Soil fertility management for groundnut in the lowveld of Mpumalanga and north coastal plain of KwaZulu-Natal provinces of South Africa

Smallholder groundnut production contributes substantially to food security in Mpumalanga Lowveld (MLV) and in Manguzi, the northern coastal plain (NCP) of KwaZulu Natal (KZN), both of which are dominated by infertile structureless sandy soils. A study was conducted to obtain information on the chemical properties of the soils to guide fertilizer management for optimizing groundnut production on these soils. Soil samples were collected from representative sites in MLV and NCP, and analysed for pH, calcium (Ca), magnesium (Mg), potassium (K), phosphorous (P), zinc (Zn) and manganese (Mn) in the peg-zone (0-10 cm depth), root zone (10-40 cm depth) and subsoil (40-60 cm depth). The soils were largely acidic, with pH mostly falling below 5.5. The basic cation concentrations were generally low, and so were Zn and Mn concentrations. Nonetheless, with the exception of P and Mn, the soil concentrations of the other nutrients analysed were within ranges considered adequate for vegetative and reproductive growth of groundnut, though Zn was marginally so. General fertility management recommendations to inform agricultural extension are provided for groundnut production on the sandy soils based on the chemical analyses of the soils.

Study of Rhizobia Impact on Nutritional Element Concentration in Legumes

The concentration of nitrogen in the Earth’s atmosphere is about 78%, but most plants are not able to acquire it directly from the atmosphere. One of the most common ways for binding atmospheric nitrogen is the development of an efficient symbiotic system between legumes and rhizobia. The aim of this study was to compare how different legumes and rhizobia symbiosis systems affect the concentrations of nutrients and other elements in soya and faba beans. Seeds of plants were inoculated with a preparation of rhizobia just before sowing. Plant samples were collected at the flowering stage (vegetative parts) and during harvest (seeds). Samples were air-dried and analysed with inductively coupled plasma mass spectrometry (ICP-MS). Total nitrogen and carbon concentrations were determined with an elemental analyser (EA). The obtained results showed that inoculation of legume plants with rhizobia not only affected nitrogen uptake by plants but also uptake of other elements. Inoculation had an effect on mineral element uptake for both faba bean and soybean leaves, where a significant increase in Mg, P, K, and Ca was observed. Treatment of legume plants with rhizobia caused a decrease of P and K concentrations in seeds, and there were changes in Fe and Mn concentrations.

Cord Blood Manganese Concentrations in Relation to Birth Outcomes and Childhood Physical Growth: A Prospective Birth Cohort Study

Gestational exposure to manganese (Mn), an essential trace element, is associated with fetal and childhood physical growth. However, it is unclear which period of growth is more significantly affected by prenatal Mn exposure. The current study was conducted to assess the associations of umbilical cord-blood Mn levels with birth outcomes and childhood continuous physical development. The umbilical cord-blood Mn concentrations of 1179 mother–infant pairs in the Sheyang mini birth cohort were measured by graphite furnace atomic absorption spectrometry (GFAAS). The association of cord-blood Mn concentrations with birth outcomes, and the BMI z-score at 1, 2, 3, 6, 7 and 8 years old, were estimated separately using generalized linear models. The relationship between prenatal Mn exposure and BMI z-score trajectory was assessed with generalized estimating equation models. The median of cord-blood Mn concentration was 29.25 μg/L. Significantly positive associations were observed between Mn exposure and ponderal index (β, regression coefficient = 0.065, 95% CI, confidence interval: 0.021, 0.109; p = 0.004). Mn exposure was negatively associated with the BMI z-score of children aged 1, 2, and 3 years (β = −0.383 to −0.249, p < 0.05), while no significant relationships were found between Mn exposure and the BMI z-score of children at the age of 6, 7, and 8 years. Prenatal Mn exposure was related to the childhood BMI z-score trajectory (β = −0.218, 95% CI: −0.416, −0.021; p = 0.030). These results indicated that prenatal Mn exposure was positively related to the ponderal index (PI), and negatively related to physical growth in childhood, which seemed most significant at an early stage.

Elevated Fe and Mn Concentrations in Groundwater in the Songnen Plain, Northeast China, and the Factors and Mechanisms Involved

Groundwater is an essential source of drinking and irrigation water. However, elevated Fe and Mn concentrations in groundwater have been found in recent decades, which can adversely affect human health and decrease crop quality and yields. The roles of hydrogeochemical changes and groundwater pollution (exogenous reductive material inputs) in this have not been studied adequately. We determined the distribution of Fe and Mn concentrations in groundwater in the Songnen Plain, northeast China, which is known for elevated Fe and Mn concentrations, and investigated the factors and mechanisms involved in causing the elevated concentrations. Chemical and statistical analyses indicated that the Fe and Mn concentrations in groundwater significantly correlated with climate parameters (precipitation and temperature), surface features (altitude, distance from a river, soil type, soil texture, and land use type) and hydrogeochemical characteristics (chemical oxygen demand and NH4+, NO3−, and P concentrations). In particular, the Fe and Mn concentrations in groundwater are higher in areas containing paddy fields and water bodies than other land use type areas. Areas with groundwater containing ultra-high Fe and Mn concentrations have almost all of the favorable factors. The main reasons for the elevated Fe and Mn concentrations in groundwater in the study area are the Fe/Mn mineral-rich strata and soil with abundant organic matter acting as sources of Fe and Mn to the groundwater and the reductive environment in the lower terrain and areas containing water bodies favoring Fe and Mn dissolution in the groundwater. Inputs of pollutants from agricultural activities have caused the Fe and Mn concentrations in groundwater to increase. Future studies should be performed to study interactions between pollutants from agricultural activities and Fe and Mn in groundwater and develop environmental management strategies for preventing future increases in Fe and Mn concentrations and promoting sustainable development of agriculture.

The Fe (II) and Mn (II) adsorption in acid mine drainage using various granular sizes of activated carbon and temperatures

Acid mine drainage (AMD) from coal mining activities contains Fe and Mn concentrations that often exceed environmental quality requirements. This study aims to determine the effect of the coal material size and temperature on the adsorption process of Fe and Mn metals contained in AMD using activated carbon made with a composition of 60% coal and 40% ZnCl2. For characterizing activated carbon, surface morphological was analyzed using SEM method, and surface area was analyzed using BET method. Meanwhile, for measuring Fe and Mn concentrations, the researchers used atomic absorption spectrophotometry. The adsorption process was carried out with various granular sizes of activated carbon (20, 28, 35, 48 and 60 mesh) and temperature (25, 35, 40, 45 and 50°C). The results showed that the maximum adsorption of Fe was 100% occurred in the treatment with an activated carbon size of 60 mesh and a temperature of 45°C, while the maximum adsorption of Mn was 11.91% in the treatment with an activated carbon size of 60 mesh and a temperature of 50°C. Furthermore, the activated carbon of coal is highly effective as an adsorbent for Fe in AMD waste but less effective for Mn.

Management of Iron and Manganese Toxicities of Lentil Crops Grown in Central Chile

Iron (Fe) and manganese (Mn) toxicity is a widespread problem in lentil production in the coastal dryland of Chile. Increasing the soil pH by liming with CaCO3 or incrementing grain yields through nitrogen fertilization can help the plants to reduce metal concentration. Thus, the main objective of this work was to evaluate two different fertilization strategies (lime (CaCO3) and nitrogen (N) additions) to reduce Fe and Mn toxicities in lentils. Lentils grown under field conditions with the highest Fe and Mn concentrations showed toxicity symptoms, but without grain yield reductions. In a pot experiment using the same soil as in the field with toxicity symptoms, the dry matter (DM) produced at the end of the trial was higher in the plants that received N while the lowest DM production was recorded in those plants treated with lime. In particular, higher root DM sustained the growth of the N-fertilized shoots, which also positively affected the grain yields being 33% higher than the control treatment (no fertilization addition). In the plants fertilized with N, the Fe and Mn levels in the shoots were lower than the control plants and those grown in soils treated with lime, but showed higher concentrations of Fe and Mn in roots. In parallel, roots exhibited high concentrations of Fe and Mn that were 13- and 9-fold higher than in the shoots. Additionally, a significant decrease of 29% in Mn concentration in the grains of plants treated with N was reported. Overall, our results suggest that an increase in DM of lentils by the addition of N can reduce the Mn concentration on leaves to a level that is likely under the threshold that causes toxicity in plant tissues. Finally, we conclude that the increase of Fe and Mn in the roots may be connected to the reduction of these metals on leaves.

First evaluation of iron and manganese concentrations in coastal aquaculture water in Giao Thuy district, Nam Dinh province

Aquaculture in the coastal zone has contributed significantly to economic development in Giao Thuy district, Nam Dinh province. Therefore, water quality for aquaculture plays a vital role in sustainable aquaculture production. In this paper, iron (Fe) and manganese (Mn) concentrations in aquaculture coastal water of Giao Thuy district were analyzed during the rainy season (September 2017, August 2018) and dry season at low tide. The results showed that Fe concentration varied from 0.09 mg/L (at VT5) to 2.42 mg/L (at VT4), averaging 1.12 ± 0.71 mg/L, which exceeded the critical value of the national technical regulation on marine water quality in Vietnam for coastal aquaculture water (QCVN 10:2015/BTNMT) from 1.5 times (at VT4) to 3.0 times (at VT1). Mn concentrations ranged from 0.02 mg/L (at VT9) to 0.10 mg/L (at VT1), averaging 0.05 ± 0.02 mg/L, which was lower than the critical value in the QCVN 10:2015/BTNMT. The results showed that no apparent seasonal variation was observed for both Fe and Mn concentrations. In the dry season, the Fe and Mn concentrations averaged 1.10 mg/L and 0.05 mg/L respectively, whereas they were 1.15 mg/L and 0.05 mg/L in the rainy season. The monitoring results showed that Fe was polluted in the study area and may affect aquaculture productivity. Therefore, helpful measures should be taken to minimize Fe pollution to protect water quality and develop sustainable aquaculture in Giao Thuy district, Nam Dinh province.

Association of Manganese Biomarker Concentrations with Blood Pressure and Kidney Parameters among Healthy Adolescents: NHANES 2013–2018

Deficiency or excess exposure to manganese (Mn), an essential mineral, may have potentially adverse health effects. The kidneys are a major organ of Mn site-specific toxicity because of their unique role in filtration, metabolism, and excretion of xenobiotics. We hypothesized that Mn concentrations were associated with poorer blood pressure (BP) and kidney parameters such as estimated glomerular filtration rate (eGFR), blood urea nitrogen (BUN), and albumin creatinine ratio (ACR). We conducted a cross-sectional analysis of 1931 healthy U.S. adolescents aged 12–19 years participating in National Health and Nutrition Examination Survey cycles 2013–2014, 2015–2016, and 2017–2018. Blood and urine Mn concentrations were measured using inductively coupled plasma mass spectrometry. Systolic and diastolic BP were calculated as the average of available readings. eGFR was calculated from serum creatinine using the Bedside Schwartz equation. We performed multiple linear regression, adjusting for age, sex, body mass index, race/ethnicity, and poverty income ratio. We observed null relationships between blood Mn concentrations with eGFR, ACR, BUN, and BP. In a subset of 691 participants, we observed that a 10-fold increase in urine Mn was associated with a 16.4 mL/min higher eGFR (95% Confidence Interval: 11.1, 21.7). These exploratory findings should be interpreted cautiously and warrant investigation in longitudinal studies.