Abstract
Micronutrients and particularly zinc (Zn) deficiency affects crops productivity and human health, therefore improving Zn concentration within plant tissues might be regarded as an aim of sustainable agriculture. In this respect, a field experiment was carried out to examine the potential influence of preceding crop residues including bean and wheat incorporation into the soil as a way to improve zinc accumulation within subsequent wheat (Triticum aestivum L.) grain. The experiment was initiated at autumn 2014 and in the first year, a piece of farm land in Dehaghan-Isfahan-Iran was divided into two equal parts devoted to wheat and bean cultivation. At the end of the harvest season, aboveground plant residues were incorporated to 0-30 cm layer of soil. In the next year, the entire farm devoted to wheat production. The applied treatments included: control, zinc sulfate (60 kg/ha), wheat residues, bean (Phaseolus vulgaris L.) residues, wheat residues + zinc sulfate and bean residue + zinc sulfate. The results of analysis of variance showed the highly significant differences between treatments in terms of grain zinc, protein, phytic acid to zinc molar ratio (PA/Zn), quantitative yield and soil electrical conductivity (EC). Soil pH and organic carbon (OC) were not affected by treatments while soil EC significantly increased by using plant residues. The highest grain yield (3.8 t/ha), grain protein (10.3 mg/kg) and zinc concentrations (36 mg/kg) were obtained by using bean residues plus ZnSO4 while the lowest quantities were related to control treatment. The treatments had no significant impact on grain acid phytic concentration but phytic acid / zinc molar ratio was affected by treatments and the lowest ratio (which is a positive attribute) was measured from plots containing bean residues plus ZnSO4 while the highest occurred in control plots.