Theophilus K. Udeigwe

Implications of leading crop production practices on environmental quality and human health.

Globally, much weight is currently being placed on agriculture to provide food for the growing population as well as feedstock for the bioenergy industry. Unfortunately, the intensification of agricultural operations to satisfy these growing needs has been associated with a number of environmental and human health risks. A review of publications on the subject was conducted and emphasis was placed on articles focusing on agriculture, environment, and public health as well as their interactions. Supporting information was also gathered from publications of various agricultural and environmental agencies. Agricultural practices with potential negative implications on the environment and human health were identified broadly as: (a) utilization of biosolids and animal manures, (b) use of agricultural chemicals, (c) management of post-harvest residue, (d) irrigation, and (e) tillage operations. Soil, water, and air contamination by nutrients, heavy metals, pathogens, and pesticides, as well as air contamination by particulate matters, noxious gases, and pathogens were among the leading environmental impacts. Some of the human-health impacts identified included neurological and reproductive defects, cardiovascular risks, cancers and other diseases (of kidney, liver, lung, and skin), skin allergies, gastroenteritis, and methemoglobinemia. Continual awareness on the impacts of the reviewed agricultural practices on environmental quality and human health and the implementation of experimentally-backed best management practices in agricultural systems remain indispensable.

Geostatistical analysis of trace elements PXRF dataset of near-surface semi-arid soils from Central Botswana

Geospatial dataset of trace elements including manganese (Mn), iron (Fe), titanium (Ti), rubidium (Rb), strontium (Sr), thorium (Th), Vanadium (V) and Zirconium (Zr) of near-surface soils in a Cu–Ni prospecting field at Airstrip North, Central Botswana were statistically analysed. Grid sampling method was used in the field data collection. The relatively new portable X-ray fluorescence spectrometer (Delta Premium, 510890, USA) technology in a “soil” mode was used to measure the concentrations of trace elements in the soils. The data presented was obtained from the average reading of two soil samples collected from same point but passed through sieves. Sequel to DOI: 10.1016/j.dib.2016.08.026 (P.N. Eze, V.S. Mokosomani, T.K. Udeigwe, O.F. Oyedele, 2016) [1].

Kinetic and parametric studies for the extractive synthesis of oil from Terminalia catappa L. kernel

Non-linear kinetics and effects of process parameter variation for the extraction of Terminalia catappa L. kernel oil (TCKO) were investigated via solvent extraction. The non-linear kinetic models studied were: parabolic diffusion, power law, hyperbolic, Elovich, and pseudo-second order. Process variables considered were: kernel average particle size, time and temperature. In ascending order, the best fitted models are hyperbolic (average RMS; average SEE 0.04971; 0.6574) and pseudo-second order (average RMS; average SEE 0.04032; 0.5721). However, parabolic, power law and Elovich’s models failed to give adequate fitting to the experimental data. Physicochemical properties of the TCKO showed its potential for transformer oil production.

Quantitative geospatial dataset on the near-surface heavy metal concentrations in semi-arid soils from Maibele Airstrip North, Central Botswana.

This article contains a statistically analyzed dataset of the heavy metals including Cr, Co, Ni, Cu, Zn and Pb contents of near-surface (~30 cm depth) soils in a Cu–Ni prospecting field at Airstrip North, Central Botswana. The soils developed on paragneisses and amphibolites parent materials in a semi-arid environment with hardveld vegetation, “The geology of the Topisi area” (Key et al., 1994) [1]. Grid sampling was adopted in the field data collection. Heavy metals were determined using the relatively new portable x-ray fluorescence spectrometer (Delta Premium, 510,890, USA) technology in a “soil” mode. The data presented was obtained from the average reading of two soil samples collected from same point but passed through sieves.

Chemistry of Arsenic in Semi-Arid Alkaline Soils of the Southern High Plains, USA: Sorption Characteristics and Interactions with Soil Constituents

Limited information is available on the chemistry of arsenic (As) in the semi-arid alkaline soils of the Southern High Plains (SHP), USA. This study examined As sorption characteristics and its interactions with soil constituents in important agricultural soils (Amarillo, Arvana, Patricia, and Pullman) of the SHP using sorption isotherm models and sequential fractionation techniques. Results from fractionation of As into five distinct pools showed that about 52.4 % of the added As was found in the exchangeable and non-adsorbed pool in the Amarillo soil, suggesting this soil could have the highest tendency to release sorbed As to the environment, whereas the Pullman soil exhibited the greatest capacity to fix As as over 45 % of the added As was found in the residual fraction. The distribution of As among the soil constituents was a reflection of the characteristics of these soils. Arsenic sorption behaviors were well described by both the Freundlich and Langmuir models. Arsenic sorption maxima (qmax) was highest in the Amarillo soil (~2124 mg kg−1), followed by the Pullman, Arvana, and Patricia soils with qmax values of 1692, 1370, and 1317 mg kg−1, respectively. The Freundlich distribution coefficient (Kd) was highest in the Pullman soil (21.6 L kg−1) and lowest in the Amarillo (1.38 L kg−1). Sorption parameters such as Kd, N (sorption intensity constant) and qmax, varied among the soils, and the variability associated with Kd and N in these semi-arid soils was explained by soil properties such as pH, organic matter, calcium carbonate, total free iron (Fe), sand, clay, total aluminum, total Fe, and total manganese contents. Findings from this study are important in understanding the environmental fate of As in semi-arid/arid climates and could be extended to other regions with similar soil characteristics.

Copper micronutrient fixation kinetics and interactions with soil constituents in semi-arid alkaline soils

ABSTRACT This study examined the fixation pattern and kinetics of plant-available [diethylene triamine pentaacetic acid (DTPA)-extractable] copper (Cu), as well as basic soil properties that influence Cu availability in selected semi-arid soils. Soil samples from six different series were used and data obtained from Cu extraction experiments fitted to various kinetic models. Soils were also characterized for a suite of chemical and physical properties. The majority (80%) of the plant-available Cu fixed over the experimental period of 90 d occurred within the first 14 d. The amount of plant-available Cu fixed within the first 14 d tended to be influenced by the combination of organic matter (OM) and pH. The total amount of Cu fixed at the end of the experimental period of 90 d was influenced by pH and a combination of pH and calcium carbonate. The fixation of plant-available Cu over the experimental period was better described by the power function model [R2 = 0.90, Standard Error (SE) = 0.099] but poorly by the other models (R2: 0.58 to 0.59), while reactions within the first 35 d were better described by the second-order model (R2 = 0.98, SE = 0.008), suggesting a different fixation pattern. Findings from this study provide a basis for a more mechanistic approach to evaluating and comparing the fixation of Cu micronutrient compounds in these semi-arid soils for more scientific management decision making.

Diversifying Soybean Production Risk Using Maturity Group and Planting Date Choices

Due to the long growing season for soybean production, producers in the Mid-southern US can plant from late March to June. They also have a range of maturity group (MG) choices, affecting the length of the growing season, that are physiologically and economically viable. A producer’s decision of what to plant and when constitutes two potential decision variables that can be freely manipulated to not only maximize profit, but also reduce economic risk. Early maturing MG III and IV soybean cultivars planted early or mid-season typically are highest yielding and thereby the preferred choice of producers. However, planting part of a producer’s acreage at later dates and using later maturing MG VI soybeans may offer producers similar returns (as observed with early planting using early maturing cultivars) at a meaningfully reduced level of risk.

Plant-available zinc fixation kinetics in semi-arid alkaline soils of the Southern High Plains

ABSTRACT This study examined zinc (Zn) fixation pattern and kinetics in three semiarid alkaline soils of the Southern High Plains, USA. Soil chemical data obtained from Zn-extraction experiments conducted at different depths were fitted to various kinetic models to examine Zn fixation patterns. Within the experimental period of 90 days, approximately 57% of the total plant-available Zn fixed occurred in the first 14 days when averaged across all soils and depths. Zinc fixation over the experimental period (90 days) was better described by the power function (pfxn) model (R2 = 0.87–0.92, standard error [SE] = 0.130–0.154), but poorly described by the zero-, first- and second-order models (R2 = 0.55–0.76, SE = 0.038–0.267). Average reaction rate constant (from the pfxn model) was higher in the subsurface soils (0.323), suggesting a more rapid Zn fixation, compared to the surface soils (0.293). Zinc fixation within the first 35 days was also more rapid and better described by both the second-order (R2 = 0.91, SE = 0.018) and pfxn (R2 = 0.92, SE = 0.119) models. Findings are applicable to field settings and kinetic parameters obtained will help to advance Zn studies and management in these semiarid soils.