Micronutrients as Impurities of Inorganic Fertilizers Marketed in Saudi Arabia

Inorganic fertilizers with major nutrients are likely to be contaminated with some micronutrients. Fertilizers, utilized in Saudi Arabia, were analyzed for their total and water-soluble content of Fe, Zn, Mn and Cu. They represented three categories namely: phosphatic, solid multiple nutrient fertilizers (SMNF) and water-soluble multiple nutrient fertilizers (WSMF). Total iron content in examined fertilizers was higher in phosphatic fertilizers and lower in WSMF. Nevertheless, only a very small portion of the total iron content is likely to be available to plants. It was estimated, on the basis of total content, that almost 2 g of iron would be applied to soil for each added kg of phosphatic fertilizer. The highest total content of Zn was recorded for phosphatic fertilizers. The data suggested that less than half kg of Zn would be accumulated in soil if 500 kg of phosphatic fertilizers were applied in one year. This value however, fell dramatically, to one fourth of the value, when only the available forms of Zn were considered. Fertilizer content of manganese and copper were lower than both Fe and Zn. Micronutrient impurities present in inorganic fertilizers might not have an immediate influence on plant nutrition due to their lower solubility

Micronutrients as Impurities of Inorganic Fertilizers Marketed in Saudi Arabia

Inorganic fertilizers with major nutrients are likely to be contaminated with some micronutrients. Fertilizers, utilized in Saudi Arabia, were analyzed for their total and water-soluble content of Fe, Zn, Mn and Cu. They represented three categories namely: phosphatic, solid multiple nutrient fertilizers (SMNF) and water-soluble multiple nutrient fertilizers (WSMF). Total iron content in examined fertilizers was higher in phosphatic fertilizers and lower in WSMF. Nevertheless, only a very small portion of the total iron content is likely to be available to plants. It was estimated, on the basis of total content, that almost 2 g of iron would be applied to soil for each added kg of phosphatic fertilizer. The highest total content of Zn was recorded for phosphatic fertilizers. The data suggested that less than half kg of Zn would be accumulated in soil if 500 kg of phosphatic fertilizers were applied in one year. This value however, fell dramatically, to one fourth of the value, when only the available forms of Zn were considered. Fertilizer content of manganese and copper were lower than both Fe and Zn. Micronutrient impurities present in inorganic fertilizers might not have an immediate influence on plant nutrition due to their lower solubility. 

Heavy Metals Content of Commercial Inorganic Fertilizers Used in the Kingdom of Saudi Arabia

In recent years much concern has been given to toxic heavy metals, which enter the human food chain. Application of inorganic fertilizers is considered one of the potential routes of such entry, in this work 74 samples of commercial fertilizers marketed in the Kingdom of Saudi Arabia were analyzed for their heavy metal concentrations. Fertilizer samples included 20 samples of phosphatic fertilizers [monoammonium phosphate (MAP), diammonium phosphate (DAP) and triple superphosphate (TSP)], 11 samples of liquid fertilizers. 31 samples of water-soluble multiple nutrient fertilizers (WSMF) and 12 samples of solid multiple nutrient fertilizers (SMNF). Concentrations of heavy metals varied according to the type of fertilizer and the tested metal; Cr levels were the highest and Co was the lowest. Results revealed that Cd ranged from < l to 36.8 mg.kg-1, with a median of 33.2 mg.kg-1 for the phosphatic fertilizers, 9.5 mg.kg-1 for the liquid fertilizers, 19.7 for the SMNF, and 2.9 mg.kg-1 for the WSMF. The median values of Pb, Ni, Co and Cr in the phosphatic fertilizers were 14.3, 72.1, 1 1.8 and 249.3 mg.kg-1, respectively. However, the corresponding median values of these elements, in the liquid fertilizers, were 9.9, 15.6, 11.2 and 64.0 mg.kg-1 and 15.3, 43.0, 12.5 and 170.7 mg.kg-1 in the SMNF. The median contents of three heavy metals in the WSMF samples were 9.8 mg.kg-1 for Pb, 5.6 mg.kg-1 for Co. and 7.4 mg.kg-1 for Ni. The Cd. Co. Cr and Ni concentrations were lower than the tolerance limits for heavy metal addition (Cd 100 mg.kg-1, Cr, 100 mg.kg-1 and Ni, 50 mg.kg-1), and they were in a range similar to those found internationally. It is estimated that the application of an average dose of 80 kg P ha-1 annually in Saudi Arabia, contributes 13 g of Cd ha-1 to the soil

Soil phosphorus fractionation in calcareous soil as affected by organic amendments application

Understanding of P transformations following organic amendments addition to highly calcareous soils is necessary for developing better management practices that can help enhance P fertilizer use efficiency. Phosphorus solubility and availability for plant uptake under the con- ditions of arid calcareous soil is very low, making P nutrient supply a critical issue under these conditions. The aim of this study was to evaluate the impact of various types of organic amend- ments (chicken compost, cow compost and a mixture of humic-fulvic acid) applied alone at dif- ferent rates of KH 2 PO 4 fertilizer on P fractions in calcareous soil using the sequential chemical extraction method. Amended calcareous soil was incubated under laboratory conditions and soil samples were collected at 0, 4, 8 and 16 weeks of the incubation periods. Soil was sequentially extracted and analyzed for P different fractions. The results indicated that the addition of chicken and cow compost increased soluble and exchangeable-P and Ca-P fractions in calcareous soil and the increases depend on application rates. The results indicated that combination of chicken and cow compost with different KH 2 PO 4 fertilizer application rates increased the concentration of sol- uble and exchangeable-P in the soil compared to organic amendments or KH 2 PO 4 fertilizer applied alone. The P associated with Ca was the dominant P fractions in soil, ranging between 51 to 59% regardless of the different treatment and the period of incubations. The Al- and Fe-associated Pfractions varied between 2 and 9%, with the maximum value being observed at the eighth week of incubation. The residual-P fraction ranged between 5 and 22% at different incubation periods