wicking drainage system, and a stilling well to measure drained water. Fiberglass wicks installed at the bottom of the soil tanks provide −60 cm of tension to the base of the soil column, and soil water drainage is quantified to close the water balance within the lysimeter. The calibrated lysimeters return mass changes with uncertainties ranging from 3 to 8 g, corresponding to uncertainties of 0.02–0.05 mm of water. Installed at a semi-arid site in northern Nevada, the two lysimeters are filled with uniform construction sand and silt loam. Over a six-month pilot observation period, bare soil evaporation rates of 0.19 and 0.40 mm/day were measured for the construction sand and silt loam, respectively, which is consistent with meteorological data and models of potential evapotranspiration at the site. The design of the lysimeter can be adapted to specific research goals or site restrictions, and these instruments can contribute significantly to our ability to close the soil water balance. [ABSTRACT FROM AUTHOR]

With climate change expected to intensify the occurrence and severity of droughts, the control of groundwater table (GWT) depth and capillary rise on topsoil moisture may render a critical driver of biological activity. Consequently, GWT depth could influence topsoil carbon mineralization. In this study, undisturbed 200 cm long soil columns of three different textures (loamy sand, sandy loam and silt loam) were subjected to two artificial GWT depths (–165 cm and –115 cm) in the laboratory. We examined (1) moisture supply by capillary rise along the soil profile and specifically into the top 20 cm soil, and (2) consequently the effect of GWT on decomposition of an added 13C-enriched substrate (ryegrass) over a period of ten weeks, with limited water applications representing a dry summer. A 50 cm difference in GWT depth (–165 cm vs. –115 cm) resulted in different topsoil moisture for the sandy loam (31 % vs. 38 % Water-filled pore space (WFPS)) and silt loam (33 % vs. 43 % WFPS) soils. In the loamy sand soil, GWT-induced moisture differences appeared only up to 85 cm above the GWT. The expected acceleration of mineralization of the added ryegrass under a shallower GWT was not confirmed. In contrast, C mineralization pulses after the wetting events were even higher for the drier –165 cm GWT soils. For the silt loam soil, where capillary rise supply had the largest contribution to topsoil moisture, a lower mineralization rate of the stable Cryegrass pool was also found with shallower GWT. These findings suggest that a potential capillary rise effect of increased topsoil moisture on ryegrass mineralization might have been counteracted by other processes. We postulate that the Birch effect might have been magnified following the rewetting of drier topsoils under deeper GWT levels, ultimately enhancing mineralization compared to where the soil remains consistently wetter under shallower GWT levels. Based on our findings, including the process of texture-specific capillary supply from the GWT can be required to adequately simulate moisture in the topsoil during droughts as they occurred over the past summers in North-West Europe, depending on GWT and texture combination. However, the net effect on topsoil C mineralization is complex and correct simulation of C mineralization may require further integration of specific processes connected to fluctuating soil moisture state, such as the Birch effect. [ABSTRACT FROM AUTHOR]

Conservation alternatives that include no-tillage (NT) and cover crops (CCs) reduce soil erosion in row-crop agroecosystems. However, little information is available about how these alternatives affect soil textural properties responsible for soil fertility. This study evaluated the soil particle size distribution and volumetric water content after three years of consistent management in a raised bed system. There were four treatment systems in a dryland maize/soybean rotation on a silt loam soil (Oxyaquic Fraglossudalfs) that included: NT + CCs, conventional tillage (CT) + CCs, CT + winter weeds, and CT + bare soil in winter in northwest Mississippi. The NT + CC system retained 62% more coarse sand in the furrow than the other systems (2.1% compared to 1.3%; p = 0.02). Regardless of the location, the NT + CC system (2.5%) retained 39% more fine sand than the CT + CC system (1.8%; p = 0.01), suggesting that coarse and fine sands were being trapped in furrows combining NT + CC systems, minimizing their off-site transport. In furrows, CCs increased soil volumetric water content by 47% compared to other winter covers. In beds, NT + CCs increased bed water contents by 20% compared to CT + CCs (17.1 to 14.3%; p < 0.01). Implementing conservation alternatives may promote the retention of sand fractions in silty loam soils that are important in supporting soil fertility and crop sustainability. [ABSTRACT FROM AUTHOR]

The proper amount of draft force required to till the soil is not coincide with the power applied in the field area during tillage of the soil. There is a need for investigation to predict the draft force of ard plow to improve our understanding of selecting appropriate input parameters for designing tools, which will help improve the allocation of the right prime power for a particular soil type. Otherwise, an excess load under load is applied and causes fatigue and inconvenience for both small-scale tools and operators. The aim of this research is to determine the draft force of Ard plough in silt loam soil. Laboratory and field tests were taken to measure actual draft force which was utilized as input for draft prediction. PI-Buckingham's pi theorem using dimensional analysis used to develop a mathematical model. IBM SPSS statistics software was applied to validate and verify the developed model. The relationship between the measured and predicted values of the draft force evaluated R 2 is 0.91. The predicted draft force value of skewness and kurtosis is in the range of accepted values. The performance of predicted draft force checked using RRMSE and CRM. Investigation findings demonstrate that derived mathematical equation was successful and viable for predicting the draft force of an ard plow in a silt loam soil. [ABSTRACT FROM AUTHOR]

Phosphate‐rich struvite (MgNH4PO4·6H2O) can be reclaimed from wastewater as a fertilizer material to help provide clean water and sustainable food production. The objective of this study was to evaluate the leaching characteristics of wastewater‐recovered electrochemically precipitated struvite (ECST) compared to other common fertilizer‐P sources in soils from Arkansas (AR loam and silt loam), Missouri (MO silt loam 1 and 2), and Nebraska (NE sandy loam and silt loam). A bench‐scale, soil‐column experiment was conducted using five fertilizer‐P sources (i.e., ECST, chemically precipitated struvite [CPST], monoammonium phosphate [MAP], triple superphosphate [TSP], and an unamended control [UC]) and leached six times over 15 weeks after fertilizer application. Leachate‐P concentration changes from the UC differed among soil–fertilizer combinations over time (p < 0.05) but only in the AR‐loam, where TSP (2.0–6.6 mg L−1) consistently had a larger leachate‐P change from the UC than ECST (−0.04 to 3.1 mg L−1) in weeks 1–3. Leachate‐NO3‐N concentration changes from the UC among soils occurred only in week 1, where three of the six soils had NO3‐N concentration increases >10.7 mg L−1 from their respective UC. Though inconsistent across the various soils evaluated, P‐leaching losses relative to respective UC treatments were often larger from MAP and TSP than ECST and CPST. Results showed that P, NH4‐N, NO3‐N, Ca, Mg, and Fe leaching potentials differed among soils depending on initial soil pH and texture and fertilizer‐P source; thus, soil characteristics and fertilizer‐P source should be considered to minimize potential nutrient leaching losses. Core Ideas: Phosphorus and nitrogen can be recovered from synthetic wastewater via electrochemical precipitation.Nutrient leaching from electrochemically precipitated struvite is comparable to other phosphorus fertilizers.Electrochemically precipitated struvite appears to be a viable alternative phosphorus fertilizer across textures. [ABSTRACT FROM AUTHOR]

Pulse irrigation, the practice of applying water in small doses over time, is known to reduce deep percolation and runoff and, relative to irrigating in single continuous applications, can increase plant growth and production by supplying water and nutrients at an optimal rate. The objective of the present study was to determine whether pulse irrigation was beneficial in red raspberry (Rubus idaeus L. 'Wakefield'). Treatments included continuous or pulse drip irrigation and were evaluated for three growing seasons (2018-20) in a commercial field with silt loam soil. Continuous irrigation was applied up to 4 hours/day, whereas pulse irrigation was programmed to run for 30 minutes every 2 hours, up to eight times/day, using the same amount of water as the continuous treatment. Pulsing improved soil water availability relative to continuous irrigation and, by the second and third year, increased fruit production by 1210 to 1230 kg·ha21, which, based on recent market prices, was equivalent to $2420 to $2460/ha per year. Much of this yield increase occurred during the latter 3 to 4 weeks of the harvest season and was primarily due to larger fruit size during the second year and more berries per plant during the third year. In 1 or both years, pulse irrigation also produced more canopy cover, larger cane diameters, and higher concentrations of Mg and S in the leaves than continuous irrigation, but it reduced K and B in the soil and had variable effects on sugar-to-acid ratio in the berries. On the basis of these results, pulsing appears to be an effective means of irrigating raspberry plants in sandy or silty loam soils, but more research is needed to determine whether it is useful technique in heavier soil types. [ABSTRACT FROM AUTHOR]

Crop growth and development is affected by intraspecies competition. This study was conducted to determine whether cotton productivity and profitability could be manipulated through planting geometry. The effects of row spacing, planting pattern, and variety on cotton fruit distribution, yield, and net returns were investigated near Bella Mina, AL, on a Decatur silt loam (fine, kaolinitic, thermic Rhodic Paleudults); Jackson, TN, on a Calhoun silt loam (fine‐silty, mixed, active, thermic Typic Glossaqualfs); Starkville, MS, on a Leeper silty clay loam (fine, smectitic, nonacid, thermic Vertic Epiaquepts); and Stoneville, MS, on a Bosket very fine sandy loam (fine‐loamy, mixed, active, thermic Mollic Hapludalfs). For both the 76‐ and 97‐cm row spacing, transitioning from a solid to a 2 × 1 skip row pattern reduced cotton lint yield by 19%. Reduced lint yield in the 2 × 1 skip row pattern was attributed primarily to a 7% decrease in the number of Zone 1 and first‐position bolls. Consequently, planting on a solid rather than skip row pattern increased net returns by 21%. Planting cotton in either 76‐ or 97‐cm rows using a solid rather than skip row pattern likely increases crop productivity and profitability across the US cotton belt. Core Ideas: Alternative cotton row spacings and patterns may improve net returns due to reduced input costs or greater yield.Regardless of row spacing, transitioning from a solid to 2 × 1 skip row pattern decreased cotton lint yield by 19%.Planting on a solid pattern rather than 2 × 1 skip row increased net returns by 21%. [ABSTRACT FROM AUTHOR]

Copyright of Irrigation & Drainage is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Substantial input of exogenous organic matter (EOM) may be required to offset the projected decline in soil organic carbon (SOC) stocks in croplands caused by global warming. However, information on the effectivity of EOM application dose in preserving SOC stocks is surprisingly limited. Therefore, we set up a 90-day incubation experiment with large soil volumes (sandy loam and silt loam) to compare the mineralization of EOM (13C-labelled ryegrass) and SOC as a function of three EOM application doses (0.5, 1.5, and 5 g dry matter kg-1 soil). In the sandy loam soil, the percentage of mineralized EOM was not affected by EOM dose, while SOC mineralization increased proportionally with increasing EOM dose (+49.6 mg C per g EOM). In the silt loam soil, the percentage of mineralized EOM decreased somewhat with increasing dose, while SOC mineralization increased at a higher rate than in the sandy loam soil (+117.2 mg C per g EOM). In both textured soils, increasing EOM dose possibly supplied energy for microbial growth and enzyme production, which in turn stimulated mineralization of native SOC (i.e. co-metabolism). Higher soil macroporosity at higher EOM doses in the silt loam soil could have contributed to sustaining aerobic conditions (indicated by soil Eh) and promoting SOC priming as shown by positive relationships between pore neck size classes 43–60, 60–100 and >300 μm and SOC priming, suggesting a new mechanism for understanding SOC priming. In sum, this experiment and our previous research suggest that EOM mineralization is mostly independent of EOM dose, but EOM dose modulates mineralization of native SOC. These findings tentatively indicate that using larger EOM doses could help preserve more of added EOM-C in silt loam soils, but longer-term confirmation in the field will firstly be required before we could draw any conclusion for soil C management. [ABSTRACT FROM AUTHOR]

Besides its carbon sequestration potential, biochar application generally improves soil physical properties, but the magnitude of its impact and the underlying mechanisms remain debated and depend on soil type, biochar application rate, and age. The objective was therefore to determine the effect of biochar application rate and age on physical properties of agricultural soils in a temperate climate. On a silt loam and a sandy loam soils, we compared the physical properties of fresh biochar (1% and 2% w/w) or century‐old biochar (0.5%–1% w/w; 19th‐century kiln sites)‐enriched soil samples with biochar‐free soil samples. Biochar pore network characteristics were determined using helium pycnometry, mercury intrusion porosimetry, scanning electron microscopy observation, and electron dispersive X‐ray spectrometry, whereas location of biochar particles within soil structure was analyzed using optical microscopy observations. Fresh biochar application decreased bulk density by 16.8% and increased saturated water content by 16.0% and macroporosity by 78.8%. These effects were attributed to soil structure improvement rather than to biochar porosity. Soil type and biochar application rate had a limited impact. In the long‐term, biochar effects were mostly nonsignificant, which might result from its fairly low content in kiln sites and from the clogging of its internal porosity by clay particles. Biochar was thus able to improve some soil physical properties in the short‐term, but these effects could no longer be detected in the very long‐term. Further investigating the time rate of change in soil physical properties over several decades following biochar additions to soil would therefore seem particularly relevant. Core Ideas: The effect of biochar age and concentration on soil physical properties was studied.Young biochar reduced bulk density and increased saturated water content and macroporosity.Biochar effects were attributed to soil structure improvement rather than to its internal pore characteristics.Century‐old biochar in kiln sites did not significantly affect soil physical properties.Soil type and biochar application rate impacted the results to a limited extent. [ABSTRACT FROM AUTHOR]

Biobased residues are local and cost-effective sources of soil amendments that can efficiently provide nutrients to crops, enhance soil health and serve as alternatives to mineral fertilizers. The objective of our study was to comprehensively evaluate the soil health and crop productivity of temperate agroecosystems amended with different types of organic residues (biobased residues), including composted food waste (compost), biosolid slurry (biosolids) and liquid anaerobic digestate (digestate), compared with nitrogen fertilizer. The experiment was conducted on a silt loam soil under maize-soybean rotation in Canada, where a wide range of physical, chemical and biological indicators were measured and integrated into a soil health score. Biobased residues resulted in about 50%-60% increase in soil-exchangeable potassium and 10% soil-exchangeable sodium over levels found in nitrogen fertilizer. Soil microbial biomass and the capacity of soil microbes to utilize carbon substrates differed among growing seasons but not among amendment types (p > .05). Crop productivity was similar among amendment types (p > .05). We found that the soil health score of biosolids was positively correlated with shoot and root biomass and negatively correlated with shoot nitrogen (p < .05), while that of nitrogen fertilizer was positively correlated with shoot carbon (p < .05). This was likely because of a variation in the availability of labile carbon and nitrogen among amendment types. Our research also suggests that temperate silt loam soil amended with biobased residues, especially biosolids, supplied sufficient nitrogen without the need for additional nitrogen fertilizer. [ABSTRACT FROM AUTHOR]

Copyright of Revista Intropica is the property of Revista Intropica and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

For developing mitigation methods to decrease or eliminate the risk of water contamination around crop areas, a thorough understanding of the leaching process is required. It also affects the efficacy of herbicides towards the target weeds. The study investigated the leaching of penoxsulam and bispyribac sodium in soils with varied physicochemical properties. Quantification was done using liquid chromatography tandem mass spectrometer. Penoxsulam was found to be moderately mobile and 86.3–90.2% of the applied herbicide was detected in soil column and residues in leachate were below the limit of quantification (0.008 µg mL−1). On the contrary, only 20.8–29.9% of the applied bispyribac sodium was detected in the soil columns and 62.8–87.12% was present in leachates. The highest leachability of penoxsulam and bispyribac sodium was found in loamy sand followed by sandy loam, loam, silt loam and clay loam. The results corroborated well with index-based leaching model using principal component analysis. Therefore, it is important to propose remediation method to avoid the potential adverse effect of herbicide behaving as leachar compound. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate the shear stress and deformation contribution of soil particle on silt loam and silt clay textural classes. The soil types of the study area are Hypereutric Vertisols and Rhodic Cambisols. Finite element method (ANSYS) was used to emphasize the locations and determine the amount of shear stress and deformation of soil particles, and IBM SPSS was used for analysis and verification of the results. The laboratory tests and fieldwork experiments were performed in order to determine the input data for finite element analysis. As a result, when draft forces of 615, 815, 1115, 1315, and 1515 N, the maximum shear stress created by clay soil particles is 4239.8 Pa, and the maximum deformation is 0.22 mm. The maximum shear stress in silt loam soil is found in silt soil particles (3713.6 Pa), and soil deformation was also created by silt soil particles (0.21 mm). The maximum shear stress in silt clay soil is found in clay soil particles (2247.09 Pa), and the maximum soil deformation is created by silt soil particles (0.10 mm). Level of fitness (R2) is 0.99%. This research is a great input for agricultural tillage tool designers and the farmers to develop effective design and maximum performance. [ABSTRACT FROM AUTHOR]

The application of biochar is considered to be a beneficial strategy for improving soil ecosystem services. The objectives of this study are to evaluate the differences in the soil erosion of silt loam soil with or without the application of biochar and to compare the impact of the application of biochar on soil erosion for different agricultural practices, namely, bare soil, silage corn, and sown peas. Specifically, the physically-based EROSION 3D model was used to estimate the soil erosion of small plots of sloping agricultural land. In considering various combinations of agricultural practices and rainfalls with different durations and intensities, several scenarios were used to assess the impact of the application of biochar on soil erosion. The results of this study demonstrate that the highest mean values of mean soil erosion in the case study area were simulated without using any biochar on bare soil. The values of the mean soil erosion were reduced with the use of biochar. The effect of the application of biochar was shown for all types of agricultural practices; above all, it reduced soil erosion that occurred above high values (over 30 t ha–1). Although the application and reapplication of biochar showed promise in reducing soil erosion, further research is needed to gain a deeper understanding of its total effects. [ABSTRACT FROM AUTHOR]

Domestic production of controlled-release, compost-based, and microbe-enhanced fertilizers is being expanded in the U.S. as a part of rural development. Sugarcane mill mud is a sterilized (≈90°C) agricultural byproduct in surplus that has received interests as a soil amendment in several Southern states, because of its high phosphorus and organic carbon contents. Addition of mill mud to sandy loam significantly increased the nodule formation compared to fertilized and unfertilized controls. Mill mud addition also resulted in pod yields similar to the fertilized control. Though not found in mill mud itself, mill mud additions correlated with an increase in soil Rhizobia as determined by deep 16S rRNA gene sequencing. We hypothesize that Firmicutes in sterilized mill mud induced Rhizobia that in turn enhanced soybean (Glycine max) growth. Collectively, mill mud enhanced the plant growth promoting bacteria when applied to a silt loam, although the relative influence of mill mud-derived bacteria, organic carbon, and nutrients is yet to be determined. [ABSTRACT FROM AUTHOR]

The present investigation was carried out in an on-going long-term fertilizer experiment, initiated during 1972 at experimental farm of Department of Soil Science, CSK HPKV Palampur, to study the long-term effect of fertilizers and amendments on soil aggregate stability and carbon dynamics in an acid Alfisol under maize-wheat cropping system. The experiment comprised of eleven treatments. The soil of the experimental site was silt loam and classified taxonomically as "Typic Hapludalf" (subgroup). Soil samples were collected from surface (0–0.15 m) layer after the harvest of wheat (rabi, 2019–2020) and were analyzed for different aggerate size and their carbon fractions. The addition of FYM enhanced the macroaggregates (>0.25 mm) as compared to microaggregates (<0.25 mm). Incorporation of FYM alone or in combination with chemical fertilizers enhanced the accumulation of different C pools in all aggregate fractions over unfertilized control. Among the macroaggregates, 1–0.5 mm fraction had higher total organic carbon (TOC), organic carbon (OC), labile carbon (LC) and non-labile carbon (NLC) as compared to microaggregates. Aggregate-associated carbon is less susceptible to physical, microbiological, and enzymatic degradation, and is a potential carbon reservoir that is protected from mineralization. Addition of FYM along with 100% NPK recorded highest SOC stocks, SOC sequestration rate and highest carbon buildup. Different aggregate fractions of TOC, OC, LC and NLC were found to be positively and significantly correlated with available N, P and K and negatively and significantly correlated with bulk density whereas, positively and non-significantly correlated with soil pH and electrical conductivity. Different aggregate fractions of TOC, OC, LC and NLC were positively and significantly correlated with grain and straw yield of wheat. [ABSTRACT FROM AUTHOR]

Arctic permafrost often contains gas-saturated horizons. The gas component in freezing and frozen soils can exist under different pressures, which are expected to affect their properties and behavior. The effect of pore gas pressure on the thermal conductivity of frozen and unfrozen silt loam saturated with methane or carbon dioxide at pressures below the hydrate formation conditions is observed in the current study. The variable gas pressure and temperature conditions are simulated in a specially designed pressure cell, which allows thermal conductivity measuring in pressurized samples at positive and negative temperatures. The experiments using natural samples collected near the gas emission crater (Yamal Peninsula) show that thermal conductivity is sensitive to pore gas pressure even at high moisture contents. The thermal conductivity of methane-saturated soil becomes 4% and 6% higher in frozen and unfrozen samples, respectively, as the gas pressure increases from 0.1 MPa to 2 MPa. In the case of CO2 saturation, the respective thermal conductivity increase in frozen and unfrozen samples reaches 25% and 15% upon pressure change from 0.1 to 0.9 MPa. The results stimulate further special studies of the effects of gas type and pressure on the thermal properties of closed gas-saturated taliks, of which the pore pressure is increasing during freezing up. [ABSTRACT FROM AUTHOR]

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There has been widespread interest in using compost to improve the hydrologic functions of degraded soils at construction sites for reducing runoff and increasing infiltration. The objective of this study was to determine the effects of compost amendment rate on saturated hydraulic conductivity (Ks) and water retention in order to identify target compost rates for enhancing soil hydrologic functions. Samples were prepared with three soil textures (sandy loam, silt loam, and sandy clay loam), amended with compost at 0%, 10%, 20%, 30%, 40%, and 50%. All soils were tested at a porosity of 0.5 m3/m3, and the sandy loam was further tested at high (0.55 m3/m3) and low (0.4 m3/m3) porosities. The Ks and water retention data were then used to model infiltration with HYDRUS‐1D. With increasing compost amendment rate, Ks and water retention of the mixtures generally increased at the medium porosity level, with more compost needed in heavier soils. As porosity decreased in the sandy loam soil, the amount of compost needed to improve Ks rose from 20% to 50%. Water distribution in pore fractions (gravitational, plant‐available, and unavailable water) depended on texture, with only the highest compost rates increasing plant‐available water in one soil. Results suggest soil texture should be taken into consideration when choosing a compost rate in order to achieve soil improvement goals. Hydrologic benefits may be limited even at a high rate of compost amendment if soil is compacted. [ABSTRACT FROM AUTHOR]

The use of urea as nitrogen (N) fertilizer in agriculture needs to consider environmental, economic and resource conservation aspects because of low N‐use efficiency (NUE). Polymer‐coated urea (PCU) offers an effective way to improve the NUE of urea and to reduce its environmental trade‐offs. However, we lack information on the impact of climate and soil properties on N release from PCU. Therefore, this study was performed to quantify the effects of soil texture, moisture and temperature on the release kinetics of N from PCU. We designed a test system for soil incubation experiments and investigated three fertilizers with different release patterns, five topsoils, three moisture levels and two temperatures over 48 days. We analysed the concentrations of inorganic N (NH4+−N and NO3−−N) in the soil and estimated N release rates using the unified Richards model. Soil texture did not change the N release patterns, but release rates varied significantly among the investigated soils. Changes in soil moisture for a given soil had no effect on N release from PCU and urea when fertilizers were incorporated into the soil at conditions supportive of crop growth. Lowering soil temperatures, however, decreased N release rates from PCU by 16%–49% but only in silt loam and not in sandy loam. We conclude that PCU improves the N residence time in soil, but predictions on N release from PCU must be adapted to the prevailing environmental conditions and cannot be generalized across differently textured soils. [ABSTRACT FROM AUTHOR]

The permeability coefficient and air-entry value of saturated soil are important hydraulic properties, which play an important role in engineering applications. Subsoil supporting foundation is subjected to stress and undergoes deformation; the saturated permeability coefficient of such deformed soil is of practical importance. With the help of fractal theory, based on the different fractal forms of Tao–Kong model, CCG model, Mualem model, and soil–water characteristic curve, this paper derives the saturated permeability coefficient models under four deformation conditions, considering the saturation permeability coefficient is inversely proportional to the square of the air-entry value and directly proportional to the square of the maximum aperture of the soil. Combining the prediction method of air-entry value under deformation conditions, four prediction methods for the permeability coefficient of deformed saturated soil are established and the method proposed in this paper is validated by the measured value of the saturated permeability coefficient of the deformed soil. As observed, the predicted values of the four methods for clay, silt loam, sandy loam and sandy soil under deformed conditions are in acceptable agreement with the measured values, and the prediction results of the second prediction method are the closest to the measured values. [ABSTRACT FROM AUTHOR]