Soil Pretreatment Research Articles

Transfer and transport of microplastics from biosolids to agricultural soils and the wider environment

Between April to November of 2017, microplastics (MPs) were analysed in biosolids from two separate suppliers, and in the soils of three agricultural fields to which they were applied, in Ontario, Canada. Soils of a control site with no history of biosolid application were also examined. High MP concentrations of between 8.7 × 103 MP kg−1 and 1.4 × 104 MP kg−1 were found in biosolids samples. Lower MP concentrations observed in Provider 2 biosolids may be due to storage, settling and supernatant removal prior to applications. Annual MP additions to agricultural soils across Ontario were estimated at between 4.1 × 1011 and 1.3 × 1012 particles. All fields receiving biosolids had higher soil pre-treatment MP concentrations than the control. The field with the greatest number of previous biosolid treatments had the highest pre-treatment soil MP concentrations; suggesting some MP retention in soils between applications. Immediately following biosolids applications, two fields demonstrated significant increases in soil MP concentrations, with preferential retention of MP fibers over fragments observed, while a reduction in soil MP concentrations were observed in the third. Surprisingly, only one field demonstrated a net gain in soil MPs over the course of the study. At all three fields, >99% of MPs applied in biosolids in 2017 were unaccounted for. The study suggests that despite adhering to applicable legislation, biosolids applications at all sites likely result in high rates of MP export. This study is the first to track MP transport through soils following their application in biosolids, and contributes to filling current knowledge gaps regarding export of MPs to aquatic systems from the terrestrial environment.

Enhancement of Drought Tolerance in Cucumber Plants by Natural Carbon Materials.

Stress induced by climate change is a widespread and global phenomenon. Unexpected drought stress has a substantial effect on the growth and productivity of valuable crops. The effects of carbon materials on living organisms in response to abiotic stresses remain poorly understood. In this study, we proposed a new method for enhancing drought tolerance in cucumber (Cucumis sativus L.) using carbon nanotubes and natural carbon materials called shungite, which can be easily mixed into any soil. We analyzed the phenotype and physiological changes in cucumber plants grown under conditions of drought stress. Shungite-treated cucumber plants were healthier, with dark green leaves, than control plants when watering was withheld for 21 days. Furthermore, compared with the control cucumber group, in the shungite-treated plants, the monodehydroascorbate content of the leaf, which is a representative marker of oxidative damage, was 66% lower. In addition, major scavenger units of reactive oxygen species and related drought stress marker genes were significantly upregulated. These results indicate that successive pretreatment of soil with low-cost natural carbon material improved the tolerance of cucumber plants to drought stress.

Determination of Six Heavy Metal Elements Such as Co in Solid Waste by ICP-MS

Soil In this paper, tetraacid system -microwave digestion was established as a soil pretreatment method. The analytical methods for simultaneous determination of six heavy metals in Co, V, Sb, Mn, Mo and Tl by inductively coupled plasma mass spectrometry (ICP-MS) were discussed. The results show that the correlation curves of standard curves for soil and sediment Cr, Ni, Cu, Zn, Cd and Pb were determined by ICP-MS method to be 1.0000, 0.9999, 0.9999, 0.9999, 0.9999, and 0.9999, respectively. The detection limits were 0.1 mg/kg, 0.1mg/kg, 0.1mg/kg, 0.1mg/kg, 0.1mg/kg, and 0.1mg/kg, respectively. The relative standard deviations of precision are 1.2%∼3.7%, 1.4%∼2.9%, 3.7%∼6.6%, 1.1%∼1.3%, 6.1%∼7.6% and 2.7%∼7.1%. The accuracy of the standard substance measured values are within the uncertainty range. The laboratory has verified the method of determining heavy metals in soil waste by ICP-MS. The linear relationship, detection limit, precision and accuracy are in line with the standard HJ 766-2015 requirements.

Degradation of petroleum hydrocarbons in unsaturated soil and effects on subsequent biodegradation by potassium permanganate

To date, the oxidation of petroleum hydrocarbons using permanganate has been investigated rarely. Only a few studies on the remediation of unsaturated soil using permanganate can be found in the literature. This is, to the best of our knowledge, the first study conducted using permanganate pretreatment to degrade petroleum hydrocarbons in unsaturated soil in combination with subsequent bioaugmentation. The pretreatment of diesel-contaminated unsaturated soil with 0.5-pore-volume (5%) potassium permanganate (PP) by solution pouring and foam spraying (with a surfactant) achieved the total petroleum hydrocarbon (TPH) removal efficiencies of 37% and 72.1%, respectively. The PP foam, when coupled with bioaugmentation foam, further degraded the TPH to a final concentration of 438mg/kg (92.1% total reduction). The experiment was conducted without soil mixing or disturbance. The relatively high TPH removal efficiency achieved by the PP-bioaugmentation serial foam application may be attributed to an increase in soil pH caused by the PP and effective infiltration of the remediation agent by foaming. The applied PP foam increased the pH of the acidic soil, thus enhancing microbial activity. The first-order biodegradation rate after PP oxidation was calculated to be 0.068d-1. Furthermore, 94% of the group of relatively persistent hydrocarbons (C18-C22) was removed by PP-bioaugmentation, as verified by chromatogram peaks. Some physicochemical parameters related to contaminant removal efficiency were also evaluated. The results reveal that PP can degrade soil TPH and significantly enhance the biodegradation rate in unsaturated diesel-contaminated soil when combined with bioaugmentation foam.

Cadmium and zinc bioaccumulation by Phytolacca americana from hydroponic media and contaminated soils

Hydroponic, greenhouse and field experiments were conducted to explore the potential of pokeweed (Phytolacca americana L.) to accumulate Zn and Cd from nutrient solutions and contaminated soils. The hydroponic results confirmed that this native species is a strong Zn and Cd bioaccumulator that does not experience severe phytotoxicity until quite high root and shoot concentrations, approaching 4000 and 1600 mg kg−1 of Zn, and 1500 and 500 mg kg−1 of Cd, respectively. These high Zn and Cd concentrations were accompanied by increased sulfur and lower manganese in both shoots and roots. However, in field and greenhouse trials with soils historically contaminated by a number of heavy metals including Zn and Cd, concentrations of Zn and Cd in shoots of P. americana reached concentrations less than 30% and 10%, respectively, of those achieved with hydroponics. The main constraint to phytoremediation of soils by P. americana was the low concentrations of Zn and Cd in soil solution. Pretreatment of the metal-contaminated soil by oxalic acid increased soluble Cd and Zn but failed to increase plant uptake of either metal, a possible result of higher solubility of competing metal ions (Cu, Mn) or low bioavailability of Cd and Zn-oxalate complexes.

The Study of Soil Detoxification of the Municipal Landfill of Solid Waste Using Sorbent "Agroionit"

The technology on separation of the solid wastes at the municipal waste landfills obtaining solid waste and soil, which is sanitized with the use of natural sorbent "Agroionit" is suggested. It showed that sorbent "Agrionite" application in the amount of 16 % in absolutely dry matter could reduce the content of mobile forms of heavy metals up to MPC. To reduce the amount of sorbent up to 12 % pre-treatment of soil with lime in the amount of 0,4 % for the detoxification of zinc, which is slowly absorbed by Agrionite is required. Appropriate changes to the developed technology have been added, including the regulation of temperature and humidity of soil.

Influence of Chemical and Physical Variables on 87Sr/86Sr Isotope Ratios Determination for Geographical Traceability Studies in the Oenological Food Chain

This study summarizes the results obtained from a systematic and long-term project aimed at the development of tools to assess the provenance of food in the oenological sector. 87Sr/86Sr isotope ratios were measured on a representative set of soils, branches, and wines sampled from the Chianti Classico wine production area. In particular, owing to the high spatial resolution of the 87Sr/86Sr ratio in the topsoil, the effect of two mill techniques for soil pretreatment was investigated to verify the influence of the particle dimension on the measured isotopic ratios. Samples with particle sizes ranging from 250 to less than 50 µm were investigated, and the extraction was performed by means of the DIN 19730 procedure. For each sample, the Sr isotope ratio was determined as well. The obtained results showed that the 87Sr/86Sr ratio is not influenced by soil particle size and may represent an effective tool as a geographic provenance indicator for the investigated product.

Use of a Laser Diffractometer to Obtain the Particle Size Distribution of Fine-Grained Soils

Obtaining the particle size distribution (PSD) of fine-grained soils in hydrometer testing has several shortcomings, particularly long test duration, whereas a laser diffractometer can provide a soil’s PSD relatively expediently. PSDs of the finer fraction of several Hawaiian soils using laser diffraction were compared with those from hydrometer testing. The objective was to investigate some key test variables affecting laser diffractometer PSDs including circulation duration, soil pre-treatment with a deflocculant, and the values of test parameters. The following conclusions are drawn. PSD becomes finer with increasing circulation duration. Circulation duration can be excessively large when attempting to match the laser diffractometer and hydrometer PSDs for the untreated soil. Soil should be pre-treated with sodium hexametaphosphate to decrease the circulation or test duration. The larger the real portion of the refractive index (RI), the coarser the soil. RI values must be calibrated for different laser diffractometer models and for different mineralogical compositions as the RI is a function of not only particle size and mineral composition but also the particle shape and light wavelength and different laser diffractometer models utilize different light wavelengths. The smaller the imaginary component of the RI, the more pronounced the finer fraction. The imaginary component also affects the shape of the PSD, especially in the finer spectrum. The optimum real and imaginary values of RI are 1.4 and −0.1i for the laser diffractometer used and for the fines tested in this study, respectively.

Nanoscale zero-valent iron-assisted soil washing for the removal of potentially toxic elements

The present study focuses on soil washing enhancement via soil pretreatment with nanoscale zero-valent iron (nZVI) for the remediation of potentially toxic elements. To this end, soil polluted with As, Cu, Hg, Pb and Sb was partitioned into various grain sizes (500–2000, 125–500 and <125 μm). The fractions were pretreated with nZVI and subsequently subjected, according to grain size, to Wet-High Intensity Magnetic Separation (WHIMS) or hydrocycloning. The results were compared with those obtained in the absence of nanoparticles.An exhaustive characterization of the magnetic signal of the nanoparticles was done. This provided valuable information regarding potentially toxic elements (PTEs) fate, and allowed a metallurgical accounting correction considering the dilution effects caused by nanoparticle addition.As a result, remarkable recovery yields were obtained for Cu, Pb and Sb, which concentrated with the nZVI in the magnetically separated fraction (WHIMS tests) and underflow (hydrocyclone tests). In contrast, Hg, concentrated in the non-magnetic fraction and overflow respectively, while the behavior of As was unaltered by the nZVI pretreatment. All things considered, the addition of nZVI enhanced the efficiency of soil washing, particularly for larger fractions (125–2000 μm). The proposed methodology lays the foundations for nanoparticle utilization in soil washing operations.

Comparisons of soil pretreatment methods for SF-ICP-MS determination of ultra-trace level plutonium in water soluble and exchangeable fractions

In this study, we developed a method to evaluate the potentially bioavailable fraction of Pu in agricultural soils by determining their water soluble and exchangeable fractions. Three commonly used pretreatment methods were compared for their ability and performances to process the extracted solutions. Results showed that these three methods were able to obtain consistent Pu concentration results; however, based on the experimental performance factors, we considered that wet-ashing followed by Fe(OH)3 co-precipitation was the best pretreatment method, with which high 242Pu recoveries for the overall process were realized for the water soluble fraction (69.8%) and the exchangeable fraction (70.6%).

Testing soil solarization as an alternative method for weed suppression at archaeological sites

Archaeological sites around Greece are usually large scale open spaces that are colonized by dense populations of various weed species soon after the excavations. This causes severe problems to both the monument and the functionality of the site that includes mechanical damages to the architectural parts, obstruction of restoration and excavation works, obstruction of visitor access, visual exclusion of the monument, threat of fire during the dry summer period and chemical corrosion. The national law for the protection of man and the environment prohibits the spraying of pesticides in archaeological sites. Soil solarization is a non-chemical method of weed suppression that could be applied as an alternative method in archaeological sites. The aim of the study was to determine the most effective combination of plastic mulch type, application period and soil pretreatment in weed suppression. An experimental field was set up in the Agricultural University of Athens in July 2014. Soil solarization treatments included two types of plastic mulch (opaque and clear), two application periods (July to August and August to September) and two types of soil pretreatments (no tillage, with tillage). Weed species growth was significantly affected by soil solarization treatments. Visual ratings of weed control revealed that clear plastic mulching during July-August provided close to 100% control for six months after treatments, even without soil pretreatment. Clear plastic mulching during August-September provided four months of around 100% residual control, while opaque mulching provided only one to two months of above 90% control for both application periods and soil pretreatments. Lowest fresh and dry biomass weight was measured under clear plastic mulching applied July-August with no differences between soil pretreatments. Second best results concerning biomass weight were obtained by clear plastic mulching applied August-September, with no differences between soil pretreatments. In conclusion, it was shown that soil solarization can be utilized effectively as an alternative tool for weed control in archaeological sites.

Effects of Soil Pre-Treatment with Basamid® Granules, Brassica juncea, Raphanus sativus, and Tagetes patula on Bacterial and Fungal Communities at Two Apple Replant Disease Sites.

Nurseries producing apple and rose rootstock plants, apple orchards as well as rose production often experience replanting problems after several cultivations at the same site when a chemical soil disinfectant is not applied. The etiology of apple and rose replanting problems is most likely caused by soil-borne pathogen complex, defined as “replant disease (RD)”. Symptoms typical of RD are reduced shoot and root growth, a smaller leaf area, a significant decrease in plant biomass, yield and fruit quality and a shorter life span. In our previous study, we showed that RD symptoms were reduced when apple rootstock M106 were grown in RD soils treated either with the soil fumigant Basamid or after biofumigation by incorporating Brassica juncea or Raphanus sativus or by growing Tagetes under field conditions compared to untreated control soil. The present study aimed at identifying potential bacterial and fungal taxa that were affected by different soil treatments and linking bacterial and fungal responders to plant performance. Miseq® Illumina® sequencing of 16S rRNA gene fragments (bacteria) and ITS regions (fungi) amplified from total community DNA extracted from soil samples taken 4 weeks after treatments were performed. Soil properties and culture history of the two RD sites greatly influenced soil microbiomes. Several bacterial genera were identified that significantly increased in treated soils such as Arthrobacter (R. sativus, both sites), Curtobacterium (Basamid, both sites), Terrimonas (Basamid and R. sativus, site A) and Ferruginibacter (B. juncea, site K and R. sativus, site A) that were also significantly and positively correlated with growth of apple M106 plants. Only few fungal genera, such as Podospora, Monographella and Mucor, were significantly promoted in soils treated with B. juncea and R. sativus (both sites). The least pronounced changes were recorded for bacterial as well as fungal communities in the RD soils planted with Tagetes. The detection of bacterial and fungal genera that were significantly increased in relative abundance in response to the treatments and that were positively correlated with plant growth suggests that management of the soil microbial community could contribute to overcome the apple RD encountered at affected sites.

Assessment of potassium speciation in soil using traditional single leaching and modified sequential extraction processes

Purpose The bioavailability of potassium (K) depends on its speciation distribution in the soil. Different methods are commonly used to estimate K speciation including traditional single leaching (TSL) and sequential extraction process (SEP). However, K speciation is largely affected by soil pretreatment methods. The effects of both TSL and SEP soil pretreatment methods were evaluated.

Detection of Soil Nitrogen Using Near Infrared Sensors Based on Soil Pretreatment and Algorithms.

Soil nitrogen content is one of the important growth nutrient parameters of crops. It is a prerequisite for scientific fertilization to accurately grasp soil nutrient information in precision agriculture. The information about nutrients such as nitrogen in the soil can be obtained quickly by using a near-infrared sensor. The data can be analyzed in the detection process, which is nondestructive and non-polluting. In order to investigate the effect of soil pretreatment on nitrogen content by near infrared sensor, 16 nitrogen concentrations were mixed with soil and the soil samples were divided into three groups with different pretreatment. The first group of soil samples with strict pretreatment were dried, ground, sieved and pressed. The second group of soil samples were dried and ground. The third group of soil samples were simply dried. Three linear different modeling methods are used to analyze the spectrum, including partial least squares (PLS), uninformative variable elimination (UVE), competitive adaptive reweighted algorithm (CARS). The model of nonlinear partial least squares which supports vector machine (LS-SVM) is also used to analyze the soil reflectance spectrum. The results show that the soil samples with strict pretreatment have the best accuracy in predicting nitrogen content by near-infrared sensor, and the pretreatment method is suitable for practical application.

Laboratory vs. in situ resin‐core methods to estimate net nitrogen mineralization for comparison of rotation and tillage practices

AbstractProperly estimating soil nitrogen (N) mineralization as a consequence of different agronomic practices would result in better soil N fertility management. In this study, we tested the differences between laboratory and in situ resin‐core incubation methods for estimating soil net N mineralization for long‐term burley tobacco (Nicotiana tobacum L.) tillage and rotation systems. The laboratory incubation method used crushed, homogenized, litter‐free soil samples, and the in situ resin‐core incubation method used an intact soil core with the inclusion of any plant residue below or above ground. Comparisons showed that no‐tillage had significantly increased soil net N mineralization compared to conventional tillage with the laboratory incubation method, while there was no significant difference between tillage methods with the in situ resin‐core method. This indicates that soil pretreatment in the laboratory incubation method can create an “artificial tillage effect” for soil previously managed with no‐tillage, resulting in overestimated soil net N mineralization. The rotation comparison showed that different crop sequences had no impact on measured net N mineralization with the laboratory incubation method. However, a preceding soybean crop did significantly increase net soil N mineralization compared to preceding corn when measured with the in situ resin‐core method. This suggests that discarding plant residue in the laboratory incubation method can neglect the potential effect of plant residue on soil N mineralization. Therefore, it is important to be aware that soil pretreatment may influence soil N mineralization estimates, potentially resulting in flawed decisions for soil N fertility management.

Efficiency of Saccharothrix algeriensis NRRL B-24137 and Its Produced Antifungal Dithiolopyrrolones Compounds to Suppress Fusarium oxysporum-Induced Wilt Disease Occurring in Some Cultivated Crops

Saccharothrix algeriensis NRRL B-24137 (SA) is a well-studied actinobacterium strain for its ability to produce numerous bioactive dithiolopyrrolone derivatives with appreciable antifungal properties. Our study aimed to investigate the possible usefulness of SA and its produced compounds to control several formae speciales of Fusarium oxysporum, which affect different important crops. Such is the case of F. oxysporum f. sp. lini (FOLi), F. oxysporum f. sp. lentis (FOLe), F. oxysporum f. sp. ciceris (FOC) and F. oxysporum f. sp. lycopersici (FOLy) which cause devastating wilt to flax, lentil, chickpea and tomato, respectively. Antagonistic properties of the strain SA have been primarily evaluated in vitro. This screening showed the significant antifusarium activity of the actinobacteria strain against FOLi, FOC, FOLe and FOLy. Consecutively, strain SA and FOLi soil development has been assessed. The SA soil treatment permitted an important decrease (threefold) in the FOLi infestation. Moreover, the actinobacteria soil density seemed maintained after 7-week treatment at an appreciable level of 44×106 CFU/gram of dry soil (gds). Through different pot experiments, soil pre-treatment with the SA strain significantly reduced the disease incidence of FOLi, FOLe, FOC and FOLy by 71.0, 73.3, 61.2 and 59.7%, respectively. However, the treatment with pure dithiolopyrrolones appeared less effective with about 50% of FOLi disease impact reduction, which thus suggested the involvement of more than direct antibiosis in the whole SA biocontrol performance. Globally, significant correlation between the in vitro antagonistic properties of SA and its capacity to reduce the disease occurrence (r=0.81, P≤0.05) has been highlighted.

Induction of SA-signaling pathway and ethylene biosynthesis in Trichoderma harzianum-treated tomato plants after infection of the root-knot nematode Meloidogyne incognita.

Salicylic acid-signaling pathway and ethylene biosynthesis were induced in tomato treated with Trichoderma harzianum when infected by root-knot nematodes and limited the infection by activation of SAR and ethylene production. Soil pre-treatment with Trichoderma harzianum (Th) strains ITEM 908 (T908) and T908-5 decreased susceptibility of tomato to Meloidogyne incognita, as assessed by restriction in nematode reproduction and development. The effect of T. harzianum treatments on plant defense was detected by monitoring the expression of the genes PR-1/PR-5 and JERF3/ACO, markers of the SA- and JA/ET-dependent signaling pathways, respectively. The compatible nematode-plant interaction in absence of fungi caused a marked suppression of PR-1, PR-5, and ACO gene expressions, either locally or systemically, whilst expression of JERF3 gene resulted unaffected. Conversely, when plants were pre-treated with Th-strains, over-expression of PR-1, PR-5, and ACO genes was observed in roots 5days after nematode inoculation. JERF3 gene expression did not change in Th-colonized plants challenged with nematodes. In the absence of nematodes, Trichoderma-root interaction was characterized by the inhibition of both SA-dependent signaling pathway and ET biosynthesis, and, in the case of PR-1 and ACO genes, this inhibition was systemic. JERF3 gene expression was systemically restricted only at the very early stages of plant-fungi interaction. Data presented indicate that Th-colonization primed roots for Systemic Acquired Resistance (SAR) against root-knot nematodes and reacted to nematode infection more efficiently than untreated plants. Such a response probably involves also activation of ET production, through an augmented transcription of the ACO gene, which encodes for the enzyme catalyzing the last step of ET biosynthesis. JA signaling and Induced Systemic Resistance (ISR) do not seem to be involved in the biocontrol action of the tested Th-strains against RKNs.

Enhancement of the Bioremediation of Pyrene-Contaminated Soils Using a Hematite Nanoparticle-based Modified Fenton Oxidation in a Sequenced Approach

ABSTRACTThe effect of modified Fenton oxidation using synthesized hematite nanoparticles and sodium pyrophosphate as a chelating agent was investigated for the pretreatment of pyrene-contaminated soil in a sequence with bioremediation. Synthesized hematite nanoparticles comprised hematite according to X-ray diffraction (XRD) analysis, with particle sizes ranging between 28 and 55 nm. Three pyrene-degrading bacteria, Bacillus cereus, Acidovorax wohlfahrtii, and Bacillus thuringiensis, were isolated from hydrocarbon-contaminated soil and used as inoculums for the bioremediation. A sequence of modified Fenton oxidation-bioremediation using a synthesized hematite nanoparticles dosage of 30 mM and H2O2 concentration of 300 mM significantly enhanced the pyrene removal rate to 96%, 87%, and 82% compared to 88%, 59%, and 37%, which were obtained during the bioremediation alone for synthetically fresh, aged, and naturally contaminated soil with initial pH 7, respectively. The results of kinetic studies indicated that modified Fenton oxidation of pyrene-contaminated soil was best fitted with a pseudo-first order kinetic model. Consequently, a sequence of modified Fenton-bioremediation can effectively remediate polycyclic aromatic hydrocarbon-contaminated sites in a shorter reaction time than bioremediation alone.

ВЛИЯНИЕ ЭЛЕКТРОАКТИВИРОВАННОЙ ВОДЫ ПРИ ПОЛИВЕ НА СОСТАВ И ПРОДУКТИВНОСТЬ ЛИСТОВОГО САЛАТА

The purpose of the study is improving the efficiency of lettuce cultivation by applying electroactivated water (catholyte) for irrigation. Application electroactive water is an ronmentally friendly method of stimulating the growth and development of plants. During laboratory experimental studies on the cultivation of lettuce the influence of different variants of irrigation on the yield of green mass, biochemical-indicators and coefficient of water consumption. In the first embodiment, control is used watering the settled tap water. The second option – watering scheme «water – catholyte», i.e. alternation-mended irrigation water and catholyte, according to the scheme 1:1. The third option – watering scheme «water – catholyte– catholyte» 1:2. The fourth option is only watering with catholyte. The application rate of water to the catholyte is the same. The anolyte in this experiment was used for pre-treatment of soil before sowing. The result is a one-year research found that among the various options elektroaktivisten irrigation water (catholyte) to greater extent influence on productivity. Lettuce have options watering only in the catholyte and alternating watering with plain water and the catholyte is 1:2. The increase in mass of the samples relative to the control (irrigation water) is 17.7% and 36.6%, respectively. Irrigation of the catholyte is et impact not only on productivity but also on the biochemical composition of plants. Reduced with-holding of protein, fiber, sugars and moisture, increasing dry matter content. More economical consumption of irrigation water was carried out in the embodiment of watering plants only in the catholyte. In this case, the consumption of irrigation water amounted to 3.5 g per gram of product. Need to continue research in this direction.

Zinc supplementation induces resistance against root-rot in guar [Cyamopsis tetragonoloba (L.) Taub] seedlings

Soil-borne diseases are a major threat to guar cultivation all over the world. Many soil-borne fungi, including Rhizoctonia, infect plants causing damping-off and wilt diseases. Micronutrients play an important role in controlling the disease. This investigation was aimed to determine the effect of different concentrations of zinc (Zn2+) on biochemical parameters of guar, in relation to resistance against root rot. The guar seedlings were grown under 10 and 20 mg Zn2+ kg−1 soil, in earthen pots, containing inoculated soil. The inoculation of soil was done by the pretreatment of soil with Rhizoctonia inoculums. In the experiment, a control with uninoculated soil was also maintained. Lesion size was decreased by 35.1 and 46.8 % over control at Zn2+ 10 and 20 mg kg−1 soil treatments, respectively. Chlorophyll content, non-structural carbohydrate content and IVDMD (In Vitro Dry Matter Digestibility) per cent decreased in inoculated seedlings as compared to uninoculated seedlings. Phenol content and structural carbohydrates (Acid Detergent Fiber, cellulose, lignin and silica) increased in inoculated seedlings and this increase was further enhanced by Zn2+ 20 mg kg−1 soil treatment, to counteract the fungal invasion. Moreover, a significant increase in IVDMD was also observed at 20 mg Zn2+ kg−1 soil treatment. These results suggested that Zn2+ 20 mg kg−1 soil treatment might be used as soil-nutritive agent to provide resistance in plants against fungal diseases. The application of 20 mg Zn2+ kg−1 soil treatment could also prove useful in minimizing the use of fungicides.