Effects of solid manure particle fractionation on transport, retention, and release of Escherichia coli

Understanding the effect of manure particle fractionation on transport, retention, and release of bacteria plays a critical role in manure management and environmental policies that address soil and water bacterial pollution. Compared to soil particle size, there is less understanding of the importance of solid manure particle size and fractionation on bacterial fate and transport in soils. Four different cow manure particle sizes (0.25, 0.5, 1, and 2 mm) were used to investigate Escherichia coli fate in a saturated loamy sand soil. Leaching experiments were performed for up to 20 pore volumes. Preferential transport of chloride mitigated as manure particle size increased. The larger manure fractions (1 and 2 mm) showed greater heterogeneity in bacteria transport and release; smaller manure fractions (0.25 and 0.5 mm) had a greater bacteria retention with retarded release. Bacteria release was associated with transport and re-entrainment of manure particles through soil columns. The results highlighted the contribution of fine and transported particles as of primary importance for retention near the surface and transporting bacteria in soil. Similar retention shapes (i.e., exponential) for different fractions illustrated the similarity of manure source, where greater retention was observed at 0−3 cm depth for the smallest (0.25 mm) and largest (2 mm) manure fractions. The findings also highlighted the dependency of bacteria transport, retention, and release on manure physical fractionation, which should be considered in managing soil and manure practices in the field. © 2021 The Author

Particle fractionation controls Escherichia coli release from solid manure

Bacteria transport through soil is a complex process particularly when the cells are released from solid manures and co-transported with particles. This study focuses on understanding of the Escherichia coli release from different particle fractions (0.25-, 0.5-, 1-, and 2-mm) of solid manure and evaluating different influent boundary conditions during cell release from manure and when a solid manure is applied to the soil. The 0.25-mm and 2-mm particle sizes resulted a greater cell release compared to 0.5-mm and 1-mm fractions (p < 0.05). The shape and magnitude of the cell release curves (CRCs) from the original manure bulk were mainly influenced by the two 0.25-mm and 2-mm fractions, respectively. The arithmetic mean for normalizing the CRCs and the time variable- based normalized CRCs for the manure-treated soil were the robust variables in evaluation of the experimental data. However, a single maximum bacteria concentration could provide the realistic dataset for the modeling process. Evaluation of the root-mean-squared-error and Akaike criterion showed that the two- and three-parametric models are recommended for simulating the cell release from solid manure in comparison with one parametric models. This study also suggests considering separate microbial release evaluations, with regards to influent concentration, for manure and manure-treated soils to propose best management practices for controlling bacteria pollution. Further research will reveal the key roles of different woody components and soluble material ratios for the various solid manures in bacteria release

Particle fractionation controls Escherichia coli release from solid manure

Funding Information: This work was supported by Shahrekord University . Nasrollah Sepehrnia was supported by Alexander von Humboldt Foundation and Postdoctoral Fellowship at Leibniz University of Hannover, Germany. Publisher Copyright: © 2021 The Author(s)Peer reviewedPublisher PD

EFFECTS OF SDI FILTRATION ON WASTEWATER QUALITY FOR IRRIGATION

In order to assessment of SDI system application in the condition of wastewater reuse, three treatments with three replications were design. These treatments included check treatment with drinking water (CH), surface drip irrigation with wastewater (DI) and subsurface drip irrigation with wastewater (SDI). In addition, before pipeline, a SDI filtration designed to improve biological index of wastewater. The results of this research showed that the BOD5, TSS and nitrogen component decreased during filtration acceptably. But the microbiological factors didn’t improve completely. In this condition, injection of wastewater below the soil surface (SDI system) could decrease the surface microbiological pollution significantly as compare to CH. In concluded the SDI system recommended in the wastewater reuse condition and application of new system of drilling considered for installing, monitoring and maintenance of SDI

Physiological responses of pepper plant (Capsicum annuum L.) to drought stress

Water shortage is the most important factor constraining agricultural production all over the world. New irrigation strategies must be established to use the limited water resources more efficiently. This study was carried out in a completely randomized design with three replications under the greenhouse condition at Shahrekord University, Shahrekord, Iran. In this study, the physiological responses of pepper plant affected by irrigation water were investigated. Irrigation treatments included control (full irrigation level, FI) and three deficit irrigation levels, 80, 60 and 40% of the plant’s water requirement called DI80, DI60, and DI40, respectively. A no plant cover treatment with three replications was also used to measure evaporation from the soil surface. Daily measurements of volumetric soil moisture (VSM) were made at each 10 cm intervals of the soil column, considered as a layer. The differences between the measured VSM and the VSM in the next day and evaporation rate at the soil surface at the same layer of the no plant cover treatment were calculated. Eventually, by considering the applied and collected water in each treatment, evapotranspiration (ETC) and root water uptake (RWU) in each layer per day were estimated. Furthermore, fruit number per plant, fresh fruit weight/day, root fresh/dry weight, shoot fresh/dry weight, root zone volume, root length and density, crop yield, and water use efficiency (WUE) were measured under different water treatments. The results showed that the maximum and minimum of all the studied parameters were found in the FI and DI40 treatments, respectively. ETC in the DI80, DI60, and DI40 treatments were reduced by 14.2, 37.4, and 52.2%, respectively. Furthermore, applying 80, 60, and 40% of the plant’s water requirement led to crop yield reduction by 29.4, 52.7, and 69.5%, respectively. The averages of root water uptakes (ARWUs) in the DI80, DI60, and DI40 treatments reduced by 17.08, 48.72, and 68.25%, respectively. WUE and crop yield also showed no significant difference in the FI and DI80 treatments. Moreover, in the DI80 treatment the reduced rate of water uptake was less than the reduced rate of plant's applied water. According to these results, it can be concluded that 20% deficit irrigation had no significant reduction on the yield of pepper, but above this threshold, there was an adverse effect on the growth and yield. Therefore, for water management in the regions with limited water resources, plant's applied water can be decreased around 20%.12 month embargo; Accepted author version posted online: 25 Jan 2017This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Hydrodynamics and transverse mixing in a rectangular channel with bed forms and bank vegetation

The analysis of contaminants mixing in natural channels is an important topic of Environmental Hydraulics. In the mid-field, the prediction of transverse mixing is complicated by other typical features of natural channels, such as bed forms and vegetation. The present experimental research investigated the effects of bedforms and banks vegetation on the structure of the turbulent flow field and on the transverse mixing process in a channel. A flume equipped with a set of ten 2D fixed dunes on the bed and rice stems at the banks was used. Detailed velocity measurements were performed using acoustic Doppler velocimetry. Mixing measurements were made using a NaCl solution as the tracer and measuring its concentration downstream the point of injection. The results showed that dunes and vegetation have a significant effect on the flow field and on transverse mixing coefficient Dt-y . Comparing with the flat bed conditions, the presence of dunes and vegetation at the channels banks significantly modified the flow field and increased the strength of secondary currents. Finally, the presence of vegetation on channel banks increased the transverse mixing as compared with dunes without vegetation

Effects of Lateral Spacing in Tape Irrigation System on Salinity Distribution in Soil Profile under Wheat Cultivation

Introduction In arid and semi-arid regions, agricultural sustainability needs to improve the consumption of water and soil resources. Low rainfall, high evaporation, low water quality and less leaching of solutes in the soil due to limited water resources are the main problems in these areas. The quality of water and soil resources in the provinces of Fars, Khuzestan, Yazd, Golestan and Khorasan also shows that most of the wheat farming lands in these provinces are always facing salinity issues. According to the conducted studies, saline water can be successfully used in irrigation, but application of unconventional water by surface irrigation systems with low efficiency due to evaporation and high water salts leads to soil salinity. Micro-irrigation methods increase water use efficiency by reducing water consumption and increasing yield, so that drip irrigation efficiency of 91-80% and irrigation levels of 50-73% have been reported. In recent years, the use of drip irrigation system (such as tape on wheat fields) has been recommended to farmers as a water management solution. Micro-irrigation systems by reducing water consumption and increasing yields, improve water use efficiency. Drip tape irrigation system compared to other surface and sprinkler irrigation methods, due to short irrigation periods and reduction of evaporation losses and deep infiltration even for crops can be proposed as an alternative. Drip tape irrigation in wheat cultivation can increase water use efficiency up to 2 times. Also, in irrigation with salt water, while maintaining humidity in the environment, it reduces salinity stress and by consuming less water and reducing the amount of wetting, it introduces less solutes into the soil. This method has limitations in wheat fields due to costs and also the possibility of soil salinity problems, some of which can be overcome by increasing the distance between the laterals and reducing the consumption of drip irrigation (Tape) per unit area.Materials and Methods  In this study, during the 2020-2021 at the Salinity Research Center of Yazd Province (Iran), the effect of lateral distances on the surface and depth distribution of soil salinity was investigated. For this purpose, two irrigation water salinity treatments, including 3 and 8 dS / m and two flood (T1) and drip irrigation systems (Tape) with lateral distances of 60 (T2), 100 (T3) and 140 (T4) cm were considered. Irrigation management treatments included the use of the flooding method (as the dominant method in wheat fields) and the use of the Tape drip irrigation method (as the proposed method with very low water consumption). A distance of 60 cm was considered as the optimal distance with complete water overlap, a distance of 100 cm was considered as an economic distance with the possibility of deep moisture distribution and a distance of 140 cm was considered as a large lateral distance. To investigate the salinity distribution and the accumulation of salts in the soil, regular soil sampling of different treatments was the end of the season.Results and Discussion In all irrigation treatments (saline and non-saline), despite the constant volume of water consumption per unit area of all treatments, in T3 and T4 treatments, irrigation depth increased compared to T2 treatment and reduced soil salinity in the wetting area (irrigated area). By increasing the horizontal distance of each point of the field from the lateral, the irrigation depth and leaching fraction decrease and consequently, the soil salinity of these points can also increase. Under non-saline irrigation conditions (salinity of 3 dS/m), soil salinity at intervals of zero (below the lateral), 15 and 30 cm, between 5.5 and 6.1 dS/m has been observed. Values below the threshold of tolerance to salinity of wheat plant and, in this regard, does not pose a risk to the plant. At a distance of 45, 60 and 70 cm from the water pipe, the salinity of the soil is higher than the threshold and if there is a plant in this area of the field, it will face serious damage.Conclusion  The results showed that although the Tape method in saline conditions (8 dS/m) compared to non-saline conditions (3 dS/m) leads to higher accumulation of solutes in the soil and increases the possibility of plant damage, but according to the final results of this study, by increasing the distances of irrigation laterals and proportionally increasing the depth of irrigation and keeping the salts away from the planting bed, a more suitable environment for plant growth can be prepared and higher economic benefits of this measure can be obtained. Also, in terms of controlling soil salinity, the conditions have been such that treatment with lateral distance of 140 cm compared to treatments of 60 and 100 cm has led to lower amounts of soil salinity in the subsurface and has provided better conditions for the plant. Thus, by increasing the distances of laterals from 60 to 140 cm and, consequently, increasing the depth of irrigation, it was possible to transfer solutes to lower depths of the soil

Effects of municipal wastewater on soil chemical properties in cultivating turfgrass using subsurface drip irrigation

Knowing the concentrations of the nutrient elements in soils is important due to their toxic effect on humans and the environment. The aims of this study were to assess the effects of water quality, depths and distances of lateral installation on soil chemical properties during turfgrass cultivation. A field experiment was conducted using a Split Split Plot design based on the Randomized complete Block (RCB) with two treatments (well’s and wastewater), and eight sub-treatments (45 and 60 cm distance of the laterals and 15, 20, 25, and 30 cm depths of laterals) in three replicates on a sandy-loam soil, in Shahrekord, Iran. Soil samples were collected from 0-30 and 30-60 cm depth for measuring nitrate (NO3-), electrical conductivity (EC), and pH at the end of the experiment. During the experiment, fecal coliform (FC) were also measured at the soil surface. Results indicated that by increasing lateral distance, NO3- level increased in both layers. With installing laterals in deeper levels, NO3- concentration decreased at the beginning, then increased in the first layer, whereas in the second layer NO3- concentration decreased. In addition, installing laterals in deeper depth, caused an increase in soil EC in the top layer, but a decrease in the lower layer. However, the results showed that there was no significant effect of experimental factors on soil pH. The results also show that with increasing laterals depth, Fc level decreased at the soil surface.12 month embargo; Published online: 04 Jan 2017This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]