Contribution of Organic Amendments to Growth of Faba Bean and Maize Planted in Soil Exposed to Heavy Metals Pollution

ORGANIC materials, namely compost, biogas manure and …….. humic acid, were employed, individually, to improve growth of plants cultivated in a chemically polluted alluvial clay soil. A mixture of heavy metals, i.e. Zn+ Cu+ Pb intentionally introduced to the soil. Two rates of each of the organic and mineral substrates were examined, i.e. 0.5& 1.0%C for the organics and the permissible safe level of each mineral & duplicate that level, all besides the controls of such treatments. Faba bean (Vicia faba), as a winter legume, and maize (Zea mays), as a summer cereal, were used as test crops. Greenhouse pot experiments were carried out to achieve the purpose of the study. Traits of plant growth had been measured at two periods after planting, i.e. 45& 90 days for faba bean and 30& 60 days for maize.
The applied organic amendments proved to control the hazardous action of the heavy metals added to the soil. Elevating the dose of such treatments more efficiently handicapped the mobility of the heavy metals in soil medium to the favour of availability of nutrients and their plant absorption. This had been positively reflected on plant growth traits, namely plant height, dry mass and main macro-nutrient contents (N,P& K). Order among the organic substances used, as to diminish the passive action of used the heavy metals, was: humic acid> biogas manure> compost, at the first growth period, but compost and humic acid exchanged position later on. Faba bean relatively showed a lower susceptibility to the undesirable effect of the heavy metals than maize.