Accumulation of Potentially Toxic Metals in Egyptian Alluvial Soils, Berseem Clover (Trifolium alexandrinum L.), and Groundwater after Long-Term Wastewater Irrigation

The reduced availability of water resources in Egypt has imposed the need to intensify the use of wastewater for crop irrigation in the alluvial soils of anthropogenic origin. Relevant effects can derive from contents of potentially toxic metals (PTMs) in supply resources soils, crops, and groundwater in these areas. For this reason the PTM content has to be monitored to evaluate and minimize health hazards. Therefore, in this context, two areas of the SE Nile Delta subjected to 25 year of wastewater irrigation, using agricultural drainage water (ADW) and mixed wastewater (MWW) were chosen and compared with a nearby site irrigated with Nile freshwater (NFW). At each of the three sites, ten samples of irrigation water, topsoil, berseem clover (Trifolium alexandrinum L.) plants, and seven groundwater samples were collected and analyzed for Cr, Co, Cu, Pb, Ni, and Zn. Results indicate that the total contents of Co, Cu, Ni, and Zn in soils collected from the three sampling sites and Pb in the MWW-irrigated soils were higher than their average natural contents in the earth’s crust, indicating potential risks. The DTPA-extractable contents of Cu in the three sites, in addition to Pb and Zn in the MWW-irrigated soils, exceeded the safe limits. The MWW-irrigated soils showed a considerable degree of metal contamination, while the NFW- and ADW-irrigated soils showed moderate and low levels of contamination, respectively. The contents of the six PTMs in the three sites showed low individual ecological risks, except for Pb in the MWW-irrigated soils that showed a moderate risk; however, the overall ecological risk remained low in all samples. The values of Co, Cu, and Ni in berseem shoot in addition to Pb from the MWW-irrigated soils were over the maximum permissible levels for animal feeding. Values of root-to-shoot translocation factor were lower than 1.0 for Cr, Co and Ni but higher than 1.0 for Cu, Pb, and Zn. Berssem plant is a good candidate for phytofiltration of Cr, Co and Ni, while for extracting Cu, Pb and Zn from polluted soils. The groundwater samples collected from the three sampling sites showed lower metal concentrations than the safe limits for drinking standards. Further remediation studies should be taken into account to alleviate potential environmental and health-related risks when using supply resources different from freshwater.

Hospital wastewater treated with a novel bacterial consortium (Alcaligenes faecalis and Bacillus paramycoides spp.) for phytotoxicity reduction in Berseem clover and Tomato crops

Hospital wastewaters are produced in large amount in Pakistan (∼362–745 L/bed.day) and are discharged without proper treatment. They are widely used by farmers for crop irrigation and induce a phytotoxic effect on plant growth. The study was conducted to evaluate the effect of untreated and treated hospital wastewater on seed germination of a fodder crop Trifolium alexandrinum (berseem clover) and a food crop Solanum lycopersicum (tomato). A bacterial consortium was formed with three bacterial strains, i.e., Alcaligenes faecalis and Bacillus paramycoides spp., which were individually proven efficient in previous studies. The concentrations of untreated and treated hospital wastewater (25, 50, 75 and 100%) were used to irrigate these crop seeds. To assess the efficiency of treatment, the germination percentage (GP), delay index (DI), germination index (GI), stress tolerance indices (STIs), seedling vigour index (SVI) and phytotoxicity index (PI) were calculated and were statistically proven significant. The seeds grown in treated wastewater concentrations showed negative values of Phytotoxicity indices (tomato: −0.36, −0.47, −0.78 and −1.11; berseem clover: −0.23) which indicate a stimulatory or non-toxic effect on seedling growth. Our work proposes that this bacterial consortium is efficient for hospital wastewater treatment before crop irrigation.

Incorporating a Fresh Mixed Annual Ryegrass and Berseem Clover Forage Into the Winter Diet of Dairy Cows Resulted in Reduced Milk Yield, but Reduced Nitrogen Excretion and Reduced Methane Yield

The winter diet of dairy cows in Mediterranean climate regions is usually a total mixed ration with a base of conserved summer crops such as corn silage and alfalfa hay. However, there is increased labor and financial cost related to this kind of feeding, which could be reduced if fresh forages were used in place of some of the conserved forage in the cow diet. The objective of our study was to evaluate the effect of including fresh mixed annual ryegrass and berseem clover into the diet of dairy cows on milk, nitrogen utilization, and methane emission. Twenty-four lactating dairy cows were split into two groups and offered either a diet similar to that usually offered to the cows (CON) or one where a mixture of fresh annual ryegrass and berseem clover was used to partially substitute the corn silage and alfalfa hay in the diet (MIX). Milk yield was recorded automatically, and methane emissions were estimated using the SF6 tracer technique. The MIX diet had lower crude protein concentration (148 vs. 170 g/kg DM) but higher DM digestibility (81.6 vs. 78.6%) than the CON diet. Compared to the cows offered the CON diet, milk yield was reduced when cows were fed the MIX diet (36.4 vs. 31.9 kg/d), but methane emissions (381 vs. 332 g/d) and nitrogen excretion were also reduced (238 vs. 180 g/d). Nitrogen use efficiency was unaffected (30.8%). In addition, milk from cows fed the MIX diet had a fatty acid profile considered to be more beneficial to human health than that of the milk from cows fed the CON diet. Increasing the protein concentration in the MIX diet, either by direct supplementation or increasing the proportion of legume in the mixed herbage, could overcome the reduction on milk and positively affect methane emission and N use efficiency.

PSVIII-26 Extending the grazing season for grass-fed beef production into the spring transition period

In the Gulf Coast region, the spring transition period is a 45–60 d period between late April and mid-June. Red and white clovers’ growth pattern is delayed compared to winter grasses making them suitable for this transition period; however, an appropriate rest period allowing stockpiling is needed. Three treatments were evaluated on pastures planted in September of three consecutive years: 1) grazed until mid-February (MF); 2) grazed until first week of March (EM); and 3) grazed until last week of March (LM). Grazing re-started on May 1. Pasture was a mixed of annual ryegrass, red, white and berseem clover. Each year, 24 crossbred steers (330 ± 11 kg) were blocked by BW, allotted to 1 of 6 groups (2 replicates/treatment), and continuously stocked at 995 kg BW/ha. Forage mass at the beginning of the grazing period was greater (P < 0.05) in MF, followed by EM and LM. This represented a forage allowance of 2.0, 1.6, and 1.1 kg DM/kg BW. On d0, the proportion of annual ryegrass was greater (P < 0.05) in MF than in EM and the smallest in LM. Proportion of clovers was greater (P = 0.04) in EM in Year 2 while MF and LM were similar but greater for MF in Year 1. Berseem clover represented 59% of the clover biomass in MF while red clover was 72% of the clover biomass in LM. Proportion of clovers decreased with time while annual ryegrass became mature affecting its palatability. Steers that grazed on MF and EM had greater ADG (1.83 and 1.71 kg) than those on LM (1.41 kg). Grazing season was longer (P = 0.03) for MF (66 days) than for LM (39 days) while EM was intermediate (50 days). A rest period from early March to late April would allow grazing of high-quality pastures during the spring transition period.