Volume 8, Issue 32 (2011)                   FSCT 2011, 8(32): 11-21 | Back to browse issues page

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Abstract:   (8223 Views)
  Paying a heavy subsidy just on N and P-fertilizers has caused farmers to overuse these fertilizers in the country and hence, more than 90% of the fertilizer use constitutes N and P-fertilizers on the irrigated wheat farms. Due to continuous imbalanced fertilization, especially the overuse of P-fertilizers and the absence of Zn-fertilizers in the farmers’ conventional fertilization practice, there has been an increase in the concentration of phytic acid (C6H18O24P6) in the wheat grains. Increased level of phytic acid (PA), would lead to a high molar ratio of phytic acid to zinc (PA/Zn) in wheat grains up to around 60. Phytic acid combines with metal cations in the digestive system  and converts them to phytate complexes which do not get absorbed in the human body. Presence of higher PA has been mentioned as a reason for discarding the wheat bran. Removing bran from the wheat grains is the fastest and easiest way of discarding PA.  According to the World Health Organization (WHO), for absorption of nutrients by digestive system in human body, PA/Zn index must be less than 25. Due to calcareous nature of the studied soils and continuous imbalanced fertilization, especially the overuse of P-fertilizers, PA/Zn molar ratio is around 60.  Since the main part (70%) of mineral nutrients, vitamins and PA are accumulated in the wheat bran, the authorities; instead of scientifically solving the problem- i.e. reducing PA and increasing Zn concentration in wheat grains- have decided to take away bran from the wheat kernel in the process of flour preparation. By removing subsidies in the 5th Development Plan, since the price of bread will increase significantly, so it is necessary to increase the quality of the bread. To achieve high quality bread, concentrations of PA and Zn should decrease and increase, respectively. This is possible only through the enrichment of wheat in the farm by the use of balanced fertilization, eliminating subsidy on P-fertilizers and allocating subsidy to zinc, bio- and organic fertilizers in order to reduce PA/Zn index. Various studies in the past two decades have shown that if current imbalanced fertilization is continued, PA/Zn index will be well around 60, necessitating the removal of the bran. But, if balanced fertilization is adopted as a general practice by the country's farmers, this ratio will decrease and it will not be necessary to remove the bran in flour processing. It is suggested to remove the subsidy from N and P-fertilizers and allocate them to Zn, biological and organic fertilizers, as well as conducting soil and plant analysis to determine required fertilizer levels. Phosphate fertilizers must be given to the farmers only on the basis of soil tests.  Imposing heavy penalties on the bakers who illegally use baking soda instead of yeast and implementing optimal fertilizer management practices will result in crop enrichment in wheat farms, which, in addition to achieving sustainable production of healthy crops, will contribute to upgrading Iranian society’s health-rating. By practicing balanced fertilization, applying zinc sulfate and bio-organic fertilizers, the country's nutrition will improve and the quality and quantity of whole wheat bread will be upgraded significantly, and hence the problem of malnutrition will be solved in the Iranian society.
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Received: 2011/04/11 | Accepted: 2011/07/24 | Published: 2012/06/27

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