Soil Surfactant Research Articles

Bermudagrass fairway responses to various combinations of a soil surfactant and nitrogen

AbstractSurfactants are commonly employed in sand‐based turfgrass systems to address soil water repellency, which often results in the formation of preferential flow channels leading to non‐uniform wetting patterns. While the influence of soil moisture on nutrient dynamics is well documented, the potential of surfactants to improve N uptake remains poorly understood. A 2‐year study was conducted on ‘Celebration’ bermudagrass [Cynodon dactylon (L.)] fairway to better understand the interaction between fertility programs (296 or 586 kg N ha−1 year−1 from ammonium sulfate and 564 kg N ha−1 year−1 primarily from a controlled‐release N fertilizer) and surfactant rate and frequency (3.2 L ha−1 every 14 or 28 days, or at 6.4 L ha−1 every 28 days) on turfgrass performance, leaf N content, and soil moisture. Overall, no significant interaction was observed between surfactant treatment and fertility program. During the dry season (November to May), fertility programs influenced turfgrass performance parameters with higher N rates consistently leading to improvements in visual quality, normalized difference vegetation index, percent green cover, and dark green color index; however, no differences were observed during the rainy season (June to October). Surfactants showed no effect on turfgrass performance but led to minimal increase in leaf N content from 3.72% to 3.85%. All surfactant treatments reduced water drop penetration time at 0 cm. Moreover, surfactant treatments applied every 28 days regardless of the rate exhibited a higher volumetric water content compared to those applied every 14 days. Surfactant applications might not be an economically feasible strategy to improve leaf N content in South Florida well‐watered bermudagrass fairways.

Application of Natural Surfactant from Morus alba, Soapnut, Sapindus rarak for Enhanced Oil Recovery – Critical Review

This literature discusses the importance of green surfactants in the oil and gas industry as one of the injection types in EOR. The use of green surfactants is good for protecting the environment and marine biodiversity from conventional chemical surfactants. The injection of green surfactants uses natural materials from Soapnut, Mulberry, and Sapindus rarak. These three types of plants are abundant in Indonesia and contain saponin as a material in making good surfactants. Saponin is an amphipathic glycoside that can produce foam when shaken vigorously in a solution. The foam produced by saponin can increase the sweep efficiency in oil wells to increase production. The writing method used in this article is based on scientific literature that discusses the characteristics and physical properties of Soapnut, Mulberry, and Sapindus rarak. The IFT calculation for Soapnut between water and oil reduced from 19 dyne/cm to 2.5 dyne/cm as the surfactant concentration increased from 0 to 12 (w/w%). Mulberry from 43.9 to 17.9 dyne/cm and Sapindus rarak from 3.07 mN/m to 0.96. These natural surfactants enhance water flooding efficiency by 19.6% OOIP, reduces shale contact angle from 52.44 to 19.66, emphasizing natural surfactants oil recovery potential with environmental benefits.

Evaluation of Two Soil Surfactants for Soil Water Management of Creeping Bentgrass on a Wettable Clay Loam Rootzone During an Imposed Dry-down Period1

Abstract The use of soil surfactants is an established practice in turfgrass management. However, a reduction in irrigation water inputs has seldom been quantified on a mineral soil. The purpose of this one-season “proof-of-concept” field study was to apply soil surfactants to creeping bentgrass (Agrostis stolonifera ‘L-93’) on a clay loam rootzone and measure the amount and frequency of irrigation water needed to maintain a daily volumetric water content (VWC) above 25% with a maximum threshold of 35% during an imposed dry-down period. OARS HS (15.9 L·ha−1; 5 fl oz·1000 ft−2) or PBS150 (15.9 L·ha−1; 5 fl oz·1000 ft−2) soil surfactants each were applied three times (30 March, 27 April, 26 May 2016; 28-day interval) prior to a 63-day dry-down period (8 June - 9 August 2016). Compared to maintaining untreated plots irrigated to 35% VWC daily or untreated plots irrigated by threshold, plots treated with OARS HS or PBS150 resulted in a mean range of 36.5 to 41.9% reduction in water applied, and a mean range of 41.6 to 69.7% reduction of irrigation events. Use of soil surfactants in this field study resulted in a statistically significant (p < 0.05) savings in both amount and frequency of irrigation water inputs while maintaining acceptable turfgrass quality. Species used in this study: creeping bentgrass (Agrostis stoloniferous L. ‘L-93’). Chemical soil surfactants used in this study: PBS150 (100% polyoxyalkylene polymers; AquaAid Solutions, Rocky Mount, NC); OARS HS (85% octahydroxy polyoxyalkyene polymers, 7.5% amine salt of alkyl substituted maleic acid, and 7.5% inert ingredient; AquaAid Solutions, Rocky Mount, NC).

Surfactant-Mediated Effects on Hydrological and Physical Soil Properties: Data Synthesis.

Soils are under the threat of a multitude of anthropogenic factors affecting the complex interplay of various physical and hydrological soil processes and properties. One such factor is the group of surface-active compounds. Surfactants have a broad range of applications and can reduce solid-liquid interfacial forces and increase wettability and dispersion of particles. Surfactant effects are context-dependent, giving rise to a wide range of reported effects on different soil processes and properties. Here, we evaluate the evidence base of surfactant research on 11 hydrological and physical soil variables. Our goal was to identify knowledge gaps and test the robustness of the proposed surfactant effects. We found that the current knowledge base is insufficient to reach strong data-backed conclusions about the effects of surfactants in soils. We identified a unique case of bias in the data as a result of conflated patterns from laboratory and field studies. We could not support the hypothesis that the surfactant charge determines soil effects for any of the tested soil variables. We believe that further experiments on surfactant-mediated effects on soil properties and processes are urgently required, paying attention, in particular, to improving experimental design and data reporting standards.

Enhanced solubilization of strongly adsorbed organic pollutants using synthetic and natural surfactants in soil flushing: Column experiment simulation

This study investigates the performance of two non-ionic sugar-based surfactants, belonging to the families of synthetic alkylpoliglucosides and biological rhamnolipids, for enhancing the solubilization and mass transfer of strongly adsorbed hydrophobic organic compounds (HOCs) in porous media. Using toluene and perchloroethylene (PCE) as reference pollutants, a continuous configuration test (column experiment) was performed to simulate a soil flushing process under controlled laboratory conditions. The potential applicability of the selected surfactants in remediation processes was evaluated within the context of Surfactant Enhanced Aquifer Remediation (SEAR) technology. Experimental results showed that both surfactants effectively increased the solubilization of contaminants adsorbed on porous media. Compared to H2O flushing, synthetic surfactant increased the solubilization of toluene by 52% and the solubilization of PCE by 81%, while biosurfactant increased solubilization ability by 73% and 92% for toluene and PCE, respectively. Biosurfactant exhibited the greatest solubilization ability, with 92% of adsorbed toluene and 98% of adsorbed PCE solubilized. This research highlights the potential of green surfactants as efficient candidates for remediation processes due to their excellent solubilization ability and environmentally friendly nature.

An ultra-light sustainable sponge for elimination of microplastics and nanoplastics

The currently established tools and materials for elimination of the emerging contaminants from environmental and food matrices, particularly micro- and nano-scale plastics, have been largely limited by complicated preparation/operation, high cost, and poor degradability. Here we show that, crosslinking naturally occurring corn starch and gelatin produces ultralight porous sponge upon freeze-drying that can be readily enzymatically decomposed to glucose; The sponge affords capture of micro- and nano-scale plastics into its pores by simple pressing in an efficiency up to 90% while preserving excellent mechanical strength. Heterogeneous diffusion was found to play a dominant role in the adsorption of microplastics by the starch-gelatin sponge. Investigations into the performance of the sponge in complex matrices including tap water, sea water, soil surfactant, and take-out dish soup, further reveal a considerably high removal efficiency (60%∼70%) for the microplastics in the real samples. It is also suggested tiny plastics in different sizes be removable using the sponge with controlled pore size. With combined merits of sustainability, cost-effectiveness, and simple operation without the need for professional background for this approach, industrial and even household removal of tiny plastic contaminants from environmental and food samples are within reach.

Surfactant-coated Seed Emergence and Establishment Under Deficit Irrigation in Hydrophilic and Hydrophobic Soils

AbstractSoil water repellency inhibits seed germination and emergence, whereas soil surfactants improve the wettability of water-repellent or hydrophobic soils. An improvement in seed germination and emergence can occur when a soil surfactant is applied directly to the seed and/or to the water repellent soil at sowing. Therefore, a coating process was developed to utilize seed as a soil surfactant carrier. Greenhouse experiments were conducted to evaluate establishment of perennial ryegrass (Lolium perenne L.) seed coated with a soil surfactant (SCS = surfactant- coated seed), as compared to uncoated seed (CHK). Both SCS and CHK were sown in two hydrophilic substrates (100% sand [WSAND], 90:10% v/v sand:peat [WSP], and in two severely hydrophobic sands (100% hydrophobic stearic acid-treated sand [HSS], and hydrophobic 90:10% v/v sand:peat [HSP]). Due to the weight of the coating, SCS was sown at half the amount as compared to CHK; however, final turfgrass establishment in all rootzones with SCS was similar or better than CHK. In WSAND, WSP, and HSP, the volumetric water content was consistently higher in rootzones of SCS treatments versus CHK. SCS represents an opportunity to improve stand establishment and rootzone soil-water dynamics in challenging environmental conditions such as limited precipitation.Species used in this study: Perennial ryegrass, Lolium perenne L.

Surfactant-enhanced mobilization of persistent organic pollutants: Potential for soil and sediment remediation and unintended consequences.

This review aims to provide an overview of the sources and reactions of persistent organic pollutants (POPs) and surfactants in soil and sediments, the surfactant-enhanced solubilisation of POPs, and the unintended consequences of surfactant-induced remediation of soil and sediments contaminated with POPs. POPs include chemical compounds that are recalcitrant to natural degradation through photolytic, chemical, and biological processes in the environment. POPs are potentially toxic compounds mainly used in pesticides, solvents, pharmaceuticals, or industrial applications and pose a significant and persistent risk to the ecosystem and human health. Surfactants can serve as detergents, wetting and foaming compounds, emulsifiers, or dispersants, and have been used extensively to promote the solubilization of POPs and their subsequent removal from environmental matrices, including solid wastes, soil, and sediments. However, improper use of surfactants for remediation of POPs may lead to unintended consequences that include toxicity of surfactants to soil microorganisms and plants, and leaching of POPs, thereby resulting in groundwater contamination.

Insecticidal Activity of a Petroleum-Derived Spray Oil and an Organosilicone Surfactant on Listronotus maculicollis (Kirby) Adults in Laboratory and Greenhouse Bioassays.

The annual bluegrass weevil (ABW), Listronotus maculicollis (Kirby), is a severe pest of golf course turf in eastern North America. The development of pyrethroid- and multiple-resistant populations has created a dire need for novel tactics to control adults. We examined the insecticidal properties of a petroleum-derived spray oil (PDSO; Civitas Turf Defense™.) and an organosilicone, nonionic soil surfactant (Silwet L-77®) in laboratory and greenhouse bioassays. Civitas and Silwet killed > 75% of ABW adults in multiple assays. The level of control was positively affected by increased rate, spray application volume, and soil moisture levels. Dissections of weevils treated with Civitas revealed material entering the insect's hemocoel after 15-30 min, though most mortality occurred between the 3 and 24 h observation periods. Reducing rates while increasing carrier volume or soil moisture levels through irrigation applied prior to or after application also provided excellent control of adults in the same observation periods. Silwet provided comparable, yet less consistent levels of control in the laboratory studies but was excluded from further tests after treated plants demonstrated phytotoxicity in greenhouse studies. Neither Silwet nor Civitas efficacy was affected by pyrethroid resistance levels in the ABW populations tested.

Influence of post-application irrigation and soil surfactants on tebuconazole efficacy against spring dead spot

Spring dead spot (SDS) (Ophiosphaerella spp.) causes damage to hybrid bermudagrass (Cynodon dactylon (L.) Pers. x transvaalensis Burtt Davy) grown in areas where winter dormancy occurs. The pathogen infects the stolons, rhizomes, and roots of warm-season grasses. Symptoms appear as circular, necrotic patches at spring greenup that reduce the playability and aesthetics of bermudagrass. Historically, fungicide efficacy against SDS has been inconsistent. There may be opportunities to improve application and post-application practices to mitigate the inconsistency. A study was conducted from 2019 to 2021 to examine the influence of post-application irrigation and soil surfactant on tebuconazole efficacy against SDS. The study was conducted at three locations: Virginia Tech Turfgrass Research Center (TRC), Blacksburg, VA; Independence Golf Club (IGC), Midlothian, VA; Nutters Crossing Golf Club (NCGC), Salisbury, MD. Tebuconazole was applied in the fall either once at 1.5 kg ai ha−1 or twice at 1.5 kg ai ha−1 two to four weeks apart when soil temperatures were between 10.7 and 21.8 °C. Treatments were applied with or without a soil surfactant and with or without 0.6 cm of post-application irrigation. Bermudagrass was assessed the following spring two or three times for patch number and percent SDS. Data were analyzed by assessment date, subjected to analysis of variance, and means were separated using Tukey's Honest Significant Difference test (P = 0.05). There were no treatment differences at IGC or NCGC in 2020 or 2021. At the TRC in both 2020 and 2021, results were inconsistent with tebuconazole generally suppressing SDS compared to the nontreated control. However, differences between tebuconazole-treated plots were variable. Our study suggests that including a soil surfactant with tebuconazole applications and/or irrigating post-application does not consistently increase SDS suppression.

Certain Soil Surfactants Could Become a Source of Soil Water Repellency after Repeated Application.

Repeated application of soil surfactants, or wetting agents, is a common practice for alleviating soil water repellency associated with soil organic coatings. However, wetting agents are organic compounds that may also coat soil particle surfaces and reduce wettability. For this experiment, hydrophobic sands from the field and fresh, wettable sands were collected and treated with either a polyoxyalkylene polymer (PoAP) or alkyl block polymer (ABP) wetting agent, or water only treatments served as a control. Following repeated treatment application and sequential washings, dissolved and particulate organic carbon (OC) were detected in the leachates of both sand systems. The total amount of OC recovered in leachates was 88% or less than the OC introduced by the wetting agents, indicating sorption of wetting agent monomers to soil particle surfaces regardless of soil hydrophobicity status. While ABP treatment did not alter solid phase organic carbon (SOC) in the sands studied, PoAP application increased SOC by 16% and 45% which was visible in scanning electronic microscopy images, for hydrophobic and wettable sands, respectively. PoAP application also increased the hydrophobicity of both sands that were studied. In contrast, ABP treatment increased the wettability of hydrophobic sand. Our results provide strong evidence that certain wetting agents may increase soil hydrophobicity and exacerbate wettability challenges if used repeatedly over time.

Benefits of a soil surfactant on putting greens under dry and wet conditions

AbstractSoil surfactants are applied to alleviate soil water repellency (SWR). The ability of surfactants to improve turfgrass quality under dry conditions is well documented, but less information exists about their role in situations with water surplus. Our objective was to study responses to monthly application of the surfactant Qualibra® (20 L ha–1) under dry and wet conditions on a sand‐based green covered with creeping bentgrass. Dry conditions implied irrigation to field capacity (FC) once a week (FC1) in 2014 (a year with warm and dry weather from May through July) and deficit irrigation to 60% of FC once a week (DEF1) in 2015 (May through July cool and wet). Wet conditions implied excessive irrigation twice a week (EX2) with 50% more water than needed to replenish FC. The surfactant decreased the average soil water content of the surface 7.5 cm of the root zone from 0.193 to 0.168 m3 m–3 in 2014 and from 0.191 to 0.171 m3 m–3 in 2015. In 2015, the reduction in SWC was stronger with EX2 than with DEF1 irrigation, and this was accompanied by less organic matter accumulation on plots receiving EX2 irrigation. The surfactant reduced the water drop penetration time (WDPT) regardless of irrigation treatments, but improved turfgrass quality only with DEF1 irrigation in 2015. A harder playing surface due to Qualibra® was not observed in 2014 and only at one out of six observations with EX2 irrigation in 2015. We conclude that surfactants imply various benefits depending on water supply.

Soil surfactants applied with 15N labeled urea increases bermudagrass uptake of nitrogen and reduces nitrogen leaching#

AbstractBackground: Increasing nitrogen (N) plant uptake efficiency may result in better plant quality and growth, less N susceptible to leaching and potential contamination to surrounding environments. Soil surfactants have been documented to increase water infiltration and enhance water uniformity throughout the soil profile. Thus, applying a surfactant may increase N uptake and use efficiency.Methods: To investigate this theory, four treatments were applied to bermudagrass grown in leaching columns filled with one of three soils (sand, sandy loam, and sandy clay loam): (1) 10% alkoxylated polyols and 7% of glucoethers surfactant with 15N labeled urea, (2) 10% oleic acid esters of block copolymer surfactant with 15N labeled urea, (3) water with 15N labeled urea, and (4) water without 15N labeled urea. Ambient 15N was determined by the no surfactant and no urea treatment. Each treatment combination was replicated five times and the greenhouse experiment was repeated. Bermudagrass quality and density, leachate volume, and volumetric water content were determined over a 28d period following application. Determination of 15N recovery in plant, soil, and leachate occurred at experiment termination.Results: Applying either surfactant with urea resulted in significantly higher soil volumetric water content (in sandy loam and sandy clay loam soils) and higher bermudagrass clipping yield (in all soils) than urea. Surfactants applied with urea decreased percent 15N recovery in leachate from sand by 37–46%, increased percent 15N recovery in the sandy loam by 37%, and increased percent utilization of 15N by bermudagrass grown in the sandy clay loam by 61–67% compared to urea applied alone.Conclusion: Applying surfactants with urea can increase bermudagrass N uptake efficiency and reduce potential N leaching.

Soil surfactant use on athletic field infield surfaces

AbstractInfield skins are best managed by deep and slow additions of water, but time between games limits these applications. A two‐year study was conducted on a collegiate club softball infield skin to evaluate if applications of soil surfactants could extend soil moisture levels in infields. Seven soil surfactants treatments (Magnus at 15.9 L ha−1 and Magnus 2x at 31.8 L ha−1, Vivax at 15.9 L ha−1, Cascade at 25.5 L ha−1 and Cascade 2x at 50.9 L ha−1, Vivax Tab at 3.3 L water m−2, and Precision EZ Tab at 3.3 L water m−2), as well as a nontreated control (NTC) were applied. Linear regression analysis for soil moisture readings resulted in the Vivax Tab having greatest water loss (−0.44% h−1) along with the NTC (−0.41% h−1) in 2018, however no differences were present in 2019. Contrast statements compared the NTC to the soil surfactants and only Magnus 2x offered a lower water loss over time than NTC. Magnus 2x provided a harder surface than the NTC immediately after watering, and a lower surface hardness than all other treatments after 4 h. In 2019, only Vivax Tabs and Cascade 2x did not have lower surface hardness values than the NTC immediately after watering, and by 8 h after watering only Vivax had a lower surface hardness than NTC. Treatment affects were not consistent from year to year, but it appears increased rates may be needed to change soil moisture and hardness levels for any duration. Future research should focus on increased rates of soil surfactants for infield skins on different skin materials.

Communication of soil water repellency causes, problems, and solutions of intensively managed amenity turf from 2000 to 2020

Abstract Research and investigations of soil water repellency in turfgrass science is a relatively recent endeavor, with most notable progress beginning in the late 1990s and early 2000s and continuing into the present. The objectives of this review were to determine the extent of publications from 2000 to the present on the topic of soil water repellency in turfgrass science, and to assemble a list of soil surfactant product formulations currently available for the amenity turf industry in the USA and United Kingdom/Republic of Ireland in 2019. From 1 January 2000 through 1 June 2020, cumulative number of referred or peer-reviewed research journal articles was 64, the number of abstracts, reports, and proceedings was 87, and the number of professional and trade journal articles was 86. Published works in all categories represented a linear increase over time, and is indicative of increased research activity into this critical area of study. Soil surfactant products and formulations in the USA totaled 192, with 65 in UK/Ireland. The nonionic soil surfactant chemical category is the largest, representing 74% of products in the USA, and 66% of products in UK/Ireland. With formulation category, block copolymers and formulations that contain block copolymers or structurally modified block copolymers as a formulation component comprise the largest group with 58% of products in the USA, and 49% of products in UK/Ireland. Also by formulation category, 25% of USA products and 23% of UK/Ireland products are comprised of anionic and anionic blends and other formulations. Of note, 17% of products in the USA and 28% of products in UK/Ireland do not disclose their formulation. Dr. Louis Dekker’s pioneering insight and advances in soil water repellency has provided turfgrass scientists with a firm foundation and guidance with which to pursue research into the causes, problems, and amelioration of soil water repellency in turfgrass ecosystems. The global amenity turf industry remains the segment where Dr. Dekker’s research has had the most influence and impact to both scientists and turf practitioners.

Influence of Quartz, Kaolin, and Organic Matter on the Critical Micelle Concentration of Tween Surfactants and their Application in Diesel‐Contaminated Soil Washing

AbstractSurfactant solutions are commonly used for the remediation of petroleum‐contaminated soil due to their good petroleum removal performance, time‐saving capability, and cost effectiveness. However, applying surfactants in excess concentrations could make oil recovery difficult. Moreover, residual surfactants in soil are toxic to microorganisms and plants. Thus, it is crucial to identify a suitable surfactant concentration for soil washing applications. The main objective of this study was to evaluate the effect of soil minerals (quartz and kaolin) and organic matter (OM) on the critical micelle concentration (CMC) of polyethoxylated sorbitan ester surfactants (Tween 20, 40, 60, and 80) and its effect on diesel removal from diesel‐contaminated soil by soil washing. The results showed that Tween surfactants with shorter carbon chain lengths required higher CMC for diesel removal from quartz, while those with longer chains needed higher CMC for kaolin cleanup. FTIR results illustrated that oxygenated functional groups of Tween surfactants played an important role in their adsorption on quartz, while alkyl chains of Tween surfactants were responsible for their adsorption on kaolin. At a certain OM concentration, quartz and OM exhibited antagonistic effects, resulting in CMC reduction. In soil washing application, maximum diesel removal could be achieved from kaolin, in the presence of which surfactants exhibited the highest CMC. Based on FTIR results, the adsorbed surfactant could reduce the hydrophobicity of the kaolin surface, thus preventing the re‐deposition of detached diesel.

Frequent soil surfactant applications influence anthracnose on an annual bluegrass research green

AbstractAnthracnose is a turfgrass disease caused by the fungal pathogen Colletotrichum cereale Manns and can cause severe damage to annual bluegrass putting greens. Most turfgrass managers use fungicides to manage anthracnose, although legislation in some locations are compelling managers to seek fungicide alternatives. This 2‐yr field experiment in western Oregon evaluated different rates and application intervals of a soil surfactant—either in combination or in the absence of a spring hollow‐tine aerification on anthracnose severity—on an annual bluegrass (Poa annua L. var. reptans) research green. The highest rate of the soil surfactant applied once or twice a week consistently reduced anthracnose severity in both years compared to the nontreated control, although these applications corresponded to four and eight times the monthly label rate. A quarter of the label rate applied once a week suppressed anthracnose at the peak of disease in the second year and as measured by area under disease progress curves in both years. Spring aerification had no effect on anthracnose severity. Area under volumetric water content progress curves calculated using weekly measurements at a 38‐mm depth were not correlated with area under disease progress curves. The volumetric water content percentage was normally above 25%, reducing the risk of confounding between drought stress and treatments on anthracnose suppression. The highest rate of soil surfactant applied at the most frequent interval was the only treatment to receive acceptable turfgrass quality ratings over both years.

Soil surfactants influence fungicide movement in United States Golf Association putting green soil.

The management of root and crown diseases of turfgrasses is challenging. To manage these diseases, golf course superintendents and other turfgrass managers often spray fungicides at a high carrier volume and irrigate after application to move fungicides into the root zone. Furthermore, previous research has demonstrated that soil surfactants can increase fungicide movement and distribution in soil. Two laboratory experiments were conducted using lysimeters, which were coated with sand on their inner walls to prevent preferential flow and contained 90/10% sand/peat moss (v/v), to determine the effects of soil surfactants on movement of selected fungicides in soil. The soil surface in the first experiment was treated three times at 2-wk intervals with one of three soil surfactants: Aquifer (propoxylated polyethylene glycols), Fleet (polyoxyalkylene polymers), and Revolution (modified alkylated polyol). The soil in the second experiment was treated with only Revolution four times at 2- to 3-wk intervals. Immediately after the final surfactant application, soil columns were treated with 14 C-labeled fungicide. 14 C-Myclobutanil was applied in the first experiment, and 14 C-azoxystrobin and 14 C-propiconazole were applied in the second experiment. In the first experiment, 14 percent units more of the recovered 14 C-myclobutanil was detected in the 5- to 7.6-cm sampling depth, and>4 percent units more was detected in the 7.6- to 10.2-cm depth after soil surfactant application compared with the fungicide-alone treatment. Each soil surfactant also yielded>28% more leachate than the nontreated control. In the second experiment, the total recovered 14 C-azoxystrobin and 14 C-propiconazole in the 7.6- to 10.2-cm depth increased by 2.8 and 1.9 percent units, respectively, compared with soil treated with fungicide alone. These data indicate that soil surfactant inclusion may increase fungicide distribution in soil, which may enhance the efficacy of fungicides in suppressing root and crown diseases.

Drought avoidance of warm‐season turfgrasses affected by irrigation system, soil surfactant revolution, and plant growth regulator trinexapac‐ethyl

AbstractA 2‐yr study was conducted to investigate the effect of subsurface drip irrigation (SDI), the soil surfactant Revolution (modified methyl‐capped block copolymer), and the plant growth regulator PrimoMaxx (a.i. trinexapac‐ethyl [TE]), on rooting, stolons, and rhizomes, percentage green turf coverage, and turf quality of ‘Princess 77’ bermudagrass [Cynodon dactylon (L.) Pers.] and ‘Sea Spray’ seashore paspalum (Paspalum vaginatum Sw.). Grasses were grown on a loamy sand and irrigated with potable or saline ground water at 50% of reference evapotranspiration. Stolon and rhizome weight were not affected by water quality, Revolution, or TE, but SDI plots had greater stolon (1.000 vs. 0.627 g m−2) and rhizome biomass (0.856 vs. 0.493 g m−2) than sprinkler‐irrigated plots. Grasses in drip‐irrigated control plots showed higher root length density (RLD) at 0–10‐cm depth (15.1 vs. 8.3 cm cm−3) and 10–40‐cm depth (7.2 vs. 4.9 cm cm−3) and higher root weight density (RWD) at 0–10‐cm depth (3.5 vs. 2.2 g cm−3) than their sprinkler‐irrigated counterparts. Both RLD and RWD correlated significantly with turfgrass quality (August and September) and green turf cover (July–September). Chemical treatments in combination with irrigation from a sprinkler system resulted in thinner roots and higher RLD at all depths in 2013 when values were compared with the untreated control. Revolution, TE, and SDI all enhanced grasses’ drought avoidance and turf quality, but chemical treatments did not appear to provide additional improvements to grasses in plots irrigated with SDI.

Residues of xenobiotics in the environment and phytotoxic activity in Armenia

The article presents the results of a dynamic study (spring, summer, and fall) of the residues of certain xenobiotics such as organochlorine pesticides (OCPs), synthetic surfactants (SSs) in surface water, soil, sludge, snow and phytotoxic activity in Ararat and Lori marzes of Armenia (2016–2017). A comparative analysis of the environmental status showed that all pollutants studied such as γ-hexachlorocyclohexane (γ-HCH), 1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane (4,4′-DDT), and p-p′-dichlorodiphenyldichloroethylene (4,4′-DDE) were identified in Ararat marz with the average concentrations and detection rates higher than in Lori marz. The prominent contaminant was γ-HCH. The findings indicated the concentrations of OCPs below of regulatory concern. In Ararat marz an increase in the number of sterile pollen grains of certain wild plants was revealed (14.8–26.0%), compared with Lori marz with the levels within the contingent standard of 5–11%. The phytotoxic activity of soil samples from the Ararat marz studied on Avena sativa seedlings was significantly higher in the summer-fall period. These data correlated with monitoring findings showed an increase in the levels of γ-HCH, 4,4′-DDT, SS in the soil and sludge sampled in summer-fall in Ararat marz. This difference in the environmental status can be considered as the result of active agriculture in Ararat marz, whose share of contribution to a relevant branch of the economy of Armenia is two times higher than in Lori marz, 15.4% and 7.9%, respectively. Mentioned rates of agricultural production may be one of the reasons for the environmental deterioration in Ararat marz. The detection of 4,4-DDT, γ-HCH residues testifies the circulation of these formulations in the environment indicating their use in recent past and confirming their persistence. Although since the 70s of the last century the application of OCPs in the Republic of Armenia has been prohibited. The current situation may be explained by low awareness of farmers on different issues related to the safe management of pesticides. To ensure safe working conditions and raise awareness among the farmers we have developed “Recommendations on Safety requirements when working with pesticides” that are approved by the State Service for Food Safety at the Ministry of Agriculture of RA and included in the reference booklets for farmers as guiding information. Our study shows the understanding of associations between the deterioration of the environmental status and share of agriculture contribution to the economy that provides the evidence for future research programs.