Dairy Effluent-Saturated Biochar's Short-Term Effects on Vigna unguiculata and Cynodon dactylon Performance and Soil Properties.

We compared the effects of wood-, manure-, and blend-derived biochar (BC) saturated/unsaturated with dairy effluents on Vigna unguiculata and Cynodon dactylon performance and soil characteristics in a greenhouse pot study. Plant samples were assayed for herbage and root dry weight and N and C percentages. Soil samples were assayed for nutrients, pH, and conductivity. Variance analysis, Tukey's tests, Pearson's correlations, and multiple regression analysis were performed. The performance of C. dactylon was not affected. V. unguiculata's herbage and root production responded negatively to manure BC and 2% of any BC, respectively, which is mainly explained by the conductivity and soil P increase, respectively. When V. unguiculata was grown, BC inclusion decreased NO3-N and increased the soil P content. When C. dactylon was grown, only P was altered (increased) when manure or the blend BC were applied. The soil total C increased as the BC loading rate increased. The application of high BC rates was detrimental for V. unguiculata, but showed a neutral effect for C. dactylon. To improve dairy waste recycling, saturated 1% blend BC and saturated 2% blend or manure BC could be applied to V. unguiculata and C. dactylon, respectively, with no short-term negative impacts. Only wood BC avoided soil P build-up. BC application increased the soil total C, showing potential for C sequestration.

Biochar and Dairy Manure Amendment Effects on Cynodon dactylon Performance and Soil Properties.

Studies have determined the separate effects of biochar (BC) and manure application on forage species and soil, but few examined the effects of BCs made from different feedstock applied along with dairy manure. We compared the effect of wood- and manure-derived feedstock BC as well as dairy manure amendment application on Cynodon dactylon performance and soil properties in sandy loam and clay loam soils in a greenhouse pot study. Plant samples were assayed for herbage and root dry weight as well as herbage and root N and C percent and yield. Soil samples were assayed for macronutrients, micronutrients, metals, pH and conductivity. Data analyses involved variance analysis and Tukey's tests using R in RStudio (the IDE). In general, C. dactylon yields or mineral content were not affected by either manure or BC. However, an increase in the total herbage dry weight (30%) and in herbage N% (55%) was observed for clay loam and sandy loam soil, respectively, due to manure amendment application. There were no alterations in clay loam NO3-N and P due to any treatment; however, in sandy loam, these nutrients were not altered only when wood BC was applied. In sandy loam soil, NO3-N and P increased when manure BC along with dairy manure and when manure BC alone were applied, respectively. Thus, wood BC application should be considered to avoid these nutrient buildups when dairy manure is used as a soil amendment. This research shows a neutral (BC) or positive (dairy manure amendment) impact on C. dactylon performance. BC incorporation increases soil total C, showing potential for C sequestration. Long-term field trials could corroborate plant performance and soil parameters.

Ferroptosis precedes apoptosis to facilitate specific death signalling by fatty acids.

Cell death is physiologically induced by specific mediators. However, our power to trigger the process in selected cells is quite limited. The protandric shrimp Hippolyte inermis offers a possible answer. Here, we analyse a de novo transcriptome of shrimp post-larvae fed on diatoms. The sex ratio of diatom-fed shrimps versus shrimps fed on control diets was dramatically altered, demonstrating the disruption of the androgenic gland, and their transcriptome revealed key modifications in gene expression. A wide transcriptomic analysis, validated by real-time qPCR, revealed that ferroptosis represents the primary factor to re-shape the body of this invertebrate, followed by further apoptotic events, and our findings open biotechnological perspectives for controlling the destiny of selected tissues. Ferroptosis was detected here for the first time in a crustacean. In addition, this is the first demonstration of a noticeable effect prompted by an ingested food, deeply impacting the gene networks of a young metazoan, definitely determining its future physiology and sexual differentiation.

The dissemination of antibiotics and their corresponding resistance genes in treated effluent-soil-crops continuum, and the effect of barriers.

Irrigation with treated effluent is expanding as freshwater sources diminish, but hampered by growing concerns of pharmaceuticals contamination, specifically antibiotics and resistance determinants. To evaluate this concern, freshwater and effluent were applied to an open field that was treated with soil barriers including plastic mulch together with surface and subsurface drip irrigation, cultivating freshly eaten crops (cucumbers or melons) for two consecutive growing seasons. We hypothesized that the effluent carries antibiotics and resistance determinants to the drip-irrigated soil and crops regardless of the treatment. To test our hypothesis, we monitored for antibiotics abundance (erythromycin, sulfamethoxazole, tetracycline, chlortetracycline, oxytetracycline, amoxicillin, and ofloxacin) and their corresponding resistance genes (ermB, ermF, sul1, tetW, tetO, blaTEM and qnrB), together with class 1 integron (intl1), and bacterial 16S rRNA, in water, soil, and crop samples taken over two years of cultivation. The results showed that an array of antibiotics and their corresponding resistance genes were detected in the effluent but not the freshwater. Yet, there were no significant differences in the distribution or abundance of antibiotics and resistance genes, regardless of the irrigation water quality, or crop type (p > 0.05), but plastic-covered soil irrigated with effluent retained the antibiotics oxytetracycline and ofloxacin (p < 0.05). However, we could not detect significant correlations between the detected antibiotics and the corresponding resistance genes. Overall, our findings disproved our hypothesis suggesting that treated effluent may not carry antibiotics resistance genes to the irrigated soil and crops yet, plastic mulch covered soil retain some antibiotics that may inflict long term contamination.

Occurrence and distribution of antibiotics and corresponding antibiotic resistance genes in different soil types irrigated with treated wastewater.

Diminishing freshwater (FW) supplies necessitate the reuse of treated wastewater (TWW) for various purposes, like irrigation of agricultural lands. However, there is a growing concern that irrigation with TWW may transfer antibiotic resistance genes (ARGs) to the soil and crops. We hypothesized that TWW irrigation would increase the prevalence of antibiotic residues together with the corresponding ARGs in the irrigated soil. We further predicted that soil texture, especially pH, clay content, and organic matter variabilities, would change the antibiotic residues concentrations and thus ARGs dissemination. To test our predictions, three soils types (loamy-sand, loam, and clay) were irrigated with two water types (FW and TWW), over two consecutive seasons. We monitored physico-chemical parameters, the abundance of seven antibiotic residues, and their corresponding ARGs together with class 1 integron (intI1) in 54 water and soil samples collected at the end of the field experiments. The results revealed increase in antibiotics concentrations and ARGs relative abundance in TWW than FW. Yet, in the soil ARGs relative abundances were independent of the irrigation water quality, but dependent on the soil type, especially the clay content. Further, there were no clear associations between the targeted antibiotics or the presence of heavy metals and ARGs' relative abundance in the water or soil samples. Therefore, our results question the link between the discharge of antibiotics and heavy metals, and the dissemination of ARGs in soil environments.

The fate of pathogens in treated wastewater-soil-crops continuum and the effect of physical barriers.

Secondary treated wastewater (TWW) could provide a cheap and sustainable alternative to potable water (PW) irrigation and ensure food security, especially in arid and semi-arid regions. However, TWW may pose a health risk by introducing pathogens to the irrigated soil and crop, and especially to irrigated vegetables that are eaten raw. To avoid contamination, national and international authorities have mandated the use of physical barriers, such as drip irrigation and plastic mulch, to separate the irrigation water and the crops. Although the barriers are mandated, it is not clear whether they prevent contamination of crops. To evaluate the role of barriers on crop safety, cucumbers and melons were cultivated in a field irrigated with TWW or PW with the application of barriers including surface and subsurface drip irrigation and plastic mulch. Over 500 samples of water, soil and the model crops (surface and tissue) were collected during two growing seasons and used to monitor fecal indicator bacteria and pathogens using culture dependent and independent methods. The results showed that there were no statistically significant differences in both the fecal indicator and the pathogen abundance between treatments in either the soil or the crops, regardless of the water quality or barrier applied, even though TWW supported higher diversity and abundance of indicators and pathogens than PW. Moreover, the microbial communities detected in the irrigated soils and crops could not be linked to the irrigation water. The obtained results suggest that irrigation with TWW does not result in fecal pathogen contamination of the irrigated soil or crops.

Importance of soil texture to the fate of pathogens introduced by irrigation with treated wastewater.

World-wide water scarcity is urging the use of treated wastewater (TWW) for irrigation but this practice may have adverse effects on soil and crop contamination due to the introduction of potential microbial pathogens. The objective of this study was to evaluate the potential health risks caused by TWW irrigation of soils differing in their texture, i.e., soil particle fractions including sand, silt and clay. We predicted that the presence of fecal indicator bacteria (FIB) and pathogens would not be linked to TWW irrigation, yet their abundance would be favored by the smallest soil fraction (~2 nm, e.g., clay) as it provides the largest surface area. To test our hypotheses, culture dependent and independent techniques were used to monitor the presence, abundance and source of FIB and microbial pathogens (bacteria and protists) in water (TWW and potable water) and three irrigated soil types (clay, loam and loamy-sand) in a field study spanning two years. The results showed that FIB and pathogens' abundance were significantly different between water types, yet these differences did not carry to the irrigated soils. The abundance and presence of FIB and potential opportunistic or obligate human pathogens did not significantly differ (p > 0.05) between TWW and potable water irrigated soils. Moreover, the source of the FIB and potential pathogens could not be linked to irrigation with TWW. Yet, soil type significantly altered the potential pathogens' diversity (p < 0.05) and abundance (p < 0.05), and differences were affected by clay content, as predicted. The results gave no indication for potential adverse health effects associated with the application of TWW but demonstrated that clay has a particular stabilizing effect on the potential presence of microbial pathogens.