Absence Of Soil Research Articles

Advancing noninvasive and nondestructive root phenotyping techniques: A two-phase permittivity model for accurate estimation of root volume

Noninvasive and nondestructive root phenotyping techniques under field conditions are needed to advance plant root science. Soil electrical parameters including capacitance and resistance hold potential to meet this need, although their specific ability to detect roots remains uncertain. In this study, we developed a two-phase root and soil permittivity model at high frequency enabling accurate and noninvasive prediction of root volume. The validation calculation showed that the two-phase model successfully predicts root volume with a minimal error of less than 1 % under the control conditions with roots placed in wet soil and water. Furthermore, we demonstrated that the high-frequency bulk soil capacitance when integrated into an empirical model, can accurately estimate root volume for summer maize (Zea mays L.) in both the field (root mean square error (RMSE) = 1.52 cm3) and in root washing-free measurement applications in the absence of soil (RMSE = 0.36 cm3). When the empirical relationship between high-frequency bulk soil capacitance and root volume is not adequate, the two-phase model can be used to calibrate the empirical model. To this end, a series of soil pot experiments with winter wheat (Triticum aestivum L.) showed that the measurement accuracy can be fundamentally improved. These results highlighted the effectiveness of the two-phase permittivity model, making high-frequency bulk soil capacitance a reliable method for in situ measurement of root volume. It is anticipated that the availability of new equipment for measuring high-frequency soil electrical parameters will lead to widespread adoption of this root phenotyping technique in the future.

Suppression of Phytophthora capsici in Chile Pepper Using Brassica juncea and Hordeum vulgare Cover Crop Residues and Trichoderma harzianum as a Biocontrol Agent.

Phytophthora blight, caused by Phytophthora capsici, is a serious disease of many vegetable crops worldwide. In New Mexico, U.S.A., the disease affects chile pepper (Capsicum annuum L.), a major crop in the state. There is no single tool that effectively controls the disease. Continuous research is needed in identifying combination of tools that can reduce the impact of Phytophthora blight. We explored the potential of combining cover crops and biocontrol agents to reduce soilborne diseases. This study aimed to evaluate the effects of Indian mustard (Brassica juncea L.) cover crop on the antagonistic ability of Trichoderma harzianum against P. capsici in vitro and to quantify the impacts of combining soil amendment with residues from B. juncea and barley (Hordeum vulgare L.) cover crops and plastic covering on infection of chile pepper seedlings by P. capsici under greenhouse conditions. Volatiles from macerated tissue of B. juncea significantly reduced P. capsici and T. harzianum growth in the absence of soil by 89.0 and 79.0%, respectively. When incorporated in soils, volatiles from macerated tissue of B. juncea significantly reduced P. capsici and T. harzianum by 33.4 and 7.8%, respectively. T. harzianum was more resilient to B. juncea biofumigation than P. capsici. Significant reduction in disease incidence was observed with B. juncea-fumigated soil, while no disease suppression was observed with soil incorporation of H. vulgare residues. Covering soil with plastic was necessary for increasing the efficacy of B. juncea biofumigation.

The presence of the plant pathogen Fusarium graminearum as a soil inoculum enhances the rhizosphere survival of bacterial biocontrol strains aimed at the pathogen

AbstractThe serious wheat pathogen Fusarium graminearum causes both root rot and head blight. Some classical biocontrol tests were first used to explore the biocontrol ability of 39 Pseudomonas fluorescens strains. The five most antifungal strains B4, P13, UTPf127, UTPf125 and UTPf105 were selected to screen known antifungal antibiotic genes and greenhouse experiments. The ability of bacteria to colonize wheat rhizosphere and their effect on plant growth in the presence and absence of soil F. graminearum inoculum was studied under greenhouse conditions. Overall, biocontrol bacteria populations were significantly higher in both wheat endo‐and ectorhizosphere of pathogen‐inoculated soil than in healthy soil. The population of all strains differently decreased with time. On day 28, endorhizosphere populations of strain B4 could be detected in inoculated but not healthy soil, while UTPf127 populations remained high in endorhizospheres at all tested times. Isolate B4 and UTPf105 showed the most substantial plant growth in pathogen‐inoculated soil compared to pathogen‐inoculated soil without added bacteria. UTPf127‐treated plants grew better in control soil than when the pathogen was present. In contrast, UTPf125 and P13 showed little effect on plant growth. These results point to complex interactions between pathogen and biocontrol bacteria and suggest that a fungal pathogen in the soil can affect the survival of potential bacterial biological control agents. Additionally, they highlight the importance of screening and evaluating potential biocontrol bacteria against soilborne fungal pathogens by in vivo tests rather than relying on plate screenings.

Aniline degradation and As (III) oxidation and immobilization by thermally activated persulfate

In the Pearl River Delta of China, many sites are likely contaminated with aniline in the soil and arsenic (As) in the groundwater because of a high As background level and the prevailing printing and dyeing industry. This study is to explore the remediation performance of thermally activated persulfate oxidation for the sites with these two contaminants, aniline and As. The As influence on the aniline degradation and vice versa are also systematically investigated. When the molar ratio of aniline to persulfate is 1: 4.65, over 85% of aniline can be degraded at 40 °C in 24 h, and 100 μg L−1 As(III) in solution can be completely adsorbed by the soil. A higher pH favored the aniline degradation but disfavored the As(III) oxidation. Due to the strong buffer capacity of the soil, aniline in the soil could be more quickly degraded than those in the solution. The As(III), however, seem more easily oxidized in the absence of soil. The coexisting Fe2+ can substantially improve As(III) oxidation and immobilization, although the dilute Fe2+ solution may suppress the aniline degradation. The presence of aniline severely inhibited the As(III) oxidation and adsorption, likely due to the competition for the generated free radicals and the adsorption sites on the soils. In contrast, the existing As(III) has a slight effect on aniline degradation. These findings are believed to provide the theoretical basis for the remediation of aniline-arsenic contaminated sites.

Aeroponics: A Polytropic Research Tool in the New Era of Agriculture

Aeroponics is a technique of cultivating or culturing plants in the absence of soil or a consolidated medium. It is that the plant is just grown in the moist air or mist medium to transmit the nutrients required by plants. To be honest I call is as a tool for research and commercial production activities because when we talk about practical application there will be many aspects for consideration such as orientation, site selection, skilled technicians, economic costs weather, and climate mainly the traditional farmers. All these operations cannot be handled by a small and simple farmer with ease, this is the reason for the current trend of aeroponics which is new to people and being practically utilized only for research, aesthetics, and for commercial purposes. Aeroponics need special structures which can maintain a controlled environment for the fulfillment of all the basic and required conditions by the plants being studied or grown inside. It requires proper equipment like aeroponic growth chambers, phytosanitary conditions, cooling mechanization, etc. aeroponics has many uses as they can be grown in less space, are useful for seed production, and used in parks and restaurants for ambiance, can grow crops extraterrestrial, pollution free but can’t be termed as organic as it is grown without the soil but yes, we can say it organically as there is no use of chemical fertilizer or pesticide n herbicides. There is a big debate going on this outside but this is just what my perspective is. Further development should come up for the sustainability of aeroponics as a medium for agricultural practice.

Engagement with Urban Soils Part I: Applying Maya Soil Connectivity Practices to Intergenerational Planning for Urban Sustainability

Urban soil security depends on the means and social practices that enable multiple generations to maintain and improve soil resources. Soils are pivotal to urban sustainability yet seem absent from international planning advisories for sustainable urban development. Subsuming soils under broad and unspecific categories (ecosystem, environment, land, etc.) leaves soil interests indeterminate and largely ignored in urban planning. The absence of soils in sustainable urban planning advice permits planning guidelines that cause increasing land-use conversions which seal soils. Urban patterns of sealed and distanced soils, preventing access to and direct enjoyment of soil benefits, generate disengagement from soils. Despite fierce land-use competition, urban areas offer the greatest potential for soil connectivity exactly because people concentrate there. Based on previous work we accept that everyday opportunities to encounter and directly engage with soils in Pre-Columbian lowland Maya urban life rendered soil connectivity commonplace. Here, we review how the two original routes towards soil connectivity, knowledge exchange and producer–consumer relationships, reinforced and supported regular soil engagement in Maya urban practice. We frame our interpretation of Maya cultural values and urban practices in terms of leading insights from environmental psychology on pro-environmental behaviour and stakeholder attitudes and the principles of building resilience. This allows us to recognise that Maya urban soil connectivity functions thanks to the structural involvement of the largest societal stakeholder group, while imparting soil knowledge is entangled in shared socio-cultural activities rather than a task for a minority of soil specialists. The emerging Maya model for a socially engaged soil-aware urban society combines bottom-up practices and top-down social–ecological cultural values to increase resilience, to diminish reliance on long-distance supply chains, and to maintain productive human–environment relationships over the long term. As such it becomes a primary task for urban planning advice and guidelines to enable and support a widely shared and enduring culture of soil care. Urban sustainable development may only be successful if underpinned by a broadly carried increase in soil knowledge and awareness of intergenerational soil dependency.

Understanding the complexities of Building-Integrated Agriculture. Can food shape the future built environment?

Our food system is facing an unprecedented challenge: feeding a fast growing population without depleting precious resources like energy, soil, and water. Furthermore, the increasing urbanization has rapidly exacerbated the gap between farm to plate, leaving cities vulnerable to changes in the production and supply chain, as demonstrated by recent pandemics and wars. In this context, emerging technologies that allow plants to grow in absence of soil, permit to produce food in high densely built-up areas, bringing food production right were most consumers live. These initiatives enter within the so called Building-Integrated Agriculture (BIA), which is referred as the practice of locating greenhouses and soilless plant cultivation technologies on top and inside mixed-use buildings to exploit the synergies between the building environment and agriculture, involving resource recovery such as water, energy and nutrient flows. This paper aims at determining strategies, objectives, and best practices of BIA projects through the review of 21 case studies, to understand how a new advanced and future-oriented agriculture applied within the cities borders, can possibly shape the urban built environment and food systems of the future.

Effect of Spent Mushroom Compost of Pleurotus eous Strain P-31 on Growth Performance and Nodulation of Cowpea (Vigna unguiculata Walp.).

This study investigated the influence of spent mushroom compost (SMC) of Pleurotus eous strain P-31 on the growth, development and soil rhizobial population associated with nodulation of cowpea (Vigna unguiculata Walp.) black-eye variety, under greenhouse conditions at 28 ± 2ºC for 12 weeks. Sandy loam soil was combined with different percentages of SMC to obtain the following combinations (0%, 5%, 10%, 15%, 20%, 25%, 30%, 100%). Lower concentrations, SMC (5%-25%) promoted plant height, number of leaves, total leaf area, total chlorophyll, chlorophyll a and b as well as dry matter accumulation of shoot and roots after 12 weeks at 28°C-32°C. Soil: SMC concentrations beyond 30% SMC variably depressed the various developmental criteria used in assessing growth. The trend obtained in the assessed parameter were statistically significant (p ≤ 0.05) in decreasing order: 5% SMC < 10% SMC < 15% SMC, < 20% SMC, < 25% SMC, < 30% SMC, < 100% SMC. The cowpea plant efficiently assimilated nitrogen (N2) from the soil: compost. Nodule formation by cowpea was commensurate with increasing percentage of spent compost was highest in 5% SMC (89/plant) and declined with increasing proportion of SMC: soil mixture up to 25% but nodulation of cowpea plant was completely depressed in the absence of soil (100% SMC) pots. The Nodule Index data showed that the best nodule size and weight were formed by cowpea growing in medium containing 5% SMC (18) and 10% SMC (12) and thereafter declined. The nodules were red to pinkish in colour epitomising leghaemoglobin which could initiate nodulation and N2 fixation in soil. This study has shown that 5% SMC-20% SMC could provide favourable conditions in soil as a biofertiliser to improve the growth, development and nodulation of cowpea.

Dispersal of bacteria and stimulation of permafrost decomposition by Collembola

Abstract. Contrary to most soils, permafrost soils have the atypical feature of being almost entirely deprived of soil fauna. Abiotic constraints on the fate of permafrost carbon after thawing are increasingly understood, but biotic constraints remain scarcely investigated. Incubation studies, essential to estimate effects of permafrost thaw on carbon cycling, typically measure the consequences of permafrost thaw in isolation from the topsoil and thus do not account for the effects of altered biotic interactions because of e.g. colonization by soil fauna. Microarthropods facilitate the dispersal of microorganisms in soil, both on their cuticle (ectozoochory) and through their digestive tract (endozoochory), which may be particularly important in permafrost soils, considering that microbial community composition can strongly constrain permafrost biogeochemical processes. Here we tested how a model species of microarthropod (the Collembola Folsomia candida) affected aerobic CO2 production of permafrost soil over a 25 d incubation. By using Collembola stock cultures grown on permafrost soil or on an arctic topsoil, we aimed to assess the potential for endo- and ectozoochory of soil bacteria, while cultures grown on gypsum and sprayed with soil suspensions would allow the observation of only ectozoochory. The presence of Collembola introduced bacterial amplicon sequence variants (ASVs) absent in the no-Collembola control, regardless of their microbiome manipulation, when considering presence–absence metrics (unweighted UniFrac metrics), which resulted in increased species richness. However, these introduced ASVs did not induce changes in bacterial community composition as a whole (accounting for relative abundances, weighted UniFrac), which might only become detectable in the longer term. CO2 production was increased by 25.85 % in the presence of Collembola, about half of which could be attributed to Collembola respiration based on respiration rates measured in the absence of soil. We argue that the rest of the CO2 being respired can be considered a priming effect of the presence of Collembola, i.e. a stimulation of permafrost CO2 production in the presence of active microarthropod decomposers. Overall, our findings underline the importance of biotic interactions in permafrost biogeochemical processes and the need to explore the additive or interactive effects of other soil food web groups of which permafrost soils are deprived.

Increases in the temperature seasonal cycle indicate long-term drying trends in Amazonia

Earth System Models project a wide range of rainfall changes in the Amazon rainforest, and hence changes in soil moisture and evapotranspiration. Hydrological changes are heterogeneous, meaning local measurements are too sparse to constrain projections of large-scale hydrological change. Here we show that changes in the amplitude of the temperature seasonal cycle are strongly correlated with annual mean evaporative fraction (surface latent heat flux as a fraction of surface net radiation) changes, across reanalyses and Earth System Model projections. We find an increase in annual temperature amplitude of 1 °C is associated with a reduction in evaporative fraction of up to 0.04. The observed temperature seasonal cycle amplitude increase (0.4 °C) over the last three decades implies Amazon drying, determined in the absence of soil or energy flux measurements, matches Earth System Model simulations of the recent past. Additionally, Earth System Models predict further temperature seasonal cycle amplitude increases, suggesting drying will continue with future climate change.

Phosphate fertilization and bioactivator influences on fractions of organic matter and soil microbial biomass

Soil organic matter is considered a potential source of phosphorus (P) for plants because of biological cycling. Bioactivators are characterized as tools that can help soil microbial activity and the availability of P demanded by plants. The objective of this study was to evaluate the influence of the use of bioactivators and phosphate fertilization on the activity of soil microbial biomass and humified fractions of organic matter. The experimental design was completely randomized in a factorial scheme (6 × 2), with the first factor consisting of six doses of phosphorus applied to the soil (0, 30, 60, 90, 120, and 150 kg ha-1 of P2O5), using triple superphosphate as the source, and the second factor being the presence or absence of soil and plant bioactivator application, with four replications. The evaluated characteristics were soil microbial biomass carbon (SMBC), soil basal respiration (SBR), microbial biomass nitrogen (MBN), metabolic quotient (qCO2), microbial quotient (qmic), total organic carbon (TOC), fulvic acid fraction carbon (FAC), humic acid fraction carbon (HAC), and humin fraction carbon (HUMC). The use of soil and plant bioactivators and mineral phosphate fertilizer promoted changes in soil microbial activity. Increasing doses of phosphate fertilization promoted a reduction in the carbon characteristics of microbial biomass and basal soil respiration in the presence or absence of soil and plant bioactivators. Moreover, the use of bioactivator promoted higher averages for soil microbial biomass carbon, soil basal respiration, metabolic quotient, humic acid and humin and reduced the levels of microbial quotient, total organic carbon and fulvic acid.

On the torsional buckling moment of cylindrical shells consisting of functionally graded materials resting on the Pasternak-type soil

In this study, the buckling analysis of cylindrical shells made of functionally graded materials (FGMs) under the torsional moment resting on the Pasternak-type soil is performed. After establishing the linear constitutive relations of FGM cylindrical shells within the framework of the modified Donnell type shell theory, the governing equations of FGM cylindrical shells under the torsional moment are derived considering the influence of Pasternak-type soil. Analytical formula for the torsional moment is obtained by choosing the approximation functions that satisfies the boundary conditions in an integral sense. From the obtained formula, the formulas for the critical torsional moment in the presence of Winkler soil and absence of soils are obtained as a special case. Variations of critical torsional moment for different soil coefficients, volume fraction ratio and shell characteristics are investigated in detail. Keywords: functionally graded materials; cylindrical shell; buckling; critical torsional moment; Pasternak-type soil.

Degradation of the Nitrification Inhibitor 3,4-Dimethylpyrazole Phosphate in Soils: Indication of Chemical Pathways

Nitrogen fertilizers amended with nitrification inhibitors (NIs) are used to increase nitrogen use efficiencies in agricultural systems. 3,4-Dimethylpyrazole phosphate (DMPP) is the most successful commercial NI to date but has a highly variable efficacy. To explore whether degradation could contribute to its inconsistent performance, incubation studies were performed with DMPP and 3,4-dimethylpyrazole glycolate (DMPG) in two alkaline clay soils that were treated with the fertilizer ammonium sulfate ((NH4)2SO4). Analysis of the soil extracts revealed a qualitative correlation between the amount of NI present in the soil and inhibition efficiency as well as several degradation products resulting from the oxidation of a methyl side chain and dimerization. A similar outcome was obtained for the degradation in sterilized soil and in accelerated weathering studies in the absence of soil. Our data suggest that chemical and not microbiological pathways are primarily responsible for the degradation of this inhibitor, which could potentially be initiated by reactive oxygen species (ROS) resulting from both biotic and abiotic processes in soils.

INNOVATIVE TECHNOLOGIES IN AGRICULTURE AND ECONOMIC CHALLENGES (ON THE EXAMPLE OF AEROPONICS)

In parallel with world population growth, demand for healthy and clean agricultural products is increasing day by day. To satisfy expected increases in agricultural products within traditional methods becomes more and more difficult, considering the climate change and soil degradation. There is a need to adopt and develop innovative agricultural practices. One of the most effective and new methods that can be used is Aeroponics. Aeroponics is a process of growing plants, within a controlled environment, in the absence of soil, with a small amount of water, using a minimum area of 3-dimensional greenhouse farming, where the cultivation period, compared to the traditional, is faster and prolonged throughout the year. Regarding this matter, we find it reassuring, that Georgian companies are not lagging behind the current global processes and are actively involved in refining or developing the Aeroponics system. The advantages of Aeroponics over the traditional method (Geoponics) can be classified as follows: • Requires less water. • Plant fertility does not depend on soil quality, or weather conditions. moreover, soil is not required at any stage of plant vegetation. • Has the highest vegetation per square meter compared to all other existing methods (Geoponics, Hydroponics), which is due to the possibility of 3-dimensional farming in Aeroponics. • Reduces transportation cost, since greenhouses can be organized directly in the cities and in urban areas. • The plans can be planted all year round regardless of meteorological conditions and seasonality. • Since nutrients and minerals are systematically provided to the plants’ roots, the process of its growth and consequently fertility lasts longer than the traditional method. As for disadvantages of using Aeroponics can be summarize as following: • At the beginning stage, set up costs of all components for the Aeroponics are relatively high. • Aeroponics requires specialized knowledge not only regarding the needs for plants, but also of the whole electronic systems and tools, which are widely used in Aeronautics (for example: pH / EC / humidity meter, timers, high pressure atomizers, etc.) • Even minor mistakes can have negative effect. Specifically, if the plants do not get exactly as many vital minerals as needed, they will not survive. As already mentioned, soil is not used in Aeronautics which would neutralize excess minerals or nutrients. In conclusion, Aeroponics is the one of the most innovative and efficient ways of farming, which promises sustainable future production of the agricultural products. Furthermore, Aeroponics has minimal or no negative impact on the environment, while traditional farming uses water and land resources insufficiently.

Hydroponics Fodder Grow Chamber

India is a developing country, but rural areas do not seem to be developing much. Basically most of the public is farmers, most of the farmers have limited agricultural land and also lack of water resources. in many parts of India rain and is not enough for traditional way farming. To avoid these problems our proposed system is structured a helpful touch of fresh and raw feed for cattle food within affordable natural conditions. This hydroponic system does not require any soil to grow fodders and will absorb 80% less water as compared to the traditional method of farming. Greater topic for work to upgrade the Hydroponic Fodder Grow room for proper management of cattle fodder in any period during the year. This paper suggests a clever plan no human power or less human power is required for It performance. this is usually a completely automated system. In seven to for eight days the room provides fodder as a ready-to-feed product any cattle or grass-eating animals. This process is aided by a Moisture sensor to produce a certain amount of water. Forage seeds use H2O, or solutions that enrich the nutrients of the drug food within the absence of soil. The amount of water is additionally calculated by microcontroller atmega328p. Also, we visit the average temperature and humidity of our room. This heat and humidity are the same and is controlled by a cool cooler and UV/LED light inside the room. Adequate water management and nutrients within the hydroponic system, moisture, humidity pH, water level and temperature should be measurement Using a microcontroller all these functions do it automatically and display at the top of the guided screen. These hydroponics require less space, and this is true usually inside a room of aluminum or fiber. that the environment of the room is completely controlled. That's the fodder prepared for use within 8 days up to 1fit This healthy cattle fodder. Mainly more production we use maize as fodder. Performing remote monitoring of fodder extension procedure, prohibited by employees, thereby reducing the manual process.

Evaluating the infiltration capacity of degraded vs. rehabilitated urban greenspaces: Lessons learnt from a real-world Italian case study

Climate change (higher frequency and intensity of precipitation events) and land use change (urbanization reducing soil drainage capacity) are increasingly causing stormwater problems globally, especially in cities. Nature-based solutions such as urban greenspace rehabilitation programs are gaining considerable attention for restoring soil retention capacity and protecting cities against increasing flood risk. However, a better understanding of how effective such measures are in practice is needed to enable and promote their adoption across urban settings.To this end, in this study, we assess the effect of soil rehabilitation measures in terms of soil compaction, vegetation cover and unsaturated hydraulic conductivity by analysing the results of an infiltration measurement campaign conducted across a wide range of real-world greenspaces (from recently rehabilitated, to poorly maintained, down to highly degraded) in the Italian city of Milan, one of the most urbanized areas in Europe.Our results show that the unsaturated hydraulic conductivity varies significantly across the examined greenspaces, due to differences in time from rehabilitation, soil compaction and vegetation cover. Specifically, we find that the highest unsaturated hydraulic conductivity is obtained after approximately 5 years since implementation of soil rehabilitation measures, which can be explained by the time needed (i) by the introduced vegetation to develop root systems, and (ii) by the soil matrix to develop a coherent structure that allows stable connections between pores and thus the strengthening of preferential water pathways. Finally, our study shows that, in absence of soil and vegetation maintenance, unsaturated hydraulic conductivity may decrease rapidly after about 9–12 years.These findings provide useful information for supporting the planning of nature-based solutions in practice, which will become increasingly important to protect our cities from climate change impacts and widespread urbanization going forwards.

Efficacy of Disinfectants against Fusarium oxysporum f. sp. cubense Tropical Race 4 Isolated from La Guajira, Colombia.

Banana, the main export fruit for Colombia, is threatened by Fusarium wilt (FWB), caused by Fusarium oxysporum f. sp. cubense (Foc), tropical race 4 (TR4). Pathogen containment through disinfecting tools, machinery, shoes, and any means that may carry contaminated soil particles with proper disinfectants is at the forefront of disease management. In this study, the biocide efficacy of 10 commercial quaternary ammonium compounds (QACs) products and one based on glutaraldehyde (GA) were evaluated on both reproductive structures (microconidia and macroconidia) and survival spores (chlamydospores) of Foc TR4 (strain 140038) isolated from La Guajira, Colombia. QACs were evaluated at 1200 ppm and two exposure times: <1 and 15 min in the absence or presence of soil. For GA disinfectant, four different concentrations (500, 800, 1200, and 2000 ppm) were evaluated at both contact times in the presence of soil. In the absence of soil, all QACs showed 100% biocidal efficiency against microconidia, macroconidia, and chlamydospores at both <1 and 15 min. The presence of soil decreased the efficacy of disinfectants, but some of them, such as QAC3_1st, QAC7_4th, and QAC5_4th, showed 98%, 98%, and 100% efficacy against Foc TR4 chlamydospores, respectively, after <1 min of contact time. For instance, the GA-based disinfectant was able to eliminate all Foc TR4 propagules after 15 min for all concentrations tested.

Richness of Rhizosphere Organisms Affects Plant P Nutrition According to P Source and Mobility

Plants evolve complex interactions with diverse soil mutualist organisms to enhance P mobilization from the soil. These strategies are particularly important when P is poorly available. It is still unclear how the soil P source (e.g., mineral P versus recalcitrant organic P) and its mobility in the soil (high or low) affect soil mutualist biological (ectomycorrhizal fungi, bacteria and bacterial-feeding nematodes) richness—plant P acquisition relationships. Using a set of six microcosm experiments conducted in growth chamber across contrasting P situations, we tested the hypothesis that the relationship between the increasing addition of soil mutualist organisms in the rhizosphere of the plant and plant P acquisition depends on P source and mobility. The highest correlation (R2 = 0.70) between plant P acquisition with soil rhizosphere biological richness was found in a high P-sorbing soil amended with an organic P source. In the five other situations, the relationships became significant either in soil conditions, with or without mineral P addition, or when the P source was supplied as organic P in the absence of soil, although with a low correlation coefficient (0.09 &lt; R2 &lt; 0.15). We thus encourage the systematic and careful consideration of the form and mobility of P in the experimental trials that aim to assess the role of biological complexity on plant P nutrition.

Effect of outdoor open pack space allowance on the behavior of freestall-housed dairy cows

Providing dairy cows access to pasture is desirable, given their strong motivation for pasture access, but this practice is hindered by several practical constraints, including lack of available pasture. An alternative to pasture is an outdoor area that is bedded with a soft material such as sand or wood chips that requires less space than pasture, given the absence of soil or grass that can otherwise be damaged by cow traffic. However, little is known about space requirements for alternative outdoor areas. This study investigated how space allowance affected cow preference to be outdoors as well as cow behavior on an outdoor pack. A total of 3 groups of 24 pregnant, lactating, healthy Holstein cows were used. Each group was given 3 d for social dynamics to stabilize; during this time cows were kept indoors in a freestall pen. A habituation phase of 5 d followed, where animals were given free access to the outdoor pack with a space allowance of 16 m2/cow. Cows were moved outside (if not already outdoors) at set times each day during the habituation phase (i.e., 5 times during the first 2 d and 2 times during the last 3 d). Cows were then given free access to the outdoor pack, but space allowance was changed every day. A total of 13 different space allowances were randomly applied, without replacement, ranging from 4 to 16 m2/cow in 1-m2 increments. Using continuous video recordings, the location of the cows (i.e., in the freestall barn or on the outdoor pack) as well as displacements from a lying position on the outdoor pack were scored. Standing and lying behaviors were automatically measured using HOBO data loggers (Onset, Cape Cod, MA). Over the 24-h period, cows spent more time outside with increasing space allowance, but this result was driven almost entirely by the increased time spent outdoors during the nighttime hours. During the night, space allowance did not influence the number of displacements from lying on the outdoor pack or the proportion of time on the outdoor pack that cows spent lying down. Our results indicate that cows use an outdoor bedded pack mostly at night and that the time spent outside at night increases with increasing space allowance. Providing an outdoor bedded pack should be considered when designing dairy cattle housing systems.

Modeling arsenic content in Brazilian soils: What is relevant?

Arsenic accumulation in the environment poses ecological and human health risks. A greater knowledge about soil total As content variability and its main drivers is strategic for maintaining soil security, helping public policies and environmental surveys. Considering the poor history of As studies in Brazil at the country's geographical scale, this work aimed to generate predictive models of topsoil As content using machine learning (ML) algorithms based on several environmental covariables representing soil forming factors, ranking their importance as explanatory covariables and for feeding group analysis. An unprecedented databank based on laboratory analyses (including rare earth elements), proximal and remote sensing, geographical information system operations, and pedological information were surveyed. The median soil As content ranged from 0.14 to 41.1 mg kg−1 in reference soils, and 0.28 to 58.3 mg kg−1 in agricultural soils. Recursive Feature Elimination Random Forest outperformed other ML algorithms, ranking as most important environmental covariables: temperature, soil organic carbon (SOC), clay, sand, and TiO2. Four natural groups were statistically suggested (As content ± standard error in mg kg−1): G1) with coarser texture, lower SOC, higher temperatures, and the lowest TiO2 contents, has the lowest As content (2.24 ± 0.50), accomplishing different environmental conditions; G2) organic soils located in floodplains, medium TiO2 and temperature, whose As content (3.78 ± 2.05) is slightly higher than G1, but lower than G3 and G4; G3) medium contents of As (7.14 ± 1.30), texture, SOC, TiO2, and temperature, representing the largest number of points widespread throughout Brazil; G4) the largest contents of As (11.97 ± 1.62), SOC, and TiO2, and the lowest sand content, with points located mainly across Southeastern Brazil with milder temperature. In the absence of soil As content, a common scenario in Brazil and in many Latin American countries, such natural groups could work as environmental indicators.