Plant Root Zone Research Articles

MICROMYCETES IN ROOT ZONE OF SOYBEAN PLANTS AND THEIR FUNCTIONAL EFFECT ON PLANTS

Objective. Characterize the fungal coenosis of the root zone of soybean plants and investigate the functional effect of isolated micromycetes on plants. Methods. The mycocenosis of different spheres of the root zone of soybean plants was studied under the conditions of field experiments on sod-medium-podzolic dusty-sandy soil. Soil sampling, isolation, accounting and cultivation of fungi were carried out according to generally accepted methods. Measuring the number of micromycetes in the spacing and the rhizosphere of soybean was carried out by the Waksman’s soil dilutions method. To extract mycobiota of rhizoplane, the method of washing from the surface of soybean roots, followed by dilution and deep sowing in the digest medium was used. Endophytes were isolated from the tissues of healthy unaffected soybean roots after their surface sterilization with alcohol (96%) for 1.5 min. Cultural and morphological characteristics of fungi were studied on wort agar, Chapek's agar medium, and potato-glucose agar. Their identification was carried out according to the determinants appropriate for a specific systematic group of micromycetes. The functional effect of micromycetes on plants was evaluated using bioassays on corn seedlings. Results. The mycocenosis of sod-podzolic soil was formed by micromycetes belonging to the genera Acremonium Link, Alternaria Nees, Cladosporium Corda, Fusarium Link:Fr, Gliocladium Corda, Mortierella Coem, Mucor Mich, Penicillium Link:Fr, Rhizopus Ehrenb, Trichoderma Hers, among which micromycetes of the genus Penicillium (28.05 ± 3.13 thous CFU per 1 g of dry soil) were the most common. Under the influence of root exudates, the total number of soya bean rhizospheric soil fungi increased threefold and amounted to 212.30 ± 16.73 thous CFU per 1 g of dry soil; in the rhizosphere fungi of the genus Fusarium prevailed (152.63 ± 13.27 thous CFU per 1 g of dry soil). Mycocenosis of the rhizoplane of soybean plants was qualitatively and quantitatively depleted, as compared to the rhizosphere, and consisted mainly of representatives of the genera Fusarium (10.18 ± 3.93 thous CFU per 1 g of dry roots) and Gliocladium (6.88 ± 1.20 thous CFU per 1 g of dry roots). The endophytic mycobiota of soybean was formed by micromycetes of the genera Penicillium (44 %), Chaetomium (21 %), Fusarium (21 %), Verticillium (7 %), Phoma (7 %). Micromycetes isolated from the root zone of soybean plants differed in their functional effect on plants. The largest share of the studied fungi (61 %) are producers of growth-stimulating substances of various origin, 18 % of strains are characterized by a phytotoxic effect on plants, 21 % do not have a pronounced effect on plants. Conclusion. The fungal coenosis of the root zone of soybean was characterized, the functional effect of isolated micromycetes on plants was investigated.

The influence of micronized sulfur amendments on the chemical properties of the calcareous soil and wheat growth

High soil pH constrains the availability of many plant nutrients including phosphorus (P). Sulfur (S) application to soil is a commonly used method to reduce the soil pH in the plant root zone, increase the availability of nutrients and thus obtain a higher yield. However, the particle size of the S is the most important factor in decreasing the soil pH. This study aimed to investigate the effect of different doses of micronized S application (0, 125, 250, and 375 kg ha−1) on the chemical properties of calcareous soil and the yield and nutrient contents of two wheat cultivars (Burgos and Zhivago). The results indicated that soil pH and CaCO3 content of soil decreased with increasing doses of S application. Soil organic carbon content slightly increased with all S applications in Burgos wheat variety. The highest increase was recorded in the 375 kg ha−1 S application, but no significant difference was determined in the Zhivago variety. The available Cu content in soil varied between 3.43 and 3.55 mg kg−1, Fe content was between 13.86 and 14.93 mg kg−1, Mn content was between 22.73 and 25.65 mg kg−1, and Zn content was between 0.53 and 0.62 mg kg−1. The results revealed that soil pH and CaCO3 content decreased with liquid micronized S applications, however, the effect of S applications on exchangeable cations and heavy metal content was not significant.

Агрегатування сільськогосподарської техніки — одна з сучасних актуальних проблем землеробської механіки

Goal. To determine the formation of symbioticand photosynthetic apparatus, soil microbiota, andseed productivity of soybean varieties of differentprecociousness after seed inoculation with noduleand endophytic bacteria under irrigation conditionsof the Southern Steppe of Ukraine. Methods. Field(determination of the number of nodules on plantroots, total leaf surface, photosynthesis efficiency,soy seed productivity), laboratory (number of soilmicroorganisms), statistical. Results. On average,over 3 years of research (2018–2020), the leafsurface area after endophytic rhizobial inoculationof seeds with RyzobinK + Bacillus sp. 4 was greaterby 63.8–52.6% compared to non-inoculatedplants. In the root zone of plants, the developmentof pedo-trophic, proto-trophic, oligo-nitrogen-trophic,and nitrogen-fixing microorganisms was activatedduring complex endophyte-rhizobial inoculation.Complex inoculation of soy seeds stimulated theformation of a symbiotic system, the number ofnodules increased by 60–65%, and their weight —by 12–51%. In an average of 3 years, during thepre-sowing treatment of seeds with RyzobinK ++ Bacillus sp. 4, the highest yield of soy seeds ofDiona was 2.66 t/ha, and Aratta variety — was2.90 t/ha. Conclusions. The use of nodule andendophytic soy bacteria for complex inoculationof seeds of the ultra-early variety Diona and themid-early variety Aratta contributes to the active developmentof plants with an increased leaf surfaceand high photo assimilation productivity, stimulatesthe growth of agronomically useful soil microorganisms.The highest yield of soybean seeds wasformed by the pre-sowing treatment of seeds withRyzobinK + Bacillus sp.4 and was 28.5–31.8% higherthan in the control variants.

Response of leaf nutrients, yield, growth parameters, and evapotranspiration of sweet corn (Zea mays L. saccharata Sturt) to shallow and saline groundwater depths

ABSTRACT This study was carried out to assess the effects of main and interactive groundwater salinities (GWS) (GWS1:0.38, GWS2: 5.0, and GWS3: 10 dS m−1) and groundwater depths (GWD) (GWD1: 0.30, GWD2: 0.55, and GWD3: 0.80 m) on yield and growth parameters of sweet corn. The canned seed yield in the GWS2 and GWS3 treatments reduced by 21.97% and 54.87%, respectively, as compared to the GWS1. Increasing GWS from 0.38 to 5.0 and 10.0 dS m−1 decreased aboveground fresh biomass by 16.67 and 37.95%, respectively. The groundwater contribution to ET varied from 26.80% to 87.10%, and capillary rise from groundwater to plant root zone decreased significantly with increasing GWD. The results showed that plant growth was not significantly affected under 0.38 dS m−1 GWS conditions at 0.55 m GWD, while the groundwater contribution to ET was about 52%. Stomata and SPAD values increased by 36.36% and 4.34%, respectively, in GWD3 treatment compared to GWD1 treatment. Besides, GWS decreased the leaf’s K+, K+/Na+, and Ca2+/Na+ ratios at different depths. In conclusion, it can be suggested that GWD should be at least 0.80 m to achieve high sweet corn production in regions with moderately or highly saline groundwater.

Active solar collector located on roof ridge assisted Chinese solar greenhouse for thermal environment enhancement

ABSTRACT Maximizing the use of solar energy to increase the indoor temperature of greenhouse is of great significance to the green and energy-saving intensive greenhouse production in China. In this study, an active solar heating system (ASHS) was developed and analyzed, consisting of five solar water heaters equipped with vacuum tube solar collectors, one heat storage tank and heating system including booster pump and heating pipes. During the day, the water was heated in the solar collectors and stored in tanks before being placed into circulation in the heating pipes to distribute the heat to the aerial and root zones of plants. To evaluate the performance of ASHS and the feasibility of practical application, climate and plant growth parameters were monitored in two Chinese Solar Greenhouses (CSGs) located in Yangling, China. Results revealed that under the operating condition with the flow rate of 5.4 L/min, the effective heat collection, average heat collection efficiency and energy-saving efficiency of ASHS were 1.9 MJ/(m2•h), 64% and 84%, respectively. The coefficient of performance (COP) was between 4.5 and 6.2, and the payback period was 12.0 years. Furthermore, the results revealed that the ASHS successfully provided 76% of its annual heating needs, heated the CSG for 4 months and maintained the nocturnal temperature above 8 ℃. The actual application effect proved that it increased average indoor air temperature by 2.2 ℃ and substrate temperature by 3.3 ℃ in heated greenhouse. The growth rate of tomato plant height in the heated greenhouse was 0.7427 cm/d, greater than that in the unheated greenhouse (0.6 cm/d). The novel system proposed in this study adopting particular location enables the rise of the ambient and the substrate temperatures with lower energy consumption, improvement of the environmental conditions in CSG, and a more suitable growing environment for plants in the cold season.

Plant-derived saponin enhances biodegradation of petroleum hydrocarbons in the rhizosphere of native wild plants

Plant-derived saponins are bioactive surfactant compounds that can solubilize organic pollutants in environmental matrices, thereby facilitating pollutant remediation. Externally applied saponin has potential to enhance total petroleum hydrocarbon (TPH) biodegradation in the root zone (rhizosphere) of wild plants, but the associated mechanisms are not well understood. For the first time, this study evaluated a triterpenoid saponin (from red ash leaves, Alphitonia excelsa) in comparison to a synthetic surfactant (Triton X-100) for their effects on plant growth and biodegradation of TPH in the rhizosphere of two native wild species (a grass, Chloris truncata, and a shrub, Hakea prostrata). The addition of Triton X-100 at the highest level (1000 mg/kg) in the polluted soil significantly hindered the plant growth (reduced plant biomass and photosynthesis) and associated rhizosphere microbial activity in both the studied plants. Therefore, TPH removal in the rhizosphere of both plant species treated with the synthetic surfactant was not enhanced (at the lower level, 500 mg/kg soil) and even slightly decreased (at the highest level) compared to that in the surfactant-free (control) treatment. By contrast, TPH removal was significantly increased with saponin application (up to 60% in C. truncata at 1000 mg/kg due to enhanced plant growth and associated rhizosphere microbial activity). No significant difference was observed between the two saponin application levels. Dehydrogenase activity positively correlated with TPH removal (p < 0.001) and thus this parameter could be used as an indicator to predict the rhizoremediation efficiency. This work indicates that saponin-amended rhizoremediation could be an environmentally friendly and effective biological approach to remediate TPH-polluted soils. It was clear that the enhanced plant growth and rhizosphere microbial activity played a crucial role in TPH rhizoremediation efficiency. The saponin-induced molecular processes that promoted plant growth and soil microbial activity in the rhizosphere warrant further studies.

Machine learning approach to estimate soil matric potential in the plant root zone based on remote sensing data.

There is an increasing interest in using the Internet of Things (IoT) in the agriculture sector to acquire soil- and crop-related parameters that provide helpful information to manage farms more efficiently. One example of this technology is using IoT soil moisture sensors for scheduling irrigation. Soil moisture sensors are usually deployed in nodes. A more significant number of sensors/nodes is recommended in larger fields, such as those found in broadacre agriculture, to better account for soil heterogeneity. However, this comes at a higher and often limiting cost for farmers (purchase, labour costs from installation and removal, and maintenance). Methodologies that enable maintaining the monitoring capability/intensity with a reduced number of in-field sensors would be valuable for the sector and of great interest. In this study, sensor data analysis conducted across two irrigation seasons in three cotton fields from two cotton-growing areas of Australia, identified a relationship between soil matric potential and cumulative satellite-derived crop evapotranspiration (ETcn) between irrigation events. A second-degree function represents this relationship, which is affected by the crop development stage, rainfall, irrigation events and the transition between saturated and non-saturated soil. Two machine learning models [a Dense Multilayer Perceptron (DMP) and Support Vector Regression (SVR) algorithms] were studied to explore these second-degree function properties and assess whether the models were capable of learning the pattern of the soil matric potential-ETcn relation to estimate soil moisture from satellite-derived ETc measurements. The algorithms performance evaluation in predicting soil matric potential applied the k-fold method in each farm individually and combining data from all fields and seasons. The latter approach made it possible to avoid the influence of farm consultants’ decisions regarding when to irrigate the crop in the training process. Both algorithms accurately estimated soil matric potential for individual (up to 90% of predicted values within ±10 kPa) and combined datasets (73% of predicted values within ±10 kPa). The technique presented here can accurately monitor soil matric potential in the root zone of cotton plants with reduced in-field sensor equipment and offers promising applications for its use in irrigation-decision systems.

Impact Assessment of Different Level of Mycorrhiza on the Growth Parameters and Nutrient Content of Capsicum annum

Soil microbes play an important role in the biogeochemical cycling of nutrients and their availability to plants, which is important for sustaining soil health and agricultural sustainability. In light of this, vesicular arbuscular mycorrhiza (VAM) plays an important function. Hyphae of VAM can reach far beyond the plant root zone, allowing it to obtain nutrients from a considerably larger region of soil. Mycorrhiza improves plant nutrition by facilitating the uptake of minerals such as phosphorus and immobile trace elements such as zinc, cobalt, magnesium, iron, copper, molybdenum, and others. Mycorrhiza improves plant growth, productivity and yield by increasing the rate of photosynthesis. In the present study Glomus fasciculatum was tested on Capsicum annum plant with different inoculum levels (100, 150, 200 and 400 chlamydospores/kg soil) and found that Plant height, Root length, Dry weight of root and shoot, NPK content, per cent mycorrhizal colonization and sporocarp number were maximum when 400 spores were used for inoculation and minimum were found in untreated plants. SPAD chlorophyll content was highest at 90 DAT among all the observation periods.

Domates (Solanum lycopersicium L.) Bitkisinde, Verticillium Solgunluğu (Verticillium Dahliae Kleb.) ve Erken Yanıklığı [Alternaria solani (Ell. Ve G. Martin) Sor.] Hastalıklarına Karşı Clonostachys rosea (Sch.) Schroers ve Samuels’nin Etkisinin Belirlenmesi

The effectiveness of Clonostachys rosea against Verticillium wilt (Verticillium dahliae) and early blight (Alternaria solani) diseases, as the two most important problems in tomato cultivation with significant economic losses, was determined. It was determined that C. rosea was effective on A. solani and V. dahliae and suppressed mycelial growth. Also, the C. rosea on wheat grains inoculated to plants at 20 g, 30 g, and 40 g concentrations before and after pathogens inoculation. Then, fungal discs (2 mm in diameter) from V. dahliae growing colonies were inoculated on the host plant root zone. A. solani was also inoculated (1x106 conidia ml-1) by spraying the foliar parts of the plants. Results showed that V. dahliae caused 76.0% disease severity in control plants, while the disease severity indices were 58.3%, 55.3%, and 25.3% at 20 g, 30 g, and 40 g C. rosea application, respectively. In A. solani x C. rosea treatments, the disease severities were determined as 96.6%, 63.3%, 43.6% and 46.6% in control, 20 g, 30 g, and 40 g application of C. rosea, respectively. The pathogen suppression rates by C. rosea at 30g application dose was 54.8% against A. solani and at 40 g application dose was 66.6% against V. dahliae. The effects of C. rosea on plant growth parameters were also determined. Results showed that C. rosea had a positive effect on the morphological parameters in tomato plants.

The Characteristics of Time-Dependent Changes of Coefficient of Permeability for Superabsorbent Polymer-Soil Mixtures.

Water uptake dynamics of superabsorbent polymers (SAP) in soil is of key importance for the optimum application of these materials in environmental engineering and agriculture, so goal of this paper is to determine time dependent values of coefficient of permeability for various SAP-soil mixtures. Retaining water in soil is a key requirement in critical zones to support plant growth. There is an urgent need for technologies that can increase soil water retention, given the increasing prevalence of droughts and scarcity of clean water as the climate changes, combined with the rising demand for food by a growing world population. SAPs are materials that can absorb significant amounts of water, and thus have tremendous potential to help increase water retention in soil. However, while some studies have characterized the equilibrium swelling behavior of SAPs in soil, how their addition influences the time-dependent flow of water through soil remains poorly understood. Here, we address this gap in knowledge by directly measuring the coefficient of permeability of SAP-soil mixtures, testing different soil grain sizes, SAP grain sizes, and different SAP-soil ratios. We find that SAP addition can dramatically hinder the flow rate of water through soil—reducing the permeability by several orders of magnitude, and in some cases causing complete blockage of water infiltration, at mass fractions as small as 1%. In this scenario coefficient of permeability of 1.23 × 10−4 m/s dropped by a factor of ~10 after 14 min, a factor of ~100 after 36 min, and by nearly a factor of ~1000 after 63 min, eventually causing complete blockage of infiltration after 67 min. Authors concluded that in this particular situation the size and quantity of SAP particles was enough to nearly completely fill the available pore space resulting in rendering the soil column almost completely impermeable. Moreover, we demonstrate that these effects are well-described by a simple hydraulic model of the mutual interactions between SAP and soil grains, providing more generally-applicable and quantitative principles to model SAP-soil permeability in applications. Ultimately, this work could help evaluate the optimal proportions and grain sizes of SAPs to use for a given soil to simultaneously achieve a desirable permeability along with increased water holding capacity in the plant root zone.

Developing a 3D Hydrodynamic and Water Quality Model for Floating Treatment Wetlands to Study the Flow Structure and Nutrient Removal Performance of Different Configurations

Floating treatment wetlands (FTWs) are widely used in surface water. The nutrient removal performance depends on both physical processes and chemical/biological transformations in FTWs. However, research describing the coupling processes of hydrodynamic and water quality in the system remains limited. Therefore, a coupled three-dimensional model of hydrodynamic and water quality for FTWs was developed based on the Environmental Fluid Dynamics Code (EFDC). Additional plant drag terms were added to the momentum equations to simulate the suspended canopy effect, and the chemical/biological processes occurring in FTWs were integrated into the original water quality equations simultaneously. The fully calibrated model was used to compare the hydrodynamic characteristics and nutrient removal performance of seven FTW configurations. The modeling results showed that the main stream would turn to the bottom and side of the plant root zone because of the block in FTWs. The differences in the hydrodynamic characteristics among the seven configurations led to a difference in water quality improvement effects. Segmenting a single FTW into a pair of parallel FTWs could achieve the maximum nitrogen and phosphorus mass removal. The results of the study are useful for designing an optimal FTW configuration in surface water.

A data-driven Kalman filter-PID controller for fibrous capillary irrigation

Subsurface fibrous capillary irrigation has a great potential for high water-saving capability compared to other irrigation methods. However, it suffers from under-performance due to inaccurate estimation and manipulation of water supply depth (∆h) in the water wetting zone of the plant root, in accordance with the changing dynamics of soil, plant growth, and weather. This work presents the design and experimental implementation of Kalman filter-proportional integral derivative (KF-PID) controller for the subsurface fibrous capillary irrigation system. This controller is designed to control the optimal water supply depth (∆h) between the fibrous capillary interface and the surface of the water, through which water is wicked through the fibrous capillary interface to the root zone of the plant. The designed Kalman filter (KF) uses a dynamic model of the system which was obtained using historical real-time data through data-driven system identification. This yields a state-space model to describe the plant's dynamic characteristics. In addition, the KF will reduce the noise sensor output which will improve the accuracy of ∆h estimation. Furthermore, a PID controller was designed to control minimizes the error between the estimated ∆h and reference ∆h to find an optimal value for ∆h. An experimental investigation on the performance comparison of the designed controller on the cultivation of the Mustard leaf plant is also presented in this paper. To access the performance of the designed control system, three performance indices are used to compare the performance of the proposed controller with a fuzzy controller through simulation using integral absolute error (IAE), integral square error (ISE), and integral absolute square error (ITAE). The results show that the proposed controller has lower values of these indices compared to the fuzzy logic controller. Also, the proposed KF-PID controller was able to estimate the optimal ∆h accurately to ensure supply of water to the fibrous capillary material for effective wetting of the plant root zone. This is evident from water saved in treatment A controlled by KF-PID which is 56.3% greater than the treatment B controlled by the adaptive fuzzy logic. The KF-PID controller shows a slightly better performance in terms of controller performance and water productivity index (WPI) which is 16 g/ Liters higher than the adaptive fuzzy logic controller.

The Effect of Biochar on Root Growth in Sustainable Agriculture

Sustainable agriculture can be used to achieve food security by continuously producing agriculture while taking safety, soil health, and environmental and economic considerations into account. Reduced agricultural land for agricultural production could stifle the growth of sustainable agriculture. This study made use of biochar, which is made from organic waste and serves to temporarily hold soil nutrients in the root zone of plants. The focus of this research was to find new ways to expand coastal land use by using biochar made from organic waste as a soil amendment for agriculture, particularly vegetable production. The study employed a two-factor design: the first was the size of the biochar material, which was coarse and fine, and the second was the biochar dosage, which included 10, 15 and 20 tons per hectare. Coconut shell waste was used to make the biochar. According to the results, the application of course-sized biochar at a dose of 15 tons per hectare resulted in lateral root distribution. Vegetable root development tended to be reduced when fine biochar was used. We can conclude that one of the solutions for sustainable agricultural production is to use biochar ameliorant materials made from environmentally friendly organic waste.&#x0D; Keywords: Biochar, Coastal land, Organic matter, Roots Areas, Soil Carbon, and Sustainaibility Agriculture.

Negative effects of poly(butylene adipate-co-terephthalate) microplastics on Arabidopsis and its root-associated microbiome

The degradable plastic poly(butylene adipate-co-terephthalate) (PBAT) is considered a potential replacement for low-density polyethylene (LDPE) as the main component of mulch film. However, it is not clear whether PBAT is harmful to the plant-soil system. Thus, we determined the effects of LDPE microplastics (LDPE-MPs) and PBAT microplastics (PBAT-MPs) on the growth of Arabidopsis. The inhibitory effect of PBAT-MPs was greater than that of LDPE-MPs on the growth of Arabidopsis. Transcriptome analysis showed that PBAT-MPs severely disrupted the photosynthetic system of Arabidopsis and increased the expression levels of genes in drug transport-related pathways. PBAT-MPs increased the relative abundances of Bradyrhizobium, Hydrogenophaga, and Arthrobacter in the bulk soil and rhizosphere soil. The abundances of Variovorax, Flavobacterium, and Microbacterium increased in the plant root zone only under PBAT-MPs. Functional prediction analysis suggested that microorganisms in the soil and plant root zone could degrade xenobiotics. Furthermore, the degradation products from PBAT comprising adipic acid, terephthalic acid, and butanediol were more toxic than PBAT-MPs. Our findings demonstrate that PBAT-MPs may be degraded by microorganisms to produce chemicals that are highly toxic to plants. Thus, biodegradable plastics may pose a great risk to the environment.

FUNGAL PATHOGENIC COMPLEX OF THE ROOT ZONE OF CULTIVATED SOYBEAN PLANTS

FUNGAL PATHOGENIC COMPLEX OF THE ROOT ZONE OF CULTIVATED SOYBEAN PLANTS

ПОДВИЖНЫЕ ФОРМЫ ЭЛЕМЕНТОВ В ТЕХНОЗЕМАХ ХВОСТОХРАНИЛИЩА НЕРЧИНСКОГО ПОЛИМЕТАЛЛИЧЕСКОГО КОМБИНАТА

Contamination of soils adjacent to the tailings storage facility of the Nerchinsk Polymetallic Complex (East Transbaikalia) is caused by the behaviour of Aeolian processes in a dry sharply continental climate. The studied territory is characterized by a high gross content (mg/kg) of zinc up to 5000, arsenic up to 1400, lead up to 600, cadmium up to 36, antimony up to 30. The method of sequential extraction in static mode was used to determine the ion-exchange water- and acid-soluble, reducible, oxidizable, residual forms of elements. The elements of physical-chemical mobility and bioavailability are arranged in the following series according to their decreasing sequence Zn&gt;Mn&gt;Pb&gt;Ni&gt;Cu&gt;As&gt;Fe. The rhizosphere (root zone) of plants is characterized by the content of oxidized forms of copper, zinc, lead and hard-to-reach forms of arsenic, iron, nickel exceeding that in technosols.

Avoiding the point of no return: Maintaining infiltration to remediate saline-sodic Vertosols in high rainfall environments

Saline-sodic soils are often too saline and alkaline for plant survival. These soils are prone to dispersing and eroding after high rainfall events when salinity is reduced before the sodicity. Cost-effective and water efficient methods are needed to leach salts while maintaining sufficient ionic strength of the soil solution. We tested the ability of gypsum, both alone and combined with elemental sulfur and organic matter to remediate the upper 15 cm of a strongly saline-sodic alkaline Vertosol when leached with deionised water in repacked columns. Prior to leaching, all amendment combinations reduced soil alkalinity by 80% and dispersion by 47% by displacing exchangeable sodium (Na). After leaching with 600 mm of deionised water, electrical conductivity of the soil solution (ECss) decreased from an average of 38–4.8 dS m−1 at 8 cm depth. Importantly, structure was maintained in all amended soils, despite this decrease in ECss. In contrast, for the control treatment, there was a concomitant loss of soil structural stability as ECss decreased. This decrease in stability also occurred in the subsoils of all treatments (which were not amended) because the applied calcium (Ca) precipitated before it could be leached to remediate the deeper layers. This study demonstrated that it was critical to first apply amendments as deep in the soil profile as possible to prevent the development of a non-saline sodic soil. Leaching the soil with low ionic strength water removed excess soluble salts from the plant root zone. We estimated that > 300 mm of water (rainfall or irrigation) was required to leach through the root zone to ensure a suitable soil profile for establishing of salt tolerant pioneer species such as Rhodes grass (Chloris gayana Kunth).

Токсичні властивості свинцю, його вплив на харчові ланцюги і методи ремедиації (огляд літератури)

The purpose of the study was to review the most recent findings related to lead toxicity for plants, animals and humans. It is stated that the highest potential belongs to biological techniques and the most up-to-date lead phytoremediation technologies. Results and discussion. Lead is one of the most toxic heavy metals which frequently occurs in the environment. Various quantitative indices are used to assess lead toxicity at trophic levels of a food chain, including the levels of lead absorption by plants. Hyperaccumulating plants can accumulate more than 1000 mg/kg of the metal. Higher lead concentrations are connected with fruit plants. Lead transport in animals is done through the blood circulatory system, whereby bones are the main lead absorbers (~ 90%), where lead replace calcium and reduces the bone mineral density. Lead poisoning in humans most frequently results from peroral intake and absorption through the gastrointestinal tract. The main process of lead transport from the gastrointestinal tract to various body tissues is conducted via erythrocytes, where lead binds to hemoglobin. The half-life of lead in blood and soft tissues has been estimated as 35 and 40 days, respectively. Lead may stay in the bones up to 30 years; its concentration rate in the teeth and bones increases with age. Over 95% of lead deposit in the skeleton represent an insoluble phosphate. The biological half-life of lead in children is significantly larger than in adults. The total lead load on skeleton makes 80-95% in adults and around 73% in children. Lead toxicity primarily targets the human central nervous system, and child exposure to high amounts of lead from the environment, particularly in the case of anemia, entails low intelligence and movement disorders. Mothers can transmit lead to fetus or infants during breast-feeding. There are various processes that seek to reduce the overall lead concentration and accumulation in the food chain. Out of those, the most effective are biological techniques of lead remediation from contaminated resources. They include phytoremediation and microbiological treatment. The first option reduces lead mobility in the root zone of plants through complex formation. The second option reduces lead availability in the environment via employing local microorganisms. Both options are a natural, safe, efficient, and environmentally friendly technology which implies cost-effective operation and represents no threat to the environment and health. However, a high potential is detected in biotechnological and genetic approaches, such as genomics, metagenomics, metabolomics, proteomics, transcriptomics, nanoparticles, and isotope probing. These are the most up-to-date technologies for lead phytoremediation. The use of omics approaches implies identifying candidate genes for an efficient lead removal, diverse phylogenetic research into the sequence of genes and proteins that control lead bioremediation and genetically modified plants cultivation via transgenesis, which are able to restore various wastewaters, contaminated lands, and can be beneficial for practical application in bioremediation. Conclusion. The most recent research and development in the field of nanosciences provide access to even more efficient and stable approaches to remediation that are being successfully applied in cleaning soils, deposits, solid waste, and wastewaters

Evaluation of soil wetting patterns in drip irrigation

Increasing agricultural water use efficiency is of prime importance owing to the decrease in availability of fresh water for agriculture. In these circumstances, drip irrigation is considered so far as the most efficient irrigation systems and can be utilized correctly with the knowledge of dimension of the soil wetted volume which is the main factors in determining the spacing of drippers. Therefore, the present study was conducted at the Instructional Farm, Faculty of Agricultural Engineering, Bidhan Chandra Krishi Viswavidyalaya, Mohanpur, Nadia, West Bengal during 2019–20 to examine the vertical (Z) and horizontal (W) water fronts advance within the soil profile at the dripper in a clay loam soil. Same volume of water (50 litre) was applied at the rate of 2.3 and 4.9 lph at each irrigation. By observing the soil on the tips of the auger, the depth of wetting was determined and noted down for different points on the line of the wetted area. It was found that there is little variation in the theoretical width and depth with the actual width and depth of wetting of the soil in case of 4.9 lph discharge rate. For the given discharge rate, the inaccuracy was less for the wetted depth than the wetted diameter. So, the information obtained from this investigation, about soil wetting pattern of drip irrigation system can be helpful to decide emitter, lateral spacing and system pressure for delivering required amount of water to the plant root zone. Thus, this investigation can be instrumental in design and management of drip system, which is slowly becoming a promising agricultural water management practice to tackle the huge food productivity problem and environmental issues of developing and under-developed countries.

Evaluation of electrical impedance tomography sensor using internal-external electrodes for small-scale cylindrical root zones

To improve the spatial resolution for mapping of small-scale cylindrical plant root zones using electrical impedance tomography, this paper presents a novel sensor structure, where a ring of 16 external electrodes and an inner ring of 8 internal electrodes are included in an electrode layer. To assess the ability of the structure in the electrode plane as well as the effects of measurement noise, conductivity contrast, radial position of internal electrodes, and measurement strategy on its performance, various simulations and experiments were conducted. Results show that the increased noise level or the decreased conductivity contrast will cause the decrease in resolution. Moreover, half the radius of the imaged domain is a good and compromised choice for the radial position of internal electrodes, and the extended adjacent strategy is an available and relatively better choice. Overall, the internal-external electrodes exhibit benefits in improving and uniforming the resolution.