Possible availability of Mg, Fe, Mn and Zn from organicaly produced maize

Trial was conducted during 2013 with aim to study application of different fertilizer combinations on availability of mineral nutrients Mg, Fe, Mn and Zn from organically produced maize grain. Fertilizer treatments included control (without fertilization), DIX 10 N and Italpolina 4:4:4, which were incorporated into soil, as well as foliarly applied MgSO4. After harvest, grain yield, 1.000 grain weight and content of nutrients Mg, Fe, Mn and Zn, as well as inorganic phosphorus (Pi), phytate– as factor which affect availability of mineral nutrients and β-carotene– as factor which promotes availability of mineral nutrients, were determined in grains. The highest grain yield and 1.000 grain weight were achieved in DIX treatment. MgSO4 showed positive impact on phytate decrease and β-carotene increase, but in combination with Italpolina and DIX, respectively. Meanwhile, the highest content of observed mineral elements was observed in control. The highest variation in relations of phytate with examined parameters was on phytate/β-carotene content, ranging from 411.3 (DIX+MgSO4) to 1825.9 (Italpolina). The desirable lowering in ratio between phytate and examined elements was achieved in DIX+MgSO4 combination, for phytate/Pi, phytate/β-+carotene and phytate/Mn ratio, while Italpolina decreased phytate/Zn ratio. However, phytate/Mg and phytate/Fe ratios were the lowest in control, indicating that applied fertilizers showed negative impact on potential Mg and Fe availability. Regression analysis underlined that phytate/Fe and phytate/Zn negatively correlated with 1.000 grain weight, indicating that bigger grains could be also valuable with increased Fe and Zn availability. That could be referred to DIX as treatment with the highest β-carotene content and 1.000 grain weight.