Soil Application Research Articles

Anaerobic sludge from a full-scale biodigester: physico-chemical and organic characterization, and principal component analysis (PCA)

The biological transformation of the organic fraction of municipal solid waste into bioenergy yields a solid digested material known as anaerobic sludge, comprising a mixture of organic and inorganic substances. This sludge holds significant potential as a renewable resource for agricultural reuse. However, there is also the potential risk of contamination from this material in receiving environments. Therefore, it is crucial to assess the characteristics of this material to ensure compliance with local regulations regarding its soil application, aiming to avoid adverse environmental impacts and ensure proper and viable disposal. In this study, conducted to explore the characteristics of bottom sludge collected from a pilot-scale anaerobic biodigester, various parameters were analyzed. The biodigester in question had a capacity of 1300 liters and a useful volume of 1000 liters, digesting food waste and water hyacinth (Eichhornia crassipes) in a ratio of 20% in terms of volatile solids from the macrophyte to the volatile solids of the food waste. A multivariate analysis was conducted on the following parameters: metals (Al, Ba, Cd, Cr, Cu, Fe, Mn, Mo, Pb, Se, V, Zn, Na, and K); total, fixed, and volatile solids; alkalinity; volatile fatty acids; ammonia; Kjeldahl nitrogen (NTK); and organic, inorganic, and total carbon (COT), to observe possible correlations among these parameters. Additionally, the sludge underwent nuclear magnetic resonance (NMR) analysis for detection and characterization of organic compounds. This approach provided a deeper understanding of the properties of anaerobic sludge produced strictly under the aforementioned conditions, contributing to further research in the field.

Maximizing the value of liquid products and minimizing carbon loss in hydrothermal processing of biomass: an evolution from carbonization to humification

Hydrothermal carbonization (HTC) converts wet biomass into hydrochar and a process liquid, but aromatic compounds in the products have been reported as a roadblock for soil applications as they can inhibit germination, plant growth, and soil microbial activity. Here, we compared HTC and hydrothermal humification (HTH) of cow manure digestate while varying the initial alkaline content by adding KOH. HTH converted 37.5 wt% of the feedstock to artificial humic acids (A-HAs) found in both solid and liquid, twice that of HTC. HTH reduced phenolic and furanic aromatic compounds by over 70% in solids and 90% in liquids. The A-HAs in HTH resemble natural humic acids (N-HA), based on FTIR, UV–vis spectra, and CHN and XRD analysis. The HTH liquid possesses 60% higher total organic carbon (TOC) than HTC. Although one-third of TOC can be precipitated as A-HA, a high TOC concentration remains in the liquid, which is shown to be mainly organic acids. Therefore, we also evaluated the HTC and HTH liquids for anaerobic biomethane production, and found that compared to the original cow manure digestate, the HTH liquids increased methane yield by 110.3 to 158.6%, a significant enhancement relative to the 17.2% increase seen with HTC liquid. The strong reduction in organic acids during biogas production from HTH liquid indicates the potential for converting soluble byproducts into methane, while maintaining high A-HAs levels in the solid product.Graphical

Effect of Mulberry Stalk Biochar on Soil Nutrients Status and Productivity of Mulberry (Morus alba L.)

Biochar as an organic amendment improves soil attributes, with a potentially significant effect on soil fertility. The main objective of this study was to quantify the effect of biochar addition on nutrients status in mulberry cultivated soil. A field experiment was conducted in the mulberry crop to know the effect of soil application of mulberry stalk biochar on nutrients build up in soil at farmer’s field at Sidlaghatta (TQ), Chikkaballapura District during 2020-2021 (rabi2020, summer and kharif-2021). A randomized block design was employed with eight treatments replicated thrice T1: Control (NPK375:140:140 kg ha-1 alone) T2: POP (FYM (25 t ha-1) + NPK 375:140:140 kg ha-1) T3: Soil application of biochar @ 5 t ha-1T4: Soil application of biochar @ 7.5 t ha-1 T5: Soil application of biochar @ 10 t ha-1T6: Soil application of biochar @ 5 t ha-1 + FYM @ 10 t ha-1T7: Soil application of biochar @7.5 t ha-1 + FYM @ 10 t ha-1T8: Soil application of biochar @ 10 t ha-1 + FYM @ 10 t ha-1NPK is common for all the treatments. Combined soil application of biochar @ 10 t ha-1 and FYM @ 10 t ha-1 (T8) increased the leaf yield (13.07 t ha-1) by 21 % over control (10.45 t ha-1 Significantly higher soil primary, secondary and micronutrients were recorded in T8 (soil application of biochar @ 10 t ha-1 + FYM @ 10 t ha-1) followed by treatment T7 which received soil application of biochar @ 7.5 t ha-1 + FYM @ 10 t ha-1. The lower soil primary, secondary and micronutrients were recorded in T1 which is devoid of biochar. The findings revealed that utilization of mulberry stalk as a biochar has positive effect on the improvement of nutrient status and it could partly replace chemical fertilizers and promote organic farming in a circular economy concept.

Biofortification of wheat in salt-affected soil through seed priming and soil application of zinc

ContextGiven the global significance of wheat production and consumption, it is imperative to achieve high yields of nutritious wheat grains. However, the inadequate availability of zinc (Zn) in salt-affected soils can aggravate salt stress, decrease wheat grain yield, and grain Zn concentration. This study compared the effectiveness of soil Zn application and seed Zn priming in increasing Zn biofortification and grain yield of Zn-biofortified wheat grown in alkaline-calcareous soil affected by salts. MethodsEighteen pots were filled with alkaline-calcareous soil containing elevated levels of soluble salts and exchangeable sodium (Na). The pots were subjected to soil Zn application (0 or 8 mg kg−1) and seed priming (control/non-, hydro-, or Zn-primed seeds) treatments, applied to a Zn-biofortified wheat (cv. Zincol-2016). Plant samples were collected at the heading and maturity stages to measure parameters related to plant growth and grain quality. FindingsSoil Zn application increased grain and straw yields across seed priming treatments by a maximum of 23 %, and seed Zn priming increased grain and straw yields across soil Zn rates by a maximum of 21 %. This yield response was accompanied by significant increases in grain potassium and Zn concentrations at maturity, as well as non-significant to significant increases in photosynthetic parameters (stomatal conductance, photosynthetic rate and transpiration rate) in flag leaves during heading. Additionally, compared to control, the combined treatment of soil Zn application and seed Zn priming decreased grain Na concentration by 14 %. Compared to control, both soil Zn application and seed Zn priming significantly increased grain Zn concentration. With the combined application treatment, the grain Zn concentration reached 27 mg kg−1, but it remained significantly below the desired level of >37 mg kg−1. Seed Zn priming decreased the phytate-to-Zn molar ratio in grains, while the treatments that received soil Zn application exhibited the lowest values of this ratio, potentially increasing Zn bioavailability to humans. ConclusionsThe findings suggest that soil Zn application is more effective in enhancing grain yield and Zn concentration, while seed Zn priming remains crucial in low-Zn and high-salt soils. Future research should optimize Zn application strategies for Zn-biofortified wheat cultivated in salt-affected fields.

Biochar – a sustainable soil conditioner for improving soil health, crop production and environment under changing climate: a review

Land degradation and climate change, two intricately intertwined phenomena, demand appropriate management solutions to effectively tackle the escalating issues of food and nutritional security. In this context, the realm of agriculture confronts formidable challenges in its pursuit of soil resource reclamation, improving water quality, mitigating climate change, and maintaining soil and natural resources for posterity. Central to these aspirations is the preservation of an optimum organic matter, serving as a linchpin threshold is crucial for protecting the physical, chemical, and biological integrity of the soil, while simultaneously sustaining agricultural productivity. To address these multifaceted challenges, the introduction of diverse organic amendments has emerged as a crucial strategy. Noteworthy among these is the application of biochar, which functions as a soil conditioner capable of bolstering soil health, mitigating the impact of climate change, and securing global food security. Biochar is a carbon-enriched substance produced through pyrolysis of assorted biomass waste. It has a larger surface area, higher cation exchange capacity, and an extended carbon storage capability. The strategic integration of biochar production and subsequent soil application engenders an array of benefits, encompassing the amelioration of soil physical properties, augmented retention and the availability of nutrients, and the enhancement of biological activity, resulting in higher agricultural yields and societal benefits through the curtailment of soil to atmosphere greenhouse gas emissions. Additionally, biochar demonstrates its efficacy in the realm of environmental restoration by serving as a medium for extraction and elimination of heavy metals, which often pervade aquatic ecosystems and soil matrices. This review addressed the need for biochar production, characterization, soil health, the possibility for environmental restoration, and crop yield fluctuations owing to climate change.

Application of Termite Mound-Bentonite Mixture as Bottom Liner for Industrial Waste Containment

The indiscriminate disposal of waste into various dumpsites with noncompliance to the existing environmental laws and the inadequate provision for leachate containments had resulted in the degradation of environmental resources over the years. The research investigated the practicability of enhanced termite mound-bentonite mixture as an alternate landfill bottom liner. The percentage weight ratio of mound soil and bentonite used for the experimental study were (100:0), (95:5), (90:10) and (85:15) respectively. The study was conducted on a pilot scale artificial landfill (800 x 800 x 400 mm) with four sections AX, AY, BX and BY. Bottom liner was exposed to wastewater for 26 weeks retention period. The pilot scale experimental study revealed that liner mixtures in sections AX, AY and BX failed during the 6, 11 and 17th week retention periods respectively with a corresponding seepage amounting to , and mm3 respectively. However, no seepage was recorded for liner mixture in section BY which connotes that wastewater leakage was prevented throughout the experimental framework. Conclusively, the application of termite mound soil enhanced with 15% bentonite is recommended as a bottom liner in a waste containment system.

Enhancing nutrient uptake and grapefruit (Citrus paradisi) growth through soil application of beneficial bacteria (Bacillus spp.)

The term plant growth-promoting rhizobacteria (PGPR) refers to a root-associated bacteria that possesses several benefits for soil and the plant. The increasing demand for sustainable food production necessitates a shift towards agricultural practices that mitigate adverse environmental impacts. Excessive use of chemical fertilizers and pesticides has raised concerns, prompting a surge of interest in harnessing the potential of beneficial soil microorganisms, particularly plant growth-promoting rhizobacteria. This study explores the impact of soil inoculation with PGPR treatments on grapefruit seedlings, including a commercial strain of Bacillus velezensis, a fresh inoculum of Bacillus amyloliquefaciens, a mixture of three selected citrus endophytic Bacillus spp. isolates, inorganic fertilizers, and combinations thereof. The aim was to test their ability to enhance growth and nutrient uptake reducing the input of chemical fertilization. Results indicated that the combination of Bacillus velezensis and inorganic fertilization significantly improved soil nutrient availability and enhanced plant growth, surpassing both negative (water) and positive (inorganic fertilization) controls. Shoot and root system biomass showed significant increases from Bacillus velezensis plus inorganic fertilization compared to other treatments. These findings provide insights into management methods that can reduce chemical inputs while promoting plant productivity. The demonstrated benefits of PGPR on grapefruit seedlings highlight a promising approach for future research and applications in sustainable citrus cultivation.

Endophytic bacteria nano-formula: A promotor for plant growth and systemic acquired resistance against sheath blight disease on rice

Sheath blight disease significantly affected growing rice crop and caused yield losses. This study identified two endophyte bacterial isolates, Bacillus subtilis, and Pseudomonas brassicacearum subsp. Neoaurantiaca, significantly inhibit Rhizoctonia solani AG1 IA mycelial growth. Further, the analysis of the culture filtrate for the two identified bacteria recorded a set of bioactive components that have antifungal activity and enhance plant growth. We prepared a novel nano-formula using the advantages of nano natural charcoal (NCNPs) as an organic matter and enriched with alginate to improve the nano-formula porosity and keep the viability of the loaded bacteria up to 18 months. Two methods (soil application and root dipping) were used to evaluate the impact of bacteria nano-formula on rice growth and rice sheath blight (ShB) disease under artificial inoculation with R. solani at greenhouse conditions. The root dipping with P. brassicacearum NCNPs alginate (PBNF-R) and B. subtillus NCNPs alginate (BSNF-R) recorded the highest performance in the rice growth traits, and a high control level of the rice ShB disease by decreasing relative lesion height and percent disease index. In addition, PBNF-R and BSNF-R increase the defense-related enzyme production in the plant cell (peroxidase, polyphenol oxidase, and phenylalanine ammonia‐lyase) and, consequently, the plant immunity. Moreover, both upregulate the gene expression levels of OsNPR1, OsWRKY45, OsPR10, and OsAOS2, which are related to the plant defense mechanism. Finally, here we introduce the first application of bacteria nano-formula as a safe environmental approach to control the rice ShB disease, promoting growth and thousand-grain weight in rice.

Applying Boron by Fertigation or as a Foliar Fertilizer Is More Effective than Soil Applications in Northern Highbush Blueberry

Boron (B) is often deficient in many fruit crops, including blueberry (Vaccinium sp.). The objective of the present study was to evaluate different methods for applying B fertilizers to two commercial cultivars of northern highbush blueberry (V. corymbosum Earliblue and Aurora) in western Oregon, USA. Treatments included soil application of sodium tetraborate in early April (before bloom), foliar application of boric acid in late April (during bloom or petal fall), weekly fertigation with boric acid from April through July, and a control with no B. The plants were irrigated by drip, and the fertilizers were applied for two consecutive seasons at a total rate of 1.5 kg·ha−1 B per year. Each method of fertilizer application increased the concentration of B in the soil solution relative to the control, but fertigation was the only treatment that increased extractable soil B to the recommended level of 0.5 to 1.0 mg·kg−1 B. In terms of plant nutrition, foliar application of B was the most effective method for increasing the concentration of B in the leaves, roots, and fruit, followed by fertigation. Soil application of B, on the other hand, was relatively ineffective and, after 2 years, only increased the concentration of B in the leaves of ‘Earliblue’. Although leaf B levels were initially deficient at the site (<30 ppm B), none of the B application methods had any effect on yield, berry weight, fruit firmness, or titratable acidity of the fruit in either cultivar. However, foliar applied B resulted in higher concentrations of soluble solids in the fruit than no B or soil applied B in ‘Earliblue’, whereas B fertigation resulted in higher concentrations of soluble solids than soil applied B in ‘Aurora’. On the basis of these results, applying B by fertigation or as a foliar spray is recommended over the use of soil applications of B fertilizer in northern highbush blueberry.

A Comprehensive Review of the Evaluation and Application of Engineering Properties of Expansive Soil Based on Piezocone Penetration Test (CPTU)

Expansive soil presents several challenges in civil and geotechnical engineering because of its distinctive physical and mechanical properties, including considerable volumetric fluctuations, non-linear stress–strain behaviour, and high permeability. Owing to soil disturbances and sample size limitations during sampling, important parameters such as the expansive soil expansion force, compressive strength, and shear strength obtained through indoor experiments often cannot accurately reflect the values in situ. In this regard, in situ piezocone penetration testing has the advantages of small disturbances and high efficiency and has been widely used in subways, bridges, highways, and other engineering projects. This paper comprehensively summarizes the research progress of in situ testing technology in the evaluation and application of engineering properties of expansive soils in China and internationally. First, a detailed analysis of the basic theories and physical mechanisms of various in situ testing methods is provided, focusing on their applicability and accuracy in expansive soils. Second, examples of the application of in situ testing technology in expansive soil engineering are summarized. Finally, predictive models and methods based on in situ testing data, especially those that introduce cutting-edge models such as machine learning and advanced data analysis techniques, are discussed.

The trade-off regulation of arbuscular mycorrhiza on alfalfa growth dose-dependent on gradient Mo exposure

Molybdenum (Mo) is an essential nutrient for leguminous plants, but the effects of Mo exposure on plant growth, especially in relation to soil microorganisms, are not fully understood. This study employed alfalfa (Medicago sativa L.) to evaluate the physiochemical responses to gradient soil Mo variations and explore the potential regulatory role of rhizosphere microorganism - arbuscular mycorrhizal fungi (AMF) in modulating Mo's impact on plant physiology, with a focus on metabolic pathways. The results showed that Mo exerted hormetic effect (facilitation at low doses; inhibition at high doses) on alfalfa growth, promoting biomass (below 90.94 mg/kg, with a 63.98 % maximum increase), root length (below 657.11 mg/kg, with a 39.29 % maximum increase), and plant height (below 304.03 mg/kg, with an 18.4 % maximum increase). Excess Mo (1000 mg/kg) resulted in a reduction in photosynthesis and biomass growth due to increased oxidative stress (p < 0.05). Within the stimulatory zones, AMF enhanced Mo accumulation in alfalfa, augmenting its phytological effects. Exceed the stimulatory zones, AMF enhanced alfalfa Fe uptake and reduced the generation of reactive oxygen species (ROS) induced by excess Mo by shifting the redox homeostasis-controlled enzyme from peroxidase (POD) to superoxide dismutase (SOD), thereby improving alfalfa's tolerance to Mo. Metabolomic analysis further revealed that AMF promoted the biosynthesis of indole acetic acid (IAA) and various amino acids in Mo-stressed alfalfa (p < 0.05), which accelerated alfalfa growth and mitigated Mo-induced phytotoxicity. These insights provide a foundation for developing sustainable management strategies for Mo-exposed soils using AMF inoculants, such as minimizing Mo fertilizer application in Mo-deficient soils and facilitating the reclamation of Mo-contaminated soils.

Evaluating micronutrients effects on yield and quality attributes of chrysanthemum (Dendrathemum Grandiflorum Tzeuleu) cv.CO1

The field experiment was conducted in the Department of Horticulture, Faculty of Agriculture, Annamalai University, and Tamil Nadu in chrysanthemum (Dendrathemum grandiflorum Tzeuleu) cv.CO 1. The experimental site situated approximately 6 km west of the Bay of Bengal, positioned at 11o 24' North latitude and 79o 41' East longitude, with an altitude of +5.79 meters above mean sea level. The maximum mean temperature range from 29.7ºC to 38.3ºCwith a mean of 32.4ºC, while the minimum temperature range from 21.10ºC to 27.0ºC with a mean value of 25.3ºC. Its receives an annual rainfall of 1500 mm with a relative humidity of 85%. From the results, it can be concluded that soil application of micronutrients mixture @12.5 kg ha-1 in split as basal, 25, 50 and 75 DAT was found to have beneficial effect on yield and quality attributes of chrysanthemum.

Fungicidal control of onion pink root caused by Setophoma terrestris and effects on soil enzyme activity

AbstractPink root disease (PRD) caused by Setophoma terrestris is a major disease in onion‐producing regions. The fungus primarily infects onion, but occasionally causes disease on other plant species such as cereals, corn, cucurbits, pepper, spinach, and soybean. In this study, we analysed the efficacy of three commercially available fungicides at low dose in two successive years (2020–2021) in the field. These included Priaxor Xemium Brand (fluxapyroxad + pyraclostrobin) at 1.0 or 1.5 L/ha, Lamardor 400 FS (propiconazole + tebuconazole) at 2.5 kg/ha, and Rovral TS (iprodione) at 5.0 kg/ha applied via soil surface irrigation, and also Priaxor as foliar application (1.0 L/ha) against PRD on three onion cultivars: white, red, and yellow. All fungicides were applied thrice within 3‐week intervals from the onset of PRD (mid‐February), and fungicidal efficacy was determined 2 weeks prior to harvest (mid‐May). The lowest PRD severity was recorded for Priaxor 1.5 L/ha at 9.5%, followed by Lamardo at 10.1%, and the remaining treatments compared with the untreated control at 47.7% severity. The highest production (per 100 bulbs) was recorded for Priaxor 1.5 L/ha with 7.36 kg, followed by Lamardo with 6.86 kg and the remaining treatments compared with untreated at 4.33 kg. When treatment effects on soil enzymes were examined prior to harvest, there was no substantial change in urease activity, whereas soil application of Priaxor increased alkaline phosphatase activity by 50% and decreased acidic phosphatase by 42% compared with the untreated control. Our data indicated that fungicides have subtle differences in efficacy profiles, which may translate to improved management against PRD.

Partial substitution of manure increases N2O emissions in the alkaline soil but not acidic soils

The fertilization regimes of combining manure with synthetic fertilizer are benefits for crop yields and soil fertility in cropping systems as compared to sole synthetic fertilization, but the responses of nitrous oxide (N2O) emissions to these practices are inconsistent in the literatures. We hypothesized that it is caused by different proportions of nitrogen (N) applied as manure and various soil properties. Here, we conducted a microcosm experiment, and measured the N2O emissions from control (no N) and five manure substitution treatments (supplied 100 mg N kg−1 using the combination of urea with manure) with a range of proportions of N applied as manure (0, 25%, 50%, 75%, and 100%) in three different soil types (fluvo-aquic soil, black soil, and latosol) under aerobic condition. The stimulated effect on N2O emissions was more pronounced after manure application in an alkaline soil with high nitrification rate, due to relatively rapid soil DOC depletion and N mineralization of manure. N2O emissions from partial substitution of urea with manure were significantly higher than manure-only addition under high soil pH due to abundant labile C from manure. However, there was no difference between manure substitution treatments under acid soils. Nitrification inhibitor substantially decreased N2O emissions with increasing soil pH, but it was less effective in mitigating N2O emissions with larger proportion of manure. This is likely due to the slow nitrification under low soil pH, and denitrification derived N2O increased with increasing manure application rate. Collectively, our study shows that the application of manure substitution to alkaline soils requires careful consideration, which might have rapid nitrification potential and hence trigger significant N2O emissions. The knowledge gained in this work will help the decision-makers in optimizing a sound N fertilization regime interacted with soil properties for sustainable crop production and N2O mitigation.

Study on Effect of Bio Control Agent Trichoderma viride and Neem Cake on Rhizome Rot of Turmeric

Turmeric (Curcuma longa) is one of the major spice crops in Andhra Pradesh, which is severely affected by rhizome rot (soil borne disease) and leaf spots (foliar diseases). There was drastic reduction in yield, which is majorly affected by soil borne fungus. So, the present study mainly intends to evaluate the performance of Trichoderma viride along with neem cake against rhizome rot disease. The experiment was conducted in three successive years at 10 villages and 30 locations of Krishna district as a Front-Line Demonstration of Krishi Vigyan Kendra, Ghantasala, Acarya N G Ranga Agricultural University. The treatment (TO1) consists of seed treatment, ridge sowing, excess water drainage and soil application of T viride culture 2 kg multiplied in 90 kg Farm Yard Manure and 10 kg neem cake at the last ploughing time and use of neem cake 300 kg/acre at 60 and 120 DAP at plant base. Whereas, the farmer’s practice (TO2) was drenching of copper oxy chloride @ 3g /l of water only to control rhizome rot. In comparing the average data of both the treatments for three consecutive years, TO1 recorded highest yield of 49.12 t/ha of fresh turmeric with a yield improvement of 32.43 % over control. In case of rhizome rot incidence, the average percent incidence for the three consecutive years was reported as 3.37 % in demo and 10.72% in control. In case of net returns, Rs. 2,08,743/- per ha was obtained with a B:C ratio of 1.99:1 in demo and Rs. 93,428.17/- of per ha with 1.43:1 B:C ratio in control. It can be concluded that apart from using only chemicals, integrated management practices fetch better yield and returns too.

Interplay between green-synthesized nanoparticles and plant performance is mediated by the microbial community in the rhizocompartments

Numerous green-synthesized nanoparticles are being evaluated for their potential application in soil, yet understanding their influence on plant performance and their rhizocompartments associated microbes is a gap that needs to be addressed. In this study, we investigated how applying iron oxide nanoparticles (control 0, low 25 and high 50 mg/kg) impacted the rhizocompartments associated microbial communities and plant secondary metabolites grown in natural soil microcosm. The transcriptional analysis showed that the majority of artemisinin and flavonoid biosynthetic pathway genes were significantly upregulated in plants with the application of low concentration of green-synthesized iron oxide nanoparticles (FeO.NPs) when compared with control plants, suggesting a fine collaboration between these metabolites’ pathways, as indicated by a remarkable increase in artemisinin content (2-fold), ferulic acid (7.6-fold), luteolin (4.3-fold) and syringic acid (6.2-fold). The response of rhizocompartments microbial communities and associated soil enzymes was investigated using high-throughput sequencing and profiler test kits, respectively. The soil microbial community structure was altered upon FeO.NPs exposure in both low and high treated soils as indicated by multivariate analysis. For instance, bacterial phyla Bacteroidetes and Gemmatimonadetes and fungal phyla Ascomycota demonstrated a significant rise in relative abundance in both the rhizosphere and rhizoplane in low and high treatments relative to the control. Moreover, genera level analysis revealed that Cupriavidus, Vibrionimonas, and Burkholderia displayed higher relative abundance (p < 0.05) in low FeO.NPs concentration while Giaella and Nonomuraea didn't show any noticeable response to FeO.NPs. In terms of fungal genera, Oidiodendron and Cryptococcus showed high relative abundance under low treatment. The altered microbiome profile is possibly associated with soil enzymes, for instance, urease and catalase activities were increased by 1.76 and 1.71-fold, respectively in low FeO.NPs. Thus, this study demonstrates the effects of FeO.NPs gradients on plant secondary metabolites and soil enzyme activities, while contributing new insights into their specific impacts on the microbial community composition in the rhizocompartments of plant root system.

Integrated foliar application of potassium with soil applied nitrogen and phosphorus improves productivity of chickpea (Cicer arietinum L.)

Optimal nitrogen and phosphorus fertilization can enhance growth and yield of chickpea. However, little is known on nitrogen and phosphorus fertilization supplemented with foliar application of potassium on productivity of chickpea. Therefore, a study was designed with the aim to explore–efficiency of soil applied nitrogen and phosphorus in combination with foliar potassium nutrition on performance of chickpea. The chickpea cultivar Bittle-98 was grown in plastic pots filled with 10 kg of soil following Randomized Complete Design (RCBD). Various treatments comprising control (T1), nitrogen 160mg/pot (T2), phosphorus 385mg/pot (T3), nitrogen 160mg/pot + 0.75% K2SO4 foliar (T4), phosphorus 385mg/pot +0.75% K2SO4 foliar (T5), and nitrogen 160mg/pot + phosphorus 385mg/pot+0.75% K2SO4 foliar (T6) were tested. The T6 resulted in maximum plant height (64.37cm), number of pods per plant (45.46), seeds per pod (1.40) 100-seed weight (18.03g), SPAD counts (34.52), seed yield (35.80g/pot), and biological yield (85.24g/pot) than rest of the treatments. The yield in response to T3 was significantly higher than T2, mainly because of higher pods frequency, indicating that phosphorus is more imperative than nitrogen to harvest maximum yield of chickpea. The yield obtained was in the order of T6&gt;T5&gt;T4&gt;T3&gt;T2. It is revealed that soil applied nitrogen plus phosphorus supplemented with foliar potassium is an effective strategy to harvest higher yield of chickpea. Recommended soil application of nitrogen and phosphorus with foliar 0.5% K2SO4 is suggested to harvest maximum yield of chickpea.

Combining Zinc Biofortification and Native Trichoderma Inoculation Strategies for Subterranean Clover

Using beneficial microorganisms along with sustainable strategies such as agronomic biofortification offers eco-friendly alternatives to combat climate change in ecosystems like dehesas. This study analyzes the combined effects of four wild Trichoderma spp. isolated from Extremadura, Spain (T. koningiopsis, two T. gamsii, and T. koningii, with negative and positive controls) and four Zn biofortification treatments (no Zn application; soil application of 5 mg of ZnSO4·7H2O per kg of soil, labeled soil Zn; two foliar applications of 5 mL 0.5% ZnSO4·7H2O, labeled foliar Zn; and soil + foliar combination, labeled SF) on Trifolium subterraneum performance. The combination of T. koningiopsis and T. gamsii with foliar Zn improved plant growth by up to 34.4%. Zinc accumulation was about 30% higher when T. gamsii and T. koningii were applied with SF, and their inoculation resulted in a 2.5-fold increase in ash. Trichoderma spp. affected nodulation differently; both T. gamsii inhibited nodulation by 24%, whereas neither T. koningiopsis nor T. koningii showed differences from the controls. These results highlight the potential of combining beneficial microorganisms with biofortification strategies to address nutrient deficiencies and improve agricultural sustainability. However, the complex interactions between both factors underscore the importance of strain selection and call for further research to optimize application strategies and elucidate underlying mechanisms.

Large-scale soil application of hydrochar: Reducing its polycyclic aromatic hydrocarbon content and toxicity by heating

The beneficial roles of hydrochar in carbon sequestration and soil improvement are widely accepted. Despite few available reports regarding polycyclic aromatic hydrocarbons (PAHs) generated during preparation, their potential negative impacts on ecosystems remain a concern. A heating treatment method was employed in this study for rapidly removing PAHs and reducing the toxicity of corn stover-based hydrochar (CHC). The result showed total PAHs content (∑PAH) decreased and then sharply increased within the temperature range from 150 °C to 400 °C. The ∑PAH and related toxicity in CHC decreased by more than 80% under 200 °C heating temperature, compared with those in the untreated sample, representing the lowest microbial toxicity. Benzo(a)pyrene produced a significant influence on the ecological toxicity of the hydrochar among the 16 types of PAHs. The impact of thermal treatment on the composition, content, and toxicity of PAHs was significantly influenced by the adsorption, migration, and desorption of PAHs within hydrochar pores, as well as the disintegration and aggregation of large molecular polymers. The combination of hydrochar with carbonized waste heat and exhaust gas collection could be a promising method to efficiently and affordably reduce hydrochar ecological toxicity.

Agronomic Biofortification of Fodder Maize (Zea mays L.) with Zn for Improving Herbage Productivity and Its Quality

Zinc (Zn) deficiency in soils not only reduces the productivity of forage crops, but also results in inadequate dietary zinc intake for livestock. The objective of this study was to evaluate the impact of different rates and methods of applying ZnSO4 to both soil and foliage on the yield and quality of fodder maize grown in a sandy loam soil testing low in DTPA-extractable Zn. A 2-year field experiment was conducted with six treatments including control, foliar application of 0.3% ZnSO4 at 30 days after sowing (DAS) (F1), foliar application of 0.3% ZnSO4 at 30 and 40 DAS (F2), soil application of 16 kg ha−1 ZnSO4 (S16) and a combination of both soil and foliar ZnSO4 application (S16 + F1 and S16 + F2). Increase in green herbage yield by 25%, dry matter yield by 47% and Zn content by 79% was observed under S16 + F2 treatment over the control. Zinc application improved N, K, Cu and crude protein content of herbage significantly over the control. Thus, the study shows that significant improvement in growth parameters, herbage yield and quality of maize can be achieved with soil Zn application + two foliar sprays of ZnSO4 at 30 and 40 DAS, thereby ensuring availability of improved fodder Zn to the livestock.