Cm Of Soil Research Articles

Vertical migration behavior simulation and prediction of Pb and Cd in co-contaminated soil around Pb-Zn smelting slag site

Heavy metal migration in soil poses a serious threat to the soil and groundwater. Understanding the migration pattern of heavy metals (HMs) under different factors could provide a more reasonable position for pollution evaluation and targetoriented treatment of soil heavy metal. In this study, the migration behavior of Pb and Cd in co-contaminated soil under different pH and ionic strength (NaCl concentration) was simulated using convective dispersion equation (CDE). We predicted the migration trends of Pb and Cd in soils after 5, 10, and 20 years via PHREEQC. The results showed that the migration time of Cd in the soil column experiment was about 60 days faster than that of Pb, and the migration trend was much steeper. The CDE was proved to describe the migration behavior of Pb and Cd (R2 > 0.75) in soil. The predicted results showed that Cd migrated to 15–20 cm of soil within 7 years and Pb stayed mainly in the top 0–6 cm of soil within 5 years as the duration of irrigation increased. Overall, our study is expected to provide new insight into the migration of heavy metal in soil ecosystems and guidance for reducing risk of heavy metal in the environment.

Depth distribution of plant-parasitic nematodes on bentgrass golf greens in Missouri and Indiana.

Control of plant-parasitic nematodes (PPNs) on golf putting greens with nematicides is dependent on the seasonal occurrence and depth distribution of target PPN populations. This study aimed to determine if plant-parasitic nematode populations on golf course putting greens in Missouri and Indiana peaked at a targetable depth at a specific time in the year, focusing primarily on lance (Hoplolaimus spp.) and root-knot (Meloidogyne spp.) nematodes. To elucidate species diversity in the region, rDNA from a subset of lance and root-knot nematodes was sequenced and analyzed, with additional micromorphology of a lance nematode assessed in scanning electron micrographs (SEM). Soil samples were taken to a depth of 25 cm and stratified into 5 cm increments during April, June, August and October at seven sites across Missouri, three in the Kansas City metro of Kansas in 2021 and in ten sites across Indiana in 2022. Samples were stratified in five-centimeter increments and aggregated for a total of 100 cm3 of soil at each depth for each sampling. Samples were processed using a semi-automatic elutriator followed by the sucrose-flotation method, and populations were counted using a hemocytometer and recorded. For molecular characterization, rDNA was extracted and analyzed from 31 individual lance nematodes from one site in Missouri and eight sites in Indiana, and 13 root-knot nematodes from nine sites across Indiana. A significant interaction occurred between sampling month and depth for lance and ring nematodes Missouri/KS, with both PPN populations peaking at the 0-5 cm depth during October, which is well after most targeted nematicide applications are applied. Ring nematodes in Indiana did not follow this trend and were most abundant in August at a depth of 0-5 cm. No significant interaction between depth and month occurred for lance or root-knot nematodes in Indiana, or root-knot nematodes in Missouri/KS. Hoplolaimus stephanus and H. magnistylus were the lance species identified on golf greens, and Meloidogyne naasi, M. graminicola and M. marylandi were the root-knot species identified. Scanning-electron micrographs confirmed morphological characteristics unique to H. stephanus.

First Report and Molecular Variability of Belonolaimus longicaudatus Associated with Turfgrass in Maryland.

Turfgrass is a crop used extensively in athletic fields and golf courses in Maryland. A soil sample collected in July 2023 from an athletic field in Baltimore County, Maryland, part of a turfgrass nematode survey, contained Belonolaimus longicaudatus. In the southeastern United States, B. longicaudatus is an economically important pathogen of warm season turfgrass. The density was four individuals/100 cm3 of soil, and no visual symptoms were observed in the bermudagrass field. Morphological features and morphometrics of males and females were consistent with B. longicaudatus and placed the Maryland population in a subclade that was geographically represented by populations from north and west Florida, Texas, and South Carolina. Sequencing of the internal transcribed spacer region ITS1 and ITS2 and 28S large ribosomal subunit D2-23 expansion region confirmed the species' identity. Phylogenetic trees and parsimony network analysis placed the Maryland isolate in a large grouping of B. longicaudatus populations including those from Alabama, Delaware, Florida, Indiana, Mississippi, South Carolina, and Texas. To our knowledge, this is the first report of B. longicaudatus in Maryland.

Effect of stand age on soil microbial metabolic limitation and enzyme activities in Robinia pseudoacacia L. plantations in the loess hilly‐gully region, China

AbstractSoil heterotrophic microorganisms play crucial roles in soil biogeochemical cycles by secreting extracellular enzymes, but their metabolism is often limited by resource availability. Identifying major resources that limit soil microbial metabolism could help to create reasonable management practices for the maintenance of ecosystem function. Robinia pseudoacacia plantations perform crucial functions in reconstituting the ecological integrity of disturbed ecosystems; however, soil microbial metabolic limitations in R. pseudoacacia plantations remain poorly understood. Herein, R. pseudoacacia plantations of four age classes (10, 22, 37, and 47 years old) were sampled in the loess hilly‐gully region of northern Shaanxi Province in China. This study analyzed the effects of stand age on soil extracellular enzyme activities and soil microbial metabolic limitation. It also determined the main factor driving soil microbial metabolic limitation and extracellular enzyme activities. The results of ecoenzymatic stoichiometry showed that nitrogen (N) limited soil microbial metabolism in R. pseudoacacia plantations. Soil microbial metabolism at 10 and 22 years old were more carbon (C)‐ and N‐limited than that at 37 and 47 years old. Except for N‐ and phosphorus (P)‐acquiring enzyme activities at 10–20 cm, soil C‐, N‐, and P‐acquiring enzyme activities (in 0–10 and 10–20 cm of soil) at 10 and 22 years old were significantly higher than those at 37 and 47 years old. The enzymatic ratio of C:N:phosphorus(P) acquisition in all R. pseudoacacia plantations, regardless of stand age and soil depth, deviated from 1:1:1. Soil nutrients explained most of the variation (90.80%) in soil extracellular enzyme activities based on variation‐partitioning analysis. The partial least squares path model showed that soil nutrients had the highest total negative effect on microbial C limitation and microbial N/P limitation. Our results confirmed that microbial metabolic limitation was induced by soil resource deficits. The findings provide another visual that increases our understanding of soil microbial metabolic limitation in R. pseudoacacia plantations.

Karık ve Damla Sulama Yöntemleriyle Kırmızı Biberde Farklı Sulama Stratejilerinin Yaprak Osmotik Potansiyeli ile K ve Ca İyon Konsantrasyonları Üzerine Etkilerinin Belirlenmesi

A study was managed to identify the water stress effect on marketable yield, osmatic potential, and potassium (K) and calcium (Ca) ions for drip and furrow irrigated processing red pepper in the 2010 and 2011 growing seasons in Tarsus, Turkey. The treatments for drip irrigation; comprise full irrigation (DFI1.0), deficit irrigation DDI0.75, DPRD0.5, DFPRD0.5, and DDI0.5; for furrow irrigation; full irrigation (FFI1.0), fix alternative furrow (FAF0.5) and PRD furrow (FPRD0.5). FAF0.5 and FPRD0.5 received 50 % of the water applied to FFI1.0. In FAF0.5 the same furrows were irrigated while in FPRD0.5 irrigated alternately. Irrigation methods and irrigation levels had a remarkable effect on the total yield of red pepper in both experimental years. Drip irrigation treatments manufactured higher red pepper yields than the furrow irrigation treatments. The maximum yield in the drip irrigation system was acquired from the DFI1.0 treatment followed by DDI0.75, DDI0.5, and DFPRD0.5 treatments. Though DPRD0.5, DFPRD0.5, and DDI0.5 applied the same amount of water, DPRD0.5 resulted in a higher yield. In furrow treatments, FFI1.0 resulted in the highest yield followed by FPRD0.5 and FAF0.5. Water use efficiency (WUE) diminished with increasing the water amount for drip and furrow irrigation methods. While lower osmotic potential values were measured in full irrigation treatments in furrow and drip irrigation plots, higher osmotic potential values were determined in treatments where water stress was determined in both years. In both drip and furrow irrigation, the lowest Ca (%) values were obtained in full irrigation, while the highest Ca values were obtained in limited irrigation with water stress in the 2010 and 2011 years. K ion values were generally similar in the first and fourth pepper harvests in drip and furrow irrigation.

Desiccation of undamaged grasses in the topsoil causes Namibia’s fairy circles – Response to Jürgens & Gröngröft (2023)

In a novel study, Getzin et al. (2022) have excavated 500 grasses at four regions of the Namib to systematically investigate the temporal process of how the young grasses die in fairy circles. Based on measurements of the root lengths, statistical testing, and comparative photo documentations the authors showed that sand termite herbivory did not cause the death of the freshly germinated grasses within fairy circles (FCs). Roots of those dead grasses were initially undamaged and even longer than those of the living grasses outside in the vegetation matrix, which is contrary to termite herbivory. The dying annual grasses within FCs had significantly higher root-to-shoot ratios than the vital grasses in the matrix, both of which can be attributed to the same grass-triggering rain event. This indicates that they died from water stress because the desiccating grasses invested biomass resources into roots, trying to reach the deeper soil layers with more moisture, but they failed.Jürgens and Gröngröft (2023) commented on our research findings. Here, we shed light on their statements by investigating the existing data evidence on the Namib fairy circles, which includes a thorough literature review about the proposed termite-feeding mechanism, as well as describing the properties of soil water within and around the FCs. Our review shows that there is no single study to date that has demonstrated with systematic field evidence in the form of root measurements and data from several regions of the Namib that the green germinating grasses within the FCs would be killed by root herbivory of sand termites.We emphasize that the top 10 cm of soil in the FCs is very susceptible to drying out. In this topsoil layer, the freshly germinated grasses with their 10 cm long roots die quickly after rainfall due to lack of water, because these small plants cannot reach and utilize the higher soil moisture content, which is only found in deeper soil layers below the dry topsoil. Based on 400 measurements of soil moisture during the rainy season 2024, we show that the topsoil in the FCs is significantly drier than in the matrix outside. Finally, we show that the soil physical conditions allow a very high hydraulic conductivity that supports the “uptake-diffusion feedback” during the first weeks after grass-triggering rainfall. During the first two weeks, the soil moisture at 20 cm depth ranged for several rainfall events between 9% and 18% within the FCs, hence way above the 6–8% threshold below which the hydraulic conductivity strongly declines. Even 20 days after rainfall, soil moisture was still above 8%. During this biologically active period, new grasses germinate after about five days, the large perennial grasses along the FC edge resprout and strongly draw water with their established root system at 20–30 cm depth, and the freshly germinated grasses in the FCs desiccate and die within 10–20 days. With our continuous soil moisture measurements, we argue that the quickly greening and competitively superior grasses on the FC edge, as well as the vital matrix grasses, draw soil water from the FCs. This rapid depletion of soil water and drying out of the topsoil leads to the death of the new grasses in the fairy circles.

Early potassium fertilization in cover plant previous to soybean crop in highly weathered soil

Soybean crops are of great economic importance in Brazil due to its cultivation in different regions of the country, like in Mato Grosso with approximately 19,235.60 thousand hectares cultivated annually and a production of 86,484.30 thousand tons in the 21/22 harvest. Direct sowing has been widely used in production, the plants that precede the crop are fertilized, with increased benefits of the use of straw through nutrient cycling, and the succession crop would benefit from the potassium, being a way that guarantees greater fertilization efficiency, with potassium being released gradually into the soil. The objective was to evaluate the effect of potassium doses applied to U. ruziziensis on forage straw production and potassium availability in the soil profile cultivated with soybeans in succession. The experimental design was in randomized blocks, with five (5) treatments and four (4) replications, totaling twenty (20) plots. The size of each plot was 2 m wide by 3 m long (6 m²). The treatments consisted of (T0) control, (T1) 25 kg ha-1 of K2O, (T2) 50 kg ha-1 of K2O, (T3) 75 kg ha-1 of K2O, (T4) 100 kg ha-1 of K2O. Straw productivity was evaluated, potassium content was determined, and potassium accumulation by forage straw was calculated. The potassium doses provided a linear increase in straw production, potassium content and accumulation in U. ruziziensis., with the highest potassium content in the soil being obtained in the first 20 cm of soil.

Eryngium foetidum Reported as a New Host of Meloidogyne enterolobii in the State of Pará, in the Eastern Amazon Region, Brazil

Amazon chicory (Eryngium foetidum L. [Apiaceae]), also known as culantro, is native to Tropical America and the West Indies. It belongs to the unconventional food plants (UFPs) group, and in addition to be consumed as a spice herb, it possesses a wide range of ethnomedicinal uses (Paul et al. 2011). In 2019, in the eastern Amazon region of Brazil, state of Pará, producers of E. foetidum in the municipality of Castanhal (01°15'363” S 047°10'232” W) reported the occurrence of underdeveloped plants with leaf yellowing and a large number of galls in the root system, which are typical symptoms of root-knotting nematode. Soil and root samples were collected and sent to the Nematology Laboratory (LabNema) located at the Faculty of Agrarian and Veterinary Sciences, UNESP, Jaboticabal, São Paulo, Brazil. A total of 46 second-stage juveniles (J2s) were extracted per 100 cm3 of soil, and a total of 460 eggs and J2s Meloidogyne spp. were found per gram of root. Morphological and molecular techniques were used to identify the species. The analysis of the perineal patter of ten females revealed thin striations in an oval shape with a high and semi-trapezoidal dorsal arch. No striations were observed in the perivulvar region. The labial region of the ten males analyzed exhibited a non-prominent labial disc, fused and slightly recessed submedian lips, with no apparent annulations. The morphological characteristics observed in the adults were consistent with those originally described for Meloidogyne enterolobii (Yang; Eisenback, 1983), confirming the species purity of the recovered population. Three individual nematodes had their 18S rDNA region sequenced (Holterman et al. 2006) which showed an average identity of 99.7% with other sequences of M. enterolobii available in the GenBank database. A Bayesian phylogenetic tree was constructed, providing insights into the specific relationship of M. enterolobii recovered from E. foetidum with other related nematodes. Each of the three sequenced nematodes represented a unique haplotype, resulting in their separation into distinct clades. Moreover, the obtained sequences presented polymorphisms that differed from the M. enterolobii sequences already available in the database, highlighting the genetic diversity of this species in relation to its original host (Silva et al. 2021). The species M. enterolobii was also confirmed using species-specific primers for M. incognita, M. javanica, and M. enterolobii (Zijlstra et al. 2000; Tigano et al. 2010). To confirm the pathogenicity of M. enterolobii on E. foetidum, a modified Koch Postulate was conducted. Six seedlings of E. foetidum were transplanted individually to 10-liter pots containing autoclaved soil. Each pot was then inoculated with 5 mL of a suspension containing 3,000 eggs and J2s from the original population of M. enterolobii obtained from E. foetidum. After 90 days, the inoculated plants exhibited root galls with a plentiful egg mass, in contrast to the healthy non-inoculated plants. The average number of M. enterolobii nematodes recovered from the roots of the inoculated plants was 42,040 eggs and J2s, resulting in a reproduction factor (RF) of 14.0. The importance of reporting the occurrence of M. enterolobii in E. foetidum is due to the fact that this plant species is cultivated in a crop rotation system with other vegetables such as lettuce and coriander, which are also hosts of M. enterolobii. Consequently, different crop rotation strategies and control alternatives need to be considered in areas where E. foetidum is grown. This is the first report of E. foetidum serving as a host for the root-knot nematode M. enterolobii worldwide.

Effects of depth of straw returning on maize yield potential and greenhouse gas emissions.

Appropriate straw incorporation has ample agronomic and environmental benefits, but most studies are limited to straw mulching or application on the soil surface. To determine the effect of depth of straw incorporation on the crop yield, soil organic carbon (SOC), total nitrogen (TN) and greenhouse gas emission, a total of 4 treatments were set up in this study, which comprised no straw returning (CK), straw returning at 15cm (S15), straw returning at 25cm (S25) and straw returning at 40cm (S40). The results showed that straw incorporation significantly increased SOC, TN and C:N ratio. Compared with CK treatments, substantial increases in the grain yield (by 4.17~5.49% for S15 and 6.64~10.06% for S25) were observed under S15 and S25 treatments. S15 and S25 could significantly improve the carbon and nitrogen status of the 0-40cm soil layer, thereby increased maize yield. The results showed that the maize yield was closely related to the soil carbon and nitrogen index of the 0-40cm soil layer. In order to further evaluate the environmental benefits of straw returning, this study measured the global warming potential (GWP) and greenhouse gas emission intensity (GHGI). Compared with CK treatments, the GWP of S15, S25 and S40 treatments was increased by 9.35~20.37%, 4.27~7.67% and 0.72~6.14%, respectively, among which the S15 treatment contributed the most to the GWP of farmland. GHGI is an evaluation index of low-carbon agriculture at this stage, which takes into account both crop yield and global warming potential. In this study, GHGI showed a different trend from GWP. Compared with CK treatments, the S25 treatments had no significant difference in 2020, and decreased significantly in 2021 and 2022. This is due to the combined effect of maize yield and cumulative greenhouse gas emissions, indicating that the appropriate straw returning method can not only reduce the intensity of greenhouse gas emissions but also improve soil productivity and enhance the carbon sequestration effect of farmland soil, which is an ideal soil improvement and fertilization measure.

Burial and subsequent growth of rigid ryegrass (Lolium rigidum) and ripgut brome (Bromus diandrus) following strategic deep tillage

AbstractSoil amelioration via strategic deep tillage is occasionally utilized within conservation tillage systems to alleviate soil constraints, but its impact on weed seed burial and subsequent growth within the agronomic system is poorly understood. This study assessed the effects of different strategic deep-tillage practices, including soil loosening (deep ripping), soil mixing (rotary spading), or soil inversion (moldboard plow), on weed seed burial and subsequent weed growth, compared with a no-till control. The tillage practices were applied in 2019 at Yerecoin and Darkan, WA, and data on weed seed burial and growth were collected during the following 3-yr winter crop rotation (2019 to 2021). Soil inversion buried 89% of rigid ryegrass (Lolium rigidum Gaudin) and ripgut brome (Bromus diandrus Roth) seeds to a depth of 10 to 20 cm at both sites, while soil loosening and mixing left between 31% and 91% of the seeds in the top 0 to 10 cm of soil, with broad variation between sites. Few seeds were buried beyond 20 cm despite tillage working depths exceeding 30 cm at both sites. Soil inversion reduced the density of L. rigidum to <1 plant m−2 for 3 yr after strategic tillage. Bromus diandrus density was initially reduced to 0 to 1 plant m−2 by soil inversion, but increased to 4 plants m−2 at Yerecoin in 2020 and 147 plants at Darkan in 2021. Soil loosening or mixing did not consistently decrease weed density. The field data were used to parameterize a model that predicted weed density following strategic tillage with greater accuracy for soil inversion than for loosening or mixing. The findings provide important insights into the effects of strategic deep tillage on weed management in conservational agricultural systems and demonstrate the potential of models for optimizing weed management strategies.

Light and Electron Microscopy Study of Opportunistic Free-Living Nematodes Scavenging and Thriving within Buried Dinosaur Bones

Abstract Nematode worms are the most abundant multicellular organism on Earth. They thrive in every habitat known, and they are voracious feeders within the top 70 cm of soils. Their sturdy cuticle protects them from environmental factors and predators. Nematodes play a significant role in the decomposition of vertebrate remains in soil and serve as indicators of nutrients that enter soils during decomposition. Certain parasitic nematodes have been identified in fossil remains, but reports of fossil worms are rare. We demonstrate the abundant presence of opportunistic nematodes feeding within dinosaur bones from the Hell Creek formation, MT. The presence of visible worm ultrastructure indicates that they were alive when preserved within the dinosaur bones. Our findings are identical to worms characterized as “blood parasites” in a dinosaur bone from Brazil, demonstrating that there is sufficient soft tissue within dinosaur bone canals to sustain large populations of nematodes post-mortem.

Optimized Fertilizer–Water Management Improves Carrot Quality and Soil Nutrition and Reduces Greenhouse Gas Emissions on the North China Plain

In order to improve carrot quality and soil nutrition and reduce the environmental pollution caused by intensive carrot production, more comprehensive combined water–fertilizer management strategies are necessary. This study hypothesizes that optimal management of water and fertilizer can improve carrot yield and quality and reduce greenhouse gas emissions and soil nutrient residues. Thus, coordinated water–fertilizer management strategies were tested for carrot production on the North China Plain over two consecutive growing seasons. Four treatments were tested: local standard fertilization and irrigation practices (FNP); optimized irrigation and chemical nitrogen, phosphorus, and potassium fertilizer (OPT); OPT treatment with partial replacement of chemical fertilizer with peanut shell (PS); and OPT treatment with partial replacement of chemical fertilizer with mushroom residue (M). Compared to the FNP treatment, there were statistically significant increases in soluble sugars (12–27%) and free amino acids (14–26%), and decreases in the nitrate content (7–17%) of fleshy root in the OPT, PS, and M treatments. In autumn carrots, the OPT and M treatments decreased yield, whereas PS increased yield; spring carrot yield was significantly decreased in the OPT, PS, and M groups compared to the FNP group. There were no significant effects of the treatment group on carrot growth rates, nutrient accumulation, or nutrient distribution. However, the OPT, PS, and M treatments were associated with significantly increased partial productivity of phosphate fertilizer (233–363%), reduced residual levels of nitrate and available phosphorus in the top 80 cm of soil, and decreased greenhouse gas emissions by 8–18% compared to the FNP treatment. These results highlight the effectiveness of partial organic fertilizer substitution and integrated water–fertilizer management to produce high-quality carrots with minimal environmental damage.

Vertical tillage effects on crop production and pest management in Pennsylvania

AbstractWithin the last four decades, widespread transition to no‐till corn (Zea mays L.) and soybean [Glycine max (L.) Merr.] production in Pennsylvania has improved soil conservation and soil quality but can result in residue and pest management challenges. To effectively manage residue in no‐till cropping systems, some growers have adopted vertical tillage, a residue management practice characterized by cutting and incorporating crop residue within the top 5–10 cm of soil. Despite few studies documenting effects on crop production and soil conservation, vertical tillage has become widespread. Replicated on‐farm trials were conducted over a 2‐year period in 2021–2022 to improve grower and consultant decision‐making regarding the role of vertical tillage relative to continuous no‐till on southeast Pennsylvania farms located within the environmentally sensitive Chesapeake Bay Watershed. We assessed the effects of vertical tillage on corn residue cover, winter annual weed abundance, slug damage, and soybean performance in 40 paired strip trials comparing spring vertical tillage to no‐till using three different vertical tillage tools used by farmer cooperators. Vertical tillage equipment type is a driver of variation in changes to surface residue cover. Baseline surface residue cover was similar among no‐till strips, but a greater proportion (32%) of strips had mean surface residue cover levels below a 60% conservation program compliance threshold when a Kuhn‐Krause Excelerator was used. Relative to no‐till, vertical tillage resulted in a 50% reduction in winter annual weed cover, a 24% reduction in slug damage, and no significant differences in soybean stand establishment or grain yield.

Efficiency of phosphate fertilizers containing growth promoters in plant fertilization

Optimizing water and nutrient absorption in plants can be achieved through a practical strategy: the combination of plant growth promoters (PGPs) with phosphate fertilizers. This synergistic approach holds promise for enhancing agricultural productivity and sustainability. The objectives of this work were to produce new phosphate fertilizers containing PGPs and to evaluate the efficiency in promoting the growth of the roots and shoots and increased phosphorus (P) uptake of plants. The fertilizers produced contained reactive natural phosphate rock from Morocco and PGPs indole-3-butyric acid, humic substances or Trichoderma afroharzianum, and a control fertilizer, without adding PGPs. The agronomic efficiency of this fertilizers were evaluated in two contrasting soils. The additional treatment with the monoammonium phosphate was included. The experimental unit consisted of rhyzobox containing 350 cm3 of soil, where a soybean plant was grown. Thirty days after sowing, the root length, average root diameter, root tips, and fine roots were measured using WinRHIZO software. The dry matter and P content of the roots and shoots were determined. PGPs have a great potential to increase the efficiency of P absorption by plants and the photosynthetic rate, and have a great potential to increase phosphorus use efficiency. The effects of PGPs were observed in the architecture of the root system, leaf area, and increased P content by plants. In sandy soil, the application of phosphate rock containing humic substances, Trichoderma afroharzianum, and indole-3-butyric increases the total phosphorus uptake by 26.5%, 16.3%, and 12.2%, respectively.

Prevalence, Spatial Distribution, and Population Density of Plant-Parasitic Nematodes in Vegetable Fields of North Carolina, South Carolina, and Tennessee Counties

Plant-parasitic nematodes are a diverse group of soilborne plant pathogens that limit the yield of numerous vegetable crops globally. Few studies have investigated nematode populations affecting vegetable crops in Tennessee and North and South Carolina. Between December 2020 and October 2022, vegetable fields in selected counties of these states were sampled for plant-parasitic nematodes. Data on the prevalence, spatial distribution, and population density of seven genera of plant-parasitic nematodes, identified via morphology, were collected. Root-knot nematodes were identified in 60% of the fields sampled, with population densities ranging from 10 to 10,400 nematodes per 500 cm3 of soil. Detection rates of other genera as percentages of total fields sampled were: spiral (42%), stubby root (32%), stunt (21%), ring (13%), and lesion (8%) nematodes. Out of eight crops sampled, fields either currently or formerly planted to tomato or pepper were the most frequently sampled in the survey (77% of total fields). This is the first survey to collect data on populations of plant-parasitic nematodes in this region, and the results highlight the need for continued surveillance and study of their impact in vegetable production.

On the study of the wheat nematode Anguina tritici chitwood, 1935 and their importance in wheat cultivation in Uzbekistan conditions

In our study, the wheat nematode Anguina tritici Chitwood, 1935 was registered in wheat ears in surveyed grain-growing farms in 5 regions of Uzbekistan. Larval stages of two- and three-year-old nematodes were observed at different stages of development in plant organs and root soil. The population density, depending on the living conditions, ranged from 8 to 60 larvae per 100 cm3 of soil and roots, and in stems and leaves from 12 to 25 larvae per 20 g. In heavily infected ears of wheat, the number of galls ranged from 9 to 50 copies. For the effectiveness of agrotechnical measures, such as crop rotation in the fight against wheat nematode, experiments were conducted to assess the viability of wheat nematode larvae. One-year-old, two-year-old and three-year-old galls were selected and the number of larvae was counted. It turned out that the number of viable larvae in annual galls is higher than in two-year and three-year-old galls.This is due to the fact that after a period of time, the accumulated food reserves in the body were used up for the viability of the larvae.

Enhancement on migration and biodegradation of Diaphorobacter sp. LW2 mediated by Pythium ultimum in soil with different particle sizes.

The composition and structure of natural soil are very complex, leading to the difficult contact between hydrophobic organic compounds and degrading-bacteria in contaminated soil, making pollutants hard to be removed from the soil. Several researches have reported the bacterial migration in unsaturated soil mediated by fungal hyphae, but bacterial movement in soil of different particle sizes or in heterogeneous soil was unclear. The remediation of contaminated soil enhanced by hyphae still needs further research. In this case, the migration and biodegradation of Diaphorobacter sp. LW2 in soil was investigated in presence of Pythium ultimum. Hyphae could promote the growth and migration of LW2 in culture medium. It was also confirmed that LW2 was able to migrate in the growth direction and against the growth direction along hyphae. Mediated by hyphae, motile strain LW2 translocated over 3 cm in soil with different particle size (CS1, 1.0-2.0 mm; CS2, 0.5-1.0mm; MS, 0.25-0.5 mm and FS, <0.25 mm), and it need shorter time in bigger particle soils. In inhomogeneous soil, hyphae participated in the distribution of introduced bacteria, and the total number of bacteria increased. Pythium ultimum enhanced the migration and survival of LW2 in soil, improving the bioremediation of polluted soil. The results of this study indicate that the mobilization of degrading bacteria mediated by Pythium ultimum in soil has great potential for application in bioremediation of contaminated soil.

Increasing cotton lint yield and water use efficiency for subsurface drip irrigation without mulching.

Planting without mulching can eliminate the residual film pollution caused by the long-term use of plastic film covers, but it will increase soil moisture evaporation and heat loss and severely reduce water use efficiency and cotton productivity in cotton (Gossypium hirsutum L.) fields in arid regions. It is unclear whether the advantages of subsurface drip irrigation and nighttime irrigation can be leveraged to reduce the amount of irrigation applied in fields, improve the soil and leaf hydrothermal environments, and increase the synchronicity of yield and water use efficiency (WUE). Therefore, in a two-year field experiment (2019-2020), cotton was grown under different irrigation treatments (I5, 3753 m3 ha-1; I4, 3477 m3 ha-1; I3, 3201 m3 ha-1; I2, 2925 m3 ha-1; and I1, 2649 m3 ha-1). The soil volumetric moisture content, soil temperature, leaf relative water content (RWC), daily changes in gas exchange parameters, lint yield, and WUE were evaluated. The results showed that reducing irrigation can reduce the soil volumetric moisture content (0-40cm soil layer), increase the soil temperature and soil temperature conductivity, and increase the leaf temperature, intercellular carbon dioxide concentration (Ci), and WUE; however, reducing irrigation is not conducive to increasing the leaf RWC, net photosynthetic rate (Pn), stomatal conductance (Gs), or transpiration rate (Tr). There was no significant difference in WUE between the I3 and I4 treatments from 8:00 to 20:00, but the lint yield in these treatments increased by 2.8-12.2% compared to that in the I5 treatment, with no significant difference between the I3 and I4 treatments. In addition, a related analysis revealed that the positive effects of the leaf hydrothermal environment on the Pn and soil temperature on the WUE occurs during the same period (10:00-16:00). Overall, an irrigation amount of 3201-3477 m3 ha-1 applied with a subsurface nighttime irrigation system without mulching can enhance the soil moisture content and soil temperature, maintain a high photosynthetic capacity, and increase the lint yield and WUE. These results revealed that the negative impacts of plastic film contamination in arid areas can be alleviated.

Nitrogen mineralization in the oldest climax communities in the eastern Mediterranean region

In this study, we investigated how tree species affect N mineralization in connection to some soil properties and seconder metabolite levels of litter, in the soil of the oldest native forest communities. In the oldest pure communities of Pinus nigra (PN), Fagus orientalis (FO), and Abies bornmuelleriana (AB) in the mountain range of Mount Uludağ, Bursa, Turkey, annual net yield and N mineralization in the 0–5- and 5–20-cm soil layers were determined in a field incubation study over 1 year. Sampling locations were chosen from 1300 to 1600 m a.s.l., and moisture content (%), pH, water-holding capacity (%), organic C, total N, and C/N ratio, and annual net mineral N yield of the soil and hydrolyzed tannic acid and total phenolic compounds in litter were compared for these forest communities. F. orientalis had the highest annual net Nmin yield (43.9 ± 4.8 kg ha–1 a–1), P. nigra the lowest (30.5 ± 4.2 kg ha–1 a–1). Our findings show that in the oldest forest ecosystems, the seasonal soil moisture content and tree species play an essential role in N cycling and that hydrolyzed tannic acids and total phenolic compounds effectively control N turnover. Tannic acid and total phenolics in the litter were found to inhibit nitrification, but total phenolics were found to stimulate ammonification.

The importance of forests in the environment

The importance of forests in the environment