Low Quality of Crops Produced in Salt-affected Soils
as a Great Challenge for Human Health

Amir Hossein Khoshgoftarmanesh

Department of Soil Science, College of Agriculture, University of Technology, Isfahan, Iran
e-mail: amirhkhosh@cc.iut.ac.ir

Abstract

Soil salinity is an important ecological problem in the landscape of semi-arid and arid regions of the world. Saline soils represent over 30% of arable lands in Iran. The environmental implications of salinization in terms of food quality by crops have yet to be fully assessed. There is evidence of enhanced Cd uptake by wheat that is a major diet for Iranian people. Greater available Cd reduces concentration of micronutrients especially Zn in wheat grain.
The aim of this study was to find the effect of salinity on nutritional quality of food chain (soil-crop-human) in some parts of central Iran. Iron (Fe), zinc (Zn), and cadmium (Cd) levels in soil, grain of food crops (wheat, barley, and sunflower), and female subjects (hair and serum) were determined in two different but relatively close regions with saline and non-saline soils. Thirty wheat crops and associated surface soils (0-25 cm) were sampled in each region. Electrical conductivity (ECe) and DTPA-extractable Zn, Fe, and Cd were measured in each soil. Grain Fe, Zn, phytic acid, and Cd concentrations were determined along with the serum and hair Fe, Zn, and Cd levels of the female subjects.
Soil ECe in the regions with non-saline and saline soils was in the range of 0.6 to 3.1 and 4.2 to 12.4 dS m^-1, respectively. The mean Cd level in the soil was significantly (p<0.05) different between saline (0.03 ug g^-1) and non-saline (0.11 ug g^-1) soils. Soil Cd level in non-saline soils was within the range expected for unpolluted soils while relatively high DTPA-extractable Cd levels were found in most saline soils especially where high amount of P-fertilizers had been used.
Most studied soils in both regions were Zn-deficient with DTPA-Zn concentrations <2.0 mg kg^-1, although there was no significant difference in soil available Zn between saline and non-saline soils. For all three studied crops (wheat, barley, and sunflower), grain Cd, Fe, and Zn concentrations varied greatly between two regions. The mean grain Zn and Fe concentrations were significantly higher in non-saline soils than in saline soils. In contrast, food crops produced in saline soils had significantly greater Cd concentration in their grain than the crops grown in non-saline soils.
Mean hair and serum concentrations of Zn and Fe in 160 female students (13-22 year) were low compared to the normal range of them. There was no significant difference in nutritional status between people living in the saline and non-saline regions. This may be partly due to the same quality of flours distributed to the bakeries within the studied regions. The method used for preparation of the bread is also relatively similar among bakeries. Reduced Fe and Zn and enhanced Cd concentrations in the food chain are some of the consequences of salinity and poor fertilizer management in the region with saline soils. Therefore, these studies revealed the fact that low nutritional quality of cereal grain, and as a result, poor nutrition is one of the most important challenges of salt accumulation in the soil.