Impact of Tetracycline on Microbial Communities in the Secondary Treatment Process of Wastewater Treatment Systems

This study examined the impact of the antibiotic tetracycline at environmentally relevant concentrations (1μg/L and 10μg/L) on the composition and function of the microbial community that are responsible for the secondary treatment step in a municipal wastewater treatment plant (MWTP). Specifically, this study examined whether nitrification is inhibited by the presence of tetracycline under high and low nutrient replacement conditions. Aerated semi-batch reactors were set up containing activated sludge samples from a MWTP. Reactors were replenished with a synthetic wastewater media at two constant replacement rates for a period of 4 weeks. Parameters such as ammonia, nitrate/nitrite and total Kjeldahl nitrogen concentrations were monitored to evaluate the nitrogen removal efficiency. Under a low nutrient replacement rate, tetracycline was observed to have a positive impact on ammonia removal and nitrification than at the higher one. However, total Kjeldahl nitrogen concentrations increased in low nutrient replacement reactors under the presence of tetracycline which suggested a potential inhibitory effect on denitrification. At high nutrient replacement rates, tetracycline did not demonstrate an inhibitory effect on both nitrification and denitrification processes. Overall, it appears that both antibiotic presence and nutrient replacement rates can influence the community composition and function of microbial communities found in a MWTP.

Impact of Tetracycline on Microbial Communities in the Secondary Treatment Process of Wastewater Treatment Systems

This study examined the impact of the antibiotic tetracycline at environmentally relevant concentrations (1μg/L and 10μg/L) on the composition and function of the microbial community that are responsible for the secondary treatment step in a municipal wastewater treatment plant (MWTP). Specifically, this study examined whether nitrification is inhibited by the presence of tetracycline under high and low nutrient replacement conditions. Aerated semi-batch reactors were set up containing activated sludge samples from a MWTP. Reactors were replenished with a synthetic wastewater media at two constant replacement rates for a period of 4 weeks. Parameters such as ammonia, nitrate/nitrite and total Kjeldahl nitrogen concentrations were monitored to evaluate the nitrogen removal efficiency. Under a low nutrient replacement rate, tetracycline was observed to have a positive impact on ammonia removal and nitrification than at the higher one. However, total Kjeldahl nitrogen concentrations increased in low nutrient replacement reactors under the presence of tetracycline which suggested a potential inhibitory effect on denitrification. At high nutrient replacement rates, tetracycline did not demonstrate an inhibitory effect on both nitrification and denitrification processes. Overall, it appears that both antibiotic presence and nutrient replacement rates can influence the community composition and function of microbial communities found in a MWTP.

Examination of resistance to Sclerotinia stalk and head rot in sunflower (Helianthus annuus L.) hybrids

Nowadays, phytopathogenic fungi cause the most serious yield loss in open field cultures, and sunflower (Helianthus annuus) is no exception to this phenomenon. Sclerotinia stalk and head rot (Sclerotinia sclerotiorum) is present in the whole area of Hungary, and can cause serious financial loss. In our experiment, sunflower hybrids were tested for resistance to Sclerotinia sclerotiorum infection. 16 sunflower hybrids were examined at the Experimental Breeding Site in Jászboldogháza. Pesticide treatment and also nutrient replacement were applied on the sunflower fields.

Describing Fusarium diseases on maize in 2013 using data from several production sites

As in other parts of the world, the frequency of weather extremes has increased greatly in Hungary in recent years. This means that maize production is faced with greater risks from all aspects: nutrient replacement, irrigation, plant protection. This is especially true of fusarium diseases. In a continental climate, the pathogens causing the most serious problems are species belonging to the Fusarium genus. They infect the ears, which – besides reducing the yield – poses considerable risk to both human and animal health due to the mycotoxins produced by them. Depending on which Fusarium species are dominant at a given location, changes can be expected in the level of infection and in the quality deterioration caused by the mycotoxins they produce. Fusarium spp. not only damages the maize ears but when pathogen attacks the stalk, the plant dies earlier, reducing grain filling and resulting in small, light ears. In addition, the stalks break or lodge, resulting in further yield losses from ears that cannot be harvested. The degree of infection is fundamentally determined by the resistance traits of the maize hybrids, but also a great role in that region Fusarium species composition as well.

Assessing Sediment-Nutrient Export Rate and Soil Degradation in Mai-Negus Catchment, Northern Ethiopia

Even though soil degradation challenges sustainable development, the use of degradation indicators such as nutrient export (NE) and nutrient replacement cost is not well documented at landform level. This study is aimed to investigate the extent of soil degradation, NE rates, and their replacement cost across landforms in the Mai-Negus catchment, northern Ethiopia. Different erosion-status sites (aggrading, stable, and eroded) in the landforms were identified, and soil samples were randomly collected and analysed. Nutrient export, replacement cost, and soil degradation were calculated following standard procedures. This study showed that soil degradation in the eroded sites ranged from 30 to 80% compared to the corresponding stable site soils, but the highest was recorded in the mountainous and central ridge landforms. Average NE of 95, 68, 9.1, 3.2, 2.5, and 0.07 kg ha−1 y−1 for soil calcium, carbon, nitrogen, potassium, magnesium, and phosphorus, respectively, was found from the landforms. Significantly strong relationships between NE and sediment yield in the landforms were observed. Annual nutrient replacement costs varied among the landforms though the highest was in the reservoir (€9204 in May 2010). This study thus suggests that while introducing antierosion measures, priority should be given to erosion sources to the reservoir such as mountainous and central ridge landforms.

Reversing Agro-Based Land Degradation through Conservation Agriculture: Emerging Experiences from Zambia’s Smallholder Farming Sector

<p>This study reports on the land degradation minimizing effects of Conservation Agriculture (CA) as promoted among smallholder Zambian farmers. It found no evidence of CA associated improvements in soil fertility after five years of CA practice, most probably because crop residues were removed from the fields. The study reports high phosphorus (15.53 mg kg^-1) and potassium (0.75 cmol kg^-1) levels, low nitrogen (0.12 %) and organic carbon (1.19 %) levels, and no plough/hoe pans in soils from both CA and conventionally (CV) managed fields. This is in part contrary to the dominant land degradation narratives which have been the basis for promoting CA in the study areas. <em>Faidherbia albida</em>, a leguminous tree promoted as part of the CA package in Zambia, is associated with significantly higher levels of nitrogen, organic carbon and potassium under its canopy. Its planting by CA farmers is linked to the incentives provided by CA promoters. Average maize yields of 3.8 t ha^-1 and 2.8 t ha^-1were reported under CA and CV systems respectively. Government subsidies for mineral fertilizer and hybrid seed promote maize mono-cropping and remain unsupportive of CA. It is concluded that the dominant land degradation narrative, which posits population induced land degradation, may not hold in this case. Instead, the removal of crop residues and low levels of mineral fertilizer and manure amendments may better explain the soil fertility status of the study areas. More nutrient replacement strategies are required if the benefits of CA on soil fertility are to be actualized in the immediate future.</p>