Isam I. Bashour

Morphology and composition of some soils under cultivation in Saudi Arabia

Abstract Twelve profiles representing the principal soils of five major agricultural areas (Al-Kharj, Gassim, Hofuf, Taif and Wadi Dawasir) in Saudi Arabia were described and sampled by horizons. Laboratory analyses were then made of the samples to characterize the profiles more completely. Analyses were also made for certain nutrient elements to get some measure of their levels in the soils. The profiles are tentatively classified in the Entisol and Aridisol orders of the American taxonomy. Five Entisol profiles were considered to be Fluvents and two Psamments. Four Aridisol profiles were considered to be Argids and one an Orthid. All of the profiles are saline and calcareous and most are also sandy. Furthermore, amounts of nutrient elements such as phosphorus, iron and zinc in surface layers are below minimum levels established for similar soils in earlier investigations in other countries. Consequently, the soils are believed to lack sufficient quantities of several elements for optimum plant growth. Successful use of the soils will thus require reductions in salinity, increased levels of nutrient elements, and skillful irrigation to provide adequate moisture.

Antibiotic uptake by plants from manure-amended soils.

Antibiotics are extensively given to livestock to promote growth and reduce diseases. Therefore, animal manure often contains antibiotics. Once manure is applied to agricultural land to improve soil productivity, crops would be exposed to antibiotics which may persist in soils from a few to several hundred days. The objective of this study was to evaluate the uptake of gentamicin and streptomycin by carrot (Daucus carota), lettuce (Lactuca sativa) and radish (Rhaphanus sativus) from manure-amended soil. The treatments were 0, 0.5 and 1 mg of antibiotic kg−1 of soil. Two pot experiments were carried out in the greenhouse. The first was conducted on the three crops and the second exclusively on radish. In radish, the increase in the concentrations of gentamicin was significant between the 0 and both of 0.5 and 1.0 mg kg−1 treatments, but not significant between the 0.5 and 1.0 mg kg−1. The average values were 35.5, 60.0 and 57.4 μg kg−1 for the 0, 0.5 and 1 mg kg−1 rates, respectively. However, the increase in streptomycin concentration in radish was not significant between the three treatments, and the average values were, 12.1, 15.2 and 17.4 μg kg−1 for the 0, 0.5 and 1 mg kg−1 rates, respectively. In carrot roots and lettuce leaves no significant increase in the concentrations of gentamicin or streptomycin was observed between the treatments. The three crops absorbed relatively higher amounts of gentamicin (small molecule) than streptomycin (large molecule). Generally the levels of antibiotics in plant tissue increased with increasing the antibiotic concentration in the manure (1 mg kg−1 > 0.5 mg kg−1).

DDT residues in Lebanese soils.

Abstract The present study was conducted to evaluate the levels of residual DDT in Lebanese soils. A total of 113 surface soil samples were collected for analysis from three major agricultural regions in the country: Mount Lebanon, Beqa’a valley and the coastal plain. The values of residual DDT in soils ranged between 0 and 1190 ng g−1. The majority of the analyzed soil samples were free or contained very low concentrations of DDE. Only two surface soil samples, which were collected from urban areas with high human activities, contained relatively high concentrations of residual DDT. The levels of residual DDT in all of the analyzed soil samples were within the permissible limits for agricultural soils.

Biodegradation of α and β Endosulfan in Soil as Influenced by Application of Different Organic Materials

Abstract A laboratory pot experiment was conducted to study the effect of amending soil with four different sources of organic matter on the degradation rate of α and β endosulfan isomers. Poultry by-product meal, poultry manure, dairy manure, and municipal solid waste compost were cured, dried, ground (<1 mm) and thoroughly mixed with a calcareous soil at a rate of 2% and placed in plastic pots. Endosulfan was added at the rate of 20 mg kg−1. The moisture level was kept near field capacity and the pots were kept at room temperature. Soil sub-samples, 100 g each, were collected from every pot at days 1, 8, 15, 22, 29, 43, and 57 for the measurement of endosulfan isomers. Endosulfan residues were extracted from the soil samples with acetone. The supernatant was filtered through anhydrous sodium sulphate, 5 mL aliquot was diluted to 25 mL with hexane, mixed well, and then two sub-samples from the filtrates were analyzed for α and β endosulfan isomers by gas chromatography. The results indicated that the half-life (T ½) of α-endosulfan in the poultry by-product meal treatment was 15 days compared to about 22 days in the other treatments. The T ½ of β-endosulfan was 22 days in the poultry by-product meal treatment and followed a bi-phasic pattern, 57 days in the municipal solid waste compost treatment and the extrapolated T ½ was about 115 days for the other three treatments.

Phosphorus fractionation in some soils of Saudi Arabia

Abstract Total amounts of phosphorus and quantities in the organic form and in various fractions of the inorganic form were determined in samples of surface layers of nine soils from five major agricultural areas of Saudi Arabia (Al-Hasa, Qassim, Wadi Dawasir, Al-Kharj and Taif). Total phosphorus ranged from 182 to 1088 ppm and organic phosphorus from 0 to 90 ppm. Among the fractions of inorganic phosphorus Ca-P was much the largest portion, ranging from 182 to 902 ppm. Al-P and occluded P were so low as to be negligible, whereas Fe-P and residual P were present in slightly larger amounts. Amounts of phosphorus extracted by NaHCO3 were below critical levels, according to observations elsewhere. Amounts of total P in four soil samples were lower than values reported for the soils of the western United States and Lebanon. Generally low amounts of organic phosphorus appear to be closely related to the organic matter contents of the samples.

Comparison of Gas Chromatography and Immunoassay Methods for Analysis of Total DDT in Calcareous Soils

Three different calcareous soil samples from Lebanon were analyzed for total DDT pesticide residue using GC and ELISA methods. Two experiments were conducted on three different calcareous soil samples. In each experiment, triplicates of 5 gm soil samples were each fortified with standard solutions of DDE to reach concentrations of 0, 5, 25, 50, 100 and 200 ng g− 1 and allowed to equilibrate at room temperature for 6 hours. Each sample was then extracted with 25 mL of 90% methanol by shaking in glass bottles on a mechanical shaker for 16 hours. The bottles were allowed to stand for 30 minutes and aliquots were taken from the clear supernatant for analyses without further cleanup. The total DDT in the extract was measured in triplicate by GC and ELISA. The results indicated that the two methods were highly correlated (R = 0.955–0.994). Differences in soil properties did not affect the accuracy of the detection limits of ELISA. Immunoassay technique can be used for rapid and accurate measurement of total DDT residues in mineral calcareous soils in Lebanon.

Soils and Food Security in the Arab World

The area of the Arab region is about 14 million Km2 (1.4 * 109 ha) of which about 90% lies in the arid and semi-arid harsh environments and fragile ecosystems. During the past three decades, limited efforts were put to combat soil degradation, and desertification and soil salinization are still the major environmental problems in the Arab region. The annual rapid increase in the population, in addition to the change in life style and the increase in food consumption, led to the widening of the void between production and consumption of food in the region.

Experimental evaluation of low-cost resistive soil moisture sensors

Soil moisture sensors are used mainly to help farmers to plan irrigation scheduling and save fresh water usage. The measurement of soil moisture based on electrical resistivity is widely used by farmers due to its simplicity and low cost. This research aims to evaluate the performance of low-cost resistive soil moisture sensors under greenhouse conditions. For this purpose, sensors have been assessed by several calibrations and evaluation experiments. Soil moisture percentages were logged daily to obtain curves relating moisture percentages to voltages provided by the sensors. The obtained results revealed that resistivity based sensors were affected by several sources of error, which lead to severe problems regarding accuracy and usability.

Uptake of Antibiotics by Plants

Antibiotics are bioactive substances that are given to human and animals for disease treatments. Antibiotics that are added to the feed of poultry, fattening livestock, and other meat-producing animals to promote growth and reduce illness are released in manure as the parent compound and/or their metabolites. When manure containing antibiotic residues is used as a plant fertilizer, it may become a potential risk for human, environment and consequently, they become available for plant uptake. Several researchers investigated this topic and argued about the common consumption of vegetables containing low levels of antibiotics may lead to the development of bacterial antibiotic resistance and plants are capable of spreading antibiotics from the soil into the food chain. Agriculture is only one source of antibiotics contamination among several other routes that poses risks to the environment and human health. The phytotoxicity of different classes of antibiotics varies in different soil types and plant species. This chapter provides an overview of antibiotics in soil-plant-system including the accumulation of antibiotics in different plants. As antibiotics are used in escalating quantities, there is a growing concern over the presence, toxicity, and fate of antibiotics in soil which may pose adverse effects on soil biology, crop yield, and quality of production.