Optimization of parameters affecting organic mulch test to control erosion

Wind erosion is considered as one of the most influential factors in the destruction of land in arid and deserted areas. There is a weak ecosystem in arid lands which wind erosion can move soil particles. Mulch is a compound that is used nowadays to control wind erosion. This study aims to create organic mulch in order to prevent wind erosion and environmental pollution. In order to create this type of mulch, different available materials such as blackstrap, manure, biosolids, and straw have been used. Response Surface Methodology (RSM) was applied to create this kind of mulch as well. Also, Central Compound Design (CCD) in RSM modeling was applied to optimize the mulch compound so as to decrease erosion and increase the thickness of crust and its penetration. In addition, each variable was coded and the concentration of straw effect (2-10 g m^-2), biosolids (8-24 g m^-2), manure (8-24 g m^-2) and blackstrap (5-15 g m^-2) on wind erosion and penetration were studied. The optimum values of crust thickness (1.5 mm) for straw, manure, blackstrap, and biosolids were 12.48, 19.94, 7.16, and 16.70 g respectively. The optimum values for penetration resistance for straw, manure, blackstrap, and biosolids were 11.31, 15.71, 4.36, 19.24 g as well. As these materials were used more and more in the compound, penetration resistance soared due to adhesion and crust in the compound. However, more use of blackstrap brought about a reverse result. The results indicated that there was not a considerable difference between predicted data and experimental data, and the model was acceptable in simulation.

The effect of sewage sludge on heavy metal concentrations in wheat plant (Triticum aestivum L.)

The use of sewage sludge in agricultural soils can improve soil physical and chemical properties and soil fertility by increasing organic materials; however, the presence of heavy metals in sewage sludge is a significant problem for the quality of agricultural products and the environment. Most heavy metals, due to their inactive nature, are stable and can affect human health. This study investigates the effect of sewage sludge on the concentration of copper, zinc, cadmium, lead, iron, and manganese in two varieties of wheat, i.e., Sivand (Triticum aestivum cv. Sivand) and Roshan (Triticum aestivum cv. Roshan). Results were obtained from a factorial experiment in a completely randomized design with three replications and at three levels (0, 60, and 120 kg soil) and were carried out in a research greenhouse. This research concluded that in the treated seed and stem of Sivand variety, concentrations of Zn, Cd, Fe, and Mn were below the standard toxicity limit, and concentrations of Cu and Pb were above the standard limit. In the Roshan variety, the concentrations of Zn, Cd, Pb, Fe, and Mn were below the standard limit, and Cu concentration was above the standard. The results of this study lead to the recommendation that farmers avoid using sewage sludge in farming, as much as possible. Instead, it is far more appropriately employed as a fertilizer for green space, ornamental trees, and parks, where edible products for human consumption are not grown.